GB2236135A - Cat doors - Google Patents

Abstract

A cat door is made by injection moulding a frame 10 so as to have a compartment 12 below an opening 11 divided therefrom by a resilient sill 13. In the opening 11 a flap 20 hangs vertically from pivot means whereby it can swing about a horizontal axis 21 near its upper edge. Freedom of the flap 20 to swing in either direction can be restricted by rotation of a locking unit 26, which has disc portions 28 and 29 projecting through a slot 16 in the sill 13 so as to be capable of entrapping the lower edge 31 of the flap between them. The locking unit is assembled with the frame by deforming the sill 13. Segments of the peripheries 20 of the disc portions 28 and 29 have been removed to permit rotation of the locking unit to positions in which the flap 20 is free to swing in one or in both directions. The locking unit also comprises a projection 30 with straight sides corresponding with different peripheral regions of the disc portions. When rotated to bring successive straight sides of the projection 30 into parallelism with the underside of sill 13 the latter is stressed, providing a detent mechanism for location of the peripheries of the disc portions in different locking or unlocking relation to the flap 20. <IMAGE>

Description

"IMPROVEMENTS IN CAT DOORS" This invention relates to improvements in cat doors. By a "cat door" is meant means providing an opening in a wall or a larger door through which a small animal such as a cat can pass at will into or out of an enclosure, the opening being normally obturated by a flap hanging from a horizontal pivotal axis near to its upper edge so that the small animal can push it open.

Over the years the design of such cat doors, or "cat flaps" as they are commonly called, has become progressively more sophisticated in response to consumer demand for additional features. In an early design the flap was larger than the opening and could be pushed open only from one direction (typically from inside the enclosure). It is more common nowadays to provide a flap of the same shape as the opening but of smaller dimensions so that it can swing both ways, but this has given rise to the need for draughtproofing to prevent draughts between the periphery of the flap and the edge of the opening and magnetic attraction between the flap and opening to prevent the flap being blown open by a wind.

Cat owners also wish to prevent the admission into their homes of cats other than their own, to be able to lock the flap in the closed position e.g. when they and their cats are absent and preferably to be able selectively to prevent the flap swinging one way or the other so that their cat can exit the opening, but not re-enter or alternatively can enter but not exit again. To meet the first requirement it has been proposed that movement of the flap in the direction giving access to the enclosure is controlled by a catch released by a solenoid when a magnetic or magnetiseable "key" carried on a cat's collar comes into proximity to a reed switch located below the opening. In this way only a cat having such a "key" can enter. One form of selective lock which has been proposed comprises a rotary locking unit having parallel discs between which the lower edge of the flap can be trapped.The peripheries of the discs are cut away in such manner that by rotating the locking unit to different angular positions either the flap swings clear of the discs in both directions or in only one direction.

The provision of auxiliary features such as a catch member and associated electronics and/or a rotary locking unit requires that the frame defining the opening includes a compartment below the sill of the opening in which these devices can be located out of the way of an animal passing through the opening and protected from weather and dirt.

Because the peripheries of the discs of the locking unit, or at least one of them, must project above the level of the sill to engage the lower edge of the flap it has not been thought possible to produce the frame of such a cat door as a single, injection-moulded item. It has been thought essential to make the frame in two parts subsequently meeting in the plane of the opening so as to accommodate between them an item such as a rotary locking unit which will project into the opening, since it is well knows that no article to be injection-moulded may have an undercut, recess or rebate diminishing its area outwardly of the mould.The necessity to make the frame by assembling together in the plane of the opening two components individually injection-moulded, first positioning a rotary locking unit between them, gives rise to manufacturing and assembly problems which necessarily increase the price of the finished product.

Other factors which have increased the complexity and therefore the manufacturing costs in the case of previous proposals have involved adaptation of the spindle of the locking unit both to snap engage with and to provide a detent mechanism with special formations provided for the purpose one one part of the two-part frame.

An object of the present invention is to overcome these problems and to provide a simpler assembly, more easily and econortlically manufactured without sacrificing any of the desired features.

In accordance with one aspect of the present invention a cat door comprises a frame defining an opening in which a flap may hang vertically from a pivotal axis near to the upper edge of the flap and a compartment below the opening, the opening and compartment being divided by a sill of a material and thickness such that the sill has limited deformability, and a locking unit comprising a spindle and at least one disc portion transverse to the spindle, the compartment comprising a bearing in which the spindle can be inserted so that the locking unit is rotatable about the spindle axis with at least part of the periphery of the disc portion projecting into the opening sufficiently to obstruct swinging movement of the flap and a slot in the sill through which said periphery of the disc portion projects from the compartment into the opening when the spindle is in the bearing.

