IMPROVED VALVE-CONTROLLED SPRINKLER SYSTEM.

Abstract

A liquid spray system comprising a liquid spray section and a controller for regulating the liquid flow to the spray section. The controller includes a multi-position valve to control the liquid supply to the spray section and to allow liquid to flow from the spray section to a recovery line only after the liquid supply to the spray section has ceased.

Description

IMPROVED VALVE-CONTROLLED SPRINKLER SYSTEM FIELD OF INVENTION The present invention relates generally to valve-controlled spraying systems, and more particularly to an improved valve system for controlling the liquid flow to spray nozzles during operation and at the time of shutting off a liquid supply. BACKGROUND OF THE INVENTION Agricultural sprayers typically have long spray booms with groups of spray nozzles that are selectively controlled by individual control valves. Each control valve is individually actuated to allow the flow of liquid to be transmitted or terminated to the spray nozzles within the group. Terminating the liquid flow to one or more groups of spray nozzles is often necessary, for example, near field edges to prevent spraying on non-agricultural vegetation or similar areas. The control valves for such spraying systems are commonly mounted side-by-side, grouped or clustered with respect to one another and away from the spray nozzles they control. Each control valve is equipped with a valve element that moves between open and closed positions to selectively control the flow of liquid to the spray nozzles within the respective group. Control valves are known to include a rotary ball valve that rotates between a position that allows pressurized fluid to flow through the control valve to the fluid supply line to the spray nozzle or nozzle groups, and a second position that closes a fluid inlet port on the valve and redirects the remaining fluid downstream to a return line for recirculation to a fluid supply tank. During the rotary movement of the ball valve to a closed position, however, the fluid inlet port does not completely close before opening a port to the return line, resulting in high-pressure fluid spurting through the control valve before the inlet port fully closes.In today's sophisticated agricultural sprinklers, the liquid applied to the field is often monitored by the amount of liquid directed to the spray nozzles, and the redirection of liquid to the return line before the valve closes can affect the accuracy of monitoring chemical usage. Although proposals have been made to prevent this, they have been relatively complex and expensive, requiring multiple valve mechanisms. BRIEF DESCRIPTION OF THE INVENTION One objective is to provide a valve-controlled sprinkler system that allows for more efficient and accurate monitoring of the liquid supplied to the sprinkler based on the IVIA / a / ZUZZ / UI UUU I liquid inlet feed. Another objective of the present invention is to provide a valve-controlled spraying system as previously described, which operates to shut off the liquid supply to the spray nozzles without unwanted jets of liquid through the control valve that could affect the accurate monitoring of chemical usage. An additional objective is to provide a valve-controlled sprinkler system of the above type having an operative liquid supply control valve to completely shut off the liquid supply to the sprinkler nozzles before permitting the direction of liquid downstream in the sprinkler nozzle feed lines to a return line to the liquid supply. Another objective is to provide a valve-controlled system of the above type that is relatively simple in construction and operation and lends itself to economical manufacture and reliable use. Other objectives and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which: BRIEF DESCRIPTION OF THE FIGURES Figure 1 is an illustrative schematic diagram of a sprinkler system having control valves according to the present invention; Figure 2 is an enlarged fragmentary section of one of the spray nozzle assemblies and its associated check valve included in the spray system shown in Figure 1, showing the check valve in a closed position; Figure 3 is an enlarged fragmentary section of the illustrated check valve, showing the check valve in an open position; Figure 4 is an enlarged vertical section of one of the illustrated control modules taken in a plane perpendicular to a central liquid port of the control module showing the valve stem of the same in an open position to communicate liquid from the central liquid supply port to an outlet port of the control valve; Figure 5 is a vertical section, similar to Figure 4, but showing the valve stem in a lowered position that blocks the flow of liquid from the liquid supply port to an outlet port to the spray nozzles while opening a return or recovery port communicating with a return line; Figure 6 is a vertical section of the control module shown in Figure 5 taken in a plane perpendicular to