US3720979A - Biased hinges - Google Patents

Abstract

A snap-hinge in which two hinge members are hinged together about a first hinge line. A resilient connecting link is joined at one end integrally to one of the hinge members at a second hinge line and is hinged at the other end to the other hinge member at a third hinge line. The connecting link is capable either of compression or of expansion as between its two ends, and tends to maintain the hinge members in a given angular relationship, and to return the hinge members to that relationship if they depart from it.

Description

United States Patent [191 Krawagna )March 20, 1973 [54] BIASED HINGES [75] Inventor: Alois A. Krawagna, Willowdale, On-

tario, Canada [73] Assignee: Western Corporation Toronto, Ontario, Canada [22] Filed: June 17, 1968 [211 Appl. No.: 744,268

Related US. Application Data 7 Limited,

[63] Continuation-impart of Ser. No. 689,390, Dec. 11,

[52] US. Cl ..16/l50, 24/252 [51] Int. Cl. ..E05d 7/00 [58] Field of Search ..16/l50;'24/l37 R, 137A, 252 24/252 HC, 252 R; 229/2.5

[56] References Cited UNITED STATES PATENTS 3,289,877 12/1966 Wolf ..16/l50 3,292,223 12/1966 Esposito ..24/ 137 Primary ExaminerBemard A. Gelak Assistant Examiner-Doris L. Troutman Att0rney-Thomas T. Rieder [57] ABSTRACT A snap-hinge in which two hinge: members arehinged together about a first hinge line. A resilient connecting link is joined at one end integrally to one of the hinge members at a second hinge line and is hinged at the other end to the other hinge member at a third hinge line. The connecting link is capable either of compression or of expansion as between its two ends, and tends to maintain the hinge members in a given angular relationship, and to return the hinge members to that relationship if they depart from it.

5 Claims, 22 Drawing Figures PATENTEUMAR20 I975 SHEET 10F 4 P INVEN ALOIS A. KR'AWAGN PATENT AGENT PATENTEDMARZO I975 3.720.979

SHEET 2 [IF 4 INVENTOR. ALOI S A. KRAWAGNA PATENT AGENT V PATENTEBIMRZOIQYS 3.720379 sum 30F a I N VENTOR ALOIS A. KR WAGNA PATENT AGENT PATENTEUMARZO 1975 3. 720.879 SHEET u 0F 4 138 FIG. 21 134 I N VEN 7( )R A OIS AQNA Agent BIASED HINGES This application is a continuation-in-part of US. application, Ser. No. 689,390, Improvements in Biased Hinges, filed Dec. 1 1, 1967, Alois A. Krawagna.

This invention relates to biased hinges, or snap-hinges as they are sometimes called, in which the hinge tends to hold itself in a closed position and/or an open position.

Snap-hinges of the type to which this invention relates include two hinge members hinged to one another, and a biasing member extending between and hinged to both hinge members at points spaced from the hinge line between the hinge members. In accordance with the invention, two basic types of biasing member can be utilized: the first is a biasing member adapted to undergo compression as between its two ends; the second is a biasing member adapted to undergo expansion as between its two ends. With regard to both the compression and the expansion types of biasing members, this invention provides that at least one end of the biasing member be integral with its particular hinge member.

In accordance with one embodiment of this invention, the two hinge members are pivoted together, and the biasing member is adapted to undergo compression. The biasing member is pivoted to one of the hinge members but integral with the other. This permits the hinge member with which the biasing member is integral to be moulded as a single unit adapted for use with one of a variety of rigid members constituting the other hinge member.

In accordance with the second embodiment of this invention, the two hinge members are integral with one another through a web constituting the hinge line about which the hinge members articulate, and the biasing member is integral with one of the hinge members through a web constituting a second hinge line, and is integral with the other hinge member at a point constituting a third hinge line, the biasing member being adapted to undergo compression. With this arrangement, the compression force on the biasing member tends to urge the two hinge members away from one another when the hinge is articulated. This feature is particularly advantageous in that it places the web portion joining the two hinge members in tension, and avoids the danger of shearing which accompanies compression in the web.

In accordance with a third embodiment of this invention, there is provided a one-piece, integral snap-hinge wherein the biasing member undergoes expansion, the two hinge members being connected through an integral web constituting the hinge line about which the hinge members articulate. The biasing member has its opposite ends integral with the two hinge members through webs constituting further hinge lines. The further hinge lines are spaced from the first hinge line.

