AU628067B2 - Controlled atmosphere storage chamber - Google Patents

Description

COMMONWEALTH OF AUSTRALIA The Patents Act 1952-1969 o 0 o o o to *r 0 0 0* t000 0 .4*4 0ro a a 9@ 4O *0 40o 4 0 0 Name of Applicant: Address of Applicant: Actual Inventor: Address for Service: i1 SNSTcS <esey>.ci, -Ci

"TLS",

A-DVANeED-B-I--S-YSTEMS-PTY.--LTD.

62 Cedarleigh Road, Kenmore, Queensland, 4069.

JAMES TREVOR MUNDAY 4( 4 4- 4l G.R. CULLEN COMPANY, Patent Trade Mark Attorneys, Dalgety House, 79 Eagle Street, Brisbane, Qld. 4000, Australia.

COMPLETE SPECIFICATION FOR THE INVENTION ENTITLED: i I CONTROLLED ATMOSPHERE STORAGE CHAMBER The following statement is a full description of the invention including the best method of performing it known to i THIS INVENTION relates to a controlled atmosphere storage chamber which may represent a building interior comprising one or more rooms, a vehicle interior or the interior of a container.

Hitherto conventional air conditioning systems have mainly been used in regard to providing a controlled atmosphere for building interiors and vehicle interiors and o oc .11 CC 00 such systems have been considerably widespread in use.

A conventional air conditioning system in one form a 10-1 includes return ducts wherein fresh or outdoor air together to a :9.06 with a proportion of recirculated air (air returned from the o 0 air conditioned interior) is drawn into means for generating air conditioned air. The generating means includes a mixing O, chamber, preheater, cooler, reheater and fan. In the mixing S chamber the fresh air and recirculated air are controlled by valves and the air is cleaned by appropriate filters such as glass wool filter elements. After filtering the air is preheated by the preheater comprising in one form heating t Spipes through which steam or hot water is passed. The heating pipes are provided with fins which serve to increase their heat exchange area. The air flows along the fins and absorbs heat from the fins. Excess moisture is removed from a portion of the air by cooling. Thus the warmer the air is, the more water vapour it can absorb. Conversely when air with a certain moisture content is cooled, water condenses in the form of tiny droplets which appear as fog. The cooler is i usually in the form of refrigerated coils which thereby precipitates the excess moisture. The moisture content and temperature of the air emerging from the cooler are determined by the temperature of the cooler. This air is then mixed with air coming straight from the preheater so as to obtain an air mixture of the desired temperature. If the moisture content of the mixture is too low, finely atomised S' water is added by spray nozzles. This causes some cooling of .m the air and for this reason the air is passed through the U reheater which is essentially similar to the preheater and gives the air its desired final temperature. There may also be provided a humidifier located in advance of or adjacent to the reheater. Behind the reheater is the fan which forces the conditioned air through feed ducts to the various parts of the building interior. The constant supply of air to the building interior produces a slight excess pressure which fo causes exhaust air to flow back through return ducts. Some of the exhaust air is discharged to the outside environment 0000o or the open air while a certain proportion the °recirculated air) is returned to the means for generating air conditioned air.

Thus from the foregoing a conventional centralised air conditioning system may include the generating means comprising mixing chamber, cooler, optionally a humidifier, reheater and fan and ducts for passing the air conditioned air through the building interior. The ducts may pass 4 through a humidity controller or hydrostat and a thermostat before the air stream is divided into exhaust air and recirculated air which is transferred to the generating means by return ducts.

In the above described centralized air conditioning system all the air is treated in the central air conditioning plant or generating means and conveyed through ducts to the building interior or rooms of the building interior. However I#o4 o there are many variants of the centralized system.

Lo Decentralized systems operate either in conjunction with a central conditioning plant which treats only the proportion of outside air that is introduced into the system or they may be fully decentralized, using self contained cabinet or box type air conditioning units in the various rooms. In such systems the air may be divided into two streams, one of which is heated and the other cooled. In each room these two air streams are mixed in the proportions to produce the desired temperature.

j In another type of conventional air conditioning system use may be made of an evaporative cooling system rather than refrigerated coils and this is mainly included in decentralized air conditioning systems.

