GB2121263A - Hydroponic apparatus for growing crops - Google Patents

Abstract

Hydroponic apparatus includes racks 62 for holding seed-bed trays. Nutrient distribution manifolds 59 have spray nozzles 61 for spraying water and/or nutrient solution over the seed-bed trays. The manifolds have drive motors 60 which rotate and/or oscillate them about a vertical axis, to give improved distribution of the solution; alternatively there may be drive means to translate the manifolds along the racks. Alternate racks 62 slope in opposite directions so that a tray can be moved along the rack as the crop grows and needs more headroom. A rack in the form of a continuous helical path is also described in which the headroom increases along the path. <IMAGE>

Description

SPECIFICATION Hydroponic apparatus for growing crops This invention relates to apparatus for growing crops hydroponically. It can be used for growing crops such as hydroponic grass for cereal grain seeds. It is also applicable to growing other crops, including bean shoots and bamboo shoots, and for the testing of various seeds for germination standards.

Known hydroponic grass growing apparatus generally includes an enclosure housing racks for supporting seed-bed trays. A sump is provided at the bottom of the enclosure, and in use this in filled with water containing a hydroponic nutrient in solution. The enclosure contains a number of fixed spray nozzles which are directed towards the trays, and a pump which operates periodically to supply the hydroponic nutrient solution from the sump to the nozzles. The spray nozzles provide a fine atomised spray to the seeds, and excess solution drains back to the sump. Lights are provided within the enclosure to provide the light conditions necessary for satisfactory crop growth, and in later variations of such equipment the enclosure is hermetically sealed and cooling units are provided to maintain desired temperature and humidity conditions within the enclosure.

An example of such apparatus can be seen in U.K. Patent Application Publication Nos. 2030832 to 2030835.

While this known apparatus is capable of growing hydroponic grass of acceptable quality and at acceptable production rates, it suffers from a number of problems. First, it is difficult to ensure that all areas of the seed-bed trays are sufficiently evenly irrigated with the nutrient solution, there being a danger that some areas will be overirrigated and some will be under-irrigated.

Previous attempts to solve this problem have involved the use of a large number of spray nozzles. However, this requires an extensive stationary manifold system to distribute the nutrient solution to the nozzles, resulting in the need for a large quantity of the nutrient solution, a relatively large capacity pump or pumps, and a large sump. Apart from the cost of all this and the complex maintenance problems involved in cleaning nozzles, the relatively large size of the pump is an especial disadvantage if the apparatus is supplied with electrical power other than three phase. In many parts of the world, three phase electrical supply is not readily available to most users and the large single phase motors thus needed place excessive demands on the electrical supply capacity.Furthermore, the large sump must generally be located within the floor of the enclosure which means that the enclosure has to be elevated above the general ground level thus rendering access, entry and exit more difficuit and the whole apparatus more exposed to adverse wind conditions. In some versions of the prior art apparatus where the excessively large sump is located in the floor of the enclosure, its top is not always fully covered over thus leaving potentially hazardous gaps in the general level of the floor, making operation more difficult for the workers.

On the other hand, full or partial enclosure of the floor mounted sump renders cleaning and inspection more difficult.

Furthermore, the use of a large number of spray nozzles still does not give complete uniformity of irrigation, and the large number of spray nozzles and associated filters render inspection and cleaning more laborious and less efficient.

A further problem with the known apparatus is that the usage of space within the enclosure is not very efficient. This stems from the need to have space above newly germinated seeds into which the plants can grow. This problem limits the rate at which a given size of enclosure (with a given capacity of ventilation and iighting equipment, etc.) can produce a crop, and therefore limits the economy of the process. It has been proposed to solve this problem by the use of an array of horizontal racks for holding seed-bed trays, in which the vertical spacing between adjacent pairs of the racks varies. With such an arrangements, it is possible for more narrowly spaced racks to be used for seed-bed trays containing newly germinating seeds, and for these trays to be transferred to racks with a greater spacing as the plants in them grow and require more room.