In accordance with a fourth embodiment of this invention, there is provided a snap-hinge in which one of the hinge members consists of two separate but interlocking parts. The other hinge member is a one-piece unit, and the construction of the whole is such that the biasing member links the one-piece hinge member with one part of the other hinge member, and the one-piece hinge member is adapted to engage the other part of the other hinge member to hold the two parts firmly in interlocking engagement with one another. The one piece hinge member can be removed from engagement with the other part, thereby permitting the two parts of the two-part hinge member to be separated completely from one another.

This invention also provides a method for making by the extrusion method a snap-hinge: in which the biasing member undergoes expansion.

Specifically, this invention provides a snap-hinge, comprising: a first hinge member, a second hinge member hinged to said first hinge member about a first hinge line, a resilient connecting link joined at one end 1 integrally to said first hinge member at a second hinge line and hinged at the other end to said second hinge member at a third hinge line, the resilient connecting link tending resiliently to maintain its two ends apart at a given spacing, said second hinge line being spaced at an invariable distance from said first hinge line, said third hinge line being spaced at an invariable distance from said first hinge line, the snap-hinge having a position in which stress in the connecting link is at a minimum, the snap-hinge being at rest in said position, a small departure from which increases the stress in the connecting link, which tends to restore the snap-hinge to said position.

The embodiments of this invention are shown in the accompanying drawings, in which like numerals denote like parts throughout the several views, and in which:

FIG. 1 is a perspective view of one embodiment of this invention;

FIG. 2 is a sectional view taken along the line 2-2 in FIG. 1;

FIG. 3 is a sectional view of the hinge shown in FIG. 2, with one hinge member hinged to an intermediate position with respect to the other hinge member;

FIG. 4 is a sectional view of the hinge shown in FIGS. 2 and 3, with the hinge members closed together;

FIG. 5 is a perspective view of the second embodiment of this invention;

FIG. 6 is a sectional view taken at the line 6-6 in FIG. 5;

FIG. 7 is a sectional view of the hinge shown in FIG. 5, with the hinge members closed against one another;

FIGS. 8 and 9 show two modifications of the second embodiment of this invention;

FIG. 10 is a perspective view of one form of the third embodiment of this invention;

FIG. 11 is a frontal view of the embodiment shown in FIG. 10;

FIG. 12 is an elevational view of an extruded form of the third embodiment of this invention;

FIG. 13 is a cross-sectional view of the extruded third embodiment shown in FIG. 12;

FIG. 14 is a view similar to FIG. 13, showing the two hinge members at an intermediate angular position;

FIG. 15 is a view similar to FIGS. 13 and 14, showing the two hinge members closed against one another;

FIG. 16 is a perspective view of a special form of the first embodiment of this invention;

FIG. 17 is a perspective view of one variant of the fourth embodiment of this invention, showing the two portions of the two-part hinge member in spaced relation;

FIG. 18 is a vertical, longitudinal sectional view of the embodiment shown in FIG. 17, with the two portions of the two-part hinge member engaged with one another;

FIG. 19 is a view similar to FIG. 18, showing the locking hinge member at its balance point, about to be urged to the over-toggled locking position;

FIG. is a view similar to FIGS. 18 and 19, showing the locking hinge member in the locked position;

FIG. 21 is an elevational view of another variant of the fourth embodiment of this invention, wherein the biasing member is bowed in order to increase its capacity for expansion; and

FIG. 22 is a perspective view of the variant shown in FIG. 21.

FIG. 1 shows ahinge 10, generally comprising afirst hinge member 11 and asecond hinge member 12. The first hinge member 1 1 has twoparallel arms 14 extending leftwardly from thehinge member 11, thearms 14 being rigid with respect to thehinge member 11. Thesecond hinge member 12 has two rightwardly protrudingappendages 16, which are rigid with respect to thehinge member 12. Thearms 14 each carry a pivot pin 17 (only one visible in FIG. 1) by which thearms 14 are pivoted to theappendages 16. Thus, thesecond hinge member 12 is hinged to thefirst hinge member 11 about afirst hinge line 18, which constitutes the common axis of the pins 17. Thefirst hinge member 11 has a resilient connectinglink 20 integral therewith between thearms 14, and extending leftwardly toward thesecond hinge member 12. It will be noted that thelocation 22 at which the resilient connectinglink 20 is integral with thehinge member 11 is spaced from thefirst hinge line 18.

The resilient connectinglink 20 has apin 24 passing therethrough at its left-hand end, and the ends of thepin 24 are pivoted to theappendages 16 at a location spaced from thefirst hinge line 18. The axis of thepin 24 constitutes asecond hinge line 26. It is essential to this invention that the first andsecond hinge lines 18 and 26 be spaced rigidly from one another.

