FORM - 2
THE PATENTS ACT, 1970
(39 OF 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2006
COMPLETE SPECIFICATION
(See Section 10 and Rule 13)
TITLE OF INVENTION IMPROVED GREEHOUSE
APPLICANTS
MAHINDRA & MAHINDRA LTD., a Company Registered under the Indian Companies Act, having office at 1913, having its Registered office at Gateway Building, Apollo Bunder, Mumbai - 400001 (Maharashtra).
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed:

Field of the invention
The present invention relates to cost effective naturally ventilated greenhouses with enhanced structural stability to withstand forces due to high wind flows.
Background and prior art
Over several decades efforts have been to provide greenhouses in the form of a canopy for controlled environment with appropriate ventilation, temperature, structural stability to withstand excessive wind forces, to facilitate the higher productivity in horticultural and agricultural practices. The heavy duty structures of greenhouses presently in use result in high cost constructions which are not desirable.
US 919,673 relates to ventilators for greenhouses disclosing a novel mechanism by which the swinging sashes on each side of the greenhouse roof may be operated either simultaneously or independently from a single shaft. Further the invention also provides for a construction in which allows for the locking of the sashes in their open or closed positions.
US 3,028,872 relates to light weight greenhouses that can be constructed and easily transportable by hand labour. The construction allows to achieve substantially accurate shape in cross section and having a body comprising a main framework covered with flexible transparent sheet material, one part of the frame being secured between adjacent portions of the main framework so that another of the frame, due to their natural resilience of the frame, tends to take up a position outwardly of the accurate shape of the adjacent portions thus providing a ventilating opening between said portions, and retaining means to control the position of the said other part and operable to bend the frame to said accurate shape to close the ventilating opening.
WO 2005/029941 discloses an inexpensive greenhouse vent which is achieved by using a bendable vent panel at the apex of a glazed greenhouse roof and fastening a central portion of the vent panel to a ridge at the apex and bending and bowing opposite sides of the vent panel upwardly or downwardly between the closed and open venting positions. A larger air flow and larger vent opening are achieved when using a raised ridge located above the roof glazing panels and bowing the sides of the vent panel down to a closed position and bowing the sides of the vent panel

upwardly to an open position. An actuator for flexing ends of the panel between the closed position to close the vent opening and the open venting position allows air flow into or from the interior of the greenhouse. A gutter may be provided on the raised ridge to collect water infiltrating between overlapped, corrugated ends of adjacent vent panels. Other gutters may be provided on a vent rail and vent header to discharge water into a drain channel that also collects water discharging from the ridge gutter with the drain channel carrying the water down to discharge into a main gutter for the greenhouse. The vent header, vent rail and vent panels may be preassembled together on the ground and raised into position and attached to the greenhouse frame members. Then, the vent rails and vent headers may be detached from one another to allow raising of the vent rails from the vent headers which results in a bending of the vent panel to its open position.
Typically these greenhouses disclosed in WO 2005/029941 vary from 20 feet to 40 feet in width. The roofs are usually supported by columns varying in height from 10 to 14 feet. The roof support usually comprises structural arches usually bent to a radius of about 12 feet to 25 feet. These curved rafter supports are usually round tubes of about 1.5 to 3 inches in diameter. Typically, the translucent or transparent glazing panels supported on this curved structural support are about four to six feet wide panels which are longitudinally corrugated extending up to thirty-nine feet in length. Such a construction is complex with several moving parts controlled by actuators needing adjustments and frequent servicing and maintenance protocols which could be difficult to achieve in rural areas.
The current greenhouses require heavy duty high-cost structures to withstand wind forces on its structural members. Further several greenhouses in the prior art have actuators with moving parts that need to be operated manually or electronically to adjust the ventilation in the greenhouse. Such controls modulate the ventilation but do not help to reduce the impact of high wind forces on the greenhouse structure.
There is therefore a need to provide low cost structural configurations that reduce the impact of high wind loads on the greenhouse structure without needing constant maintenance and yet providing appropriate ventilation, temperature and volume of air inside the greenhouse needed for plant growth.

