WO1999025482A1

WO1999025482A1 - Variable flow control device for precision application

Info

Publication number: WO1999025482A1
Application number: PCT/US1998/022109
Authority: WO
Inventors: Alvin R. Womac; Quy Duc Bui
Original assignee: The University Of Tennessee Research Corporation
Priority date: 1997-11-18
Filing date: 1998-10-20
Publication date: 1999-05-27
Also published as: AR014030A1; CA2310464A1; AU741348B2; EP1030738A1; US5908161A; AU1102999A

Abstract

The present invention relates to an apparatus for variable flow control for precision applications, such as agro-chemical applications. The invention is directed towards a flow control device comprising a metering rod (22) movably mounted within a housing (10). The position of the metering rod (22) is controllable so as to control the flow rate, flow angle, and/or droplet size of fluid passing through the flow control device of the present invention.

Description

TITLE: VARIABLE FLOW CONTROL DEVICE FOR PRECISION APPLICATION

BACKGROUND OF THE INVENTION

1. Field of The Invention

The present invention relates to an apparatus for variable flow control for

precision applications, such as agrochemical applications. The invention is directed towards a flow control device comprising a metering rod moveably mounted within

a housing. The position of the metering rod is controllable so as to control the flow

rate, flow angle and/or droplet size of fluid passing through the flow control device

of the present invention. 2. Description of the Prior Art

The ability to vary the application rate of agrochemicals is highly desirable

in the field of precision farming. Variable rate applications of chemicals are

desirable to respond to changes in soil and/or crop and/or pest conditions.

There are at least three prior art methods for variable rate agrochemical

applications. The first method varies the nozzle pressure to alter the spray rate.

This method is unsatisfactory because pressure must be increased by a factor of

four in order to double the spray rate. Pressure increases of this magnitude

decrease the droplet size and result in difficulties maintaining a selected spray

pattern at low pressures. A second prior art method of variable rate application is to equip an

applicator with several application systems having different capacities. Such

systems can be turned on or off in response to changes in crop and/or soil and/or

pest conditions. This method is unsatisfactory because it is electromechanically

complex and it provides only stepwise variations, rather than continuous variations,

in flow rate. Stepwise variations limit the suitability of such devices for crop and/or

soil and/or pest conditions that require only slight variations in application flow rates.

A third prior art method for achieving variable rate agrochemical application

is the use variable rate flow control nozzles on a spray system, such as a boom

sprayer. Prior art devices employing this method have incorporated pulsed

solenoids into a nozzle body to control application rate and drop size. In a typical

boom spray system, nozzles are spaced out approximately every 20 inches. In such a system, a pulsed solenoid flow control apparatus is electrically complex and

subject to harsh boom conditions, and more importantly is limited in range of flow

rate since the solenoid is only in series with a nozzle orifice.

The present invention provides a true variable rate flow control device which

is robust and which is capable of controlling flow rate, droplet size, and/or spray

angle through the use of a control pressure or other rod driving means.

SUMMARY OF THE INVENTION

The variable flow control device of the present invention comprises a housing

having a top, a bottom, at least two opposite sides, and a central longitudinal channel having an upper region and a lower region. A metering rod is moveably

mounted in the central longitudinal channel. The metering rod has an upper portion

and lower portion. A metering rod driver is coupled to the upper portion of the

metering rod such that downward movement of the driver results in downward

movement of the metering rod and upward movement of the driver results in

upward movement of the metering rod.

A supply pressure port is located in a side of the housing. A spray head is

attached to the lower portion of the metering rod and is mounted in the lower portion

of the longitudinal channel. The spray head has an upper end and a lower end. An

expandable spray channel is centrally located in the spray head. A supply pressure volume extends from the supply pressure port to the spray channel.

DESCRIPTION OF THE DRAWINGS Figure 1 is a side cross sectional view of a first embodiment of the present

invention with the metering rod in an extended position.

Figure 2 is a side cross sectional view of a second embodiment of the

present invention with the metering rod in an extended position.

Figure 3 is a side view of a second embodiment of the metering rod driver,

metering rod, spray head and spray nozzle assembly of the present invention with

the spray channel in the open position.

