GB2091453A - Ventilation of Agricultural Buildings - Google Patents

Abstract

An agricultural building installation suitable for storage of produce or housing of livestock is divided into a plurality of zones, each having at least one temperature sensor 30, and a respective air damper 17. A control device monitors the outputs of the sensors 30 in each zone, one at a time, and then causes air dampers 17 to be opened or closed, to increase or decrease ventilation to a zone. Ventilating air may be pumped into a central duct 11 extending through the building, passing into underfloor passages through opened dampers 17, and then rising upwardly through openings in the floor, so as to pass through stored produce. Alternatively, the dampers may be provided in external walls so as to control natural flow of ventilating air through the building. Extra sensors may be provided for the bottom and top of stored produce (27 and 28) respectively, internal roof temperature (29) and for incoming air temperature (26), the control apparatus adjusting the dampers 17 in dependence upon the outputs of all the sensors. Each zone may have a plurality of sensors 30 the output of which is averaged, and a sensor may be provided for external ambient air temperature. <IMAGE>

Description

SPECIFICATION Agricultural Buildings This invention relates to agricultural building installations, and in particular concerns the satisfactory ventilation thereof for the purpose which the building is to serve-for example, for the storage of agricultural produce or for the housing of livestock.

When an agricultural building is to be used for the storage of produce, it is often desirable to provide the building with some means to allowed the forced ventilation of stored produce. This is because it is frequently necessary to harvest produce when the conditions are wetter than ideal, and in order to prevent the rotting or other deterioration of the produce, it must be dried to some extent. It is however easily possible to overdry produce: this again can lead to deterioration of the produce and has the added disadvantageparticularly in the case of cereal crops-of decreasing the crop value because produce is usually sold by weight and the weight to some extent depends upon the moisture content thereof.

Produce stores are known in which ducts are provided under the floor thereof, the ducts having appropriate openings through the floor such that air may be impelled along the ducts and through the openings, to rise through produce heaped on the floor. If necessary, the impelled air may be conditioned-for instance by heating or altering the relative humidity thereof-prior to being passed through the produce to assist drying, and in this way the produce may be dried to a state suitable for storage. Moreover, the produce may be maintained in a generally satisfactory condition during relatively long term storage by driving air therethrough as and when necessary.

Unfortunately, produce stored in a drying shed as just described rarely has a uniform moisture content throughout, especially in the case of a large-scale shed. Thus, drying is likely to proceed somewhat irregularly, and although the drying may be regarded as complete when the average moisture content has falien to an acceptable value, nevertheless some areas may then be overdried whereas others may still be too wet. If such produce is to be stored after drying, it is quite likely that local and rapid deterioration can take place, and if this remains unchecked, deterioration of large masses can result.

In the case of livestock buildings (including houses for poultry), the ventilation requirements to ensure the well-being of animals in the building may vary considerably in different parts thereof, especially in the case of a large-scale building. For instance, one side of the building may be in shade or facing north, whereas the other side of the building may be exposed to sunshine or facing south: in either case, said other side would be expected to require more ventilation for maintenance of a uniform temperature throughout the building. Similarly, different animals may be housed in a single building, or animals at different stages of their development, and again this may lead to varying ventilation requirements.

The usual practice in large-scale animal houses is to provide ventilator which may manually be adjusted as the stockman thinks fit, but such ventilation control is of necessity dependent wholly upon the skill and experience of the stockman. Moreover, it suffers from the considerable disadvantage that adjustment is performed only when the stockman deems it necessary to visit the building, whereas the ambient conditions may change quite rapidly in the course of a day, making more frequent adjustment desirable.

In an attempt to overcome the abovedescribed problem it is known to fit thermostatically-controlled ventilators, where a temperature sensing element is fitted to the ventilator and causes a ventilator to open or close, dependent upon the sensed temperature. The disadvantage of this is however that the element senses the temperature only in the immediate vicinity of the ventilator, and is thus susceptible for example to sunlight falling directly thereon.

