Pin Hinge

Abstract

A snap hinge which includes a plate member pivoted to a rigid member. Extending from the plate member at a location spaced from the first pivot is a resilient arm the end of which is integral through a flexible web with a connecting arm. The other end of the connecting arm is pivoted to the rigid member at a point spaced from the plate member pivot. Depending on the distance between the pivots, the snap hinge has either one or two at-rest positions.

Description

This invention relates to biased hinges, or "snap-hinges" as they are sometimes called, in which the hinge tends to hold itself in either the closed position or the open position, or both positions.

The object of this invention is to provide a two-part, biased hinge in which the biasing structure is incorporated integrally into one of the two parts, the other of the two parts being merely a rigid member.

Accordingly, this invention provides a snap hinge comprising: a plate member having a first pivot, a resilient arm integral with said plate member and extending therefrom at a location spaced from said first pivot, the resilient arm tending to seek an unstressed position with respect to said plate member, a connecting arm integral through a flexible web with a portion of the resilient arm spaced from the plate member, said connecting arm having a second pivot remote from said flexible web, said web portion constituting a hinge axis which is space d from said first pivot when said resilient arm is in said unstressed position.

Two embodiments of the present invention are shown in the accompanying drawings, in which like numerals refer to like parts throughout the several views, and in which:

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

FIGS. 2, 3, 4 and 5 are sectional views, taken at the line A-A of FIG. 1, showing sequential rotational positions of the first embodiment of this invention; and

FIGS. 6, 7, 8 and 9 are sectional views, similar to FIGS. 2 to 5, of the second embodiment of this invention.

Turning first to FIG. 1, the first embodiment of this invention is seen to include a first part 10 and a second part 11. The first part 10 consists of a plate member 12, which is shown to be substantially in the shape of a tuning fork, although any other suitable shape can be used. The plate member 12 thus has two arms 14 and a base 16. The plate member 12 has a first pivot 18 defined by two integral, aligned bosses 20, one projecting outwardly from either arm 14. Integral with the plate member 12 and extending from the plate member between its two arms 14 is a resilient arm 22. The resilient arm 22 extends from the plate member 12 at a location 23 spaced rightwardly from the pivot 18, and is constructed such that it tends to seek an unstressed position with respect to the plat member 12, this unstressed position being shown in dotted lines in FIG. 2. In the latter Figure it will be noted that the resilient arm 22 in its unstressed position forms an acute angle with hypothetical line extending between the pivot 18 and the location 23 at which the resilient arm extends from the plate member 12.

A connecting arm 25 is integral with the resilient arm 22 through a flexible web 26. The flexible web 26 is remote from the location 23 at which the resilient arm 22 extends from the plate member 12, and constitutes a hinge axis between arms 22 and 25.

The connecting arm 25 has a pivot 28 at its end remote from the flexible web 26, and the pivot 28 is define by two cylindrical extensions 30, one projecting from either side of the connecting arm 25.

In FIG. 1, the second part of the hinge has been shown as a single, rigid disc 32 having a central aperture 33 and a plurality of eccentric apertures 34 all equidistant from the central aperture 33. The second part 11 actually consists of two such discs 32, but the nearer one has not been shown, in order to permit the structure of the first part 10 to be viewed. The bosses 20 are adapted to enter the apertures 33 in the discs 32, and the cylindrical extensions 30 are adapted to lodge in particular ones of the eccentric apertures 34 of the discs 32. The discs 32 are identical, and they are fixed with respect to each other in such a way that the apertures 33 and 34 correspond in pairs and are coaxial.

The ends of the arms 14 have curved seating portions 36 which are adapted to rest against the extensions 30 and thereby provide a limit to the counterclockwise rotation of the plate member 12 about the pivot 18. The limit-providing property of the curved portions 36 is best seen in FIG. 2. When the plate member 12 is in the FIG. 2 position, and the bosses 20 and projections 30 are lodged in appropriate apertures 33 and 34, the length of the connecting arm 25 and the distance between the apertures 33 and 34 are such that the resilient arm 22 is flexed to some degree toward the bosses 20. The degree of flexure is that between the dotted line and solid line positions of the resilient arm 22 in FIG. 2. Thus, when the plate member 12 is in the FIG. 2 position, the resilient arm 22 is pulling upwardly and rightwardly on the pivot 28 through the medium of the connecting arm 25. This slight tension of the resilient arm 22 tends to maintain the plate member 12 in the FIG. 2 position, and can be said to bias the plate member 12 to the FIG. 2 position.

