Abstract:
A push plate assembly ( 10 ) that may be used for driving a bolting mechanism is disclosed. The push plate assembly ( 10 ) may he included as part of a push pad assembly or panic bar assembly, such as may be fitted to single or multipoint bolt mechanisms, for example, those fitted to emergency exit doors. The push plate assembly comprises a housing ( 32 ), a push plate ( 36 ), a slide plate ( 45 ) and a drive cam ( 55 ). The drive cam ( 55 ) is arranged to rotate within the housing so as to rotationally drive a bolt mechanism.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a push plate assembly, for example, to drive a bolting mechanism. The push plate assembly may be included as part of a push pad assembly or panic bar assembly. In particular, but not exclusively, the invention relates to a push plate assembly that may be fitted to multipoint or single point bolt mechanisms such as those fitted on emergency exit doors. 
       DISCUSSION OF THE PRIOR ART 
       [0002]    Commonly, multi-point or single point bolting mechanisms are used on emergency exit doors of buildings, as shown in  FIG. 1 . These bolting mechanisms often include a panic bar  2  for release of the bolting mechanism  4  during an emergency, as shown in  FIG. 1 . The panic bar  2  provides a means of releasing the bolting mechanism  4  that is easy and quick to operate. In emergency situations, the door must be unbolted rapidly to allow persons to escape through the door way. If the bolt release mechanism uses a door handle, the persons trying to escape must first locate the door handle, and then turn it in the correct direction to open the door. A panic bar requires less time to locate as it is generally of the same width of the door, and merely requires a pushing motion towards the door to release the bolting mechanism. This can be especially useful in situations where visibility is poor, such as in smoke filled buildings. Moreover, a panic bar can be easily operated by young children and the elderly. 
         [0003]    In some locations, a push pad is sufficient. This also requires a pushing motion to release the bolting mechanism, but the actuator is smaller and limited to a pad rather than a bar. 
         [0004]    Push pad and panic bar bolt release mechanisms are fitted to bolting mechanisms on doors and other openings, and are required to be tailored to meet the opening direction of the door. For example, left hand and right hand opening doors will require bolting mechanisms and push pads/panic bars that are also left handed or right handed to match the door. Prior art systems require different handed bolting mechanisms and push pad/panic bars, or at least a number of additional components to allow conversion of a dual handed unit to operate in both right and left handed configurations. 
         [0005]    As identified above, push pads and panic bars should be easy to operate by everyone, including the elderly, disabled and young children. Hence, any reduction in the force required to operate the push pad or panic bar is desirable. Such reductions in operating force, must not be achieved at the expense of reduced reliability. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention seeks to overcome problems of the prior art. Accordingly, the present invention provides a push plate assembly for rotationally driving a bolt mechanism, the push plate assembly comprising: a housing, a push plate rotatably coupled to the housing so as to rotate when pushed towards the housing, a slide plate mounted within the housing to slide when driven by rotation of the push plate, and a drive cam arranged to rotate within the housing when driven by the slide plate so as to drive the bolt mechanism. 
         [0007]    The push plate may comprise a tang or shoulder adapted to bear against a surface of the slide plate so as to drive the slide plate on rotation of the push plate. 
         [0008]    The drive cam may be arranged to rotate within the slide plate and bear upon a cammed surface of an aperture within the slide plate. The cammed surface may be a flat surface of the slide plate upon which the cam bears. 
         [0009]    The axis of rotation of the drive cam may be perpendicular to the direction of sliding of the slide plate. 
         [0010]    The axis of rotation of the drive cam may pass through or intersect the plane of the slide plate. 
         [0011]    The rotation of the push plate may be about an axis substantially perpendicular to the axis of rotation of the drive cam. 
         [0012]    The push plate may be hinged by a pin passing through one or more holes in each of the housing and the push plate. 
         [0013]    The drive cam may include an aperture adapted to receive a shaft or spindle for driving the bolt mechanism. The aperture may be adapted to receive the shaft or spindle at two orientations, the two orientations arranged for reversible drive of a bolt mechanism. By reversible we mean that the assembly may be reconfigured to operate on either a left hand opening door or a right hand opening door. The aperture may be comprised of two square apertures offset by an angle about the rotation axis of the drive cam. 
         [0014]    The push plate may be rotatably coupled to the housing by a pivot comprising a first bearing. The first bearing may be a sleeve bearing. The bearing reduces the force required to actuate the push pad and also may also increase the life of the assembly. 