However, this greatly increases the labour involved, because the trays have to be transferred from one rack to another as the plants grow.

According to one aspect of the present invention there is provided hydroponic apparatus comprising vertically spaced rack portions for holding a plurality of seed-bed trays along the length thereof, characterised in that the spacing between one rack portion and a rack portion above it varies along the length of the rack.

In one form, this may be provided by having alternate racks slope by different amounts, or preferably in opposite directions. In another form, the vertical spacing between one or more adjacent pairs of rack portions differs from that between one or more others, and the apparatus is characterised in that the racks form a continuous path, successive points along which are vertically spaced from each other, e.g. in a helical form. A manual and/or gravity and/or mechanical handling system can then transport the trays along this path. The headroom over the path into which plants may grow may then increase along the path.

According to a second aspect of the invention.

there is provided hydroponic apparatus comprising a rack or racks for holding seed-bed trays, arranged in or for arrangement in an enclosure, and one or more spray nozzles arranged to spray a hydroponic nutrient solution and/or water over the seed-bed trays when in the racks, characterised in that drive means is provided, arranged for moving the nozzle(s) so as to successively spray different area of the seed-bed trays. This enables one nozzle to provide coverage to a greater area of the seed-bed tray.

Preferably a plurality of racks are vertically spaced, and a plurality of vertically spaced spray nozzles is provided, each of which is movable in a generally horizontal plane by the drive means.

Where the vertical spacing of the racks varies from one adjacent pair of racks to another, preferably the vertical spacing of the nozzles also differs. The drive means may be arranged to translate the nozzle(s) along the rack or racks. Preferably, the drive means is arranged to rotate or oscillate the n6zzle(s) about a generally vertical axis. Preferably a plurality of racks are vertically spaced and a plurality of vertically spaced spray nozzles are formed in or mounted on a nutrient solution distribution manifold which is arranged for rotation or oscillation about the generally vertical axis. The nozzle(s) may suitably each be arranged to give a fan-shaped spray, so that the oscillation or rotation causes corresponding oscillation or rotation of the area covered by the fan.

A number of hydroponic crop growing units according to the invention will now be described by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a diagrammatic plan view of a first hydroponic unit, Fig. 2 is a vertical cross-section of the unit shown in Fig. 1, on the line Il-Il, Fig. 3 is a diagrammatic plan view of a modified version of the unit of Fig. 1, Fig. 4A is a vertical section through a part of the unit, Fig. 4B is a modification of Fig. 4A, Fig. 5 is a plan view of a trolley and seed-bed tray shown in Fig. 4, Fig. 6 is a diagrammatic elevation of part of a further modified unit, in the direction of arrow A in Figs. 1 and 3, Fig. 7 shows an alternative hydroponic unit diagrammatically, Fig. 8 is an end elevation of a modified version of the unit of Fig. 7, Fig. 9 is a diagrammatic plan view of part of another embodiment of hydroponic unit, and Fig. 10 shows diagrammatically an alternative hydroponic unit.

Referring firstly to Figs. 1 and 2, the hydroponic crop growing unit comprises an enclosure 8 having walls 10, suitably provided with insulation.

In the centre of the floor of the enclosure is a sump 12 for hydroponic nutrient solution and/or water. Inside the enclosure 8, there is a helical path 14 for seed-bed trays. The path 14 has an entry portion 16 and an exit portion 18, both of which pass through openings in the wall 10 from a loading and unloading area 20. The entry and exit portions 16, 18 are both tangential of the helical path 14, the entry portion 16 being at the top of the helix and the exit portion 18 at the bottom.

In the loading and unloading area 20, an elevator 24 is provided at the start of the entry portion 1 6. This elevator 24 is outside the enclosure wali 10, for ease of maintenance and cleaning, and so that its mechanism is not affected by conditions within the enclosure.

As best seen in Fig. 2, by virtue of the shallow helical form of the path 14, it effectively presents a large number of vertically spaced, almost horizontal racks 22. The helical path is arranged to get steeper as it progresses from the top to the bottom, so that the vertical spacing between these racks 22 gradually increases towards the bottom.

