CA1244242A - Methods and apparatus for preventing or retarding fruit and vegetable freezing - Google Patents
Methods and apparatus for preventing or retarding fruit and vegetable freezingInfo
- Publication number
- CA1244242A CA1244242A CA000445751A CA445751A CA1244242A CA 1244242 A CA1244242 A CA 1244242A CA 000445751 A CA000445751 A CA 000445751A CA 445751 A CA445751 A CA 445751A CA 1244242 A CA1244242 A CA 1244242A
- Authority
- CA
- Canada
- Prior art keywords
- tower
- rotor
- ground
- blades
- shaft
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
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- Catching Or Destruction (AREA)
Abstract
ABSTRACT
Apparatus is provided for protecting crops from frost damage in the form of a vertical tower fixed to the earth against gyration, a rotor on top with two airfoil blades extending upward at a conical angle and drive means drivingly connected to the rotor through a vertical shaft, said tower projecting substantially above the level of the trees to be protected and sufficient to pick up air in the inversion layer and deliver it to the ground in a generally cylindrical mass to spread out radially without substantial disturbance of the soil.
Apparatus is provided for protecting crops from frost damage in the form of a vertical tower fixed to the earth against gyration, a rotor on top with two airfoil blades extending upward at a conical angle and drive means drivingly connected to the rotor through a vertical shaft, said tower projecting substantially above the level of the trees to be protected and sufficient to pick up air in the inversion layer and deliver it to the ground in a generally cylindrical mass to spread out radially without substantial disturbance of the soil.
Description
l~f.~
The damaging freeæes which occur in the fruit and vegetable industries are a well known occurrence. rrh~se freezes are generally known to be due primarily to the formation oE
atmospheric inversions over a ~airly wide area. This condition normally occurs on clear, calm, cold nights and is chara¢terized ~y an atmosphere in which air temperature increases with altitude. Unfortunately, an inversion is an inherently stable condition which -tends to persist until wind velocities increase or until daybreak, at which time incoming solar radiation begins to warm the earth and trees.
The freezing of foliage and of the crop is purely a radiation phenomena, brought on by the inversion, in which the soil, foilage and fruit all radiate heat to space. The result is that the atmosphere cools from the ground upward. As a result, it is not uncommon to find temperature differentials of 10 or more between the ground and 60 foot levels above the ground.
The existance of this warm air mass at higher elevations represents a very large potential energy source which can be used to oEfset a grove's net radiation heat loss.
TherP have been many m~thods and apparatus proposed in an effort to solve this freeze problem. Perhaps, the best known and most time honored is the use of "smudge pots" scattered throughout the area to be protected. While these are somewhat effect ve, they fall far short of belng the real answer to the problem. It has also been proposed to use wind machines to create a sur~ace wind simulating that which, when it naturally occurs, reduces the freeze damage. Such machines are illustrated in Towt U.S. patent 2,481,702; Potter U.S. patent
The damaging freeæes which occur in the fruit and vegetable industries are a well known occurrence. rrh~se freezes are generally known to be due primarily to the formation oE
atmospheric inversions over a ~airly wide area. This condition normally occurs on clear, calm, cold nights and is chara¢terized ~y an atmosphere in which air temperature increases with altitude. Unfortunately, an inversion is an inherently stable condition which -tends to persist until wind velocities increase or until daybreak, at which time incoming solar radiation begins to warm the earth and trees.
The freezing of foliage and of the crop is purely a radiation phenomena, brought on by the inversion, in which the soil, foilage and fruit all radiate heat to space. The result is that the atmosphere cools from the ground upward. As a result, it is not uncommon to find temperature differentials of 10 or more between the ground and 60 foot levels above the ground.
The existance of this warm air mass at higher elevations represents a very large potential energy source which can be used to oEfset a grove's net radiation heat loss.
