I A RACK FOR ANIMAL CAGES FIELD OF INVENTION [001] The present invention relates to a rack for cages and caging systems for laboratory animals and more particularly to a rack for cages and rack systems for housing a variety of rodent types. BACKGROUND OF THE ]INVENTION [002] Conventional cage and rack systems typically includes a rack system having a plurality of shelves from which a series of box-like cages are suspended, or upon which such cages are mounted. [003] One of the main disadvantages of conventional systems is that air quality and air temperature in a particular cage can often depend on a variety of factors including the number of cages mounted to the rack, the number of animals in the particular cage, the level of their activity. [004] Any references herein to known prior art does not, unless the contrary indication appears, constitute an admission that such prior art is commonly known by those skilled in the art to which the invention relates, at the priority date of this application. SUMMARY OF THE INVENTION [005) The present invention provides a rack for animal cages including a shelf means for supporting a plurality of animal cages, said rack including a chimney member, said rack including a pivoting flap means associated with said chimney member which is adapted to be moved into an open condition by a cage to be located on said shelf means. [006] The shelf means can be integral with the chimney member. [007] The pivoting flap means can be urged to a closed condition when not engaged by a cage [008] The shelf means can be able to support a cage on opposed sides of said rack BRIEF DESCRIPTION OF THE DRAWINGS [009] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 2 [010] Fig. I is a front elevation of an animal caging system according to the present [011] invention; [012] Fig. 2 is an end elevation of the animal caging system of Fig. 1, as seen when looking toward the right end of the caging system as shown in Fig. 1; [013] Fig. 3 is a fragmentary end elevation similar to Fig. 2 but showing in greater detail a pair of adjacent cages as they appear when installed in the caging system; [014] Fig. 4 is a perspective view of the caging system of Fig. 1; [015] Fig. 5 is a fragmentary perspective view similar to Fig. 4 but showing in greater detail a pair of adjacent rack modules as they appear when assembled in the rack illustrated in Fig.1; [016] Fig. 6 is a front elevation of the rack module of Fig. 5; [017] Fig. 7 is an end view of the rack module of Fig.5; [018] Fig. 8 is a top view of the rack module of Fig. 5; [019] Fig. 9 is a perspective view of the rack module of Fig. 5; [020] Fig. 9a is a schematic view of a row of assembled rack modules of Fig. 5; [021] Fig. 10 is a perspective top view of a rack shelf of the animal caging system of Fig. 1; [022] Fig. 11 is a perspective bottom view of the rack shelf of Fig. 10; [023] Fig. 12 is a front elevation view of the rack shelf of Fig. 10; [024] Fig. 13 is a top view of the rack shelf of Fig. 10; [025] Fig. 14 is an end view of the rack shelf of Fig. 10; [026] Fig. 15 is a perspective bottom view of a flap valve of the animal caging system of Fig. 1; [027] Fig. 16 is a bottom view of the flap valve of Fig. 15; [028] Fig. 17 is a front elevation view of the flap valve of Fig. 15; [029] Fig. 18 is an end view of the flap valve of Fig. 15; [030] Fig. 19 is a perspective top view of a cage of the animal caging system of Fig. 1; [031] Fig. 20 is a front elevation of the cage of Fig. 19; 3 [032] Fig. 21 is a top view of the cage of Fig. 19; [033] Fig. 22 is an end view of the cage of Fig. 19; [034] Fig. 23 is a perspective top view of a cage body of the cage of Fig. 19; [035] Fig. 24 is a front elevation of the cage body of Fig. 23; [036] Fig. 25 is a top view of the cage body of Fig. 23; [037] Fig. 26 is an end view of the cage body of Fig.23; [038] Fig. 27 is a perspective top view of a cage lid of the cage of Fig. 19; [039] Fig. 28 is a front elevation of the cage lid of Fig. 27; [040] Fig. 29 is a top view of the cage lid of Fig. 27; [041] Fig. 30 is an end view of the cage lid of Fig.27; [042] Fig. 31 is an exploded view of a filter arrangement of an air intake port of the cage of Fig. 19; [043] Fig. 32 is a perspective top view of a feeder of the cage of Fig. 19; [044] Fig. 33 is a front elevation of the feeder of Fig. 32; [045] Fig. 34 is a top view of the feeder of Fig. 32; [046] Fig. 35 is an end view of the feeder of Fig.32; [047] Fig. 36 is an exploded view of a filter arrangement in an air exhaust port of the cage of