However, the conventional air conditioning system does have some disadvantages. As described above heated air is drawn at a given velocity through a cooler such as refrigerated coils or an evaporator and returns cooled air to i i i the building interior. Because these coils or evaporator are at a lower temperature, passing air loses or exchangers heat to the cooler. In this exchange of heat the moisture carrying capacity of cooled air is reduced relative to the temperature and air returned to the building interior is "dried" according to heat lost.

Also the conventional air conditioning process od S relies on the complete exchange of air from the building interior to be cooled and velocity of air and coil 4444 0 temperature controlled to match the total heat load of such *age oo o environment. Cooling is thus effected on the total volume of air in the building interior irrespective of the location of the heat source within the building interior. Under such .tt conditions heat from lights, other appliances and body heat

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iq, radiate, convect and conduct to the total volume of air within the building interior and all of the air is heated *44*4 according to the sum of all heat loads. However, this means that difficulty is experienced at allowing the major working Ssurface of the building interior to be maintained at the rir desired temperature and relative humidity. This means cooling efficency is minimized and dehumidification is maximized. Also heat source components such as lights may overheat and have an impaired working efficiency. In addition since the conventional air conditioning process cools all air to be returned to the building interior or environment and this means that the recirculated air can I 1 I 6 carry only a certain amount of moisture relative to air temperature. Thus more moisture cannot be added at that temperature without condensation occurring.

In other prior art reference may be made to German Patent DE 3131902 where there is described a system for waste heat utilisation from lighting units wherein excess heat from lighting units is collected in the form of warm spent air 0 0 which is associated with a fan exhausting the warm spent air Do L to a cooling unit. However, this reference is not believed relevant to the present invention.

0o 0o0 Reference may also be made to other patent 0 0 specifications which include European Patent Specification published under Publication No. 0 004 450 which concerns an apparatus for promotion of the growing of plants in a controlled environment agriculature facility; U.S. Patent Specification 3 824 736 which describes a method and I t apparatus for the continuous production of plants; U.S.

Specification 3 124 903 which describes a controlled environment room system; Japanese Specification 55-152333 which is concerned with an air conditioning system; Japanese Specification 55-112951 which describes a suspended illuminator system; USSR Patent SU-753394 which describes a l1ant growing chamber having air inlet shutters having surface areas which reduce along the direction of the air flow; and Japanese Patent Specification 52-121951 which describes a cooling apparatus for a greenhouse.

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rL. -i 11111113 s~-r 7 However none of the above prior art references are believed relevant to the present invention.

Possibly one of the most pertinent prior art references is USSR Patent SU-459192 which describes a chamber for growing plants in artificial conditions which includes shelves in the form of flat perforated boxes linked to air inlet pipes. Above the shelves in the chamber are provided It light sources. Plants are placed on the shelves which are ,14 0*09 movable inside the chamber. The incoming air from a cooler a a 0oQo is passed into the interior of the shelves and blows around the plants which are illuminated by the light sources. The used warm air is exhausted from the chamber by exhaust ducting. However this reference is not believed relevant to the present invention because it does not produce a controlled heat envelope around the light source as described hereinafter.

it r It therefore is an object of the present invention to provide a controlled atmosphere storage chamber which ,alleviates the above described disadvantages of conventional air conditioning systems.

The storage chamber of the invention includes: means for generating cooled and pressurized air; (ii) one or more feed ducts associated with the generating means for circulating said cooled and pressurized air within the chamber; L ~i (iii) a plurality of return ducts for returning heat laden spent air to the generating means; (iv) one or more heat sources within the chamber; and a plurality of storage members wherein said one or more of said heat sources is located closely adjacent to a respective storage member; characterized in that the feed ducts and return ducts are separated from each other and the flow of air within the chamber is such as to control heat emission within the vicinity of the or each heat source within a surrounding envelope that represents only a minor proportion of the total volume of the chamber.

There also may be included humidifying means and associated humidifying ducts for circulating humidified air within the chamber. However these components may be omitted if the storage chamber of the invention is used for drying purposes. Suitably the humidifying ducts are separate from the feed ducts and return ducts.