If found more convenient, it would be possible for the helical path 14 instead to have a slope whic,h varied in discrete steps, so that there would be a number of racks with the same relatively narrow vertical spacing at the top of the helical path, followed by a number with a slightly wider spacing, and so on to the bottom of the helical path.

As seen in Figs. 4 and 5, the racks 22 take the form of horizontal, radially extending rods supported by vertical posts 26. They support rails 30 running along the entire length of the path 14, on which wheeled trolleys 28 can run. A train of such trolleys passes intermittently through the unit along the path 14 from the top of the helix to the bottom, propelled by a suitable mechanical handling system and/or by gravity. Fig. 4A shows such a trolley with wheels 60 running on the rails 30, while Fig. 4B shows a trolley with slides 62 running along the rails 30. The trolleys 28 support seed-bed trays 32, in which grass 34 or another desired crop grows hydroponically. As seen in Fig.

5, the trays 32 are not quite rectangular, but have their longest sides divergent so as to fit more efficiently into the circular path 14. However, this is not essential and rectangular trays could be used.

Around the periphery of the enclosure 8, and in a battery 36 in the middle of the helical path 14, there are provided fluorescent light fixtures 38.

These provide the most effective ambient light conditions for the satisfactory growth of the crop.

Also provided servicing the enclosure are generally conventional heating and cooling and/or air circulation units to control the temperature humidity and movement of air within the enclosure and/or the exchange of air or other gases to and from the outside temperature.

A door 40 is provided into the enclosure 8 from the loading and unloading area 20, to permit access into the enclosure by workers. However, it will be understood that such access will only be required for purposes of maintenance and cleaning, since the regular task of loading fresh trays 32 of seeds onto the entry portion 16 andF unloading trays of the crop produced from the exit portion 1 8 are effected from outside the enclosure, in the area 20. This provides a more' acceptable working environment for the workers.

Because of the gradually increasing spacing between the racks of the path 14, the narrowest spacings are used when the trays of fresh seeds are first introduced into the unit. As the trays pass along the path 14, the growing plants acquire more headroom. Better utilisation of the space available is thus realised.

The unit does of course require a means of supply of hydroponic nutrient solution from the sump 12 to the trays as they progress along the path 1 4. This could be achieved by the use of a large-number of conventional fixed nozzles, operated periodically so as not to saturate the seeds and growing plants too much, while still obtaining the advantages mentioned above. Or there could be a number of nozzles which are rotatable or oscillating about a plurality of fixed vertical axis. However, in the embodiment shown in Figs. 1 and 2 a smaller number of generally horizontally directed travelling spray nozzles 42 are used. These are arranged on four vertical distribution manifolds 44, which depend from a horizontal boom 46 rotatable about a pivot 48 which is concentric with the helical path 14.The distribution manifolds 44 straddle the helical path 14, so that the spray nozzles 42 are directed onto the plants growing in the trays 32. The nozzles 42 may be fixed relative to the boom 46, or they too may be rotatable or oscillating in a a generally horizontal plane to improve the distribution of the nutrient solution and/or water. The spacing of the nozzles 42 down the distribution manifolds 44 gradually increases from top to bottom, broadly corresponding to the increasing spacing of the levels of the racks 22 of the path 1 4. Thus, there is a spray of nutrient solution and/or water substantially provided to each level of the path 14.

Hydroponic nutrient solution is supplied by a pump (not shown) through plumbing fixtures (not shown) from the pivot point 48 to the boom 46, from where it is distributed down the manifold 44 to spray nozzles 42. Excess solution falls from the trays 32 to the floor 11 of the enclosure, which slopes towards the sump 12 so that the solution recirculates. Alternatively, drainage channels can be provided all the way around the path 14 to return excess nutrient solution to the sump 1 2.

As the boom 46 rotates, nutrient solution and/or water will be provided to different ones of the trays along each level of the path 14, so that over a period of time all the trays are sprayed evenly. Further, this requires considerably fewer spray nozzles than if the nozzles were all fixed, and the distribution manifold system is of smaller capacity so that a smaller total quantity of nutrient solution can be used. Also, a smaller capacity pump is used.

