GB2175639A - Latch assembly - Google Patents

Abstract

A latch assembly, which is movable within a housing defining a channel, is of two-part construction. One part 26 is drivable to move the latch assembly from a retracted position to an extended position and vice versa. The other member 27, which extends from the housing is movably secured to the first member but is biassed away from the first member. In the preferred embodiment a screw 31 passes through a bore in the first member and engages a threaded bore in the second member, whilst two compression springs 32, 33 bias the second member away from the first member. <IMAGE>

Description

SPECIFICATION Improvements in or relating to a latch THE PRESENT INVENTION relates to a latch and more particularly relates to a latch suitable for use in retaining a door or panel in a closed condition within a frame or the like.

According to this invention there is provided a latch for use in retaining a door or panel in a closed condition within a frame or the like, said latch comprising a housing, the housing being adapted to be mounted securely in position, the housing containing a slidable latch assembly and incorporating means for moving the assembly from a retracted position to an extended position and vice versa, the latch assembly comprising two members which are connected together but which are movable relative to each other, and which are resiliently biassed apart, the first of said members engaging said driving means and the second of said members projecting from the housing.

The latch may be mounted on the door or panel, so that said projecting member can engage a frame for the door or panel to retain the door or panel in the closed condition. Alternatively, however, the latch may be mounted on the frame, and the projecting member may engage the door or panel when it is closed.

Preferably the first member of the latch assembly has a through-going bore therein, and the second member of the latch assembly has a screw-threaded bore co-aligned with the said bore in the first member, a screw having a head portion engaging the first member passing through the bore in the first member and being screw threadedly engaged with said screw threaded bore to connect the members together. It will be appreciated that the screw may be turned to adjust the maximum spacing between the members. The second member will always be able to move towards the first member against the resilient bias until the members touch or the resilient biassing means are fully compressed.

Preferably, the first and second members of the latch assembly are biassed apart by means of coiled compression spring means located between the members, opposed ends of the compression spring means engaging said two members respectively.

Conveniently two compression springs are provided, the compression springs being symmetrically located with reference to the means connecting the said members, means being provided to retain the ends of said springs in predetermined positions on said members.

Alternatively one compression spring is provided, said spring surrounding the portion of the screw extending between the first member and the second member.

Advantageously the projecting member of the latch assembly is provided with a chamfered or inclined face to engage said frame.

In a preferred embodiment the first member of the latch assembly is provided with a groove therein which receives a peg provided on a rotary cam member, means being provided to rotate the cam member to move said latch assembly from the retracted position to the extended position and vice versa.

Preferably said rotary cam member is provided with a recess therein adapted to receive a drive rod, rotation of the drive rod causing rotation of the cam.

Conveniently a drive rod is provided, engaged with said rotary cam, the drive rod engaging a knob, rotation of the knob effecting rotation of the rotary cam, and advantageously a screw is provided passing through a bore provided in the knob and engaging a screwthreaded bore provided in the rotary cam to retain the knob in position.

Preferably a substantially cylindrical element is provided between the rotary cam and the knob to retain the knob at a spaced position from the rotary cam to facilitate use of the latch on a door or panel of substantial thickness.

Conveniently the housing comprises means defining a channel in which the latch assembly is slidably mounted.

The housing may be designed to provide ready access to the said screw which connects the members together, thus facilitating an adjustment of the spacing between the said members.

Alternatively the housing comprises a substantially "U" section channel provided with flanges thereon by means of which the channel may be secured to a door, panel or the like.

Preferably said channel is provided with a recessed portion providing access to said driving means.

Conveniently said driving means comprises an element protruding from the first of said members, adapted to cooperate with a drive linkage.

Preferably the first member comprises a drive member which is of generally cuboid form, the second member comprising a detent-carrying member having a portion abutting part of the drive member and a portion carrying a detent face.

The members constituting the latch assembly may be fabricated from a plastics material which is electrically conductive, such as nylon incorporating molybdenum di-sulphide, and the components apart from the two members of the latch assembly may be fabricated primarily from stainless steel.

