AU2012101071A4 - Secure under-door seal - Google Patents

Abstract

Abstract An under-door seal to be mounted at the foot of a door (10) has a sealing member (23) positioned between a back plate (21) and a front plate (22). The sealing member, back plate and front plate are all horizontally elongate, of length substantially equal to the width of the door. The front plate (22) is connected to the back plate (21). The sealing member (23) is movable downwardly, from its "door open" position, relative to the front and back plates by the rotation of cams (45) that (a) are mounted on respective axles (46) that extend horizontally from the back plate (21), and (b) are moved by pegs (53) that fit into cavities (49) in the cams. The pegs (53) extend horizontally from a control rod (50). The lower surface of each cam (45) is in contact with the upper surface of a horizontal bar (32) of the sealing member (23) when the sealing member is in its "door open" position. The underside of this bar (32) forms a seal with the surface under the door (10) when the cams (45) are rotated as the control rod (50) is moved when one end (55) of the control rod, that projects from the side face of the sealing member (23), contacts the door frame (11) as the door (10) is closing and is moved as the door closure is completed. Helical springs (60, 61), each mounted between (a) a horizontal pin (35, 36) in the sealing member (23) and (b) a horizontal pin (62, 63) extending from a respective block (64) that projects from the back plate (21) towards the front plate (22), provide an upward force on the sealing member when it has been moved downwardly. This upward force acts to return the sealing member to its "door open' position when the door (10) is opened.

Description

1 Regulation 3.2A AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION (Innovation Patent) Name of Applicant/Nominated Person: Trevor David Leisk Address for Service: Davies Collison Cave, Patent Attorneys 1 Nicholson Street, MELBOURNE, Victoria, 3000. Invention title: "Secure under-door seal" The following statement is a full description of this invention, including the best method of performing it known to me: 2 Technical field. This invention concerns door seals. More particularly, it concerns apparatus that prevents access to a room via the underside of a door. It was conceived for use with a door that provides an entry point for a secure room (for example, 5 a "Type 1 Secure Room"). Although this invention does not establish a seal that is actually underneath a door, common usage of the term "under-door seal" shows that the present invention is a mechanisms that is correctly termed an "under-door seal" 10 Notwithstanding the security need that led to the conception of the present invention, the under-door seals described and claimed in this specification may be used with any door requiring a good under-door seal. Preliminary note. 15 In this specification, including the claims, "directional" terms (such as "vertical", "horizontal", "top", "bottom", "side", "upper", "lower", and the like) will be used in the sense that these terms would have with reference to an under-door seal that is positioned as shown in Figures 1 and 2 of the accompanying drawings. 20 Background to the invention. Various mechanisms for providing a seal at the bottom of a door have been used over many years. Included in such seals are the following. 1. The old-fashioned elongate cloth (or other material) bag, filled 25 with a suitable material, often called a "sausage", is still used today to stop drafts entering a room in winter. 2. The well-known (and long used) door seal that comprises two planar metal strips that extend over the width of a door, with the 3 upper strip secured (usually screwed) to the door, and with the elongate upper edge of the lower strip connected to the upper strip by a hinge. The lower metal strip is spring-biased so that its plane is out of alignment with the plane of the upper strip, and 5 has a strip of rubber, neoprene or the like extending from its lower edge. This rubber (or the like) strip is forced into contact with the surface of the door step or floor, when the door is closed, by a disc (or a pair of discs) mounted on the door frame. 3. The more complex, and recently developed, pin-operated, spring 10 loaded, under-door acoustic seals that can be obtained, for example, from Raven Products Pty Ltd, of Lonsdale, South Australia (as "Raven Door Seals"), or from Kilargo Pty Ltd, trading as Lorient Australia, of Banyo, Queensland (as "Lorient Door Seals"). Using these door seals, the establishment of the 15 acoustic seal is triggered when the door is closed. Disclosure of the invention. It is an objective of the present invention to provide an under-door seal that, when the surface under the door is flat (whether it is the surface of a door step, 20 a floor or a threshold plate), provides a seal that is such that it is not possible to insert a wire carrying a small microphone or a small camera lens between the under-door surface and the sealing member of the under-door seal. This objective is achieved by a vertically moveable, cam-operated, sealing 25 member that is positioned between two plates, one of which I have called a "back plate" (this plate being a plate that is mountable on a panel of a door), and the other of which I have called a "front plate". Each plate is horizontally elongate, and its elongate length is essentially equal to the width of the bottom of the door onto which the under-door seal is to be mounted.