Also, as soon as the ventilator opens, the element will be exposed to cool air, and cause the ventilator at least partially to close again, before adequate ventilation of the building has taken place.

It is a general aim of this invention at least to mitigate some of the problems discussed above concerning ventilation in agricultural buildings used for the storage of produce and the housing of livestock.

Accordingly, this invention provides an agricultural building installation including a plurality of air valve mechanisms each of which is disposed to allow the control of air flow therethrough, either to or from an associated area within the building and each of which is selectively operable, the installation further comprising a multiplicity of sensors for positioning within the building at spaced locations, each sensor providing an output dependent upon the sensed parameter in the vicinity of that sensor, and control apparatus for the air valve mechanisms, which control apparatus has a control circuit operating on the outputs of the sensors and causes actuation in the appropriate sense of one or more of the valve mechanisms serving an area the sensor in which indicates unsatisfactory conditions are prevailing.

It will be appreciated that in the building installation of this invention, not only can the conditions be monitored at a relatively large number of locations, ventilation can be given on a selective basis to limited regions or zones of the building, to allow localised control over the conditions in that zone. For example, a building may be divided into eight zones each of which has an associated air valve mechanism operable independently of the other mechanisms associated with the other zones, whereby ventilation may selectively be provided in any one or more zones.

The air valve mechanisms may be located in the outside walls of a building, so as to be able to control the natural flow of ventilating air through the building, or may be located over openings provided in a duct extending through the building, so as to control the flow of air into the building, which air is supplied under pressure into the duct.

The former arrangement is especially suitable for livestock (including poultry) houses, whereas the latter arrangement is more suitable for agricultural produce stores.

In the case of a livestock house, it is preferred for the building to have means to admit air thereinto in an upper part thereof, and for the air valve mechanisms to be provided in the side walls.

to control air flow out of the building as required to maintain the desired conditions within the building. A typical installation may have the floor area divided into eight zones each of which has an associated air valve mechanism and an associated sensor, the control apparatus operating on the output of each sensor in turn and deciding whether actuation of the associated air valve mechanism is necessary.

Each air valve mechanism for a livestock house preferably comprises a louvre mechanism the individual slats of which may all simultaneously be inclined at greater or lesser angles in order to control the air flow therethrough. An electric actuator should appropriately be coupled to the louvre mechanism to allow operation thereof under the control of the control apparatus.

In the case of an agricultural produce store, the installation would include an area on which produce may be loaded. Preferably there is a plenum chamber to which air under pressure may be supplied and having a plurality of outlets leading to the produce storage area, there being an air valve mechanism for each outlet which mechanisms may selectively be operated by the control apparatus dependent upon the outputs of the multiplicity of sensors positioned within stored produce at spaced locations such that each sensor provides an output dependent upon the sensed parameter indicative of the state of produce in the vicinity of that sensor.Should one or more sensors of a region then provide an output indicative of produce having an unsatisfactory condition, the control apparatus will cause actuation of one or more appropriate valve mechanisms to allow more or less air to be passed through stored produce in that region.

Because of the nature of agricultural produce, the produce itself cannot be regarded as being in accurately defined zones, and air intended to pass expressly through produce in one zone of the store will inevitably spread out to some extent into the produce in adjacent zones. Thus, in order to obtain a reasonably accurate estimate of the condition of produce in each zone, it is preferred for there to be several sensors in each zone, each sensor providing an output to the control circuit, and the several outputs from the sensors in each zone being averaged by the control circuit so as to enable a decision to be taken as to whether the associated valve mechanisms for that zone should be operated. Hence, a typical installation may have eight sensors for distribution through each of eight zones, the control circuit monitoring the outputs from all sixty-four sensors.Naturally, other numbers of sensors and zones may be used to suit any particular installation. Similar considerations may apply to a livesotck house, as well.