By the arrangement of the preceding paragraph the frame can be injection-moulded in one piece since it has no undercut to accommodate the periphery of the disc portion of the locking unit. After the frame and locking unit are separately moulded, preferably from a thermoplastics material, the sill is bowed upwardly into the opening to allow insertion of the spindle of the locking unit in the bearing until the disc portion(s) of the locking unit is (are) aligned with the slot. The sill can then be allowed to resume its former shape under its inherent resilience, whereupon the locking unit is trapped in position by projection of the periphery of the or each disc portion through the slot.

In accordance with a preferred but not essential feature of the present invention the resilience of the sill can additionally be utilised to provide a detent mechanism for the locking unit. A disc portion of the locking unit has on one face a central projection which, in use, will lie below one edge of the sill. The projection is shaped and dimensioned so that a series of angularly-separated "flats" at its periphery are brought in turn into parallelism with the underside of the sill as the locking unit is rotated. Between these "flats" the projection has a radially greater extent and so bows the sill upward. By springing back to its normal, flat shape as one of the flats becomes parallel with it the sill cooperates with the locking unit to provide a detent mechanism having a number of selectable "still" or stable angular positions corresponding to the number of flats.These angular positions correspond to different, optionally selectable locking conditions determined by the shape of the or each disc portion periphery.

A preferred embodiment of the present invention will now be described by way of example with reference to the accompanying diagrammatic drawings, in which: Figure 1 is a side sectional elevation of a cat door in accordance with the present invention, and Figures 2 and 3 are respectively a perspective view from in front and a rear view of the locking unit of the door of Figure 1, shown on an enlarged scale.

The cat door illustrated comprises a frame 10 injection-moulded from a suitable thermoplastics material so as to define an approximately rectangular opening 11 and a compartment 12 below the opening and divided therefrom by a sill 13. The sill 13 is in the form of a web of the moulded material which spans the frame 10 between the sides thereof, one of which is indicated at 14, and it is to be noted that with the configuration of frame illustrated, in which the compartment 12 projects forwardly, the sill 13 is of substantial length perpendicular to the plane of the opening 11. This enhances the flexibility of the free, rear end edge portion 15 of the sill in which an enclosed slot 16 is provided for a purpose to be described.

As is known per se the frame 10 has an integral peripheral flange 17 adapted to abut the exterior of a door or wall (not shown) in which an aperture has been formed to receive the frame 10. Subsequently a separately made annular trim flange 18 is brought to surround the frame 10 in abutment with the inner side of the door or wall. To complete the assembly the open, rear end of the compartment 12 of the frame is closed by a separately made facing piece 19, which may be a push-fit in the mouth of the compartment 12. In the opening 11 a flap 20 hangs vertically from pivot means (not shown) whereby the flap can swing freely in either direction about a horizontal axis 21 near to its upper edge.

The two side edges (not shown) of the flap 20 and its bottom edge 22 are preferably provided with a continuous draught-excluder strip 23 which, in the closed position of the flap 20 as shown, will cooperate with the side and bottom edges of the opening 11 to prevent draughts passing between these edges. If desired, and as is also known, one of the flap and the sill 13 may be provided with a permanent magnet and the other with a metal strip so that the magnet will tend to hold the flap in the closed position against wind forces, but not strongly enough to prevent a small animal such as a cat pushing the flap 20 from the closed position shown in either direction.

Within the compartment 12 the frame 10 has a tubular formation 24 opening rearwardly of the frame. In use this provides a bearing for the spindle portion 25 of a rotary locking unit generally indicated at 26 and shown in more detail in Figures 2 and 3. The locking unit has at its rear end a diametral rib 27 which, in use, projects from an opening in the facing piece 19 and which can be grasped between finger and thumb to rotate the locking unit 26 in the bearing 24 about the axis of the spindle 25. Between the spindle 25 and rib 27 the locking unit has parallel disc portions 28 and 29 in relation to which the spindle 25 is perpendicular and coaxial, the disc portions being spaced apart sufficiently to accommodate between them the periphery 31 of the lower edge of the flap 20 where this projects downward beyond a rebate accommodating the draught excluder strip 23.

The disc portions 28 and 29 are formed on circles of equal diameter from which segments have been removed to provide the different locking functions. Where no segment has been removed from either disc portion (the position indicated at a in Figures 2 and 3) the peripheries of the disc portions can extend above the lower edge 31 of the flap 20 so as to entrap it between. Where a segment has been removed from one disc portion 28 or 29 but not from the other (exemplified at b and c in Figures 2 and 3) the locking unit can be rotated to a position where it will obstruct swinging of the flap 20 in one direction but not in the other.

