This invention relates to a sliding door system. There have been many prior proposals for sliding door systems, and it has been a constant endeavour in the prior art to provide a sliding door system which is simple, reliable, which has a neat, clean appearance, and which is effective to exclude drafts. All prior systems known to the present Applicant fall short, to a greater or lesser extent, of the ideal in one or more of these respects. In addition, some prior known systems present a security problem in that they cannot be securely locked in a closed position, or if so locked, present crevices or weak points which make a burglar's task of entering easier.

Many sliding door systems have been proposed in which a series of slidable doors can be moved from a so-called "closed" position to a "stacked away" position. Such door systems are sometimes called "concertina" type systems. The doors are moved one after another in sequence or may be hingedly connected together. The track arrangement may be such that the doors or panels are stacked with their planes transverse to the length of the track. Examples of this kind of system are to be seen in French Patent No. 506 626 (Wolf), Australian Application 1707/66 (Gogerty), and French Patent No. 1318077 and its counterpart U.S. Patent 3 235 915 (Glaser). A serious disadvantage of all these systems is that one door cannot be slid past an adjacent door. That is to say, if a given space is closed by a pair of track-mounted doors one of which is called door A and the other door B, then one cannot slide door A in front of (or behind) door B and enter through the gap which was formerly closed by door A, nor can one slide door B in front of (or behind) door A and enter by the space which was formerly occupied by door B.

There have been other proposals for sliding doors. For example in British Patent No. 466 466, Poschung suggested a flush-closing double door, one half of the door being so guided in its own plane as to be displaceable over the entire width of the door aperture, while the other half is suspended by means of levers displaceably guided along guides which lie parallel to those of the other door half. With this arrangement, the door half suspended by means of the levers may be swung out of closed position in which it is flush with the other door half to permit the two door halves to be displaced one with respect to the other along parallel paths. Such an arrangement is ingenious but is ill-adapted to modern conditions since the arrangement requires many custom-made parts and installation of the Poschung system would require craftsmen skilled in the fitting of mechanisms as well as in the joinery and decorative trades. In British Patent Specification No. 1 271 987, Bara Industries disclose an even more complicated arrangement for achieving flush-closing sliding doors. This relies upon having one door spring-hinged outwardly and there being a sloping or wedge-shaped edge configuration at one vertical edge of one door which helps to guide the other door into its closed position.

It is an aim of the present invention to provide a sliding door system which is improved in one or more of the above respects.

According to the present invention, there is provided a sliding door system comprising a pair of doors which are guided in their sliding movement by tracks, characterised in that a first door is guided by first and second runners, in that the first runner runs in a first track and the second runner runs in a second track, and in that the tracks are parallel or co-linear over a part of their length and divide and diverge in the region of final positioning of the door concerned whereby the first runner following the first track and the second runner following the second track cause the door in its travel to its closed position to move into a position in which it abuts and is substantially co-planar with a second door.

According to another aspect of the present invention, there is provided a sliding door system in which one door is slidable relative to another door, and the abutting edges of the two doors are substantially planar in shape (as opposed to stepped or grooved) with the angle of the plane being less than 90° and preferably between about 55 and 80° to the plane of the doors when they are in their abutting closed condition.

This construction gives the doors a neat, clean appearance when seen from the front when closed, and permits a sliding door movement to be adopted which of itself has considerable advantages.

The tracks may be disposed in the region of the top edge, or the bottom edge, or both, of the sliding doors. They may be at floor or roof level or both.

This arrangement of tracks, in conjunction with the angled surface of the edge of a pair of doors, as particularly disclosed herein, leads to a construction of sliding door system in which one door can be slid from behind the other with little effort or difficulty and can be brought into a closed or abutting position in which the doors are flush, i.e. co-planar, in which there is only one thin vertical crack visible, in which the draught exclusion characteristics are improved compared to prior art sliding doors, and in which the angled configuration of the abutting edges allows for the provision of a high level of security of fastening.

In one preferred embodiment of the present invention, there is one track on top of the other, the tracks being located substantially at the top of the doors, and the moving door has two spaced vertical suspension members, each pivotable about a respective vertical axis relative to the door. Each suspension member may be carried by a conventional slider trolley or bogie. The first track and the second track run collinear for part of their length but divide so that one edge (in particular, the edge which is leading in the closing movement) of the door is constrained to follow a

different path from the other edge (that which is trailing in the closing movement). This useful feature enables one to arrange that one door is brought by the guidance effect of the two tracks into a flush position as described above.

The invention will be better understood from the following description of illustrative embodiments thereof, these embodiments being given by way of illustration and not of limitation, and the following description being given with reference to the drawings in which:-

Figure 1 is a front view of a panel or door showing the two tracks and one possible manner of suspension;

Figure 2 is a transverse cross-sectional view on the line II— II of Figure l;

Figure 3 is a diagrammatic plan view of an end portion of the two tracks illustrating divergence and showing the guidance effect of the tracks enabling a series of sliding door panels to be transferred from an operating (closed) configuration to a transversely stacked away (open) configuration;

Figure 4 illustrates a different embodiment of the invention in which a pair of tracks are provided for use with a pair of doors such as patio doors to permit the doors to be located in an open position wherein one door is parallel to and behind the other and a closed position wherein the doors are substantially co-planar and abutted edge to edge;

Figure 5 is a cross-section taken in a vertical plane at right angles to the length of the tracks on the line V-V in Figure 4;

Figure 6 is a diagrammatic top plan view of a pair of doors in accordance with one example of the invention, in their relative positions having edges butted together, that is. the closed condition;

Figure 7 is a view similar to Figure 6 but showing the doors in their open condition; and

Figure 8 is a view similar to Figures 6 and 7 showing the doors in the position they occupy just before the right hand door makes it final movement into its closed position. The doors of Figures 6-8 are guided in their movement by a track arrangement of the kind shown in Figures 4 and 5.

Figures 9A to 9D illustrate another embodiment of the invention, Figure 9A showing a leading support fitting or bracket on a rear door when closing, Figure 9B showing a trailing support fitting on a rear door when closing, Figure 9C showing a top plan of the fitting shown in Figure 9B, Figure 9D shows a fitting for use as both a leading and a trailing fitting for a front (a leading door), the latter running on a straight continuous track analogous to track 52 of Figure 4; and

Figure 10 is a diagrammatic representation of fittings usable in the same manner as the fittings shown in Figures 9A and 9B, but related to a two-level track.

One example of the invention is illustrated in Figures 1-3. Figure 1 shows a panel or door 10, and conventional bogies or trolleys 12 and 14, there being vertical suspending rods 16 connecting each bogie 12, 14 to the panel or door 10. The suspension rods 16 are free to pivot in bearings 18 fixed in the top edge of the panel. This is to allow the bogies to articulate, i.e. pivot relative to the panel, as they follow the curved end portions of the tracks. For brevity in this particular portion of the description reference will be made only to a panel but it will be appreciated that the panel might alternatively be a door.

Figure 2 is a cross-section showing the single extrusion or profile 20 which defines an upper track along which the bogie 12 runs, and a lower track along which the bogie 14 runs. For clarity, the rods 16 are shown side by side as shown in Figure 2 but in fact they would preferably be arranged one behind the other. Figure 3 shows in plan view the top track illustrating its divergent configuration at a branching region

of the track. This arrangement is appropriate when the panels 10 are required to be moved to a transverse orientation, that is when stacking away a partition consisting of a plurality of these sliding panels. The branching region is usually at or near the end of the track. As can be seen from Figures 2 and 3, the upper track 22 and the lower track 24 diverge in V-shaped fashion, so that as the panels are pushed to the end they are gradually swung from an orientation in line with the main part of the track to an orientation transverse to it. Intermediate positions of the panels are shown at 10a and 10b.

A preferred embodiment of the invention includes two doors, one guided by one track and the other guided by a track parallel to but slightly from the first track. The tracks may be at floor or roof level.

Figure 4 is a plan view of a floor level track arrangement. As shown, the tracks are provided as grooves or slots in a block of material such as wood, concrete, or metal, but it will be appreciated that other means of providing tracks could be used such as bent sheet metal or a channel- section member or L-shaped angle members appropriately positioned and fixed to constitute the track walls. Tracks 50, 52 and 60 are shown as grooves recessed into a block 54. These are predominantly linear tracks of differing width and depth. The track 50 is relatively wide and shallow, whereas the track 52 and 60 are relatively narrow and deep. A first (normally stationary) door or panel (not shown) is guided by the track 52, and a second door or panel, which is the movable door or panel, is guided by the track 50. Tracks 50 and 60 are collinear along that part of their respective lengths which they have in common. The first door or panel is provided with a pair of rollers or ball bearings mounted for free rotation at or near the leading and trailing ends of its bottom edge. In this context in the present specification, the words "leading" and "trailing" relate to motion when the "movable" panel or door is being moved from the open to the closed position.

