GB2325490A - Frictional Hinge. - Google Patents

Abstract

A hinge mechanism comprises a hinge pin 1 which is supported at each end by members 3 and 4, and is located inside a hollow tube 2 of polygonal cross section. The tube 2 and members 3/4 rotate relative to each other to form the hinge, the tube being attached to a shelving member, for example. Pin 1 is flexible and has a central offset section that engages the inner wall of the tube. Rotation of the tube causes the pin to flex and frictionally engage with the tube, effectively 'locking' the hinge in positions where the pin engages the corner of the tube interior. In alternative embodiments, the hinge pin may be straight, having a cam (19, Figure 5) to engage the tube, or the pin may have multiple bend sections (Figure 7). The hinge has particular application to foldable shelving, such as found in roll pallets used in supermarkets and warehouses.

Description

"A Hinge Mechanism" The invention relates to a hinge mechanism, and in particular, but not exclusively, a hinge mechanism for a shelf which is pivotable between a horizontal and a vertical position.

It is common practice to transport containers for milk to different locations in a warehouse or shop store using collapsible metal cages which are mounted on castors. These are commonly known as "roll cages".

These roll cages have a base which pivots from a horizontal to a vertical position and sides which are pivotable along a vertical axis to permit a number of cages to be stacked inside each other when empty for storage. Each shelf comprises two half shelves, the half sections being mounted on opposite respective sides of the cage and each half shelf being pivotable between a horizontal position, in which milk cartons may be stacked on and supported by the shelf, and a vertical position adjacent the side walls of the roll cage, which permits another roll cage to be stacked inside the first roll cage when the base is also pivoted into the vertical position and the sides are pivoted outwards to permit the other roll cage to be pushed inside the first roll cage.

It is desirable to have the half shelves mounted on the sides of the roll cage such that the shelves are biassed to either the horizontal load supporting position, or the vertical storage position.

Conventionally, this is achieved by manufacturing the edge of the shelf mounted along the side wall of the cage from square tube which has a straight hinge pin inserted through it and the tubes of the side walls of the cage so that the shelf pivots about the central longitudinal axis of the hinge pin. Spring loaded plungers are welded to the side tubes of the side walls of the roll cage such that the spring biassing the plunger biasses the plunger to its uppermost position when the plunger is in contact with a straight side of the square tube. Hence, when the shelf is between the vertical and horizontal position the plunger is depressed against the action of the spring by a corner of the square side wall tubing. In this manner, movement of the shelf either from the horizontal or vertical position is resisted by the biassing action of the plunger against a corner of the square sided steel tube.

However, this conventional mechanism has the disadvantage that it requires a number of components.

In particular, in addition to the square sided tube and the straight hinge pin, it requires two tubes and two plungers and two springs mounted within the tubes for each half shelf. Also, it requires the tubes to be welded on to the side tubes which makes this conventional mechanism labour intensive in assembly.

In addition, when the half shelves are assembled into the roll cage it is necessary to push each half shelf into the frame and hold it in position against the action of the springs of the plungers and, while doing this, insert the hinge pin through the side tubes of the side walls and through the middle of the square sided steel tube of the half shelve. It is particularly difficult as the springs used in the plungers are stiff in order to minimise movement of the shelf in either of the horizontal or vertical positions.

In accordance with the present invention, a hinge mechanism comprises a first member and a second member, the first member comprising a hollow tube having a polygonal internal cross section and a hinge member fixed with respect to the second member and extending from the second member into the hollow tube, the hinge member contacting opposite internal corners of the hollow tube, and the hinge member being elastically deformable such that relative rotation of the first member and the hinge member causes sides of the polygon to deform the hinge member until the hinge member elastically reforms in adjacent corners of the hollow tube.

Preferably, the hinge member comprises an elongate member which has a number of opposing bends, and the bends provide the elastic deformability to the hinge member.

Preferably, the opposing bends are in the form of curves in the elongate member.

In another example of the invention, the hinge member may comprise an elongate member having a number of cams rotationally fixed thereon and the elongate shaft is elastically deformed by the cams when the first member is rotated relative to the hinge member.

Preferably, the hinge member may take the form of a metal rod and is preferably, sprung steel rod.

Preferably, the internal cross section of the hollow tube is a regular polygon and is typically, square.

Preferably, the hinge member extends the length of the first member.

Typically, a third member may be provided at the other end of the first member, or alternatively, the second member may extend around the first member to the other end of the first member. Where a third member is provided or the second member extends around the first member to the other end of the first member, then preferably, the hinge member passes from the second member through the first member and locates in the third member or the second member at the other end of the first member.

Typically, the end of the hinge member is U shaped to locate the end of the hinge member in the second member to maintain the hinge member fixed with respect to the second member.

