GB2264324A

GB2264324A - Window-breaking device

Info

Publication number: GB2264324A
Application number: GB9203905A
Authority: GB
Inventors: Jeremy Frank Ellis
Original assignee: ZEDBEND Ltd
Current assignee: ZEDBEND Ltd
Priority date: 1992-02-19
Filing date: 1992-02-19
Publication date: 1993-08-25
Also published as: GB9203905D0

Abstract

A device for use in breaking a window comprises a body (1) carrying a movable plunger (2) with a point at one end, and means (4) for driving the plunger relative to the body, and mounting means for mounting the body on a window frame with the point directed towards the window (12) such that the point can be driven into the window to fracture the window. <IMAGE>

Description

WINDOW-BREAKING DEVICE This invention relates to a device for use in breaking a double-glazed window in an emergency.

The use of double-glazed windows is becoming more widespread as the cost advantages of effective thermal insulation in buildings are more widely appreciated.

However, a danger with such windows of the fixed, rather than opening, type is also becoming apparent. In the event of a fire in a building with such windows, escape through windows is hindered or prevented because the air or gas trapped between the sheets of glass, especially in sealed glazing units, cushions any direct blow to one of the sheets and protects the glass from breaking. While this might be advantageous with an accidental blow, in an emergency an inability to break the window could have very serious consequences.

The emergency services have recognised this problem and have found that the use of a sharp punch driven into the window by a hammer will fracture one sheet of the glass such that the window may then more readily be broken. However, it is not practical to provide a hammer and punch at each window in a building; the cost would be excessive and the probability of the hammer and punch being inadvertently or deliberately removed, and therefore not being available when needed, is high.

Accordingly, one aspect of the present invention provides a device for use in breaking a window, comprising a body carrying a movable plunger with a point at one end, and means for driving the plunger relative to the body, and mounting means for mounting the body on a window frame with the point directed towards the window such that the point can be driven into the window to fracture the window.

One embodiment of the invention comprises a slidable plunger having a point at one end and a knob at the other end, such that a blow struck to the knob can drive the point into the window to fracture the window.

Preferably, the plunger is spring-biased away from the window to ensure that the plunger moves through a full stroke when struck. The withdrawal of the point under the influence of the spring after striking the window has also been found advantageous in fracturing the glass. The device is preferably arranged so that, at rest, the point is spaced from the window surface by 10-25 mm. Too great or too small a distance may lessen the effectiveness of the blow. The use of a spring also reduces the risk of an inadvertent blow to the knob causing fracture of the glass.

The knob is preferably large enough to permit it to be struck comfortably by the palm of the hand with sufficient force to drive the point of the plunger into the glass. The point is preferably hardened to penetrate the glass sat isfactilv.

In a second embodiment of the invention, the plunger has a spring which can be tensioned to drive the point into the window. A knob on the free end of the plunger is pulled away from the body to tension the spring therein and locking means are provided to hold the plunger in this position until released in an emergency. The locking means may comprise a pin extending laterally from the plunger shaft and corresponding slots in the end of the body, through which the pin can pass when correctly aligned.

In a third embodiment of the invention, a lever is provided to urge the plunger into the glass, while in a fourth embodiment, the plunger is screw-threaded in the body so as to be driven into the glass by a screwing action.

The mounting means may comprise a bracket attachable across a corner of a window, preferably so as to locate the body at 50-100 mm from each edge of the window at the corner thereof. The bracket is suitably arranged to be attachable to the window frame by screws, thus permitting the device to be installed by unskilled labour, for example the house-owner. A range of different shapes and sizes of bracket may be provided to be selected according to the design of the window. The device is conveniently installed at a bottom corner of a window, for example the right-hand corner. The device can be readily re-used after a broken window is replaced, or can be removed for use on another window.

Another aspect of the invention provides a glazing unit comprising first and second glass sheets spaced apart and sealed together at the edges thereof, an air inlet to the space between the sheets and releasable sealing means for the air inlet.