In order that the invention may be more readily understood, and so that further features thereof may be appreciated, the invention will now be described with reference to the accompanying drawings in which: Figure 1 is an exploded view of one em bodiment of a latch in accordance with the invention with part thereof cut-away; Figure 2 is a front view of a latch assembly forming part of the latch of Fig. 1; Figure 3 is a horizontal cross-sectional view taken on the line Ill-Ill of Fig. 2; Figure 4 is a front elevational view of the latch of Fig. 1 in the assembled condition; Figure 5 is a horizontal cross-sectional view of the latch of Fig. 4 taken on the line V-V; Figure 6 is a vertical sectional view of the latch of Fig. 4 taken on the line VI-VI;; Figure 7 is a cross-sectional view, corresponding to Fig. 6, showing a modified latch in accordance with the invention; Figure 8 is an exploded view of a further embodiment of the invention, Figure 9 is a side view of the embodiment of Fig. 8 when in the latched position, and Figure 10 is a part sectional, part exploded view of a latch assembly forming part of the latch of Figs. 8 and 9.

Referring initially to Fig. 1 of the accompanying drawings a latch comprises a housing 1 which is in the form of a "U" sectioned channel portion 2 having outwardly extending flanges 3, 4 at the free ends of the arms of the "U". Each flange is provided with four holes 5 therein. At one end of the "U" shaped channel a portion of the housing is bent or otherwise formed to constitute an end wall 6 closing the channel, which has an aperture 7 therein.

A latch assembly 8, which will be described hereinafter in greater detail, is provided which can be slidably positioned within the "U" sectioned channel 2.

A rotary cam member 9 is provided, which is of circular configuration. The outer periphery of the rotating cam member is recessed 10, and the rotating cam member is retained with the recess 10 engaged with cut-out semi-circular portions 11, 12 provided in two abutted plates 13, 14. The plates 13, 14 are provided with apertures 15 which can be co-aligned with apertures 5 provided in the housing 1.

Four rivets 16 are provided which pass through four of the co-aligned pairs of holes to secure the described components together.

A hexagonal drive shaft 17 is provided, one end of which engages a central hexagonal recess 18 formed in the front face of the drive cam 9, the other end of which engages a corresponding recess 19 in a knob 20. A recessed through-going bore 21 is provided in the knob 18 which accommodates a screw 22 which is screw-threadedly engaged into a screw-threaded bore 23 provided in the rotary cam 9.

The rotary cam 9 is provided with a peg 24 on the rear face thereof which engages with a slot 25 provided in the latch assembly 8 so that when the rotary cam is rotated, by actuation of the knob 20, the peg moves laterally, causing the latch assembly 8 to move from a position in which a substantial part of the assembly 8 projects from the housing 1 to a retracted position and vice-versa.

The latch assembly 8 is shown more clearly in Figs. 2 and 3 of the accompanying drawings. As can be seen, the latch assembly 8 is constituted by two substantially rigid components, namely an inner component 26 and a detent component 27. The inner component 26 is of substantially cuboid structure, but defines the recess 25 on a front face thereof.

The recess 25 is a substantially vertical recess extending down from the top edge of the member 26.

The detent member 27 is again of generally cubic construction, but the part of the front face of the member 27 that is remote from the member 26 is chamfered rearwardly, 28, thus forming a chamfered face which can be seen most clearly in Fig. 3 of the accompanying drawings.

A counter-sunk through-going bore 29 is provided in the member 24, the large end of the counter-sunk bore being at a position remote from the detent member 27. An internally threaded blind bore 30 is provided in the member 26, co-aligned with the adjacent end of the bore 29 so that a screw 31 may be inserted in position through the counter-sunk bore 27 and screw threadedly engaged in the blind internally threaded bore 30.

Two compression springs 32, 33 are located in position between the inner member 26 and the detent member 27, the springs being symmetrically disposed with relative to the screw 29. Each end of each spring 32, 33 is accommodated in an appropriate recess formed in the abutting face of the member 26 or 27.

The springs serve to bias the members 26 and 27 apart, but by rotating the screw 31 it is possible to draw the member 27 towards the member 26, thus compressing the springs, or it is possible to permit the member 27 to move away from the member 26, thus releasing the compression in the springs.

