AP308A - A method and device for releasably securing a window in its closed condition. - Google Patents

Abstract

The invention provides a device 10 for releasably securing a window 20 in its closed condition by means of a rotatable leve arm 12.THe device 10 includes a cylindrical sleeve 16 which is connectable to the window 20 and provides a pivotal connection between the window and the lever arm 20.THe sleeve 16 defines a passage 36 and the lever arm 12 defines a complementary recess 34 for inserting a slidable bolt on a latch element 40 when the passage and recess arealinged with each other, thereby immobilising the lever arm. The latch element 40 is slidably displaceable out of the recess 34 by manipulating a key 64.

Description

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This invention relates to a method and device for releasably securing} a window in Its closed condition.

BACKGROUND TO THE INVENTION

Potential Intruders practise various methods of forcing open windows in order to gain access to dwellings, mainly for criminal purposes. Breaking a large window pane tends to attract the attention of neighbours and passers-by, and intruders accordingly prefer to break a smaller window pane adjacent to a window lever arm, allowing the window to be opened by simple manipulation of the lever arm thereby granting easy and unobtrusive access to the dwelling.

The present Invention seeks to provide a method and device for restraining unauthorised Intruders from manipulation of a window lever arm for the purposes of gaining access through the window.

SUMMARY OF THE INVENTION

According to the present invention there Is provided a method of releasably securing a window in its closed condition by means of a rotatable lever arm, by bringing the window Into its closed condition by rotating the lever arm to a position In which it engages a portion of an associated frame structure characterised by the step of aligning a first passage which Is defined by a cylindrical body about which the lever arm Is rotatable with a complementary recess defined by the lever arm before urging a bolt into the aligned passage and complementary

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recess In order to immobilise the lever arm, while allowing optional displacement of the, bolt from the complementary recess by means of a key co-operating with the bolt, whenever the lever arm Is to be released for rotation.

The bolt may be biased towards the complementary recess so that the bolt bears against an Inner surface of the lever arm whenever the passage and complementary recess are out of alignment, and the bolt is urged Into the complementary recess whenever the passage and recess are aligned with each other.

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The bolt is preferably displaced from the complementary recess by a camming C· action opposed to the bias on the bolt.

The invention extends to a device for releasably securing a window In Its dosed condition by means of a rotatable lever arm, which includes a body connectable to a portion of the window in order to provide a pivotal connection between the window and the lever arm whereby in use, the lever arm Is rotatable to a position In which it engages a portion of an associated frame structure, thereby bringing the window Into Its closed condition, characterised in that the body is cylindrical and defines a passage capable of being aligned with a complementary recess In the lever arm when the window is In. Its closed ' condition, permitting a displaceable bolt to be simultaneously locatable in the passage and the complementary recess when they are aligned with each other, thereby immobilising the window lever arm, while a lockable displacing means is further provided, co-operating with the bolt and operable by a key, to allow the bolt to be optionally withdrawn from the complementary recess to free the lever arm for rotation.

The body may be constituted by a cylindrical sleeve fitting with slight clearance Into a corresponding bore defined by the lever arm. In a preferred, embodiment of the Invention the sleeve accommodates the lockable displacing means while providing a passage, through its side, walls for displacing the bolt in transverse relationship to the rotational axis of the lever arm.

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The sleeve may further accommodate resilient biasing means for urging the bolt towards an inner surface defined by the lever arm when the passage in the body and the complementary recess in the lever arm are out of alignment with each other, and urging the bolt into the complementary recess whenever it is aligned with the passage.

The displacing means may include a camming portion co-operating with the bolt for displacing the bolt against the bias of the resilient biasing means.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described below with reference to the accompanying diagrammatic drawings in which

Figure 1 shows a partial view of a known window assembly having an ordinary lever arm for opening and closing the window;

Figure 2 shows a partial view of the window assembly of Figure 1 in which the conventional lever arm has been substituted by a device according to the invention;

Figure 3 shows a partial vertical sectional view along the pivotal axis of the device of Figure 2, on an enlarged scale;

Figure 4 shows a further partial vertical sectional view along the pivotal access of the device of Figure 2 illustrating its operative condition;

Figure 5 shows a similar view of the device shown in Figure 4 illustrating its inoperative condition;

Figure 6 shows an upper plan view of a camming disc forming part of the

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Figure 7 shows a perspective view of a latch element forming part of the device shown in Figure 3;

Figure 8 shows a side elevation of a sleeve forming part of the device shown in Figure 3;

Figure 9 shows an opposed side elevation of the sleeve shown in Figure 8; and

Figure 10 shows a side elevation of a lever arm forming part of the device shown in Figure 3.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

In the drawings reference numeral 10 generally denotes a device according to the invention. The device 10 includes a lever arm 12 defining a composite cylindrical bore 14 (Figure 10) of circular cross-section extending transversely in relation to the lever arm.