TherP have been many m~thods and apparatus proposed in an effort to solve this freeze problem. Perhaps, the best known and most time honored is the use of "smudge pots" scattered throughout the area to be protected. While these are somewhat effect ve, they fall far short of belng the real answer to the problem. It has also been proposed to use wind machines to create a sur~ace wind simulating that which, when it naturally occurs, reduces the freeze damage. Such machines are illustrated in Towt U.S. patent 2,481,702; Potter U.S. patent
2,836,932; Beckett U.S. patent 2,895,259; Grabowski U.S~ patent
3,180,570; Coles U.S. patent 3,288,353; and Vertrees et al. U.~.
patent 3,306,533. The difficulty with such machines is that they were useful only on very calm nights and were at best very inefficient because they simply mixed the cold air next to the ground with somewhat warmer air at a limited height above the ground so that the effective raising of the temperature of the operative air mass at plant level was very low. In order to overcome this problem some attempts were made to draw air down from a higher level through a vertical duct and distribute it horizontally along the ground as in Graham U.S. patent 2,807,120. Unfortunately, such machines were not strong enough or effective enough to accomplish the result sought. Another approach is that shown in Davies U.S. patent 3,003,282 which attempted to combine the approach of drawing higher level air down through a duct with the smudge pot approach by heating it at ground level and then blowing it horizontally across the surface. Such an approach is expensive and difficult to use.
The present invention is based upon the concept of transporting large volumes of air from the higher warm air levels down to the grove floor and spreading i~ radially outwardly under the tree or foliage canopies. ThiS air spreads out radially and, being warmer air and therefore less dense, tends to ascend through and between the ~rees, transferring its heat to the fruit and ~oliage. This is a totally new concept in dealing with the freeze problem.
I provide an apparatus and method for protecting crops, particularly tree crops, against ~reezing which provides a rotor having a hub and at least two blades, each of an air-foil section, a blade retaining plate or plates connecting said blades and hub, said blade or retaining pla~es being bent upward lZ'~
to form a rotor coning angle to satisEy the rotor's aerodynamic requirements, a vertical tower fixed to the earth to inhibit gyration, a vertical drive shaft journaled in the tower, connecting means between said rotor and drive shaft at the top of the tower, drive means drivingly connected to the drive shaft at the bottom of the tower, said tower extending substantially above the level of trees to be protected, a distance sufficient to piclc up air in the inversion layer and deliver it to the ground in a generally cylindrical mass until it reaches the ground and moves radially along the ground but not so close as to disturb the soil surface and create dust. This distance is generally less than two rotor diameters and preferably one rotor diameter or less above ground level. Preferably, the rotor blades are made with a standard N.A.C.A. airfoil section.
Preferably, the warm air from approximately one rotor diameter above the rotor is drawn downwardly through said rotor at a level one rotor diameter or less above the ground level in a ~; substantially steady sta~e flow having a large number of retrograde vortices, spreads out radially along the ground level and then rising by convention and fluid friction vertically from ground level.
:~
In the foregoing general description of -the invention, I have set out certain objects,~purposes and advantages. Other~
; objects, purposes and advantages of the invention will be apparent rom a consideration of the followiny description and the acccmpanying drawings in which:
Figure 1 is a side elevational view of an apparatus according to this invention installed in an orchard grove;
Figure 2 is a top plan view of a blade retaining plate of Figure l;
, 3.
;
; ~
f.~2~fæ
Figure 3 is a section on the line III-III of the retaining plate of Figure 2; and Figure 4 is a fragmentary section of the tower and gear box of Figure 1.
Referring to the drawings, I have illustrated a tower 10 mounted on a gear box 11 fixed to a concrete pad 12 in a orchard. A vertical drive shaft 13 extends upwardly through the tower and is journaled at the top of the tower in bearings 14 and at the bottom of the tower in bearings 15. Blade retaining plates 16 are fixed to a carrier ring 17 on the top end of drive shaft 13. The blade retaining plates have a generally flat central portion 18a and blade carriers 18 extending therefrom ; with positive dihedral which carry airfoil blades 19. The lower end of the drive shaft 13 carries a bevel drive gear 20 which engages a bevel gear 21 at right angles thereto. Gear 21 i5 mounted on one end of a horizontal power shaft 22 which shaft extends out of housing 11 through bearings 23, 24. The other end of shaft 22 is connected to a drive means 25,~ such as an engine directly connected to the gear box or a tractor power take off, through a drive shaft 26 and V joint 27.