Objects of the invention
The main object of the present invention is to provide low cost light structural configurations for aerodynamic green houses that can withstand wind forces and yet provide adequate ventilation, temperature and volume of air required for plant growth.
Another object of the present invention is use of light weight structural members of such cross-section that they have the optimum capacity to simultaneously withstand buckling, bending and torsional forces. It is yet another object of the invention to provide support and grip to the workmen during assembly and servicing operations of the said greenhouses.
It is yet another object of the invention to provide appropriate joining means for the structural elements of the said greenhouses.
It is yet another object of the invention to provide structural options in the said greenhouses to enhance modularity with respect to the coverage areas and/or to meet evolving field conditions.
Detailed description of the invention
With the above objects in view and other objects as will appear hereinafter the present invention provides light weight aerodynamic greenhouse structural configuration with larger bay-widths compared to its roof height wherein a two-way ventilator system caters the higher ventilation needs of the said wider bay, characterised by free flow of wind from wind side to the leeward side at least for the outer bays facing the wind in a multi bay greenhouses.
The improved aerodynamics is achieved by simultaneous reduction in the slope of the roof and increase in bay width wherein the ratio of the roof height to the bay width is 0.1 -0.25.
The greenhouse of the present invention provides appropriate roof slope to ensure sufficient rain water flow.
The ratio of bay height (H) / bay width (W) in current naturally ventilated, gutter connected, multi-span greenhouses are in the range 0.55 - 0.8 wherein the (W) is 6 -10 meters and (H) is 3.5 - 7 meters.

The present invention discloses greenhouses with preferably ratio of H/W of 0.3 -0.5 wherein the bay width (W) is 11 - 20 meters and bay height (H) is 5 - 8 meters.
A typical configuration of a greenhouse of the present invention is bay width (W) of 16 meters and bay height (H) of 6 meters.
Various embodiments of the greenhouses of the present invention achieves the desired aerodynamics as follows::
• The outer bays with 2-way ventilators and inner bays are provided with one way ventilators.
• The outer bays are provided with one way ventilators while the inner bays are provided with 2 way ventilators.
In certain embodiments of this invention, the height of the outer sides of green house may also be reduced to further improve the aerodynamics of the greenhouse.
Vertical sides at the front and rear ends of the bays may also be made sloping in order to reduce the wind forces on the front and rear ends of the greenhouse.
The constructional features of the embodiments of the present inventions are disclosed and described with reference to the accompanying drawings. It is understood that the said embodiments are shown and described by way of illustration only and do not limit the scope of the invention.
Brief description of the drawings
Figure 1 is a view of greenhouse having wider bays with two-way raised ridge
ventilators showing the two vent- openings and the two side ventilators with rolling
curtain. Figure 1a shows the additional structural features. Fig 1 b shows the
stability result of the FEA of the structure as per Fig 1a.
Figure 2 shows the front profile of the outer bay of a greenhouse according to the
present invention. The front profile shown by dotted lines represent the outer bay of
a greenhouse according to the prior art
Figure 3 shows the front profile of a greenhouse having lowered outer side roof and
an inclined central roof

Figure 4 shows a greenhouse having a middle wider bay with raised ridge two way
ventilator flanked on either side by bays of reduced height and outer side roof slope
having one way ventilator.
Figure 5 is an isometric partial view of the raised ridge two way ventilator showing a
fixed barrier and the diverted air flow from the wind side to the leeward side.
Figure 6 is a cross section of a two way raised ridge ventilator provided with a
hinged barrier showing its operation when high velocity air flow deflects it and flows
out through the opposite opening.
Figure 7 is a cross section of a two way raised ridge ventilator provided with a
flexible barrier.
Figure 8 and 8A is a partial view of a greenhouse structure with covering material
removed to expose the structural details.
Figure 9 is an isometric view of a T joint showing the arc shaped strips around it.
FigurelO is an isometric view of a pipe end joined to a pipe.
Figure 1 shows an embodiment of the present invention that provides a light weight aerodynamic greenhouse with larger bay-width compared to its roof height, wherein a two-way ventilator system provides higher ventilation .The three bay greenhouse shown in figure 1 comprises wider bays 1,2 and 3 that are provided with 2-way raised ridge ventilators having openings 7 and 8,formed by the outer side roof 4, the inner side roof 5 both having reduced slope and the raised ridge roof 6. The outer bays 1 and 3 are provided with corridors and side ventilators. The outer bay 1 is provided with corridor 9 and side ventilators 10 controlled by rolling curtain 11 by means of handle 12. Gutters 13 are provided between bays. Further as depicted in Figure 1a an intermediate column 21 is provided along with strut 22. A tension member 23 is provided to reduce the deflection at the upper end of column 11.
In one of the embodiments the greenhouse is provided with 2-way raised ridge ventilators wherein the outer bay is provided with a corridor and side ventilators and the outer side of the outer bay is made more aerodynamic by lowering the inner side of outer roof and outer side of the ridge roof as shown in figure 3. The inner bays may be of the same ridge height or more than the outer bays.