A cylindrical sleeve 16 of annular cross-section fits with clearance inside the portion of the bore 14 having the larger cross-sectional diameter. The diameter of the adjacent bore is smaller than that of the first-mentioned bore, and marginally larger than that of a pivot pin 18. This pin forms part of a movable window frame 20 in a known window assembly, generally denoted by reference numeral 22.

The sleeve 16 is blanked off at one end and defines a co-axial passage 24 of circular cross-section through which the shank of a threaded screw 26 is insertable. The pivot pin 18 has a co-axial blind passage 28 defining female thread formations, which are complementary with the thread of the screw 26. this thread conveniently corresponds to that of a conventional locking screw 30 (Figure 1) used in the window assembly 22 for securing an ordinary lever arm 32 to the pivot pin 18.

The lever arm 12 defines a rectangular recess 34 extending in perpendicular relationship to the bore 14 (Figure 3). The sleeve 16 defines a matching

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passage 36 (Figure 9) which is so arranged that when the device 10 is fully assembled, the edges of the recess 34 and the passage 36 are able to register with each other by rotation of the lever arm 12 about the pivot pin 18. The lever arm 12 and sleeve 16 are conveniently made of brass or a similar metal allowing these components to be cast or forged with relative ease. These are preferably heat-treated, or otherwise filled with wear-resistant linings, in order to maintain the inner dimensions of the recess 34 and passage 36 during use of the device 10, as described more fully below.

The sleeve 16 defines a further rectangular passage 38 extending through a portion of the sleeve opposed to the passage 36 and having its walls and edges parallel to those of the passage 36. The lower walls of the passages 36 and 38, being the walls closest the blanked-off end of the sleeve 16, are aligned with each other while the remaining walls of the passage are generally parallel to the corresponding walls of the passage 36.

A latch element 40 shown in figure 7a forms part of the device 10 and has a rectangular, slab-shaped body 42 defining an upper surface 44 and a lower surface 46. The lateral edges of the body 42 pass with clearance between the lateral edges of the passage 38 while the thickness of the body 42 is slightly less than the respective height of the recess 34 and the passage 36. A rectangular bolt 48 which is co-extensive with the slab-shaped body 42 has parallel lateral edges stepped inwardly and equidistant from the lateral edges of the body 42 so that the bolt is capable of passing with slight clearance through the passage 36 into the recess 34.

The latch element 40 further includes a raised formation 50 extending perpendicularly to the upper surface 44 and adjacent to the edge of the body 42 remote from the bolt 48. The raised formation 50 defines a camming surface 52 facing towards the bolt 48.

A rectangular thrust block 54 is integrally connected to the body 42 and projects perpendicularly from its lower surface 46. The thrust block 54 is located intermediate of the bolt 48 and the raised formation 50, and towards the latter.

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A helical spring 56 is secured to the thrust block 54 and projects substantially parallel to the lower surface 46 in the direction of the raised formation 50. The assembly of the device 10 is such that in use the unconnected end of the spring 56 bears against an inner recess 58 defined by the sleeve 16 (figure 3).

The latch element 40 is operable by means of a cam wheel 60 constituted by a metal disc defining a rectangular slot 62 extending radially from a region adjacent to the pivotal axis of the disc wheel towards its outer periphery (figure 6). The cam wheel 60 is operable by means of a key 64 which is insertable into a cylindrical body 66 arranged adjacent to the cam wheel, as described below.