Thus it will be appreciated that the overall length of the latch assembly 8 may be adjusted by rotating the screw 31.

The aperture 7 provided in the end wall 6 provides access to the head of the screw for an appropriate screw driver.

The latch is assembled by inserting the latch element 8 within the channel 2 of the housing 1, locating the peg 22 of the rotary cam 9 in the slot 25, and then engaging the recesses 11, 12 on the plates 13, 14 with the recessed periphery 10 of the rotary cam 9. The plates 13, 14 are then riveted in position.

The housing 1 may then be screwed to a door or panel 34 (see Fig. 6) with which the latch is to be used, to fasten it in position, using screws passing through the holes provided in the flanges 3, 4 on the housing 1 and the co-aligned holes in the plates 13, 14 not occupied by the rivets. An aperture will be provided in the door or panel in front of the rotary cam 9.

The hexagonal drive shaft 17 will have one end thereof inserted in a the hexagonal recess 18 formed centrally in the rotary cam 9, and the other end of the hexagonal drive shaft 17 will be accommodated in the recess 19 formed in the knob 20. Alternatively the hexagonal drive shaft 17 may be formed integrally with the knob 20, or may be formed integrally with the rotary cam 9.

The screw 22 may then be inserted through the counter-sunk bore 21 in the knob, and engage with the screw threaded blind bore 23 formed in the rotary cam 9, thus firmly securing the knob to the cam 9. As the knob is rotated, so the cam will rotate, thus driving the described latch element into, and out of, the housing. The knob 20 is larger than the hole in the door or panel 34, thus providing a neat finish, and also helping to maintain the latch in position.

As can be seen in Fig. 6 the embodiment thus described is intended for use with a relatively thin door or panel 34, but as can be seen in Fig. 7 it is possible to devise a modified embodiment of the invention for use with a much thicker door or panel 34A. In this embodiment, which very closely resembles embodiment described above, a tubular spacer element 35 is provided which has a diameter slightly greater than the diameter of the rotary cam member and also slightly greater than a circular boss formed on the underside of the knob. The tubular spacer element may be cutoff at a desired length from a long tube or the like. The spacer is located at one end surrounding the rotary cam and abutting the plates 13, 14, and the other end thereof receiving the boss provided on the underside of the knob.In this embodiment the hexagonal drive shaft 1 7A is much longer than the drive shaft 17 shown in Fig. 1, and also the screw 22A is much longer than the screw 22 provided in Fig. 1. It can be seen that the tubular extension member passes through an appropriate aperture formed in the door or panel, and in all other respects this embodiment of the invention is the same as that described above.

It is to be appreciated that by adjusting the screw 31 the overall length of the latch member 8 may be adjusted, and thus the sloping face 28 provided on the detent member 27 can be selectively positioned, this being part of the latch member that contacts the frame in which the door or panel on which the latch is fitted is received. Of course, the sloping portion may contact a striker-plate or the like.

If the latch is moved to the latching position, by rotating the knob appropriately, the detent member 27 will be moved towards the latching position and the sloping cam portion will engage the frame or striker plate. If the detent member 27 experiences any resistance to further movement towards the latching position, the springs 32, 33 will compress, and thus the detent member will not be positively driven to the latching position but will be spring biassed towards the latching position.

On the assumption that the springs 32, 33 have a substantially linear characteristic, the actual force applied by the detent member 27 against the frame or striker plate does not depend upon the precise final position of the detent member, but instead is dependent upon the force applied by the springs (F) and sine where - is the angle of inclination of the sloping face 28. Thus the latch may be used to apply a constant latching pressure, regardless of the precise eventual position of the detent member 27 with regard to the frame or striker plate engaged thereby, and also regardless of the initial precise relative positioning of the detent member 27 and the frame or striker plate.

In a modified embodiment of the invention, particularly for use on relatively narrow panels, the knob is not provided, and the latch is actuated by utilising an appropriately shaped drive key to engage the central recess provided in the rotating cam. In such an embodiment the recess may have a peculiar configuration so that only personnel having an appropriate drive key may actuate the latch.