Each sensor preferably is adapted to sense temperature, but the sensors could be adapted to sense some other parameter, such as relative humidity. The sensing of temperature is however suitable for livestock houses and for produce stores, for in the latter case it may give a good indication of the state of the produce during the storage thereof. Where a mass of produce is loaded into a produce store, it is advantageous for each sensor to be provided on the end of a lance which can be pushed into the produce so as to have the sensor thereof at an appropriate position in the produce, but which can be removed from the produce during the unloading thereof so as to avoid damage to the sensor. The ends of the lances remote from the sensors should have flying leads issuing therefrom, which leads are connected back to the control circuit to allow monitoring thereby of the sensor outputs.

As mentioned hereinabove, normally the sensed parameter will be temperature, though other parameters couls instead be sensed for a particular application. However, in the following discussion of preferred aspects of this invention, reference will exclusively be made to temperature, though it is to be understood that this term is intended to embrace such other parameters as may be sensed.

Turning now specifically to produce stores, it will be appreciated that cooling and/or drying of stored produce cannot effectively proceed unless the temperature within the mass of produce has a higher value than that of the external ambient air.

According;y, it is preferred for there to be an external sensor for the temperature of the external ambient air, and for the control circuit to monitor the output from the external sensor, the control circuit serving to inhibit the supply of air under pressure into the plenum chamber if there is an inadequate differential between the external sensed value and the average of that within the produce. The store installation conveniently includes at least one electric-motor-driven fan to impel air into the plenum chamber, in which case operation of the or each fan motor should be inhibited during such time as there is an inadequate differential, as mentioned above.

Conveniently, the minimum magnitude of the differential is adjustable, for instance over the range of from 1 to 10 C.

In order to allow better monitoring of the produce being stored, it is advantageous for there to be at least one further pair of sensors, and preferably one pair for each zone, positioned to monitor the temperature at the bottom and top of the stored produce. If such further sensors detect a temperature differential over the depth of stored produce in excess of a maximum permissible value (which preferably is adjustable over a range of from 1 O to 50C), then the plenum chamber should be supplied with air under pressure to drive air through the produce. Of course when a pair of further sensors are provided for each zone, then the valve mechanisms should be operated appropriately to ensure air is driven only through those zones where there is an excessive temperature differential.

The store installation may be arranged to allow the air supplied under pressure to the plenum chamber to be drawn from outside the store or from within the store, above stored produce.

Though external air normally would be used in the case of the first-mentioned sensors indicating excess produce temperature over external ambient temperature, it is preferred for air drawn from within the store to be recirculated in the case of an excess temperature differential from top-to-bottom of stored produce.

A problem associated with known produce stores such as have been described hereinbefore is that of condensation, particularly on the roof, for this can lead to droplets falling on the produce.

In order to reduce the likelihood of condensation forming, it is preferred for there to be provided a third sensor, mounted internally on the store roof to detect the temperature thereof and to supply an output indicative thereof to the control circuit.

The control circuit could then cause the or each fan to start operating, recirculating air, whenever an excessive temperature differential occurs between the top of the stored produce and the roof-typically adjustable over the range of from 1 O to 50C. However, the fans used to supply air to the plenum chamber are of necessity relatively large and hence have a high power consumption: it is preferred therefore for the control circuit to cause one or more relatively small auxiliary fans to start operating to recirculate air in the event that an excessive roof/top-of-produce temperature differential is detected. Such auxiliary fans may have associated therewith electrically-operated heaters, which are energised at the sme time as the auxiliary fans, to assist the reduction of condensation formation.

Yet another possibility is to provide electric heating elements along the roof, which elements are energised when an excessive roof/top-ofproduce temperature differential is detected.

Provided that such elements are sufficiently well distributed over the roof, there may be no need to provide separate auxiliary fans, nor for the control circuit to cause the main fans to operate.