A rectangular plate 68 is connected to the end of the cylindrical body 66 opposite to the end at which the key 64 is insertable, and projects in co-axial relationship to the cylindrical body. The cylindrical body 66 is rotatable about its longitudinal axis within a sleeve 70, which is secured within the cylindrical sleeve 16 by way of complementary thread formations extending from the open end of the sleeve 16. The body 66 and sleeve 70 are substantially similar in construction to corresponding components used in known locks installed on furniture for the purposes of locking cupboard doors and drawers of desks, for example.

The body 66 is held captive in the sleeve, firstly by an annular collar 72 projecting radially from the end of the body at which the key 64 is insertable, and secondly by the cam wheel 60, which is secured to the plate 68 by means of a locking pin 74. The cam wheel 60 partially projects beyond the periphery of the sleeve 70 irrespective of the position of the body 66 in relation to the sleeve.

The cylindrical body 66 defines four transverse passages for accommodating slidably displaceable tumblers 76. These tumblers are spring-loaded in order to urge them outwardly along the above-mentioned transverse passages so as to partially project from the lateral surface of the body 66.

The portions of the tumblers 76 projecting beyond the body 66 are capable of being seated in a longitudinal groove 78 defined by the sleeve 70, whenever the key 64 Is extracted from the cylindrical body 66. The body 66 accordingly becomes immobilized whenever the tumblers 76 register with the groove 78.

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The key 64 has a serrated edge 80 defining raised portions which co-operate with corresponding portions of the tumblers 76 when the key is fully inserted in the slot of the body 66. The tumblers 76 are thereby urged inwardly along their respective passages until they are fully retracted from the groove 78. This allows unrestricted rotation of the body 66 in relation to the sleeve 70.

Once the key 64 is fully inserted as shown in figure 3 and rotated about the longitudinal axis of the body 66, the co-rotating cam wheel 60 bears against the camming surface 52, thereby displacing the latch element 40 against the bias of the spring 56. On completion of rotation through approximately 180·,(as shown in figure 5) the bolt 48 is fully withdrawn from the recess 34 in the lever arm.

The lever arm 12 is free to be rotated about the pivot pin 18 whenever the bolt 48 is extracted from the recess 34. The window 20 may accordingly be opened once the key 64 has been operated in the manner described above. The leading edge of the bolt 48 is kept in sliding contact with the inner wall of the bore 14 in the lever arm 12, through the bias imparted by the spring 56 on the latch element 40. A friction washer 82 is preferably located between the lever arm 12 and the frame of the window 20 in order to ensure that the lever arm does not accidentally return to its initial position where the bolt 48 can be urged back into the recess 34 after the window has been opened.

The key 64 is conveniently extracted at any time after the lever arm 12 has been rotated sufficiently far in order to allow the window 20 to be opened. The structure of the body 66 is such that the key 64 can only be withdrawn when the tumblers 76 are re-aligned with the groove 78, thereby locking the body 66 to the sleeve 70 again. The cam wheel 60 is accordingly restored to its initial position shown in Figures 3 and 4. The leading surface of the bolt 48, however, continues to bear against the inner sidewalls of the bore 14. When the window 20 is to be locked again, it is drawn back towards its associated frame structure in the usual manner before the lever arm 12 is rotated, restoring it to the position shown in figure 2.

As soon as the bolt 48 comes into alignment with the passage 34 it is urged back into this passage under the influence of the spring 56. The lever arm 12 is

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accordingly again immobilized until the key 64 is re-inserted into the body in order to free the camming wheel 60 once more.

The applicant believes that the device 10 can be fitted to existing window assemblies with comparative ease after an existing lever arm 22 has been released by removal of its associated locking screw 30. The friction washer 82 and lever arm 12 are subsequently positioned on the pivot pin 18. The sleeve 16 is then positioned inside the passage 14 so that the recess 34 and passage 36 are aligned with each other when the lever arm 12 is set in the closed condition (figure 2). The sleeve 60 is then secured to the pivot pin 18 by means of the screw 26. A lubricating washer 84 is preferably positioned between the lever arm 12 and the sleeve 16 during installation. This washer 84 will tend to reduce the risk of displacement of the sleeve 16 in relation to the pivot pin 18 through operation of the lever arm 12. This ensures that the bolt 48 and passage 34 will consistently align with each other whenever the lever arm 12 is set in its closed condition.