The means for generating cooled and pressurized air 2 for use in the invention may be of any suitable type and thus correspond to a centralized air conditioning system as o described above in regard to the aforementioned prior art.

o a*4 0Thus in one form the generating means may include the mixing chamber, preheater, cooler and reheater. However, a decentralized generating means may also be used which is a Sself contained cabinet including a heater, a fan or impeller for drawing in outside air, a heater and a cooler. Another fan or impeller may also be utilized if required.

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Again, if considered appropriate refrigerated coils or appropriate evaporative cooling means together with appropriate pressurizing means such as a vane pump or centrifugal pump may be utilized.

If desired the air conditioning system may also incorporate a gas bypass system which regulates the temperature of air passing over the refrigerated coils.

The feed ducts associated with the generating means 6 S may be of any suitable type and any suitable shape. The feed ducts may be an integral part of the chamber and thus be part S of the chamber during construction or be added to the chamber 0 a at a later date. Preferably however the feed ducts are of a uniform cross sectional shape.

Not- Suitably also the feed ducts may extend throughout either the longitudinal or transverse dimension of the S chamber.

r rr 0 00 The return ducts are suitably located adjacent the heat sources in the chamber which in one form may comprise electrical lighting such as lighting strips suitably in the 2A form of fluorescent tubes. In e preferred embodiment of the invention there may be provided an elongate storage module or lighting assembly unit having strip lighting attached to its underside and return ducts extending longitudinally of the module.

The return ducts may be of any suitable shape having an endless or continuous side wall which may be circular or rectangular.

In another possible arrangement each module may incorporate one or more feed ducts as well as one or more return ducts.

The return ducts may include an end port for passage of return heat laden air as well as a plurality of spaced side ports located in the side wall of the return duct 0 °o 0a for passage of return heat laden air back to the generating o- means. Alternatively the end ports may be omitted if o 44<* IO desired.

o0 The chamber may incorporate a plurality of the abovementioned storage or lighting modules which are arranged longitudinally or transversely in the chamber and also in stacked relationship or wherein a respective storage module is bound by an upper storage module and a lower storage module. It is also preferred that each storage module have a top surface that is used for shelving for the purpose of storing articles such as perishable articles in the form of flowers, plants, fruit, vegetables or the like requiring a controlled atmosphere either for propagation or storage.

However, it is emphasized that other suitable heat sources .aay be used in accordance with the invention such as electrical heating elements in the form of strips and the like. Alternatively electric light globes may be used in place of fluorescent tubes.

_,1 The humidifying means may be of any suitable type such as for example including an open topped reservoir filled with water which is heated by suitable heating means such as a heating element. A screen may be attached to the open top of the reservoir. Humidifying ducts may have a fan or air blower associated therewith for transfer of humidified air throughout the chamber. Suitably the humidifying ducts may extend throughout the length and/or the width of the chamber.

Reference may now be made to a preferred embodiment o0 G of the invention as shown in the attached drawings wherein: o 00 0. FIG 1 is a plan view of a storage chamber ao constructed in accordance with the invention; "0 4 FIG 2 is an end perspective view of the storage S" chamber shown in FIG 1; FIG 3 is an end view similar to FIG 2 showing the surrounding envelope around the heat sources; H t FIG 4 is a sectional view through a storage module showing the configuration of the return ducts; FIG 5 is an end view of the module of Fig 4 from the direction of arrow t FIG 6 is a perspective drawing showing a cut-away section illustrating the direction of flow of air conditioned air, humidified air and return air; FIG 7 is a view of a storage module different to that shown in Figs 1-6; .i L FIG 8 is a perspective view of the module shown in Fig 7; FIG 9 is a view of a bank or array of modules of the type shown in Fig 7 communicating with a supply air duct and a return air duc-c and showing the flow path of supply and return air; FIG 10 is a view of a storage chamber directed to a different embodiment of the invention to that shown in Figs 7-9; °i0o- FIG 11 is a similar view to that depicted in Fig 9 o «o o. but directed to the embodiment of Fig 10 showing the flow paths of supply air and return air; and FIG 12 is a perspective view of a bank of modules fi f used in the embodiment of Figs 10-11.

In Fig 1 there is shown a chamber 10 subject to a controlled atmosphere constructed in accordance with the invention. The chamber 10 includes air conditioning plant or generator unit 12, feed or supply ducts 13, 13A and 13B, primary return ducts 14, intermediate passage 15 and secondary return ducts 16. Chamber 10 includes doors 17 as well as humidifier 18 and humidifying ducts 19, 19A and 19B.

