WO2011135299A1

WO2011135299A1 - Door apparatus

Info

Publication number: WO2011135299A1
Application number: PCT/GB2011/000653
Authority: WO
Inventors: Christopher Scott Healey; Nicholas Paul Harrison
Original assignee: Christopher Scott Healey; Nicholas Paul Harrison
Priority date: 2010-04-28
Filing date: 2011-04-28
Publication date: 2011-11-03
Also published as: GB201007097D0; GB2479949B; GB2493317A; GB2479906A; GB2479949A; GB201010337D0; GB2493317B; GB201220946D0

Abstract

Apparatus for use with a sliding door, the sliding door being suitable for human and/or vehicular access, the apparatus comprising: a first system; and a second system; wherein the first system is for operating on a cable (12), the cable (12) being from a cable pulling system (6) to either the sliding door or an anchor point; the first system may be changed between a first condition and a second condition; the first condition substantially permits movement of the cable (12) by the cable pulling system (6); the second condition substantially opposes movement of the cable (12) by the cable pulling system (6); the second system is arranged to change the first system from the second condition to the first condition after a time period; and the second system comprises a mechanical timer (8) for timing the time period.

Description

DOOR APPARATUS

FIELD OF THE INVENTION

The present invention relates to apparatus for door closing devices, e.g. for use with sliding doors.

BACKGROUND

Self-closing devices for sliding door assemblies are known. For example, the doors of some cold rooms and industrial freezer have a self-closing feature. These features provide that the doors of such facilities are not left open for extended periods of time. This tends to reduce energy loss and cost, and also tend to provide a stable environment inside the facility.

It is often necessary to leave a door of such a facility open for a period of time, e.g. to move goods into and/or out of the facility. Many conventional door closing devices close the door before such a task has been completed.

Conventionally, this problem is solved by users of the facility over-riding the door closing device from the door (which may lead to door being opened for longer than is necessary), or by the use of expensive electronic timed door closing devices (such devices tend to be relatively expensive to produce, relatively expensive to install, only work with certain types of door, and/or require a power supply).

SUMMARY OF THE INVENTION

Aspects of the present invention are as defined by the appended claims. In a further aspect the present invention provides apparatus for use with a sliding door, the sliding door being suitable for human and/or vehicular access, the apparatus comprising a first system, and a second system, wherein the first system is for operating at, or proximate to, a point on a route of a cable, the route is from a cable pulling system to either the sliding door or an anchor point, the first system may be changed between a first condition and a second condition, the first condition substantially permits pulling of the cable along the route by the cable pulling system, the second condition substantially opposes the pulling of the cable along the route by the cable pulling system, and the second system is arranged to change the first system from the second condition to the first condition after a time period.

In a further aspect the present invention provides a sliding door mechanism comprising a first system, and a second system, wherein the first system acts on a door closing cable extending from either (i) a cable pulling system to a sliding door, or (ii) a fixed anchor point to a cable pulling system attached to the sliding door, the first system is arranged to provide a first condition and a second condition, the first condition substantially permits the door to be closed by the cable pulling system, the second condition substantially opposes the movement of the cable by the cable pulling system, and the second system operates to change the first system from the second condition to the first condition.

In a further aspect the present invention provides apparatus for use with a sliding door, the apparatus comprising a first system, and a second system, wherein the first system is for placing on or near a route of a cable, the route of the cable is from a cable pulling mechanism to either (i) a point on a sliding door, or (ii) a fixed anchor point with respect to which the sliding door is moveable, the first system may be changed between a first condition and a second condition, the first condition substantially permits the cable to be pulled by the cable pulling mechanism such that the sliding door is moved closer to the fixed anchor point, the second condition substantially opposes movement of cable caused by a force exerted on the cable by the cable pulling mechanism, and the second system is arranged to change the condition of the first system.

In a further aspect the present invention provides apparatus suitable for use with a sliding door, the sliding door being suitable for human and/or vehicular access, the apparatus comprising a first system, and a second system, wherein the first system is placing on a route of a cable, the route is from a system that exerts a pulling force on the cable to one of the following: (i) a sliding door, (ii) a point on a wall, the sliding door is moveable with respect to the point on the wall, the first system may be changed between a first condition and a second condition, the first condition substantially permits the system that exerts the pulling force to pull the cable and close the sliding door, the second condition substantially opposes the pulling of the cable by the system that exert the pulling force, and the second system changes the first system from the second condition to the first condition after a certain time period.

In any of the above aspects, the pulling of the cable along the route by the cable pulling system may provide automatic closing of the sliding door.

In any of the above aspects, the cable pulling system may be a winding mechanism for winding the cable.

In any of the above aspects, the winding mechanism may be arranged to automatically wind the cable.

In any of the above aspects, a maximum value of the time period may be predetermined or selected.

In any of the above aspects, there may be at least one pulley on or proximate to the route of the cable.

In any of the above aspects, the second condition may be provided by a braking mechanism that is applied to substantially prevent the pulley from allowing the cable to be moved along the route by the cable pulling system.

In any of the above aspects, the braking mechanism may comprise a brake lever.

In any of the above aspects, when the route is from a cable pulling system to the sliding door, the cable pulling system may be mounted on a wall.

In any of the above aspects, when the route is from a cable pulling system to the anchor point, the cable pulling system may be mounted on the sliding door.

In any of the above aspects, the second system may comprise a timer for timing the time period. ln any of the above aspects, the timer may begin to time the time period once the cable has been moved along its route by a certain extent in a direction opposite to the direction of travel resulting from the cable being pulled by the cable pulling system.

In any of the above aspects, the cable may be moved along its route by a certain extent in a direction opposite to the direction of travel resulting from the cable being pulled by the cable pulling system by an action of opening the sliding door.

In any of the above aspects, the timer may be a mechanical timer.

In any of the above aspects, the timer may be set by the action of the cable moving along the route in a direction opposite to the direction of travel resulting from the cable being pulled by the cable pulling system.

In any of the above aspects, the time period may be dependent on an extent of travel of the cable in a direction opposite to the direction of travel resulting from the cable being pulled by the cable pulling system.

In any of the above aspects, the cable may be moved by a first extent of travel in a direction opposite to the direction of travel resulting from the cable being pulled by the cable pulling system, and after being moved by the first extent of travel, the cable is moved by a second extent of travel in the direction opposite to the direction of travel resulting from the cable being pulled by the cable pulling system, and a time period corresponding to the first extent is different from a time period corresponding to the second extent.

In any of the above aspects, the time period corresponding to the first extent may be greater than the time period corresponding to the second extent.

In any of the above aspects, the time period corresponding to the second extent may be zero.

In any of the above aspects, the cable may be moved by an extent of travel in a direction opposite to the direction of travel resulting from the cable being pulled by the cable pulling system by an action of opening the sliding door. In any of the above aspects, the cable may comprise metal cable strands.

In any of the above aspects, the cable may be a chain.

In any of the above aspects, the sliding door may be suitable for access to one or more of the following (i) a cold room, (ii) a refrigerated room, (iii) a freezer room, (iv) a refrigerated lorry.

In any of the above aspects, the apparatus may further comprise an override system arranged to change the first system from the second condition to the first condition dependent upon an amount of tension in the cable. The override system may comprise a spring loaded lever arranged to change the first system from the second condition to the first condition when the tension in the cable falls below a given level.

In a further aspect, the present invention provides a sliding door closing device comprising apparatus according to any of the above aspects.

