GB2312236A

GB2312236A - Shoot bolt drive mechanism

Info

Publication number: GB2312236A
Application number: GB9704893A
Authority: GB
Inventors: Jason David Paddock
Original assignee: CHADWICK ANTHONY; Trojan Hardware and Design Ltd
Current assignee: CHADWICK ANTHONY; Trojan Hardware and Design Ltd
Priority date: 1996-04-17
Filing date: 1997-03-10
Publication date: 1997-10-22
Anticipated expiration: 2017-03-10
Also published as: GB9707502D0; GB9705294D0; GB9607908D0; GB2312236B; GB2313618B; GB9704893D0; GB2313617A; GB2313617B; GB2313618A

Abstract

In a drive for a bi-directional shoot bolt mechanism, for securing doors and windows, a quadrant gear 14 is arranged to drive two racks 18,20, one rack being secured to each of two bolt arms 22,24. One rack 18 engages the quadrant gear 14 directly. The other rack 20 is driven through a pinion wheel 16 which is itself in engagement with a second set of teeth on the quadrant gear 14, offset by half of one pitch, thereby to result in the two bolt arms 22,24 being driven in opposite directions upon rotations of the quadrant gear 14. A larger quadrant gear 52 and two reversing pinions 54,56 (Figure 8) may instead be employed to achieve a longer throw of the bolt arms 22,24.

Description

SHOOT BOLT DRIVE MECHANISM This invention is concerned with improvements in or relating to bidirectional shoot bolt mechanisms such as are used for securing opening windows and doors in closed positions.

Such mechanisms comprise a housing for a drive mechanism which is adapted to be accommodated in a recess in an edge member of a window or door. Two ordinarily strip-like bolt arms extend in opposite directions from a front face of the drive mechanism, to be moved longitudinally by the mechanism. The bolt arms are usually adapted to be accommodated in shallow channels formed in the edge member, end portions of the arms being projectable beyond guide members, secured to corners of the window or door, for engagement with keeps on an adjacent window or door frame. In an open condition of the mechanism, the bolt ends are drawn back from the keeps to the guide members to permit the window or door to be opened.

For securement in edge members of standardised extruded section, it is necessary that the dimensions of the drive mechanism housing come within certain predetermined limits. In particular, the depth of the mechanism from front to rear is so limited. For operation by means of a handle, the mechanism ordinarily comprises a primary drive gear (commonly a quadrant gear) which is slotted axially to receive a drive spindle on which the handle is fixed. It is necessary that the spindle axis be well removed from the front face of the edge member and, therefore, that the primary drive gear be positioned as rearwardly as possible within the housing. Intermediate drive mechanism, acting between the primary drive gear and transmission links of the bolt arms, needs to be accommodated between the primary drive gear and the front face of the mechanism.

This arrangement means that there tends to be a front to rear thrust on the primary drive gear in operation. The thrust has to be borne by the housing, and as a consequence of this, some of the available depth for the mechanism needs to be occupied by a rearmost portion of the housing supporting the primary gear. This in turn has limiting implications for the design of the primary drive gear and intermediate mechanism.

It is an object of the present invention to provide improvements relating to the design of shoot bolt drive mechanisms which enables more effective use to be made of the limited space available.

The invention provides, in one of its aspects, a shoot bolt mechanism comprising a primary drive gear arranged upon rotation to drive two bolt arms, each bolt arm being driven by means of a toothed rack, and one of the racks being engaged with said primary drive gear and the other of the racks being engaged with a reversing pinion which also is engaged with said primary drive gear, whereby said two bolt arms become driven in opposite directions upon rotation of said primary drive gear.

Such an arrangement can provide the advantage of being very compact, and can also enable the reversing gear to be well constrained.

The primary drive gear may be a quadrant gear which presents teeth around an arc of, typically, between 135 and 1800.

In a preferred construction of primary drive gear formed by casting, the gear presents two sets of teeth which are circumferentially off-set from one another, one set being arranged to be engaged by said one of the racks and the other being arranged to be engaged by the reversing pinion. The two sets may be off-set by half a pitch.

In order to achieve a longer throw of the bolt arms, or for other reasons, such mechanism may comprise two (or more) reversing pinions which are arranged to be engaged successively by said other of the drive racks, the pinions being spaced circumferentially about the primary drive gear.

There now follows a detailed description, to be read with reference to the accompanying drawings, of a shoot bolt mechanism which illustrates the present invention by way of example.

In the accompanying drawings: Figure 1 is a side view of an operating mechanism (with a housing half removed) in an open condition of the shoot bolt mechanism; Figure 2 is a front face view of the operating mechanism, seen in the direction of arrow A in Figure 1; Figure 3 is an enlarged view in section on line III-III of Figure 1; Figure 4 is a view similar to Figure 1 but with the mechanism in a closed condition; Figure 5 is a view similar to Figure 2 but with the mechanism in its closed condition; Figure 6 is an enlarged view in section on line VI-VI of Figure 4; Figure 7 is a side view of a second operating mechanism in an open condition, a housing half and one drive rack being removed; Figure 8 is a view similar to Figure 7 but with the omitted drive rack restored; Figure 9 is a view similar to Figure 7 but with the mechanism in a mid-way position of adjustment between fully open and fully closed conditions; Figure 10 is a side view of a quadrant gear having a staggered tooth form; and Figure 11 is a view in section on line XI-XI of Figure 10.

An operating mechanism of a bi-directional shoot bolt, for securing a window or door, is shown in Figures 1 to 6. Two halves 10,12 of a housing provide support between them for a primary-drive quadrant gear 14, a reversing pinion 16 and first and second racks 18 and 20 of two transmission links comprising bars 22,24 of oppositely directed bolts.