In a preferred form of store installation of this invention, the store itself comprises a building having a plenum chamber in the form of a duct running centrally along the length of the building from one end to the other, there being fan assemblies at each end of the duct to supply air under pressure thereinto. There may be a plurality of fans at each assembly, individually controllable to allow the air impelled into the duct to be matched to the number of zones to which air is to be supplied. The floor on which the produce is stored preferably has slatted, louvred or other.

openings therein, through which air from the duct may pass so as to pass through produce thereon, there being air dampers for the slatted, louvred or other openings to allow control over which zones are supplied with air. Adjacent the fan assemblies, interconnected fresh air dampers and recirculated air dampers may be provided, fitted with electric actuators which may be energised by the control circuit, so as to allow the fans to draw solely fresh air from outside the store, solely recirculated air from within the store, or blends of recirculated and fresh air, thereby obtaining within the duct air under pressure at an appopriate temperature for the produce.

Instead of the floor itself being slatted or louvred and there being underfloor ducts supplying air thereto, the floor may be solid with surface ducts disposed thereon, the surface ducts having suitable openings to allow the egress of air therefrom, and being connected back to the main duct plenum chamber via appropriate air dampers.

By way of example only, two specific embodiments of agricultural building installations constructed in accordance with this invention will now be described in detail, reference being made to the accompanying drawings, in which: Figure 1 is a diagrammatic partially-broken side view of part of an agricultural produce store installation of this invention; Figure 2 is a plan view, again partially broken away, of the store of Figure 1; Figure 3 is an end view of the store of Figures 1 and 2; Figure 4 is a detail view on an enlarged scale of one end of the store shown in Figure 1; Figure 5 is a block diagram of a control circuit used with the store of Figures 1 to 4; Figure 6 is a side view of a livestock house as a second embodiment of this invention; Figure 7 is a diagrammatic plan view of the house of Figure 6; and Figure 8 is a diagrammatic vertical sectional view through the house of Figures 6 and 7, showing the air-flow therethrough.

Referring initially to Figures 1 to 3, there is shown a store shed for the storage of agricultural produce, arranged so that produce loaded therein may be stored for relatively long periods and monitored for the deterioration thereof. The store shed comprises an agricultural building 10 of conventional construction, but modified so as to have a duct 11 extending centrally from one gable end of the building to the other. Also, the floor in the building to both sides of the duct 11 is raised slightly, as indicated at 12 (Figure 1), so as to define air passageways therebeneath and the two main areas 13 and 14 of the floor on which produce may be loaded are slatted or otherwise provided with openings through which air may issue from beneath the floor, to pass through produce loaded on the floor.By means of appropriate walls, such as those shown diagrammatically in Figure 2 at 15, the areas 13 and 14 are each divided into four zones such that air supplied to the floor beneath one zone does not issue through the openings in the floor in another zone.

The zoned spaces beneath the floor each are provided with a plurality of apertures 1 6 (Figure 4) allowing comniunication from the duct 11 to the zones spaces, the apertures being provided with dampers 1 7 which allow that communication to be shut off or opened, as required. All of the dampers 17 for each zoned area are connected together, so that all of the apertures for any one zoned area may be opened or closed simultaneously; the arrangement is however such that all the dampers for each zoned area can be controlled independently of the dampers for other zoned areas. Electricallyoperated actuators, such as linear actuators or electric motors, are provided for driving the dampers between the extreme settings thereof.

At each end of the duct 1 there is an assembly of four motor-driven fans 18, each fan being independently controllable and adapted to impel air into the duct 11, for distribution to whichever zoned areas have their apertures 1 6 opened by the associated dampers 17. The number of fans 18 operated at any given instant is selected having regard to the number of zones having their apertures open, in order that there may be an adequate supply of air to the duct 11.

