GB2249805A

GB2249805A - Motorised bolt assembly

Info

Publication number: GB2249805A
Application number: GB9024671A
Authority: GB
Inventors: Walter Wilson Hugh Clarke
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-11-13
Filing date: 1990-11-13
Publication date: 1992-05-20
Also published as: GB9024671D0

Abstract

The assembly comprises a bolt 16 which is slidable longitudinally in a guideway 37 between two extreme positions by means of (a) propelling roller(s) 40 displaceable around the 54 axis of a shaft 38 by an electric servo motor 54 in an arcuate path of at least 180 DEG . The roller(s) 40 engages with a recess 32 in the bolt 16 whereby arcuate displacement of the roller 40 around the axis of shaft 38 is translated into longitudinal displacement of the bolt 16. As shown, the roller 40 is rotatably mounted between a pair of arms (46, Figure 4) rigidly attached to shaft 38; one end of shaft 38 carries a gear 50 meshing with gear 52 driven by motor 54. In its extreme position roller 40 is partially received in respective recesses 44a, 44b in surface 42 of a plate member 34. Details of the construction of bolt 16 are shown in Figures 8-10. Control of the driving of shaft 38 may utilise a limit switching technique (see Figures 13, 14, 15). <IMAGE>

Description

DESCRIPTION MOTORISED BOLT The present invention is concerned with motorised bolt mechanisms of the type wherein a bolt is adapted to be thrown between locked and unlocked positions by a servo motor.

Many different designs of motor driven locking bolts are known but these all have practical problems associated with them, mostly arising out of their relative mechanical complexity and hence their manufacturing ease and cost.

It is an object of the present invention to provide a motor driven bolt mechanism which is both relatively easy and cheap to manufacture whilst being reliable and robust in use.

In accordance with a first aspect of the present invention, a motorised bolt mechanism comprises a bolt which is slidable longitudinally in a guideway between two extreme positions by means of at least one propelling roller which is displaceable around a driving shaft by the servo motor in an arcuate path of at least 1800, the propelling roller being arranged to engage with a recess in the bolt whereby the arcuate displacement of the roller is translated into longitudinal displacement of the bolt.

In accordance with a second aspect of the present invention, a motorised bolt mechanism comprises a bolt which is slidable longitudinally in a guideway between two extreme positions by means of at least one propelling roller which is displaceable on a rigid linkage around a driving shaft in an arcuate path of at least 1800, the propelling roller being arranged to engage with a recess in the bolt whereby the arcuate displacement of the roller is translated into longitudinal displacement of the bolt and such that the rigid linkage lies dead-in-line, or beyond dead-inline, with the direction of movement of the bolt at both extreme positions of the roller along its arcuate path.

The invention is described further hereinafter, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a diagrammatic side elevation of one embodiment of a motorised bolt assembly in accordance with the present invention; Fig. 2 is a diagrammatic front elevation of the bolt assembly of Fig. 1; Fig. 3 is a front elevation of a plate for use with the bolt assembly of Figs. 1 and 2; Fig. 4 is a front elevation of a roller component of the bolt assembly of Figs. 1 and 2; Fig. 5 is an end view of the roller component of Fig. 4; Fig. 6 is a front elevation of a guide component of the bolt assembly of Figs. 1 and 2.

Fig. 7 is an end elevation of the guide component of Fig. 6; Figs. 8, 9 and 10 are front, end and side views, respectively, of a bolt component of the bolt assembly of Figs. 1 and 2; Figs. 11 and 12 are front and side elevations of the guide component, with the roller component of Figs. 4 and 5 mounted therein; Fig. 13 is a circuit diagram of one possible limit switch arrangment for controlling reversal of the bolt; Figs. 14 and 15 are front and side elevations of a contact switch arrangement for the limit switching; and Figs. 16a to 16e are diagrammatic side views illustrating the operation of the bolt assembly of Figs. 1 and 2.

The motorised bolt assembly of Figs. 1 and 2 comprises a metal lock case 10 having a front mounting panel 12 adapted to be fitted in a conventional manner within a door so that its front surface 12a lies flush with the vertically extending side surface of the door remote from its hinged edge. Alternatively, the lock case 10 could be mounted behind the vertical surface of a fixed door frame.

Slidably mounted in a rearwardly extending part 14 of the lock case is a metal bolt 16 which can be reciprocted in a manner to be described hereinafter for co-operating with an aperture 18 in a metal plate 20 fixed to the door frame or to the door, respectively, in the two formats mentioned above.

