GB2141482A

GB2141482A - Latches

Info

Publication number: GB2141482A
Application number: GB8415195A
Authority: GB
Inventors: Donald Henry William Dover
Original assignee: Dover Roller Shutters Ltd
Current assignee: Dover Roller Shutters Ltd
Priority date: 1983-06-14
Filing date: 1984-06-14
Publication date: 1984-12-19
Also published as: GB8415195D0; GB2141482B

Abstract

A latch mechanism for an openable shutter of the type comprising a plurality of laths pivotally interconnected to form a planar closure. The latch mechanism comprises a handle 5 pivotted to a lath 1 at 6 and pivotally connected to a lever 9 at 8, which lever 9 is itself pivotally connected to a latch member 11 at 10. The latch member is slidable in saddle members 12, 13 by way of rolling elements 16, 17, 18, 19 constrained within respective recesses 20, 21, 22, 23 formed in the latch member. The operating direction A of the handle 5 is the same as the direction of opening of the shutter, so that only a single movement is required. In the embodiment of Fig. 4 the lever 5 retracts two latch bolts 11L and 11R. A barrel lock may be used to lock the mechanism. The bolt 11 may be in two parts linked by block 25 and pins 26. <IMAGE>

Description

SPECIFICATION Improvements in or relating to latches The present invention relates to latches of the type used to latch a door or other closure. The invention is particularly, but not exclusively, directed to latches for use in openable shutters such as are used on commercial vehicles and the like.

Such shutters generally comprise a plurality of horizontal laths, each being pivotally connected to an adjacent lath to form a planar closure. In order to open the shutter, the bottom lath is pushed upwards whereupon the laths, moving upwards within vertical tracks formed at the sides of the closure, are rolled onto a roller positioned across the top of the closure, or alternatively are moved onto horizontal tracks arranged near to the roof of the vehicle.

In the closed position, the shutter needs to be latched shut and this is generally achieved by arranging, on the bottom-most lath, a latch mechanism which engages in a pair of cams respectively positioned adjacent the ends of the bottom-most lath on the vehicle body.

These latches are operated by respective push buttons which must first be pushed before the shutter can be raised. These buttons can be awkward to operate, particularly for example in an emergency, in view of the combined action necessary-pushing the buttons and pulling upwards on the bottom lath-which is necessary to raise the shutter.

In a first aspect, the present invention seeks to remedy this inconvenience by providing a latch mechanism comprising a base member, a handle pivotally mounted on said base member for rotation about a limited arc, a latch member slidably mounted on said base member and a lever pivotally connected between said handle and said latch member, the arrangement being such that rotation of said handle acts, through said lever, to cause sliding movement of said latch member. The base member may be attached to the closure to be latched, or alternatively the closure itself may form all or part of the base member.

It will be seen that if, for example, the above latch is attached to or forms part of the bottom-most lath in a roller shutter, the mechanism can be arranged such that the rotation of the handle to release the latch can be the same movement that is needed to raise the shutter, thus eliminating the requirement for two distinct operations, as indicated above. Thus, in the preferred embodiment, the handle is arranged such that it extends approximately horizontally from its pivot and remains, in fact, approximately horizontal throughout its limited arc of movement.

For this purpose, the handle is equipped with an area which, when the latch is fitted, occupies an approximately horizontal orientation and may be raised by hand to rotate the handle about the pivot. Preferrably spring means are provided in order to normally bias this horizontal area of the handle into its lowermost position. The lever is positioned in such a way as to convert the rotating motion of the handle into the sliding (linear) motion of the latch member. Various alternative positions are possible. For example, said further lever may be pivotted in such a way as to define two arms, one used for hand raising as aforsaid and the other pivotally attached to the first-mentioned lever. Alternatively, said further lever may be pivotted at one end, and have the firstmentioned lever pivotally mounted at the other end, with the intermediate section being used for hand raising.

A further problem occurs in latches used in situations where a long latch member is used such as in openable shutters fabricated from horizontal laths. This problem concerns stiffness and even jamming of the latch member in its constraints. These latter generally take the form of one or more saddle members attached to the closure and defining a passage of such shape and size that the latch member is a sliding fit therein.