Fig. 19; [048] Fig. 37 is perspective top view of a rack cover of the animal caging system of Fig. 1; [049] Fig. 38 is an end view of the rack cover of Fig. 37; [050] Fig. 39 is a top view of the rack cover of Fig. 37; [051] Fig. 40 is a front elevation view of a modified form of a rack module; [052] Fig. 41 is a an end view of the rack module of Fig. 40; [053] Fig. 42 is a top view of the rack module of Fig. 40; [054] Fig. 43 is a perspective view of a rack module; and [055] Fig. 44 is a perspective view of a modified form of a flap of a flap valve. DETAILED DESCRIPTION OF THE EMBODIMENTS 4 [056] Referring now to the drawings, there is illustrated in Figs. I - 4 an animal caging system 10 embodying the present invention. The animal caging system 10 includes a rack 12 adapted to cooperate with one or more animal cages 14a, 14b, 14c, 14d, 14e, etc at spaced locations along the height and the length of the rack 12, to support the cages in a generally horizontal orientation. The rack 12 is of generally rectangular configuration and is supported on a movable platform 16 in an inverted T-like configuration. The platform 16 is provided with four conventional casters 18. [057] As best shown in Figs. 4-9, the rack 12 is of modular construction and includes a plurality of Z-shaped rack modules 20a, 20b, 20c, 20d, etc. Each module 20a is provided with a pair of generally vertical slots 22a, 22b, the slot 22a being adapted to receive a complementary projection 24a of an adjacent rack module 20d, the slot 22b being adapted to receive a complementary projection 24b of an adjacent rack module 20c to form a horizontal row 24 of rack modules 20, as shown in Fig. 1. Likewise, each rack module 20a is provided with a generally horizontal slot 26 adapted to engage a complementary upper portion of an adjacent rack module 20b to form a vertical row 28 of the rack modules 20. [058] The 'Z'-shaped module 20 can include two generally rectangular planar side members and a generally rectangular planar cross member extending therebetween to form a 'Z'-like configuration in cross section. Whilst Figs.6-9 illustrate that the cross member is connected to the side members at a right angle of 900, it will be understood by those skilled in the art any other suitable angle can be used (eg an acute angle or an obtuse angle). [059] Furthermore, the term "Z-shaped module" extends to include within its meaning 'a substantially Z-shaped module' and can therefore cover a 'Z'-shaped module wherein the cross member is connected to a portion of a side member, the portion being spaced from an end of said member. [060] The term 'substantially Z-shaped module' can also cover a rack module including non-planar and or non-rectangular members. It will be appreciated by those skilled in the art that a 'S'- shaped module can therefore be described as substantially 'Z'-shaped module. [061] Likewise, Z-shaped module can include two or more cross-members. [062] If so desired, the horizontal row 24 can include a L-shaped member 201 on the left hand side of the row 24, and an inverted L - shaped member 20r on the right hand side of the row 24, as illustrated in Fig. 9a.
5 [063] When assembled, two adjacent rack modules in a horizontal row (eg, (20c, 20a) or (20a, 20d)) form a section of a vertical air exhaust plenum 70 which withdraws air through the openings 71a, 71b. [064] As shown in Figs. 1, 2 and 37-39, the assembled vertical row 28 of the rack modules 20 is covered by a rack cover 130 sized to form a sealing connection with a pair of adjacent rack modules 20. The rack cover 130 is provided with an exhaust hole 132 and bolt holes 134a and 134b. As a result, the vertical row 28 of the rack modules 20 sandwiched between the platform 16 and the rack cover 130 can be secured to the platform 16 by a bolt 29 passing through the platform 16, the row 28 and the bolt hole 134 provided in the rack cover 130. [065] As a result of such modular construction, the rack 12 can accommodate any desirable number of the cages 14 in any desirable configuration, be it, for example, vertical or horizontal. [066] As best shown in Figs. 3 and 9, each rack module 20 is provided with a pair of rectangular tubular projections (30a, 30b) upon which rack shelves 36 are mounted. The projection 30 is sized so as to create a tension fit against the internal surfaces of the guiding projections 37a and 37b extending from the bottom surface of the rack shelf 36. To prevent vertical displacements of the rack shelves 36 relative to the rack modules 20, each rack shelf is provided