The bolt 16 is shown in detail in Figs. 8 to 10 and, in this embodiment, comprises a solid metal block 22 of generally rectangular cuboidal configuration having a transverse recess 24 in one major surface, a pair of transversely spaced, longitudinally extending recesses 26a, 26b, and a complex through-hole 28 disposed centrally relative to the recess 24 and consisting of a pair of transversely spaced, longitudinally elongate slots 30a, 30b interconnected by a longitudinally shorter slot 32.

The bolt 16 is slidably received within a guide component shown in Figs. 6 and 7 which comprises a metal plate member 34 having longitudinally extending, upstanding, parallel side walls 36 defining with the plate member 34 a guideway 37 along which the bolt 16 can be slidably displaced. The upstanding side walls 36 contain aligned bores 38 for receiving a shaft 38 (Fig. 4) carrying a roller 40, as described further hereinafter. The surface 42 of the plate member 34 defining the base of the guideway contains two identical transversely extending recesses 44a, 44b for receiving the roller 40 as described hereinafter.

Referring to Figs. 4 and 5, the roller 40 is mounted rotatably between a pair of arms 46 which are attached rigidly to the shaft 38 whereby rotation of the shaft about, its longitudinal axis causes the roller 40 to be rotated in an arcuate path about the latter axis. One end of the shaft carries a gear 50 which meshes with a further gear 52 driven by an electric servo motor 54 (Fig. 1).

As shown in Figs. 1 and 2 the guide component 34 is bolted to the rearwardly extending part 14 of the lock case by way of mounting holes 56 so that the guideway defined by the walls 36 and 42 is aligned with a rectangular opening 58 in the front panel 12 of dimensions which enable the bolt 16 to be displaced therethrough. The gear 50 on the shaft 38 is disposed so as to mesh permenantly with the gear 52 carried by the servo motor 54, which is also mounted to the part 14 of the lock case. The relative dimensions of the roller 40, arms 46 and recesses 44 and the height of the shaft 38 from the surface 42 of the guideway 37 are such that the roller 40 can be displaced by at least 1800 between two extreme positions, in one of which it is partially received in the recess 44a and in the other of which it is partially received in the recess 44b (see Fig. 11).In each of these latter extreme positions, the arms 46 lie parallel to the base 42 of the guideway, i.e. parallel to the direction of displacement of the bolt 16. These two extreme positions are illustrated in Figs. 16a and 16e, respectively, discussed further hereinafter.

The bolt 16 lies within the guideway 37 such that the roller 40 is aligned with the slot 32 in the bolt 16. Fig. 16a shows the fully retracted position of the bolt 16 wherein a lower part of the roller 40 is received by the recess 44a and an upper part of the roller 40 engages the lower end of the slot 32 in the bolt. Fig. 16b shows the condition that the shaft 38 has been rotated through 450 by the servo motor 54, the roller 40 having left the recess 44a and nowbeing fully received within the bolt slot 32. The engagement of the roller with the slot 32 causes the bolt to be somewhat displaced longitudinally along the guideway 37. Figs. 16c and 16d show the conditions wherein the shaft 38 has been rotated throgh 900 and 1350, respectively. In the condition of Fig. 16e the shaft has been rotated through 1800 and the lower part of the roller 40 has entered the other guideway recess 44b, the bolt having then been displaced to its maximum extent along the guideway so that it projects through the lock case aperture 58 to engage the aperture 18 in the plate 20 and thereby achieve the locking state of the bolt mechanism. Rotation of the shaft 38 in the opposite direction returns the bolt to its original position of Fig. 16a wherein the bolt mechanism is in its unlocked state. The slot 24 enables the longitudinal movement of the bolt to take place without interference by the shaft 38 which, as best seen in Fig. 12, lies above the level of the guideway base surface 42.

While the abovedescribed embodiment involves a servo motor to drive the locking shaft 38 through 1800, it can also be achieved using a limit switching technique. For example, the rotating arm 38 could move on to two insulated stops which are used to control the motor current directly by switching the bases of transistors.

One way in which the limit switch technique can be achieved is illustrated in Figs. 11, 12, 14 and 15. As shown in the latter Figures, an L-shaped piece of PCB 70 is fitted into the guide component 34 so that the arms 46 carrying the roller 40 stop against contacts 72 which are slightly proud of the track base 42. The PCB can be glued in place or fixed by screws. Pins 74 are provided to connect the contacts to the electrical circuitry.

