WO2022118052A1

WO2022118052A1 - Frost protection machine

Info

Publication number: WO2022118052A1
Application number: PCT/HU2021/050014
Authority: WO
Inventors: Endre FARAGÓ
Original assignee: Farago Endre
Priority date: 2020-12-03
Filing date: 2021-02-24
Publication date: 2022-06-09
Also published as: HUP2000408A1; HU5433U

Abstract

The present invention relates to a frost protection machine (1) for preventing frost damage in open-air horticultural plantations, comprising a mobile chassis (2), provided with an air-conducting housing (4) with an air inlet (5), an air outlet (6) and a fan (7). The essence of the invention lies, in that the housing (4) is design cylindrically and arranged vertically. The air inlet (5) of the housing (4) is located at least 3.4 meters from the ground surface (14). Furthermore, the fan (7) is designed as an axial fan (7). On the chassis (2), a conical baffle (13) is arranged at an axial distance (12) from the air outlet (6) of the housing (4). The conical baffle (13) is capable of radially and evenly distribution of the treatment air flow at the air outlet (6) and mixing it with a relative colder air layer of the ground surface (14) in order to eliminate the frost risk.

Description

FROST PROTECTION MACHINE

The present invention relates to a frost protection machine which provides frost protection for plantations, in particular fruit trees, berries, vegetables and flowers, against springautumn frosts which endanger outdoor production, by means of a relatively warmer air flow treatment.

According to meteorological observations, it has not been a year without early frost in Hungary. From March to the end of May, we usually have to count 14-20 days when the air temperature drops below O °C at a height of 2 m. But, ground-based frosts can occur even in early June. The main question in assessing the extent of frost damage is the stage of development, the extent, type and duration of frost on the plants. The extent of the damage depends on these factors. For example, the most frost-sensitive parts of fruit trees are flower buds in full bloom and the fruit initiatives that have just bound within 2-3 weeks of petal death. In flowering, 50 % frost damage can be expected if the air temperature is between minus 3.3 - 6.7 °C. At the end of flowering, frost at minus 2.7 - 3.6 °C and bound fruits can also be severely damaged by frost at -1 and -2 °C.

In practice, various frost protection solutions are known. Such as, e.g. commercially known as "TOW BLOW" a fan machine, which is a fixed machine that can be installed in a plantation with a range of 50-70 m radius and a manageable area of 0.8-1.5 Ha, so a significant overlap loss is to be expected. A further disadvantage thereof is that, the machine itself and its operation are too expensive, and on the other hand, the slightest wind movement diverts the operating air flow from the area to be protected. The driving internal combustion engine is located directly in front of the fan, so the suction profile of the fan is partially obscured by the motor itself and its components, thus degrading the amount of air drawn in and out. This machine takes the required energy content from the higher air layers. As the operating mode of the machine is fixed, it cannot take into account the actual atmospheric conditions.

Another solution known in the practice as "TOG-DRAGON". The amount of energy required for protection is determined by combustion heat of straw, logs, etc. loaded into the boiler arranged on the trailer. The amount of heat thus generated, together with the smoke gen- erated during combustion, leaves the plantation upwards. The power of the air mixer fan is only approx. 1/5 -1/7 of the air transport capacity of this frost protection machine.

According to our practical experience, the decisive factor for the effectiveness of spring frost protection is that the frost protection machine must return to the protected area in at least 20-25 minutes, otherwise the temperature of the protected area will equalize with the temperature of the non-protected area. In this case, the damage (heat stress) of the treated plantations may also be significant. The above machine needs to be refuelled every 4-5 hours. Forced recooling of the heated boiler and loading of combustible materials is a serious waste of time.

Also known as "FROST-BASTER" is a towed machine that generates heat by gas combustion. The outlet air temperature is 350-400 °C. Its disadvantage is that air at this temperature, due to the difference in density, takes off from the treated plantation in just a few tenths of a second, i.e. it does not have a permanent antifreeze effect. Moreover, in the meantime, it even causes a "heat shock", e.g. in open-flowered plantations. The air delivery of the machine is low; it is only designed to blow off the amount of heat generated. Gas cylinders need to be replaced frequently, so the machine can only operate for 3-4 hours per day. It is expensive to operate and it is practically impossible to repeat the treatment within 20-25 minutes.