The quadrant gear 14 is formed with an axially aligned slot 26 of square cross-section to receive a drive spindle which is secured to an operating handle (spindle and handle not shown, but can be of conventional form). As seen in Figures 1 and 3, the slot 26 extends through a cylindrical hub-forming portion 28 of the quadrant gear which is of equal axial length to the width of the housing. A tooth-providing crest 30 of the gear extends about part only of the circumference of the hub-forming portion 28, being of shorter length than the hub-forming portion and being positioned centrally (in the axial direction). At each end of the gear, a groove 32,34 is cut into the root of the crest, adjacent to the cylindrical surface of the hub-forming portion 28, the groove extending about the hub-forming portions for the full extent of the crest 30.

The grooves 32,34 provide part-circular, open-ended, recesses to receive flanges 36,38, of corresponding dimensions, projecting inwardly from the housing halves 10,12; the grooves 32,34 and flanges 36,38 are concentric with the axis of the quadrant gear 14, and the flanges 36,38 bound circular openings 40,42 in which opposite end portions of the hubforming portion 28 of the gear are received.

The flanges 36,38 of the housing halves provide radial support for the quadrant gear in the direction away from the racks 18,20 and reversing pinion 16. This support reduces the demands on the housing halves at the openings 40,42 which form further bearings for the hubforming portion 28 of the quadrant gear. As a consequence, it is not necessary for the housing to surround the quadrant gear completely and, as best seen in Figures 1 and 4, the rearmost surface 44 of the hubforming portion of the gear is exposed through an opening in the housing and is generally flush with a rear face 46 of the housing. Rotation of the quadrant gear is so guided by the combination of the flanges 36,38 and the part-cylindrical bearing surfaces formed by the housing halves around the openings 40,42.

The teeth of the quadrant gear are held in engagement with the teeth of the first rack 18. Upon rotation of the quadrant gear clockwise from a starting position (shown in Figure 1) to a finishing position (shown in Figure 4) the rack and its associated transmission bar 22 are driven from left to right, as seen in the drawings, the two quadrant positions corresponding with fully open (Figure 2) and fully closed (Figure 5) conditions of the shoot bolt mechanism.

The quadrant gear teeth are also held in engagement with the reversing pinion 16, and the pinion is held in engagement with the teeth of the second rack 20. In rotating the quadrant gear from its starting position to its finishing position the second rack and its associated transmission bar 24 are, therefore, driven in the opposite direction from the first rack and transmission bar (i.e. from right to left).

The pinion 16 and first rack 18 are positioned side by side (i.e.

axially spaced) on the quadrant gear and the two racks 18,20 are likewise spaced axially of the gear, the teeth of the second rack 20 being at a greater radial distance from the axis of the gear for accommodation of the reversing pinion therebetween. The transmission bars 22,24 are of flat strip form and are retained in place by means of a cover plate 48 applied to the front face of the housing.

A long-throw version of the drive mechanism just described is illustrated by Figures T and 8. Two halves 50 (only one shown) of a housing provide supp t between them for a primary drive quadrant gear 52, two reversing pinions 54,56, and first and second drive racks 58,60 of two transmission links.

The first drive rack 58 engages the drive quadrant 52 directly, in the manner of the first rack 18 engaging the quadrant gear 14 of the first embodiment.

The second drive rack 60 is arranged to be driven successively by the two reversing pinions 54,56, which are in engagement with the drive quadrant at circumferentially-spaced positions about the quadrant. At a mid-way position of the quadrant (Figure 9) half-way through an opening or closing operation, both reversing pinions are in engagement with both the quadrant and the drive rack.

It is to be observed that the housings of the two embodiments described are of similar overall dimensions, but the quadrant gear 52 of the long-throw version is of substantially larger diameter than the quadrant 14 of the first version in order to provide for greater movement of the two racks from the same 90" rotation of the associated quadrant gear. The use of two reversing pinions54,56 enables the drive mechanism to be accommodated within substantially the same housing size.

A preferred design of cast quadrant gear, usable in either of the two versions of drive mechanism described, is shown in Figures 10 and 11. The gear presents, around its circumference, first and second sets 62,64 of teeth for engagement with the first drive rack 18,58 and the reversing pinion (or pinions) 16,54,56 respectively. The tooth sets are off-set from one another by one half of one pitch, the two sets meeting on a split plane P of the casting. In this manner a compact yet very strong gear is produced.

Claims

1. A shoot bolt mechanism comprising a primary drive gear arranged upon rotation to drive two bolt arms, each bolt arm being driven by means of a toothed rack, and one of the racks being engaged with said primary drive gear and the other of the racks being engaged with a reversing pinion which also is engaged with said primary drive gear, whereby said two bolt arms become driven in opposite directions upon rotation of said primary drive gear.

2. A shoot bolt mechanism according to claim 1 in which the primary drive gear is a quadrant gear.

3. A shoot bolt mechanism according to either of claims 1 and 2 in which the primary drive gear presents two sets of teeth which are circumferentially off-set from one another, one set being engaged by said one of the racks and the other being engaged by the reversing pinion.

4. A shoot bolt mechanism according to claim 3 in which the two sets of gear teeth are off-set by one half of one pitch.

5. A shoot bolt mechanism according to any one of claims 1 to 4 in which there are two reversing pinions arranged to be engaged successively by said other of the drive racks, the two pinions being spaced circumferentially about the primary drive gear.

6. A shoot bolt mechanism substantially as hereinbefore described with reference either to Figures 1 to 6 or to Figures 7,8 and 9 of the accompanying drawings.