GB2089417A - Lock keys - Google Patents

Abstract

A lock of the type having a double bit key wherein the shape of the keyhole, and that of the corresponding key comprise a central circular core (2), a first bit (3) extending tangentially to the core, and a second bit (4) also extending tangentially to the core and which is directed generally away from the first bit (3), the two bits (3, 4) subtending an angle of other than 180 DEG with one another. <IMAGE>

Description

SPECIFICATION Improved safety lock The present invention relates to an improved safety lock. More particularly, the present invention relates to locks of the multiple bolt type.

In known double-bit lock mechanisms, the key comprises a first bit which is radial to the shaft of the key and a second bit which is tangential to the shaft. The narrowing of both parts which is necessary to produce a radial bit results, however, in a detrimental weakening of the key. The lock mechanism must, of course, have a construction complementary with that of the key. Lock mechanisms are also known which utilise keeps having two bits which are both tangential to the shaft. These bits are distinguished from one another by a difference in thickness, but this can result in incorrect insertion of the key into the lock if, as is desirable, there is considerable play in the shaft when the key is inserted into the lock.

According to the present invention there is provided a safety lock of the type having a double bit key wherein the shape of the keyhole, and that of the corresponding key, comprises a central circular core (2), a first bit (3) extending tangentially to the core, and a second bit (4) extending tangentially to the core and which is directed generally away from the first bit (3), the two bits (3, 4) subtending an angle of other than 1 800 with one another. Such an arrangement means that correct insertion of the key can be safely ensured whilst maintaining the strength of the key, even through there may be a considerable amount of play when the key is introduced into the lock, preferably, one of the bits is bounded by surfaces which converge towards the central core of the key.

In known locks, the line joining the guide pins for the wards passes at a considerable distance from the centre of rotation of the key in the lock. In operation, this produces lateral forces which impede proper operation of the key. Improved smoothness in the operation of the lock is obtained in accordance with another aspect of the present invention by locating the guide pins for the wards on a line which passes through the centre of rotation of the key or closely adjacent thereto.

Also, in known locks, plates are provided which operate vertical bolts. These plates generally overlap one another substantially completely thereby setting up considerable friction forces.

In a further feature of the present invention, the guide pins for such plates are displaced with respect to the lines of the bolt control devices and act in conjunction with projections formed on the plates, so that none of the plates are overlapped by any other plate.

Finally, in known locks the guide of the socalled tail which is intended to operate a draw mechanism and supports the lever which operates the half-turn bolt is not entirely satisfactory. In a further aspect of the present invention, the tail is guided with respect to the frame of the lock by means of a slot through which the tail projects and by a pin on the frame which engages in a slot in the tail, and is also guided with respect to a control plate by engaging the pin which moves the plates for the vertical bolts and by engaging the pin for the half-turn bolt lever, one end of the latter pin engaging the tail and the other end engaging the control plate, thereby ensuring effective and precise guidance of all of the parts.

One embodiment of a lock in accordance with the present invention will be further described, by way of example, with reference to the accompanying drawings, all of which show a lock as viewed from the side thereof which is to be placed against a door. The drawing show various sequential steps during the assembly of the components.In the drawings: Figure 1 shows a frame of the lock in which is mounted a tail of the lock and a mechanism for a half-turn bolt, Figure 2 shows the parts seen in Figure 1 but having control plates for vertical bolts fitted thereto, Figure 3 shows the parts seen in Figure 2 but having a control plate and its corresponding bolts fitted thereto, Figure 4 shows the parts seen in Figure 3 but with a first ward fitted thereto, and Figure 5 illustrates a cross-sectional view of the keyhole and the corresponding key on a larger scale than Figures 1 to 4.

In the drawings, there is shown a frame which is affixabie to a door by means which are not shown. The frame includes slots, not shown, through which the tail and the mechanisms operating vertical bolts can pass. Apertures, also not shown, for the passage of the bolts are also provided. The frame further comprises a keyhole 2, 3, 4 for the introduction of a double bit key, a slot or window 5 for receiving a pin connected to an internal knob by means of which the half-turn bolt can be operated from internally a pair of pins 6 for guiding the wards of the lock, two pins 7, 8 for guiding plates which operate the vertical bolts and a pin 9 for guiding the tail of the lock.