4 The sealing member comprises a horizontal bar (conveniently, of rectangular cross-section) the lower surface of which will normally be planar, so that the lower surface can form a seal with the flat surface under the door when the door is closed. The bar has a length equal to the length of the front and back 5 plates. A pair of blocks - which I have called "arms" - extend upwardly, above the end regions of the bar. A respective short pin extends horizontally from each arm, above the top surface of the bar. Each arm has a vertical slot in it. A respective post that extends horizontally from the back plate, at right angles to the elongate direction of the back plate, is a sliding fit within these 10 vertical slots. The front plate is a flat plate and has horizontally extending apertures in it, through which respective screws may pass to be screwed into correspondingly located, cylindrical, threaded cavities in the back plate, to attach the front is plate to the back plate with the sealing member sandwiched between the plates (but with the sealing member able to move upwardly and downwardly). The sealing member is moved up and down by a combination of at least one cam and a pair of helical springs. (In principle, one cam can perform this 20 action, but in practice, at least two, and preferably three, cams will be used.) Each cam is mounted on a respective axle that extends horizontally from the back plate, so that at least part of the lower surface of each cam is in contact with the upper surface of the bar of the sealing member. Each cam has a cylindrical cavity formed in its upper region, with the axis of each such cavity 25 being horizontal and parallel to the axes of the axles on which the cams are mounted. Rotation of the cams about their axles is controlled by a horizontal rod (which I have called the "control rod") that has two parts. The first part has a number of pegs - equal to the number of cams - extending horizontally from it. Each peg is a sliding fit within the cylindrical cavity in the upper 5 region of a respective cam. The second part may comprise a rod of circular cross-section, that is threaded over at least a length of the end thereof that is remote from the first part. (The second part of the control rod could be a threaded elongate stud.) 5 The second part of the control rod passes through a horizontal aperture in one of the arms of the sealing member. A door frame contacting member may be securely mounted on the free end of the second part of the control rod (that is, the end of the second part that is remote from the first part of the control 10 rod). When the door on which the under-door seal has been mounted is nearly closed, the free end of the second part (or the door frame contacting member if it is present) comes into contact with the door frame or a plate attached to the door frame. Continuing the closure of the door moves the entire control rod horizontally. The horizontal movement of the pegs on the is control rod moves (rotates through a small angle) the cams. This movement of the cams pushes the sealing member downwardly, so that the lower surface of the sealing member contacts the flat surface under the door when the door is fully closed. 20 The two helical springs that, with the cams, control the vertical movement of the sealing member are compression springs. One end (the first end) of each spring fits over a respective one of the pins extending from the arms of the sealing member. The other end of each spring fits over a second pin that (a) extends horizontally from a respective one of a pair of blocks that project out 25 from the back plate, towards the front plate, and (b) when the door is open, has an axis that is substantially co-linear with the axis of the pin on the arm of the sealing member over which the first end of the spring has been fitted. When the door is open, these springs have their axes horizontal. When the sealing member is pushed downwards by the movement of the cams, the axis 6 of each helical spring is no longer linear but becomes either generally arcuate or has the shape of a shallow letter S. This distortion of the helical springs results in each spring providing an upwards force on the pins on the arms of the sealing member. When the door that has been closed is opened, this 5 upwards force lifts the pins on the arms of the sealing member and moves the sealing member upwards until the axis of each helical spring is again linear and substantially horizontal. This upwards movement of the sealing member moves the cams, and thus the pegs on the control rod, which moves (since the pressure on the free end of the second part of the control rod 10 has been removed) to its "open door" position. Thus, according to the present invention, an under-door seal mechanism for attachment to a door comprises: 1. a back plate adapted to be affixed to the lower region of said door 15 and a front plate; said back plate and said front plate being horizontally elongate, the length of each plate in the horizontal direction being substantially equal to the width of said door; said front plate having horizontal apertures therein through which respective screws or bolts pass to be screwed into 20 correspondingly located threaded horizontal cavities in said back plate; 2. a sealing member positioned between said front plate and said back plate; said sealing member comprising a horizontally elongate bar having a length substantially equal to the