The second aspect of the present invention seeks to overcome this problem associated with present latches by forming, in the interior surface of the passage, or the exterior surface of the latch member, or both, a recess in which fits a rolling member such as a ball or roller. In an embodiment, the recess is elongate in the direction of movement of the latch member so that the rolling member may roll along the recess as the latch member is moved within the passage. The number of recesses so formed in any one saddle depends upon the circumstances, for example on the length of the passage and on the direction of the forces acting on the latch member. One recess may sometimes be adequate but more often at least two will be desirable, positioned on opposite sides of the latch member and possibly staggered along the length of the latch member.In another alternative, pairs of recesses may be positioned opposite to one another across the latch member, one or more spaced pairs of recesses being used in each saddle member. It would also be possible to position the recesses at other angular orientations about the geometric centre of the latch member-for example, with a square or rectangular latch member a recess may be formed on each of the four 90 apart surfaces of the passage/latching member.

Although the technique embodied in this second aspect of the invention is especially suitable for the latch of the first aspect of the invention, its use is not limited thereto and will find wide application in the field of latches.

In order that the invention may be better understood, several embodiments thereof will now be described by way of example only and with reference to the accompanying drawings in which: Figures 1A and 1 B show respectively front views of the left and right hand ends of an embodiment of a latch according to the present invention shown mounted on a lath; Figures 2 and 2B correspond to Figures 1 A and 1 B respectively, but show plan views, Figure 2A being a sectional view; Figure 3 is a diagram of an alternative lever arrangement; Figure 4 is a diagram showing the use of a single latch for both ends of the lath; and Figure 5 is a diagram showing how a lock may be used with the latch of the present invention.

Referring to Figures 1 and 2, the latch is shown mounted on a lath 1. in Figure 1A, the lath itself is not shown; only its position is indicated by dotted lines. The lath 1 is one of a series of parallel laths making up a shutter.

Normally lath 1 will be the bottom-most lath, though this is not necessarily the case. Each lath takes the form of an elongate section, usually of aluminium or similar, having a front face 2 which, when fitted, faces the exterior.

The latch of the invention is attached to this front face. The latch comprises a block 3, for example of aluminium, which, in use, faces the exterior. The block is formed with a rectangular through-aperture 4 in which is movably mounted a handengageable lever 5 pivotted with respect to block 3 about point 6.

Beyond the confines of the aperture 4, and at the opposite end to the pivot point 6, the lever 5 is cranked at point 7 and pivotally connected at pivot point 8 to a link lever 9.

The link lever 9 is in turn pivotally connected at pivot point 10 to a latch member 11.

The latch member is slidably mounted in a direction parallel to the lath. For this purpose two saddle members 12, 1 3 are attached to the back of the front face 2 and define respective longitudinal through apertures 14, 1 5 of rectangular shape and of such a size as to allow sliding fit of the latch members.

Motion of the latch member within apertures 14, 1 5 is assisted by small roller members 1 6 to 1 9 whose rolling axis is transverse to the direction of motion of the latch member. Each roller member is located in a respective slot 20 to 23 machined across the width of the latch member, and elongate in the direction of motion of the latch member to allow rolling of the roller members as the latch member is moved. Each roller member is of such a size as to be a rolling fit between the bottom of its respective slot and the adjacent inside surface of the through aperture in the saddle member.

The end of the latch member protrudes beyond the end of the lath and is intended to engage a conventional latch closing cam 24 in the usual manner. The positioning of the roller members with respect to the saddle members depends upon the expected forces on the latch member. Thus in the saddle member 12, the load applied to the latch member will be in the direction of arrow B as the user attempts to open the shutter, ana this has dictated the particular diagonal arrangement of roller members 16 and 17.

Likewise, in the saddle member 13, the forces generated by the lever arrangement 5/9 are in the direction of arrow C and the roller members 1 8 and 1 9 are arranged accordingly.

The latch member 11 is in two parts linked by a block 25 and pins 26. The outer end 27 of the latch member is cranked inwards at 28 in order to bring it into a suitable position to engage the cam 24. The other end 29 of the latch member has a section enclosed by a spring 30 acting between the block 25 and saddle member 1 3 in order to normally bias the latch member into the left-most (extended) position. Movement of the latch member in the leftwards direction is limited by a pin 31 which abuts the saddle member 1 3.