This air is carried downwar~ly and swept along the surface of the ground radially beneath the trees as shown in Figure 1. Such an apparatus when combined with the waste hea~t from the drive engine has a capacity for providing a reasonable ~; degree of frost protection over a wide area with temperature differentials.
In the foregoing specification, I have set out certain ~; preerred practices and embodiments of this învention, however t it will be understood that this invention may be otherwise embodied within the scope o the followins claims.
patent 3,306,533. The difficulty with such machines is that they were useful only on very calm nights and were at best very inefficient because they simply mixed the cold air next to the ground with somewhat warmer air at a limited height above the ground so that the effective raising of the temperature of the operative air mass at plant level was very low. In order to overcome this problem some attempts were made to draw air down from a higher level through a vertical duct and distribute it horizontally along the ground as in Graham U.S. patent 2,807,120. Unfortunately, such machines were not strong enough or effective enough to accomplish the result sought. Another approach is that shown in Davies U.S. patent 3,003,282 which attempted to combine the approach of drawing higher level air down through a duct with the smudge pot approach by heating it at ground level and then blowing it horizontally across the surface. Such an approach is expensive and difficult to use.
The present invention is based upon the concept of transporting large volumes of air from the higher warm air levels down to the grove floor and spreading i~ radially outwardly under the tree or foliage canopies. ThiS air spreads out radially and, being warmer air and therefore less dense, tends to ascend through and between the ~rees, transferring its heat to the fruit and ~oliage. This is a totally new concept in dealing with the freeze problem.
I provide an apparatus and method for protecting crops, particularly tree crops, against ~reezing which provides a rotor having a hub and at least two blades, each of an air-foil section, a blade retaining plate or plates connecting said blades and hub, said blade or retaining pla~es being bent upward lZ'~
to form a rotor coning angle to satisEy the rotor's aerodynamic requirements, a vertical tower fixed to the earth to inhibit gyration, a vertical drive shaft journaled in the tower, connecting means between said rotor and drive shaft at the top of the tower, drive means drivingly connected to the drive shaft at the bottom of the tower, said tower extending substantially above the level of trees to be protected, a distance sufficient to piclc up air in the inversion layer and deliver it to the ground in a generally cylindrical mass until it reaches the ground and moves radially along the ground but not so close as to disturb the soil surface and create dust. This distance is generally less than two rotor diameters and preferably one rotor diameter or less above ground level. Preferably, the rotor blades are made with a standard N.A.C.A. airfoil section.
Preferably, the warm air from approximately one rotor diameter above the rotor is drawn downwardly through said rotor at a level one rotor diameter or less above the ground level in a ~; substantially steady sta~e flow having a large number of retrograde vortices, spreads out radially along the ground level and then rising by convention and fluid friction vertically from ground level.
:~
In the foregoing general description of -the invention, I have set out certain objects,~purposes and advantages. Other~
; objects, purposes and advantages of the invention will be apparent rom a consideration of the followiny description and the acccmpanying drawings in which:
Figure 1 is a side elevational view of an apparatus according to this invention installed in an orchard grove;
Figure 2 is a top plan view of a blade retaining plate of Figure l;
, 3.
;
; ~
f.~2~fæ
Figure 3 is a section on the line III-III of the retaining plate of Figure 2; and Figure 4 is a fragmentary section of the tower and gear box of Figure 1.
