Vacuum Shut Off Valve Mechanism For A Soil Fumigant Applicator Rig

Abstract

A vacuum shut off valve mechanism for a soil fumigant applicator includes a pneumatic cylinder that is operably connected to respective fumigant dispensing tubes and shanks of the applicator through a flow divider. A pair of switch operated valves respectively control the flow of fumigant to the flow divider and operation of the pneumatic cylinder. In a first switch state a first valve is opened to deliver fumigant to the flow divider and a second valve operates the pneumatic cylinder to pressurize the flow divider and allow delivery of the fumigant to the dispensing shanks. In a second state, the first valve is closed and the second valve operates the pneumatic cylinder to draw a vacuum, which restricts dripping and leaking of residual fumigant from the tubes and dispensing shanks.

Claims

1. A shut off valve mechanism for a soil fumigant applicator rig, said mechanism comprising: a pneumatic cylinder device including an elongate cylinder housing, which housing accommodates a piston slidable in a reciprocating manner through said cylinder housing, said piston separating said cylinder housing into first and second cylinder chambers; a spring biasing said piston into a retracted condition within said cylinder housing; a flow divider communicably interconnecting said first cylinder chamber and at least one fumigant dispensing shank; a first valve communicably interconnecting a source of fumigant and said flow divider, said first valve being selectively opened to introduce fumigant from said source to said flow divider and closed to block the flow of fumigant from said source to said flow divider; a second valve communicably connected to said second chamber of said cylinder housing; and an actuator switch operably connected to said first and second valves, said actuator switch being selectively alternated between a first condition, wherein said first valve is opened and said second valve connects a source of pressurized gas with said second chamber of said pneumatic cylinder to drive said piston through said cylinder housing and increase pressure within said second chamber of said cylinder housing and said flow divider such that fumigant is dispensed through each fumigant dispensing shank, and a second condition wherein said first valve is closed and said second valve vents said pressurized gas from said second chamber of said cylinder housing such that said spring drives said piston into said retracted condition, which draws a vacuum within said first chamber and said flow divider to shut off dispensing of fumigant by each dispensing shank of the rig.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Other objects, features and advantages will occur from the following description of a preferred embodiment and the accompanying drawing, in which:

[0022] FIG. 1 is a schematic view of the vacuum shut off valve mechanism in accordance with this invention with the ON/OFF switch in an OFF condition to prevent dripping or leaking of fumigant from the dispensing shanks; and.

[0023] FIG. 2 is an elevational schematic view of the vacuum shut off valve mechanism with the ON/OFF switch in the ON condition for delivering fumigant to the dispensing shanks and injecting such fumigant into the soil.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

[0024] There is shown in FIGS. 1 and 2 a vacuum shut off valve mechanism 10 for use on a soil fumigant applicator rig. Although mechanism 10 is especially suited for functioning effectively and achieving improved results in conjunction with a soil fumigation rig, the mechanism may also be used for alternative liquid shut off valve applications within the scope of this invention. In addition, mechanism 10 can be used effectively with virtually all types of soil fumigants with the exception of methyl bromide. The mechanism also may be employed with fumigation rigs and fumigant applicators of all types and in virtually any planting or crop application.

[0025] The fumigation applicator rig, which is a standard machine and not shown, carries a supply of fumigant 11 that is delivered through a fumigant supply conduit 12 to a flow divider 14. In particular, an outlet end of supply conduit 12 is connected via an inlet fitting 16 to flow divider 14. The flow divider is a conventional item that may include various types of known construction for directing fumigant 11 to individual fumigant transmitting tubes 18. The fumigant transmitting tubes 18 are, in turn, connected to fumigant dispensing shanks 19 mounted to the rig in a conventional manner. It should be understood that the construction of the shanks and the tubes, as well as the means for interconnecting these components and mounting them to the rig are standard and will be understood to persons skilled in the art. In addition, it should be understood that although four tubes 18 and respective shanks 19 are depicted herein, any alternative number of tubes and shanks may be utilized within the scope of this invention. Flow dividers may be constructed according to known principles to distribute and direct the flow of fumigant to the number of tubes and respective shanks that are utilized by the rig.