Turning now to FIG. 2, it will be seen that the righthand end of the connectinglink 20 is rigidly integral with thefirst hinge member 11, sincethe connectinglink 20 does not decrease in thickness to form a flexible web where it joins thehinge member 11. By comparison, a glance at FIGS. 8 and 9 shows the connecting link to be hingedly integral with the hinge member, due to the flexible web portion connecting them.

Returning to FIG. 2, it is assumed here that the position of thehinge members 11 and 12 shown is the normal at-rest open position for the hinge, with the hinge members being 180 apart. In this position, the connectinglink 20 is subject to the least compression bowing stress of any position between FIG. 2 and FIG. 4. If thefirst hinge member 11 is formed with the integral connecting link originally parallel with thearm members 14, some bowing stress will be introduced into thelink 20 when its left-hand end is raised and pivoted to theappendages 16 along thesecond hinge line 26. Alternatively, thefirst hinge member 11 can be formed with the resilient connectinglink 20 already in the slightly curved configuration shown in FIG. 2. It will be noted that thearms 14 and thehinge member 11 are considerably thicker in the vertical direction than is the connectinglink 20. The purpose of the relative difference in thicknesses is to make the connecting link 20 a relatively resilient or bendable member, as compared to the morerigid hinge member 11 andarms 14, even though thehinge member 11, thearms 14 and the connectinglink 20 are all formed of the same material.

As thefirst hinge member 11 begins to pivot in the counter-clockwise direction with respect to thesecond hinge member 12, it will be obvious that, due to the spacing between the hinge lines 18 and 26, the ends of the resilient connectinglink 20 will be urged together to place the link in compression, and the result will be a compression bowing in the connectinglink 20.

FIG. 3 shows the bowing of the resilient connectinglink 20 at its maximum, and this is determined by the alignment of the hinge lines 18 and 26 and thepoint 28, which can be considered the approximate point of attachment between the resilient connectinglink 20 and thefirst hinge member 11. The geometry of the system is such that the two ends of the resilient connectinglink 20 are closest when thepoint 28 is lined up with the hinge lines 18 and 26. The amount by which the rectilinear distance between the ends of the connecting link is shortened in FIG. 3 is shown as D. As thefirst hinge member 11 moves leftwardly in the counterclockwise direction past the FIG. 3 position, the resilient connectinglink 20 begins to straighten out, but it is still not completely relieved of compression bowing stress when thehinge members 11 and 12 have closed upon one another. The reason for this is the fact that thehinge line 26 is slightly to the left of thehinge line 18. Explanations of this intentional residual compression spring loading and other angular travel relationships are contained in later paragraphs.

Returning to FIG. 2, it will be appreciated that, because thehinge line 26 is spaced upwardly from thehinge line 18, as soon as thehinge member 11 begins to pivot in the counter-clockwise direction above thehinge line 18 and compress the resilient connectinglink 20, the latter will exert a force on thefirst hinge member 11 tending to return it to the FIG. 2 position. The torque T tending to return thefirst hinge member 11 to its FIG. 2 position will be given by the relationship:

T= FL (sin :1)

where L is the distance between thehinge line 18 and thepoint 28, F is the compressive force exerted on the resilient connectinglink 20, and d) is the angle in the vertical plane subtended at thepoint 28 by the hinge lines 18 and 25. The angle d) is shown in FIG. 2.

It will be appreciated that, when thefirst hinge member 11 has reached the FIG. 3 position, where thepoint 28 is lined up with the hinge lines 18 and 26, the angle 4: drops to zero, and the restoring torque T likewise drops to zero. Thus, when the hinge is in the FIG. 3 position, it is in a condition of unstable equilibrium. As thefirst hinge member 11 moves past the FIG. 3 position in the counter-clockwise direction, the angle d increases from zero to a finite value, and causes a torque in the counter-clockwise direction which is also given by the expression above. Because the resilient connectinglink 20 is still under some compression in the FIG. 4 position, thehinge members 11 and 12 are urged together in the FIG. 4 position.

It will be appreciated that thesecond hinge member 12 need not be in the exact shape shown, since its sole function is to provide connecting portions for the pivot pins 17 and 24.