         [0015]    The drive cam may be rotatably coupled to the housing by a bearing assembly. 
         [0016]    The drive cam may comprise a crank pin arranged to be driven by the slide plate to rotate the drive cam. The crank pin may be rotatably coupled to the drive cam via a bearing. 
         [0017]    Advantageously, less than 45° rotation of the push bar may provide greater than 45° of rotation of a shaft of the bolt mechanism. 
         [0018]    There is also provided a push pad assembly, and a panic bar assembly comprising the push plate assembly. The push pad assembly includes the push plate assembly and a push bar. The panic bar assembly includes the push plate assembly and a bar for pushing. In addition, a bolting mechanism may comprise the push plate assembly, push pad assembly, or panic bar assembly. The bolting mechanism may comprise one or more bolts slideable from a thrown position to a retracted position by pressing the push plate. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings in which: 
           [0020]      FIG. 1  shows a panic bar of the prior art mounted to a door; 
           [0021]      FIG. 2  shows a perspective view of the push pad assembly of the present invention; 
           [0022]      FIG. 3  shows the push pad of  FIG. 2  fitted to a multipoint bolting mechanism; 
           [0023]      FIG. 4  is an exploded view of the push pad assembly of  FIG. 2 ; 
           [0024]      FIG. 5  is a perspective view of the drive cam of the push pad assembly of  FIG. 2 ; 
           [0025]      FIGS. 6   a  and  6   b  are rear perspective views of the push pad assembly (housing backplate not shown) with the push pad in the raised and lowered positions respectively; 
           [0026]      FIGS. 7   a  and  7   b  are schematic diagrams showing the movement of the drive cam and slide plate of the push pad for use on a left handed door; 
           [0027]      FIG. 8   a  and  8   b  are schematic diagrams showing the movement of the drive cam and slide plate of the push pad for use on a right handed door; 
           [0028]      FIG. 9  is a schematic diagram showing the positions of the drive cam and aperture in the cam for left and right handed operation; 
           [0029]      FIG. 10  is a perspective view of a panic bar assembly of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0030]    Preferred embodiments of the push plate assembly of the present invention are a push pad assembly, and panic bar assembly. 
         [0031]      FIG. 2  shows the push pad assembly  10 .  FIG. 3  shows the push pad assembly  10  mounted to a multipoint bolting mechanism  20 . The multipoint bolting mechanism  20  is shown as an example. The push pad may be used with other bolting mechanisms and in particular, single point bolting mechanisms. 
         [0032]      FIG. 4  shows an exploded view of the push pad assembly  10 . The push pad assembly  10  comprises a housing  32  together with a housing backplate  34 . In the embodiment shown, the housing backplate  34  is longer than the housing  32 . The parts  34   a  extending beyond the end of the housing  32  include mounting holes  35  for mounting the push pad assembly  10  to the bolting mechanism, as shown in  FIG. 3 . Alternative embodiment do not include the parts  34   a,  and a different mounting configuration may be used. 
         [0033]    The push pad assembly  10  further comprises a push pad  36  pivotally coupled to the housing by pin  37 . The push pad  36  is extended in two directions from the pivot. That is, the push pad  36  extends away from the housing to provide a means for operating the push pad assembly. The push pad  36  also comprises a drive shoulder  38  which extends into the housing  32 . The push pad  26  may also comprise various front  40  and side  41  cover plates. These may be manufactured or painted in a colour that is readily apparent to people nearby. Commonly, green is used to indicate emergency exits. The cover plates may be manufactured from plastic or other durable material. 
         [0034]    As mentioned above, the push pad  36  may be mounted to the housing  32  with a pin  37  to provide a pivotable coupling. Additionally, sleeve bearings  43  may be used between the pin  37  and housing  32  to reduce the frictional force required for rotation of the push pad. The reduced friction may also help to increase the lifetime of the push pad assembly  10 . 
         [0035]    There is also provided a slide plate  45  in the housing. In the present embodiment, the slide plate is formed in a rectangular ring, the bottom side  46  extending out of the plane of the ring. The top side  47  of the ring is located above, but resting on, the drive shoulder  38  of the push pad  36 . 
         [0036]    The backplate  34  has attached thereto a bearing assembly  50  enclosed by support ring  52 . The support ring  52  is fixed to the backplate  34  by screws  53 . The bearing assembly  50  holds the drive cam  55 , while allowing rotation of the cam about an axis through the centre of the bearing assembly. The drive cam  55  is a push fit in the bearing assembly  50 , and retained by a circlip (not shown). 
