CA2159669A1

CA2159669A1 - Door security device

Info

Publication number: CA2159669A1
Application number: CA002159669A
Authority: CA
Inventors: Branko Naumovski
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-10-02
Filing date: 1995-10-02
Publication date: 1997-04-03

Abstract

The device is used for security by e.g the occupier of a hotel room. A toggle-type self-gripping mechanism is provided with thin jaw-blades. The blades are entered into the slot or gap between a door and a door jamb. The jaws engage the door-bolt, and the device enables a heavy gripping clamp to be applied to the bolt. The thin jaws do not buckle under the heavy clamping because they are constrained against buckling by the slot. A srew-clamp may be substituted for the toggle-clamp.

Description

.i 1 Title: DOOR SECURITY DEVICE

3 This invention relates to a device for improving the security with which doors4 can be locked against unauthorized entry.

8 The device is intended for use particularly by persons staying in hotel rooms,9 or the like, where the possible danger arises that a thief may try to force the 10 door, or a person with a pass-key to the door may try to obtain unauthorized 1 1 entry.

13 The device is applied by the occupier of a room, from the inside. The device 14 is used in conjunction with a pre-existing door bolt. The bolt may be of the 15 type that is manually applied, and is separate from the key-operated lock of 16 the door, or the device may be used in conjunction with a bolt ~csoci~ted 17 directly with a key-operated lock. The device may also be used on latch-bolts18 found in wedge/spring type latch mechanisms.

22 The invention lies in a door-bolt security device, which is based on the familiar 23 and conventional toggle-type self-gripping mechanism. The device comprises 24 a main lever, a handle, and a toggle strut, arranged in the usual way in such25 devices.

27 In the invention, the device includes jaw-blades, which are of hard, thin, sheet 28 steel. The sheet steel is thin enough to fit into the kind of gap or slot 29 obtaining between a door and a door jamb.
31 The two jaw-blades are flat, and are co-planar, and the two jaw-blades lie in a plane perpendicular to the axis of the main pivot of the device, ie the pivot of2 the main lever to the handle.

4 The thin jaw-blades are arranged to be passed into the slot between a door 5 and its door jamb. In that slot, the jaw-blades are arranged to clamp around 6 the door-bolt. A heavy gripping clamp force can be built up between the jaws, 7 but the jaw-blades do not buckle because the blades are supported and 8 constrained between the door and the door jamb.

12 There are many known devices which are based on the operation of the 13 toggle-type self-gripping mechanism. Typical of these is that shown in US-14 3,184,838 (Johnson, 1965). The device of the present invention is 15 distinguished from such previous proposals by the structure and arrangement 16 of the jaws, as arranged for the purposes described herein. Of interesl also is 17 US-4,136,589 (Kerr, 1979) in which the self-gripping mechanism is used to18 hold a (door-)key.

22 By way of further explanation of the invention, exemplary embodiments of the 23 invention will now be described with re~re~ce to the accompanying drawings, 24 in which:
26 Fig 1 is a pictorial view of a door-bolt gripping security device that embodies 27 the invention;
28 Fig 2 is a side elevation of a door and door jamb combination, to which the 29 device of Fig 1 has been applied;
30 Fig 3 is a front elevation of the combination of Fig 2;
31 Fig 4 is a view of a device similar to that shown in Fig 1;

`

Figs 5A and 5B show the device of Fig 4 is cli~ere, IL operative configurations;2 Fig 6 is a side view of the device of Fig 4;
3 Fig 7 is a pictorial view of another device which embodies the invention;
4 Fig 8 is a plan view of the device of Fig 7;
5 Fig 9 is a cross-section on line 9-9 of Fig 8;
6 Fig 10 is a front elevation of the device of Fig 7;
7 Fig 11 is a view of one of the components of the device of Fig 7;
8 Fig 12 is a view of another component of the device of Fig 7.

The apparatuses shown in the accompanying drawings and described below 11 are examples which embody the invention. It should be noted that the scope 12 of the invention is defined by the accompanying claims, and not necess~rily 13 by specific features of exemplary embodiments.

The device 20 shown in Fig 1 is based on a conventional self-gripping 16 mechanism, which may be described briefly as follows. A main lever 23 and a 17 handle 25 are arranged for squeezing together. The main lever is pivoted at 18 27 to a jaw-lever 29, which is in turn pivoted, at 30, to the handle 25. A strut 19 32 is pivoted at 34 to the lever 23, and the strut 34 abuts, at its other end 36, against an adjustable screw 38 in the handle 25. Jaw-bases 39,40 are formed 21 integrally one to the handle 25, and the other as a compone t of the j~w lovcr 22 29.