In a further aspect, the present invention provides a sliding door assembly comprising a sliding door for human and/or vehicular access, and a door closing device according to the above aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic illustration (not to scale) of a perspective view of a top of a door closer;

Figure 2 is a schematic illustration (not to scale) of a top-down view of the door closer 1 showing components of the door closer 1 below a plane parallel to a top surface of the door closer;

Figure 3 is a schematic illustration (not to scale) of a perspective view of the components of the door closer 1 shown in Figure 2;

Figure 4 is a schematic illustration of a perspective view of the door closer 1 showing components of the door closer 1 below a plane that is parallel to, and below, that used for Figures 2 and 3; Figure 5 is a schematic illustration of a cross section of the door closer 1 taken through a plane indicated in Figure 3;

Figure 6 is a schematic illustration (not to scale) of a perspective view of the bottom of the door closer 1 ;

Figure 7 is a schematic illustration of a cross section (through a diameter) of the first pulley 14;

Figure 8 is a further schematic illustration of a cross section (through a diameter) of the first pulley 14;

Figure 9 is a schematic illustration (not to scale) showing certain details of a system for overriding the braking mechanism when the door is closed before a timer has unwound;

Figure 10 is a schematic illustration (not to scale) showing the override system of Figure 9 in a different state; and

Figure 1 1 is a schematic illustration of a cross section of an example other embodiment of the door closer taken through a plane indicated in Figure 3.

DETAILED DESCRIPTION

In the following description, terminology such as "top", "bottom", "above", "below" etc. is adopted to describe elements of the described devices. It will be appreciated by the skilled person that such terminology is not limiting and is used merely to refer to the position of one element relative to other elements.

Figure 1 is a schematic illustration (not to scale) of a perspective view of an embodiment of a timed door closing device, hereinafter referred to as "the door closer 1 ". Figure 1 shows a view of the top of the door closer 1.

The door closer 1 comprises a chassis 2, a cover 4, a spring balance 6, and a timer 8. ln this embodiment, the chassis 2 and the cover 4 provide a housing for the components of the door closer 1 that are described in more detail later below with reference to Figure 2 to 5.

In this embodiment, the chassis 2 and the cover 4 are made of sheet steel. Also, in this embodiment the dimensions of the chassis 2 are 250mm by 120mm.

The cover 4 comprises a hole 10 through which a cable (not shown in Figure 1) runs from the spring balance 6 of the door closer 1 , out of the door closer 1 , and attaches to a sliding door (not shown), for example a door of an enclosed sliding door assembly for a drop track sliding door (e.g. a door as described in US Patent Application 2007/0227074 A1 , which is incorporated herein by reference).

In this embodiment, the spring balance 6 is mounted through the cover 4 and retained by the cover 4 and chassis 2 at one side of the door closer 1. The spring balance 6 is a conventional spring balance comprising a helically wound cable (not shown in Figure 1). One end of the cable is secured within the spring balance 6. Another end of the cable is fed through a timing mechanism (which comprises the timer 8 and is described in more detail later below), out of the door closer 1 via the hole 10, and attaches to the sliding door.

In this embodiment, the timer 8 is mounted through the cover 4 and retained by the cover 4 and chassis 2 at a side of the door closer 1 opposite the spring balance.

Figure 2 is a schematic illustration (not to scale) of a top-down view of the door closer 1 showing components of the door closer 1 below a plane parallel to a top surface of the cover 4.

For the purposes of clarity and ease of understanding, Figure 3 is a schematic illustration (not to scale) of a perspective view of the components of the door closer 1 shown in Figure 2. In other words, Figure 3 is a schematic illustration of a perspective view of the door closer 1 showing components of the door closer 1 below a plane parallel to a top surface of the cover 4. The cable of the spring balance is indicated in Figure 2 by the reference numeral 12. In Figure 2, part of the cable 12 is indicated by solid lines, and, for ease of seeing the path, or route, of the cable 12, a further part of the cable 12 is shown as a dotted line. In this embodiment, the cable 12 passes from the spring balance 6 around a portion of a first pulley 1 .

In this embodiment, the first pulley 14 is mounted on a shaft provided by a wrap spring clutch (this shaft is hereinafter referred to as the "first shaft" and is indicated by the reference numeral 16). Also, the timer 8 is coupled to the first shaft 16. The coupling of the first pulley 14 to the first shaft 16, and of the timer 8 to the first shaft 16, will be described in more detail later below with reference to Figure 5.

In this embodiment, the timer 8 (shown in Figure 1) is positioned on a top surface of the door closer 1. Also, an end of the first shaft 16 opposite the timer 8 is connected to a mechanism for setting the timer 8. This mechanism for setting the timer 8 is positioned on a bottom surface of the door closer 1 and is described in more detail later below with reference to Figures 5 and 6.

After passing around a portion of the first pulley 14, the cable passes around a portion of a second pulley 18. Thus, a path of the cable 12 describes a 'S'-shape within the door closer 1.

The second pulley 18 is mounted on a second shaft 20. In this embodiment, the second pulley 18 is coupled to the second shaft 20 such that rotation of the second pulley 18 causes rotation of the second shaft 20 and vice versa.

In this embodiment, a first end of the second shaft 20 is secured to the cover 4 at a top surface of the door closer 1 via bearing. Also, a second end, opposite the first end, of the second shaft 20 is secured to the chassis 2 at a bottom surface of the door closer 1 via a bearing. After passing around a portion of the second pulley 18, the cable 12 passes out of the door closer 1 via the hole 10 where it is attached to a sliding door.

In this embodiment, a first gear 22 is mounted on the second shaft 20 above the second pulley 18. In this embodiment, the first gear 22 is coupled to the second shaft 20 such that rotation of the first gear 22 causes rotation of the second shaft 20 and vice versa.

The first gear 22 meshes with a second gear 24. In this embodiment, the gear ratio between the first gear 22 and the second gear 24 is 1 :3. The second gear 24 is mounted on a third shaft 26. In this embodiment, the second gear 24 is coupled to the third shaft 26 such that rotation of the second gear 24 causes rotation of the third shaft 26 and vice versa.

In this embodiment, a first end of the third shaft 26 is secured to the cover 4 at a top surface of the door closer 1 via bearing. Also, a second end, opposite the first end, of the third shaft 26 is secured to the chassis 2 at a bottom surface of the door closer 1 via a bearing.

In this embodiment, a wheel, hereinafter referred to as the "brake wheel 28", is mounted on the third shaft 26 below the second gear 24. In this embodiment, the brake wheel 28 is coupled to the third shaft 26 via a sprag (one-way) bearing (not shown) as described in more detail below with reference to Figure 4.

In this embodiment, the brake wheel 28 has teeth around its edge, however, for reasons of clarity the teeth are not shown in the Figures. The functionality of the brake wheel 28 will be described in more detail later below with reference to Figure 4.

As described above, upon exiting the door closer 1 , an end of the cable 12 is attached to a sliding door.

In this embodiment, the chassis 2 of the door closer 1 is attached to a wall proximate to the sliding door. The sliding door is moveable (i.e. to open and close the door) relative to the wall. Thus, the chassis 2 of the door closer 1 is positioned at an anchor point, or a fixed point, and the sliding door is moveable relative to this anchor point. In this embodiment, the door closer 1 is attached to the sliding door via the cable 12, at the end of the cable 12 that exits the door closer 1 via the hole 10, such that the door is pulled towards the spring balance 6 if the spring balance 6 is not hindered. The door closer 1 is attached in this way such that when the sliding door is opened, the cable 12 is pulled in the direction of the arrow shown in Figure 2 and indicated by the reference numeral 29.

In this embodiment, as the cable 12 is pulled out from the door closer 1 , the second pulley 18 rotates in a clockwise direction (when viewed from above, as is the case in Figure 2).