The embodiment in Figure 4 shows a multi bay greenhouse with combination of outer bays of smaller width provided with one way ventilators and the wider inner bays provided with 2-way raised ridge ventilators wherein, the outer roof slope of the outer bays is reduced.
For improved aerodynamics and to reduce the impact of the wind forces on the greenhouse structure, a two way 'raised ridge ventilator' of the present invention has raised ridge in the roof to form openings for ventilation. Two-way ventilation is superior to one-way ventilation as it offers provisions for changing wind direction.
Figure 5 shows the 2 way ventilator formed by the two side roofs 14 and 15 and the raised ridge roof 16 inside which is fixed the barrier 17 The flow of wind into the bay and out of it, providing the ventilating function is shown in dotted lines. The raised ridge ventilator of the present invention is open on both sides and allows wind to pass right across from one opening to the other. There is direct flow of air across the ventilator from windward side to leeward side which creates a partial vacuum below the flow, generating a ventilating action. However at very low wind speeds, ventilation may not be satisfactory and may not reach plant level. To resolve this problem, in one of the embodiments of the present invention, a barrier or deflector may be introduced across the air flow to deflect the air into the greenhouse and then allow the displaced air to flow out through the leeward opening.
In one of the embodiments of the present invention, a ventilator with wind barrier may be employed for the inner bays, and ventilator without barrier may be employed at the outer bays that directly face the wind. Such a configuration has the advantage of offering relatively less resistance to wind flow, with the consequence of reducing the wind load on the greenhouse structure.
In another embodiment shown in figure 6 the barrier 18 may be hinged to the ridge instead of rigidly fixing it, whicti would deflect only at high wind speed and offer less resistance to wind speed. Means such as springs may be used to control or cushion deflection movement in place of or in addition to the gravity control.
In another embodiment shown in figure 7, the barrier 19 can be made of flexible material like cloth or plastic sheet, the upper end of the barrier being fastened to the

ridge. To hold the cloth or sheet taut, a rod 20 or any member or members may be fixed to the bottom of flexible barrier. In such a configuration no hinge(s) is required.
Advantage of the deflecting barrier ventilator is that, it can also be used for outer bays facing wind, which will deflect low speed winds into the greenhouse providing ventilation and allowing high speed wind to pass across, thereby reducing wind forces on the greenhouse structure.
In an embodiment, a net or semi-permeable barrier may be provided in place of the fixed or the hinged barrier.
Bays of a greenhouse comprise several frames equally spaced one behind the other and joined together by purlins and gutter to form a rigid structure, the frames comprising columns, roof members, trusses
The wider outer bay shown in figure 8 A is formed by 3 columns - the central or ridge column 21, the outer column 22 and struts and the gutter column 23. The roof with the raised ridge ventilator comprises the central arc 26, outer arc 27 and the inner arc 28 supported on the said columns by struts 29 and 30, and bolted joints/brackets. A slant corridor member 25 propped by tie bar 24 forms the corridor of the greenhouse which supports the side ventilator with rolling curtains. The columns and the roof members are additionally strengthened by struts 33, 31 and chord 32 as shown therein to withstand the wind load. Figure 1 shows such 4 frames equi-spaced one behind the other joined together by purlins 35,36,37, 38 and 39.
Figure 8 A also shows the front corridor formed by slant members 41 propped up by tie bar 42 and purlin 34.The columns are further strengthened by tension members 43 and 44 fixed to their upper end portions. Gutter 40 is provided between the outer bay and the adjacent inner bay.
Such a configuration exhibiting far less resistance to wind flow with the further advantage of ensuring free air flow across the roof ventilator, thereby reducing wind loads on the structure, enabling such a configuration to use fewer and lighter members in the greenhouse for a given covered area as compared to the greenhouses of the prior art.