Reference is made to the drawings, in which: Figure 1 is a perspective view of a device according to one exemplary embodiment of the invention; Figure 2 is a sectional view of the device shown in Figure 1; Figure 3 is a sectional elevation of an alternative construction to that shown in Figure 2; Figure 4 is a sectional elevation of a device according to the second embodiment of the invention; Figure 5 is a sectional elevation of a device according to the third embodiment of the invention; Figure 6 is a sectional elevation of a device according to the fourth embodiment of the invention; and Figure 7 is a section through a glazing unit according to another aspect of the invention.

Referring to Figures 1 and 2, the device comprises a tubular body 1 receiving therein a plunger 2 having a sharp pointed rod 3, suitably of hardened steel, at one end thereof, and a flat knob 4, for example of a plastics material, at the opposite end. The knob 4 is mounted on a shaft 5 which ends at a section 6 of greater diameter providing a shoulder on either side, the rod 3 extending therefrom.

The tubular body 1 is welded to a bracket 7 which is provided with a hole through which the rod 3 passes. A threaded sleeve 8 is screwed into the free end of the body 1 and engages the section 6 to return the plunger 2 in the body. A helical compression spring 9 extends between the section 6 and the bracket 7 to bias the section 6 against the sleeve 8.

Referring particularly to Figure 1, the bracket 7 is formed of steel and has at each end a portion 10 perpendicular to the plane of the bracket and provided with fixing holes by which the bracket may be screwed to a window frame 11.

In the case of a metal window frame self-tapping screws may be used. The configuration of the bracket is such that accurate positioning of the device relative to the glass 12 may readily be achieved in installation.

In use, a sharp blow to the knob with the palm of one hand will suffice to fracture the glass and release the seal between the two panes of the window. The window can then be broken and removed as with a single-glazed window.

Referring now to Figure 3, a modified construction for the device shown in Figure 2 is illustrated. The body 30 is in the form of a cylinder closed at one end but with a bore 31 therethrough through which the plunger 32 passe#s.

The other end of the body 30 is internally screw-threaded and fixing to the bracket 7 is carried out by drilling therethrough a hole of a diameter equivalent to the internal diameter of the body 30. A threaded plug 33 then extends through the hole in the bracket 7 to be engaged on the internal thread of the body 30. The plug 33 has an aperture therethrough through which the point 34 of the plunger passes. A helical compression spring 35 extends between a shoulder 36 on the plunger and the internal face of the plug 33. The knob 37 is screw-threaded onto the end of the plunger 32 and, as with the device illustrated in Figure 2, is struck a sharp blow, for example with the palm of the hand, to drive the point into the window.

Figure 4 shows an alternative arrangement, in which the body 40 is again essentially a cylinder closed at one end, but with a hole 41 therethrough through which the plunger 42 extends. A helical spring 43 extends between the closed end of the cylinder and a shoulder member 44 on the plunger, the spring being tensioned by pulling the knob 45 outwardly from the body. The plunger is locked in a position with the spring 43 under compression by means of a locking pin 46 through the plunger 42 which can pass through a slot in the end of the body 40, rotation of the knob 45, and therefore the plunger 42, serving to seat the pin against the external face of the end of the body 40.

To release the plunger so that the spring 43 can drive the point 47 thereon into the window glass, the knob 45 is rotated to bring the pin 46 into alignment with the slot and is then released.

The device shown in Figure 5 comprises a cylindrical body 50 closed at one end by a solid portion 51 containing a vertical slot therethrough in which a lever 52 is pivotally mounted. The lever consists of a disc 53 eccentrically mounted on a pivot 54 and with an arm 55 extending therefrom.

Rotation of the disc 53 under the influence of the arm 55 causes it to engage and drive the plunger 56 against the tension of a return spring 57. A pin 58 is also passed through the disc and engages the end face of the body 50 to prevent inadvertent rotation of the lever. The pin is retained by a chain 59 and can be readily withdrawn when the device is to be used.

In the device shown in Figure 6, the plunger 60 is screw-threaded in a plug 61 which is turn screw-threaded into the end of the cylindrical body 62. A helical compression spring 63 extends between the closed end of the body 62 and a shoulder 64 on the plunger 60. A knob 65 is secured to the end of the plunger and rotation of this knob causes the point 66 to be driven into the glass, the spring 63 assisting.

While reference has been made throughout to double-glazing, it will be appreciated that the invention is applicable to glazing units incorporating more than two panes of glass, if necessary the stroke of the plunger being extended to permit re-use of the device, after the first pane has been broken, to fracture the next pane.