The fans 1 8 may draw air either from outside the building 1 0, or from within the building but from above any produce therewithin, dependent upon various factors as will be described hereinafter. In order to allow selection of the source of air impelled by the fans 18, there are provided a fresh air intake damper 1 9 and two recirculating air dampers 20 at each end of the duct 11 , which dampers 19 and 20 at the two ends of the building are inter-connected such that when if the fresh air intake dampers 19 are fully open the recirculating air dampers 20 are fully closed, and vice versa.Moreover, intermediate settting may be selected; that is to say, the fans 1 8 may draw mixtures of both recirculated air taken from above any stored produce and fresh air drawn from outside the building through the intake dampers 1 9. Again, electrically-operated actuators, such as linear actuators or electric motors, are provided for operating the dampers 19 and 20.

The installation includes control apparatus which serves to monitor the produce stored in the above-described building and to control the operation of the fans 18 and dampers 17, 19 and 20 as required. The control apparatus operates on the basis of temperature, sensing the temperature at various points as will now be described and controlling the supply of air to the zoned underfloor spaces, so that air will be driven through stored produce, as appropriate.

Externally of the building 10, at the two ends thereof, are provided ambient air temperature sensors 25 and at least one further temperature sensor 26 is provided within the duct 11, to sense the temperature of air being impelled therein, by the fans 1 8. Further temperature sensors 27 are provided on the main floor areas 1 3 and 14, one for each zone, and suspended from the roof are temperature sensors 28, adapted to sense the temperature at the top of produce loaded into the store. Two further temperature sensors 29 are mounted on the roof itself, within the building and centrally above the floor areas 13 and 14, so as to sense the temperature of the roof itself. Finally, sixty-four temperature sensors 30 are provided, eight for each zone and distributed generally as shown in Figure 2.Each of the sensors 30 is provided on an individual lance (not shown) comprising a relatively small diameter metal tube approximately 2 metres long, such that the lance may be thrust into produce loaded in the store so that the sensor thereof may sense the temperature of produce at the vicinity of the end of the lance. The other end of each lance is provided with a flying lead, for connection back to a control circuit, and all of the other temperature sensors 25 to 29 mentioned hereinbefore are also connected back to the control circuit.

The electrical actuators for the dampers 1 7, 1 9 and 20 as well as each fan motor are all operated under commands from the control circuit, and are appropriately connected thereto for that purpose.

The control circuit itself will now be described in detail, reference being made to the block diagram thereof, shown in Figure 5. The outputs from the sixty-four sensors 30 are supplied to a set point controller 35, which is adapted to scan each sensor output one at a time, typically with a sampling rate of one every three seconds. This sampling rate may however be adjustable to suit a particular application. The set point controller 35 allows setting of a different temperature control point for each of the eight zones; this feature allows the store to be loaded with produce of a varying condition, or at different times-in the latter case drying of the first-loaded produce will already have commenced when later further produce is loaded.

The set point controller 35 provides an output on line 36, which output is indicative of whether the produce stored in any particular zone is too hot, and thus requires air to be supplied thereto, by operating the fans 1 8 and opening the dampers 17 of the apertures 16 of that zone. In arriving at that decision, the set point controller 35 averages the outputs of the eight sensors 30 for each zone in turn, compares that average with the set point for that zone, and then provides on line 36 an output indicative of whether or not that zone requires air to be supplied thereto.

Line 36 carrying the output from the set point controller 35 leads to a high/low controller 37, to which the outputs from the ambient air temperature sensor 25 and the duct temperature sensor 26 are also supplied. The high/low controller 37 allows manual setting of the maximum and minimum permissible temperatures of the air to be supplied to the underfloor zoned spaces for driving through stored produce: again, this controller 37 may allow different limits to be set for each zone, in order to give maximum flexibility and to enable the store to be loaded at different times with produce in different conditions and yet still successfully dry and maintain the produce in a satisfactory condition.The output from the high/low controller 37 is supplied on line 38 to a damper control 39 which serves to provide commands for the operation of the actuators for the fresh air intake dampers 1 9 and recirculating air dampers 20, at the two ends of the duc;t 11.

