GB2228283A - Doors for glove boxes - Google Patents

Abstract

In order to carry out work inside an isolator, means is provided to introduce equipment and the work materials into the isolator, and to remove the products therefrom. To this end a hinged door (122), with its associated door frame (121), onto which the door sealingly closes, is mountable adjacent the isolator and defining the doorway (120), or aperture, thereinto, wherein the door proper is centrally and hingedly mounted onto a pressure bar (123) itself hinged (130, 131) at one end, and latchable (124) at the other, to the frame, the latch being an over-centre device hinged to the frame and co-acting with (a cam and notch surface at) the bar's free end so that, as it is operated, it first captures the bar, then forces it (and thus the door) toward the frame (to seal the aperture), and finally locks "over-centre" into place (in the notch), so securing the bar, and the door, in the closed position. The door may be one end of an air-lock. <IMAGE>

Description

Doors This invention relates to doors, and concerns in particular the construction of doors for use with isolators, In many fields of technology there is a need for work to be carried out in an environment that is safely sealed off from the rest of the world. For example, in the biological sciences it is common to work with dangerously toxic or infectious materials (such as poisons, bacteria or viruses), and it will usually be desirable to carry out this work in a fully enclosed area from which the dangerous materials cannot easily escape into, and so contaminate, the surroundings.In the pharmaceutical and electronics industries, on the other hand, it may be desirable to work on some product (such as a drug or microchip) within a scrupulously clean enclosure, so as to prevent the ambient conditions contaminating the product, Both of these situations require a volume of space to be sealed off - isolated - from its surroundings, and to meet this need technology has produced the isolator, which comes in sizes varying from that of a large C1xlxl m, or about 2.5x2.5x2.5 ft) box up to that of a small room).

In essence, an isolator is little more than a sealed, bubble-like envelope in the wall of which is both a hatch (though which articles can be passed in and out) as well as means whereby the bubble's contents can be manipulated. The envelope is naturally made of some Cpreferably transparent) material suitably resistant to whatever chemicals and other substances are likely to come into contact with it both inside and outside the isolator (typical such materials are flexible polyvinyl chloride - PVC - film or sheet, but some. isolators can be made of rigid materials such as a glass). One very successful form of isolator available today is a cuboidal "bubble" of flexible PVC suspended from an external framework that both shapes and supports the bubble.A particularly satisfactory bubble isolator is that described and claimed in the Specification of our co-pending British Patent Application No. 88/05,817.

That isolator is one having a tray-like base portion of a generally rigid physically and chemically resistant material upon which is sealing mounted around the edges thereof a tent-like canopy portion of a flexible and transparent chemically resistant material.

In order to carry out work inside an isolator it must be possible for the operator outside to get in, or to reach in, without risk of contamination to him or to the isolator's contents, and this is usually achieved with a full- or half-suit or with gloves (as in a conventional glove box). In addition, of course, means must be provided to introduce equipment and the work materials themselves into the isolator, and to remove the products therefrom. In some cases it will be acceptable to break the containment of the isolator for instance, when loading a transfer isolator with materials prior to sterilisation. In other cases, however, containment must not be breached, and some sort of "air lock" means, such as a double-door transfer port, or a lock-chamber, will be required.Clearly, where either a simple loading port or a lock-chamber is used a door is needed - that is, there is required some form of closure means capable of sealingly closing a suitable aperture in the isolator wall. One such device that has found wide use in the past is the so-called "iampot cover" port. Here, a short tube is mounted in the wall of the isolator, and a simple plastics cap is placed over it (to seal the aperture)~, and suitably secured thereto (commonly by an elastic band and a metal circlip). This is simple and cheap, but it is also cumbersome and time-consuming to operate - the more so in the case of a lock-chamber, since the cap, band and circlip must be fitted inside the isolator, where access is limited.What is required is a hinged door with an easy-to-operate latch allowing more or less instant access, and the invention proposes just such an "instant access door" (lAD). More specifically, the invention suggests a hinged door (and its associated door frame, onto which the door sealingly closes, mountable adjacent the isolator and defining the doorway, or aperture, thereinto) wherein the door proper is centrally and hingedly mounted onto a pressure bar itself hinged at one end, and latchable at the other, to the frame, the latch being an over-centre device hinged to the frame and co-acting with (a cam and notch surface at) the bar's free end so that, as it is operated, it first captures the bar, then forces it (and thus the door) toward the frame (to seal the aperture), and finally locks "over-centre" into place (in the notch), so securing the bar, and the door, in the closed position.