that of Figure 5; Figure 7 is a partial section of the control module, similar to Figure 4, showing the valve stem in an open position allowing liquid communication through an outlet port to spray nozzles; UUU I Figure 8 is a figure similar to Figure 7, but showing the valve stem in an intermediate position that blocks the flow of liquid to both the liquid outlet port to the spray nozzles and the return or recovery port of the module; Figure 9A is a partial section similar to Figures 5 and 6, showing the valve stem in a lowered position blocking the flow of liquid through the inlet port and allowing return flow of liquid to a return or recovery port; Figure 9B is an enlarged pop-up of the lower valve stem in Figure 9A; Figure 10 is an enlarged perspective of the electric motor drive and valve stem of the illustrated control module; Figure 11 is an enlarged horizontal section of the control module taken in the plane of line 11-11 in Figure 7; Figure 12 is a side elevation view of the electric motor drive and valve stem of the illustrated control module; and Figure 13 is a section of the motor drive and valve stem taken in the plane of line 13-13 in Figure 12. Although the invention is susceptible to various modifications and alternative constructions, a certain illustrated embodiment thereof has been shown in the drawings and will be described in detail below. However, it should be understood that there is no intention to limit the present invention to the disclosed structural form. On the contrary, the intention is to encompass all modifications, alternative constructions, and equivalents that fall within the spirit and scope of the invention. Therefore, although the present invention will be described in connection with group-mounted control valves for an agricultural sprinkler system, it will be understood that the invention is equally applicable to control valves for other types of liquid spraying or transfer systems. DETAILED DESCRIPTION OF THE INVENTION Referring now more specifically to Figure 1 of the drawings, an illustrative agricultural sprinkler system 10 is shown, comprising a supply tank 11 for holding a quantity of liquid to be sprayed, a plurality of sprinkler sections 12, each having a plurality of sprinkler nozzles 14 through which liquid is discharged, and a group of sprinkler control valves 15 according to the invention, which are mounted in a grouped or clustered side-by-side relationship with respect to each other and are adapted to control the flow of liquid from the supply tank 11 to the sprinkler sections 12. Essentially, the sprinkler system 10 is similar to that disclosed in U.S. Patent 6,036,107, referenced above, which is incorporated herein by reference. As is typical in agricultural sprinklers, the 10 sprinkler system includes a IVIA / a / ZUZZ / UI UUU I supply line 18 between supply tank 11 and control valve group 15 to transmit liquid to control valves 15, a discharge line 19 between each control valve 15 and a respective spray section 12 to deliver liquid to the spray section 12, a return line 20 providing return communication between control valves 15 and supply tank 11, and a regulating line 21 having a regulating valve 22 between control valve group 15 and supply tank 11 to facilitate system pressure regulation. The supply line 18 of the polished sprinkler system 10 includes a shut-off valve 24, which allows manual interruption of the liquid flow from the supply tank 11; a pump 25, which pressurizes the liquid in the supply line 18; a strainer 26, which filters debris from the supply line 18; and a throttle valve 28, which allows manual flow regulation. The supply line 18 also includes a return line 29, which branches off from the supply line 18 at a point downstream of the pump 25 and returns to the supply tank 11. As shown in Figure 1, this return line 29 includes an agitator 30 located inside the supply tank 11, which mixes the liquid within the supply tank 11 based on the flow rate through the return line 29.A throttling valve 31 is also provided in the return line 29 which can be manually adjusted to regulate the flow rate through the return line 20 and adjust the mixing rate of the agitator 30. The illustrated spray system 10 is provided with a computer-operated sprinkler control 35 which is operatively connected to each of the group's control valves 15 and regulating valve 22, in a known manner. The illustrated spray nozzles 14, as shown in Figures 2 and 3, may be of a conventional type, in this case each having a nozzle body 38 with a stem 39 supported in fluid communication with a liquid supply riser 40 of the spray section 12, which in turn is coupled to a respective supply line 19. The spray nozzles 14 have a respective check valve 41, as disclosed in Commonly Assigned United States Patent 4,660,598, the disclosure of which is incorporated herein by reference in its entirety.When the liquid pressure supplied to the spray nozzle 14 through the supply line 19 exceeds the