Because the high/low controller 37 also serves to sense the temperature of air within the duct 11, a form of feed-back control is achieved, by means of which the damper control 39 may cause the dampers 1 9 and 20 to be adjusted until a satisfactory air temperature within the duct 11 is achieved, lying within the set limits for maximum and minimum temperature. If however after a preset period of operation the temperature within the duct 11 as measured by the duct sensor 26 cannot be brought within the limits set on the controller 37, then the controller 37 shuts down the entire system for a predetermined period, but allows a fresh attempt at reaching a stable equilibrium at the expiry of that period.

The high/low controller 37 also supplies an output to a fan control 40, arranged to command the required number of fans 18, having regard to the number of zones which require air to be supplied thereto. In the installation of this embodiment, the arrangement is such that one fan at each end pf the duct 11 is brought into operation for each two zones requiring ventilation air to be supplied thereto.

The dampers 17 of the apertures 16 between each zoned underfloor space and the duct 11 are under the control of switch unit 41. The operation of this switch unit is timed to the operation of the set point controller 35, such that an output on line 36 from the controller 35 indicating that air should be supplied to a given zone causes the switch unit 41 to open the dampers 1 7 of that zone; conversely, an output indicating that no air should be supplied to a particular zone causes the switch unit 41 to close the dampers 17 for that zone.

Because it would be wasteful of electrical energy to supply air to the duct 11 for distribution through produce when the temperature of that air is only very slightly below that of the produce itself, there is provided an ambient temperature/produce temperature differential control 42, which allows manual setting of the minimum permissible differential-typically lying within the range of from 1 to 100C. If the control 42 indicates that there is an insufficient differential, then operation of the fans 1 8 is disabled and the damper control 39 serves to close the fresh air intake dampers 17.

The outputs from the sensors 27 at the floor level and sensors 28 at the top of stored produce are supplied to a lower/upper differential control 43, which allows manual setting of the maximum permissible temperature differential, lying typically within the range of from 1 to 50C. If a temperature differential in excess of the set differential is detected, for any given zone, then an output from control 43 serves to cause the switch unit 41 to open the appropriate dampers 17 for the apertures of that zone, as well as to cause the fan control 40 to energise the appropriate number of fans 18.Moreover, an output from the control 43 causes the damper control 39 to close the fresh air intake dampers 1 9 and open the recircualting air dampers 20but only so long as the output on line 36 indicates that primary cooling air is not required by any given zone.

The output from the roof sensors 29 and the sensors 28 at the top of stored produce are supplied to a roof/upper differential control 44 which allows manual setting of the maximum permissible temperature differential, lying typically within the range of from 1 O to 50C. If the differential exceeds the set differential- indicating that moisture is likely to condense on to the roof and then form droplets which would fall into stored produce-an output is provide from the control 44 which operates in precisely the same way as the output described above from the lower/upper differential control 43.As an alternative however an output from the roof/upper differential control 44 may be used either to control separate, relatively-small power auxiliary fans and/or heaters disposed over the produce so as to minimise the risk of condensation occurring, or to control heating wires distributed over or immediately adjacent the inside surface of the roof, directly to vapourise such moisture as may condense on the roof before the moisture forms droplets. In either of these two cases, the output from the control 44 would be disconnected from the output from the lower/upper differential control 43.

A separate manual over-ride is provided for each of the controls 42, 43 and 44, to allow disabling of that control, thus giving the overall control circuit maximum flexibility.

It will of course be appreciated that the overall control circuit described with reference to Figure 5 operates on a timed basis, the various parts of the control circuit having to operate in synchronism with one another. Appropriate clock arrangements must therefore be provided for this purpose but such matters are well understood in the art and will not be described in detail here.

It is useful for an operator of the store to know the precise condition of produce within the store.

