GB2168744A - Releasable fastening - Google Patents

Abstract

The fastening is mounted on a panel or door 41 and has a bolt assembly 26, 33, pivoted at 25 and comprising a portion 33 movable relative to the remainder of the bolt, and biassed by a leaf spring 37 to act on the frame 44 to urge the door 41 against a seal 46. The bolt has a lug 27 engageable with an abutment 19 on a resiliently biased actuating lever 17 to hold the bolt in the closed position. <IMAGE>

Description

SPECIFICATION Improvements in or relating to a latch The present invention relates to a latch and, more particularly, the present invention relates to a latch of the type that can be considered to be a flush latch.

Flush latches have been in use for some time, and two embodiments of prior proposed flush latches are described in British Patent Specifications Nos.

614,425 and 724,933.

Flush latches may be used to hold doors or inspection hatches in position and normally include a pivotal member having a detent that can engage against a rear surface surrounding an aperture in a wall or outer skin of a casing or aircraft to hold an inspection panel or the like in position.

There is now a requirement for latches to be used in connection with housings for electronic apparatus. These housings must not permit the leakage of electro-magnetic radiation either into or out of the housing, and thus it is important that any removable panel can be replaced in position in such a way that the panel is substantially electrically continuous with the remainder of the housing. Thus a good electrically conductive seal must be established completely around the periphery of each inspection panel when the panel is in the closed condition.

It has been proposed to utilise resilient sealing means to surround an inspection hatch which is closed by an inspection panel held in position with flush latches of the prior-art type, but it has been found that these resilient seals are under compression for significant period of time, since the inspection panels are usually in the closed condition, and then tend to lose their resilience whilst in the compressed condition. Then, after the inspection hatch has been removed and replaced, the resultant seal may not be adequate.

According to this invention there is provided a latch, said latch comprising means to mount the latch on a planar panel, door or the like, the latch having a movable element movable between an engagement position and a release position, and releasable means to retain said member in the engagement position, the said movable element having a portion adapted to engage part of the structure in which the door or panel is or is to be mounted, the said portion being resiliently movable in a direction perpendicular to the plane of the panel against a biassing force.

Preferably said element consists of two parts mounted on a common pivotal axis, a first part having means adapted to engage a catch on said releasable means to retain said first part in a predetermined locking position, the second part being pivotal relative to the first part but being biassed towards a predetermined position by means of a resilient element, the said portion being constituted by said second part.

Advantageously the resilient element comprises a leaf spring connected to the first part and extending over or adjacent part of the second part.

Conveniently the degree of pivotal movement between the second part and the first part is limited.

In one embodiment one of said parts has two bifurcated portions which surround and embrace a corresponding portion of the other part, the said bifurcated portions and the surrounded portion each being provided with a bore therethrough accommodating a pivot pin on which the said member is pivotally mounted, said portions further being provided with a pin carried by one part extending through an aperture or apertures in said portion or portions on the other part to limit the degree of pivotal movement between the two parts.

Preferably the movable element is spring biassed towards the release position but is retained in the engagement position by said releasable means.

Conveniently the said releasable means comprise a pivoted member biassed towards a position in which a catch thereon engages an abutment on the movable element to retain the movable element in the engagement position, the said pivotal member being movable against the bias to release the catch.

Preferably the elements of the latch are pivotally supported in a saddle-sectioned support member.

In orderthat the present invention may be more readiiy understood, and so that further features thereof may be appreciated, the invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is an exploded view of a latch in accordance with the invention illustrating the component parts thereof; Figure 2 is a perspective view showing the latch mounted on an inspection panel about to be mounted in position in the wall of a housing; Figure 3 is a cross-sectional view through the latch when in the closed position; and Figure 4 is a cross-sectional view corresponding to Figure 3 showing the latch in the open position, but before the panel has been removed from the opening in which it is mounted.

A latch in accordance with the present invention comprises a saddle-sectioned support member 1 which consists of two horizontal flanges 2,3 provided with apertures therein to enable the flanges to be secured to an inspection panel or the like, the flanges being connected by an inverted "U" section channel portion 5. The channel portion 5 has two upstanding side walls 6,7 interconnected by a horizontal upper region 8. The upstanding side walls are each provided with a plurality of apertures 9.