In Fig 2 there are shown lighting modules 20 each incorporating a housing 21 having strip lighting 22 in the form of fluorescent tubes attached to the underside of housing 21. Housing 21 is of a shallow cuboidal shape as' shown having a top surface or top wall 23 which functions as L e 13 a shelf for the storage of articles of a perishable nature which are subject to the action of the controlled atmosphere in chamber 10. There are also shown partitions 24. Lighting modules 20 include central modules 20A having 12 lighting strips attached thereto and end or side modules 20B having 6 lighting strips attached thereto. There is also shown base wall 25, side walls 26 and top wall 27 of chamber In Fig 3 the flow paths of humidified air as well as air conditioned air is clearly shown by the arrows. Air conditioned air is returned through return ducts 14 as 4Oo discussed previously.

In Fig 3 there is shown heat envelope or .surround rrr V, 28 shown in dotted outline caused by the flow of humidified 0 4r air and air conditioned air as described in more detail hereinafter. Also shown are control sensors 29.

Figs 4-5 show in more detail the structure of return ducts 14 and how they are included in housing 21 of Slighting or storage module 20. Each duct 14 is tapered as shown from inlet end 30 to outlet end 31 for the purpose of *4 equalizing pressure in chamber 10, This means that the Svolume of air is distributed to all parts of chamber equally.

In Fig 6 there is shown lighting modules 20 with a top wall or shelf 23 removed to illustrate the arrangement of return ducts 14 and access ports for entry of return air.

Each duct 14 is provided with side ports 33 and shelves or I i I I ii iii -1---illlllOllIl storage areas 23 are provided with ports 32 for access of return air which has a flow direction as indicated by the arrows.

In another embodiment of the invention as best shown in Figs 7-8 the storage module. may adopt a different shape to that shown in Figs 2-5. In Figs 7-8 each storage module 36 may include a pair of outer supply air or feed air ducts 37 which each bound on intermediate return air duct 38.

Each light strip 39 having mounting flanges 40 may be .1'Q attached to the module 36 in any appropriate manner. The ducts 37 may also include a plurality of spaced feed or supply ports 41. There also may be provided a plurality of 6 4 return air ports 42 which are in the form of spaced rows 43 adjacent a respective light strip 39. There also may be provided partitions 44. There is also included storage recess 45. There is also shown end wall 46.

4 4: 4 It will of course be appreciated that ports 41 and 42 may be replaced by a continuous slot if such is considered appropriate in each of ducts 37 and 38. The desired cross sectional shape of return ducts 37 are also clearly shown in Fig 8.

In Fig 9 there is shown the flow paths of supply or feed air (on the left hand side) and the flow paths of return air on the right hand side of the drawing.

Supply air is fed into modules 36 from main supply duct 47 and flows from supply ducts 37 as shown to flow L around lighting strips 39. Subsequently the air is returned via return ducts 38 to main return duct 48.

In Figs 10-11 a complete ducting system for a storage chamber 50 is shown comprising a plurality of shelf units 49 and spaces 51 located between adjacent vertical rows 52. End rows 52A each comprise a row of single shelf units 49 while intermediate rows 52 comprise shelf units 49 in combination as shown. In Fig 10 each row 52 or 52A comprise a storage rack if desired. There is also shown air 0 conditioning unit 53, main return air duct 54, main supply oo. duct 55, supply ducts 56 and ducts 57 for distribution of supply air into spaces 51. The cold room 50 also comprises •t wall 58 suitably formed from polystyrene or other suitable insulating material. Also shown are spaces 59 between adjacent shelves 49 as well as heat envelope 60 discussed previously. Storage areas 61 are also indicated as well as lighting strips 62.

Sr" In Fig 11 there is shown a view similar to Fig 9 but relating to the embodiment shown in Fig 10. Fig 12 also describes the same embodiment. In this embodiment which is similar to the embodiment of Figs 1-6 there are no supply ducts located in the storage modules or shelf units 49 and supply of air is fed through supply duct 55 to spaces 51 then over lighting strips 62 to return ducts 64 located in shelf units 49 comprising three individual storage modules 66 and finally through main return duct 65 after flowing into plenum 16 chamber 67.