Consequently, it is preferred for there to be provided displays indicating for example the temperature sensed by the sixty-four sensors 30--and conveniently this is achieved by having a single temperature display and a second display which indicates the position of the sensor having its sensed temperature for the time being displayed. As mentioned hereinbefore, it is convenient for the set point controller 35 to scan each sensor 30 one at a time, at a sampling rate typically of one every three seconds, and then the temperature as determined by that controller 35 can directly be displayed, a second display indicating the sensor in question. Such a display arrangement may also include suitable switches allowing the display of the sensed temperatures by the various other sensors described above.

Moreover, in order to obtain a permanent record of the sensed temperatures, it is preferred to provide a printer appropriately coupled to the display arrangement, which printer may print out a record of the temperature sensed at each sensor together with the location of the sensor, either on demand or at regular intervals-for instance once every 24 hours.

Referring now to Figures 6 to 8, there is shown a livestock house of this invention, which house is considerably simpler than the above-described produce store, in that only natural ventilation (rather than forced ventilation as in the preceding embodiment) is employed and only a single sensor is provided for each zone of the house. The livestock house 50 is essentially of conventional construction, except that along each long side wall 51 of the house there are provided four spaced louvre ventilators 52, each of which is fitted with an electrical drive mechanism, such as a linear actuator or an electric motor. Each louvre ventilator may thus be operated independently of the others, upon being driven by a control signal provided by a controller 53.

The floor area of the house is divided into eight zones 54, four along each side of the building and each served by a louvre ventilator 52. Each zone has a temperature sensor 55 mounted therein, approximately centrally in the zone and at an appropriate height above the floor. Each sensor is connected back to the controller 53 such that the controller may operate on the output of each sensor, in turn.

The apex 56 of the house is constructed such that gaps 57 are provided at spaced intervals therealong, through which gaps 57 air may enter the house, as shown in Figure 8. Provided that a ventilator 52 is at least partially open, air may leave the house, again as shown in Figure 8, thereby providing natural ventilation for the interior of the building.

The floor area cannot of course be divided into precise zones each of which is accurately controlled by the associated louvre ventilator, and each zone inevitably merges into the adjacent zones at its edges. Nevertheless, the described arrangement allows satisfactory control of air flow through the livestock house, to give substantially the required temperature generally at any point.

It will be appreciated that the controller 53 may be greatly simplified as compared to that described with reference to Figures 1 to 5. In particular, only eight sensors have to be monitored, and no account need be taken of external ambient conditions, nor roof temperatures. Moreover, only the louvre ventilators are controlled, and the controller does not have to be able to control ventilation or recirculating fans, nor heaters. The controller 53 nevertheless operates on the eight sensors 55 and controls the eight ventilators 52 in much the same manner as the control circuit described hereinbefore monitors the associated sensors and controls the respective dampers, and consequently a description of a suitable controller 53 is here omitted.

Claims (22)

Claims

1. An agricultural building installation including a plurality of air valve mechanisms each of which is disposed to allow the control of air flow therethrough, either to or from an associated area within the building and each of which is selectively operable, the installation further comprising a multiplicity of sensors for positioning within the building at spaced locations, each sensor providing an output dependent upon the sensed parameter in the vicinity of that sensor, and control apparatus for the air valve mechanisms, which control apparatus has a control circuit operating on the outputs of the sensors and causes actuation in the appropriate sense of one or more of the valve mechanisms serving an area the sensor in which indicates unsatisfactory conditions are prevailing.

2. An installation according to claim 1, wherein the air valve mechanisms are located in the outside walls of the building, so as to be able to control the natural flow of ventilating air through the building.

3. An installation according to claim 2, wherein the building has means to admit air thereinto in an upper part thereof, and the air valve mechanisms are provided in the building side walls, to control air flow out of the building.

4. An installation according to claim 3, wherein the floor area of the building is divided into eight zones each of which has an associated air valve mechanism and an associated sensor, the control apparatus operating on the output of each sensor in turn and deciding whether actuation of the associated air valve mechanism is necessary.