The keyhole for the lock (and the corresponding key) has a cross-section seen more clearly in Figure 5. It has a central circular core 2 which defines the axis of rotation of the key, a first bit 3 which extends tangentially to the core 2 and which is bounded by planes which extend parallel to each other, and a second bit 4 which is also tangential to the core 2 but which is disposed on the opposite side of the axis of the core 2 to the bit 3. The two bits subtend an angle of other than 1 800 with one another. Advantageously, this subtended angle is between 1850 and 2000 measured in one direction (and therefore between 1600 and 1750 when measured in the other direction). This construction does not detract from the substantially flat nature of the key and thus means that the overall dimensions of the key may be kept small.Such a key is more robust than keys having radial bits and incorrect insertion of the key into the lock is prevented even if there is considerable play when the shaft of the key is inserted into the lock. It is preferable if, as illustrated, the second bit 4 is not bounded by parallel planes but by planes which converge in a direction towards the central core 2, the angle of convergence desirably lying between 30 and 100.

As is also shown in Figure 1, the two pins 6 which are intended to guide the wards of the lock (in the manner described above) are so located that the line torming them passes through the centre of rotation of the key, that is through the central core 2 of the keyhole, or at least passes closely adjacent thereto. By providing this arrangement, the lateral forces applied to the wards when the lock is operated are minimised and smoothness of operation is therefore improved. The lock arrangement includes a latch bolt comprising a bolt member 10 having an inclined striking end face 11 to provide an automatic latch closure, which end face passes through a corresponding hole formed in the frame 1. A pin 12 is provided on the member 10 which passes through the slot 5 and is attached to a knob (not shown) for manual operation of the latch from the inside of a room.The bolt member 10 is urged into a closed position by means of a spring 13 which is mounted on a pin 7, and also has a further pin 14 mounted thereon which is acted upon by means of a key. The pin 14 cooperates with a lever 1 5 which is provided with a restraining projection 1 6 (to be described further hereinafter). The lever also carries an operating pawl 17 which is located (in its operative position) in the path of the bit of the key when the latter is turned. The lever 15 is pivotally mounted on a pin 18, (also to be described further hereinafter), one end of which engages the internal end of the tail 1 9 of the bolt. The tail 19 of the bolt has a rectangular slot 20 formed therein which is engaged by the guide pin 9 of the frame 1.The tail 19 also has a hole 21 formed for therein receiving a drag pin forming part of a control plate 36. The tail 1 9 has a projecting portion 22 in which a hole 23 (Figure 2) is formed for connection to a tie rod which is intended to operate a draw mechanism.

The portion 22 projects externally of the frame 1.

The operation of the half-turn lever 1 5 is well known and will not be explained in any further detail.

As shown in Figure 2, there are two plates which operate upper and lower bolt members respectively. The plate for the upper bolt member is substantially in the form of a bayonet and comprises a body portion 29 having a projecting portion 24 which passes through a corresponding slot formed in the frame 1.

The portion 24 has a hole 25 formed therein for connection to a rod leading to the upper bolt member. The body portion 29 also has an extension portion 26 having a guide slot 27 formed therein in which engages the guide pin 8 of the frame 1. The two extension portions 24 and 26 are, however, not aligned with one another.

The plate 29 also has an oblique control slot 28 formed therein.

Similarly, the plate operating the lower bolt member is in the form of a bayonet and comprises a body portion 35 which carries two non-aligned extension portions 30 and 32. The portion 30 is provided with a coupling hole 31 for a rod which leads to the lower bolt and the portion 32 has a slot 33 formed therein in which engages the pin 7 of the frame 1. Plate 35 also has an inclined control slot 34 formed therein. The slots 28 and 34 are each engaged by the drag pin of a draw mechanism at one of their ends but diverge from each other. As plate 29 and 35 are bayonetshaped, that is to say, they are each asymmetric and are so shaped as to provide minimal overlap, large proportions of each of their surfaces are not in contact with the other plate so there is a considerable reduction in the friction between the plates during use.