Preferably, the hinge mechanism is a hinge mechanism for a shelf. Typically, the shelf is attached to the first member and the second member forms part of a supporting structure for the shelf. Preferably, the shelf may form the shelf of a metal cage, which is collapsible. Typically, the metal cage may be mounted on castors and be of the type known as a roll cage.

Examples of a hinge mechanism in accordance with the invention will now be described with reference to the accompanying drawings, in which: Fig. 1 is a cross-sectional view through a first example of a hinge mechanism; Fig.2 is a side view of a hinge pin for the hinge mechanism shown in Fig.1; Fig. 3 is a partial cross-sectional view showing a roll cage incorporating the hinge mechanism of Fig. 1 and with the shelves in a vertical position; Fig. 4 is a side view of the roll cage shown in Fig. 3 with the shelves in a horizontal position; Fig. 5 is a cross-sectional view through a second example of the hinge mechanism; Fig. 6 is a cross-sectional view through a third example of a hinge mechanism; and, Fig. 7 is a cross-sectional view through a fourth example of a hinge mechanism.

Fig. 1 shows a hinge mechanism which comprises a hinge pin 1 which is located inside the first member in the form of a hollow tube of square cross section 2 and is supported at each end by a second member 3 and a third member 4. The hinge pin 1 has a flattened portion 5 at one end which engages in a slot 6 in the second member 3. The other end 7 of the hinge pin 1 engages in a hole 8 in the third member 4. At each end of the square cross-section tube 2 is a blanking plug 9 which is inserted into the respective end of the tube 2 and abuts against the respective second and third member 3, 4. Each of the blanking plugs 9 has a central through bore through which the hinge pin 1 extends.

The hinge pin 1 has a central section 10 which is offset from the end sections 11, 12, as shown in Fig.

2. Hence, when the hinge pin 1 is inserted through the second member 3 and the tube 2 to engage with hole 8 in the third member 4, the hinge pin 1 takes on the shape shown in Fig. 1 and the central section 10 locates in a corner of the tube 2 which is diagonally opposite the corner of the tube 2 in which the end sections 11, 12 locate. This is facilitated by the elastic flexibility of the hinge pin 1 which is preferably manufactured from sprung steel rod. The pin 1 can have a single bend, and can, for example, extend parallel to the tube 2 for substantially the whole of its length with a single deviation from a straight line to engage in an opposite corner of the tube 2. The bend need not be at the middle of the pin 1. Likewise the end of the pin can comprise any suitable formation to lock the pin 1 rotationally against the third member.

Fig. 3 shows a roll cage side wall 13 for a roll cage (not shown). The roll cage side wall 13 uses the hinge mechanism shown in Fig. 1. In this example, two hinge mechanisms are shown. The second member 3 and the third member 4 each form part of the side wall 13 and the tube 2 is connected to a half shelf 14 which in Fig. 3 is shown in a vertical position. The roll cage side wall 13 also includes an upper cross member 15 which connects the second and third members 3, 4 and a lower cross member 16. Located at the bottom of the second and third members 3, 4 are castors 17 which permit the roll cage, into which the roll cage side wall 13 is incorporated, to be rolled across a surface such as a floor.

Fig. 4 shows a side view of the roll cage side wall 13 showing the half shelves 14 when they are in the horizontal position. When the half shelves 14 are rotated about hinge pin 1 from the vertical position shown in Fig. 3 to the horizontal position shown in Fig. 4, the hinge pin 1 is retained rotationally stationary with respect to the members 3, 4 by virtue of the flattened portion 5 engaging in the slot 6 and the bends in the hinge pin 1 are flattened by the flat internal sides of the tube 2 pressing against the bends as the shelf 14 is rotated from the vertical position.

When the shelf 14 is at 450 from the vertical, the hinge pin 1 will have the bends compressed to the maximum and as the shelf 14 is rotated more than 450 from the vertical the bends in the hinge pin 1 will expand exerting a biassing force on the tube 2 to move the tube and the shelf 14 to the horizontal position.

This is the position in which the bends of the hinge pin 1 can expand to the maximum possible because the distance between the diagonally opposite corners of a square section tube are greater than the side wall length of the tube. This permits the shelf 14 to be sprung "locked" in either the vertical or the horizontal position and mitigates the possibility of the shelf locating in an intermediate position between the vertical and the horizontal.

Fig. 5 shows a second example of a hinge mechanism in which the hinge pin 1 is replaced with a hinge pin 18 which is straight and which has a cam 19 rotationally locked to the external surface of the hinge pin 18.

This cam 19 replaces the central offset section 10.