5. An installation according to claim 1, wherein the building includes an area on which agricultural produce may be loaded, a plenum chamber to which air under pressure may be supplied and having a plurality of outlets leading to the produce area, there being an air valve mechanism for each outlet which mechanisms may selectively be operated by the control apparatus dependent upon the outputs of the multiplicity of sensors positioned at spaced locations within stored produce such that each sensor provides an output dependent upon the sensed parameter indicative of the state of produce in the vicinity of that sensor.

6. An installation according to claim 5, wherein the produce area is divided into a plurality of zones and there are several sensors provided for each zone, each sensor providing an output to the control circuit, and the several outputs from the sensors in each zone being averaged by the control circuit so as to enable a decision to be taken as to whether an associated valve mechanism for that zone should be operated.

7. An installation according to claim 6, wherein there are eight sensors for distribution through each of eight zones, the control circuit monitoring the outputs from all sixty-four sensors.

8. An installation according to claim 6 or claim 7, wherein each sensor is provided on the end of a lance which can be pushed into the produce loaded in the building so as to have the sensor thereof at an appropriate position in the produce for sensing the temperature thereof.

9. An installation according to any of claims 5 to 8, wherein there is an external sensor for the temperature of the external ambient air, and the control circuit is arranged to monitor the output from the external sensor, the control circuit serving to inhibit the supply of air under pressure into the plenum chamber if there is an inadequate differential between the external sensed value and the average of that within the produce.

10. An installation according to claim 9, wherein there is at least one electric-motor-driven fan to impel air into the plenum chamber, the operation of the or each fan motor being inhibited when the control circuit detects there is an inadequate differential.

11. An installation according to claim 10, wherein the control circuit has means to allow adjustment of said differential.

12. An installation according to any of claims 5 to 11, wherein there is at least one further pair of sensors, adapted for positioning to monitor the temperature at the bottom and top of produce stored in the building.

1 3. An installation according to claim 12, wherein there is one further pair of sensors for each zone of the area.

14. An installation according to claim 12 or claim 13, wherein the control circuit is arranged to monitor the or each further pair of sensors and to cause air to be supplied under pressure to the plenum chamber should the temperature difference detected between a pair of the sensors exceed a predetermined maximum.

1 5. An installation according to any of claims 5 to 14, wherein there is provided a third sensor, mounted internally on the roof of the building to detect the temperature thereof and to supply an output indicative thereof to the control circuit.

1 6. An installation according to claim 15, wherein the control circuit is arranged to cause the recirculation of air within the building whenever the temperature differential between the top of stored produce and the roof exceeds a pre-set maximum value.

1 7. An installation according to claim 15, wherein there are electric heating elements provided along the roof, the control circuit being arranged to energise the elements whenever the temperature differential between the top of stored produce and the roof exceeds a pre-set maximum value.

18. An installation according to any of claims 5 to 17, wherein the installation comprises a building having a plenum chamber in the form of a duct running centrally along the length of the building from one end to the other, there being fan assemblies at each end of the duct to supply air under pressure thereinto.

1 9. An installation accordingly to claim 18, wherein the floor on which produce may be stored has slatted, louvred or other openings therein, through which air from the duct may pass so as to pass through produce thereon, there being air valve mechanisms for the slatted, louvred or other openings to allow control over which zones are supplied with air.

20. An installation according to claim 1 8 or claim 1 9, wherein there are fresh air dampers and recirculated air dampers provided adjacent the fan assemblies, which dampers are fitted with electric actuators which may be energised by the control circuit, so as to allow the fans to draw solely fresh air from outside the store, solely recirculated air from within the store, or blends of recirculated and fresh air.

21. An installation according to any of the preceding claims, wherein each air valve mechanism preferably comprises a louvre mechanism the individual slats of which may all simultaneously be inclined at greater or lesser angles in order to control the air flow therethrough.

22. An agricultural building installation substantially as hereinbefore described with reference to and as illustrated in Figures 1 to 5 or in Figures 6 to 8 of the accompanying drawings.