Also, as the cable 12 is pulled out from the door closer 1 , the first pulley 14 rotates in an anti-clockwise direction (when viewed from above, as is the case in Figure 2). This anti-clockwise rotation of the first pulley 14 causes an anti-clockwise rotation of the first shaft 16, which winds the timer 8 (this functionality is described in more detail later below with reference to Figure 5). Once the timer 8 is fully wound, a slip clutch operates so that further clockwise rotation of the first shaft 16 caused by extrusion of the cable 12 does not overwind the timer 8 (as described in more detail later below with reference to Figure 5).

In this embodiment, the timer 8 is wound only by the rotation of the first shaft 16 in an anti-clockwise direction (when viewed from above), i.e. only by the opening of the door. When the door is closing (as described in more detail later below), the wrap spring clutch acts to prevent the timer 8 being back wound (or unwound) by the clockwise rotation of the first shaft 16 (as described in more detail later below with reference to Figure 5).

Thus, the cable 12 is unwound/extruded from the spring balance 6 by the opening of the sliding door.

As the sliding door is opened, the spring balance 6 attempts to wind the cable 12 into the door closer 1 , i.e. to pull the portion of the cable 12 that was unwound during a process of opening the sliding door back into the spring balance 6. In other words, as the sliding door is opened, the spring balance 6 attempts to automatically close the door. Thus, the spring balance 6 attempts to close the door as the sliding door is opened to a desired position. During a process of opening the sliding door, a force applied to the door to open it (i.e. in the direction of the arrow 29) is larger than the force applied by the spring balance 6 to rewind the cable 12.

In this embodiment, this closing of the door as soon as it is opened to a desired position is prevented by a braking mechanism of the door closer 1. The braking mechanism is described in more detail later below with reference to Figure 4.

The braking mechanism of the door closer 1 is engaged (i.e. it prevents the return of the cable 12 to the spring balance 6 and thereby prevents the closing of the sliding door by the door closer 1 ) until the timer 8, that was wound by the opening of the door as described above, unwinds.

In this embodiment, the timer 8 begins unwinding when it is no longer being wound. For example, the timer 8 may begin unwinding after it has been fully wound by the opening of the door, or the timer 8 may begin unwinding after it has been partially wound by the opening of the door by a distance that is insufficient to cause the timer 8 to be fully wound. In this embodiment, the amount of time that it takes the timer to unwind from its fully wound state may advantageously be adjusted, as described in more detail with reference to Figure 6.

After the timer 8 has fully unwound, the braking mechanism is disengaged and the spring balance 6 is free to rewind the cable 12 into the door closer 1 , i.e. to its original position, thereby closing the sliding door.

Figure 4 is a schematic illustration of a perspective view of the door closer 1 showing components of the door closer 1 below a plane that is parallel to and below that used for Figures 2 and 3. Figure 4 shows certain details of the braking mechanism of the door closer 1. The braking mechanism comprises the brake wheel 28, a cam 30, and a brake lever 32. The cam 30 is mounted upon the first shaft 16 (as described in more detail later below with reference to Figure 5). In this embodiment, the cam 30 is coupled to the first shaft 16 such that rotation of the first shaft 16 causes rotation of the cam 30.

The brake lever 32 is mounted on the second shaft 20. In this embodiment, the brake lever 32 is spring mounted such that when a lobe of the cam 30 is engaged with the brake lever 32, the brake lever 32 is held away from the brake wheel 28. Thus, rotation of the second and third shafts 20, 26 (which are coupled together via the first and second gears 22, 24 as described above with reference to Figure 2 and 3) and the second pulley 18, in both clockwise and anti-clockwise directions, is allowed. Furthermore, when a lobe of the cam 30 disengages from the brake lever 32, the brake lever 32 is forced against the brake wheel 28 thereby opposing rotation of the brake wheel 28 and also the second and third shafts 20, 26. In this embodiment, a surface of the brake lever 32 comprises teeth such that when the brake lever 32 is forced against the brake wheel 28, the teeth of the brake lever 32 mesh with the teeth of the brake wheel 28. These teeth of the brake lever 32 (and those of the brake wheel 28) are not shown in the Figures for the purposes of clarity of the drawings. The use of teeth on the brake wheel 28 and the brake lever 32 tends to greatly increase friction between the brake wheel 28 and the brake lever 32 over a use of a brake wheel and lever not comprising such teeth. This advantageously tends that the braking force applied to the brake wheel by the brake lever 32 is relatively large, compared with that in systems in which the brake wheel and brake lever do not comprise teeth.

In operation, when the sliding door is opened, the movement of the cable 2 through the door closer 1 causes anti-clockwise rotation of the first shaft 16. This anti-clockwise rotation of the first shaft 16 winds the timer 8 as described above. Also, in this embodiment this anti-clockwise rotation of the first shaft 16 rotates the cam 30 such that the lobe of the cam 30 disengages from the brake lever 32.

Thus, the brake lever 32 is forced against the brake wheel 28 thereby opposing rotation of the brake wheel 28. In this embodiment, the sprag (not shown), via which the brake wheel 28 is mounted on the third shaft 26, provides that although the rotation of the brake wheel 28 is opposed, the third shaft 26 is able to rotate (in one direction) as the cable 12 is pulled from the door closer 1. Thus, the one-way rotation of each of the second and third shafts 20, 26, the first and second gears 22, 24, and the second pulley 18, as the cable 12 is pulled out of the door closer 1 , is not opposed by the brake lever 32 being forced against the brake wheel 28. In other words, the sprag provides that clockwise rotation of the second pulley 18 (when viewed from above) is not opposed when the brake lever 32 is engaged with the brake wheel 28. Also, the sprag provides that anti-clockwise rotation of the second pulley 18 is opposed when the brake lever 32 is engaged with the brake wheel 28.

As the sliding door is opened, the timer 8 is wound and the cam 30 is rotated anti-clockwise such that the lobe of the cam 30 disengages from the brake lever 32. As the timer 8 unwinds, the timer rotates the first shaft 16, and therefore also the cam 30, in a clockwise direction (when viewed from above). The first shaft 16 is rotated by the timer 8 until the cam 30 is in its original position, i.e. a position wherein the lobe of the cam 30 engages the brake lever 32. Therefore, when the timer 8 is unwound, the cam 30 holds the brake lever 32 away from the brake wheel 28. At this stage, the brake wheel 28, and the second and third shafts 20, 26 are free to rotate, and rotation of the second pulley 18 in an anti-clockwise direction is not opposed. Thus, when the timer 8 has unwound, the spring balance 6 is able to rewind the cable 12 into the door closer 1 , thereby closing the sliding door.

Figure 5 is a schematic illustration of a cross section of the door closer 1 taken through a plane X-X, which is perpendicular to the top surface and a side surface of the door closer 1 and passes through an axis of the first shaft 16. The plane X-X is indicated in Figure 3 by a dotted line.

Figure 5 shows in further detail how the timer 8, the first pulley 14, and the first shaft 16 are coupled together in this embodiment. Figure 5 shows inter alia the following components: the timer 8 comprising a timer shaft 100 protruding from the timer 8; a wrap spring clutch comprising a shaft provided by the wrap spring clutch (i.e. the first shaft 16) and wrap spring clutch collar 101 ; a slip clutch comprising a slip clutch collar 32 and a slip clutch ring 103; a finger spring 104; a retaining ring 105; the cam 30 comprising a channel 110 through the cam 30; and the second pulley 14.

The timer shaft 100 is coupled to the first shaft 16 and the cam via a grub screw (not shown in Figure 5) that is positioned though the channel 110. Thus, rotation of the timer shaft 100 causes corresponding rotation of the cam 30. Also, rotation of the timer shaft 100 causes rotation of the first shaft 16 and vice versa.

In addition to being coupled to the timer shaft 100 as described above, the first shaft 16 is coupled to the wrap spring clutch collar 101 via a spring (not shown in Figure 5).

In addition to being coupled to the first shaft 16, in this embodiment the wrap spring clutch collar 101 is coupled to the slip clutch collar 102 via knurling on surface of the wrap spring clutch collar 101 that is in contact with a surface of the slip clutch collar 102, and corresponding knurling of that surface of the slip clutch collar 102, such that the two components 101 , 102 are substantially fixed relative to each other.

In addition to being coupled to the wrap spring clutch collar 101 , the slip clutch collar 102 is coupled to the slip clutch ring 103 such that the slip clutch ring 103 is positioned substantially around the slip clutch collar 102, and is able to slide, or slip, relative to the slip clutch collar 102 along its axis to some extent. The slip clutch collar 102 is also coupled to the retaining ring 105 which has a fixed position relative to the slip clutch collar 102. A finger spring 104 is positioned on the retaining ring 105 between the retaining ring 105 and the slip clutch ring 103. The retaining ring 105 provides a relatively fixed point for the finger spring 104 to react against during operation of the door closer 1. In this embodiment, the retaining ring 105 is retained in a substantially fixed vertical position by a circlip.

In this embodiment, a plurality of pins (not shown in Figure 5) is positioned through the slip clutch ring 103. Each pin in the plurality of pins has a first end and a second end opposite the first end. The first end of each of the pins is positioned through at least part of the retaining ring 105. This provides that rotation of the slip clutch ring 103 about its axis produces a corresponding rotation of the retaining ring 105 about its axis, and vice versa. A second end of the each of the pins engages with the second pulley as described below.

During operation, as the cable 2 is pulled from the door closer 1 (by the opening of the sliding door), the second pulley 14 is rotated. In this embodiment, the second end of each of the pins is positioned through the slip clutch ring 103 and engages into a counterbored depression in the lower surface of the second pulley 14. The pins are fixed to the slip clutch ring 103. The second end of each of the pins is ball nosed in form and engages into a corresponding ball nosed counterbored depression in the lower surface of the second pulley 14. In this way, the first pulley 14 and the slip clutch ring 103 are coupled together. Thus, the rotation of the second pulley 14 causes a corresponding rotation of the slip clutch ring 103. Since the slip clutch ring 103 is coupled to the retaining ring 105 via the pins, the rotation of the slip clutch ring 103 causes a corresponding rotation of the retaining ring 105. This rotation of the retaining ring 105 causes corresponding rotation of the slip clutch collar 102, which in turn produces a corresponding rotation of the wrap spring clutch collar 101. As the wrap spring clutch collar 101 is rotated, the spring coupling the wrap spring clutch collar 101 and the first shaft 16 is tightened, thereby locking together the wrap spring clutch collar 101 and the first shaft. Thus, a corresponding rotation of the first shaft 16 is produced. Since the first shaft 16 and the timer shaft 100 are coupled together (via the grub screw), the rotation of the first shaft 16 causes a corresponding rotation of the timer shaft 100 (and the cam 30), thereby winding the timer 8.

The timer 8 is wound in such a way until it is fully wound, or the second pulley is no longer rotated (i.e. the sliding door is opened no further). In the event that the second pulley 14 is longer rotated, the timer 8 begins to unwind, as described in more detail later below). In the event that the timer 8 becomes fully wound, the ball-nosed second ends of the pins disengage from the corresponding ball nosed counterbored depressions in pulley 14, under a pre- set load, and the slip clutch ring 103 moves downwards. In other words, the slip clutch slips, i.e. slip clutch ring 03 slips downwards towards the retaining ring 105, thereby disengaging the second end of the pins from the second pulley 14. Thus, since the second pulley and the slip clutch ring 103 are no longer coupled, further rotation of the second pulley 14 (by further opening of the sliding door) no longer drives the slip clutch ring 103, and the timer 8 is wound no further. Once timer 8 stops being wound, it begins to unwind.

As the timer 8 unwinds, the timer shaft 100 is rotated, by the timer 8, in a direction opposite to that the direction that winds the timer 8. Such rotation of the timer shaft 100 causes a corresponding rotation of the first shaft 16 (and the cam 30) because the timer shaft and the first shaft are coupled together via the grub screw.

Once the wrap spring clutch collar 101 is no longer being driven (i.e. either the slip clutch has slipped to disengage from the second pulley 14, or the second pulley 14 is no longer being rotated by the opening of the sliding door), the spring coupling the wrap spring clutch collar 101 and the first shaft 16 together opens up. Because the spring has opened up, the wrap spring clutch collar 101 and the first shaft are no longer locked together. Thus, the rotation of the first shaft 16 caused by the unwinding of the timer 8 does not produce a corresponding rotation of the wrap spring clutch collar 101. In other words, the timer 8 may unwind without producing corresponding rotation of the wrap spring clutch collar 101 , the slip clutch collar 102, the retaining ring 105, the slip clutch ring, and (if the pins are engaged with the second pulley 14), the second pulley 14.

An advantage of providing that these components are not driven when the timer 8 unwinds is that the cable 12 is not pulled into the door closer 1 by the unwinding action of the timer 8.

A further advantage of providing that these components are not driven when the timer 8 unwinds is that a timer with relatively low output torque may be used, e.g. a conventional timer. Such timers tend to be advantageously simple and low cost. Figure 6 is a schematic illustration (not to scale) of a perspective view of the bottom of the door closer 1.

In this embodiment, the door closer 1 further comprises a knob for adjusting the tension of the spring balance 6, hereinafter referred to as the "tension knob 36", and a timer adjuster 38.

The tension knob 36 may be rotated thereby increasing or decreasing the level of tension of the spring balance 6. This allows for the increasing or decreasing of the force that the spring balance 6 applies to the cable 12 when attempting to close the sliding door. Thus, it tends to be relatively easy to adapt the door closer 1 for use with doors of different weights. In other words, the door closer 1 tends to provide a relatively easy means of providing that the force with which a door (of any weight) is closed may be adjusted so that the door is not closed too slowly or too quickly, and that the door is closed with sufficient force to properly such the door.

The timer adjuster 38 comprises a plate that is rotatable about the first shaft. In this embodiment, the plate comprises a protrusion and a plurality of slots through which a screw may be inserted to lock the plate in position with respect to the chassis 2.

In this embodiment, a pin protrudes from the first shaft 16 at the end of the first shaft proximate the plate. The pin is positioned substantially perpendicular to the axis of the first shaft 16. As the timer 8 is wound by the door being opened, the first shaft 16 rotates until the pin on the first shaft comes in contact with the protrusion on the plate. At this point, the slip-clutch slips to prevent the timer 8 from being over-wound. Thus, the position of the protrusion of the plate determines the degree to which the timer 8 may be wound before the slip-clutch prevents further winding of the timer. The position of the protrusion of the plate may be selected, e.g. by a user or installer of the door closer 1, by selecting a position of the plate around the first shaft 16. The plate is secured in its selected position relative to the chassis 2 using a screw inserted through one of the plurality of slots in the plate. ln other words, how far the timer 8 may be wound (by the above described anti-clockwise rotation of the first shaft 16) before the slip-clutch operates to avoid the over-winding of the timer 8 is determined by the position of the plate. The position of the plate may be selected or adjusted, for example by an installer of the door closer 1. This advantageously provides that it is possible to set the amount of time that is allowed to elapse before the door closer 1 closes the door, i.e. "dwell time". This it tends to be possible for a user of the device to set a "maximum" time that they allow a door to be left open before it is closed by the door closer 1. In this embodiment, the timer adjuster 38 is set so that the sliding door may be left open for a time of up to 15 minutes, before the door closer begins to close the door.