The detent member may be made of an electrically conducting material, in which case the latch may provide an electrical current path from the door or panel on which the latch is mounted (assuming the door or panel to be made of an electrically conducting material) through the housing, through the detent member to the frame or striker plate (again assuming to be of an electrically conducting material) and thus the latch may be used in a housing or the like which is to have the properties of a Faraday Cage.

It is envisaged that most of the components of the described latch will be fabricated from stainless steel, but the latch assembly may be fabricated from members made from a material such as nylatrons or nylon 66 in which molybdenum sulphide has been incorporated to make the component electrically conductive.

Referring now to Fig. 8 of the accompanying drawings a further embodiment of the latch in accordance with the invention comprises a housing 40. The housing 40 is in the form of an inverted "U" sectioned channel portion 41, having outwardly extending flanges 42, 43 formed at the free ends of the arms of the "U" sectioned channel 41. The flanges are provided with screw holes 44 to enable the housing to be mounted in position.

At one end the "U" section channel is enlarged 45 so that the channel has a greater depth than over the rest of the length of the channel. At a position intermediate the flanges 42, 43 the side walls of the channel 41 are fore-shortened, thus providing a recess 46. At the other end, the channel is closed by a sloping end plate 47 provided with an aperture 48 therein.

A latch assembly is provided adapted to be slidingly received within the "U" section channel 41. The latch assembly is constituted by two rigid components in the form an inner or drive component 49 and a detent component 50.

The inner or drive component 49 is of generally cuboid structure. Mounted on the undersurface of the drive component 4a is a metal plate 51 which carries a downwardly extending internally threaded boss 52 which has a roller 53 mounted thereon by means of a screw 54 and a cooperating washer 55, the screw engaging the threaded boss 52. The plate 51 may be mounted on the drive or inner component 49 by means of screws or the like. The drive or inner component 49 is additionally provided with a through going bore 56 extending axially through the component. The bore 56 has an enlarged diameter portion 57 at the end adjacent the roller 53 and a section 58 of lesser diameter at the end of the drive component 49 which is adjacent the detent component 50.

The detent component 50 is of a "S"-like configuration. The detent component 50 thus comprises a first cuboid portion 59 adapted to be located under one end of the inner or drive component 49, this being connected to a vertically outstanding portion 60 provided with a threaded bore 61 therein which in turn supports a detent portion 62 which extends away from the drive component 26. The undersurface 63 of the portion 62 slopes.

The two described components are held together by means of a screw 54 which is adapted to be inserted in the bore 56. The head of the screw 64 is received within the large diameter portion 57, whereas the screw threaded portion of the screw passes through the lesser diameter portion 58 of the bore 56, through the coils of a helical compression spring 65 and into the screw threaded bore 61 formed in the detent member 51. The ends of the spring 65 are received in recesses formed in the drive component 49 and the detent component 50. The screw may be tightened so that the detent component 50 is positioned appropriately with regard to the drive component 49, but the detent component is biassed away from the drive component 49 by means of the helical compression spring 65. Thus the detent component may move in towards the drive member 49 against the bias imparted by the spring 65.

The described latch assembly is slidably received within the housing 40, with the detent portion 62 being received in the enlarged portion 45 of the channel. The roller 53 is then exposed in the cut away portion 46 of the channel between the flanges 42 and 43.

The housing 40 may then be secured, by means of screws or the like, to a panel or door 66. The housing will, in the ordinary course of events, be located adjacent another panel or the like 67 which is to be engaged by the detent 62 when the described latch is in the latching position. The latch may be actuated by means of a linkage engaging the roller 53 serving to drive the latch assembly in to and out of the latching position.

It will be understood that, as in the first described embodiment, as the detent component 50 is moved towards the latching position the sloping undersurface 63 of the detent member will engage the frame or component 67, and if the detent component 50 experiences any resistance to further movement towards the latching position the spring 65 will compress. Thus the detent component is not positively driven to the latching position but is spring biased towards the latching position.

Thus the latch applies a constant latching pressure which is dependent upon the force supplied by the spring and the angle of inclination of the face 63.

As in the first described embodiment the detent member may be made of an electrically conducting material, such as nylon incorporating the molybdenum di-sulphide, and the housing may be made of stainless or any other appropriate material.