Attention is now directed to the sequential FIGS. 2, 3, 4 and 5, in which the biasing action of the first embodiment of this invention is shown. The first embodiment of this invention is one wherein the plate member 12 is adapted to be biased into two positions, the first one being that shown in FIGS. 1 and 2, the second position being that shown in FIG. 5, which is almost 180.degree. rotated from the position of FIG. 2. The plate member 12 is pivoted to the discs 32 about the pivot 18, and downward pressure on the base 16 of the plate member 12 will begin to rotate the plate member in the clockwise direction about the pivot 18. FIG. 3 shows the plate member 12 rotated approximately 60.degree. clockwise from the position in FIG. 2. It will be noted that the resilient arm 22 is flexed further toward the pivot 18 in FIG. 3 than it is in FIG. 2.

Attention is now directed to the line 40 which is the hypothetical line along which tension in the connecting arm 25 is directed. It will be noted that, in FIG. 2, the line 40 lies well away to one side of the pivot 18. As the plate member 12 reaches the FIG. 3 position, the hypothetical line 40 moves closer to the pivot 18, but still remains on the same side of the latter. Because the line 40 is still on the same side of the pivot 18, the effect of the spring action in the resilient arm 22 will remain one of biasing the plate member counterclockwise towards the FIG. 2 position. It will be noted however, that when the plate member 12 reaches the FIG. 4 position, the hypothetical line 40 is coincident with the pivot 18, and it is in this position that the biasing action of the resilient arm 22 is completely nullified. In effect, when the plate member 12 reaches the FIG. 4 position, it is in a state of unstable equilibrium. If the plate member 12 is now moved further in the clockwise direction, the line 40 will pass to the other side of the pivot 18, and the effect of this will be to bias the plate member 12 towards the FIG. 5 position, where the resilient arm 22 and the connecting arm 25 are in contact to establish a clockwise limit to the rotation of the plate member 12. It will be noted that the resilient arm 22 is flexed the most when the hypothetical line 40 coincides with the pivot 18 in FIG. 4, and that the resilient arm 22 comes back some distance in FIG. 5 towards its unstressed position (dotted lines in FIG. 2).

It is considered that the principal criterion which determines that the hinge will function in the way just described with reference to FIGS. 2 to 5 is that the discs 32 maintain the pivot 18 separated from the pivot 28 by a distance which is less than the distance between the pivot 28 and the web 26, i.e., the interpivot distance is less than the effective length of the connecting arm 25.

The operation of the hinge when the length of the connecting arm 25 is less then the distance between the pivots 18 and 28 is shown in FIGS. 6 to 9, and this constitutes the second embodiment of this invention. The second embodiment is one which is only biased in one direction, and which never reaches the null point beyond which it is biased in the other direction. Looking first at FIG. 6, the unstressed position for the resilient arm 22 is again shown in dotted lines, the plate member 12 is again adapted to pivot about the pivot 18, the connecting arm 25 (visibly shorter than the distance between the pivots 18 and 28) is again integral with the resilient arm 22 through a web portion 26, and tension in the connecting arm 25 is exerted along a hypothetical line 40. As the plate member 12 is rotated in the clockwise direction about the pivot 18, it reaches the FIG. 7 position. It will be noted that the resilient arm 22 is more greatly flexed in FIG. 7 than in FIG. 6, and that the hypothetical line 40 remains on the same side of the pivot 18. Further rotation of the plate member 12 brings it to the FIG. 8 position, in which the resilient arm 22 is flexed completely across to the other side of the plate member 12, and that the hypothetical line 40 is still on the same side of the pivot 18. Further rotation brings the plate member 12 to the FIG. 9 position, where the resilient arm 22 is very greatly stressed, the hypothetical line 40 still remaining on the same side of the pivot 18. Because the hypothetical line 40 never crosses the pivot 18, the plate member 12 is always biased in the counterclockwise direction with respect to the discs 32, with a biasing effect which grows greater with every degree of clockwise rotation of the plate member 12, due to the increasing flexure of the arm 22.