In other embodiments, the timer adjuster comprises different components that provide the above disclosed functionality. Also, in other embodiments the timer may be set so that the door is left open for a different appropriate length of time before the door begins to be closed by the door closer.

Figure 7 is a schematic illustration of a cross section (through a diameter) of the first pulley 14. The second pulley 18 has a corresponding V- shaped groove that provides the same effect as that described below for the V-shaped groove 52 of the first pulley 14.

The first pulley 14 comprises a V-shaped groove 52 around its circumference. The cable 12 (also shown in Figure 7) runs around a portion of the V-shaped groove 52.

During operation, when the sliding door is opened, the cable 12 is relatively taught, i.e. there is relatively high tension in the cable 12. As a result of this high tension, the cable 12 tends to be forced towards the bottom of the V-shaped groove 52. As the cable 12 moves towards the bottom of the V- shaped groove 52, the sides of the V-shaped groove 52 in effect 'grip' the cable 12. Thus, friction between the cable 12 and the first pulley 14 is increased. This tends to provide that, when the tension in the cable 12 is high, movement of the cable 12 (by either the opening of the sliding door, or by winding of the cable 12 by the spring balance 6) causes a corresponding rotation of the first pulley 14. Moreover, when the tension in the cable 12 is high, movement of the cable 12 tends to require that the first pulley 14 is rotated correspondingly, i.e. if for example the first pulley 14 is in some way prevented from rotating whilst the tension in the cable 12 is high, then movement of the cable 12 along its route will be impossible or relatively difficult.

Also, if tension in the cable 12 becomes relatively low (for example by someone manually closing the sliding door before the timer 8 has unwound and released the braking mechanism), the cable 12 tends to move away from the bottom of the V-shaped groove 52 of the first pulley, as shown schematically in Figure 8. In this position, the cable 12 is in contact with a relatively small portion of the first pulley 14. Thus, friction between the cable 12 and the first pulley 14 is relatively low. This tends to provide that, when the tension in the cable 12 is low, the cable 12 is moveable along its route without necessarily causing a corresponding rotation of the first pulley 4 (the cable 12 may slide around the first pulley 14 as the friction between the cable 12 and pulley 14 is low). Moreover, when the tension in the cable 12 is relatively low, non-movement of the first pulley 14 does not prevent movement of the cable 12 along its route.

The above described V-shaped groove features of the pulleys 14, 16 advantageously tend to provide that when tension is reduced in the cable 12 (e.g. by manually closing the sliding door before the timer 8 has unwound), the cable 12 is permitted to be moved along its route by the recalling action of the spring balance 6 until the relatively high tension in the cable 12 is restored (and the cable 12 is positioned once more towards the bottom of the V-shaped grove of the pulleys 14, 16). This tends to alleviate problems, such as safety risks, caused by having loose cable on door assemblies.

If, for example, the sliding door is partially closed before the timer 8 unwinds, the tension in the cable 12 is reduced and the cable moves out from the bottom of the V-shaped grooves of the pulleys 14, 16 thereby reducing friction between the cable 12 and the pulleys 14, 16. This reduction in friction means that the cable is able to be moved along its route by the action of the spring balance 6 without the pulleys 14, 16 needing to be rotated. As the slack in the cable 12 is taken up by the spring balance 6, the cable 12 becomes tight again (i.e. tension in the cable 12 is restored) and the cable 12 moves towards the bottom of the V-shaped grooves of the pulleys 14, 16. Thus, friction between the cable 12 and the pulleys 14, 16 is increased and the spring balance 6 is incapable of winding more of the cable 12 back into the door closer without the rotation of the pulleys 14, 16. Since the timer 8 has not wound down, rotation of the second pulley 18 is opposed by the above described braking mechanism. Thus, further movement of the cable 12 along its route by the action of the spring balance 6 tends to be prevented (until the timer 8 unwinds and the braking mechanism is disengaged, hereby allowing free rotation of the second pulley 18).

In the above embodiment, the V-shaped grooves 52 of the pulleys 14, 18 advantageously tends to provide that when a door is closed before the timer 8 has unwound, e.g. by manually shutting the door, cable 12 that would otherwise be loose outside the door closer 1 is wound back into the door closer 1. This tends to alleviate problems, such as safety risks, caused by having loose cable on door assemblies. In other embodiments, this feature is provided by a different appropriate feature, for example a system for overriding the braking mechanism when the door is closed before the timer 8 has wound down. An example of such an overriding will now be described with reference to Figures 9 and 10.

In this embodiment, a series of pins (not shown in the Figures) are positioned proximate to the edges of the pulleys 14, 16. The pins are positioned through the door closer 1 , from the top surface of the door closer (i.e. the top of the cover 4), to the underside of the door closer 1 (i.e. the chassis 2). The pins are substantially parallel to the spindles 16, 20, 26. The pins oppose movement of the cable 12 away from the pulleys 14, 16, thereby acting to prevent the cable 12 from totally disengaging with the pulleys 14, 16 (for example, when the cable 12 becomes slack due to the closing of the sliding door before the timer 8 has unwound). In other embodiments, such pins are not present. In other embodiments, other means for opposing or prevent the cable 12 from coming off a pulley 14, 16 are used. For example, in other embodiments one or more of the pulleys comprises relatively long "walls" extending from the tops of the V- shaped grooves. Such walls restrict movement of the cable in directions parallel to the axis of the pulley, but allow significant radial movement of the cable 12 from the pulley. Figure 9 and Figure 0 are schematic illustrations (not to scale) showing certain details of a system for overriding the braking mechanism when the door is closed (e.g. manually) before the timer 8 has wound down.

The system for overriding the braking mechanism, hereinafter referred to as the "override system" comprises a spring-mounted lever, hereinafter referred to as the "tension lever 40". One end of the tension lever 40 is mounted to the chassis 2 via a pivot 42. A roller 44 is mounted to the tension lever 40 at an end of the tension lever 40 that is opposite to the pivot end.

In this embodiment, the roller 44 is a pulley that is free to rotate in both clockwise and anticlockwise directions (when viewed from above as in Figures 9 and 10) as the cable is pulled along its path (in either direction, i.e. by the action of opening the door, or by the action of the spring balance 6). In this embodiment, the override system is positioned within the door closer 1 such that the roller 44 contacts the cable 12 at a point along the route of the cable between the second pulley 18 and a point at which the cable 12 attaches to the door.

In this embodiment, the tension lever 40 is spring loaded about the pivot 42 such that a force is applied to the cable 12 via the roller 44. This force is indicated in Figures 9 and 10 by a solid arrow and the reference numeral 46.

Figure 9 schematically shows a state of the door closer 1 when the door is being opened or has been opened to some extent. In this case the cable 12 has been pulled such that it is substantially taut. The force holding the cable 12 taut, i.e. the force exerted on the door to open the door, or the weight of the door once it is opened, is sufficient to overcome the force 46 exerted on the cable 12 by the override system (i.e. by the tension lever 40 via the roller 44). Thus, in this embodiment, the tension lever 40 is held in a substantially horizontal position (when viewed from above as in Figure 9) by the cable 12.

Figure 10 schematically shows a state of the door closer 1 as the door is being closed manually, before the timer 8 has wound down and triggered the closing of the door by the spring balance 6. In this case, as the door is closed manually, the tension in the cable 12 is released, or reduced. The force holding the cable 12 taut is now insufficient to retain the tension lever 40 in its horizontal position (as shown in Figure 9). Thus, the tension lever 40 is rotated clockwise (when viewed from above as in Figure 10) by the force 46 resulting from the spring loading of the tension lever 40.

In this embodiment, the rotation of the tension lever 40 (i.e. the movement illustrated in Figures 9 and 10) by a certain amount triggers the release of the brake lever 32 from the brake wheel 28, thereby allowing the spring balance 6 to rewind the cable 12 and close the door.