Turning now to FIG. 5, which shows the second embodiment of this invention, it will be seen that a hinge shown generally at 30 comprises afirst hinge member 31 and asecond hinge member 32. Thefirst hinge member 31 has twoarm members 33 extending toward thesecond hinge member 32, and each of thearm members 33 is integral, at its left-hand end, with thesecond hinge member 32 through aweb 34, the thin central portion of which defines afirst hinge line 36. Between the twowebs 34, thesecond hinge member 32 has a rigidupstanding extension 38, of which the upper portion is integral through aweb 40 with the left-hand end of a resilient connectinglink 42, of which the righthand end is rigidly integral with thefirst hinge member 31, as best seen in FIG. 6. Theweb 40 defines asecond hinge line 44, and thepoint 45 is the approximate point of attachment between thelink 42 and themember 31. The same expression for the opening or closing torque T applies for this embodiment as for the embodiment shown in FIGS. 1 to 4. The second embodiment of the hinge has not been shown in a position similar to FIG. 3, since the same configuration would result and the geometric considerations would be the same. FIG. '7 shows the second embodiment in the position corresponding to FIG. 4 for the first embodiment, and it will be appreciated again that, since thesecond hinge line 44 is located slightly to the left of thefirst hinge line 36, the resilient connectinglink 42 is still under some compression in the FIG. 7 position, and thus there will be a force tending to urge thehinge members 31 and 32 together in the FIG. 7 position.

In this second embodiment, it will be appreciated that the action of the resilient connectinglink 42 is at all times to place theweb 34 in tension. This is an advantage because if theweb 34 were in compression, there would be a danger of overlapping and shearing with repeated flexings.

FIGS. 8 and 9 show alternative designs for the resilient connectinglink 42. In FIG. 8, thelink 42 is slightly bowed concave upwardly in its unstressed position, and there is aweb 50 at the right-hand end as well as aweb 51 at the left-hand end where thelink 42 joins theprojection 38. FIG. 9 is similar to FIG. 8, except that the resilient connecting link is convex upwardly in its unstressed condition. Again, there is aweb 50 at the right'hand end of thelink 42, with aweb 51 at the lefthand end.

In the discussion that follows the snap-hinges shown in FIGS. 1 through 9 will be considered to have three parallel bending lines: line A, representing thelines 18 and 36; line B, representing thelines 28 and 45; and line C, representing thelines 26 and 44. The letters A, B and C are shown in FIGS. 2 and 6. For purposes of this description, bending lines A and B are located in the same initial horizontal plane. As pointed out earlier, the location of bending line C to the left of bending line A results in residual compressive stress in the resilient connecting link when the hinge is in the closed position, because mechanical interference between the first and the second hinge member prohibits rotation of the first hinge member to the other location of completely relieved compression bowing stress. The obvious advantage of clamping closure force between the hinge members results. FIGS. 4 and 7 illustrate this condition of rotation, mechanically stopped at 180 travel of the first hinge member.

It will be further realized that as bending line C is angularly displaced in the counter-clockwise direction, with bending lines A and B still in the same horizontal plane, a configuration will be arrived at wherein the first hinge member reaches closure (mechanical interference) just as the bending lines A, C and B become aligned (angle 4: zero). This configuration will be determined by the initial angulation of the hinge members and the location of the bending line C. These conditions describe an always open" compression hinge. Another way of putting it is to say that the first hinge member, because of mechanical interference, never goes beyond a position of unstable equilibrium.

Still further analysis of the positional relationship of the bending lines contemplated by this invention reveals that as bending line C moves clockwise and goes to the right of the vertical at the bending line A, it is possible to select specific values of angular travel between 0 and 180 for the first hinge member. Also, as C moves counter-clockwise to the left with respect to the vertical at bending line A, unstopped angular travel of the first hinge member will be greater than 180 and specific values between H and 360 may be selected. Unstopped angular travel is a hypothetical situation in which no mechanical interference between the two hinge members takes place. Bending line C, it will be noted, is always located on the bisector of the angle describing unstopped first hinge member travel. Assuming the moment of inertia and the modulus of elasticity of the connecting link to be known, spring force may also be computed.

It will thus be appreciated that, when the snap-hinge is formed in manufacture with the hinge members at a designated angular relationship, and rotation of the first hinge member is intended to bring the two hinge members together, it is possible to provide a predetermined closure force to be exerted by the connecting arm, by selecting the appropriate material and dimensions for the latter. Also, when the hinge members are formed at a designated angular relationship and rotation of the first hinge member brings it to only a portion of the initial angulation before it reaches an at-rest position, a determination of this second at-rest position can be made.

Those skilled in the art will appreciatethat in the event the two hinge members are formed with an angular relationship less than approximately 30 or more than 330, certain manufacturing complexities will be encountered in the webbed embodiment. Further, an initial angular relationship approaching zero as the limit is of little or no value as far as the purposes of this invention are concerned.