force of a deflection spring 42, the pressurized liquid pushes a diaphragm 45 away from an upstream end 46 of an inlet tube 48, as shown in Figure 3, to allow the liquid to flow through the inlet tube 48 and be discharged from the spray nozzle. Upon shutting off the pressurized liquid from the supply source, the spring 42 pushes the diaphragm into a sealed coupling with the upstream end of the tube 48 to prevent additional liquid from discharging or dripping from the spray nozzle 14. The control valves 15 of the spray sections 12 have a modular construction and are mounted in a grouped or clustered relationship in a manner similar to that disclosed in U.S. Patent 6,036,107 referenced above. The control valves 15, as shown in Figures 4-6, have a main valve body 50, a lower valve body 51 supported dependently with the main valve body 50, and an electric valve control motor 52 supported above the main valve body 50.The main valve body 50 in this case has an upward-opening annular collar 54 that receives and supports an annular mounting section 55 of an engine housing 52 with annular sealing rings 56 in between, and the lower valve body 51 has an upward-extending, reduced-diameter hub section 58 supported within a lower end of the main valve body 50 with a sealing O-ring 59 in between. The main valve body 50 includes a centrally oriented, transversely oriented main fluid supply port 60 for receiving fluid from the supply line 18, and the lower valve body 51 has a centrally oriented, vertical fluid passage 62 for communication with the fluid supply port 60.The central vertical passage 62 in turn communicates with a transverse passage 64 having a liquid outlet port 65 and a reduced downstream return or recovery port 66 adjacent to a lower end of the valve body 51. The control valves 15 are grouped with the liquid supply ports 60 of the plurality of control valves communicating with each other and with the liquid supply line 18, and with each liquid outlet port 65 being coupled to a respective liquid supply line 19 to a spray section 12 and each liquid return or recovery port 66 coupled to the return line 20. According to an important feature of the present embodiment, each control valve 15 has a single valve stem 70 to control the flow of liquid from the main liquid supply port 60 to the outlet port 65 and the respective supply line 19 and to the liquid return or recovery port 66 and the return line 20. For this purpose, the valve stem 70 extends centrally through the main valve body 50, the liquid supply port 60, and the central liquid supply passage 62 of the lower valve body 51. The valve stem 70 in this case extends the length of the main and lower valve bodies 50, 51 with a lower end thereof being able to be placed through a lower return or recovery port 66.An annular seal 71 is supported around a lower end of the valve stem 70 (Figure 9B) for sealed contact with the reduced-diameter return or recovery port 66, as will be apparent. For ease of manufacture, the valve stem 70 in this case has upper and lower sections 70a, 70b secured together by means of a threaded coupling 72. To control the liquid supply from the liquid supply port 60 to the central passage section 62 and an outlet port 65 of each spray nozzle 14, an annular seal 75 is supported on the stem 70 within the main liquid supply port 60, as shown in Figure 4. The main annular seal 75 is deflected downward against an E-pin 76 fixed to the stem 70 by means of a coil spring 78 interposed between a washer 79 on an upper side of the annular seal 75 and an upper E-pin 80 fixed to the stem a distance above the washer 79. An O-ring seal 81 is mounted in surrounding relation to the valve stem 70 within the annular seal 75. To raise and lower the valve stem 70 between open and closed positions, the electric motor 52 is operatively coupled to the valve stem 70. For this purpose, the electric motor 52 can be a 12 V DC, reversible motor, having a drive shaft 85 coupled to a drive train 86 to rotate an output shaft 88 supported in a dependent relationship with the drive train 86 above the valve stem 70. To facilitate the controlled raising and lowering of the valve stem 70 as an incidental to the rotation of the output shaft 88, an optical switch indicator 89 fixed to an upper end of the valve stem 70 is threaded onto a threaded section 90 of the output shaft 88.The switch indicator 89 is held against rotation so that driven rotation of the output shaft 88 will cause the switch indicator 89 and the valve stem 70 coupled to its lower side to be raised or lowered relative to the valve bodies 50, 51. To guide the raising and lowering of the switch indicator 89, and therefore the valve stem 70, a cross-leg section 89a on one side of the switch indicator 89 is guided for movement within a guide rail 92 fixed inside the motor housing (Figure 11). To control the up and down movement of the valve stem 70, the switch indicator 89 has a thinner leg section 89b on one side opposite