While reduction in the wind loads as above allows the use of fewer and/or lighter and low cost members for the structure by reduction in the cross sectional area, preference may need to be to the use of thinner pipes or tubes of higher diameter in case of round-type, and height and width in case of rectangular or square pipes than thicker but slender pipes in order to optimize their capacity to withstand buckling, bending and torsional loads, and also to facilitate assembly and service personnel/ workmen to get better hold and support while climbing on the said pipes/ structures. However, prevalent joining/ jointing systems for assembly of greenhouses are not appropriate for use with thin walled pipes of standard diameter or height and width.
Prior art provides for 'L1 and T joints for pipes, wherein, L or T shaped insert are used for joining with bolts 2 or 3 pipes respectively. The insert is fabricated by welding pipe pieces of one standard size lower than the standard size of the pipes to be joined.
In one of the embodiments of the present invention use of flat arc shaped strips 46 of the required radius are welded or riveted around the insert of a T-joint 45 as shown in Fig. 9. These strips may be formed by cutting off slices from the pipe of the same diameter as the insert, cutting them in 2 pieces and appropriately flattening them to match the outer diameter of the insert.
Inserts of similar construction may be employed for straight joints or joints of any other angle between two pipes to provide strength to the joint.
In yet another embodiment, separate pipe ends 47 prepared from thicker pipes of one standard size lower are inserted in the ends of the said pipe 48 and bolted together to provide stronger joining ends to the thinner pipe as shown in Fig. 10. It is understood that sleeves of one standard size larger pipe may be employed to form a female joining sleeve, having the arc shaped strips welded to the inside wall of the sleeve.
The structural stability of the said aerodynamic greenhouse structure depicted in Figure 1a of the present invention to sustain dead, live and wind load is investigated using finite element method. The results are provided in Figure 1b. The objective and scope is to investigate the structural stability of the greenhouse structure of the

present invention in terms of estimation of the forces in each of the members and its resilience to withstand the force.
Following are the input load details:
The Dead Load comprising self-weight of the structure
Live Load is due to 'Plants' hung from the frame and occasional labour that
would climb on the frame. It is considered and estimated for this particular
analysis as 0.20 + 0.125 = 0.25 KN/m2.
Wind Load is calculated based on the assumed velocity of 150 KM/Hr
Figure 1b depicts results of the investigation of the finite element analysis. It is observed that the inclined member 13 has the maximum stress value of 742.4 N/mm2 in the maximum load conditions. It is within the acceptable limits in the context of resilience and less than about 14% than the greenhouse structure that does not use the synergistic combination of the strut 22 and tension member 23 of the present invention. It is to be noted that the deflection of the node for the said stress level in the structure of the present invention is 45.3. There is about 32% reduction in the deflection than the greenhouse structure that does not use the said structural synergistic configuration and indicates the structural stability of the greenhouse structure of the present invention.

We Claim
1. An improved greenhouse comprising
a two way ventilator system comprising raised ridge ventilator/s provided with
openings (7, 8) formed by the outer side roof (4), inner side roof (5) having
reduced slope and the raised ridge roof (6);
an intermediate column (21) provided along with strut (22);
a tension member (23) to reduce the deflection at the upper end of column
(11);
outer bay/s (1,3) provided with corridors and side ventilator/s wherein one of
the outer bays (1) is provided with corridor (9) a.nd side ventilator (10)
controlled by rolling curtain (11);
gutter/s (13) provided between bay/s.
2. An improved greenhouse as claimed in claim 1 wherein the outer bay/s are
provided with side ventilator/s.