The first or normally stationary door has two balls or rollers of small diameter suitable for sliding or rolling movement within the track 52. The second or normally sliding door has one ball or roller at its leading end of relatively small diameter suitable for running in the narrow track 60 and the trailing end of the second door has a ball or roller of relatively large diameter suitable for running in the wide track 50. As seen at the right hand part of Figure 4, the track 50 diverts to intersect the track 52 and the track 60 has a forwardly angled portion 62 which terminates at a region which is located on a linear extension of the track 52. It will be seen from the above description that the first door can slide to and fro along the track 52 and while it does so it is constrained to follow a linear movement. On the other hand, the second door or panel slides in a linear fashion until its leading "small diameter" ball ^■ roller reaches the part 64 of the track 60 at which point the front end of the rear door is constrained to move forwardly. Shortly thereafter, the rear (larger diameter) ball or roller attached to the second door reaches the curved portion 53 of the track 50 and the rear end of the door is thereby brought forward. At the end of the closing movement of the second door the front and rear ends thereof are located on the line of the track 52 and the second door is thus disposed neatly flush with the first door. This flush disposition and the path of movement is facilitated by the arrangement of the angled surface 70 of the leading edge of the first door A and the trailing edge 72 of the second door B, as best seen in Figures 6-8. In Figures 6-8 the vertical centre lines through the roller rotational axes or through the centres of the rolling balls of the door A are indicated at 66 and those of the door B at 68.

It will be realised from a consideration of Figures 4, 6 and 7 that in moving from its "closed" position to its "open" position the door B moves behind the door A to a position wherein it is substantially parallel to the door A. Moreover, if desired, when the door B is in its closed position, the

door A can be moved (to the right from the position seen in Figure 7) to close off the gap formerly occupied by the door A. To the best of Applicants' knowledge and belief, no prior practical and inexpensive system has enabled this to be achieved.

It will be apparent that a track of configuration similar to that shown in Figures 4 and 5 may be disposed at ceiling or roof level, or in the region of ceiling and roof level, if desired, or that alternatively the doors or panels may be "top-hung" that is to say may be provided with an upper track arrangement from which the doors are suspended in the manner indicated in Figures 1 and 2.

Figures 9 and 10 show two further possible arrangements for a "top- hung" door system in which door path guidance by a dual track in the manner described above is combined with door suspension on a single wheel system instead of a "conventional" 4-wheel bogie.

Referring now to Figures 9A-9D, a track 88 is shown having a wider portion 90 in which runs rollers 91, and a narrower portion 92 in which runs rollers 93. A leading fitting 94 attached a rear door or panel 96 has a pivotable support shaft 98 carrying the freely rotatable rollers 93. The door or panel 96 is supported by a wheel 100 which runs on a flange 102 of the track. The front door 104, Figure 9D, is supported by a wheel 106 which runs on a flange 108 of a straight continuous track 110. There is one such fitting and wheel 106 at the leading end of the door and one at the trailing end. Rear door 96 is guided by track 88 whereas front door 104 is guided by track 110. Figure 9B shows that a wheel 112 which supports the trailing end of the rear door 96 runs on a flange 114 of the track 88. The rollers 93 are arranged one behind the other with reference to the track, as seen in Figure 9C, and are supported by upstanding shafts 116, Figure 9B, which are mounted on a plate 118. The latter has a bracket arm 120 which carries the wheel 112. In Figure 9C, the track 88 is omitted for clarity. The pivot axis of support shaft 124 (Figure 9B) is indicated at 126 in Figure 9C.

Referring now to Figure 10, the track is shown at 140 and has an upper track surface 142 upon which runs a wheel 144 carried by a fitting 145 attached to a leading end of a panel or door 146, and a lower track surface 148 upon which runs a wheel 150 carried by a fitting 149 attached to a trailing end of the panel or door 146. The leading fitting has a freely rotatable roller 152 which runs in a narrower channel of the track, and the trailing fitting has a freely rotatable roller 154 which runs in a wider channel of the track as illustrated. The operation and remaining structure will be understood from the foregoing description.

In a preferred version of the invention, the track arrangement according to the invention may be built up from straight sections of track which are extruded, and cast sections of track which contain the curved portions and provide the guidance to bring one door or panel into flush arrangement with the other door or panel.

The particular embodiments of the invention disclosed and illustrated herein are merely examples of the invention and other embodiments employing the invention will occur to a man of average skill in the art.