the guide indicator section 89a and is movable with the valve stem 70 between optical sensors 95a, 95b that control the electric motor 52 and limit the up and down movement of the switch indicator 89, and therefore the valve stem 70. The optical sensors 95a and 95b in this case are coupled to a circuit board 96 (Figure 10) that effects the operation of the electric motor 52, through an appropriate operator control, and the movement of the valve stem 70 between the sensors 95a, 95b. Adhering to an additional important aspect of the present embodiment, each control valve 15 operates such that the valve stem 70 closes and completely seals off communication between the main liquid inlet port 60 and the central flow passage 62 to the outlet port 65 to the spray section 12 before permitting communication from the outlet port 65 and the supply line 19 to the return or recovery port 66.As shown in Figures 4 and 7, when the electric motor 52 has rotated the output shaft 88 to raise the indicator switch 89 and the valve stem 70 coupled to it to an upper position with the indicator switch section 89b in contact with the upper optical sensor 95a, the O-ring 75 carried by the valve stem 70 is raised to an open position, allowing fluid communication from the main inlet port 60 of the control module to the central and cross passage sections 62, 65 and the outlet port 65 to the spray system 12. The lower E-pin 76 carries and supports the O-ring 75 in this raised or open position. Simultaneously, the lower end of the valve stem 70 is raised and placed in a closed position in the return or recovery port 66, with the annular seal 71 preventing the passage of fluid from the center passage 62 and the outlet port 60 to the return or recovery port 66. To prevent liquid communication to the outlet port 65 and the spray section 12, the electric motor 52 is operated in the reverse direction under the control for the circuit board 96, rotating the output shaft 88 in an opposite direction that lowers the optical switch indicator 89 and the valve stem 70 downward to an intermediate position that initially closes the liquid inlet port 60 while the recovery and return port 66 remains closed, as shown in Figure 8. In this intermediate position, it can be observed that the O-ring seal 75 is diverted to a position that closes the inlet port 60 while the lower valve stem 70 continues to close the recovery port 66.The continued operation of the drive motor 52 and the rotation of the output drive shaft 88 further lowers the valve stem 70 by a sufficient distance so that the O-ring 71 at the lower end of the valve stem 70 is positioned beyond the reduced-diameter return or recovery port 66. During this movement, the O-ring 75 remains deflected by the deflection spring 78 in its closed position, while the valve stem 70 and the E-pin 76 supporting the O-ring 75 continue to move downwards with the valve stem 70 (Figures 6 and 9).When the valve stem 70 and the optical switch indicator 89 are lowered to the level where the indicator section 89b contacts the lower optical sensor 95b, the lower end of the valve stem 70 and the O-ring 65 are positioned beyond the reduced-diameter return and outlet port 66, thus allowing communication of any downstream liquid to be drained back through the recovery outlet 66 to the return line 20. It will be appreciated that because the inlet port 60 is completely closed before the return or recovery port 66 is opened, there are no bursts or any other communication of liquid from the inlet port 60 to the return port 66 and the return line 15 during the liquid shutoff to the spray section 12, or any other appreciable loss of supply liquid that significantly affects the reliable monitoring of the liquid chemical or similar. To resume spraying, the drive motor 52 can be operated in reverse, raising the switch indicator 89 and valve stem 70 to a position that first closes the return or recovery port 66 while the O-ring 75 remains diverted in a position that closes the inlet port 60, and then, upon further raising of the valve stem 70, to the level at which the optical switch indicator section 89b engages the upper optical sensor 95a. This additional movement causes the E-pin 76 to lift the O-ring 75 and open the main liquid supply port 60, as shown in Figure 4, to supply liquid to the spray section 12. Based on the above, it can be observed that a valve-controlled spray system is provided that operates to shut off and turn on the liquid supply to the spray nozzles without unwanted liquid jets through the control valve that could affect the accurate monitoring of liquid chemical usage. The valve system uses a single valve stem that is controlled to completely shut off the liquid to the spray nozzles before allowing the liquid to drain into a return line of the spray system. It can also be observed that the valve control system is relatively simple in construction and operation, leading to economical manufacturing and reliable use.