[0026] Mechanism 10 critically employs a vacuum producing pneumatic cylinder device 20 that is operably connected to flow divider 14 by a cylindrical fitting 22. Pneumatic cylinder device 20 includes an elongate stainless steel cylinder housing 24 having a lower first end 26 and an opposite upper end 28. In certain preferred embodiments of this invention, the pneumatic cylinder may have a bore of 1.5 and a stroke of 3, although these specifications may be modified within the scope of the invention. A piston 29 operably mounted within the cylinder housing includes a piston head 30 and an attached piston rod 32, which extends upwardly from piston head 30 and through a sealed opening 34 in upper end 28 of cylinder housing 24. As described below, piston head 30 travels longitudinally through cylinder housing 24 and divides the cylinder housing into a first lower chamber 25 and a second upper chamber 27.

[0027] A Viton head seal or alternative seal appropriate for use in pneumatic cylinders is carried by piston head 30 to sealably interengage the interior walls of cylinder housing 24. A nut 36 defining a spring retention element is threadably or otherwise secured proximate an upper end of piston rod 32. A helical compression spring 40 is wound about the exterior upper portion of piston rod 32. Spring 40 extends between the top surface of upper end 28 of cylinder housing 24 and element 36. Spring 40 forms a piston retractor spring for driving the piston into a retracted condition during operation of the valve mechanism. This operation is described more fully below.

[0028] Mechanism 10 utilizes first and second valve components 50 and 60, which are in turn controlled by an ON/OFF switch 70. Valves 50 and 60 thereby control both delivery of fumigant to flow divider 14 and operation of pneumatic cylinder 20. In accordance with this invention, pneumatic cylinder 20 generates a vacuum that controls dripping and leaking of fumigant from the individual fumigant transmitting tubes 18 and attached shanks 19.

[0029] First valve component 50 comprises a two-way KZ valve for selectively opening and closing fumigant supply line 12. As previously indicated, valve 50 is electrically operated by ON/OFF switch 70. Various alternative types of solenoid valves may be employed. Opening valve 50 causes fumigant to be delivered to flow divider 14 as further described below.

[0030] Second valve 60 comprises, for example a three-way KZ valve. Again, valve component 60 is alternated between different states by operation of ON/OFF switch 70. Various other solenoid valves may be employed within the scope of this invention. Valve 60 includes first, second and third ports 62, 64 and 66, respectively. First port 62 is communicably connected through a pipe 63 to an inlet/outlet fitting 65 of cylinder housing 24. The inlet/outlet fitting 65 is in turn communicably connected with the upper second chamber 27 of cylinder housing 24. Second port 64 of valve component 60 is communicably connected to a pressurized nitrogen supply 67. The gas has a pressure of about 150 lbs. although other pressures sufficient for operating the pneumatic cylinder in a manner as described below may be employed within the scope of this invention. In addition, although nitrogen is disclosed as the preferred pressurizing gas, alternative gases may be utilized. Port 64 may be joined to pressure source 67 by appropriate piping and fittings. A pressure gauge 69 may be employed to indicate the gas pressure of supply 67.

[0031] Third port 66 defines a vent 72. Various pipes and fittings may be inserted in to port 66 to form the vent. Alternatively, the port itself may define the vent. Second valve 60 operates schematically as best depicted in FIG. 2. Specifically, in a first or ON state, an internal valve closure element 74 is positioned so that ports 62 and 64 are communicably connected, whereas port 66 is disconnected from ports 62 and 64. Alternately, in the OFF position shown in phantom, closure element 74 is positioned so that ports 62 and 66 are communicably interconnected and port 64 is disconnected from port 62 and 66.

[0032] Mechanism 10 may be mounted in any acceptable manner within the fumigation rig or other apparatus for which mechanism 10 is used. The particular details for mounting the system or arranging components of the system on the applicator rig may be varied within the scope of this invention and should be understood by persons skilled in the art. ON/OFF switch 70 should be positioned on the rig so that it is conveniently accessible to the operator. Various known types of electrical or alternative switches may be employed. Switch 70 is alternated between ON and OFF conditions or open and closed states to alternately dispense fumigant from the rig or operate the shut off valve mechanism so that dripping and leaking of retained fumigant from the transmission tubes 18 and fumigant dispensing shanks 19 is controlled.