From the foregoing it can therefore be appreciated that the storage chamber of the invention reticulates heat laden spent air to air having appropriate parameters of temperature relative humidity and gaseous composition to flow through a closed or partially closed chamber. After the spent air is returned to the air conditioning plant it is then passed out of the air conditioning plant as cooled air for mixing with steam enriched or humidified air.

.,To The controlled environment chamber may require air S0 temperature and air relative humidity to be maintained within roa desired limits for any specified period of time. These '44' limits are suitably maintained against an increasing :1.11, Stemperature load created by heat energy originating from light and other internal and external sources and by dehumidification effects from cooling devices, and by air 4r 0 S composition balances within the chamber. Air may be transported for cooling without loss of the defined K: atmospheric parameters.

As examples of appropriate limits the air temperature may be maintained between 5-50 degrees C.

o However it is stressed that the air temperature may fall outside these limits if desired.

When the air conditioned air is mixed with the humidified air before entry into return ducts 14 as shown in the Figs 1-6 embodiment the air when drawn into return ducts i.

17 14 may be partially humidified. Partially humidified air is drawn through return ducts 14 and 16 to the air conditioning plant whereby cooled air is thereafter at the appropriate chamber temperature returned to chamber 10 through feed ducts 13, 13A and 13B at a pressure equal to the suction pressure of return ducts 14 and 16.

In the chamber 10 the cooled air may then be mixed with steam or humidified air to regain appropriate atmospheric humidity values as well as defined atmospheric 0 composition.

o 0oe In contrast to conventional air conditioning at a systems as described above, the storage chamber of the 9999 9.9$ invention extracts most of the heat within the chamber at the 04 O source of heat generation of lights and light components.

Because.,,of the efficiency of air extraction past the lights, heat is controlled within a contained envelope or surround 28 L or 60 that represents only a minor proportion of the total S volume of the chamber. Thus, any cooling is mostly confined Sto air heated within envelopes and not the total of the whole closed or partially closed chamber. This allows the major working surface of the chamber to be maintained at the desired temperature and relative humidity, as heating and cooling are largely confined and restricted to envelopes.

Thereby cooling efficiency is maximized and dehumidification is minimized.

i 1 Since the conventional air conditioning system cools all air to be returned to the chamber, the returned air can carry out so much moisture, relative to the temperature of the air. Thus, more moisture cannot be added at that temperature without condensation occurring. The storage chamber of the invention avoids this because dehumidified cooled air is confined to the volume of the envelopes and is therefore only a small fraction of the total chamber volume. The greater part of the chamber (including ,t0 the working surface) is maintained at the desired temperature and relative humidity.

q q Condensation may not occur in the storage chamber site trte 4 V of the invention and yet the chamber and its operating surfaces may be maintained at relative humidities approaching 100%.

Since the invention involves heat extraction at 'ii' heat source, light components do not overheat and, in the range of chamber operating temperatures, lights and their components operate more efficiently and for a prolonged life.

The invention depends on closely matching the temperature of the cooling means to the desired optimum r temperature of the chamber and minimizing the volume of air a V which can be heated within a closed or partially closed chamber by extracting such air. The invention also depends on the manner in which air is retriculated both to and from the operating surfaces whereby heat is extracted at each 19 storage level or shelf level and cooled air is returned to that level without major intrusion of the air volume surrounding operating surfaces.

As the invention allows the volume 'of air surrounding operating surfaces to be maintained at near optimum of temperature and relative humidity, this permits the introduction of moisture as steam, fog or mist to bring relative humidity to set point optimum without condensation.

Therefore the invention is a cost effective method of controlling chambers for temperature, relative humidity, ,o light and gas levels and may be applied to the following m e 0..Q applications or wherever atmospheric environments require I precise control.