The latch element 40 and its associated spring 56 are subsequently laterally insertable in the sleeve 16 through the passage 38. An alternative latch element 40’ shown in figure 7b has structural features 42’, 44’, 46’, 48’, 50’ and 52’ corresponding to the parts 42, 44, 46, 48, 50 and 52 of the latch element 40. The thrust block 54', however, is detachable from the body 42' as shown in figure 7b. During installation the thrust block 54* and its associated helical spring 56 inserted through the passage 38 and lowered into the inner space defined by the sleeve 16. The block ’54 and spring 56’ are finally positioned as illustrated in figure 2.

The remaining portion of the latch element 40’ is laterally insertable through the passage 38 and secured to the thrust block 54’ by means of a threaded screw 43 passing through a countersunk hole 45 extending through the body. The thread formations of the screw 43 engage complementary female thread formations defined by a passage 47 in the thrust block 54’, allowing the thrust block and body to be secured to each other by tightening the screw 43.

The locking assembly comprising the sleeve 70, cylindrical body 66 and cam wheel 16 are installed after the latch element 40 or 40’ as the case may be has

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been located in its usual operating position (Figure 3). This is done by allowing the male thread formations of the sleeve 70 to engage with complementary female formations inside the bore of the sleeve 16. The locking assembly may be finally secured by means of spot welding or a similar technique in order to avoid tampering with the device 10 aimed at defeating its effectiveness.

The applicant believes that the installed device 10 will serve to counteract previous methods of gaining unauthorised access to domestic dwellings, for example.

The inventor foresees that an attempt may be made to defeat the device 10 by applying an extension piece to the lever arm 12 in order to overcome the restraining force of the bolt 48 in the recess 34. This is conveniently counteracted, however, by providing a region of weakness along the lever arm 12 whereby the lever arm itself is severed before the latch element 40 or its associated components are damaged.

The invention lends itself to a variety of adaptations and modifications without departing from the essential elements of the invention, defined in its most general terms. The scope of the invention should accordingly not be construed

Claims (8)

1. A method of releasably securing a window in Its closed condition by means of a rotatable lever arm, by bringing the window into its closed condition by rotating the lever arm to a position in which It engages a portion of an associated frame structure characterised by the step of aligning a first passage which Is defined by a cylindrical body about which the lever arm Is rotatable Is aligned with a complementary recess defined by the lever arm before urging a bolt Into the aligned passage and complementary recess In order to immobilise the lever arm, while allowing optional displacement of the bolt from the complementary recess by means of a key co-operating with the bolt, whenever the lever arm Is to be released for rotation.

2. A method according to claim 1 In which the bolt Is biased towards the complementary recess so that the bolt bears against an inner surface of the lever arm whenever the passage and complementary recess are out of alignment, and the bolt is urged into the complementary recess whenever the passage and recess are aligned with each other.

3. A method according to claim 2 In which the bolt is displaced from the complementary recess by a camming action opposed to the bias on the bolt.

4. A device for releasably securing a window In Its closed condition by means of a rotatable lever arm, which Includes a body connectable to a portion of the window in order to provide a pivotal connection, between the window and the lever arm whereby in use, the lever arm is rotatable to a position In which It engages a , portion of an associated frame structure, thereby bringing the window into its closed condition, characterised In that the body is cylindrical and defines a passage capable of being aligned with a complementary recess In the lever arm when the window is In Its closed condition, permitting a displaceable bolt to be simultaneously locatable in

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the passage and the complementary recess when they are aligned with each other, thereby immobilising the window lever arm, while a lockable displacing means is further provided, co-operating with the bolt and operable by a key, to allow the bolt to be optionally withdrawn from the complementary recess to free the lever arm for rotation.

5. A device according to claim 4 In which the body is constituted by a cylindrical sleeve fitting with slight clearance Into a corresponding bore defined by the lever arm.

6. A device according to claim 5 in which the bolt Is displaceable in transverse relationship to the rotational axis of the lever arm.

7. A device according to claim 6 which further includes resilient biasing means for urging the displaceable bolt towards an inner surface defined by the lever arm when the passage, in the body and the complementary recess In the lever arm are out of alignment with each other, and urging the bolt Into the complementary recess whenever it Is aligned with the passage.

8. A device according to claim 7 In which the displacing means Includes a camming portion co-operating with the bolt for displacing the bolt against the bias of the resilient biasing means.