[0033] In operation, switch 70 is turned ON to dispense fumigant and treat the field. In particular, in the ON condition, switch 70 directs valve component 50 to open fumigant supply line 12. As a result, as best shown in FIG. 2, fumigant 11 is delivered through supply line 12 and open two-way valve 50 to flow divider 14. At the same time, switch 70 directs three-way valve 60 to operate valve closure 74 in the manner shown in FIG. 2 such that pressurized nitrogen gas 67 is delivered through piping 78 to port 64 of valve 60. Ports 64 and 62 are communicably interconnected, as shown, so that the pressurized nitrogen gas proceeds as indicated by arrows 82. In particular, the nitrogen gas enters upper second chamber 27 of pneumatic cylinder housing 20 through inlet/outlet 65. The 150 lbs. of gas pressure overcomes the 40 lbs. resistance of spring 40. As a result, piston 29 is driven longitudinally and downwardly through cylinder housing 24 against spring 40, which compresses. Lower chamber 25 of pneumatic cylinder 20 is pressurized and this pressure increase is transmitted by fitting 22 to flow divider 14. As a result, fumigant is directed through tubes 18 in the manner shown in FIG. 2 to dispensing shanks 19. The delivered fumigant is thereby dispensed by the shanks into the soil of the agricultural field being treated.

[0034] When the fumigation rig reaches the end of a row or pass across the field and is turning or, alternatively when operation of the rig is temporarily halted or the fumigant application process has been completed, the operator turns switch 70 off. The ON/OFF switch thereby directs two-way valve 50 to close so that no further fumigant is delivered through supply conduit 12 to flow divider 14. In this state, mechanism 10 operates to shut off the discharge of any extra or residual fumigant remaining in tubes 18 and/or in the dispensing shanks. Specifically, switch 70 directs three-way valve 60 to operate so that closure 74 assumes the position shown in phantom in FIG. 2. First port 62 of valve 60 is thereby communicably joined to vent 72 formed in port 66. Port 64 is closed and the pressurized nitrogen supply 67 is effectively blocked from port 62 and 66. As a result, as best shown in FIG. 1, upper or second chamber 27 of pneumatic cylinder 20 is vented to the atmosphere. As indicated by arrows 92, nitrogen gas is allowed to escape from chamber 27 through inlet/outlet fitting 65, pipe 63, port 62 and communicably open vent 72. Release of the pressurized gas from the pneumatic cylinder is facilitated by operation of the retraction spring, which expands from the compressed position shown in FIG. 2 to the retracted condition shown in FIG. 1. Piston 29 is thereby retracted upwardly within cylinder housing 24 and a vacuum V is drawn within lower, first chamber 25. This vacuum is applied to the fumigant remaining in tubes 18 through flow divider 14. At least some of the remaining fumigant is drawn into first chamber 25. The stainless steel construction of the pneumatic cylinder 20 and flow divider 14 enables those components to resist corrosion and damage from the fumigant drawn into the cylinder. The vacuum drawn by pneumatic cylinder 20 thereby securely holds the fumigant remaining in tubes 18 and dispensing shanks 19. Arrows 94 in FIG. 1 depict the negative pressure effectively drawing the fumigant upwardly through the tubes. The vacuum pressure is sufficient to shut off further discharge and prevent any dripping or leaking of residual fumigant from the tubes or the shanks.

[0035] The individual components of this invention may be constructed of durable metals and plastic materials of the type commonly used for fumigant application equipment. The pneumatic cylinder may include a SpeedAire pneumatic cylinder or comparable device.

[0036] The switch may be interconnected with the first and second valves in alternative ways within the scope of this invention. For example, the switch and valves may be assembled and constructed so that in an OFF state the fumigant is dispensed and in an ON state dripping and leakage of residual fumigant from the tubes and shanks is shut off.

[0037] The vacuum shut off mechanism of this invention works reliably, completely and virtually instantaneously to prevent unintended and problematic dripping and leaking of fumigant from the tubes and shanks of a fumigation rig or applicator. Dripping is controlled by simply activating the ON/OFF switch as each pass across the field is concluded, during turns and other times when operation of the applicator is halted and further dispensing of fumigant is not desired. As a result, a number of benefits are provided. Irritating and potentially harmful, noxious chemicals are not dripped onto the field. Workers experience far less irritation to their eyes, nose and throat and fewer respiratory problems. Elimination of fumigant dripping also reduces premature corrosion of brass shanks, metal tubes and other components of the fumigation rig. Operational delays and costly repairs are also minimized. Far less product is wasted, which also saves considerable expense.

[0038] While this detailed description has set forth particularly preferred embodiments of the apparatus of this invention, numerous modifications and variations of the structure of this invention, all within the scope of the invention, will readily occur to those skilled in the art. Accordingly, it is understood that this description is illustrative only of the principles of the invention and is not limitative thereof.

[0039] Although specific features of the invention are shown in some of the drawings and not others, this is for convenience only, as each feature may be combined with any and all of the other features in accordance with this invention.