In one aspect, therefore, the invention provides closure apparatus primarily for use with an isolator, which apparatus comprises: an apertured frame defining a doorway; a pressure bar extending across the aperture and hingedly mounted at one end to the frame; a door, adapted sealingly to close the aperture in the frame. pivotally mounted at its centre halfway along the length of the bar; and an over-centre latch mounted on the frame diametrically opposite the bar hinge, which latch in use latches the bar towards the frame and thus presses the door to the frame to close the aperture.

The closure apparatus of the invention is primarily intended for use as an instant access door to be utilized with an isolator (and for the most part is described as such hereinafter), though in fact it could be employed as a door into or out of any space that needs some means of closing it off simply and quickly from some neighbouring space. Where, however, it is used with an isolator, then the isolator may be of any variety, especially one of those the subject of our aforementioned Application No: 88/05,817.

The inventive closure apparatus includes an apertured frame. This frame will be mountable on the isolator (or other device) with which the apparatus is to be used so as to constitute a doorway thereinto.

Naturally, the aperture may be of any appropriate shape and size, but for most isolators a suitable shape is circular, a convenient size being around 38 cm (15 in) in diameter (such a size is generally satisfactory for the insertion of material and equipment into, and their withdrawal from, the isolator). The frame in which the aperture is formed may itself take any form suitable; for most isolators - say, those of the type described in our aforementioned Application - which themselves have an external tubular steel framework, a similar frame, of matching tubular steel, will suffice. Indeed, it will probably be possible to build the two frames - the isolator framework and the closure means frame - as a single, integral part.That part of the closure means frame that the door seals against, however, is most preferably a flat apertured plate (defining the doorway and the sealing surface) mounted on å short sxiallyaligned tube (defining the "depth" of the doorway) like an inwardly-extending flange. It is this tube that "pierces" the isolator canopy, constituting a passageway thereinto, and the canopy may be sealingly joined therearound in any convenient way - and usually by means of an elastic retaining ring with a circlip clamp therearound. Such a flanged tube arrangement, built integrally into an isolator framework, is discussed hereinafter with reference to the accompanying Drawings.

Extending across the aperture, and carrying the door per se, is the pressure bar by which the door is forced into sealing engagement with the aperture's surround. This bar, conveniently made of some "springy" material - an aluminium alloy bar, of about 25 mm (1 in) square cross-section has proven eminently satisfactory is hingedly mounted at one end onto the apertured frame (and preferably onto the flange defining the sealing surface), conveniently by a hinge mechanism that stands proud of the frame itself (so that, when the door is closed, the bar is parallel to but spaced from the frame's aperture, with the door trapped in the space therebetween). In use, the forces on the hinge mechanism are high, so it should be one of some substance.

Mounted centrally of (halfway along) the bar is the door. The door may be of any shape and size, but will most conveniently - naturally - be such as to match the aperture. Equally, the door may be of any suitable material, including a sheet metal such as steel, but is most preferably transparent (allowing the operator to see through it into the isolator), and may with advantage be made of a clear, preferably water-white material such as a glass or some synthetic resin - for example, a polyacrylic such as PERSPEX, or a polycarbonate such as MACROLON, that is fairly light and has some limited flexibility. Indeed, a 12 mm (0.5 in) thick door of the latter material has proven very satisfactory.

The door is adapted to close the aperture, and to close it sealingly. Like most doors it will conveniently close in such a fashion as around its periphery to abut face-to-face the relevant (door-side) surface of the aperture-defining frame, and this can be ensured to be a sealing closure by placing a suitable sealing gasket on the frame surface or, and preferably, on the relevant (frame-side) door surface. The gasket may be an Wring made of a silicone or a nit rile rubber, but a particularly preferred material is neoprene foam.

The gasket is mounted within a shallow groove in the abutting surface of the door.

The door is mounted centrally on the pressure bar both centrally of the bar and centrally of the door.

Thus, the mounting means joining the door to the bar is central of the door itself; the entire closing force applied to the door by the bar is thus applied centrally, and, assisted by the slight flexibility of the door, "spreads out" through the door to become a somewhat lesser force applied evenly over each unit length of the door's periphery (strictly, this peripheral force will be even only if the distance from the central application point to the periphery is the same all the way round - in other words, if the door is circular).The door mounting means very preferably allows the door just to "float" thereon - that is to say, very slightly to pivot relative to the bar in two orthogonal directions both normal to the plane of the door - so that it can accommodate small deviations in the parallelism of the plane of the aperture and the "plane" of the pressure bar as and when the door is closed. Without this small "float" ability, giving the door the capacity to move slightly on its mounting, as the door was closed the bar-hinge side would necessarily contact the frame first, and the build-up of an off-centre force as closure continued might cause some part of the whole apparatus (but particularly the door itself) to break.As discussed hereinafter with reference to the accompanying Drawings, a convenient way to achieve this limited float is to pivot the door on the bar via a pivot pin passing through a pivot block (the preferred embodiment has a pin passing through the bar and extending into two pivot blocks one on either side thereof to which the door is rigidly secured) wherein the pin is a loose fit in the block, so that not only can normal pivoting occur around the pin's axis but in addition the "looseness" enables the block, and thus the door, to move back and forth in a direction normal to the axis.

