US2800365A - Spraying system with drip preventing means - Google Patents

Description

July 23, 1957 L. s. HODGES ,8

SPRAYING SYSTEM WITH DR IP PREVENTING MEANS Filed Nov. 16, 1953 2 Sheets-Sheet 1 PUP w 1 m pump SPRAY/N6 & 2 70 IVOZZLES 4/ INVENTOR. LEO/144140 S/ACL/I/A #00655 OUTLET I W457 BY F 741w asomzzo S :YTTORIVEYS.

ates

Leonard S. Hodges, Leamington Spa, England, assignor to Massey-Harris-Ferguson (Sales) Limited, a British corn- P y Application November 16, 1953, Serial No. 392,405

Claims priority, application Great Britain November 19, 1952 2 Claims. (Cl. 299--$) The present invention relates in general to spraying systems and, more particularly, to controls for spraying systems of the type adapted to prevent dripping of liquid from lines and nozzles when spraying is stopped.

The general aim of the invention is to provide a spraying system for discharging liquid from a source through a nozzle by means of a pump, in which the positive action of the pump is utilized in a novel manner to provide sucking action to prevent dripping or loss of liquid present in the nozzles or lines when the spraying operation terminates.

It is another object of the invention to provide in such a system a single control valve for effecting spraying through the nozzle or connection of the pump for preventing dripping of liquid.

A further object of the invention is to provide such a system utilizing a gear-type pump in which the control valve is selectively movable to three positions to (a) permit spraying, ([2) permit the pump to return liquid in the nozzle, and its conduit to the source, and (c) shut off lines and prevent seepage through the pump when the latter is idle.

Still another object is the provision of an improved spraying system of the foregoing type in which a check valve is utilized not only as a safety means to prevent excessive pressure, but also to cooperate with a single valve which need be movable between only two positions accomplishing the action described.

Other objects and advantages will become apparent as the following description proceeds, taken in conjunction with the accompanying drawings, in which:

Figure l is a diagrammatic representation of a first embodiment of a spray system having the features of the present invention;

Figs. 2, 3, and 4 are sectional views of a control valve employed in the spray system, showing the movable element of the valve in the three respective positions;

Fig. 5 is similar to Fig. 1, illustrating a second and preferred embodiment of the invention; and Figs. 6 and 7 are sectional views of the control valve in Fig. 5, showing the movable element in its two controlling positions, respectively.

While the invention has been illustrated and is described in some detail with reference to particular embodiments thereof, there is no intention that it thus be limited 0t such detail. On the contrary, it is intended here to cover all alterations, modifications and equivalents falling within the spirit and scope of the invention as defined by the appended claims.

Referring now to Figs. 14, the exemplary spraying system here illustrated in accordance with the invention is intended to dispense liquid from a source 16 through one or more discharge nozzles 11., 12 and 13. For accomplishing such discharge, a pressure generator or pump 14 is provided and adapted to be driven by any suitable means.

By way of example, the system may be of the type atent- 0 2,800,365 Patented July 23, 1957 mountable on the rear of a tractor, the pump 14 being driven from the tractors power take-off shaft (not shown), and the nozzles 11, 12 and 13 being disposed to spray liquid insecticide on plants as the tractor advances. Preferably, therefore, the source 16 is in the form of a suitable liquid container or tank adapted to be carried on the rear of the tractor.

In order to provide for efficient and positive pressurization of the liquid to be discharged, the pump 14 is desirably of the gear or positive displacement type, having an inlet 15 and an outlet 16. For safetys sake, a pressure relief valve 17 is connected between the pump outlet 16 and the tank 10 by means of conduits 19 and 20. Such relief valve is of the well known ball type, having a spring 18 which permits the discharge. of liquid from the outlet 16 back to the tank 10 when the outlet pressure exceeds a predetermined value. Any clogging of the lines or discharge elements, therefore, causes no damage to the system as the result of unduly great pressures.