         [0037]      FIG. 5  shows the drive cam  55  in more detail. The drive cam  55  is comprised of an aperture  58 , a cam lobe  60 , and a crank pin  62  mounted on the cam lobe  60 . When the push pad assembly  10  is fitted to a bolting mechanism, the aperture  58  holds a spindle for driving the lock mechanism. Such spindles usually have a square cross-section, and hence the aperture  58  may be square. Additionally, the aperture  58  may be comprised of two offset square apertures. In such a case, the two apertures are centred on a common axis A, but offset by an angle. The offset apertures are used when the push pad assembly is configured for reversible use. This is described in more detail below. 
         [0038]    The crank pin  62  mounted on the cam lobe  60  includes bearings to allow the curved outer surface of the crank pin  62  to rotate. 
         [0039]    In the push pad assembly  10 , the crank pin  62  of the drive cam  55  rests against the upper surface of the bottom side  46  of the slide plate  45 . 
         [0040]      FIG. 6  shows the assembled push pad assembly  10  with the backplate  34  removed to show the internal operation of the assembly.  FIG. 6   a  shows the push pad assembly  10  with the push pad  36  raised. This is the position of the push pad  36  when the bolting mechanism to which the push pad is attached is in the thrown or bolted position, for example when securing a door closed.  FIG. 6   b  shows the push pad in the lowered position, such as when the push pad has been operated to release the bolting mechanism and open the door. 
         [0041]    The operation of the push pad assembly  10  will now be described. In the raised position shown in  FIG. 6   a,  the slide plate  45  is in a lowered position, and may rest on the bottom of the inside of the housing  32 . This is also shown schematically in a rear plan view in  FIG. 7   a.  The shoulder  38  of the push pad  36  is engaged under the top side of the slide plate. The drive cam  55  is oriented such that the aperture  58  for receiving a shaft or spindle of the bolting mechanism (not shown), is in a locked or thrown position, such as when securing a door closed. In this position, the crank pin  62  of the drive cam  55  rests on the top surface of the bottom side  46  of the slide plate  45 . 
         [0042]    In  FIG. 6   b,  the push pad  36  is shown in the lowered position representing the position in which the bolting mechanism has been released. The push pad  32  has turned about the pivot  37 , thereby raising the shoulder  38  of the push pad  36 . As mentioned above, the slide plate  45  is engaged with the shoulder of the push pad  36 . Hence, the slide plate  45  has been raised with the shoulder  38 . This is also shown schematically in  FIG. 7   b.  The crank pin  62 , which is resting on the bottom side  46  of the slide plate, is also moved. The drive cam  55  has been rotated by the movement of the slide plate, thereby allowing the crank pin  62  to move upwards with the slide plate. Since the drive cam  55  has been rotated, the aperture  58  for holding the spindle (or shaft) of the bolt mechanism has also rotated which may thereby release the bolts and allow a door to open. 
         [0043]      FIG. 8  shows schematically how reorienting the drive cam  55  allows the push pad assembly to be reversed. For example, if  FIGS. 7   a  and  7   b  show the operation of the assembly on a left hand opening door, then by reorienting the drive cam  55  the push pad assembly may be used on a right hand opening door. This allows the push pad to be supplied as one unit that is reversible and can be fitted to either left hand or right hand opening doors by simply reorienting the cam  55 . No additional or alternate components are required. 
         [0044]    To change the operation of the push pad  10  from being suitable for operation on a left hand opening door to a right hand opening door, the drive cam  55  should be rotated from being on the right side of the aperture  58 , as shown in  FIGS. 7   a  and  7   b,  to be on the left side of the aperture  58 , as shown in  FIGS. 8   a  and  8   b.  This operation should be performed prior to fitting the push pad assembly  10  to the bolting mechanism  20 . The rotation of the drive cam  55  to change from left handed to right handed operation may be achieved by inserting a spindle into the aperture  58  and turning the drive cam through between 180 and 270°. Once the rotation has been effected, the push pad assembly  10  may be fitted to the bolting mechanism  20 . 