A plurality of the latches may be driven simultaneously by a single drive linkage engaging the rollers of the latches. The latches will all exert an identical latching pressure.

Claims (24)

1. A latch for use in retaining a door or panel in a closed condition within a frame or the like, said latch comprising a housing, the housing being adapted to be mounted securely in position, the housing containing a slidable latch assembly and incorporating means for driving the assembly from a retracted position to an extended position and vice versa, the latch assembly comprising two members which are connected together but which are movable relative to each other, and which are resiliently biassed apart, the first of said members engaging said driving means and the second of said members projecting from the housing.

2. A latch according to claim 1, wherein the first member of the latch assembly has a through-going bore therein, and the second member of the latch assembly has a screwthreaded bore co-aligned with the said bore in the first member, a screw having a head portion engaging the first member passing through the bore in the first member and being screw threadedly engaged with said screw threaded bore to connect the members together.

3. A latch according to claim 1 or claim 2, wherein the first and second members of the latch assembly are biassed apart by means of coiled compression spring means located between the members, opposed ends of the compression spring means engaging said two members respectively.

4. A latch according to claim 3, wherein two compression springs are provided, the compression springs being symmetrically located with reference to the means connecting said members, means being provided to retain the ends of said springs in predetermined positions on said members.

5. A latch according to claim 3 wherein one compression spring is provided, said spring surrounding the portion of the screw extending between the first member and the second member,

6. A latch according to any one of the preceding claims, wherein the projecting member of the latch assembly is provided with a chamfered or inclined face to engage said frame.

7. A latch assembly according to any one of the preceding claims, wherein the first member of the latch assembly is provided with a groove therein which receives a peg provided on a rotary cam member, means being provided to rotate the cam member to move said latch assembly from the retracted position to the extended position and vice versa.

8. A latch according to claim 7, wherein said rotary cam member is provided with a recess therein adapted to receive a drive rod, rotation of the drive rod causing rotation of the cam.

9. A latch according to claim 8, wherein a drive rod is provided, engaged with said rotary cam, the drive rod engaging a knob, rotation of the knob effecting rotation of the rotary cam.

10. A latch according to claim 9, wherein a screw is provided passing through a bore provided in the knob and engaging a screwthreaded bore provided in the rotary cam to retain the knob in position.

11. A latch according to claim 9 or 10, wherein a substantially cylindrical element is provided between the rotary cam and the knob to retain the knob at a spaced position from the rotary cam to facilitate use of the latch on a door or panel of substantial thickness.

12. A latch according to any one of the preceding claims, wherein the housing comprises means defining a channel in which the latch assembly is slidably mounted.

13. A latch according to claim 11, as dependent upon claim 2, wherein the housing is so designed to provide ready access to the said screw which connects the members together.

14. A latch according to any one of claims 1 to 5 wherein the housing comprises a substantially "U" section channel provided with flanges thereon by means of which the channel may be secured to a door, panel or the like.

15. A latch according to claim 14 wherein said channel is provided with a recessed portion providing access to said driving means.

16. A latch according to claim 15 wherein said driving means comprises an element protruding from the first of said members, adapted to cooperate with a drive linkage.

17. A latch according to any one of claims 14 to 16 wherein the first member comprises a drive member which is of generally cuboid form, the second member comprising a detent-carrying member having a portion abutting part of the drive member and a portion carrying a detent face.

18. A latch according to any one of the preceding claims, wherein the members constituting the latch assembly are fabricated from a plastics material which is electrically conductive.

19. A latch according to claim 18, wherein the members of the latch assembly are fabricated from nylon incorporating molybdenum di-sulphide.

20. A latch according to any one of the preceding claims, wherein the components apart from the two members of the latch assembly are fabricated primarily from stainless steel.

21. A latch substantially as herein described with reference to and as shown in Figs. 1 to 6 of the accompanying drawings.

22. A latch substantially as herein described with reference to and as shown in Fig.

7 of the accompanying drawings.

23. A latch substantially as herein described with reference to and as shown in Figs. 8 to 10 of the accompanying drawings.

24. Any novel feature or combination of features disclosed herein.