CLIAMS:We Claim:

1. A light weight greenhouse with enhanced structural stability to withstand forces due to high wind flows having multi-bays provided with one-way ventilators with openings formed by upper roofs (9, 14) and lower roofs (10, 13), wherein the said upper roofs (9, 14) are characterised by reduced slope angles (theta) in the range of 100 to 250.

2. The light weight greenhouse as claimed in claim 1, wherein outer bays (Bo) are provided with inclined side wall/corridors (7, 8) and side ventilators (SV).

3. The light weight greenhouse having multi-bays, provided with one-way roof ventilators, wherein the outer bays (Bo) are provided with side ventilators (SV) and have at least ridge height less than that of the inner bays (Bi) or at least outer side roofs of reduced slope less than that of the inner bays (Bi) and roof ventilators (RV) of the outer bays (Bo) are facing inwards.

4. The light weight greenhouse as claimed in claim 3, wherein the outer side roof slope angle is in the range of 100 to 250.

5. The light weight greenhouse as claimed in claims 1 to 4, wherein, the said outer bays (Bo) have ratio of roof height to bay-width in the range of 0.1 to 0.25.

6. The light weight greenhouse as claimed in claims 3 and 4, wherein, ratio of roof height to roof width of outer side roof of outer bay (Bo) is in the range of 0.15 to 0.45.

7. The greenhouse having multi-bays and columns supporting gutters, wherein an intermediate column is provided to support outside roof of outer bay(s) in addition to outer column and gutter column.

8. The light weight greenhouse as claimed in claims 1 to 6, having multi-bays, wherein an intermediate column (5, 6) is provided to support the outside roof (9, 14) of the outer bay (Bo) in addition to the outer column (1, 4) and the gutter column (2, 3).

9. The light weight greenhouse as claimed in claim 8, wherein link member(s) (15, 16) is(are) provided between the said intermediate column (5, 6) and the said outside roof (9, 14).

10. The light weight greenhouse having multi-bays according to claim 1 and 2, comprising lower roofs (10, 11, 13) and upper roofs (9, 12, 14) of said reduced slope, outer columns (1, 4), inner / gutter columns (2, 3), corridor members (7, 8) and intermediate columns (5, 6).

11. The light weight greenhouse according to claim 3, comprising outer bays (Bo) of said less ridge height and roofs (26, 27) of said reduced slopes compared to the roofs (28, 29) of the inner bays, wherein the outer bays are also provided with side ventilators (SV) supported by inclined corridor members (25, 30).

12. The light weight greenhouse as claimed in claims 10,11, wherein front / back corridor (C) is formed by slant members (45, 48, 51, 54) propped up by tie bar (46, 49, 52, 55) and front purlin (63).

13. The light weight greenhouse as claimed in claims 10 to 12, wherein tension members (58, 59) are provided between adjacent columns fixed to their upper end portions for further strengthening structure.

14. A method to withstand forces due to high wind flows in a greenhouse by providing multi-bays having one-way ventilators with openings formed by upper roofs (9, 14) and lower roofs (10, 13), wherein the said upper roofs (9, 14) are characterised by reduced roof slope in the range of 100 to 250.

15. The method as claimed in claim 14, wherein outer bays (Bo) are provided with side ventilators (SV) of a multi-bay light weight greenhouse and wherein at least ridge height less than that of inner bays or at least roofs of said reduced slope less than that of the inner bays.

16. The method according to claims 14,15, of providing intermediate column between the outer column and the inner / gutter column of the outer bay for supporting outer roof.

Dated this 28th day of March, 2014

Dr. Gopakumar G. Nair
(Regn.No.: IN/PA 509)
Agent for the Applicant
Gopakumar Nair Associates ,TagSPECI:FORM 2
THE PATENT ACT 1970
(39 of 1970)
AND
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION:

“ LIGHT WEIGHT GREENHOUSE ”

2. APPLICANT:

(a) NAME: MAHINDRA & MAHINDRA LTD.