In other words, as the door is closed manually (before the timer 8 has unwound), the tension is the cable 12 is reduced. This reduction in cable tension permits the tension lever 40 of the override system to move through a certain distance. This movement of the tension lever 40 triggers the braking mechanism to unlock, permitting the cable to be wound into the door closer 1.

In this embodiment, the distance through which the tension lever 40 needs to move to trigger the release of the brake lever 32 from the brake wheel 28 may be advantageously selected by a user or installer of the door closer 1.

The above described override system advantageously tends to provide that when a door is closed before the timer 8 has unwound, e.g. by manually shutting the door, cable 12 that would otherwise be loose outside the door closer 1 is wound back into the door closer 1. This tends to alleviate problems, such as safety risks, caused by having loose cable on door assemblies.

Thus, a mechanical timed door closer is provided.

An advantage provided by the above described door closer is that the device is independent of the rest of a sliding door assembly. Thus, it tends to be advantageously possible to install a sliding door and the door closing device on site in a modular fashion, with inherent design flexibility, or for example allows retro-fitting of the door closing device to an existing sliding door assembly. An advantage provided by the above described door closer is that a door is closed after a length of time set by a user. This tends to alleviates problems caused by leaving doors open for extended periods of time. For example, a problem of energy loss from and/or temperature rise in an industrial freezer if a door is left open may be alleviated.

A further advantage provided by the above described door closer is that it is possible to set a time that is allowed to elapse before the door closer begins to close the sliding door. Conventionally, a door may begin closing before a party has finished a task that requires, or it is advantageous for, the door to be open. The ability to set a delay time for the closing of the door tends to alleviate this problem.

A further advantage provided by the above described door closer is that the door closer is mechanical, i.e. no electricity is required by the door closer to provide the above described functionality. This tends to provide that the above described door closer is of lower cost (e.g. production and running cost) compared to its conventional counterparts. Also, the cost of installation of the door closer tends to be lower than it is for conventional electronic door closers because, for example because additional costs relating to complying with building and other regulations, and/or costs relating to connecting a device to a power source, tend to be avoided. Moreover, a door closer according to the above embodiments tends to work despite power-cuts, in which conventional electronic door closers tend not to. Moreover, an advantage of the device working despite a power cut tends to be particularly advantageous when the device is used on a door of a freezer or cold room, as it means that the door will not be left open for an extended period in a situation where it particularly desirable to maintain the cold temperatures of the freezer/cold room for as long as possible.

A further advantage of the above described door closer is that the timer is set/wound by the movement of the cable as the door is opened. Thus, the dimensions and/or type of door with which the door closer is used tend not to have any effect of the operation of the timer. Conventionally, a plunger/button type apparatus is used to reset an electronic timer, whereby a plunger or button is pressed when a door is closed, thereby resetting a timer. Use of such a device tends to be limited to door assemblies on which a button/plunger type device may be fit. A door closer according to the above embodiments tends not to have such limitations.

A further advantage provided by the above described door closer is that the device tends to operate irrespective of the extent to which a door is opened. For example, the device advantageously tends to work even if a door is only partially opened. This advantage is provided by the feature that the timer begins unwinding when it is no longer being wound, i.e. the timer may begin unwinding after it has been fully wound by the opening of the door, or after it has been partially wound by the opening of the door by a distance that is insufficient to cause the timer to be fully wound. This may be advantageous in situations where a door is often opened to different degrees, for example a wide door that may be opened to allow access for a vehicle, but is also partially opened to allow access for a person. Many conventional door closing devices only operate if a door is fully opened.

In the above embodiment, the door closer comprises a geared braking mechanism. However, in other embodiments the above described gearing between the second and third shafts (i.e. between the second pulley and the brake wheel) is not implemented. For example, in a different embodiment the first and second gears, and the third shaft may be omitted from the device, and the brake wheel may be mounted onto the second shaft, e.g. below the second pulley. The brake lever pushes against/is held away from the brake wheel mounted on the second shaft. In such an embodiment, a rotation of the second pulley through a certain angle, whilst the braking mechanism is engaged, means that the brake wheel tends to be rotated through the same angle. Thus, the braking mechanism of this embodiment tends not to be as effective as the geared braking mechanism. However, as a trade-off, the door closing device comprising the relatively simple, non-geared braking mechanism tends to be easier and cheaper to produce compared to the device comprising the geared braking mechanism. ln the above embodiments, the brake wheel and the brake lever each comprise teeth. These teeth mesh with those on the other component (i.e. the teeth of the brake wheel mesh with those of the brake lever and vice versa) when the brake lever is forced against the brake wheel. However, in other embodiments, the brake wheel and/or the brake lever comprise no such teeth. In such embodiments, a braking force supplied by the friction of the brake lever on the brake wheel tends to be less than that in embodiments comprising teeth. Also, in other embodiments, the brake wheel and/or the brake wheel are replaced by a different appropriate releasable braking mechanism, for example a braking clamp that may clamp the brake wheel, or a retractable rod that may be inserted through a portion of the brake wheel thereby preventing its rotation.

In the above embodiments, the gear ratio between the first gear and the second gear is 1 :3, i.e. the first gear is larger/has more teeth than the second gear. In other embodiments, a different gear ratio is used, for example a 1 :1 gear ratio. An advantage provided by the 1 :3 gear ratio is that loading on the teeth of the brake wheel and brake lever tends to be substantially reduced (by a factor of three in this embodiment) compared to embodiments in which the brake wheel is mounted on the second shaft and brake lever is applied to this brake wheel to stop it rotating. In other words, if the braking wheel were mounted on the second shaft, in order to prevent the second shaft rotating anticlockwise (when viewed from above) by a certain distance, a force of a certain magnitude would be applied by the braking lever. Thus the loading on the teeth of the brake wheel/lever would be a certain level. On the other hand, having the brake wheel on the third shaft and having the above described gearing (with the 1 :3 gear ratio between first and second gears) means in order for the second shaft to rotate anti-clockwise by the certain distance, the brake wheel would need to rotate by three times that distance. Thus, the magnitude of the force to prevent this motion is a third of that used in the embodiment in which the braking wheel is mounted on the second shaft. Thus the loading on the teeth of the brake wheel/lever is a third of the certain level. This advantageously tends to reduce the force that is used to unlock the braking mechanism, i.e. the force that the cam 30 exerts on the braking lever (caused by the rotation of the first shaft by the timer) is reduced.

A further advantage of the 1 :3 gear ratio between the first and second gears is that in order for the first gear to rotate through a certain angle, the second gear is rotated through a relatively larger angle. Thus, the braking mechanism of the above described door closer (described in more detail above with reference to Figure 4) tends to be particularly advantageous over a braking mechanism that does not implement such gearing. This is because movement of the second pulley in an anti-clockwise direction through a certain angle, whilst the breaking mechanism is engaged, tends to require that the brake wheel is rotated through a relatively large angle whilst the brake lever is forced against it. In other words, whilst the brake lever is forced against the brake wheel (i.e. the braking mechanism is engaged) a small movement of the brake wheel (e.g. if the brake wheel slips against the brake lever) translates to a much smaller, or negligible, movement of the second pulley in the anti-clockwise direction.

In the above embodiments, the door closer is used to close a sliding door, e.g. a sliding door of an industrial freezer or cold room. However, in other embodiments, the door closer may be used to close a different type of door, e.g. a shutter (e.g. a shutter on a shop front or warehouse), a sliding gate (e.g. a security gate of a commercial or private property), and so on.

Also, in other embodiments the door closer device is used in any appropriate assembly, the cable of the door closer being attached to a component of the assembly, movement of that component causes the cable to be drawn from the closer and the setting of the timer, and the spring balance provides movement of the component back to its original position when the timer has unwound.