A similar solution is described in the EP-0845204 patent document. It has housing, a fan and a heater on a mobile chassis. At the air outlet of the housing, the hot air is forced out of the heating and blowing system so that it travels in a substantially horizontal direction and thus mixes with the colder air layer close to the ground surface. This machine is complicated, expensive to operate and does not allow the treatment to be repeated cyclically in a short time.

However, practical experience has shown that only a very small proportion of the energy content of the heated air causes a rise in temperature in the ground air layer, the vast majority leaving uselessly upwards from the plantation airspace and replaced by cold air masses from the side. This is due to the lighter specific gravity of the out flowing air at 40- 80 °C. Furthermore, the intake and heated air largely loses even its humidity when heated, thus placing the area to be protected in an even worse position than the untreated area, since drier air at the same frost values even increases frost damage, e.g. in the flowers.

It is an object of the present invention to overcome the above drawbacks, i.e. to provide an improved solution which can be used universally in horticultural plantations to effectively improve the efficiency and economy of frost protection and which - by effectively mixing its treating air stream with the air layer of the soil surface -, it can prevent, or at least substantially reduce, the frost damage in the treated plantation.

The object is achieved by an improvement of the last mentioned machine, which - according to claim 1 - has a mobile chassis, on this an air flow housing is provided, which is provided with an air inlet, an air outlet and a fan.

The essence of the present invention is that the housing has a cylindrical design and is arranged vertically on the chassis. The air intake of the air flow house is located at least 3.4 meter high from the ground surface. Furthermore, the fan is designed as an axial fan. Furthermore, a conical baffle is arranged on the chassis at an axial distance from the fan air outlet, which is able to radially spread the operating (treating) air flow of the machine.

Suitable improvements are described in the subclaims.

The invention is based on the recognition that the set task can be solved by using the "inverter" of the atmosphere as a meteorological phenomenon and applying it purposefully to the indicated task. Above the sub-freezing air layer along the ground, there are increasingly warmer air layers. By constantly aspirating the relatively warmer air layers, preferably at a height of 4-20 m above the ground surface and mixing them into the relatively colder ground air layer, the plantation can be reduced or eliminated to the naturally occurring frostbite, even without the use of any additional heating device! The specific gravity of the treatment air stream mixed directly into the lower air layer enclosing the plantation will not be significantly lower than that of the air layer directly above the plantation (since their temperature difference is preferably only 4-5 °C), so the treating air flow does not increase the temperature of the the lower air layer enclosing the plantation considerably, and by heating it slightly - it remains permanently in the area just above the plantation, and thus can have a beneficial anti-frost effect permanently. The proposed machine therefore obtains heat energy required for frost protection exclusively from warmer air layers located at 3.4 to 20 meters above the plantation. This can significantly increase the efficiency and economy of the frost protection as a whole.

According to the invention, the treatment air stream exiting the frost protection machine is impeded on the proposed conical baffle and is forced to flow radially in the orchard below the trunk height canopy. The conical baffle also protects the sensitive inflorescence below from the air flow (wind) generated by the treatment air stream. The large surface of the inflorescences does not impede the lateral propagation of the treating air flow.

It is to be noted that „the treatment air flow" raises the temperature of the ground surface air layer only slightly, preferably by 0.3-1.5 °C, once the machine has passed through the area to be protected. Therefore, this operation should be repeated cyclically several times, preferably in every 10-20 minutes. In our experiments with the proposed machine, we measured an area performance between 2-5.0 Ha. The tractor was travelling at a speed of 8-9 km/h and a grip width of 20 m.

The operation of the machine according to the invention was based on the meteorological forecast of the frost risk. But we could also base this on the locally obtained measurement results of the plantations. On such frost-prone days, it is advisable to start the defence in the plantation to be protected late afternoon (6:00-7:00 p.m.). Then the heat energy obtained from the upper air layers can be communicated to the plantation, which has not even reached below freezing point, with which the cooling can be reduced in advance.

Using the present invention, the burden on the environment and the cost of frost protection has been minimized.