Turning now to FIGS. 10 and 1.1, there is shown one form of a third embodiment of this invention, in which the connecting link is adapted to undergo expansion as between its two ends. The hinge shown in FIGS. 10 and 11 is adapted for use with pipe insulation, which is usually available as two semi-cylindrical portions adapted to be clamped together around the pipe. Sometimes the two portions of insulation are joined along one edge by an outer skin bridging between the portions, such that the portions can hinge about that point. In other cases, the two portions are made separately, without any connection or hinge means between them. The hinge device shown in FIGS. 10 and 11 is adapted to be inserted into one end of a length of split insulation, with twoprongs 52 and 53 inserted into one portion of the insulation and twoprongs 54 and 55 inserted into the other portion thereof. Theprongs 52 and 53 project integrally from afirst hinge member 57, while theprongs 54 and 55 project integrally from asecond hinge member 58. As best seen in FIG. 11, the twohinge members 57 and 58 are integral with one another through aflexible web 60, which is considered to constitute a first hinge line. Bothhinge members 57 and 58 are moulded with a cross-section in the shape of a T, in order to give rigidity to themembers 57 and 58. The prongs 52-55 are slightly tapered and pointed, for ease of insertion into the insulation material, which is usually either fiberglass or cellular plastic. A connectinglink 62 of circular configuration is joined integrally at one end to thehinge member 57 through anintegral web 64 constituting a second hinge line, and is joined at the other end to thesecond hinge member 58 through a furtherintegral web 66 constituting a third hinge line. The connectinglink 62 has, as shown in FIG. 10, a roughly triangular cross-section, although this is not essential.

The position of the snap-hinge of FIG. with respect to the split pipe insulation with which it is used is shown in FIG. 11, in which the pipe insulation has been shown in broken lines. The snap-hinge is positioned with theweb 60 lying adjacent the intersection of theouter periphery 67 of the pipe insulation and thesplit line 68 between the twoportions 69 and 70 of the pipe insulation. The prongs 5255 are symmetrically arranged with respect to thesplit line 68, and inserted into the insulation material. The snap-hinge thus acts as a hinge between the twoportions 69 and 70, which articulate about theweb 60, while the connectinglink 62 serves as a spring tending to maintain the twoportions 69 and 70 in their closed position (that shown in broken lines in FIG. 1 l

If it were desired to have a positive closure force exerted on theportions 69 and 70 when they are in the closed position, thehinge members 57 and 58 would be spread apart to some extent before insertion of the prongs 52-55, such that the rectilinear distance between theprongs 52 and 55 is greater than the distance between them in the unstressed condition.

If the twoportions 69 and 70 of the pipe insulation, with the pronged snap-hinge of FIG. 10 inserted in one end as described above, were now to be gradually spread apart, articulating about theweb 60, the connectinglink 62 would be resiliently expanded, and would try to urge the two portions back together. If, however, the twoportions 69 and 70 were spread far enough apart that theprongs 52, 53, 54 and 55 were brought into line with one another, the force exerted by the connectinglink 62 would no longer urge theportions 69 and 70 together, since the snap-hinge would be in a state of unstable equilibrium. If theportions 69 and 70 were expanded beyond the position in which unstable equilibrium occurs, the connectinglink 62 would urge theportions 69 and 70 toward an open position.

Thus, by applying a snap-hinge of the type shown in FIG. 10 to the end of a length of split pipe insulation (or two: one at either end), the length of split pipe insulation would have a hold-closed and a hold-open position.

FIG. 13 shows, in cross-section, an extruded form of the third embodiment of this invention. The cross-section of the extrudate shown generally at 72 in FIG. 13 is composed of twoopposed portions 73 and 74 joined by a relativelythin portion 75 constituting a first web in the extrudate. Acurved portion 76 is joined to both of theopposed portions 73 and 74 at points spaced from thefirst web 75. Thecurved portion 76 is joined to theportion 73 through athin portion 78 constituting a second web in the extrudate, and is joined to theportion 74 through athin portion 80 constituting a third web in the extrudate. Thecurved portion 76 lies to one side of thehypothetical line 81 joining thesecond web 78 and thethird web 80. Thefirst web 75 lies on the other side of thehypothetical line 81 and is spaced therefrom. The characteristics described above are essential to a hold'open, hold-closed extruded snap-hinge in which the connecting link undergoes expansion. As can be seen, thecurved portion 76 has a circular curvature, although this is not essential. What is essential is that the straightened length of thecurved portion 76 be at least as long as the sum of the rectilinear distance between thefirst web 75 and thesecond web 78 plus the rectilinear distance between thefirst web 75 and thethird web 80. Otherwise the hinge would not be a snap-hinge, because thecurved portion 76 would be incapable of sufficient expansion to permit the first, second andthird webs 75, 78 and 80 to become aligned. It will be understood that this position of alignment will constitute the state of unstable equilibrium for the snap-hinge, without which the hinge would be able to maintain only one position. The straightened length of thecurved portion 76 will lie somewhere between the length of the inside are 82 and the length of the outside are 83.