         [0045]    As mentioned above the aperture  58  may be comprised of two offset squares. This was shown in  FIG. 5  and is also illustrated schematically in  FIG. 9   b.  When fitted to the bolting mechanism  20 , the spindle of the bolting mechanism may have a rest bolted (or thrown) position with the square sides of the cross-section of the spindle aligned vertically and horizontally. Hence, the aperture  58  of the drive cam  55  should be correspondingly aligned when the push pad is in the raised position.  FIG. 9   a  shows schematically the orientation of the drive cam  55  and aperture  58  for a left hand opening door. As mentioned above, rotation of the drive cam  55  by between 180 and 270° (about axis A) converts the push pad assembly operation to that for a right hand opening door. However, as shown in  FIG. 9   b,  this rotation may result in the aperture  58  now being at angle to the vertical and horizontal. If the spindle for the left hand opening door also requires the square aperture to be aligned vertical and horizontal, then the aperture is in the wrong position. To overcome this effect, the aperture comprises a second square  58   a  offset by an angle to the first, as shown in  FIG. 9   b.  The angular offset between the two squares  58  and  58   a  is determined by the starting position of the cam at the two positions shown in  FIGS. 9   a  and  9   b.  The angular offset will be 2θ, where θ is the angle between the start position (that is the position of the drive cam with the push pad  36  raised) and the vertical. In some case, this will be 45°, in other cases a different offset will be used. 
         [0046]    The above described push pad assembly  10  also has an advantage in that the amount of rotation of the drive cam and hence, the spindle of the bolting mechanism, is increased over prior art devices. In particular, for movement of the push pad  32  from the raised position to the lowered position, the push pad rotates by a given angle about its pivot  37 . In the above described embodiments, the resulting amount of rotation of the drive cam is greater than the amount of rotation of the push pad. For example, a 45° rotation of the push pad from the raised position to the lowered position results in a 57° rotation of the drive cam  55  and the spindle of the bolting mechanism. For other embodiments, the amount of rotation of the drive cam may be changed by adjusting the relative position of the crank pin. For example, for the same movement of the slide plate, a crank pin located closer to the crank rotation axis may achieve increased rotation of the drive cam  55 . 
         [0047]    Once the door has been released the push bar  36  will be returned to its raised position by the spring loading of the bolting mechanism. 
         [0048]    The above described embodiments may incorporate three different bearings: sleeve bearing  38  used between the pin  37  and housing  32  to reduce friction during the rotation of the push pad  36 ; bearing assembly  50  for smooth rotation of the drive cam  55  and spindle; and bearings to allow rotation of the outer surface of the crank pin  62  as it moves against the slide plate  45 . The effect of these bearings is to reduce friction and improve the lifetime of the push pad assembly. Moreover, the combination of the reduced friction, and the effect of greater rotation of the bolt spindle for a given movement of the push pad means the embodiments described are easier to use by the disabled, elderly and children. The above described embodiments have a release pressure significantly below European standards for such devices. 
         [0049]      FIG. 10  shows a panic bar assembly  80 . The mechanism and operation of the panic bar assembly  80  is very similar to that of the push pad assembly  10 . The panic bar assembly  140  comprises two housings  32  and  132 . The housing  32  and components contained therein are the same as for the push pad assembly  10 . The second housing.  132  is provided at a distance from the first housing  32 . The second housing also comprises a push pad  136 . The two push pads are linked by bar  140 . The second housing  132  may contain another set of the components contained in the first housing  32 . Alternatively, since the first housing contains the mechanism that will be used to drive the bolting mechanism  20 , the second housing  132  and second push pad  136  may merely support the distal end of the bar. 
         [0050]    When fixed to the bolting mechanism on a door or other opening, the first housing is fitted directly to the bolting mechanism. The second housing  132  will be fitted toward the opposing side of the same face of the door. The second housing  132  will require a spacer between it and the door to match the thickness of the bolting mechanism to which the first housing is fitted to. The spacer will maintain the bar  140  an even distance from the door along the length of the bar. 
         [0051]    The panic bar assembly  80  may be reconfigured to operate on a left or right hand opening door in the same manner described above for the push bar assembly. Additionally, the relative positions of the first housing and second housing must be swapped to ensure the first housing  32  (containing the operating mechanism) is on the correct side of the door for the bolting mechanism. This can be done by removing the fixings holding the bar  140  to the push pads  32  and  132  and swapping the push bar assemblies over. 
         [0052]    The person skilled in the art will readily appreciate that various modifications and alterations may be made to the above described push pad and panic bar assemblies without departing from the scope of the appended claims, for example, different bolting mechanisms may be used, such as a single point bolting mechanism, or the bolting mechanism may be on a different leaf to an emergency exit door. Variations in the actual shapes of the parts such as the cam and shaft/spindle may also be made without diverging from the general scope of the present invention.