This enables the user to allow an animal out of a house but not in, or vice versa. Finally, where segments have been removed from both disc portions 28 and 29 in the same angular position (indicated at d in Figures 2 and 3) the flap 20 is free to swing in either direction. The user thus has the options "fully locked" (a), "lock out" (b), "lock in" (c) and "fully open" (d) selectable simply by suitable rotation of the locking unit.

As shown in Figure 1 the locking unit 26 is in the "fully open" position (d), which is to say that straight edges of both of the disc portions 28 and 29 are horizontal and uppermost. It will be noted, however, that even in this position the disc portions 28 and 29 both project through the slot 16 into the opening 11. To allow the locking unit 26 to be assembled with the one-piece moulding of the frame 10 the flexibility of the sill 13 is utilised. With the locking unit held with parallel straight edges of the disc portions 28 and 29 parallel with the sill 13 and uppermost the sill is deformed upwardly sufficiently to allow insertion of the spindle 25 into the bearing 24 until the disc portions 28 and 29 are aligned with the slot 16.The sill 13 is then released and by springing back to its normal, horizontal shape entraps the disc portions 28 and 29 in the slot 11 so that the locking unit 26 cannot be withdrawn again axially out of the compartment 12 unintentionally. This dispenses with the need for any additional facility for holding the locking unit 26 in place.

In the preferred embodiment illustrated the resilience of the sill 13 is additionally utilised to provide the locking unit 26 with a detent facility. As most clearly seen in Figure 2 the outward face of the leading disc portion 29 has a projection 30 with four straight sides lying on a square within the circle of the disc portion 29. Each of these straight sides is parallel with a straight peripheral portion of one of the disc portions 28 and 29; in the case of position "d" with a straight peripheral portion of both disc portions 28 and 29. The dimension of the projection 30 between parallel, straight edge portions thereof is twice the interval between the axis of the spindle 25, in the mounted position of the locking unit, and the underside of the undeformed sill 13.

The effect of this arrangement is that as the locking unit 26 is rotated so that a rounded corner of the projection 30 between two straight edges thereof at right-angles bears against the underside of the sill 13 the latter bows upward to allow the corner to pass. Once it has passed the sill 13 presses downward on the projection 30 encouraging the locking unit 26 to rotate to a position where a straight edge of the projection 30 is once again parallel with the underside of the sill so that the sill is no longer deformed. In this way the locking unit 26 "clicks" between four sequential angular positions corresponding to the optionally selectable locking conditions "a" to "d" and will tend not to remain in an intermediate position in which a rounded corner of the projection 30 is bowing the sill 13.

Claims (7)

CLAIMS:

1. A cat door comprising a frame defining an opening in which a flap may hang vertically from a pivotal axis near to the upper edge of the flap and a compartment below the opening, the opening and compartment being divided by a sill of a material and thickness such that the sill has limited deformability, and a locking unit comprising a spindle and at least one disc portion transverse to the spindle, the compartment comprising a bearing in which the spindle can be inserted so that the locking unit is rotatable about the spindle axis with at least part of the periphery of the disc portion projecting into the opening sufficiently to obstruct swinging movement of the flap and a slot in the sill through which said periphery of the disc portion projects from the compartment into the opening when the spindle is in the bearing.

2. A cat door as claimed in claim 1, wherein the locking unit comprises two generally parallel disc portions spaced apart sufficiently to entrap the flap between their peripheries and wherein the slot in the sill is dimensioned to allow peripheral portions of both said disc portions to project therethrough from the compartment into the opening when the spindle is in the bearing.

3. A cat door as claimed in claim 1 or claim 2 wherein the or each disc portion is circular with one or more segments removed such that when rotated to a position in which a straight edge is generally parallel with the sill the flap will be permitted to swing past said disc portion.

4. A cat door as claimed in any preceding claim, wherein the frame is injection-moulded in one piece from a plastics material.

5. A cat door as claimed in any one of the preceding claims, wherein the or one of the disc portions of the locking unit has on one face a central projection which, in use, will lie below one edge of the sill, the projection being shaped and dimensioned so that a series of angularlyseparated flats at its periphery will be brought in turn into parallelism with the underside of the sill as the locking unit is rotated, the projection having between the flats a radially greater extent so as to bow the sill upward as the locking unit is rotated, the arrangment being such that by springing back to its normal, flat shape as one of the flats becomes parallel with it the sill cooperates with the locking unit to provide a detent mechanism having a number of selectable stable angular positions corresponding to the number of flats.

6. A cat door as claimed in claim 52 wherein the said angular positions of the projection correspond to respective, optionally selectable locking conditions determined by the shape of the or each disc portion periphery.

7. A cat door substantially as herein described with reference to and as shown in the accompanying diagrammatic drawings.