Biased hinges

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 deformation 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

This application is a continuation-in-part of U.S. application, Ser. No. 689,390, "Improvements in Biased Hinges," filed Dec. 11, 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 deformation 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 two prongs 52 and 53 inserted into one portion of the insulation and two prongs 54 and 55 inserted into the other portion thereof. The prongs 52 and 53 project integrally from a first hinge member 57, while the prongs 54 and 55 project integrally from a second hinge member 58. As best seen in FIG. 11, the two hinge members 57 and 58 are integral with one another through a flexible web 60, which is considered to constitute a first hinge line. Both hinge members 57 and 58 are moulded with a cross-section in the shape of a "T," in order to give rigidity to the members 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 connecting link 62 of circular configuration is joined integrally at one end to the hinge member 57 through an integral web 64 constituting a second hinge line, and is joined at the other end to the second hinge member 58 through a further integral web 66 constituting a third hinge line. The connecting link 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. 10 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 the web 60 lying adjacent the intersection of the outer periphery 67 of the pipe insulation and the split line 68 between the two portions 69 and 70 of the pipe insulation. The prongs 52-55 are symmetrically arranged with respect to the split line 68, and inserted into the insulation material. The snap-hinge thus acts as a hinge between the two portions 69 and 70, which articulate about the web 60, while the connecting link 62 serves as a spring tending to maintain the two portions 69 and 70 in their closed position (that shown in broken lines in FIG. 11).

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

If the two portions 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 the web 60, the connecting link 62 would be resiliently expanded deformed, and would try to urge the two portions back together. If, however, the two portions 69 and 70 were spread far enough apart that the prongs 52, 53, 54 and 55 were brought into line with one another, the force exerted by the connecting link 62 would no longer urge the portions 69 and 70 together, since the snap-hinge would be in a state of unstable equilibrium. If the portions 69 and 70 were expanded beyond the position in which unstable equilibrium occurs, the connecting link 62 would urge the portions 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 two opposed portions 73 and 74 joined by a relatively thin portion 75 constituting a first web in the extrudate. A curved portion 76 is joined to both of the opposed portions 73 and 74 at points spaced from the first web 75. The curved portion 76 is joined to the portion 73 through a thin portion 78 constituting a second web in the extrudate, and is joined to the portion 74 through a thin portion 80 constituting a third web in the extrudate. The curved portion 76 lies to one side of the hypothetical line 81 joining the second web 78 and the third web 80. The first web 75 lies on the other side of the hypothetical 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 deformation. As can be seen, the curved portion 76 has a circular curvature, although this is not essential. What is essential is that the straightened length of the curved portion 76 be at least as long as the sum of the rectilinear distance between the first web 75 and the second web 78 plus the rectilinear distance between the first web 75 and the third web 80. Otherwise the hinge would not be a "-snap-hinge," because the curved portion 76 would be incapable of sufficient expansion deformation to permit the first, second and third 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 the curved portion 76 will lie somewhere between the length of the inside arc 82 and the length of the outside arc 83.

FIGS. 14 and 15 show the extruded snap-hinge in, respectively, an intermediate hinged position, and the closed position in which the portions 73 and 74 are closed against one another. It will be noted that, in FIG. 14, the curved portion 76 is expanded deforms to a radius of curvature greater than that which it has in either FIG. 13 or FIG. 15.

The opposed portions 73 and 74 are each equipped with a slot 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 the web 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 the first hinge member 86 is shown. The hinge member 86 has two spaced-apart arms 87 supporting outwardly projecting pivot pins 88 at their extremities. Between the arms 87 is a connecting link 90 which has two opposed, aligned pivot pins 91 at its end. The connecting link 90 is thinner than the arms 87, such that the connecting link 90 is resilient by comparison with the arms 87. The hinge 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 connecting link 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 connecting link 90 and the hinge 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 connecting link 90 begins to undergo compression as soon as the hinge member 86 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 "at-rest" position.

Turning now to FIG. 17, the first variant of the fourth embodiment of this invention is seen to include a first hinge member 94, a split biasing member consisting of two portions 95a and 95b, and a second hinge member consisting of a first part 96 and a second part 98. In one application of the fourth embodiment of this invention, the parts 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 the parts 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 the part 96, which consists of a base portion 100, and a surmounting portion 102. The base portion 100 is a flat, band-like, elongated element having two parallel grooves 104 which are adapted to receive the peripheries of the two circular plates constituting a tape reel (not shown). The surmounting portion 102 can be either formed integrally with the base portion 100, or affixed thereto by some other conventional means, such as glueing, welding, or mechanical attachment. The surmounting portion 102 consists essentially of a block-like element 105 to which the portions 95a and 95b of the biasing element are hingedly connected along integral webs 106 which are collinear. As is evident in FIG. 17, the two portions 95a and 95b of the biasing element are spaced apart, and the block-like element 105 has, between the portions 95a and 95b, a groove 108 of which the purpose will presently be explained.

The part 98 consists of a base portion 110 which is identical in cross-section to the base portion 100 of the part 96, surmounted by a locking element 112. Again, the locking element 112 can be either formed integrally with the base portion 110, or affixed thereto by means of glue, welding, mechanical attachment, etc. The locking element 112 consists of a lower portion 114, and an upstanding portion 116. The breadth of the upstanding element 116 is less than the lateral distance between the portions 95a and 95b of the biasing element, such that the portions 95a and 95b can lie on either side of the upstanding portion 116. The portion 116 defines a groove 117 opening remotely from the part 96. Integral with the upstanding portion 116 is a horizontal protuberance 118 which is adapted for complementary engagement with the groove 108.