In the arrangement illustrated in Figure 7, a sealed double-glazed unit comprises first 70 and second 71 sheets of glass spaced apart and sealed around their edges in conventional manner. The sealing arrangement is not illustrated. It has been found that, by releasing the seal between the two sheets, the glass may more readily be broken, and for this purpose, a small hole is drilled the first sheet 70 and a flexible plug 72 is inserted into the hole.

The plug 72 has a passage 73 therethrough which can be closed by a ribbed stopper 74 attached to the plug 72 by a flexible strap 75. The plug 72 is shaped with a circumferential groove 76 to receive the glass around the hole in the sheet 70 and is formed of a material sufficiently flexible to permit distortion of the plug during insertion whilst also providing an adequate airtight seal around the glass.

With the stopper 74 inserted, the glazing unit performs as a conventional sealed unit. In an emergency, the plug is removed and the first sheet can then be broken readily by striking it with a suitable hard object. The second sheet 71 can then be broken to permit escape through the window. It will be appreciated that existing glazing units may be readily adapted by drilling a hole and insertion of the plug, as well as the fitting of the plug during manufacture of the glazing unit. In place of the flexible body for installation before assembly of the sealed glazed unit, a two-part screw-threaded device may alternatively be used.

Claims

1. A device for use in breaking a window, comprising a body carrying a movable plunger with a point at one end, and means for driving the plunger relative to the body, and mounting means for mounting the body on a window frame with the point directed towards the window such that the point can be driven into the window to fracture the window.

2. A device according to Claim 1, comprising a slidable plunger having a point at one end and a knob at the other end, such that a blow struck to the knob can drive the point into the window to fracture the window.

3. A device according to Claim 1 or 2, wherein the plunger is spring-biased away from the window to ensure that the plunger moves through a full stroke when struck.

4. A device according to Claim 1, 2 or 3, wherein the mounting means are arranged so that, at rest, the point is spaced from the window surface by 10-25 mm.

5. A device according to Claim 2, wherein the knob is large enough to permit it to be struck comfortably by the palm of the hand with sufficient force to drive the point of the plunger into the glass.

6. A device for use in breaking a window, substantially as described with reference to, or as shown in, the drawings.

6. A device according to any preceding claim, wherein the point is hardened.

7. A device according to Claim 1, wherein the plunger has a spring which can be tensioned to drive the point into the window.

8. A device according to Claim 7, comprising a knob on the free end of the plunger which can be pulled away from the bódy to tension the spring therein, and locking means to hold the plunger in this position until released in an emergency.

9. A device according to Claim 8, wherein the locking means comprise a pin extending laterally from the plunger shaft and corresponding slots in the end of the body, through which the pin can pass when correctly aligned.

10. A device according to Claim 1, comprising a lever to urge the plunger into the glass.

11. A device according to Claim 1, wherein a plunger is screw-threaded in the body so as to be driven into the glass by a screwing action.

12. A device according to any preceding claim, wherein the mounting means comprises a bracket attachable across a corner of a window.

13. A glazing unit comprising first and second glass sheets spaced apart and sealed together at the edges thereof, an air inlet to the space between the sheets and releasable sealing means for the air inlet.

14. A device for use in breaking a window, substantially as described with reference to, or as shown in, the drawings.

Amendments to the claims have been filed as follows

1. A device for use in breaking a window, comprising a body carrying a slidable plunger having a point at one end and a knob at the other end, such that a blow struck to the knob can drive the point into the window to fracture the window, the plunger being spring-biased away from the window to ensure that the plunger moves through a full stroke when struck, and mounting means for mounting the body on a window frame with the point directed towards, but spaced from, the window such that the point can be driven into the window to fracture the window.

2. A device according to Claim 1, wherein the mounting means are arranged so that, at rest, the point is spaced from the window surface by 10-25 mm.

3. A device according to Claim 1 or 2, wherein the knob is large enough to permit it to be struck comfortably by the palm of the hand with sufficient force to drive the point of the plunger into the glass.

4. A device according to any preceding claim, wherein the point is hardened.

5. A device according to any preceding claim, wherein the mounting means comprises a bracket attachable across a corner of a window.