The invention will now be described in more detail with reference to the accompanying drawings, in which an exemplary embodiment of a frost protection machine according to the invention is shown. In the drawings:

• Figure 1 is a schematic side view of a machine according to the invention in a coupled state to a tractor;

• Figure 2 is a side view of the machine of Figure I on a relatively larger scale; • Figure 3 is a perspective view of the solution of Figure 2 with "an X-ray image" of the housing;

• Figure 4 is a vertical section of the machine according to Figs. 2-3.

As shown in Figures 1-4, the frost protection machine 1 according to the invention has a mobile chassis 2 which is connected to a tractor T in a known manner by a drawbar 3. The mobile chassis 2 is in this case designed as a single-axle trailer. On the chassis 2 there is a cylindrical air-conducting housing 4 arranged vertically, the diameter of which is denoted by D and the height by M (Fig. 4). At the upper end of the housing 4, in this case at a height of 3.4 m, it has air inlet 5, and at least one air outlet 6 at its lower end (Fig. 2). (The height of the housing 4 is limited by the traction requirement of the machine 1 between fruit trees.) In the present case, the diameter D of the housing 4 was chosen to be 1150 mm and the height M was chosen to be 2250 mm. The center line of the cylindrical air suction housing 4 is indicated by reference numeral Kjn Figure 3.

In the present case, at the lower end of the housing 4, e.g. within the air outlet 6 an axial fan 7 is arranged coaxially, a rotatable mounted impeller 8 of which is connected to the torque-transmitting stub shaft (not shown) of the towing tractor T via a shaft S, an accelerator gear 10, an impeller shaft 9 and a cardan shaft 11 in a known manner (see Figs. 1 and 4). Its normal operating speed of the shaft S is 540 rpm, which is increased by the accelerator gear 10 to 2'200 rpm, so that in the present case the axial fan 7 has an air delivery capacity of 77500 m³/h, where the freewheel impeller 8 has a diameter of 1050 mm.

The axial fan 7 is thus able to exert a huge downward suction force on the inner area of the housing 4 on upper air layers above 3.4 m. As a result of the suction effect of the driven axial fan 7, it draws air from the upper air layer higher than 3.5 m through the cylindrical shell of the housing 4, preferably with an air transport capacity of between 30000 and 150000 m³/h.

It can be seen in more detail in Fig. 4, that under the axial fan 7 a coaxially conical baffle 13 is arranged at an axial distance 12, the size of which has been chosen to be 220 mm. The primary function of the conical baffle 13 is to radially evenly distribute the highly turbulent air treatment flow forced from the air inlet 5 to the air outlet 6 (indicated by curved arrows in Figure 4) and to effectively mix it with the relatively cold air layer of the above-ground surface 14, thereby to eliminate the freezing (frost) risk of the plantation.

In the present embodiment, the distance of the lower edge of the housing 4 from the ground surface 14 was chosen to be 1150 mm. The conical baffle 13 also serves to protect the underlying plants from strong air streams. The housing 4, at its upper end, is equipped with protective grill 16 to prevent an ingress of plant parts or birds.

The operation of the frost protection machine 1 according to the invention is, as follows:

The machine 1 towed by the tractor T in the direction of the arrow 15 is thus mobile, capable of continuous operation for at least 12 hours and designed during operation, e.g. moves in a "rotating shift" in the target area (plantation) to be protected. It travels continuously in the plantation to be protected from frost, while the turbulent treatment air flow (extracted from the height) is directed downwards and then radially spread evenly over a radius of 18-40 meters. Thereby the treatment air flow is forced into the lower layer of air enclosing the plantation, thereby heating it slightly e.g. by 0.3-1.5 °C per pass, which is sufficient - according to our tests - to eliminate the risk of frost.

As an example, before start of the treatment, the temperature T1 of the air layer at the soil surface 14 was -3 °C and the temperature T2 of the aspirated air layer above 3.4 m was + 2 °C (see Fig. 4).