In a practical installation, the lath 1 will be fitted with two latches such as described above. Figures 1A and 1B and Figures 2A and 2B show the arrangement of left and right hand latches operating respective latch members 11 engageable in turn with respective cams 24. In order to raise the shutter, the user simply places his left and right hands respectively into the aperture 4 beneath the lever 5 in the left and right hand latches. The hands are now raised in the manner required to raise the shutter whereupon the respective levers 5 turn about their pivots as shown by arrow A and, via link levers 9, retract the latch members 11, thus allowing the shutter to be unlatched and raised in one simple movement.

Various other lever arrangements are possible, an alternative being illustrated diagrammatically in Figure 3. Here, the pivot point 6 of the lever 5 is moved to be coincident with the crank point 7. The remaining parts are arranged similarly and the same reference numerals are used to illustrate the construction.

Figures 1 and 2 illustrate an arrangement in which two latches are used on the lath 1, one for the left hand, one for the right. In an alternative arrangement, illustrated diagrammatically in Figure 4, only one latch is provided (in this case, the righthand one), the motion to the left-hand latch member 11 being transmitted via a series of links. The lever arrangement of Figures 1, 2 is shown diagrammatically as acting directly on a righthand latch member 11 R. This latter is pivotally connected to a link lever 32 which in turn is pivotally connected to an arm 33 pivotally mounted about its centre point on the lath 1 (not shown). The arm 33 is pivotally connected to a further link lever 34 which connects to the left-hand latch member IIL via a link lever 35.The left hand latch member 11 may alternatively be cranked as shown in Figure 2A, in which case the link lever 35 is unnecessary. Arrows show the direction of movement of the various components, following application of an upwards force A on the lever 5. In this construction, the right hand latch (not shown) is simply a dummy, comprising only a block 3 and finger aperture 4.

Figure 5 illustrates diagrammatically a locking mechanism for the double latch arrangement illustrated in Figures 1 and 2. Here the inner ends of the left and right hand latch members are extended as shown under reference 36. A lock 37 is mounted centrally on lath 1 (not shown) between the extended ends 36. The lock comprises a barrel which unlocks to allow a centrally pivotted lever 38 to twist to allow inwards movement of the latch members 11. In the locked position, the lever 38 effectively jams both latch mechanisms, preventing retraction of the latch members from behind the respective cams 24.

Claims

1. A latch mechanism comprising a base member, a handle pivotally mounted on said base member for rotation about a limited arc, a latch member slidably mounted on said base member and a lever pivotally connected between said handle and said latch member, the arrangement being such that rotation of said handle acts, through said lever, to cause sliding movement of said latch member.

2. A latch mechanism as claimed in claim 1 wherein the handle is elongate and wherein its pivot point is positioned at one end thereof, the other end being pivotally connected to said lever.

3. A latch mechanism as claimed in claim 2 wherein the handle is cranked at a position intermediate its pivot point and the pivot point of said lever.

4. A latch mechanism as claimed in claim 1 wherein the handle is elongate and is pivoted near one end in such a way as to provide a first, longer, section which may be moved by hand and a second, shorter, section which is pivotally connected to said lever.

5. A latch mechanism as claimed in claim 4 wherein said handle is cranked at its pivot point.

6. A latch mechanism as claimed in any one of the preceding claims wherein said latch member is mounted on said base member by means of one or more blocks each having a through-bore in which said latch member may slide and wherein, within the confines of the or at ieast one of said blocks, one or both of said latch members or bore is formed with a recess in its surface facing the other, said recess carrying a rolling element sized such as to permit easy movement of the latch member in the bore.

7. A latch mechanism substantially as herein before described with reference to the accompanying drawings.

8. A shutter comprising a plurality of pivotally interconnected laths arranged to form a planar closure, and a latch mechanism as claimed in any one of the preceding claims attached to one of said laths in such a way that the latter forms said base member.

9. A shutter as claimed in claim 8 wherein the handle is oriented in such a way that its direction of movement in order to unlatch the mechanism is the same as the direction of movement required to open the shutter.

10. A shutter as claimed in either one of claims 8 or 9 wherein two said latch mechanisms are mounted on the lath, one for each end of the lath.

11. A shutter as claimed in any one of claims 8, 9 or 10 further including locking means operable, in the locked position, to prevent said sliding movement of the or each latch member.