In the above embodiments, the first pulley is coupled to the first shaft via the slip clutch and the wrap spring clutch. As the first pulley rotates, the timer is wound until it is fully wound, at which point the slip clutch acts to oppose overwinding of the timer. The wrap spring clutch acts to provide that the first shaft is freely rotatable by the timer as the timer unwinds. However, in other embodiments a different system couples the first pulley the first shaft. For example, in other embodiments a bendix drive (e.g. such as that used in a starter motor of an internal combustion engine) is used as a disengagement mechanism to enable the timer to unwind (once the first pulley stops rotating) without back-driving the system. Also, in other embodiments the first pulley is mounted on a first shaft as follows. The first pulley is coupled, e.g. by a process of riveting, to a first half of the slip-clutch. A second half of the slip clutch is coupled to the first shaft. Also, a sprag bearing, or sprag clutch, (i.e. a unidirectional bearing, or a gearing that rotates in only one direction), hereinafter referred to as the "first shaft sprag", is positioned inside the second half of the slip clutch.

Figure 11 is a schematic illustration of a cross section of this example other embodiment of the door closer taken through a plane X-X, which is perpendicular to the top surface and a side surface of the door closer and passes through an axis of the first shaft. The plane X-X is indicated in Figure 3 by a dotted line. Figure 11 shows in further detail how the timer 8, the first pulley 14, the first shaft 16, the cam 30, the brake lever 32, a first shaft sprag 33, and a further slip-clutch 34 are coupled together. In this embodiment, as the cable is pulled out from the door closer, the first pulley rotates in an anticlockwise direction. This anti-clockwise rotation of the first pulley causes an anti-clockwise rotation of the first shaft. This anti-clockwise rotation of the first shaft winds the timer. Once the timer is fully wound, the further slip clutch (shown in Figure 11) operates so that further clockwise rotation of the first shaft caused by extrusion of the cable does not over-wind the timer. The function of the first shaft sprag is such that the timer is wound only by the rotation of the first shaft in an anti-clockwise direction, i.e. only by the opening of the door. When the door is closing, the first shaft sprag disengages the first pulley from the timer, thereby preventing the timer being back wound (or unwound) by the clockwise rotation of the first shaft. In this embodiment, the timer has sufficient output torque to drive the components coupled to the first shaft. In the above embodiments, the spring balance provides a mechanism from which the cable may be pulled, and into which the cable is returned. However, in other embodiments the functionality of the spring balance, i.e. allowing release of a length of cable under a force and drawing back the length of cable upon release of the force, may be provided by a different appropriate means, for example a constant force spring, or a counter-weight that acts under gravity.

In the above embodiments, the door closer 1 comprises two pulleys, namely the first pulley and the second pulley. The use of two pulleys provide that a proportion of the cable that is in contact with a pulley at any point in time tends to be greater than a proportion of the cable that is in contact with a pulley in embodiments that comprise fewer pulleys (i.e. a single pulley). This advantageously tends to increase the level of friction on the cable at any point in time, compared with the level present in embodiments in which only a single pulley is used. This increased friction tends to advantageously oppose movement of the cable around a pulley without the pulley rotating. Thus, a problem of the spring balance pulling the cable back into the door closer (thereby closing the door), whilst the braking mechanism is engaged, tends to be alleviated. However, in other embodiments the door closer comprises a different number of pulleys, for example a single pulley. In such an embodiment a braking mechanism acts to oppose movement of the single pulley and thereby the closing of the door until a timer has unwound.

In the above embodiments, the door closer comprises a chassis and a cover which provide a housing for certain other components of the door closer. These components advantageously tend to protect the components within the housing from dirt and/or damage, thereby tending to reduce a risk of the door closer malfunctioning. However, in other embodiments the door closer does not comprises a chassis or cover, and/or no housing for the other components is provided. This advantageously tends to reduce the cost of the door closer.

In the above embodiment, the door closer 1 comprises pulleys having V- shaped grooves (as described above with reference to Figures 7 and 8), which tend to provide that cable is automatically wound back into the door closer if the door is closed before the timer has unwound. Other embodiments may comprise the he override system (as described above with reference to figures 9 and 10) instead of or in addition to the V-shaped grooves. The override system automatically triggers the release of the braking mechanism dependent upon a tension in the cable. This advantageously tends to provide that a person closing the door before the timer is unwound does not need to manually trigger rewinding of the cable. In other embodiments, the door closer does not comprise an override system or V-shaped grooves for the automatic rewinding of loose cable if the door is closed before the timer has unwound. Also in other embodiments, the door closer comprises a different override system or a different system for rewinding loose cable into the door closer. For example, in other embodiments, the door closer comprises a manual override system, e.g. a system in which a person manually triggers the release of the braking mechanism when they close the door before the timer has wound down. In yet further embodiments, automatic triggering of the release of the braking mechanism is provided dependent upon a tension in the cable, however the particular way in which the release of the breaking is provided is different to that described above.

In the above embodiments the sprag couples the brake wheel to the third shaft as described above. This provides that one-way rotation of the second pulley is permitted as the cable is pulled from the door closer and the brake lever is engaged with the brake wheel, and also that rotation of second pulley caused by the spring balance winding in the cable is opposed whilst the brake lever is engaged with the brake wheel. However, in other embodiments this above described functionality may be provided by a differently configured system. For example, in other embodiments the brake wheel is fixed to the third shaft and the second pulley is mounted to the second shaft via a sprag. This sprag provides that rotation of the second pulley in a clockwise direction (when view from above as in Figure 2) relative to the second shaft is permitted. Also, this sprag provides that rotation of the second pulley relative to the second shaft in an anti-clockwise direction is opposed. Thus, in such embodiments (i.e. in which the brake wheel is fixed to the third shaft and the second pulley is mounted to the second shaft via a sprag), when the brake lever is engaged with the brake wheel, the unwinding of the cable from the spring balance (i.e. the opening of the door) is permitted, but the re-winding of the cable back into the door closer by the spring balance (i.e. the closing of the door by the door closer) is opposed.

In the above embodiments, the cable couples the spring balance to the sliding door, and allows a cable pulling system, e.g. the above described spring balance, to pull the sliding door, at least when not hindered. The terminology "cable" is used herein to refer to any type of rope, cord, chain etc. that can provide the above described functionality. For example, in some embodiments the cable 12 is a chain. In such embodiments, the first and second pulleys may comprise teeth (i.e. the pulleys are, in effect, gears) that mesh with the links of the cable/chain (this advantageously tends to reduce risks of a cable slipping with respect to a pulley). In other embodiments, the cable comprises a plurality of interwoven metal cable strands.

In the above embodiments, the terminology "path", or "route" of the cable is used. This terminology is used herein to refer to the path over which the cable travels as it is moved (e.g. by the action of opening or closing the door). In the above embodiments the route of the cable is substantially S-shaped as a result of the cable travelling around the first and second pulleys. In other words the cable's route is defined by objects (pulleys in this embodiment) that are on the route of the cable and that provide a point or points about which the route of the cable may be changed or bent. For example, in the above embodiments the first and second pulleys are on the route of the cable, the pulleys provide points at which the route of the cable is bent, and the cable passes around these pulleys such that the route of the cable describes an "S").

In other embodiments, the route of the cable may be any appropriate shape. The shape of the route of the cable in other embodiments may be defined by any number of pulleys, rollers, and/or any other appropriate component or item, placed on the route of the cable. The terminology "placed on the route of the cable" is used herein to refer to an item that is placed sufficiently proximate to the cable to have an effect on the shape and/or direction of the route of the cable. Thus, an item or component that is on the route of a cable is one that defines the shape and/or direction of the route to some extent. In other words an item or component that is on the route of a cable is one that, were it not present, the shape and/or direction of the route of the cable would be substantially different to the shape and/or direction of the route if the item is present on the route.