(b) NATIONALITY: A Company Registered under the Indian Companies Act
1913

(c) ADDRESS: Gateway Building, Apollo Bunder, Mumbai – 400001,
Maharashtra, India.

3. 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 one way 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 made to construct low cost greenhouses having structural stability to withstand excessive wind forces and at the same time provide controlled environment with appropriate ventilation, temperature, to facilitate higher productivity in horticultural and agricultural practices. The heavy duty structures of greenhouses presently in use result in high cost which is not desirable.

The cost per square meter of covered area is considerably more for larger multi-bay gutter-connected greenhouses of covered area of 500 m2 or more. This is because of the higher ridge heights needed to keep the temperature of the inner bay(s) low which do not have the proximity to the side ventilators. In this context, therefore, the term ‘multi-bay’ will hereinafter be used for greenhouses having at least one inner bay which means a greenhouse having at least 3 bays including the two outer bays and the term “outer bay” used for the two outermost bays on either side of the inner bay(s).

The ridge height or the overall bay heights and the roof slopes associated with the current greenhouses cause high wind loads on the greenhouse structure for a given wind speed, needing heavy duty structures to withstand the wind loads.

There is therefore a need to provide low cost structural configurations that reduce the impact of high wind loads on the greenhouse structure 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 greenhouses that can withstand wind forces corresponding to the rated wind speeds and yet provide adequate ventilation, temperature and volume of air required for plant growth. Conversely, the object is also to provide structural configuration of greenhouse to enhance its capacity to withstand wind forces.

Another object of the present invention is to provide cost effective structural solutions of strengthening the greenhouse against wind loads.

SUMMARY OF INVENTION:

The present invention discloses a light weight greenhouse with multi-bays having one-way ventilators formed by the opening between the lower roof and the upper roof of reduced slope.

In an embodiment, upper roofs are characterised by reduced slope angles in the range of 100 to 250, and / or reduced ridge-height applied to selective, or specifically only to the outer side bay(s), compared to inner bay(s) that have normal / conventional slope angles and / or normal ridge height.

BRIEF DESCRIPTION OF THE DRAWINGS:
FIGURE 1 shows front profile of the outer bay of a greenhouse according to the present invention. The front profile shown by dotted lines represents the outer bay of a greenhouse according to the prior art.

FIGURE 2 shows a line diagram of an interior frame of a three-bay greenhouse having bays of reduced roof slope and having outer ventilators facing inwards.

FIGURE 3 is a line diagram of an interior frame of a four-bay greenhouse having the outer bays of reduced ridge height and the outer roofs of reduced slope than the inner bays. It also clarifies notations HB, HR, WB, WR, and ‘theta’.

FIGURE 4 is an isometric partial view of the greenhouse according to FIGURE 3 with a portion of polyfilm shown cut away exposing the structural members.

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 to reduce wind loads on the structure, comprising the roofs of reduced slope and / or in some instances, the bays of reduced ridge-height, to ensure reduction of wind force on greenhouse structure and at the same time the maintenance of temperatures and other agronomic requirements inside the greenhouse, in the various embodiments disclosed here below and the methods of providing the above features. In the context of curved roof, by the slope of roof is meant the mean slope averaged over its width.

In one embodiment, the greenhouse structural configuration provides multi-bays having one-way ventilators formed by the opening between the lower roof and the upper roof of reduced slope.

The improved aerodynamics is achieved by reduction in at least the slope of the roof or at least the ridge height of the bay.

The agronomic performance of a multi-bay greenhouse can be improved further by employing some unique features in structural configuration of greenhouse.

One such feature is restricting the changes for improved aerodynamics of reducing the roof slope or the ridge height or both to only the outer side bay(s) compared to inner bay(s) which (inner bays) are subjected to relatively less wind forces than the outer bays by the “shielding effect” and hence can be allowed to have their ridge height, ventilator height and/or roof slopes more as per the agronomic needs. Also, the outer bays provided with side ventilators have the advantage of greater proximity to the side ventilation, making it possible to keep the temperature therein low in spite of reducing the slope and / or ridge height of the outer roof thereof.