The apertures in the two side walls are aligned with each other to receive pivot pins and the like, as will be explained.

Two aligned apertures 9 adjacent the rear of the described catch support a first transverse rod 10 around which is mounted a spring 11, the spring having protruding portions 12 which can engage the undersurface of the horizontal top part 8 of the inverted "U" section channel portion 5 and downwardly extending portions 13 which can exert a downward rotational force in the direction of the arrow 14.

A second transverse rod 15, which again is located in appropriate apertures 9 and side walls 6 and 7, passes through a bore 16 provided in part of a release member 17 so that the release member is pivotally mounted in position. The release member 17 comprises a horizontal portion 18 terminating at its front end in a catch 19. The downwardly extending portion 13 of the spring 11 engages the upper surface of the horizontal portion of the release member and exerts said downward rotational force thereon.

A third transverse rod 20 is provided which is located somewhat closer towards the front of the described catch. The transverse rod 20 again passes through co-aligned apertures 9 in side walls 6 and 7 and supports a spring 21 which has upwardly directed portions 22 adapted to engage the undersurface of the top part 8 of the inverted "U" channel section 5. The spring 21 has a downwardly inclined curved portion 23 which is adapted to cooperate and spring bias a detent assembly 24 which is pivotally supported in the channel on a pivot pin 25 which is accommodated in appropriate apertures 9 formed in the side wall 6,7 of the inverted "U" section channel portion 5 of the catch.

The portion 23 of the spring engages a portion of the detent assembly which is to the rear of the pivot pin 25, thus imparting an anti-clockwise rotational force to the detent assembly as shown in Figure 1.

The detent assembly 24 comprises a latch member 26 having an abutment 27 adapted to cooperate with the catch 19 formed on the release member 17 in a manner as will be described hereinafter. The latch member 26 terminates, at its forward end, with a centrally located forwardly directed projection 28 which defines a transverse bore 29 therethrough to accommodate the pivot pin 25 and which also defines an oval slot 30 therethrough. The portion 28 has a lesser width than the width of the rest of the latch member 26 and is located between two bifurcated portions 31,32 of a detent member 33. The bifurcated portions 31,32 are provided with transverse bores 34 which can be aligned in the bore 29 to slidingly receive the pivot pin 25 which is then mounted in position in the channel.It will be appreciated that the latch member 26 and the detent member 33 can then both pivot about the pivot pin 25.

A retaining pin 35 is passed through two coaligned apertures 36 formed in the bifurcated portions 31,32 and through the oval slot 30 in the forwarded extending projection 28 provided on the latch member 26. The presence of the pin 35 serves to restrict the degree of pivotal movement between the latch member 26 and the detent member 33.

A leaf spring 37, which is connected by means of rivets 38 to the top surface 39 of the latch member 26, overlies the upper surface of the latch member 26 and the upper surface of the detent member 33.

The leaf spring 37 tends to bias the detent member 33 downwardly (that is to say clockwise in the orientation of Figure 1) and the arrangement is such that a forward lip 40 of the detent member 33 can be iifted upwardly, pivoting the detent member about the pivot pin 25, against the bias exerted by the leaf spring 37. During such pivotal movement of the detent member the pin 35 moves relative to the oval slot 30.

When the various components described above have been assembled the spring 11 tends to bias the release member 17 to rotate in an anti-clockwise direction (as considered in your orientation of Figure 1) and the spring 21 also serves to bias the detent assembly 24 to rotate in an anti-clockwise direction (as considered in your orientation of Figure 1) about the pivot pin 25.

When the catch has been assembled the catch may be mounted on a planar door or panel 41 which is to be mounted in position in a correspondingly shaped hole in a panel, orwall of a housing orthe like. The panel 41 is provided with a protruding lip 42 on the undersurface thereof and the catch is mounted on the top surface of the panel. An aperture is formed in the panel to provide access to the operating components of the catch. The panel 41 is intended to be located in an aperture 43 formed in a wall 44. The aperture 43 is surrounded by a recess 45 on the outer side of the wall 44 and provided within the recess is a cylindrical resilient sealing member 46 which may be made of an electrically conductive resilient material.

When the panel 41 has been fully mounted in position the components of the catch will occupy the position illustrated in Figure 3 with the lip 42 engaging the seal 45 and the lip 40 of the catch engaging the inner surface of the wall 44.

As can be seen the release member 17 is in such a position that the catch 19 formed thereon is engaged under the abutment 27 formed on the latch member 26. The spring 11 is serving to bias the release member 17 firmly into this position to prevent inadvertent release of the catch.

The spring 21 is also compressed applying a force to the detent assembly tending to rotate the detent assembly in an anti-clockwise direction about the pivot axis 25 when considered in the orientation shown in Figure 3. However, the detent assembly cannot rotate ahout that axis by virtue of engagement between the catch 19 and the catch cooperating detent 27.

The forward lip 40 of the abutment member 33 is in engagement with inner surface of the wall 44 and is serving to bias the panel 41 into engagement with the sealing means 46. In actual fact the pressure exerted by the lip 40 is such that the leaf spring 37 has been deflected, and the detent member 33 has moved pivotally relative to the latch member 26.

The lip 40 has thus moved in a direction perpendicular to the plane of the panel against a biassing force. It will thus be appreciated that the portion of the detent member that actually engages the wall 44 is effectively resilient. As can be seen the pin 35 has moved along the oval slot 30.

When it is desired to release the catch pressure is applied to the release member 17 in the direction shown by the arrow 47. The release member then moves in a clockwise direction against the bias of the spring 11, but after the release member has moved by only a short distance the catch 19 is released from the catch cooperating detent 27 and the detent assembly can then rotate about the axis of the pivot pin 25 under the influence of the spring 21.The components then adoptthe position illustrated in Figure 4 and it can be seen that the panel can then readily be removed from the aperture in the wall 44.

It will be appreciated that catches in accordance with the invention may be utilised to support a hinged or other inspection panel in position in a wall. When a catch has been used to mount the panel in position under normal circumstances the lip 40 of the detent will be in such a position that the spring 37 is deflected. It will be appreciated that even if the seal 46 is resilient and tends to loose its resilience with time, because of the resilient nature of the detent 40, a continued pressure will be applied to the seal, thus ensuring that an adequate sealing characteristic is obtained.

The nature of the leaf spring is such that the pressure applied by the leaf spring is substantially linear over the permitted deflection of the detent member relative to the catch cooperation member.

It is to be appreciated that various embodiments may be designed incorporating leaf springs of different strengths, and such embodiments will each have different characteristics.

Claims (11)

1. A latch, said latch comprising means to mount the latch on a planar panel, door or the like, the latch having a movable element movable between an engagement position and a release position, and releasable means to retain said member in the engagement position, the said movable element having a portion adapted to engage part of the structure in which the door or panel is or is to be mounted, the said portion being resiliently movable in a direction perpendicular to the plane of the panel against a biassing force.

2. A latch according to claim 1, wherein said element consists of two parts mounted on a common pivotal axis, a first part having means adapted to engage a catch on said releasable means to retain said first part in a predetermined locking position, the second part being pivotal relative to the first part but being biassed towards a predetermined position by means of a resilient element, the said portion being constituted by said second part.

3. A latch according to claim 2, wherein the resilient element comprises a leaf spring connected to the first part and extending over or adjacent part of the second part.

4. A latch according to any one of claims 2 to 3, wherein the degree of pivotal movement between the second part and the first part is limited.

5. A latch according to claim 4, wherein one of said parts has two bifurcated portions which surround and embrace a corresponding portion of the other part, the said bifurcated portions and the surrounded portion each being provided with a bore therethrough accommodating a pivot pin on which the said member is pivotally mounted, said portions further being provided with a pin carried by one part extending through an aperture or apertures in said portion or portions on the other part to limit the degree of pivotal movement between the two parts.

6. A latch according to any one of the preceding claims wherein the movable element is spring biassed towards the release position but is retained in the engagement position by said releasable means.

7. A latch according to any one of the preceding claims, wherein the said releasable means comprise a pivoted member biassed towards a position in which a catch thereon engages an abutment on the movable element to retain the movable element in the engagement position, the said pivotal member being movable against the bias to release the catch.

8. A latch according to any one of the preceding claims wherein the elements of the latch are pivotally supported in a saddle-sectioned support member.

9. A latch substantially as herein described with reference to and as shown in the accompanying drawings.

10. A panel or door whenever provided with a latch according to any one of the preceding claims.

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