As shown in this instance, the three spray nozzles 11,

12 and 13 are in the form of hollow, horizontal booms apertured at points spaced along their lengths to provide a plurality of spray jets indicated at 21. The three nozzles 11, 12 and 13 are shown connected in parallel, with cut-off valves 22, 23 for the latter two so that the central nozzle 11 may be operated alone, with either of the outboard nozzles 12 or 13, or with both of the outboard nozzles. It will be understood, however, that one or more nozzles may be employed as desired and that they may take different forms. For example, in lieu of the boom-type nozzle 11, a projecting type nozzle may be employed at the end of a length of flexible hose for spraying fruit trees and the like as the tractor is driven between them.

In accordance with the present invention, a single control valve 25 is provided for alternatively connecting the pump to transfer liquid from the tank to the nozzles, or to suck liquid from the nozzles and their connecting lines when their spraying operation is terminated. Since the control valve is normally located at a relatively great distance from the nozzles, for example, near the drivers seat on a tractor carrying the nozzles near the ground, this prevents the dripping which would otherwise occur. Further, the positive action of the pump is employed to prevent such dripping, the liquid thereby being returned to the tank. Complete control is obtained through the positioning of but a single valve element.

As here embodied, the control valve 25 (Figs. 24) includes a hollow housing 26 having four ports 30- 33 defined in its wall. In the present instance, the four ports are arranged in diametrically opposed pairs 36), 32 and 31, 33, each port being spaced degrees from the adjacent one around the periphery of the cylindrical cavity 35 in the housing 26. For establishing selective communi cation between the ports 3033, a movable valve member 36 is located in the cavity 35 and formed to include diametrically opposed lands 33 and 39, bearing against the inner wall of the housing in sealing relation. The valve member 36 is rotatable and may be angularly positioned by means of a suitable handle 37 (Fig. 1) extending through the housing 26, the valve element thus being selectively located in any of the three controlling positions illustrated respectively by Figs. 2, 3, and 4. In any of its positions the valve element 36 is adapted to substantially bisect the cavity 35 in the housing 26 and thus, as in Figs. 2 and 3, to selectively connect adjacent ones of the ports 30-33 or to block either pair of opposed ports 30, 32, or 31, 33.

The system is completed by conduits including a line 40 connecting the first port 30 with the tank 10, a line 41 connecting the second port 31 with the pump inlet 15,

3 a line 42 connecting the third port 32 with the discharge nozzles 11-13, and a line 43 connecting the fourth port 33 with the pump outlet 16;

In order to prevent clogging of the nozzles, afilter'45 is preferably interposed in the line '43 to trap sediment and other foreign material. -Also, in order that the systern may be op'eratedat the desired;pressure; a 'p'ressure gauge 46 is connected with the. pump outlet 16 and disposed at a point where it may be conveniently observed.

In the operation of the present spraying system, the pump 14 is driven continuously and the valve member 36 selectively positioned to start or stop spraying, With the valve member 36 positioned as shown in Fig. 2, fluid is supplied from the tank 10 through the nozzles li f-13 as indicated by the solid flow arrows in Fig. 1. More specifically, fluid is drawn from the tank 19, through the line 40, port 30, the cavity 35, port 31, line 41, through the pump inlet 15 and out of the pump outlet 16, thence through the filter 45 and line 43 to the port 33, through the cavity 35 and out the port 32 to the nozzles 1113. During this spraying operation the pump by virtue of its positive displacement gear arrangement, supplies the fluid under proper pressure to the nozzles. However, in the event the pressure at the pump outlet should become unduly great, the pressure relief valve 17 opens to allow venting of pressured fluid back to the tank 10 through line 20. r

In order to terminate the spraying, the valve member 36 is rotated through approximately 90 degrees to p sition illustrated in Fig. 3. This places the ports 31 and 32, and the ports 33 and 30, in communication with one another, establishing the liquid flow paths indicated in Fig. 1 by the dashed arrows. Dripping of liquid trapped in the nozzles 11-13 and lines 42 is prevented by positive pumping action sucking such liquid back through the port 32, the port 31, the pump inlet and outlet 15 and 16, the line 43, the ports 33 and 3t), thence through the line 40 into the tank It). No seeping or dripping of the liquid can therefore occur, although the anti-drip action or return of the fluid in the nozzles is accomplished simply by the operator switching the valve member 36 from one position to another.