The boom 46 could be rotated by an electric motor, or by a pneumatic motor but a hydraulic motor operated by the nutrient solution itself and/or water is preferred.

It will be apparent from Fig. 1 that because of the position of the entry portion 1 6 of the path 14, the boom 46 has to have an oscillatory motion.

Alternatively, there could be a closable gap in the entry portion 1 6 for the outer manifolds 44 to pass through. Fig. 3 shows an alternative arrangement in which the elevator 24 is arranged inside the enclosure, next to the helical path 14.

The entry portion 1 6 is then at the bottom of the unit, and if it possible for the boom 46 to rotate continuously in one direction, as long as it is synchronised so as not to foul the elevator 24.

However, this arrangement does not have the advantage of having the elevator 24 outside the enclosure.

Fig. 6 shows an alternative arrangement of the helical path 14. Instead of the path being a continuous downward slope, the racks 22 are for the most part horizontal (with the varying spacing an explained above) and only small portions 50 in the vicinity of the entry and exit portions slope in order to join one level of the next. This arrangement introduces only a small complication to the mechanical handling system, while ensuring that the spray nozzles 42 are at the most effective level in relation to the corresponding racks 22 for most of the travel of the nozzles. The portions 50 may be removable when the system is not in use, to permit easier access to the centre of the helical path 14 for maintenance and cleaning.

Fig. 7 shows diagrammatically how travelling spray nozzles may be adapted to a more conventional unit in which separate, horizontal, rectangular, racks 22 are arranged in a vertically spaced array. As previously, the spacing between some adjacent pairs of the racks 22 is less than between others, with a gradual increase in spacing from the top to the bottom of the array. The seedbed trays 32 are arranged on the racks 22 with newly germinating seeds in the racks with the smallest spacings and as the growth of the crops proceeds the trays are transferred manually to racks with gradually increasing headroom. This gives a much increased efficiency in utilisation of the space available.Although in Fig. 7 the racks with the largest headroom are shown at the bottom, this is not essential and the differing spacings may be otherwise arranged if desired or the racks can be contra sloping as shown in Fig. 10.

A rail 52 is arranged along the ceiling of the enclosure, and a vertical nutrient solution distribution manifold 44 is driven backwards and forwards along this rail by a hydraulic motor 54.

Nutrient solution and/or water is delivered to the manifold 44 and drives the motor 54 by a flexible hose 56. As before, the nutrient solution is taken from a sump in which the circulating solution coliects, via a suitable pump. As previously, the pump can be of smaller capacity than in previously known units. From the distribution manifold 44, the nutrient solution in sprayed over the trays 32 holding the growing crop through generally horizontally directed spray nozzles 42. The vertical spacing of these nozzles 42 again varies gradually from top to bottom of the manifold, to broadly correspond to the vertical spacings of the racks 22.

Fig. 8 shows a somewhat similar arrangement, except that the rail 52 is arranged along the floor of the enclosure rather than along the ceiling.

Aiternative arrangements are also possible, in which the manifold 44 is guided by rails both on the floor and the ceiling and/or the walls of the enclosure.

There is no need for the racks 22 to be purely rectangular as shown in Fig. 7. Particularly in large hydroponic units, the racks may be arranged in a path of any shape, including the helical shape described earlier or for example, a sinuous path so as to make maximum utilisation of any given area.

In such as case, one or more rails 52 can follow respective desired paths to give the best spray pattern around the trays 32, as shown by way of example in Fig. 9. Each rail then has a manifold 44 which may be driven along the rail by a hydraulic motor 54 driven by the hydroponic solution itself, as in Fig. 7 and Fig. 8, or alternatively the rail 52 may be in the form of a trough communicating with the sump and containing nutrient solution. In the latter case, the manifold 44 is suitably provided with an integral pump and motor which serves both to translate the manifold along the path defined by the trough, and also to scoop up nutrient solution from the trough and spray it from the nozzles 42. The pump and motor can be pneumatically operated.