Claims

1. A liquid spraying system, characterized in that it comprises: a liquid spraying section having at least one liquid spray nozzle; a liquid controller for controlling the flow of liquid from a liquid supply to said spraying section for discharge from at least said spray nozzle; said liquid controller including a liquid control valve having a valve body with a liquid supply port and a liquid recovery port; a first liquid supply line for directing liquid from said liquid supply to said liquid supply port; a second liquid supply line for directing liquid from said liquid supply port to said spraying section;a recovery line coupled to said recovery port for directing liquid in said second liquid supply line away from said spray section at the time of termination of the liquid supply to said spray section; said control valve having a valve stem;said control valve being operative to move said valve stem between (1) a first position that opens said liquid supply port to allow the direction of liquid from said first liquid supply line through said liquid supply port to said second liquid supply line and liquid spray section for discharge from at least one spray nozzle while blocking the flow of liquid through said recovery port to said recovery line, (2) a second position that blocks the supply of liquid from the first liquid supply line through said liquid supply port to said second liquid supply line while continuing to block the flow of liquid through said recovery port to said recovery line;and (3) to a third position wherein, during movement to said third position, said valve stem continues to block the flow of liquid from said first liquid supply line through said liquid supply port while said recovery port is opened to allow the remaining liquid in said second liquid supply line to flow back through said recovery port and recovery line such that the flow of liquid from said second liquid supply line to said liquid recovery line is only possible when said liquid supply port is closed.

2. The liquid spraying system according to claim 1, ivix / a / zuzz / ui uuu i characterized in that said valve stem extends through said liquid supply port and recovery port and in said first position allows liquid to flow from the liquid supply port to said second liquid supply line while simultaneously blocking flow through said recovery port, and in said second position simultaneously blocks liquid flow through said liquid supply port and recovery port, and upon movement of said valve stem to said third position, continues to block liquid flow through said supply port and then opens said recovery port to allow the remaining liquid in said second liquid supply line to flow to said recovery line.

3. The liquid spraying system according to claim 1, characterized in that said valve stem is threaded into said valve body for relative longitudinal movement, and including a motor coupled to said valve stem for selectively rotating said valve stem to move said valve stem between said first, second and third positions.

4. The liquid spraying system according to claim 3, characterized in that it includes a control for controlling the operation of said motor, said control including a switch carried by said valve stem for movement with said valve element between said first, second and third positions, and a pair of longitudinally separated sensors in said valve body coupleable by said switch for controlling the operation of said motor and limiting the movement of said valve stem between said first and said third positions.

5. The spraying system according to claim 1, characterized in that said valve stem carries a first sealing element for closing said liquid supply port when said valve stem is in said second and third positions and a second sealing element for closing said recovery port when said valve stem is in said first and second positions.