Figure 4 is a side view of a first embodiment of the metering rod and spray

head with the spray channel in the closed position. Figure 5 is a side view of a third embodiment of the present invention. Figure 6 is a bottom view of the spray head of Figure 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention comprises a housing 10 having a top 7, a bottom 8, and at

least two opposite sides 9, and central longitudinal channel 6, having an upper

region 5 and a lower region 4, as shown in Figures 1 and 2. The housing may

consist of a one piece structure or it may comprise several parts which are attached to each other such as by threaded fittings, welding, adhesive or pressfit.

In one preferred embodiment, as show in Figure 1 , the lower region of the

longitudinal channel decreases in cross sectional area as a function of distance

away from the bottom of the housing. In another preferred embodiment, as shown

in Figure 2, the lower region of the longitudinal channel increases in cross sectional

area as a functional distance away from the bottom of the housing. The

embodiment shown in Figure 2 is capable of atomizing fluid ejected from the bottom

of the housing.

The invention further comprises a metering rod 22 moveably mounted in the

central longitudinal channel, as shown in Figures 1 and 2. The metering rod has

an upper portion 21 and lower portion 23. A metering rod driver 24 is coupled to the

upper portion of the metering rod such that downward movement of the driver

results in downward movement of the metering rod and upward movement of the

driver results in upward movement of the metering rod. In a preferred embodiment as shown in Figure 3, the driver comprises a mechanical linkage 11 having a first end 13 coupled to the upper portion of the

metering rod and a second end 15 opposite the first end. The driver further comprises a step motor 17 coupled to the second end of the mechanical linkage.

In the preferred embodiments depicted in Figures 1 and 2, the coupling of the

metering rod driver to the metering rod is a fluid coupling.

The invention further comprises a supply pressure port 18 located in a side

of the housing, as shown in Figures 1 and 2. A spray head 26 is attached to the

lower portion of the metering rod and mounted in the lower portion of the

longitudinal channel. The spray head has an upper end 25 and a lower end 27, as

shown in Figures 1 and 2. An expandable spray channel 28 is centrally located in

the spray head, as shown in Figures 1-4. In a preferred embodiment, the

expandable channel extends across the spray head, as shown in Figure 6.

In a preferred embodiment the spray head is sized such that the expandable

spray channel is open, as shown in Figure 1 , when the spray head extends to the

bottom of the housing, and the expandable spray channel is closed, as shown in

Figure 4, when the spray head is in a retracted position within the longitudinal

channel. The closure of the expandable channel results from interference between

the lower end of the spray head and the tapered longitudinal channel. In a

preferred embodiment, the lower end of the spray head is tapered at a substantially similar angle to the angle of the lower region of the longitudinal channel. The spray head and housing configuration depicted in Figure 2 is capable of atomizing fluid ejected from the bottom of the housing. The embodiment of the

invention depicted in Figure 2 is also capable of being operated so as to

independently control the droplet size and flow rate of fluid ejected from the bottom

of the housing.

A supply pressure volume 20 extends from the supply pressure port to the

spray channel, as shown in Figures 1 and 2. In a preferred embodiment, the invention further comprises a spray nozzle 29 in fluid communication with the spray

channel, as shown in Figure 5. In the preferred embodiment shown in Figures 1 and 2, a control pressure

port 12 is located in the top of the housing. A pressure barrier 16 forms a seal

which acts as a pressure barrier within the interior of the housing. The pressure

barrier may be a diaphragm extending across the interior of the housing or an

elastomeric member mounted on the metering rod. In a preferred embodiment, the

elastomeric member is an o-ring as show in Figure 1. A control pressure volume

14 is located in the housing above the diaphragm and below the control pressure

port, as shown in Figures 1 -2.

In a preferred embodiment, the o-ring mounted on the metering rod is sized

to form a pressure barrier between the control pressure volume and the supply pressure volume. When the elastomeric member is positioned so as to provide a

pressure barrier between the supply pressure and the control pressure, it is possible to control metering rod movement by varying control pressure. As shown in Figure 1 , the surface area upon which control pressure acts is substantially larger

than the surface area upon which supply pressure acts.

In the embodiment of the invention shown in Figure 2, the movement of the

diaphragm is a function of the differential pressure between the control pressure exerted in the control pressure volume and the supply pressure exerted in the supply pressure volume. In this embodiment of the invention, the control pressure,

supply pressure, and diaphragm provide position control capability for the metering

rod.

The metering rod 22 is centrally located and moveably mounted in the

longitudinal channels. The metering rod extends through the diaphragm as shown

in Figure 2. The metering rod comprises an upper portion in contact with the

diaphragm and a lower portion opposite the upper portion.

In the preferred embodiment of the invention shown in Figure 1 , control

pressure enters the housing through the control pressure port and acts against the

diaphragm, causing it to expand or retract, as a function of control pressure. The

movement of the diaphragm results in axial displacement of the metering rod within

the longitudinal channel. In this embodiment, the control pressure and diaphragm

function as a metering rod driver. A supply pressure port 18 is located in a side of

the housing below the diaphragm.

The embodiment of the invention shown in Figure 1 further comprises at least one spring 36 coupled to the metering rod so as to oppose any downward

acting pressure in the control pressure volume, as shown in Figure 1. The spring

supplies a restoring force which will result in the metering rod being in the retracted position, when the force resulting from the control pressure acting against the

diaphragm is less than the restoring force of the spring.

In another preferred embodiment, the invention further comprises an air port

38 located in a side of the housing opposite from the supply pressure port and an

air channel 40 extending from the air port to the spray channel, as shown in Figure 5. The air port and air channel provide a means for atomizing fluid that is sprayed

from the end of the spray channel. This embodiment of the invention may further

comprise a spray nozzle in fluid communication with the spray channel.

The foregoing disclosure and description of the invention are illustrative and

explanatory thereof, and various changes in the size, shape and materials, as well

as in the details of the illustrated construction, may be made without departing from

the spirit of the invention.

Claims

WHAT IS CLAIMED IS: 1. A variable flow control device, comprising:

a. a housing having a top, a bottom, at least two opposite sides, and a

central longitudinal channel having an upper region and a lower

region; b. a metering rod moveably mounted in said central longitudinal

channel, said metering rod having an upper portion and a lower

portion;

c. a metering rod driver coupled to the upper portion of said metering

rod such that downward movement of said driver results in downward

movement of said metering rod and upward movement of said driver

results in upward movement of said metering rod;

d. a supply pressure port located in a side of said housing;

e. a spray head attached to the lower portion of said metering rod and

mounted in the lower portion of said longitudinal channel, said spray

head having an upper end and a lower end;

f. an expandable spray channel centrally located in said spray head;

and

g. a supply pressure volume extending from said supply pressure port

to said spray channel.

2. The device of claim 1 , wherein said driver comprises: a. a mechanical linkage having a first end coupled to the upper portion

of said metering rod and a second end opposite said first end; and

b. a stepper motor coupled to the second end of said mechanical

linkage.

3. The device of claim 1 , further comprising a spray nozzle in fluid

communication with said spray channel.

4. The device of claim 1 , wherein the lower region of said longitudinal channel

is tapered such that its diameter decreases as a function of distance away

from the bottom of said housing.

5. The device of claim 4, wherein said spray head is sized such that said expandable channel is open when said spray head extends to the bottom

of said housing and said expandable channel is closed as a result of

interference from said tapered longitudinal channel when said spray head is

in a retracted position within said longitudinal channel.

6. The device of claim 5 wherein the lower end of said spray head is tapered

at a substantially similar angle to the angle of the lower region tapering in said longitudinal channel.

A A variable flow control device, comprising: a. a housing having a top, a bottom, at least two opposite sides, and a

central longitudinal channel having an upper region and a tapered

lower region which decreases in cross sectional area as a function of

distance away from the bottom of said housing; b. a control pressure port located in the top of said housing; c. a pressure barrier forming a seal within the interior of said housing; d. a control pressure volume in said housing above said pressure barrier

and below said control pressure port; e. a supply pressure port located in a side of said housing below said

diaphragm; f. a metering rod centrally located and moveably mounted in said

longitudinal channel and extending through said pressure barrier, said

metering rod comprising an upper portion in contact with said

diaphragm and a lower portion opposite said upper portion;

g- a spray head attached to the lower portion of said metering rod and

mounted in the lower region of said longitudinal channel, said spray

head having an upper end and a lower end; h. an expandable spray channel centrally located in said spray head; i. a supply pressure volume extending from said supply pressure port to said spray channel; and

j. at least one spring coupled to said metering rod so as to oppose any

downward acting pressure in said control pressure volume on said

diaphragm.

8. The device of claim 7, wherein said spray head is sized such that said expandable channel is open when said spray head extends to the bottom

of said housing and said expandable channel is closed as a result of

interference from said tapered longitudinal channel when said spray head is

in a retracted position within said longitudinal channel.

9. The device of claim 7 wherein the lower end of said spray head is tapered at a substantially similar angle to the angle of the lower region tapering in

said longitudinal channel.

10. The device of claim 7, further comprising: a. an air port located in a side of said housing opposite from said supply

pressure port; and

b. an air channel extending from said air port to said spray channel.

11. The device of claim 6, further comprising a spray nozzle in fluid communication with said spray channel.

12. The device of claim 7 wherein said pressure barrier is a diaphragm.

13. The device of claim 7 wherein said pressure barrier is an elastomeric member.

14. The device of claim 13 wherein said elastomeric member is an o-ring.

15. A A variable flow control device comprising: a. a housing having a top, a bottom, at least two opposite sides, and a

central longitudinal channel having an upper region and a tapered

lower region which increases in cross sectional area as a function of

distance away from the bottom of said housing; b. a control pressure port located in the top of said housing; c. a pressure barrier forming a seal within the interior of said housing;

d. a control pressure volume in said housing above said pressure

barrier; e. a supply pressure port located in a side of said housing below said

pressure barrier; f. a metering rod centrally located and moveably mounted in said

longitudinal channel and extending through said diaphragm, said

metering rod comprising an upper portion in contact with said

diaphragm and a lower portion opposite said upper portion;

g- a spray head attached to the lower portion of said metering rod and

mounted in the lower region of said longitudinal channel, said spray

head having an upper end and a tapered lower end; h. an expandable spray channel centrally located in said spray head; and i. a supply pressure volume extending from said supply pressure port

to said spray channel.

16. The device of claim 15, wherein said spray head is sized such that said

expandable channel is closed as a result of interference from said tapered

longitudinal channel, when said spray head extends to the bottom of said

housing and said expandable channel is open when said spray head is in a

retracted position within said longitudinal channel.

17. The device of claim 16, wherein the lower end of said spray head is tapered

at a substantially similar angle to the angle of the lower region tapering in

said longitudinal channel.

18. The device of claim 15, wherein said expandable channel extends across

said spray head.

19. The device of claim 15, wherein said pressure barrier is a diaphragm.

20. The device of claim 15, further comprising a spray nozzle in fluid communication with said spray channel.

AMENDED CLAIMS

[received by the International Bureau on 31 March 1999 (31.03.99) ; original claim 15 replaced by amended claim 15 (1 page)] f. a metering rod centrally located and moveably mounted in said longitudinal channel and extending through said pressure barrier, said metering rod comprising an upper portion in contact with said diaphragm and a lower portion opposite said upper portion;

g. a spray head attached to the lower portion of said metering rod and

mounted in the lower region of said longitudinal channel, said spray

head having an upper end and a tapered lower end;

h. an expandable spray channel centrally located in said spray head;

and i. a supply pressure volume extending from said supply pressure port to said spray channel.

16. The device of claim 15, wherein said spray head is sized such that said

expandable channel is closed as a result of interference from said tapered

longitudinal channel, when said spray head extends to the bottom of said

housing and said expandable channel is open when said spray head is in a

retracted position within said longitudinal channel.

17. The device of claim 16, wherein the lower end of said spray head is tapered at a substantially similar angle to the angle of the lower region tapering in

said longitudinal channel.

AMENDED SHEET (ARTICLE 19) STATEMENT UNDER ARTICLE 19

Pursuant to PCT Article 19, please replace claim page 14 with the attached replacement claim page 14. No new matter has been added. Explanation of the amendment made to the claim is attached as Exhibit A.