The first and second embodiments of this invention can be compared in terms of moment arms by considering that the discs 32 are exerting a leftward force on the projections 30 along the hypothetical line 40, and that this leftward force along the line 40 is transmitted to the entire plate member through the resilient arm 22. The moment arm at any given point is the product of the perpendicular distance from the pivot 18 to the line 40 and the force exerted by the connecting arm 25 on the discs 32. As the plate member reaches the FIG. 3 position, the force has increased due to the greater flexing of the arm 22, but the perpendicular distance from the pivot 18 to the line 40 has decreased, so that their produce may be greater or smaller than in FIG. 2. In FIG. 4, however, the distance from the pivot 18 to the line 40 is zero, so that the moment arm itself is zero, which gives rise to the unstable equilibrium described above. In FIG. 5, the pivot 18 is again a finite distance from the line 40, and a moment arm is thereby created. However, since the line 40 is now on the other side of the pivot 18, the sense of the moment arm will change. In the second embodiment, shown in FIGS. 6 to 9, since the line 40 never crosses the pivot 18, the moment arm never changes direction, and the plate member 12 is always biased in the counterclockwise direction about the pivot 18.

By using the first embodiment of this invention, and by slightly altering certain portions of the assembly, there can be provided an "on-off" switch in which the "on" position can be selected from a number of radial positions around the discs 32. As shown in FIG. 1, the connecting arm 25 is forked in such a way that the projections 30 can be moved toward one another under pressure. The outer ends of the projections 30 are made hemispherical, and the apertures 34, equally spaced from the aperture 33, are replaced by hemispherical depressions. Thus, when the plate member 12 and the two discs 32 are assembled, the bosses 20 engage, as before, the apertures 33, but the projections 30 are wedged into a pair of hemispherical depressions 34. The projections 30 can be moved from any given pair of hemispherical depressions to the next adjacent pair of hemispherical depressions merely by applying pressure at the end of the base 16 of the plate member 12. For example, when the assembly is in the situation of FIG. 2, the projections 30 can be moved to the next counterclockwise pair of hemispherical depressions by exerting pressure upwardly on the rightward end of the base 16 of the plate member 12. When the plate member is in the FIG. 5 position, the projections 30 can be moved to the next clockwise pair of hemispherical depressions by pushing upwardly on the outer (now leftward) end of the plate member 12.

It will be appreciated that the elements of the hinge assembly herein disclosed do not need to be identical to those shown. In particular, the discs 32 can be replaced by a single plate member having sockets into which the bosses 20 and the projections 30 can be received.

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

What I claim as my invention is:

1. A snap-hinge comprising:

a plate member,

a rigid member to which the plate member is pivotally mounted by a first pin-and-socket connection defining a first pivot axis,

a resilient arm integral with said plate member and extending therefrom at a location spaced from said first pivot axis, the resilient arm tending to seek a given position with respect to said plate member,

a connecting arm integral through a flexible web with a portion of the resilient arm spaced from the plate member,

said connecting arm being pivotally mounted to said rigid member at a location remote from said flexible web by a second pin-and-socket connection defining a second pivot axis,

said web constituting a hinge axis which is spaced from said first pivot axis when said resilient arm is in said given position,

the rigid member maintaining said first pivot axis separated from said second pivot axis by a distance which is less than the distance between said second pivot axis and said hinge axis.

2. A snap hinge as claimed in claim 1, in which said resilient arm in said given position defines an acute angle with the hypothetical line joining said first pivot axis and said location.

3. A snap hinge as claimed in claim 2, in which said plate member, said resilient arm and said connecting arm are made of polypropylene.

4. A snap hinge as claimed in claim 2, in which said plate member has at least one cylindrical pin projecting therefrom at each pivot axis, the rigid member having socket-defining means for receiving all cylindrical pins.

5. A snap-hinge comprising:

a plate member,

a rigid member to which the plate member is pivotally mounted by a first pin-and-socket connection defining a first pivot axis,

a resilient arm integral with said plate member and extending therefrom at a location spaced from said first pivot axis, the resilient arm tending to seek a given position with respect to said plate member,

a connecting arm integral through a flexible web with a portion of the resilient arm spaced from the plate member,

said connecting arm being pivotally mounted to said rigid member at a location remote from said flexible web by a second pin-and-socket connection defining a second pivot axis,

said web constituting a hinge axis which is spaced from said first pivot axis when said resilient arm is in said given position,

the rigid member maintaining said first pivot axis separated from said second pivot axis by a distance which is greater than the distance between said second pivot axis and said hinge axis.

6. A snap hinge as claimed in claim 5, in which said resilient arm in said given position defines an acute angle with the hypothetical line joining said first pivot axis and said location.

7. A snap hinge as claimed in claim 6, in which said plate member, said resilient arm and said connecting arm are made of polypropylene.

8. A snap hinge as claimed in claim 6, in which said plate member has at least one cylindrical pin projecting therefrom at each pivot axis, the rigid member having socket-defining means for receiving all cylindrical pins.