with a slot 38 formed on the triangular portion 40 of the rack shelf 36. The slots 38 are adapted to receive complementary projections (34a, 34b) located on opposite sides 32a and 32b of the rack module 20. [067] As best shown in Figs. 10 and 13, the upper surface 42 of the rack shelf 36 is of generally rectangular configuration and is provided with a pair of guiding slots 44a and 44b the purpose of which will be described later in this specification. [068] Referring now to Figs. 11 and 15-18, the bottom portion 46 of the shelf 36 is provided with a transverse projection 48 against which an upper portion 50 of a bar member 52 of a flap valve 54 abuts. The lower portion 56 of the bar member 52 abuts against generally arc-shaped sections 60a and 60b formed on cut-out portions of the tubular projection 30. As a result, a flap 64 of the flap valve 54 is pivotable around the longitudinal axis X of the bar member 52 between an opening position wherein the flap 64 assumes a generally horizontal position thereby permitting air flow through the tubular projection 30b into the air plenum 70, as illustrated in Fig. 3, and a closing position (not shown) wherein a 6 portion of a generally triangular planar projection 65 extending downwards from a flap 64 is received within a slot 74 formed in the bottom portion 72b of the hollow projection 30b. [069] To prevent air flow through the projection 30b when the flap valve is in the closing position, the width W and length L of the flap member 64 are such that in its closing position the flap member 64 rests seahingly on the inner wall of the hollow projection 30b. [070] As shown in Fig. 3, when a cage 14 is placed on the shelf 36a, the flap valve 54 of the shelf 36 is in its opening position. To achieve correct positioning of a cage relative to the rack, the bottom portion of each cage 14 is provided with a pair of elongated guide members 80a and 80b adapted to be slidably received in the slots 44a, 44b formed on the upper surface of the shelf 36a. As shown in Fig. 3, cages 14 are insertable into, and removable from, either side of the rack. [071] As best illustrated in Figs. 19-30, each cage 14 is in the form of a box-like container comprising a cage body 90 and a detachable cage top 92. [072] The cage can be made of any suitable transparent material. Preferably the cage is made of polycarbonate to facilitate the sterilization of the cage. [073] The cage body 90 includes an air intake port 94 provided at the front end 96 of the cage 14. As shown in Fig. 31, the port 94 is covered by a grill 98 provided on the internal wall of the cage body 90 to protect a porous paper filter 100. The filter 10 is secured to a spigot 101 acting as a filter retainer by a frame 102. As a result, the paper filter 100 is located so that mice cannot access the filter medium in any circumstance. Preferably, the paper 100 is water-resistant and does not need to be removed for cage washing. [074] The cage top 92 is recessed at the front end 104 to provide space for a water bottle 106. The water bottle has a tube 108 which passes through an opening 110 in the bottom surface of the lid 92. The back section of the cage top 92 includes an integrally formed rectangular tubular member 113 adapted to support a lateral flange of a conventional V shaped feeder container 112 having a plurality of feed slots 114, as illustrated in Figs. 32-35. [075] Referring now to Figs. 19 and 36, a base frame 120 is a close but not tight fit to the tubular member 113 and covers the feed rack 122. Over this base frame 120 is placed a porous water-resistant paper filter 118 secured by a filter retainer 120 in the form of a grid. The tubular member 113 acts as an air exhaust port 121 of the cage 14.
7 [076] The upper portion of the cage top 92 is sized and shaped such that the internal surfaces of the side portions 122, 124, and 126 of the cage top form an air-tight connection with the external surfaces of the side portions 37a, 37b, and 37c of the shelf 36; and the back edge 128 of the cage top 92 forms an air-tight connection with the vertical surface of the rack module 20. [077] As a result, when the cage 14 is inserted in the rack, the cage 14, the rack module 20, and the shelf 36 form a substantially air tight chamber having two openings: the first opening is the air exhaust port 121 in communication with the interior of the cage 14 and the second opening is the opening 71 in the rack module 20. [078] When the cage 14 is being inserted into the rack, the back edge 128 of the cage 14 urges the flap member 