24 Jaw-blades 43,45 are attached to the jaw-bases 39,40 by means of rivets 47.
26 The geometry of the self-gripping mechanism is such that when the handle 25 27 and main lever 23 are squeezed together, the pivot 27, the pivot 34, and the 28 abutment at 36, become aligned in a straight line. The jaw-blades 43,45 lie at 29 a specific distance apart when this straight-line condition is reached. The person using the device adjusts the screw 38 until the distance apart of the 31 jaw-blades at the straight-line condition is a little less than the width of the item being gripped between the jaw-blades.

3 The strut 32, when nearing the straight-line condition, is acting as a toggle arm 4 approaching its dead-centre. As such, the mechanical advantage of the handle-to-lever (23-25) force as against the jaw-tojaw (43-45) force, becomes 6 very high, as the straight-line condition is approached and reached. The 7 conventional self-gripping mechanism owes its wide acce~lability and usage to 8 the fact that not only can a person leave the tool with the gripping force 9 retained therein, but, because of the high mechanical advantage, the person needs only a small effort to achieve a very high jaw-tojaw gripping force.

12 It is recognised that these are the very qualities required in the device having 13 the function as described herein.

In the present case, the device is required to grip a door-bolt so tightly that a 16 thief trying to force the door from outside cannot move the bolt. A
17 considerable gripping force is required to achieve this end. Of course, in the 18 present device, the ability for the device to retain the gripping force, when 19 released, also is essential.
21 It is noted that the jaw-tojaw gripping force that can be achieved by a person 22 having a reasonable strength of the hands, is of the same order of magnitude 23 as the jaw-tojaw gripping force on a door bolt which is needed to ensure a 24 good level of security, ie to prevent the door-bolt from being forced.
26 The jaw-blades 43,45 are of sheet metal (steel), having a thickness of about 27 1.5 mm. Ordinarily, it is not possible for such thin jaw-blades to exert a 28 gripping force of the magnitude required, bec~ se thin jaw-blades simply 29 buckle and bend aside at much smaller forces than that. A thin jaw-blade can only exert forces at that level if it is supported or confined against buckling.31 ,., It is recognised that in use of the present device the jaw blades are in fact

2 confined and constrained against buckling, even at high gripping forces, by

3 the fact that the jaw-blades, when in use, lie in the narrow gap or slot between

4 the door and the door jamb. The narrow slot between the door and the doorjamb provides the constraint which confines the jaw-blade against buckling. If 6 the slot were substantially wider than the jaw-blade, the blade would be 7 permitted to buckle within the space allowed.
9 The thickness of the blade material should be a little less than the width of the slot. Of course, the width of the slot varies with di~erenl door inslallations; it 11 has been found that a blade thickness of about 1.5 mm is able to fit into the 12 slots as encountered in real doors, in nearly every case. As mentioned, the 13 thickness of the jaw-blade as dictated by the width of the slot ordinarily found 14 in doors, provides an adequate strength of blade to grip the bolt, given that the blade is supported by the slot.

17 In fact, the user should take care not to apply full force to the jaw-blades when 18 the blades are outside the slot, since then there would be a real chance the 19 jaw-blades might buckle.
21 A blade thickness of more than about 2 mm means that the device can only 22 be used in those cases where the slot between the door and the door jamb is 23 unusually wide. A blade thickness of less than about 1 mm means that the 24 blade is too flimsy to exert a large enough force on the door-bolt, even though the jaw blade is confined against buckling within the slot.

27 Fig 2 shows a side elevation of a door jamb 49, to which is attached the usual 28 door-abutment-strip 50. The door 52 opens inwards, ie to the right in Fig 2, 29 and the abutment strip 50 defines the limit-stop against which the door moves upon closing. Upon the door being closed against the abutment strip, the 31 door-bolt 54 enters a complementary bolt-hole (not shown) in the door jamb _ 6 49. The door-bolt 54 may be advanced into the bolt-hole by the turning of a 2 key in a lock, or by manual manipulation of the bolt, or by wedge/spring latch3 action, as deler~ ed in the case of the particular door.

Door-bolts vary as to size and cross-sectional shape. However, it has been 6 found that the size and shape of cut-out openings 56 in the jaw-blades 43,45 7 as shown will serve for most types of door-bolt. The length 58 of the rounded 8 cut-out should be about 15 mm, and the depth 60 also about 15 mm. There 9 should be 3 or 4 cm of free blade (distance 63) between the cut-out 56 and the thicker jaw-bases 39,40, to allow the jaw-blades to be inserted far enough 11 into the slot 65 between the door 52 and the door jamb 49 (Fig 3) to be sure 12 of clamping around the bolt 54. The jaw-blades 43,45 should protrude (at 67) 13 no more than about 5 mm beyond the cut-out 56.

The material of the jaw-blades should be of hard steel, heat-treated for 16 strength. It is preferred that the jaw-blades should be hard enough to dig in 17 (slightly) into the material of the door-bolt: often, though, door-bolts are 18 themselves made of hard steel.

The material of the jaw blade pre~erably is hard enough that a corner of the 21 jaw blade can serve as a screw driver, and also so that a sharpened edge, as 22 at 69 in Fig 4, can serve as a cutter. Another cut-out 70 in the jaw-blades, 23 positioned in the unused space inside the bolt cut-out, can serve as a wire 24 stripper, or as general (light duty) pliers.
26 Because the thin sheet metal of the jaw-blades is supported against buckling 27 by being inserted in the slot 65, it is worthwhile to add a good depth of metal 28 in the plane of the jaws. (Such depth of metal could not be taken advantage 29 of if the jaw-blade were not supported against buckling.) The jaw-blade should be at least 1 cm deep (pre~eral,ly 1.5 cm) outside the cut-out 56 at 72, 31 and 3 cm deep (pre~erably 4 cm) near the base, at 74.

~_ 7 2 The device as described is portable and light in weight. The device can easily3 fit into a person's luggage or briefcase, or even into a lady's handbag. The 4 security provided by the device amply compensates for any minor

5 inconvenience of carrying the device.

7 The device is inexpensive, and may be adjusted, in use, to suit a wide variety8 of sizes and types of door-bolt (although door-bolts really do not differ very9 much as to size and shape). The device, under the right conditions, and 10 having been installed properly, gives extremely good security against 11 unauthorised entry.

13 It will be noted that, with the use of the device, entry is denied even to 14 persons equipped with a duplicate key or a master-key. Even though the regular opening mechanism of the door is totally disabled by the device, the 16 performance of the regular mechanism is not impeded or i"lel~ered with, and 17 is left just as it was upon removal of the device.

19 In the case where a room door is not fitted with a sliding-bolt, the device can be applied to the common wedge/spring latch bolt; very few doors, at least 21 doors of the type likely to be encounlered in a room in which a person might 22 want to be secure, would lack a bolt of some kind, to which the device may 23 be applied.

Figs 7,8,9,10 show a further embodiment of the invention. Flat thin jaw-blades 26 80L,80R are present, as previously described. The jaw-blades are made of27 metal, pr~erably a hard stainless steel.

29 The left jaw-blade 80L is clamped and mounted between plastic mouldings,being a top moulding 82LT and a bottom moulding 82LB. The bottom 31 moulding is formed with pegs 83, which are sized to be a tight inle~rere"ce fit inside corresponding bosses 84 in the top moulding 82LT. The jaw-blade 80L
2 is formed with holes, whereby the jaw-blade fits over the pegs.

4 The top and bottom mouldings 82LT,82B are engaged together, and the fit of 5 the pegs 83 in the bosses 84 is tight enough, when the mouldings are

6 pressed together, to keep the mouldings assembled and locked together, with

7 the jaw blade 80L held therebetween.
9 The same description applies to the right jaw blade 80R and the respective 10 top and bottom mouldings 82RT,82RB.
11 .
12 The plastic mouldings extend rearwards, and are brought together to form a 13 pivot point 86. As shown in Fig 9, the four mouldings lie in a stack at the 14 pivot point 85, whereby pivoting motion can take place between the left mouldings 82LT,82LB and the right mouldings 82RT,82RB.

17 The device includes a slit bolt 86, which is shown in Fig 11. The slit 87 in the 18 bolt 86 is wide enough to accommodate the thickness of the jaw-blade. The 19 bolt 86 is attached to the left jaw-blade 80L by means of a riveted through-pin 20 89, which permits the bolt to pivot with respect to the jaw-blade. The slit 87 is 21 long enough to extend over both jaw-blades, and to permit opening and 22 closing movements of the jaw-blades.

24 Fig 12 shows a spring leaf 90, which is arranged to resiliently urge the jaw-25 blades apart.

27 The two right mouldings 82RT,82RB, when pressed together, form a cylindrical 28 abutment 92. A hand-nut 93 is threaded to the non-slit end 94 of the slit bolt 29 86. When tightened, the hand-nut lies against the abutment 92.
31 In operation, a person applies the jaw-blades into the gap between the door and the door jamb, as previously described. The jaw-blades are tightened 2 down onto the door-bolt by tightening the hand-nut 93.