It will be readily apparent, also, that with the valve in the position shown by Fig. 3, liquid may be drawn from a creek, pond or other natural source up into the tank 10. The water thus sucked into the tank 10 may, for example, be mixed with suitable insecticides and sprayed by the system as previously described.

While the use of the impeller or gear type pump 14 has many advantages in that it provides positive displacement, requires little maintenance, and may be continuously driven or operated dry. Nevertheless it is possible that when the pump is idle, and with the valve element 36 positioned as shown in either Fig. 2 -or Fig. 3, some liquid may be lost by gravity flow and seepage through a pump of this type. For example, with the valve in the position illustrated by Fig. 3 it would be possible for some liquid to seep in directions opposite to those shown by the dashed arrows over the liquid flow path described above for the anti-drip operation. In order to prevent such leakage when the pump is idle and the spraying system not in use, the valve element 36 need only be moved to the third position shown in Fig. 4. In such position, the lands 38 and 39 effectively block the ports 30 and 32. No liquid can thus be discharged from the line 40 and the tank 10. With the tank thus isolated, the system may be left in storage indefinitely without loss of fluid from the tank.

Turning now to the preferred embodiment 'of the invention shown in Figs. 5-7, the spray system there shown is generally similar to that described above. Parts corresponding to those appearing in Fig. 1 are identified by the same reference characters in Fig. 5,,except for the addition of the distinguishing aifix fa.. The principal modification in the preferred embodiment'lies in the Or ani t i. th a ts?! .Yt ltn 5.a h as lt m operation} by means of which the outlet of the tank is sealed off during the sucking operation. This enables the system to be completely controlled simply by moving the valve element 36a between only two positions, as distinguished from three positions in the embodiment first described.

In this instance, the ports 30a-33a in the valve housing 26a are not disposedsymmetrically at ninety degrees around the cylindrical cavity. Instead, they are asymmetrically clustered at relative angular spacings less than ninety degrees. As here shown, the first, second, third, and fourth ports 30a, 31a, 32a, and 33a are circularly spaced at approximately seventy-four degrees around the valve housing 26, thus leaving a large wall portion 50 subtending at an angle greater than ninety degrees between the ports 33a and 30a; The remaining ports are separated by wall portions 51--53 of relatively small angular extent.

For cooperating with this modified valve housing, a movable valve member 36a is disposed therein, having opposed asymmetric lands 38a and 39a slidably bearing against the housing wall in sealing relation therewith. The lands 38a, 39a are diametrically opposed but the former extends over a greater are so as to bear against the wall portion 50 when the member 36a is rotatably positioned as in Fig. 6, By virtue of this arrangement, the movable member 361): may be positioned to place the ports 30a and 31a and the ports 32a and 33a in direct communication (Fig. 6), or to connect the ports 31a and 32a while blocking the port 30a and cutting the port 33a off from communication with the others (Figs. 7). In the first position, spraying is accomplished as described in connection with the first embodiment, while in the second position of the element 36a the pump 14a serves to positively suck fluid from the nozzles 11a-13a and push it back into the tank 10a.

More explicitly, for spraying, the valve is positioned as shown in Fig. 6 so that liquid flows from the tank over the paths indicated by the solid flow arrows in Fig. 5, that is, through the line 40a, the ports 3011 and 31a, the pump 14a, the line 43, the ports 33a and 32a, and thence to the nozzles Ila-43a.