It is advisable to start the frost protection operation before the onset of frost, preferably in the early evening hours (between 6 pm and 8 pm) and after the frost danger, to continue in the next morning (preferably between 7 am and 9 am). The size of the protected area depends on real-time (current) environmental factors, the available technical power (parameters of the T tractor and the 7 axial fan) and the characteristics of the protected vegetation. Taking these into account, the recommended machine 1 per shift can be used successfully for the frost protection on 0.5-8.0 Ha surfaces. The traction / forward speed of machine 1 was chosen to be between 1.0 - 9.8 km/h in our experiments. The traction direction is indicated in Figures 1-3 by an arrow 15.

Thus, unlike the known methods, the solution according to the invention not only mixes a relatively warmer treatment air stream extracted from above air layers with a relatively colder air stream directly at the ground surface 14, but - in an original manner - practically artificially and purposefully creates a "low thermal inversion air layer" above the ground surface 14, at the height of the crop zone. In our experimental results, this is a significant technical-agronomic additional effect of the machine 1 according to the invention, the pregnant advantages of which have already been mentioned above.

Finally, it is mentioned that in addition to the illustrated exemplary embodiment, several other embodiments of the machine 1 according to the invention are possible within the claimed scope. For example, the mobile chassis 2 can be mounted on a tractor or implement or on a trailer. Furthermore, in order to increase the turbulence of the air flow in the cylindrical housing 4, one or more additional vortex generating element, e.g. spiral spine plate can be used.

In order to increase the temperature of the treatment air flow, the outer circumferential surface of the housing 4 can optionally be provided with a heating coil and /or a perforated coil (not shown) can be provided on the inner circumferential surface of the housing 4, which can be connected e.g. to the tractor T exhaust pipe (not illustrated) with a flexible heat-resistant hose. In this way, the residual heat content of the exhaust gases can be utilized to increase the temperature of the treating air stream.

Optionally, the housing 4 can be provided with a unit for dispensing water into the treatment air stream. Such an embodiment is also possible (not shown) in which the relative angular position of blades of the impeller 8 of the axial fan 7 can be adjusted relative to the horizontal. This makes it easy to control the air delivery power of the axial fan 7.

LIST OF REFERENCE CHARACTERS USED:

1 - Frost protecting machine;

2 - Mobile chassis;

3 - Drawbar;

4 - Air-conducting housing;

5 - Air intake;

6 - Air outlet;

7 - Axial fan;

8 - Impeller;

9 - Axis;

10 -Gear;

11 - Cardan shaft;

12 - Axial spacing;

13 - Conical baffle;

14 - Soil surface;

15 - Arrow (traction direction);

16 - Protective grill;

D - Diameter of the housing;

K - Center line of the housing;

M - Height of the housing;

DI - the diameter of the impeller;

S - Shaft;

T - Tractor;

T1 - temperature of the air layer closest to the soil surface, before treatment;

T2 - temperature of the air layer at least 3.4 m high (from the soil surface).

Claims

9

CLAIMS: A frost protection machine, in particular for preventing frost damage in open-air horticultural plantations, having a mobile chassis, provided with an air-conducting housing, which is provided with an air inlet, an air outlet and a fan, characterized in that the housing (4) is design cylindrically and arranged vertically, the air inlet (5) of the housing (4) is located at least 3.4 meters from the ground surface (14), and the fan (7) is designed as an axial fan (7), and on the chassis (2) a conical baffle (13) is arranged at an axial distance (12) from the air outlet (6) of the housing (4), said conical baffle (13) is capable of radially and evenly distribution of the treatment air flow and mixing thereof with a relative colder air layer of the ground surface 14. The frost protection machine according to Claim 1, characterized in that the axial fan (7) is arranged in a region of the air outlet (6) of the housing (4). The frost protection machine according to Claim 1 or 2, characterized in that a shaft (9) of an impeller (8) of the axial fan (7) is in drive connection with a torque-transmitting shaft stub of the tractor (T) for towing and/or hitching the mobile chassis (2). The frost protection machine according to any of Claims 1 to 3, characterized in that the axial fan (7) has an air transport capacity of at least 30000 m³/h. The frost protection machine according to any of Claims 1 to 4, characterized in that the conical baffle (13) and the axial fan (7) are arranged coaxially with the cylindrical housing (4).