3. An improved greenhouse as claimed in claims 1, 2 wherein the outer bay is
provided with a corridor and side ventilators,
outer side of the outer bay is made by lowering the inner side of outer roof and outer side of the ridge roof wherein the inner bays may be of the same ridge height or more than the outer bays.
4. An improved greenhouse as claimed in claims 1-3 comprising multiple bays with a combination of outer bays provided with one way ventilators and the wider inner bays provided with 2-way raised ridge ventilators wherein, the outer roof slope of the outer bays is substantially reduced.
5. An improved greenhouse as claimed in clairns 1-4 comprising a two way raised ridge ventilator provided with a raised ricjge in the roof to form openings for ventilation.
6. An improved greenhouse as claimed in clairns 1-5 comprising a barrier to deflect the air into the greenhouse and then allow the displaced air to flow out through the leeward opening.
7. An improved greenhouse as claimed in claims 1-6 wherein a ventilator with wind barrier is provided for the inner bays, ventilator without barrier is employed with advantage at the outer bays that directly face the wind.
8. An improved greenhouse as claimed in claims 1-7 wherein the barrier (18) is hinged to the ridge.
9. An improved greenhouse as claimed in claim 6 wherein spring is provided to cushion deflection movement.
10. An improved greenhouse as claimed in clairns 1-9 the barrier is a flexible material such as cloth, plastic sheet, sheet taut
wherein upper end of the barrier is fastened to the ridge,
a member such as rod (20) is fixed to the bottom of the said flexible material.

11. An improved greenhouse as claimed in claims 1-10 wherein a net or semipermeable barrier is provided.
12. An improved greenhouse as claimed in claims 1-11 wherein bays comprise plurality of frames equally spaced one behind the other and joined together by purlins and gutter to form a rigid structure wherein
the frames comprises of columns, roof members .trusses.
13. An improved greenhouse as claimed in claims 1-12 wherein the wider outer bay is formed by a central column (21), outer column (22), struts & gutter column 23.
14. An improved greenhouse as claimed in claims 1-13 wherein the roof is provided with the raised ridge ventilator comprising
Central arc (26), outer arc (27), inner arc (28) supported on columns by struts
(29) and (30);
bolted joints/brackets;
a slant corridor member (25) propped by tie bar (24) to form a corridor of the
greenhouse that supports the side ventilator with rolling curtains;
the columns and the roof members strengthened by struts (33, 31) and chord
32 to withstand the wind load.
15. An improved greenhouse as claimed in claims 1-14 wherein
the front corridor is formed by slant members (41) propped up by tie bar (42)
and purlin (34);
the columns are further strengthened by tension members (43, 44) fixed to
their upper end portions ;
gutter (40) is provided between the outer bay and the adjacent inner bay.
16. An improved greenhouse as claimed in claims 1-15 wherein
flat arc shaped strips(46) of the required radius that are welded or riveted around the insert of a T-joint (45).
17. An improved greenhouse as claimed in claim 16 wherein the strips are formed by cutting off slices from the pipe of the same diameter as the insert, cutting them in 2 pieces and flattening them to match the OD of the insert.
18. An improved greenhouse as claimed in claims 1 -17 wherein
separate pipe ends (47) prepared from thicker pipe pieces of one standard size lower are inserted in the ends of the pipe (48) and bolted together to provide stronger joining ends to the thinner pipe.
19. An improved greenhouse as claimed in claims 1-18 wherein, the bays provided with two way raised ridge ventilators have the ratio of roof height to bay width in the range of 0.1-0.25.
20. An improved greenhouse as claimed in claims 1-19 wherein height (H) to width (W) ratio is in the range of 0.3 - 0.5 wherein the bay width (W) is in the range of11 - 20 meters and bay height (H) is in the range of 5 - 8 meters.

21. An improved greenhouse as claimed in claims 1-20 wherein outer bays are provided with two way ventilators and inner bays are provided with one way ventilators.
22. An improved greenhouse as claimed in claims 1-21 wherein the outer bays are provided with one way ventilators while the inner bays are provided with 2 way ventilators.