FIGS. 14 and 15 show the extruded snap-hinge in, respectively, an intermediate hinged position, and the closed position in which theportions 73 and 74 are closed against one another. It will be noted that, in FIG.

' 14, thecurved portion 76 is expanded to a radius of curvature greater than that which it has in either FIG. 13 or FIG. 15.

Theopposed portions 73 and 74 are each equipped with aslot 84 capable of receiving and gripping an appropriate plate-like element, the two plate-like elements so gripped being snap-hinged together by the extruded snap-hinge about theweb 75.

The method according to this invention involves the steps of extruding an integral extrudate from stiff but resilient material such as polypropylene, which extrudate has a cross-section meeting the criteria set out above, and cutting the extrudate transversely to obtain a section thereof.

FIG. 16 shows a special form of the first embodiment of this invention. Only thefirst hinge member 86 is shown. Thehinge member 86 has two spaced-apartarms 87 supporting outwardly projecting pivot pins 88 at their extremities. Between thearms 87 is a connectinglink 90 which has two opposed, aligned pivot pins 91 at its end. The connectinglink 90 is thinner than thearms 87, such that the connectinglink 90 is resilient by comparison with thearms 87. Thehinge member 86 is adapted to be pivotally connected to another rigid hinge member (not shown) through the pivot pins 88, the common axis of which constitutes the first bending line A. The connectinglink 90 is also adapted to be pivotally connected to the other rigid hinge member through the pivot pins 91, the common axis of which constitutes the third bending line C. The line B in FIG. 16 represents the approximate point of attachment between the connectinglink 90 and thehinge member 86 and is considered to be the second bending line of the hinge. In the at-rest position the lines A, B and C are in alignment, with A intermediate B and C. This arrangement gives a 360 hinge configuration, in which the connectinglink 90 begins to undergo compression as soon as the hinge member86 begins to pivot with respect to the other hinge member, regardless of the direction of pivoting. It will be appreciated that this hinge configuration has only one at-rest position, and that the position of unstable equilibrium arises at 180 displacement from the atrest position.

Turning now to FIG. 17, the first variant of the fourth embodiment of this invention is seen to include afirst hinge member 94, a split biasing member consisting of twoportions 95a and 95b, and a second hinge member consisting of afirst part 96 and asecond part 98. In one application of the fourth embodiment of this invention, theparts 96 and 98 constitute, respectively, the two free ends of a split sealing ring adapted to close the periphery of tape reels against the entry of dust and other foreign material. These sealing rings, and the tape reels with which they are used, are widely employed in the data-processing field. Thus, while the following description assumes that theparts 96 and 98 are distinct, separate items, this does not preclude an arrangement wherein the two parts are linked remotely, as in a circular sealing ring of the above type.

Attention is now directed specifically to thepart 96, which consists of abase portion 100, and a surmountingportion 102. Thebase portion 100 is a flat, bandlike, elongated element having twoparallel grooves 104 which are adapted to receive the peripheries of the two circular plates constituting a tape reel (not shown). The surmountingportion 102 can be either formed integrally with thebase portion 100, or affixed thereto by some other conventional means, such as glueing, welding, or mechanical attachment. The surmountingportion 102 consists essentially of a block-like element 105 to which theportions 95a and 95b of the biasing element are hingedly connected alongintegral webs 106 which are collinear. As is evident in FIG. 17, the twoportions 95a and 95b of the biasing element are spaced apart, and the block-like element 105 has, between theportions 95a and 95b, agroove 108 of which the purpose will presently be explained.

Thepart 98 consists of abase portion 110 which is identical in cross-section to thebase portion 100 of thepart 96, surmounted by alocking element 112. Again, the lockingelement 112 can be either formed integrally with thebase portion 110, or affixed thereto by means of glue, welding, mechanical attachment, etc. The lockingelement 112 consists of alower portion 114, and anupstanding portion 116. The breadth of theupstanding element 116 is less than the lateral distance between theportions 95a and 95b of the biasing element, such that theportions 95a and 95b can lie on either side of theupstanding portion 116. Theportion 116 defines agroove 117 opening remotely from thepart 96. Integral with theupstanding portion 116 is ahorizontal protuberance 118 which is adapted for complementary engagement with thegroove 108.