Referring to the drawings, I have illustrated a tower 10 mounted on a gear box 11 fixed to a concrete pad 12 in a orchard. A vertical drive shaft 13 extends upwardly through the tower and is journaled at the top of the tower in bearings 14 and at the bottom of the tower in bearings 15. Blade retaining plates 16 are fixed to a carrier ring 17 on the top end of drive shaft 13. The blade retaining plates have a generally flat central portion 18a and blade carriers 18 extending therefrom ; with positive dihedral which carry airfoil blades 19. The lower end of the drive shaft 13 carries a bevel drive gear 20 which engages a bevel gear 21 at right angles thereto. Gear 21 i5 mounted on one end of a horizontal power shaft 22 which shaft extends out of housing 11 through bearings 23, 24. The other end of shaft 22 is connected to a drive means 25,~ such as an engine directly connected to the gear box or a tractor power take off, through a drive shaft 26 and V joint 27.
This air is carried downwar~ly and swept along the surface of the ground radially beneath the trees as shown in Figure 1. Such an apparatus when combined with the waste hea~t from the drive engine has a capacity for providing a reasonable ~; degree of frost protection over a wide area with temperature differentials.
In the foregoing specification, I have set out certain ~; preerred practices and embodiments of this învention, however t it will be understood that this invention may be otherwise embodied within the scope o the followins claims.
4.
Claims (7)
1. An apparatus for protecting crops, particularly tree or orchard crops, from frost damage comprising a vertical tower fixed to earth against gyration, a vertical shaft extending lengthwise through said tower, a rotor on the top end of said shaft above the tower, said rotor including a blade retaining member bent upward to form a conical angle, at least two blades of airfoil section, means connecting said blades to said blade retaining member at a pitch angle satisfying the rotors aerodynamic requirements and drive means drivingly connected to the drive shaft at the bottom of the tower, said tower projecting substantially above the level of the trees of the crop to be protected at a height sufficient for the rotor to pick up air in the inversion layer and deliver it to the ground to spread out radially along the earth generally beneath the foliage of the tree crop and then upwardly through and between the tree foliage and wherein the rotor blades are spaced above the ground a distance sufficient to pick up air in the inversion layer but within the ground effect of zone of the rotor.
2. An apparatus as claimed in claim 1 wherein the blades are made with a standard N.A.C.A. airfoil section.
3. An apparatus as claimed in claim 1 or 2 wherein the vertical shaft is driven by a horizontal shaft through a pair of bevel gears.
4. An apparatus as claimed in claim 3 wherein the horizontal shaft is driven by a power take off from a tractor.
5. An apparatus as claimed in claim 1 or 2 wherein the tower projects one rotor diameter or less above the ground.
6. An apparatus as claimed in claim 3 wherein the tower projects one rotor diameter or less above the ground.
7. An apparatus as claimed in claim 4 wherein the tower projects one rotor diameter or less above the ground.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US52373783A | 1983-08-16 | 1983-08-16 | |
| US523,737 | 1983-08-16 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1244242A true CA1244242A (en) | 1988-11-08 |
Family
ID=24086260
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000445751A Expired CA1244242A (en) | 1983-08-16 | 1984-01-20 | Methods and apparatus for preventing or retarding fruit and vegetable freezing |
Country Status (3)
| Country | Link |
|---|---|
| BR (1) | BR8401350A (en) |
| CA (1) | CA1244242A (en) |
| MX (1) | MX160723A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111742771A (en) * | 2020-07-02 | 2020-10-09 | 商丘市农林科学院 | Wheat late frost resisting device and using method thereof |
-
1984
- 1984-01-20 CA CA000445751A patent/CA1244242A/en not_active Expired
- 1984-03-23 BR BR8401350A patent/BR8401350A/en unknown
- 1984-03-27 MX MX20079584A patent/MX160723A/en unknown
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111742771A (en) * | 2020-07-02 | 2020-10-09 | 商丘市农林科学院 | Wheat late frost resisting device and using method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| MX160723A (en) | 1990-04-25 |
| BR8401350A (en) | 1985-06-11 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |