GB2133664A - Apparatus and method for imparting motion to growing plants - Google Patents

Abstract

Apparatus for imparting motion to a part of a growing plant includes means (10) for providing a pressurized stream of air, such as a compressed air source, feeding into a pressurized chamber (12) which has an outlet (14) provided with a flow modulating valve (16) arranged to provide a pulsed stream of air. An outlet nozzle (18) is arranged to direct the air stream at the part of the plant to be vibrated. The frequency of the pulses exceeds 200 c.p.m. and the apparatus can be used for pollinating plants, for harvesting fruit from plants, or measuring the natural frequency of a plant portion. <IMAGE>

Description

SPECIFICATION Apparatus and method for imparting motion to growing plants The present invention relates to apparatus and a method for imparting motion to growing plants, and more particularly to such apparatus and method when used for plant husbandry and harvesting.

The use of vibration in agricultural applications is well known. One example of the use of vibration in harvesting is the engagement of a vibratory shaker mechanism to the trunk of a tree for vibrating the entire tree at a frequency which causes the fruit thereof to disengage therefrom.

The use of an oscillating air stream for fruit harvesting is proposed in a paper entitled, "Pneumatic Tree-Fruit Harvesting Utilizing a Pulsating Air Stream" by O.M. Abu-Gheida, B.A. Stout and S.K.

Ries, presented as Paper 61 -600B at the Winter Meeting of the American Society of Agricultural Engineers at Chicago, Illinois, December 1961. In this paper, it was proposed to direct a relatively low frequency air stream, whose variation over time approximated a cosine curve, upwardly into the branches of trees for separating fruit from the trees and for slowing the descent of the fruit to reduce bruising thereof. The test apparatus included a fan having an air inlet which was periodically closed.

Thus, a relatively smooth oscillatory air flow was produced. Oscillation rates up of to 180 cycles per minute were investigated.

A paper entitled "Harvesting Citrus Fruit with an Oscillating Air Blast" presented in June 1962 as Paper 62-155 at the Annual Meeting of the American Society of Agricultural Engineers describes a harvesting technique employing oscillating vanes which modulate a high volume air stream.

It has been found by the applicant that the prior art proposals to use an oscillating stream of air suffer from number of disadvantages which render them less than satisfactory in operation, as acknowledged in the above-mentioned publications. The major disadvantage is that the frequencies employed are far lower than the natural frequencies of the plant portions sought to be vibrated and thus efficient fruit separation is not realized. Secondly, leaves and other portions of the tree which have lower natural frequencies tend to be damaged by the prior art techniques. The apparatus employed in the prior art proposals is by its construction limited to oscillation frequencies below 200 c.p.m. since attempted operation at higher frequencies produces a continuous air stream.Thus, the use of the apparatus and techniques proposed in the prior art has not met with commercial acceptance for fruit harvesting.

Vibration has a number of other potential agricultural applications. One of these is inducing pollination in tomato blossoms in a greenhouse or under other conditions where spontaneous pollination does not occur. Conventionally, the forced vibration has been accomplished by hand or with an electrically operated hand-held vibrating probe or other tool.

In an article entitled "Acoustically Forced Vibration of Greenhouse Tomato Blossoms to Induce Pollination", Transactions of the ASAE, 1968, it is proposed to employ high frequency acoustic energy for vibrating the bloom. A significant disadvantage of the proposed technique is the extremely high sound level required, in the range of 150db. This technique is not in commercial use.

The present invention seeks to overcome disadvantages of the prior art apparatus and techniques for vibrating growing plants and to provide vibrating apparatus and techniques for enabling vibration of specific parts of growing plants so that desired results in a wide range of applications can be achieved.

The present invention accordingly provides apparatus for imparting vibration to a plant or parts thereof comprising; means for providing a pressurized stream of air; means for periodically interrupting said stream of air so as to provide pulses of pressurized air; and means for applying said periodically interrupted stream of pressurized air into driving engagement with a plant, wherein the frequency of the pulses of pressurized air exceeds 200 pulses per minute.

Further, in accordance with an embodiment of the invention, the frequency of the pulses of pressurized air is arranged to be in the vicinity of the natural frequency of the plant portion to be vibrated.

Additionally, in accordance with one embodiment of the present invention, the means for periodically interrupting the stream of air comprises an apertured rotating disc. Alternatively, any suitable air flow valve operating at the desired frequency may be employed.

Such apparatus may be used to measure the natural frequency of a portion of a plant, when combined with apparatus for varying the frequency of the pulses and display apparatus indicating the frequency of the pulses being imparted at a given time.

Such apparatus may also be used for induction of self-pollination of plants. Preferably this apparatus operates at a frequency in the range of 800-1800 pulses per minute, and particularly between 13001800 pulses per minute for tomato plants.

The present invention further provides a method of pollinating plants comprising the steps of: providing a pulsed stream of pressurized air; and directing said pulsed stream of pressurized air at the pollen containing portions of the plants.

The present invention still further provides a method of harvesting fruit from plants comprising the steps of: providing a pulsed stream of pressurized air; and directing said pulsed stream of pressurized air at the fruit of the plants to dislodge the fruit therefrnni In accordance with embodiments of the present invention, efficient vibration of a portion of a plant is provided by means of a pulsed stream of air directed at the plant. It is particularly advantageous that the frequency of the pulsed stream of air is arranged to be at or near the natural frequency of the plant or the part of the plant sought to be vibrated. This is particularly effective at dislodging fruit or pollen from the plant with a minimum requirement of input energy as the natural frequency of the plant portion is utilized to enhance the induced vibration.In contrast, the prior art proposals for using oscillating streams of air for vibration of plants or parts thereof did not operate at or near the natural frequency of the portions of the plant sought to be vibrated and for this reason, interalia, the previously proposed techniques have not had commercial success.

The present invention will be more fuliy understood and appreciated from the following detailed description of embodiments thereof, given by way of example, and when taken in conjunction with the accompanying drawings, in which: Figure I is a schematic illustration of vibration producing apparatus constructed and operative in accordance with an embodiment of the present invention; Figure2A is a schematic illustration of natural frequency measuring apparatus constructed and operative in accordance with an embodiment of the present invention; Figure 2B is a detail illustration of the valve mechanism of the apparatus of Figure 2A; and Figure 3 is a schematic illustration of pollination and harvesting apparatus constructed and operative in accordance with another embodiment of the present invention.

Referring to Figure 1, there is shown, in schematic form, vibration producing apparatus constructed and operative in accordance with an embodiment of the present invention and which comprises a source of pressurized air 10, such as a canister of highly compressed air, an accumulator associated with an air compressor, or the output of a fan or other low pressure air generator. The pressure at the source of pressurized air 10may vary from approximately 160Kg/m2 to 20,000Kg/m2. The source of pressurized air is coupled to a pressurized air chamber 12 which defines an outlet 14. An outlet 14, there is provided a pressurized air flow modulating valve 16 terminating in an outlet nozzle 18.Valve 16 may be of conventional construction and may be any airflow valve suitable for periodically interrupting the stream of air so as to provide pulses of pressurized air and which can be operated at the desired frequency.

It may be readily appreciated by persons skilled in the art that the apparatus of Figure 1 may be used to measure the natural frequency of a portion of a plant. Figure 2A is a schematic illustration of an embodiment of the present invention designed and operative to measure the natural frequency of parts of plants. Like elements in Figures 1 and 2A have like references numerals. Figure 2B is a detail illustration of the valve mechanism 16 of Figure 2A.

As seen in Figure 2A, vibration producing appar atus similar two that illustrated in Figure 1 is provided which comprises a source of pressurized air 10 coupled to a pressurized air chamber 12 which defines an outlet 14. At outlet 14 there is provided a pressurized airflow modulating valve 16 terminating in an outlet nozzle 18. One such valve 16, particularly suited for frequency measuring purposes, is illustrated in Figure 2B and comprises a high speed rotary disc 20 having one or more openings 22 formed therein to permit air outflow through outlet 14 during the time when an opening is aligned with the outlet. Rotary disc 20 may be powered by a variable speed electric motor 24 which permits adjustment of the frequency of air pulses exiting from the outlet 14.

This vibration producing apparatus is combined with a vibration frequency display 30 which is coupled to a tachometer sensor 32 located at the drive shaft of the rotating apertured disc 20. A variable speed drive control such as a potentiometer 34 may be employed to vary the periodicity of vibration produced bythevibration producing apparatus until the plant portion is observed visually or by other sensing means to vibrate in resonance.

Such frequency, indicated by display 30, is determined to be the natural frequency of the plant portion.

Reference is now made to Figure 3 which illustrates pollination and harvesting apparatus constructed and operative in accordance with an embodiment of the present invention, and comprising a power source, such as a dry cell battery 40 which is electrically coupled to an electric motor 42. Alternatively, the power source may comprise a source of compressed air which is coupled to an airturbine.