6. The spraying system according to claim 5, characterized in that said first sealing element is an annular sealing element mounted on said valve element and spring deflected for relative movement such that at the moment of movement of said valve stem from said first position to said second and third positions, said first sealing element closes said liquid supply port while allowing continuous movement of said valve stem to said second and third positions.

7. The spraying system according to claim 1, characterized in that said valve body has an elongated liquid flow passage communicating between said liquid supply port and said recovery port; said valve stem being mounted for reciprocating movement in said elongated flow passage between said first, second, and third positions; said second liquid supply line communicating with said elongated liquid passage at a location intermediate between said liquid supply port and recovery port; and said valve stem, when in said first position, permits liquid flow from said liquid supply port through said elongated liquid flow passage to said second liquid supply line while blocking liquid flow through said recovery port to said recovery line.and when in said second position it blocks the flow of liquid through said liquid supply port to said elongated liquid flow passage while simultaneously blocking the flow of liquid from said elongated flow passage through said recovery port, and as an incident to the movement to said third position it opens said recovery port to allow communication of liquid from said second liquid supply line and through said elongated passage and recovery port to said recovery line and while continuing to block the flow of liquid from said liquid supply through said liquid supply port to said elongated passage.

8. A liquid spraying system, characterized in that it comprises: a liquid spraying section having at least one liquid spray nozzle; a liquid controller for controlling the flow of liquid from a liquid supply to said spraying section for discharge from at least said spray nozzle; said liquid controller including a liquid control valve having a valve body with a liquid supply port, a liquid outlet port, and a liquid recovery port; a first liquid supply line for directing liquid from said liquid supply to said liquid supply port; a second liquid supply line for directing liquid from said liquid outlet port to said spraying section;a recovery line coupled to said recovery port for directing the liquid in said second liquid supply line away from said spray section at the time of termination of the liquid supply to said spray section; said control valve having a valve stem;said central valve being operative to move said valve stem between (1) a first position that opens said liquid supply port to allow the direction of liquid from said first liquid supply line through said liquid supply port and liquid outlet port to said second liquid supply line and liquid spray section for discharge from at least one spray nozzle while blocking the flow of liquid through said recovery port to said recovery line, (2) a second position that blocks the flow of liquid from said first liquid supply line through said liquid supply port and outlet port to said second liquid supply line while simultaneously blocking the flow of liquid through said recovery port to said recovery line;and (3) to a third position wherein during movement to said third position, said valve element continues to block the flow of liquid from said first liquid supply line through said liquid supply port and outlet port while said recovery port is opened to allow the remaining liquid in said second liquid supply line to flow back through said recovery port and recovery line such that the flow of liquid from said second liquid supply line to said liquid recovery line is only possible when said liquid supply port is closed.

9. The liquid spraying system according to claim 8, characterized in that said valve body has a liquid flow passage communicating between said liquid supply port and said recovery port; and said second liquid supply line communicates with said valve body liquid flow passage at a location between said liquid supply port and liquid recovery port.

10. The liquid spraying system according to claim 9, characterized in that said valve stem extends through said liquid flow passage of the valve body and said liquid supply port and recovery port and in said first position allows liquid flow from the liquid supply port to the liquid outlet port and a second liquid supply line while simultaneously blocking flow through said recovery port, and in said second position simultaneously blocks liquid flow through said liquid supply port and recovery port, and upon movement of said valve stem to said third position continues to block liquid flow through said supply port and then opens said recovery port to allow the remaining liquid in said second liquid supply line to flow into said recovery line.

11. The liquid spraying system according to claim 9, characterized in that said valve stem is threaded into said valve body for relative longitudinal movement, and including a motor coupled to said valve stem for selectively rotating said valve stem to move said valve stem between said first, second and third positions.

12. The spraying system according to claim 9, characterized in that said valve stem carries a first sealing element for closing said liquid supply port when said valve stem is in said second and third positions and a second sealing element for closing said recovery port when said valve stem is in said first and second positions.