As mentioned above, in the above embodiments, the chassis of the door closer is attached to a wall proximate to the sliding door. The sliding door is moveable (i.e. to open and close the door) relative to the wall. Thus, the chassis of the door closer is positioned at an anchor point, or a fixed point, and the sliding door is moveable relative to this anchor point. Since the spring balance is fixed relative to the chassis, this provides that the sliding door is moveable relative to the spring balance (and can therefore be moved by a force applied to the sliding door by the spring balance). In other embodiments, the spring balance (or other cable pulling system) may be at an anchor point that is not on a wall. For example, the anchor point may be a point on a vehicle (e.g. a refrigerated lorry), that a sliding door (of the vehicle) is moveable with respect to. In other embodiments, the anchor point, at which the cable pulling system is mounted, is a different point with respect to which the sliding door is moveable. Also, in other embodiments the chassis of the door closer and/or the cable pulling system may be mounted on the sliding door, and the free end of the cable (i.e. a point on the cable that is pulled towards the cable pulling system) is attached to an anchor point (with respect to which the sliding door is moveable).

Claims

1. Apparatus for use with a sliding door, the sliding door being suitable for human and/or vehicular access, the apparatus comprising:

a first system; and a second system; wherein

the first system is for operating on a cable, the cable being from a cable pulling system to either the sliding door or an anchor point;

the first system may be changed between a first condition and a second condition; the first condition substantially permits movement of the cable by the cable pulling system; the second condition substantially opposes movement of the cable by the cable pulling system;

the second system is arranged to change the first system from the second condition to the first condition after a time period; and

the second system comprises a mechanical timer for timing the time period.

2. Apparatus according to claim 1 , wherein the first system comprises a pulley for acting on the cable.

3. Apparatus according to claim 2, wherein the second condition is provided by a braking mechanism that is applied to substantially prevent the pulley from allowing the cable to be moved along the route by the cable pulling system.

4. Apparatus according to claim 3, wherein the braking mechanism comprises a brake lever.

5. Apparatus according to claim 4, wherein:

the braking mechanism further comprises a brake wheel;

the first condition is imposed when the brake lever is not engaged with the brake wheel; and

the second condition is imposed when the brake lever is engaged with the brake wheel.

6. Apparatus according to claim 5, wherein:

the pulley and a first gear are coaxial;

the brake wheel and a second gear are coaxial; and

the first gear meshes with the second gear.

7. Apparatus according to claim 6, wherein a gear ratio between the first gear and the second gear is 1 :3.

8. Apparatus according to claim 6, wherein a gear ratio between the first gear and the second gear is 1 :1.

9. Apparatus according to any of claims 1 to 8, wherein the timer is set by an action of moving the cable in a direction opposite to the direction of travel resulting from the cable being pulled by the cable pulling system.

10. Apparatus according to claim 9, wherein: the timer being set by an action of moving the cable in a direction opposite to the direction of travel resulting from the cable being pulled by the cable pulling system comprises the timer being wound; the timer unwinds from a wound state to an unwound state after a time period;

the second system is arranged to provide that the first system is in the first condition when the timer is in the unwound state, and that the first system is in the second condition when the timer is not in the unwound state.

1 1. Apparatus according to claim 10, wherein winding of the timer past the wound state corresponding to the time period is opposed by an action of a slip clutch.

12. Apparatus according to claim 10 or 11 , wherein unwinding of the timer is facilitated by an action of a wrap spring clutch.

13. Apparatus according to any of claims 1 to 12, wherein a maximum value of the time period may be predetermined or selected.

14. Apparatus according to any of claims 2 to 13, wherein the unwinding of the timer from a wound state to an unwound state moves a cam from a first position to a second position.

15. Apparatus according to claim 14, wherein movement of the cam from the first position to the second position comprises rotation of the cam about its axis.

16. Apparatus according to claim 14 or 15, wherein:

in the first position, the cam is not engaged with the brake lever; and in the second position, the cam is engaged with the brake lever.

17. Apparatus according to any of claims 14 to 16, wherein the first position of the cam is such that the brake lever is engaged with the brake wheel, and the second position of the cam is such that the brake lever is not engaged with the brake wheel.

18. Apparatus according to any of claims 14 to 16, wherein the cam is coaxial with the slip clutch.

19. Apparatus according to any of claims 14 to 17, wherein the cam is coaxial with the wrap spring clutch.

20. Apparatus according to any of claims 1 to 19, further comprising means for substantially permitting movement of the cable by the cable pulling system, before the timer period has lapsed, dependent upon an amount of tension in the cable.

2 . Apparatus according to claim 20, wherein:

the means comprising a pulley having a V-shaped groove around at least a portion of its circumference; and

the cable travels around at least a portion of the V-shaped groove.

22. Apparatus according to claim 21 when dependent on claim 2, wherein the pulley and the pulley having a V-shaped groove are the same pulley.

23. Apparatus according to any of claims 20 to 22, wherein the means comprises an override system arranged to change the first system from the second condition to the first condition dependent upon an amount of tension in the cable.

24. Apparatus according to claim 23, wherein the override system comprises a spring loaded lever arranged to change the first system from the second condition to the first condition when the tension in the cable falls below a given level.

25. Apparatus according to any of claims 1 to 24, wherein the pulling of the cable by the cable pulling system provides automatic closing of the sliding door.

26. Apparatus according to any of claims 1 or 25, wherein the cable pulling system is a winding mechanism for winding the cable.

27. Apparatus according to claim 26, wherein the winding mechanism is arranged to automatically wind the cable.

28. Apparatus according to any of claims 1 to 27, the apparatus further comprising the cable and the cable pulling system.

29. Apparatus according to any of claim 28, wherein the cable pulling system is mounted at the fixed anchor point such that the cable is from the cable pulling system to the sliding door.

30. Apparatus according to claim 28, wherein the cable pulling system is mounted on the sliding door such that the cable is from the cable pulling system to the anchor point.

31. Apparatus according to any of claims 1 to 30, wherein the cable is moved by a certain extent in a direction opposite to the direction of travel resulting from the cable being pulled by the cable pulling system by an action of opening the sliding door.

32. Apparatus according to any of claims 1 to 31 , wherein the time period is dependent on an extent of travel of the cable in a direction opposite to the direction of travel resulting from the cable being pulled by the cable pulling system.

33. Apparatus according to any of claims 1 to 32, wherein:

the cable is moved by a first extent of travel in a direction opposite to the direction of travel resulting from the cable being pulled by the cable pulling system; and

after being moved by the first extent of travel, the cable is moved by a second extent of travel in the direction opposite to the direction of travel resulting from the cable being pulled by the cable pulling system; and

a time period corresponding to the first extent is different to a time period corresponding to the second extent.

34. Apparatus according to claim 33, wherein the time period corresponding to the first extent is greater than the time period corresponding to the second extent.

35. Apparatus according to claim 33 or 34, wherein the time period corresponding to the second extent is zero.

36 Apparatus according to any of claims 1 to 35, wherein the cable comprises metal cable strands.

37. Apparatus according to any of claims 1 to 36 wherein the cable is a chain.

38. Apparatus according to any of claims 1 to 37, wherein the sliding door is suitable for access to one or more of the following (i) a cold room, (ii) a refrigerated room, (iii) a freezer room, (iv) a refrigerated lorry.

39. A sliding door closing device comprising apparatus according to any of claims 1 to 38.

40. A sliding door assembly comprising a sliding door for human and/or vehicular access, and the door closing device according to claim 39.