It will be appreciated that, while in the embodiment shown, thebase portions 100 and 110 have identical cross-sections, this is due merely to the particular application of the fourth embodiment to the two free ends of a split sealing ring. Obviously, thebase portions 100 and 110 could be replaced with any other abutting members.

Thefirst hinge member 94 has atongue 120 extending therefrom between the portions a and 95b of the biasing element.

FIGS. 18 to 20 show sequential steps in the operation of locking the twoparts 96 and 98 together by means of the biased hinge. FIG. 18 shows the two base portions and abutting one another, with theprotuberance 118 lodged in thegroove 108. When this complementary abutment has taken place, it is then possible to swing thefirst hinge member 94 downwardly so that theend 121 of the tongue projecting from thehinge member 94 can lodge inside thegroove 117 to create a hinge axis between thefirst hinge member 94 and thepart 98 of the second hinge member. It is considered that the twoparts 96 and 98 of the second hinge member canbe taken as a single member when they are in the abutting relationship shown in FIGS. 18 to 20. Thus, it is permissible to speak of a hinging relation between thefirst hinge member 94 and the second hinge member (parts 96 and 98) when thetongue 120 is lodged in thegroove 117.

FIG. 19 shows thefirst hinge member 94 after it has been rotated in the clockwise direction to the point of unstable equilibrium, which arises when the twopoints 123 and 124, representing the hinge lines along which the biasing element 95 is attached to the surmountingportion 102 and to thefirst hinge member 94 respectively, are aligned with thepoint 126, the latter representing the line along which thetongue 120 bears against the surface of thegroove 117, thereby defining an instantaneous axis of rotation of thefirst hinge member 94 with respect to the second hingemember comprising parts 96 and 98.

The design of the biasingportions 95a and 95b is such that they are in a state of longitudinal tension in the over-toggling position of unstable equilibrium shown in FIG. 19. Although actual stretching in the biasingportions 95a and 95b is minimal, the integral web connection between the biasingportions 95a and 95b and both the surmountingportion 102 and thefirst hinge member 94 will stretch or deform to a larger degree. It is important, of course, so to design thebiasing members 95a and 95b that the webs aforementioned will not be stretched to rupture.

Further clockwise rotation of thehinge member 94 with respect to the composite hingemember comprising parts 96 and 98 will bring thefirst hinge member 94 to the FIG. 20 position, in which the hypotheticalline joining points 123 and 124 has gone past thepoint 126. It will be apparentthat, in the FIG. 20 position, the stress in the biasingportions 95a: and 95b will be less than in the FIG. 19 position, and this situation will en- I sure that thefirst hinge member 94 remains biased to the FIG. 20 position. Thus, the residual tension in the biasingportions 950 and 95b will hold the twoparts 96 and 98 in a tightly abutting relationship.

Another variant of the fourth embodiment of this invention is shown in FIGS. 21 and 22, in which it will be noted that the twoportions 130a and 13% of the biasingelement 130 are curved in the vertical plane. The other elements are similar to those of FIGS. 17 to 20, and include afirst hinge member 131, a second hinge member consisting of afirst part 133 and asecond part 134, thepart 134 being affixed to or integral with agrooved portion 136 which has afirst groove 137 in which therounded end 138 of thefirst part 133 is adapted to lodge, and asecond groove 140 in which thetongue 142 of thefirst hinge member 131 is adapted to be received. It will be appreciated that thecurved biasing portions 130a and 13% are capable of absorbing a greater deflection under tension than is the case with thestraight biasing portions 95a and 95b in FIGS. 17 to 20. For this reason, the dimensional design criteria in the variant shown in FIGS. 21 and 22 are not so critical.

In the variant shown in FIGS. 17 to 20, the hinge axis denoted by thepoint 126 is analogous to the hinge represented by theweb 75 in FIG. 13, the hinge axis denoted by thepoint 124 is analogous to the hinge represented by theweb 78 in FIG. 13, and the hinge axis denoted by thepoint 123 is analogous to the hinge represented by theweb 80 in FIG. 13.

It will be evident that the same over-toggling considerations hold for the second variant shown in FIGS. 21 and 22 as for the first variant shown in FIGS. 17 to 20. It is not considered necessary to show the hinge axes in the second variant of the fourth embodiment.