The electric motor 42 or air turbine drives an apertured cylinder 44 which is located at an outlet 47 of a compressed air reservoir 46. Compressed air reservoir 46 is coupled to a source of compressed air 50 which may be coupled externally of the apparatus by means of an air hose 48. Alternatively, electric motor 42 may also drive an air compressor which may be located within the apparatus for providing compressed air to reservoir 46.

According to a preferred embodiment of the invention, apertured cylinder 44 is driven at a speed so as to produce an output periodicity of approximately up to 3000 cycles per minute. The pulsed air provided at outlet 47 is passed through a nozzle 52 for being directed at plants for encouraging pollination thereof by means of dislodging the pollen from the stamens thereof and distributing it within the flower such that the pollen settles upon the flower stigma.

The apparatus of Figure 3 may be used both in greenhouses and in the field. The electric motor driven version is ideal for use in the laboratory or small greenhouse. For pollination of open fields of tomatoes, however, it is preferred to utilize a large compresser in conjunction with a blower which provides a greater amount of air and thus sends the pulses of air over a much broader area. Such an embodiment of the invention may be mounted upon an agricultural tractor for movement among the plants.

The apparatus of Figure 3 operates as harvesting apparatus by directing pulses of compressed air at the desired frequency towards the fruit to be harvested. The apparatus causes the fruit or the branches upon which it rests to resonate at or about their natural frequency, and the fruit is thereby dislodged.

It will be appreciated by those skilled in the art that the invention is not limited to what has been particularly shown and decribed hereinabove.

Rather, the scope of the present invention is defined only by the claims which follow.

Claims (17)

1. Apparatus for imparting vibration to a plant or parts thereof comprising: means for providing a pressurized stream of air; means for periodically interrupting said stream of air so as to provide pulses of pressurized air; and means for applying said periodically interrupted stream of pressurized air into driving engagement with a plant, wherein the frequency of the pulses of pressurized air exceeds 200 pulses per minute.

2. Apparatus according to claim 1, wherein the frequency of the pulses of pressurized air is arranged to be in the vicinity of the natural frequency of vibration of the plant portion to be vibrated.

3. Apparatus according to claim 1 or claim 2, wherein said means for periodically interrupting comprises an apertured disc which is rotated in periodically blocking relationship with said pressu rized stream of air.

4. Apparatus according to claim 1 or claim 2, wherein said means for periodically interrupting comprises an apertured cylinder which is rotated in periodically blocking relationship with said pressu rized stream of air.

5. Apparatus according to any one of the preced ing claims, wherein said stream of pressurized air is at positive pressure.

6. Apparatus for measuring the natural frequen cyofa portion of a plant, comprising: apparatus for imparting vibration to a plant according to any one of claims 1 to 5; means for selectably varying the frequency of said pulses; and display means for indicating the frequency of said pulses at a given time.

7. Apparatus for pollinating plants, comprising: apparatus for imparting vibration according to any one of claims 1 to 5; and nozzle means for imparting said periodically interrupted stream of pressurized air into driving engagement with the flower of a plant for dispersal of pollen grains contained therein and depositing them on the stigma thereof.

8. Pollinating apparatus according to claim 7, wherein the frequency of said pulses is approximately 800 to 1800 c.p.m.

9. Pollinating apparatus according to claim 8, wherein the frequency of said pulses is between 1300 and 1800 c.p.m.

10. Apparatus for harvesting fruit from plants, comprising: apparatus for imparting vibration according to any one of claims 1 to 5; and nozzle means for imparting said periodically interrupted stream of pressurized air into driving engagemenu with the fruit of the plant for the dislodging thereof from the plant.

11. A method of pollinating plants comprising the steps of: providing a pulsed stream of pressurized air; and directing said pulsed stream of pressurized air at the pollen-containing portions of the plants.

12. A method according to claim 11, wherein the frequency of the pulses of pressurized air exceeds 200 pulses per minute.

13. A method accordng to claim 12, wherein said pulsed stream comprises a stream having a pulsation frequency of 800 to 1800 c.p.m.

14. A method of harvesting fruit from plants comprisng the steps of: providing a pulsed stream of pressurised air; and directing said pulsed stream of pressurized air at the fruit of the plants to dislodge the fruit therefrom.

15. A method according to claim 14, wherein the frequency of the pulses of pressurized air exceeds 200 pulses per minute.

16. Apparatus substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

17. A method of pollinating plants or a method of harvesting fruit from plants, substantially as hereinbefore described with reference to the accompanying drawings.