elongate 25 length of said back plate and said front plate; the underside of said sealing member having a shape such that, when in contact with the surface underneath said door when said door is closed, forms a seal with said surface; 3. first and second arms extending upwardly above said bar, over 7 respective end regions of said bar; each of said arms having a vertical slot therein to receive a respective post that extends horizontally from said back plate; each said post being a sliding fit within its associated slot; each of said arms also having a 5 respective horizontal pin extending above said bar; said first arm having an aperture therethrough in the elongate direction of said bar; 4. at least one axle on said back plate extending horizontally towards said front plate, and a cam member mounted on said, or 10 each, axle; said, or each, cam member comprising a disc having planar vertical faces separated by an edge surface, the lowermost part of which is in contact with the upper surface of said bar; said, or each, cam member having a cylindrical cavity extending horizontally into the upper region of the cam member from the 15 face thereof that is remote from said back plate; 5. an elongate control rod having a first part and a second part; said first part having at least one peg extending horizontally therefrom into, and being a sliding fit within, said cylindrical cavity in the upper region of the (or a respective) cam member; said second 20 part comprising a rod that is an extension of said first part; said second part passing through said aperture in said first arm and having a short length thereof extending beyond the end of said sealing member; 6. first and second blocks projecting from said back plate towards 25 said front plate; said first block having an aperture therein extending horizontally, parallel to the elongate direction of said back plate, in a position such that said aperture in said first block is aligned horizontally with said horizontal aperture in said first arm, so that said second part of said control rod passes through 8 said aperture in said first block; a respective pin extending horizontally from each said block (a) in a direction towards an associated one of said pins extending from said arms above said bar, and (b) below the level of said aperture in said first 5 block; and 7. first and second helical springs, the ends of said spring being positioned around respective first and second pins, each of said first pins being one of said pins extending horizontally from said first and second arms, and each of said second pins being one of 10 said pins extending horizontally from said first and second blocks. Preferably, as indicated above, a door frame contacting member may be securely mounted on the free end of the second part of the control rod (that 15 is, the end of the control rod that projects beyond the end of the sealing member). Most preferably, the second part of the control rod comprises a rod of circular cross-section that is threaded over at least a length of the end thereof that is remote from the first part, and the door frame contacting member is an internally threaded ferrule that is screwed onto the threaded 20 free end of this rod of circular cross-section, for the required distance, and is then locked in place by a grub screw that is screwed into the ferrule. Preferably, the back plate of the under-door seal is milled out around each axle, to form a recessed region in which part of the disc the constitutes the cam 25 member lies. If these recessed regions are present, each cam must have a thickness such that part of the edge surface of the cam contacts the upper surface of the bar of the sealing member. The back plate may have a top region with apertures in it, through which 9 screws may pass to attach the back plate to a panel of the door. Preferably, a cover member is fitted over the under-door seal once the under door seal has been mounted on a door. If the surface under the door is not 5 flat enough to provide a satisfactory seal when a unit of the present invention is mounted on the door, a steel threshold plate may be provided, optionally with an elongate slot therein to receive an elongate projection from the underside of the sealing member. 10 Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings. Brief description of the drawings. Figure 1 is a partly schematic perspective sketch of the lower part of a door to 15 which an under-door seal, in accordance with the present invention, has been attached. Figure 2 is a partly schematic, exploded view sketch of the components of an under-door seal constructed in accordance with the present invention. 