*r4 *f S(i) plant growth at defined temperature, relative humidity light, and gas levels; (ii) seed germination; (iii) mushroom growing; (iv) controlled drying of fruit, flowers, vegetables and r nuts etc; cheese curing and other controlled fermentation Senvironments; (vi) food processing applications; (vii) curing of ceramics, pottery and earthenware; (viii) growth rooms for fish and other aquatic animals; (ix) sterile rooms for billogical control and growth of micro organisms;

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i ~iillgll- ~ll~ iP ~I~-ir=lij quarantine and climate controlled enviromments for animal experiments; (xi) specific pathogen free rooms for controlled DNA shedding and genetic engineering; and (xii) operating theatres with defined pathogen free atmospheres.

The invention may also include within its scope a process for use with the abovementioned ducting system and this may include the following steps: generating cooled and pressurized air within an environment chamber; (ii) causing the cooled and pressurized air to flow within the chamber so as to provide a heat envelope or 06 0 0 surround adjacent heat source(s) located in the chamber; and (iii) returning spent and heat laden air from the chamber suitably to be converted into cooled and pressirized air.

It also will be appreciated from the foregoing that 4i the term "chamber" includes within its scope a plurality of C (4 rooms or a single room in a building interior or one or more compartments in a vehicle interior.

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Claims (12)

1. 2. A controlled atmosphere storage chamber as claimed i in claim 1 further including humidifying means and associated humidifying ducts which are separate from the feed ducts and It S return ducts for circulation of humidified air within the chamber. Q 2 3. A controlled atmosphere storage chamber as claimed o, S in claim 2 wherein the humidifying ducts circulate said humidified air to the heat source(s) in conjunction with the feed ducts which circulate said cool and pressurized air to 22 the heat source(s) whereby both the humidified air and cooled 4 and pressurized air is admixed adjacent said heat source(s) to facilitate formation of said surrounding envelope.
2. 4. A controlled atmosphere storage chamber as claimed in any preceding claim wherein the generating means is an air conditioning system. A controlled atmosphere storage chamber as claimed in any preceding claim wherein the return ducts are located adjacent the heat source(s) in the chamber.
3. 6. A controlled atmosphere storage chamber as claimed in claim 5 wherein a respective storage member is located adjacent a corresponding return duct.
4. 7. A controlled atmosphere storage chamber as claimed in claim 5 or 6 wherein the return ducts have a transverse dimension which progressively becomes larger from one end to 0:o" another end.
5. 8. A controlled atmosphere storage chamber as claimed o 0 So. in claim 7 wherein said one end comprises an outlet end for said heat laden return air. 2X: 9. A controlled atmosphere storage chamber as claimed 00 in any preceding claim wherein said heat source(s) comprise ~lighting strips suitably in the form of fluorescent tubes. A controlled atmosphere storage chamber as claimed in claim 9 wherein there are pr:ovided a plurality of storage modules each haviig lighting strip(s) located on a respective underside thereof and a top surface utilized for storage purposes and wherein an internal part forms a corresponding __return duct or ducts. ii c I i; I i r Ir ii i -I 23
6. 11. A controlled atmosphere storage chamber as claimed in claim 10 wherein there is provided an assembly of said storage modules arranged in stacked relationship or wherein a respective storage module is bounded by an upper storage module and a lower storage module.
7. 12. A controlled atmosphere storage chamber as claimed in claim 11 wherein said storage modules are located in said chamber in the form of one or more vertical rows with the feed ducts located above said vertical rows.
8. 13. A controlled atmosphere storage chamber as claimed in any one of claims 10 to 12 wherein each storage module includes a plurality of spaced return air ports located along the length thereof.
9. 14. A controlled atmosphere storage chamber as claimed 1S.i in any one of claims 10 to 13 wherein each storage module o comprises an intermediate return air duct and a pair of outer feed or supply ducts.
10. 15. A controlled atmosphere storage chamber as claimed in claim 14 wherein each outer feed duct comprises a plurality 0i of spaced exit ports where feed air may be fed to the lighting LotS strip(s). a, a
11. 16. A controlled atmosphere storage chamber as claimed in claim 15 wherein the intermediate duct has a pair of spaced Iaa Sa: rows of return air ports wherein each row is located an adjacent lighting strip. .i i i
12. 17. A controlled atmosphere storage chamber substantially as herein described with reference to the accompanying drawings. DATED this 26 day of June, 1992. BIOSYSTEMS RESEARCH PTY LTD By their Patent Attorneys CULLEN CO. 94 4 I 4 94441 A AAA4 4