In addition, the hinge pin 18 has an end portion 20 which is U shaped so that the main portion of the hinge pin 18 passes through holes 21, 22 in the second member 3 and a terminal end 23 of the hinge pin 18 engages in a third hole 24 in the second member 3 to rotationally lock the hinge pin 18 with respect to the second member 3. The hinge pin 18, as with the hinge pin 1, is manufactured from sprung steel rod and in the position shown in Fig. 5 the cam 19 is located in a corner of the tube 2. If a shelf 14 is connected to the tube 2, then as the shelf 14 is rotated from the vertical to the horizontal position the cam 19 will be pressed inwardly by the flat internal side of the tube 2 and displace the hinge pin 18 from central axis 25 against the elastic biassing action of the hinge pin 18.

Hence, when the shelf moves beyond 450 from the vertical the hinge pin 18 acting through the cam will exert a force which will act to move the shelf 14 from the 450 from the vertical position to the horizontal.

Similarly, the combination of the cam 19 and the hinge pin 18 will act on the tube 2 to bias the shelf 14 to the vertical position when the shelf 14 is less than 450 from the vertical.

Fig. 6 shows a third example of hinge mechanism which incorporates a hinge pin 30 which has a U shaped end section 31 which operates in a similar manner to the U shaped end section 20 of the hinge pin 18 shown in Fig.

5. Apart from the hinge pin 30, the hinge mechanism operates in a similar manner to the hinge mechanism shown in Figs. 1 to 5, except that the hinge pin 30 is provided with three bend sections 32, 33, 34. In the hinge pin 30, the bend sections 32, 33, 34 are smooth large radius curves which blend into each other rather than discreet bends, as shown in the hinge pin 1. This has the advantage of increasing the stiffness of the hinge pin 30 and the smooth large radius bends also facilitate easier insertion of the hinge pin 30 through the second member 3, blanking plugs 9, tube 2 and third member 4. This is because the angles and the angle changes in the hinge pin 30 are not so abrupt as the angles and angle changes in the hinge pin 1.

Fig. 7 shows a fourth example of a hinge mechanism which incorporates a hinge pin 35. The hinge mechanism shown in Fig. 7 is virtually identical to the hinge mechanism shown in Fig. 6 and the hinge pin 35 is similar to the hinge pin 30 and has a U shaped end section 36 which operates in the same manner to the U shaped end sections 20, 31. The difference between the hinge pin 35 and the hinge pin 30 shown in Fig. 6 is that the hinge pin 35 incorporates six bend sections 37, 38, 39, 40, 41, 42. The greater number of bend sections 37-42 give a hinge pin 35 which is stiffer than the hinge pin 30.

Advantages of the invention is that it minimises the hinge mechanism biassing components compared with the conventional tube and sprung plunger arrangement for the shelves 14 of a roll cage. The invention enables this by incorporating a spring biassing mechanism into the hinge pin.

Modifications and improvements may be incorporated without departing from the scope of the invention.

Claims (12)

Claims:

1 A hinge mechanism comprising a first member and a second member, the first member comprising a hollow tube having a polygonal internal cross section and a hinge member fixed with respect to the second member and extending from the second member into the hollow tube, the hinge member contacting opposite internal corners of the hollow tube, and the hinge member being elastically deformable such that relative rotation of the first member and the hinge member causes sides of the polygon to deform the hinge member until the hinge member elastically reforms in adjacent corners of the hollow tube.

2 A hinge mechanism as claimed in claim 1, wherein the hinge member comprises an elongate member which has at least one bend.

3 A hinge mechanism as claimed in claim 1 or claim 2, wherein hinge member comprises an elongate member which has two or more bends.

4 A hinge mechanism as claimed in claim 2 or claim 3, wherein the bends provide the elastic deformability to deform the hinge member.

5 A hinge mechanism as claimed in any one of claims 2-4, wherein the bends are in the form of curves in the elongate member.

6 A hinge mechanism as claimed in claim 1, wherein the hinge member comprises an elongate member having one or more cam(s) rotationally fixed thereon and the elongate member is elastically deformed by the cam(s) when the first member is rotated relative to the hinge member.

7 A hinge mechanism as claimed in claim 6, having 2 or more cams.

8 A hinge mechanism as claimed in any preceding claim, wherein the hinge member is a metal rod.

9 A hinge mechanism as claimed in any preceding claim, wherein the hinge member is a sprung steel rod.

10 A hinge mechanism as claimed in any preceding claim, wherein the internal cross section of the hollow tube is a regular polygon.

11 A hinge mechanism as claimed in any preceding claim, wherein the hinge member extends the length of the first member.

12 A hinge mechanism as claimed in any preceding claim, wherein the hinge member is rotationally locked to the first member.