Secondly, the inner bay(s) can be allowed to have any bay-width, ridge height and ventilator height as desirable or required for plant growth.
Thirdly, the outer bay(s) can be provided with one-way ventilator oriented inwards, outer side roof of reduced slope or reduced ridge height or both compared to the inner bay(s), and corridor with side ventilators.

In the context of outer side roof of outer bay, the ideal mean roof angle (theta) is less than or equal to 25o. This is based on the following considerations:- The I.S. code for design wind loads, I.S. 875 (part 3) gives lowest pressure coefficient for roof slope angle of 300 for straight roofs with vertical side walls. Considering the curvature of curved roofs and the elongation of the poly film covering material and consequent bulging of the covering material by the negative pressure coefficients, roof angle of less than 250 provides better stabilizing effect ensuring minimum wind loads even at high wind speeds. Also, considering side wall / corridor inclination and the radius of curvature of curved roofs in the case of rigid or semi rigid covering material like polycarbonate sheets, the said angle stands reduced to about 200.

Considering the above factors and the minimum slope required for rain water flow, the range of roof angle can be between 10 0 - 250 or the ratio of outer side roof height (HR’) to roof width (WR) between the lower and upper end of the outer side roof can be in the range of 0.15 - 0.45 for reducing the wind loads.

The corresponding range of roof angles for current multi-bay greenhouses having one way ventilators is 270 - 330.

Where slope is reduced, the outer roof width can be increased to any value till the ridge height of outer bay is less than or equal to the ridge height of inner bay(s).

Where only the ridge height of outer bay is reduced compared to the inner bay(s), the reduction has to be substantial, say 250 mm.

The reduction in roof slope is constrained by many factors like the width of the bay, minimum roof ventilator height permissible and radius of curvature of the roof. In the event of the above factors becoming critical, the present invention provides remedial means by shifting the roof vent opening away from near the vertical centreline of the bay towards the inner side as required, thus increasing the height of vent opening in spite of the reduced slope of outer roof as is clear from Figures 1 and 3.

The greenhouse of the present invention provides appropriate roof slope to ensure sufficient rain water flow.

The height of the outer sides of greenhouse 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.

Thus, various further embodiments of the greenhouse of the present invention achieving the desired aerodynamics / agronomics can be constructed as described in detail with reference to following drawings.

The constructional features and the methods of providing these 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.

Figure 1 illustrates the underlying feature of the present invention. In Figure 1, the front profiles of the current multi-bay greenhouse are shown in dotted lines and the multi-bay greenhouse according to the present inventions in continuous line superimposed on each other for comparison. It is clear from Figure1 that the roof slopes for present invention are less steep than those of current greenhouse. The ridge height of present greenhouse may be equal to or less than that of the conventional greenhouse. The effect of increasing the bay-width with respect to the height in reducing the roof slopes is illustrated in line diagram of Figure 1. The bay width of the present greenhouse may be increased to attain the required ridge height. A more detailed configuration of an embodiment of multi-bay greenhouse according to the present invention is shown in the line diagram of Figure 2.

Figure 2 shows a three-bay greenhouse provided with one-way ventilators, the outer ventilators facing inward in order to offer minimum resistance to wind flows in both directions. The configuration shown constitutes one frame of the greenhouse comprising outer columns 1 and 4, inner columns 2 and 3, corridor members 7 and 8, upper roof members 9, 12 and 14, and lower roof members 10, 11 and 13. The outer roof members 9 and 14 are additionally supported by intermediate columns 5 and 6 respectively to enhance the capacity of the greenhouse structure to withstand wind loads. The frame also comprises a number of smaller link members as shown for rigidity and strength. Many such frames spaced certain distance apart depending on the length of the greenhouse and inter connected by purlins complete the greenhouse structure. Corridors may be provided at front and back also of greenhouse. 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 etc.