It will be appreciated that the fourth embodiment of this invention lends itself to integral moulding techniques, such that theelement 112 could be moulded integrally with thesecond part 98, and such that thefirst hinge member 94, the biasingportions 95a and 95b and the surmountingportion 102 could all be formed integrally with thefirst part 96.

In the appended claims, the word hinged is intended to cover both an integral web hinge and a hinge employing a pivot pin. The word pivoted is to be construed as covering only those hinge arrangements in which some sort of pivot pin is utilized. Pivoted does not include an integral web hinge. The term hingedly integral describes the flexible web connection which is shown in FIGS. 8 and 9 between the connectinglink 42 and both hinge members. The term rigidly integral" describes the non-flexible connection which is shown in FIG. 2 between the connecting link and the first hinge member 1 1.

While preferred embodiments of this invention have been disclosed herein, those skilled in the art will appreciate that changes and modifications may be made therein without departing from the spirit and scope of this invention as defined in the appended claims.

What I claim as my invention is:

1. A snap-hinge comprising:

a first hinge member,

a second hinge member hinged to said first hinge member about a first hinge line,

a curved resilient connecting link of uniform crosssection joined at one end integrally to said first hin'ge member at a second hinge line and joined at the other end integrally to said second hinge member at a third hinge line, the resilient connecting link tending resiliently to maintain its two ends apart at a given spacing, said second hinge line being spaced at an invariable distance from said first hinge line, said third hinge line being spaced at an invariable distance from said first hinge line, the snap-hinge having a first position and a second position, in each of which stress in the connecting link is at a minimum, the snap-hinge being at rest in each of said positions, a small departure from either of which increases the stress in the connecting link, which tends to restore the snap-hinge to the respective position, the connecting link being capable of resilient expansion between its one end and its other end, the snap-hinge being adapted to articulate between said first-mentioned position and said second position in such a way that the connecting link is resiliently expanded in positions intermediate said first-mentioned position and said second position, the maximum expansion of said connecting link representing a state of unstable equilibrium for the snap-hinge, departure from which in either direction causes said connecting link to urge the snap-hinge further in that direction to return the snap-hinge to one of said positions.

2. A snap-hinge as claimed in claim 1, in which said second hinge line and said third hinge line are equidistant from said first hinge line.

3. A snap-hinge as claimed in claim 1, in which said first hinge member is integral with said second hinge member through a flexible web defining said first hinge line, in which said one end of said resilient connecting link is integral with said first hinge member through a flexible web defining said second hinge line, and in which said other end of said resilient connecting link is integral with said second hinge member through a flexible web defining said third hinge line.

4. A snap-hinge as claimed in claim 3, in which said first and second hinge members and said resilient connecting link are made of a thermoplastic material.

5. A snap-hinge as claimed in claim 4, in which said thermoplastic material is polypropylene.

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Claims (5)

1. A snap-hinge comprising: a first hinge member, a second hinge member hinged to said first hinge member about a first hinge line, a curved resilient connecting link of uniform cross-section joined at one end integrally to said first hinge member at a second hinge line and joined at the other end integrally to said second hinge member at a third hinge line, the resilient connecting link tending resiliently to maintain its two ends apart at a given spacing, said second hinge line being spaced at an invariable distance from said first hinge line, said third hinge line being spaced at an invariable distance from said first hinge line, the snap-hinge having a first position and a second position, in each of which stress in the connecting link is at a minimum, the snap-hinge being at rest in each of said positions, a small departure from either of which increases the stress in the connecting link, which tends to restore the snap-hinge to the respective position, the connecting link being capable of resilient expansion between its one end and its other end, the snap-hinge being adapted to articulate between said first-mentioned position and said second position in such a way that the connecting link is resiliently expanded in positions intermediate said firstmentioned position and said second position, the maximum expansion of said connecting link representing a state of unstable equilibrium for the snap-hinge, departure from which in either direction causes said connecting link to urge the snap-hinge further in that direction to return the snap-hinge to one of said positions.

2. A snap-hinge as claimed in claim 1, in which said second hinge line and said third hinge line are equidistant from said first hinge line.

3. A snap-hinge as claimed in claim 1, in which said first hinge member is integral with said second hinge member through a flexible web defining said first hinge line, in which said one end of said resilient connecting link is integral with said first hinge member through a flexible web defining said second hinge line, and in which said other end of said resilient connecting link is integral with said second hinge member through a flexible web defining said third hinge line.

4. A snap-hinge as claimed in claim 3, in which said first and second hinge members and said resilient connecting link are made of a thermoplastic material.

5. A snap-hinge as claimed in claim 4, in which said thermoplastic material is polypropylene.

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