20 Detailed description of the illustrated embodiments. Figure 1 depicts a door 10 mounted on a door frame 11 by hinges 12. If the room to which the door 10 provides access is a secure room, it is unlikely that the simple door 10 illustrated in Figure 1 would be used. More likely, the 25 door would be, for example, a security door having features such as those described in the specification of my Australian patent application No. 2011202561. An under-door seal is mounted on the door 10. The under-door seal shown in Figure 1 has a back plate 21 and a front plate 10 22. A sealing member 23 is positioned between the back plate and the front plate. A door frame contacting member 25 is shown, projecting from the end of the sealing member 23. A cover 24, mounted on the front plate 22, protects the under-door seal. 5 Figure 2 shows the components that, when assembled, form an under-door seal similar to that shown in Figure 1. In Figure 2, the back plate 21 of the under-door seal has a lower portion and 10 an upper portion, the delineation between the two portions (which need not be of substantially the same height) is shown by dashed lines. The upper portion has countersunk apertures 26 to enable screws 27 to be used to mount the back plate 21 at the bottom of one face of the door 10. Other means of mounting the back plate 21 on the door 10 may be used. (For example, 15 screws or bolts passing through the the door 10 may engage with threaded cylindrical apertures or cavities in the face of the back plate 21 that is not visible in Figure 2; with such a mounting arrangement, the upper portion of the back plate 21 will not be needed and the cover 24 can extend over the entire top of the under-door seal.) The elongate (horizontal) length of the 20 back plate 21 and the front plate 22 is equal to the width of the door 10. The front plate 22 has apertures 28 through which screws or bolts 29 can pass to engage with the threads of the internally threaded cylindrical cavities (or apertures) 30, to hold the front plate 22 and the back plate 21 together with the 25 sealing member 23 between these two plates. The sealing member 23 must be able to move up and down short distances relative to the plates 21 and 22 and, if necessary, a low friction surface material may be applied to the elongate vertical surfaces of the sealing member 23, and/or to at least part of the faces of the back plate and the front plate that are alongside the sealing 11 member 23. The sealing member 23 is essentially an elongate horizontal bar 32 with a first arm 33 extending upwards above one end of the bar, and with a second 5 arm 34 extending upwards above the other end of the bar. In Figure 2, the portion of the bar 32 that is between the arms 33 and 34 has a rectangular cross-section. This cross-sectional shape is not essential, and can be varied, provided (a) the underside of the bar 32 has a shape that forms a seal with the surface under the door 10 when the door is closed, and (b) the upper surface of 10 the bar 32 is in contact with the edge surfaces 42 of the cam members 45 (which are described in more detail below). If the surface under the door 10 (for example, a door sill) is not flat, an elongate threshold plate, of steel, may be provided to cover that surface. Such a threshold plate may need to be used with a suitable packing or filler compound under it to ensure that there is no 15 gap below the threshold plate through which a wire may be passed to access the room when the door 10 is closed. The threshold plate may be provided with (a) an elongate groove, into which a strip of steel, projecting from the underside of the bar 32, may be located when the door is closed; or (b) an elongate small hump, to fit against an elongate, inwardly curved, shallow 20 channel, having the cross-sectional shape of a segment of a circular disc, formed in the underside of the bar 32. In another alternative construction, both the threshold plate and the underside of the sealing member 23 are stepped (and preferably, in such an arrangement, the threshold plate has a small downward step, to avoid inadvertent tripping of a person entering the room 25 when the door is open.) The second arm 34 of the sealing member has a pin 36 extending horizontally from it, above the top surface of the bar 32. The first arm 33 has a similar horizontally extending pin 35, and also a vertical slot 37 and an aperture 39, 12 at right angles to each other, extending through it. The second arm 34 has a vertical slot 38, having the same dimensions and position in the arm as the vertical slot 37 in the first arm 33. 5 Horizontal posts 40 and 41, one near each end of the back plate 21, project into (and may pass through) the slots 37 and 38. The posts 40 and 41 serve as locating means for the sealing member 23. They are a sliding fit within the slots 37 and 38 and do not impede the downward and upward movement of the sealing member. The distance between the outer (vertical) surfaces of the arms 10 33 and 34 is equal to the elongate length of the back plate 21 and the front plate 22. The aperture 39 in the first arm 33 has one end of one part of the control rod 50 passing through it, as will be explained in more detail below. 15 When the door 10 is open, the sealing member 23 is at its highest level. When the door 10 is closed, the sealing member is moved downwards to provide a seal with the surface under the door. This movement of the sealing member is effected by - in the Figure 2 embodiment - the rotation of three cam members 20 45, each mounted on a respective axle 46 that extends horizontally from the back plate 21, towards the front plate 22. Each cam member is a non-circular disc having first and second vertical faces 47 and 48, separated by an edge surface 42. The lowest part of the edge surface 42 is in contact with the top surface of the bar 32 of the sealing member 23. 25 The cam members 45 are rotated through a small angle about their axles 46 by the movement of a control rod 50. The elongate control rod 50 has two parts a first part 51 and a second part 52. The first part 51 (that, in the embodiment depicted in Figure 2, is a rod of rectangular cross-section, although such a 13 cross-sectional shape is not essential) has a number of pegs 53 extending from the vertical face of the first part 51 that is nearer to the back plate 21. The number of pegs 53 is equal to the number of cam members 45. Each peg 53 has a circular cross-section and is a close (but sliding and rotatable) fit 5 within a respective cylindrical cavity 49 of an associated cam member 45. Each cavity 49 extends horizontally from the first face 47 of the cam member 45. (The cavities 49 may extend through the cam members, thereby becoming, in effect, cylindrical apertures 49.) 10 When the control rod 50 is moved horizontally in the direction of the arrow A, the pegs 53 move each cam member 45, which rotates through a small angle. This rotation through a small angle causes a part of the cam members' edge surfaces 42 that are farther from the axles 46 (farther, that is, than the part of each cam member edge surface that is in contact with the is bar 32 when the door is open)is most distant from the axles 46 to come into contact with the top surface of the bar 32. For this to happen, the bar 32 has to move downwards. Such horizontal movement of the control rod 50 is effected when the free end 20 55 of the second part 52 of the control rod is moved. The second part 52 of the control rod, in the (preferred) embodiment illustrated in Figure 2, is a rod of circular cross-section that is threaded over at least the region adjacent to the free end thereof (that is, the end 55, that is remote from the first part 51 of the control rod). Conveniently, the second part 52 of the control rod is an 25 elongate stud (a stud usually being threaded over its entire length). The second part 52 of the control rod passes through the aperture 39 in the first arm 33 and its end 55 projects beyond the outer vertical surface of the arm 33. The aperture 39 is large enough, vertically, to enable the sealing member 23 to move between its highest and lowest levels without the arm 33 14 coming into contact with the second part 52 of the control rod 50. When the under-door seal is attached to the door 10 as shown in Figure 1, the free end 55 of the control rod 50 would contact the door frame 11 when the 5 door is nearly closed. Continuing the closing of the door 10 beyond this point, therefore, causes the control rod to be moved horizontally in the direction of the arrow A. When this occurs, the pegs 53, move the cam members about their axles, thus causing the sealing member 23 to be moved downwards. When the door 10 is completely closed, the gap under the door 10 10 is completely closed by the lower surface of the sealing member 23. The under-door seal shown in both Figure 1 and Figure 2 has a door frame contact member 25. The door frame contact member is screwed onto the free end 55 of the control rod. It may be a simple cap. The preferred door frame 15 contact member is shown in Figure 2. It is preferred because it is easily adjustable. It comprises an internally threaded ferrule 56 that is screwed onto the end 55 of the control rod the distance required to ensure that the under-door seal is applied when the door 10 is completely closed, and is then locked into place by a locking grub screw 57. 20 When the door 10 is opened after it has been closed, the sealing member 23 must be moved back to its "open door" position. Such movement is effected by two helical springs 60 and 61. The helical spring 60 has one end positioned over the pin 35 extending from the arm 33, and its other end 25 positioned over the pin 62 that extends, horizontally, in the elongate direction of the back plate 21, from a first block 64 that projects from the back plate towards the front plate 22. The helical spring 61 has one end positioned over the pin 36 extending from the arm 34, and its other end positioned over the pin 63 that extends, horizontally, in the elongate direction of the back plate 15 21, from a second block 65 that projects from the back plate towards the front plate 22. When the sealing member is at its highest level, the axes of the helical springs 60 and 61 are essentially horizontal. When the sealing member moves downwards, the pins 35 and 36 move downwards and the springs 60 5 and 61 become distorted, so that their axes are non-linear and are no longer horizontal. This distortion results in each spring applying an upward force to its associated pin 35, 36. This upward force is resisted by the cam members that are held stationary by their associated pegs 53 of the control rod. Once the door is opened, however, the control rod is free to move and the constraint 10 on the upwards force is no longer present. The pins 35 and 36, and thus the sealing member 23, are moved upwards, and the cam members are rotated back, until the sealing member reaches its highest level. The first block 64 has an aperture 66, similar to the aperture 39 in the first arm 15 of the sealing member, through which the second part 52 of the control rod 50 passes. In the embodiment illustrated by Figure 2, the back plate 21 has a recessed region 69 surrounding each axle 46, and part of each cam member 45 is 20 positioned within an associated recessed region 69. Engineers will appreciate that variations to and modifications of the illustrated embodiments described above may be used without departing from the present inventive concept, as defined by the following claims. For example, 25 each cam member shown in Figure 2 need not be generally oval in shape, but may be a circular disc with a camming surface extending from it.

Claims (7)

1. An under-door seal mechanism for attachment to a door, comprising: 1. a back plate adapted to be affixed to the lower region of said door and a front plate; said back plate and said front plate being horizontally elongate, the length of each plate in the horizontal direction being substantially equal to the width of said door; said front plate having horizontal apertures therein through which respective screws or bolts pass to be screwed into correspondingly located threaded horizontal cavities in said back plate;

2. a sealing member positioned between said front plate and said back plate; said sealing member comprising a horizontally elongate bar having a length substantially equal to the elongate length of said back plate and said front plate; the underside of said sealing member having a shape such that, when in contact with the surface underneath said door when said door is closed, forms a seal with said surface;

3. first and second arms extending upwardly above said bar, over respective end regions of said bar; each of said arms having a vertical slot therein to receive a respective post that extends horizontally from said back plate; each said post being a sliding fit within its associated slot; each of said arms also having a respective horizontal pin extending above said bar; said first arm having an aperture therethrough in the elongate direction of said bar;

4. at least one axle on said back plate extending horizontally towards said front plate, and a cam member mounted on said, or each, axle; said, or each, cam member comprising a disc having planar vertical faces separated by an edge surface, the lowermost part of which is in contact with the upper surface of said bar; said, or each, cam member having a 17 cylindrical cavity extending horizontally into the upper region of the cam member from the face thereof that is remote from said back plate;

5. an elongate control rod having a first part and a second part; said first part having at least one peg extending horizontally therefrom into, and being a sliding fit within, said cylindrical cavity in the upper region of the, or a respective, cam member; said second part comprising a rod that is an extension of said first part; said second part passing through said aperture in said first arm and having a short length thereof extending beyond the end of said sealing member;

6. first and second blocks projecting from said back plate towards said front plate; said first block having an aperture therein extending horizontally, parallel to the elongate direction of said back plate, in a position such that said aperture in said first block is aligned horizontally with said horizontal aperture in said first arm, so that said second part of said control rod passes through said aperture in said first block; a respective pin extending horizontally from each said block (a) in a direction towards an associated one of said pins extending from said arms above said bar, and (b) below the level of said aperture in said first block; and

7. first and second helical springs, the ends of said spring being positioned around respective first and second pins, each of said first pins being one of said pins extending horizontally from said first and second arms, and each of said second pins being one of said pins extending horizontally from said first and second blocks. 2. An under-door seal as defined in claim 1, including a door frame contacting member securely mounted on the end of the second part of said 18 control rod, that projects beyond the end of said sealing member. 3. An under-door seal as defined in claim 2, in which said second part of said control rod comprises a rod of circular cross-section that is threaded over at least a length of the end thereof that is remote from said first part of said control rod; and said door frame contacting member is an internally threaded ferrule that is screwed onto said second part of said control rod and is locked in its required position by an internal grub screw. 4. An under-door seal as defined in claim 1, claim 2, or claim 3, in which said back plate has a recessed region around said, or each, axle, within which part of the cam member mounted on the axle is positioned. 5. An under-door seal as defined in claim 1, substantially as hereinbefore described with reference to the accompanying drawings. Dated this eighteenth day of July, 2012, Trevor David Leisk By his Patent Attorneys DAVIES COLLISON CAVE