64 towards its opening position thereby permitting air flow from the interior of the cage 14 through the tubular projection 30b formed on the rack module through the opening 71 into the air plenum 70, as illustrated in Fig. 3. When the cage 14 is removed from the rack, the flap member 64 returns, under the force of gravity, to its closing position. [079] As the air intake port 94 is located lower relative to the air exhaust port 121, the natural convection flow of air created in the cage by the heat generated by the animals contained in the cage can ensure sufficient airflow rate to provide good air quality within each of the cages inserted into the rack. To prevent accumulation of harmful gases in the room where the animal caging system is installed, the air exhaust plenum 70 can be connected to a scavenger system through an exhaust hole 132 provided in the rack cover 130. [080] In an alternative embodiment, to further improve air quality in the animal cages, the air exhaust plenum 70 can be connected to a vacuum pump (not shown) through a pressure valve (not shown) so as to achieve periodic or continuos withdrawal of the harmful gases from the cages through the air exhaust port 121, and simultaneous or successive air replenishment through the air intake port 94, in addition to the convection-based air flow described above. [081] To replace the filter 118, the user removes the filter retainer 116 and the filter paper 118. The user then places a pre-cut piece of filter paper 118 of the required pore size. The user then pushes the filter retainer 116 firmly down so that it folds and urges the filter paper 118 into the frame 120. The filter retainer 116 and the frame 120 are sized such that the paper filter 118 is firmly retained in the frame 120. Surplus paper can be trimmed with shears or a 8 knife. Alternatively, the paper 118 can be cut to a size that little or no paper extends past the edge of the frame 120. [082] The user replaces the filter paper 100 in a similar manner. [083] Illustrated in Figs. 40-44 is an alternative embodiment of the present invention. Similarly to the embodiment shown in Figs. 1-39, a rack (not shown) is of modular construction and includes a plurality of rack modules 140. Each rack module 140 includes a chimney member 142 and a pair of integrally formed rack shelves 144.1 and 144.2. The chimney member 142 is provided with a pair of generally vertical slots 146 adapted to receive complementary projection of a first adjacent rack module and a pair of generally vertical projections 148 adapted to be received in complementary slots of a second adjacent rack module. As shown in Fig. 43, the rack module 140 can include additional slots 146 and additional projections 148. [084] As illustrated in Fig. 44, the caging system includes a modified form of a flap 150 of the flap valve 54. The flap 150 is curved to more easily fit into the space available. [085] The rack module 140 buildings vertically and horizontally into a rack. The cages 14 are insertable into, and removable from, the rack in the manner described earlier in this specification. [086] The above description indicates that adjoining modules and related features make sealing contact. However, when the rack system is connected to a vacuum source, or a negative pressure is applied, there is no need for air-tight sealing. Albeit, an air-tight seal will make the vacuum system do less work, therefore air-tight sealing is a preference. [087] Where ever it is used, the word "comprising" is to be understood in its "open" sense, that is, in the sense of "including", and thus not limited to its "closed" sense, that is the sense of "consisting only of". A corresponding meaning is to be attributed to the corresponding words "comprise", "comprised" and "comprises" where they appear. [088] It will be understood that the invention disclosed herein extends to alternative combinations of two or more of the individual features mentioned or evident from the text. All of these combinations constitute various alternative aspects of the invention. [089] While particular embodiments of this invention have been described, it will be evident to those skilled in the art that the present invention may be embodied in other specific forms without departing from the essential characteristics thereof. The present 9 embodiments and examples are therefore to be considered in all respects as illustrative and not restrictive, and all modifications which would be obvious to those skilled in the art are therefore intended to be embraced therein.