Fig. 10 shows an alternative arrangement of racking wherein the racks are arranged in a contra sloping pattern. That is, each rack 62 slopes in the opposite direction to those above and below it.

The trays with seed are placed at the top narrowest section 57 of each rack and are moved and/or travel to the bottom widest section of the rack spacing 58 as the crop grows. One or more nutrient distribution manifolds 59 are mounted at fixed positions on or adjacent to the racking and are driven in an oscillatory and/or rotary motion substantially about or parallel to the axis of the manifold by motor 60. The motor 60 may be electric or pneumatic but a hydraulic motor operated by the nutrient solution itself and/or water is preferred. The manifold 59 has spray nozzles 61 formed in it or mounted on it so arranged as to spray nutrient solution and/or water over the seed-bed trays. The vertical spacing of these nozzles 61 varies generally to correspond with the vertical spacing of the rack adjacent to the manifold. It has been found that nozzles giving a fan-shaped spray, e.g. with an approximately 900 spread in a generally horizontal plane, coupled with oscillatory motion also generally in a horizontal plane, gives efficient nutrient/water distribution with a minimum number of manifolds. Such a fan-shaped spray is also preferable in the various other embodiments shown in Figs. 1 to 9.

In a further alternative arrangement of all the above versions of this invention the seed-bed trays may be replaced by sheet material in substantially flat form arranged in separate sheets or as a continuous sheet or belt for use by one or a plurality of crops.

Claims (14)

1. Hydroponic apparatus comprising a rack or racks for holding seed-bed trays, arranged in or for arrangement in an enclosure, and one or more spray nozzles arranged to spray a hydroponic nutrient solution and/or water over the seed-bed trays when in the racks, characterised in that drive means is provided, arranged for moving the nozzle(s) so as to successively spray different areas of the seed-bed trays.

2. Hydroponic apparatus according to claim 1, wherein the drive means is arranged to rotate or oscillate the nozzle(s) about a generally vertical axis.

3. Hydroponic apparatus according to claim 2 wherein a plurality of racks are vertically spaced and a plurality of vertically spaced spray nozzles are formed in or mounted on a nutrient solution distribution manifold which is arranged for rotation or oscillation about the generally vertical axis.

4. Hydroponic apparatus according to claim 2 or 3 wherein the nozzle or nozzles is/are each arranged to give a fan-shaped spray, so that the oscillation or rotation causes corresponding oscilation or rotation of the area covered by the fan.

5. Hydroponic apparatus according to any one of the preceding claims wherein the drive means is arranged to translate the nozzle(s) along the rack or racks.

6. Hydroponic apparatus according to any one of the preceding claims wherein there are a plurality of vertically spaced racks, and a plurality of vertically spaced spray nozzles is provided, each of which is movable in a generally horizontally plane by the drive means.

7. Hydroponic apparatus according to claim 6 wherein the vertical spacing of the racks varies from one adjacent pair of racks to another, and the vertical spacing of the nozzles also differs.

8. Hydroponic apparatus according to any one of the preceding claims wherein there are a plurality of vertically spaced rack portions and the spacing between one rack portion and the rack portion above it varies along the length of the rack.

9. Hydroponic apparatus comprising vertically spaced rack portions for holding a plurality of seed-bed trays along the length thereof, characterised in that the spacing between one rack portion and a rack portion above it varies along the length of the rack.

10. Hydroponic apparatus according to claim 9 wherein alternate racks slope by different amounts.

11. Hydroponic apparatus according to claim 10 wherein alternate racks slope in opposite directions.

12. Hydroponic apparatus according to claim 9 wherein the vertical spacing between one or more adjacent pairs of rack portions differs from that beween one or more others, and the apparatus is characterised in that the racks form a continuous path, successive points along which are vertically spaced from each other.

1 3. Hydroponic apparatus according to claim 12 wherein the path has a helical form.

14. Hydroponic apparatus substantially as any described herein with reference to the accompanying drawings.