It will be appreciated that, while in the embodiment shown, the base 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, the base portions 100 and 110 could be replaced with any other abutting members.

The first hinge member 94 has a tongue 120 extending therefrom between the portions 95a and 95b of the biasing element.

FIGS. 18 to 20 show sequential steps in the operation of locking the two parts 96 and 98 together by means of the biased hinge. FIG. 18 shows the two base portions 100 and 110 abutting one another, with the protuberance 118 lodged in the groove 108. When this complementary abutment has taken place, it is then possible to swing the first hinge member 94 downwardly so that the end 121 of the tongue 120 projecting from the hinge member 94 can lodge inside the groove 117 to create a hinge axis between the first hinge member 94 and the part 98 of the second hinge member. It is considered that the two parts 96 and 98 of the second hinge member can be 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 the first hinge member 94 and the second hinge member (parts 96 and 98) when the tongue 120 is lodged in the groove 117.

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

The design of the biasing portions 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 biasing portions 95a and 95b is minimal, the integral web connection between the biasing portions 95a and 95b and both the surmounting portion 102 and the first hinge member 94 will stretch or deform to a larger degree. It is important, of course, so to design the biasing members 95a and 95b that the webs aforementioned will not be stretched to rupture.

Further clockwise rotation of the hinge member 94 with respect to the composite hinge member comprising parts 96 and 98 will bring the first hinge member 94 to the FIG. 20 position, in which the hypothetical line joining points 123 and 124 has gone past the point 126. It will be apparent that, in the FIG. 20 position, the stress in the biasing portions 95a and 95b will be less than in the FIG. 19 position, and this situation will ensure that the first hinge member 94 remains biased to the FIG. 20 position. Thus, the residual tension in the biasing portions 95a and 95b will hold the two parts 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 two portions 130a and 130b of the biasing element 130 are curved in the vertical plane. The other elements are similar to those of FIGS. 17 to 20, and include a first hinge member 131, a second hinge member consisting of a first part 133 and a second part 134, the part 134 being affixed to or integral with a grooved portion 136 which has a first groove 137 in which the rounded end 138 of the first part 133 is adapted to lodge, and a second groove 140 in which the tongue 142 of the first hinge member 131 is adapted to be received. It will be appreciated that the curved biasing portions 130a and 130b are capable of absorbing a greater deflection under tension than is the case with the straight 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 the point 126 is analogous to the hinge represented by the web 75 in FIG. 13, the hinge axis denoted by the point 124 is analogous to the hinge represented by the web 78 in FIG. 13, and the hinge axis denoted by the point 123 is analogous to the hinge represented by the web 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 the element 112 could be moulded integrally with the second part 98, and such that the first hinge member 94, the biasing portions 95a and 95b and the surmounting portion 102 could all be formed integrally with the first 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 connecting link 42 and both hinge members. The term "rigidly integral" describes the non-flexible connection which is shown in FIG. 2 between the connecting link 20 and the first hinge member 11.

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.

Claims

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 invarible 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.

6. 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, the link being 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 link being curved and said ends of substantially uniform cross-section intermediate its ends, the resilient connection 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 deformation between its one end and its other end when the distance between the ends changes, 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 deformed in positions intermediate said first-mentioned position and said second position when the distance between the ends of the link changes, the maximum deformation 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.

7. A snap-hinge as claimed in claim 6, 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.

8. The snap-hinge as claimed in claim 6, wherein when said snap-hinge is in the rest position, the distance between the second hinge line and the third hinge line is less than the distance at which the maximum stress exists in the connecting link.

9. A snap-hinge as claimed in claim 8 wherein as the snap-hinge proceeds from the first position to the second, the distance between the second hinge line and the third hinge line increases, deforming said connecting link with said deformation continuing until a maximum point is reached, prior to reaching this maximum point the first hinged member is biased towards the first position, after exceeding this maximum point the distance between the second hinge line and the third hinge line decreases and the first hinge member is biased towards the second position, eventually realizing said position. 10. A snap-hinge as claimed in claim 8, wherein as the snap-hinge proceeds from the second position to the first position, the distance between the second hinge line and the third hinge line increases, deforming said connecting link with said deformation continuing until a maximum point is reached, prior to reaching this maximum point the first hinge member is biased towards the second position, after exceeding the maximum point the distance between the second hinge line and the third hinge line decreases and the first hinge member is biased towards the first position, eventually realizing said position.

11. A snap hinge as claimed in claim 6 wherein said resilient connecting link is curved throughout its entire length.

12. A snap hinge as claimed in claim 6 wherein said resilient connecting link is of uniform cross-section throughout its entire length.

13. A snap-hinge as claimed in claim 6, in which said second hinge line and said third hinge line are equidistant from said first hinge line.

14. A snap-hinge as claimed in claim 7, in which said first and second hinge members and said resilient connecting link are made of a thermoplastic material.

15. A snap-hinge as claimed in claim 13, in which said thermoplastic material is polypropylene.