The door may, of course, be mounted on either side of the frame defining the aperture - that is, it may be an "outside" door, mounted on the outside of some device (such as an isolator) and opening outwardly, or it may be an "inside" door, mounted on the inside and opening inwardly. Indeed, it may be desirable for some types of isolator, say, to have two doors - one outside, one inside - spaced apart by a relatively deep aperturedefining frame, the whole forming an airlock. In such a case, the two doors may be interlocked (by mechanical, electrical or electronic means) so that only one door can be open at a time, and/or to provide a delay between the closure of one and the opening of the other.

The pressure bar is hinged to the frame at one end and latched to the frame at the other. The latch is an over-centre latch itself hingedly mounted on the frame (preferably on the flange, as in the bar hinge). An over-centre latch is one that passes through a central metastable position between two stable positions; in the present context the term means a latch that is movable from an unlatched stable position to a latched stable position via a semi-latched metastable position at which it can be sent in either direction by minimal force. To allow this latch to co-act properly with the bar, the end length of the bar has its outer surface profiled into a cam surface with a locking recess into which the latch slips when past its centre point.Moreover, to enable the latch to move smoothly over this cam surface and into the recess, the latch advantageously incorporates a small roller that bears thereon, and that rolls thereover. An example of such an arrangement is discussed hereinafter with reference to the accompanying Drawings.

The latch mechanism may be of any suitable material, typically aluminium or an alloy thereof, like the pressure bar.

An embodiment of the invention is now described, though only by way of illustration, with reference to the accompanying diagrammatic Drawings in which Figure 1 shows a perspective view from above and one end of a glove box isolator of the invention; Figure 2 is a perspective part view from outside of a closure apparatus of the invention in place in an isolator; Figure 3 is a front elevation view of the closure apparatus of Figure 2; Figure 4 is a part sectional (on the line IV-IV in Figure 3), part plan view of the apparatus of Figure 2; and Figure 5 is a composite "plan" view showing the application of the over-centre latch to close the door of the apparatus of Figure 2.

The isolator (generally 10) shown in the Drawings has a rigid tray-like base part (11) onto which is sealingly mounted a transparent flexible tent-like canopy part (12). The canopy 12 is supported in place above the tray via loops (52) by a framework (50) the crossbars (51) of which also support the tray 11. The tray 11 is oblong, and has a floor (13), a perimeter wall (14), and a lip (15). The canopy 12 is cuboidal (matching the tray 11 dimensions), and is sealingly mounted on the tray by having its open end edge (not shown) folded around the tray's lip 15 and held in place by an extended U-channel trim-strip clip (not shown) that runs all the way round the base.

The glove box has the usual glove pair (generally 19) and hatch and hatchway (20). It is this hatch/way that is the aperture closable by the closure means of the invention (not shown in Figure 1), as is now described.

As can be seen from Figures 2 to 4, the closure apparatus - the instant access door (lAD) - consists of four main elements: the frame (121) defining the aperture (120); the door (122) hingedly mounted on the pressure bar (123); and the latch mechanism (124). The frame 121 is primarily a short tube (125: in this embodiment made from polished stainless steel) mounted on the isolator support frame (50) and sealed to the isolator canopy (12: not shown in Figure 2) with a combination (126) of elastic ring and circlip. In the simple IAD there is a inward flange (127) fixed at one end of the tube 125, reducing the tube diameter slightly and providing means to mount and seal the door 122. In the case of a lock-chamber, such a flange 123 is provided at each end of the tube.

The door 122 is a circular piece of polycarbonate plastic of the same diameter (roughly) as the outside of the frame tube 125. A groove (128: see Figure 4) is machined into the periphery of the inside of the door, to accept a sealing wring gasket (129) so that when the door is pressed against the flange 127 the aperture 120 is closed in a gas-tight fashion. In this embodiment the seal is neoprene foam of circular cross-section; it has considerable flexibility, and will seal despite irregularities in the face of the frame, thus avoiding costly surface machining of the frame.

The door 122 is mounted at its centre on a horizontal hinged pressure bar 123. This bar is at one end hinged to the flange 127 by the combination pivot pin < 130) and double block (131), and is pulled against the flange by the latch mechanism 124. Thus, the door 122 is pressed at its centre only, against the flange 127, so ensuring an even sealing pressure around the seal 129 and the edge of the door, and in this way avoiding the need for a series of edge-clips or -clamps, or other edge-pressing devices.

The door itself is mounted on the bar 123 by another combination of pivot pin (132: see Figures 3 and 4) and double block (133: not shown in Figure 4), and the mounting is such as to allow the door to "float" both around the pin and normal thereto (on an axis parallel to the bar 123). In this way the door can move to accommodate the flange 127 as it is closed thereon.

As will be apparent, with the door 122 mounted centrally of the bar 123, and the bar hinged at one end and latched at the other, a mechanical advantage of two to one is applied by the bar to the door in pressing it to the flange.

The latch mechanism 124 (best seen in Figures 4 and 5) is an over-centre lever device which pulls the pressure bar 123 towards the frame and holds it there, maintaining the door and its seal 129 in intimate contact with the flange 127. As can be seen from Figure 5, the latch incorporates in its handle (134) a roller to35) which rides up a ramp (136 - an inclined cam surface) - and thence into a suitable notch or recess (137) machined in the end of the bar. The latch handle applies a mechanical advantage of about ten to one on the bar, so that the overall advantage between the latch handle 134 and the centre of the door 122 is about twenty to one. A force of 5 kg (11 lb) at the latch handle therefore applies one of 10.0 kg (220 lb) to the door. The roller 135 and ramp 136 are arranged in such a way as to make the action easy for one-handed operation, and the latch handle 134 is shaped to "fold" flat against the bar 123 in the closed position (and is thus less liable to accidental opening) - though a safety pin may be provided for added security.

Claims (13)

1. Closure apparatus primarily for use with an isolator, which apparatus comprises: an apertured frame defining a doorway; a pressure bar extending across the aperture and hingedly mounted at one end to the frame; a door, adapted sealingly to close the aperture in the frame. pivotally mounted at its centre halfway along the length of the bar; and an over-centre latch mounted on the frame diametrically opposite the bar hinge, which latch in use latches the bar towards the frame and thus presses the door to the frame to close the aperture.

2. Apparatus as claimed in Claim 1, wherein the aperture, and thus the door, is circular.

3. Apparatus as claimed in either of the preceding Claims, wherein that part of the closure means frame that the door seals against is a flat apertured plate (defining the doorway and the sealing surface) mounted on a short axially-aligned tube (defining the "depth" of the doorway) like an inwardly-extending flange.

4. Apparatus as claimed in any of the preceding Claims, wherein the pressure bar by which the door is forced into sealing engagement with the aperture's surround is made of some "springy" material and is hingedly mounted at one end onto the apertured frame by a hinge mechanism that stands proud of the frame itself.

5. Apparatus as claimed in any of the preceding Claims, wherein the door is transparent, being made of a clear, water-white material.

6. Apparatus as claimed in any of the preceding Claims, wherein the door closes in such a fashion as around its periphery to abut face-to-face the relevant < door-side) surface of the aperture-defining frame, and this is ensured to be a sealing closure by placing a suitable sealing gasket on the frame surface or on the relevant < frame-side) door surface.

7. Apparatus as claimed in Claim 6, wherein the gasket is an-Oring made of neoprene foam

8. Apparatus as claimed in any of the preceding Claims, wherein the door mounting means allows the door just to "float" thereon - that is to say, very slightly to pivot relative to the bar in two orthogonal directions both normal to the plane of the door - so that it can accommodate small deviations in the parallelism of the plane of the aperture and the "plane" of the pressure bar as and when the door is closed.

9. Apparatus as claimed in Claim 8, wherein this limited float is achieved by pivoting the door on the bar via a pivot pin passing through a pivot block wherein the pin is a loose fit in the block, c; that not only can normal pivotirig tlg occur around the pin's axis but in addition the "looseness" enables the block, and thus the door, to move back and forth in a direction normal to the axis.

10. Apparatus as claimed in any of the preceding Claims, wherein there is a door mounted on either side of the frame defining the aperture, the whole forming an airlock, and the two doors are interlocked so that only one door can be open at a time, and/or to provide a delay between the closure of one and the opening of the other.

11. Apparatus as claimed in any of the preceding Claims, wherein to enable the latching of the pressure bar to the frame by over-centre latch means the end length of the bar has its outer surface profiled into a cam surface with a locking recess into which the latch slips when past its centre point, and to enable the latch to move smoothly over this cam surface and into the recess, the latch incorporates a small roller that bears thereon, and that rolls thereover.

12. Apparatus as claimed in any of the preceding Claims and substantially as described hereinbefore.

13. An isolator using closure apparatus as claimed in any of the preceding Claims.