On the other hand, with the placement of the valve element 36a as shown in Fig. 7, the ports 31a and 32a are directly connected, permitting fluid to be sucked by the pump 1411 from the nozzles 11a'13a and discharged from the outlet 16a, through the pressure relief valve 17a and the line 20a back to the tank 10a. The land s-sa of the valve element 36a positively blocks the port 30d and prevents seepage of fluid from the tank through the line 40a even though the pump is idle. Thus, once the spraying has been terminated and liquid withdrawn from the nozzles, the pump may be left idle with no danger of loss of liquid from the tank without repositioning the valve element 36a to a third position as described in the case of the first embodiment. The pressure relief valve 17a thus serves the dual purpose of providing safety against unduly great pressure at the pump outlet during the spraying operation, and also of providing a return path for liquid pumped from the nozzles hack to the tank 10a in the prevention of dripping. Because the valve element 36a in its second position (Fig. 7), cuts off the port 33a from communication with any of the others, the pressure at the outlet of the pump builds up to a value sufliciently great to open the relief valve 17a when liquid is being withdrawn from the nozzles.

From the foregoing, it will be apparent that the present invention provides a spraying system which is simple in its organization and construction, yet which provides for the positive return of liquid left in the nozzles and nozzle lines when a spraying operation is terminated. -No loss of liquid due to dripping occurs. Secondly, such operation is achieved in a system utilizing a gear-type pump which has many advantages but which, nevertheless, may permit some liquid to seep through its working parts when it is idle. By the present invention, seepage through the pump and loss of liquid through the nozzles when the pump is idle are precluded by positioning the same valve which controls the spraying and anti-drip operations. In the preferred embodiment such advantageous control is accomplished by a valve which need only be moved between two selected positions, a oneway pressure-sensitive relief valve being employed both as a safety device for the system and as means for permitting this operation.

I claim as my invention:

1. In a spraying system, the combination of a liquid supply tank; a discharge nozzle; a gear pump having an inlet and an outlet; a spring biased pressure relief valve connected between said outlet and tank to permit liquid flow from the former to the latter under pressure above a predetermined value; a control valve including a cylindrical housing having first, second, third, and fourth ports defined through its wall, said ports being spaced in the order named at intervals in the order of 74 degrees around the periphery of said housing leaving a wall portion subtending an angle greater than 90 degrees between said first and fourth ports; conduit means connecting said tank, inlet, nozzle and outlet to the respective ports in the order named; and a valve member in said housing rotatable between two angular positions, said member having opposed, asymmetrical lands the larger of which is adapted to bear against said wall portion when the smaller bears against said wall between said second and third ports in the first position, the larger land covering said first port and engaging the wall between said third and fourth ports when said member is in its second position.

2. In a spraying system, the combination of a liquid supply container; a discharge nozzle; a pump having an inlet and an outlet; at pressure relief valve for permitting liquid to flow from said outlet to said container; a control valve including a cylindrical housing having first, second, third and fourth ports through the walls thereof, said ports being asymmetrically located in the order named about the periphery of said housing leaving an angle greater than degrees between the fourth and first ports; conduit means connecting said container, inlet, discharge nozzle, and outlet to respective ones of said ports in the order named and a rotatable member in said housing movable between two angular positions relative thereto, said rotatable member having asymmetrical lands bearing against the Wall of the housing to connect selectively (1) the first and second ports and the third and fourth ports, and (2) the second and third ports while blocking the first and fourth ports; whereby liquid is pumped from said container through said discharge element in the first instance, and is pumped from said discharge element through said relief valve to said container in the second instance.

References Cited in the file of this patent UNiTED STATES PATENTS 1,755,376 Thompson Apr. 22, 1930 1,809,432 Webb June 9, 1931 2,145,132 Riney Jan. 24, 1939 2,650,003 Coleman Aug. 25, 1953

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