13. The spraying system according to claim 912, characterized in that said first sealing element is mounted on said valve stem and the spring is deflected for relative movement so that at the moment of a movement of said valve stem from said first position to said second position, said first sealing element closes said liquid supply port while allowing continuous movement of said valve stem to said second and third positions.

14. The spraying system according to claim 13, characterized in that said valve stem carries a second annular sealing element longitudinally separated from said first sealing element which blocks the flow of liquid through said recovery port to said recovery line when said valve stem is in said first and second positions and at the moment of the movement of said valve stem to said third position, is carried by the valve stem to a position which opens said recovery port to allow the flow of liquid from said second liquid supply line through the liquid outlet port and the recovery port to said recovery line.

15. A liquid spraying system, characterized in that it comprises: a spray riser defining a liquid flow passage and supporting a plurality of spray nozzles, each having a discharge orifice in fluid communication with the liquid flow passage; a control valve for controlling the flow of liquid from a liquid supply to said liquid flow riser passage; said control valve having a valve body with a liquid supply port and a liquid recovery port; a first liquid supply line coupled to said supply port for directing liquid from said liquid supply to said liquid supply port; a second liquid supply line for directing liquid from said liquid supply port to said liquid flow passage of the spray riser;and a recovery line coupled to said recovery port to direct liquid in said second liquid supply line away from said sprinkler rise at the time of termination of the liquid supply to said sprinkler rise;said control valve having a valve element selectively movable between (1) a first position that opens said liquid supply port to permit the direction of liquid from said first liquid supply line through said liquid supply port to said second liquid supply line and liquid spray section for discharge from said plurality of spray nozzles while blocking the flow of liquid through said recovery port to said recovery line, (2) a second position that blocks the supply of liquid from the first liquid supply line through said liquid supply port to said second liquid supply line while continuing to block the flow of liquid through said recovery port to said recovery line;and (3) to a third position wherein, during movement to said third position, said valve element continues to block the flow of liquid from said first liquid supply line through said liquid supply port while said recovery port is opened to allow the remaining liquid in said second liquid supply line to return through said recovery port to said recovery line such that the flow of liquid from said second liquid supply line to said liquid recovery line is only possible when said liquid supply port is closed.

16. The liquid spraying system according to claim 15, characterized in that said valve body has a liquid flow passage communicating between said liquid supply port and said recovery port; and said second liquid supply line communicates with said valve body liquid flow passage at a location between said liquid supply port and liquid recovery port.

17. The liquid spraying system according to claim 1, characterized in that said valve element is an elongated valve stem extending through said liquid supply port and recovery port and, in said first position, permits the flow of liquid from the liquid supply port to said second liquid supply line while simultaneously blocking the flow through said recovery port, and in said second position simultaneously blocks the flow of liquid through said liquid supply port and recovery port, and upon movement of said valve stem to said third position, continues to block the flow of liquid through said supply port and then opens said recovery port to permit remaining liquid in said second liquid supply line to flow into said recovery line.

18. The liquid spraying system according to claim 17, characterized in that said valve stem is threaded into said valve body for relative longitudinal movement, and including a motor coupled to said valve stem for selectively rotating said valve stem to move said valve stem between said first, second, and third positions. IVIA / a / ZUZZ / UI UUU I 19. The liquid spraying system according to claim 17, characterized in that said first sealing element is mounted on said valve stem and the spring is deflected for relative movement so that at the moment of the movement of said valve stem from said first position to said second position, said first sealing element closes said liquid supply port while allowing the continued movement of said valve stem to said second and third positions.

20. The liquid spraying system according to claim 18, characterized in that said valve stem carries a second annular sealing element longitudinally separated from said first sealing element which blocks the flow of liquid through said recovery port to said recovery line when said valve stem is in said first and second positions and, at the moment of the movement of said valve stem to said third position, is brought by the valve stem to a position which opens said recovery port to allow the flow of liquid from said second liquid supply line through the liquid outlet port and the recovery port to said recovery line.

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