Fig. 13 shows one possible circuit arrangement by which the motor 54 is controlled by reversing a switch 76. In this case, both limit switches 80 can be arranged in parallel to earth the base of an NPN transistor 78. In practice, other circuits may be needed in which separate earth return paths for the two directions of rotation of the motor are involved, in which case the two limit switches can be used separately, each with its own transistor.

Although the rotation of the shaft 38, and the arcuate path of the roller 40, are shown to be 1800, it is possible (and in some cases advisable) for the rotation to extend beyond 1800 at each end, i.e. as viewed in Figs. 16a and 16e the arms 46 will have passed slightly beyond the horizontal. To enable this to happen, the slots 44a, 44b in the guide component would have to be slightly deeper. Allowing the roller to be rotated slightly more than 1800, e.g. 5 at each end of its arcuate path, has the advantage of providing an over-locked condition which resists forceable unauthorised return of the bolt between its extreme positions. However, the extent of such over-locking is limited firstly in that the angle (beyond 1800) must not have a cosine much less than one otherwise it would reduce the effective throw of the bolt. Secondly, the angle of attack of the roller 40 must not be altered greatly at its starting points (Figs. 16a and 16e). If the roller is allowed to drop too far in the latter positions, the bolt 16 could clear the roller altogether in these positions so that the constraint on its longitudinal movement would be freed and its operation would be nullified.

The embodiment shown in the drawings uses a single roller 40 carried between a pair of parallel arms 46.

In an alternative embodiment, there can be two axially aligned rollers 40 connected to the shaft 38 by a single arm 46 disposed centrally between these two rollers. The latter arrangement is equally effective but is slightly more difficult to manufacture.

Claims

1. A motorised bolt mechanism having a bolt which is adapted to be thrown between stable locking and unlocking positions by a servo motor, wherein the bolt is slidable longitudinally in a guideway between two extreme positions by means of at least one propelling roller which is displaceable around a driving shaft by the servo motor in an arcuate path of at least 1800, the propelling roller being arranged to engage with a recess in the bolt whereby the arcuate displacement of the roller is translated into longitudinal displacment of the bolt.

2. A motorised bolt mechanism as claimed in claim 1, wherein the driving shaft is mounted in bearings at two sides of said guideway, the roller being disposed so that its axis lies parallel to that of the shaft.

3. A motorised bolt mechanism as claimed in claim 2, wherein the roller is connected to the shaft by way of a pair of arms.

4. A motorised bolt mechanism as claimed in claim 2, wherein there are two axially aligned, propelling rollers connected to the shaft by a single arm disposed therebetween.

5. A motorised bolt mechanism as claimed in claims 1, 2, 3 or 4, wherein, at each end of its arcuate path, the roller (or rollers) is partially received in a recess in the floor of the guideway.

6. A motorised bolt mechanism as claimed in any of claims 1 to 5 wherein longitudinal displacement of the bolt is constrained by engagement of the sides of the bolt recess with the roller periphery.

7. A motorised bolt mechanism as claimed in any of claims 1 to 6 wherein the guideway is formed from a separate guide component fixed to a main body component of the mechanism.

8. A motorised bolt mechanism as claimed in claim 7 wherein the guide component is of general U-shaped section, with the guideway defined between a base and upstanding side walls.

9. A motorised bolt mechanism as claimed in any of claims 1 to 8, wherein the shaft carries a first gear which is in permanent meshing engagement with a second gear driven by said servo motor.

10. A motorised bolt mecahnism as claimed in any of claims 1 to 9, wherein control of the motor is effected by limit switches positioned so as to be responsive to the roller reaching its extreme positions.

11. A motorised bolt mechanism having a bolt which is adapted to be thrown between stable locking and unlocking positions by a servo motor, wherein the bolt is slidable longitudinally in a guideway between two extreme positions by means of at least one propelling roller which is displaceable on a rigid linkage around a driving shaft in an arcuate path of at least 1800, the propelling roller being arranged to engage with a recess in the bolt whereby the arcuate displacement of the roller is translated into longitudinal displacement of the bolt and such that the rigid linkage lies dead-in-line, or beyond dead-inline, with the direction of movement of the bolt at both extreme positions of the roller along its arcuate path.

12. A motorised bolt mechanism substantially as hereinbefore described, with reference to and as illustrated in the accompanying drawings.