4 It will be understood that the form of the slit bolt 86, in which the jaw-blades 5 lie in the slit, is such as to maintain the two jaw-blades flat and co-planar. As 6 previously described, the door jamb gap serves to resist buckling of the thin 7 jaw-blades as a heavy clamp is applied: the slit bolt 86 similarly also serves,

8 by its shape, to resist buckling of the jaw-blades.

10 It will be understood also that the components of the device are held together, 11 and maintained in alignment, by the use of just one riveted pin 89. The rest of 12 the connections are made simply by pressing the plastic mouldings together.

14 The device is light enough to be carried in a hand bag or the like, and yet the 15 device is strong enough that a heavy clamp force can be applied to the door-1 6 bolt.

Claims

CLAIM 1. Door-bolt security device, in which:
the device includes jaws, comprising respective jaw-blades, which are of hard, thin, sheet steel;
the sheet-steel jaw-blades are flat, co-planar, and thin enough to fit into the kind of gap or slot that is typical between a closed door and a corresponding door jamb;
the sheet-steel jaw-blades are so shaped and adapted as to be suitable for operative gripping engagement with the bolt of a door;
the device includes a manually-operable means for pressing the jaws together onto the door-bolt with sufficient force that the jaw-blades grip the door-bolt forcefully enough to hold the bolt against unauthorized movement of the door-bolt;
the device includes a means for holding and retaining the jaw-blades gripped to the door-bolt with the said sufficient force, even when the manually-operable means is released;
and in relation to the thickness of the sheet steel, the planar extent, size, and shape, of the sheet-steel jaw-blades is such that:
(a) if the said sufficient force between the jaw-blades and the door-bolt were to be applied when the jaw-blades are outside the gap, and unconstrained thereby, the jaw-blades would then buckle out of the flat and planar form thereof; and (b) if the said sufficient force between the jaw-blades and the door-bolt is applied when the jaw-blades are placed within the gap, the jaw-blades are then constrained by their fit within the gap against the said buckling.
CLAIM 2. Device of claim 1, wherein:
the means for holding and retaining the jaw-blades comprises a main lever, a handle, and a strut, arranged in a toggle-type self-gripping operative relationship;

the jaws are disposed respectively on the lever and on the handle;
the device includes a main pivot, having a main pivot axis, at which the main lever is pivoted to the handle;
the two jaw-blades are co-planar, and lie in a plane perpendicular to the axis of the main pivot.
CLAIM 3. Device of claim 1, wherein the jaw-blades are between 1 mm and 2 mm thick.
CLAIM 4. Device of claim 3, wherein the jaw-blades are about 1.5 mm thick.
CLAIM 5. Device of claim 1, wherein the jaws include jaw-bases, and the jaw-blades are riveted to the jaw-bases.
CLAIM 6. Device of claim 1, wherein the jaw-blades are provided with cut-outs which are suitable for engagement with the door-bolt.
CLAIM 7. Device of claim 6, wherein the cut-outs in the jaw-blades form a rounded cavity about 1.5 cm long and about 1.5 cm deep.
CLAIM 8. Device of claim 6, wherein the jaw-blades are formed with a substantial depth of metal outside the cut-outs.
CLAIM 9. Device of claim 8, wherein the said depth is at least 1 cm.
CLAIM 10. Device of claim 1, wherein the jaw-blades are formed with a substantial depth of metal at the jaw-base.
CLAIM 11. Device of claim 10, wherein the said depth is at least 3 cm.
CLAIM 12. Device of claim 1, wherein, in respect of each jaw-blade, the depth of the jaw-blade, being the dimension measured in the plane of the sheet metal of the jaw-blade along the line of action of the said force on the door-bolt, is at least 1 cm.
CLAIM 13. Door-bolt security device, in combination with a door and a corresponding door-jamb in relation to which the door is closed and bolted, wherein:
the device includes a pair of jaws, which lie in operative gripping engagement with a bolt of the door;
the jaws include respective jaw-blades, which are of hard, thin, sheet steel;
the sheet-steel jaw-blades occupy the gap or slot between the closed door and the door jamb;
the device includes a manually-operable means for pressing the jaws together onto the door-bolt with sufficient force that the jaw-blades grip the door-bolt forcefully enough to hold the door-bolt against unauthorized movement of the door-bolt;
the device includes a means for holding and retaining the jaw-blades gripped to the door-bolt with the said sufficient force, even when the manually-operable means is released;
the sheet-steel jaw-blades are substantially flat and planar;
the sheet-steel jaw-blades are dimensionally large in the plane of the blade;
and the fit of the sheet-steel jaw-blades in the said gap or slot is tight enough that the jaw-blades are constrained thereby against gripping-force-induced buckling of the sheet metal.