The control plate 36, to which the horizontal bolts 37 of the lock are attached, is in the snape of a plate having an elongate slot or window 38 formed therein, the slot having teeth 39 which cooperate with the bits of the key. The plate 36 carries a drag pin 40 which passes through both of the inclined slots 28 and 34 formed in the plates 29 and 35 respectively so as to control the movement of the vertical bolts in a manner which is known. The pin 40 also engages in the hole 21 formed in the tail 19 of the lock thus forming a connection between the control plate 36 and the tail 19. This in known locks is the only connection between these two parts. However, the control plate 36 also has a hole formed therein which is so located as to be engaged by the pin 18 formed on the tail 1 9, which pin 18 is also engaged by the haif-turn lever 15.In this way, a second connection is made between the control plate 36 and the tail 19 which ensures their interconnection and also ensures that the parts of the lock which are subjected to horizontal displacement are guided in an optimum manner.

Finally, as is customary, the control plate 36 carries a square pin 41 which is intended to cooperate with the teeth of the wards.

Each of the wards (see Figure 4) is in the form of a plate 42 having slots 43 in which are the guide pins 6 formed on the frame 1 engage. A cam surface 44 is provided on each ward to cooperate with the bits of the key. In addition, each ward comprises a toothed window or slot 45 which co-operates with a square pin 41 of the control plate, a safety slot 46 which acts in conjunction with the restraining projection 1 6 formed on the half-turn lever 1 5 and a return spring 47 which is supported against one wall of the frame 1. The function of the wards is known and will not be explained in detail. The fundamental feature of the wards is that the guide slots 43 and the cam surface 44 of each ward are located substantially in a straight line since, as previously stated, the guide pins 6 on the frame and the circular core of the keyhole 2 are located substantially in the same straight line. The favourable consequences of providing such alignment have already been discussed.

The above-described features make an effective contribution both individually and, particularly, in combination to the design of a multi-bolt safety lock.

However, the key and keyhole configuration may find general application in any type of lock utilising a double bit key, the alignment of the wards is applicable generally to all types of ward lock and the substantially non-overlapping arrangement of the plates 29 and 35 is applicable to all types of lock having vertical bolts.

Claims (8)

1. A safety lock of the type having a double bit key wherein the shape of the keyhole, and that of the corresponding key comprise a central circular core (2), a first bit (3) extending tangentially to the core, and a second bit (4) extending tangentially to the core and which is directed generally away from the first bit (3), the two bits (3, 4) subtending an angle of other than 1800 with one another.

2. A lock as claimed in claim 1 wherein the angle between the two bits, when measured in one direction of rotation, lies between 1850 and 2000 (160" and 1750 when measured in the other direction of rotation).

3. A lock as claimed in claim 1 or 2, wherein one of the bits is bounded by two planes which are substantially parallel to one another and the other bit is bounded by planes which converge towards the central core at an angle of between 30 and 100.

4. A safety lock of the ward type comprising a frame for the lock, the frame including guide pins for wards of the lock, the guide pins and the centre of rotation of the key, as defined by the keyhole, lying at least substantially in a straight line, each ward including corresponding guide slots which co-operate with the guide pins of the frame and which slots lie in an at least substantially straight line including a cam surface which co-operates with the bit or bits of the key.

5. A safety lock of the type comprising a frame and at least two vertical bolts each operated by a plate member, each plate member comprising a body portion and two projecting portions, one projecting portion of each plate projecting externally of the frame and being connectable to rods operating the vertical bolts, the other projecting portion of each plate having an inclined slot formed therein in which a drag pin carried on a control plate engages, the two projecting portions on each plate being out of alignment with one another such that, in use, when the two plate members are located one on top of the other, the major proportion of the surfaces of the projecting portions on one plate are not in contact with the projecting portions on the other plate.

6. A safety lock of the type comprising a frame, a control plate and a tail operating a draw mechanism, the tail being guided by means of a guide slot in which engages a pin formed on the frame the tail being connected to the control plate by a drag pin mounted on the control plate, and by a pin on which a half-turn bolt is pivotally mounted, one end of said pin being inserted in a hole formed in the tail and the other end thereof being inserted in a hole formed in the control plate.

7. A safety lock comprising any combination of the features claimed in any one of claims 1 to 3 and/or 4 and/or 5 and/or 6.

8. A safety lock constructed and arranged to operate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.