In another form of the present invention, Figure 3 and 4 show an embodiment, wherein the outer bays of a four-bay greenhouse are provided roofs of reduced roof slope angle (theta) and reduced ridge height (Hb1) than the inner bays, and also provided with side ventilators as is clear in the line diagram of Figure 3 of an interior frame of the present greenhouse.

Figure 4 shows part of a complete greenhouse as per the said another form of the present invention with a portion of the poly film shown cut away to expose the internal structural members of the outer bay and the inner bay next to it. Frames similar to Figure 3 are shown spaced one behind the other and are joined by purlins and gutters to form the greenhouse structure.

Referring to Figure 4, 21 is an outer column of one typical frame; 22, 23, are inner columns supporting gutters (56, 57), 24 is intermediate column between the outer and the gutter column, 25 is inclined corridor member, 26 is upper roof member and 27 is lower roof member of the outer bay, and 28, 29 are upper and lower roof members of the inner bay next to it.

Additional members employed for the construction of the greenhouse structure include members 30, 31, 32, 33, 34, 35, 36 and 37. Tension members in the form of steel ropes 58, 59 are employed for holding the columns together limiting their deflections at the upper ends.

The four frames (F1, F2, F3, F4) shown are joined by purlins 38, 39, 40 of the outer bay and purlins 41, 42, 43 of the inner bay and other purlins of the remaining two bays.

The inner bays of front and rear most frames (F1, F4) are provided with a central column (such as 47, 50) which supports the front corridor member (such as 48, 54) and tie bar or brace (such as 46, 49, 52, 55). Similarly 44, 45, 48 and 51 are other members forming the front corridor.

The covered portion of the greenhouse shows the poly film 60, rolling curtain 61 of the front side ventilator and the shown cut away end of the curtain rod 62.

Such a configuration exhibits far less resistance to wind flow thereby reducing wind loads on the structure, enabling such a configuration to use fewer and / or lighter structural members in the greenhouse for a given covered area as compared to the greenhouses of the prior art.

An effective way to strengthen the greenhouse structure against wind loads is to provide an intermediate column (24) supporting outer side roof of outer bay. The intermediate column (24) can be provided in the outer bay between the outer column and the gutter column to strengthen the outer side roof against the wind loads caused by at least the positive pressure coefficients or at least the negative pressure coefficients in any multi-bay greenhouse provided with gutter columns. The intermediate column can be inclined also.

It is further clarified that the intermediate column (such as 24) is provided for interior frames in addition to those between outer column and gutter column, or between adjacent gutter columns of the front-most frame and the rear-most frame of a greenhouse.
Figures 2, 3 and 4 show embodiments provided with such a strengthening arrangement wherein, the intermediate column (such as 5 and 6 in Figure 2) is provided to support the outer side roof along with a link member (such as 15, 16 in Figure 2, and 32 in Figure 4) from the said column to the roof to provide additional support.

In Figure 3, the intermediate column (such as 17) is shown at the centre of bay width. In another embodiment of Figure 2, it (5, 6) is located closer to the outer column. Link member(s) (such as 15, 16) between the intermediate column and the said roof may be provided in all cases.

Similarly, in any current multi-bay greenhouse having outer bay provided with columns to support gutters, an intermediate column to support the outer side roof thereof may be provided in addition to the outer column and the gutter column.

In another embodiment, a method to withstand forces due to high wind flows in a greenhouse is disclosed. The method comprises of providing multi-bays having one-way ventilators with openings formed by upper roofs (9, 14) and lower roofs (10, 13), wherein the upper roofs (9, 14) are characterised by reduced roof slope in the range of 100 to 250. Further, the method provides outer bays (Bo) with side ventilators (SV) of a multi-bay light weight greenhouse and at least ridge height less than that of inner bays or at least roofs of said reduced slope less than that of the inner bays.