IL145356A

IL145356A - Automatic nutrient supplying system with inflowing air intercepting device

Info

Publication number: IL145356A
Application number: IL145356A
Authority: IL
Original assignee: Choi Hyung In; Handelsonderneming Revaho B V
Priority date: 1999-02-04
Filing date: 2001-09-10
Publication date: 2007-10-31
Also published as: WO2000052994A2; AU3666300A; WO2000052994A3; IL145356A0; HK1043914A1; EP1175143A2; EP1175143A4

Description

145356/2 Ί ΊΝ nt»3D 1Ό>#? O ΓΟΐΓ) D £)t?N JWEIVTIN TDiyE Automatic Nutrient Supplying System with Inflowing Air Intercepting Device Choi HYUNG-IN and HANDEL SONDERNEMING REVAHO B.V. c:093/02430 AUTOMATIC NUTRIENT SUPPLYING SYSTEM WITH INFLOWING AIR INTERCEPTING DEVICE Technical Field The present invention relates, in general, to a-nutrient supplying system used for automatically and controllably supplying a nutrient, such as water or water mixed with a fertilizer, to a variety of plants, such as vegetables, fruits, flowers, etc., and, more particularly, to an automatic nutrient supplying system provided with an inflowing air intercepting device, the device being designed to prevent atmospheric air from undes rably flowing into a liquid-fertilizer pipe when a liquid-fertilizer tank is empty .^during a' nutrient supplying operation of the system, the device thus preventing a pump from being damaged and preventing the system from malfunctioning during a nutrient supplying operation.

Background Art As well known to tho.se skilled in the art, . an automatic nutrient supplying system, designed to controllably supply a nutrient, such as waters..' or wa.ter mixed with a fertilizer, to plants, such as vegetables, fruits, flowers, etc, has been proposed and used on farms. Such a system has a controller, and so it controls the amount of nutrient and the nutrient supplying interval in accordance with both the amount of solar radiation and the draining condition of soil.

Fig. la is a circuit diagram of' a conventional automatic nutrient supplying system provided with both a magnet p mp and a two-way valve in accordance with an embodiment of the prior art. As shown in the drawing, this system comprises a water tank 10. A main pump 60 is connected to the water tank 10 through a feed pipe 15 and pumps water from the tank 10 so as to supply a nutrient, or water mixed with a fertilizer, to a filter 70. The filter 70, connected to the pump 60 through a nutrient pipe 65, filters the nutrient from the pump 60 prior to supplying 'the nutrient to plants. . A liquid-fertilizer tank 30 is connected to the feed pipe 15 through a fertilizer pipe 31, with both a magnet pump 34 and a two-way valve 36 being mounted to the pipe 31. The magnet pump 34 pumps the liquid-fertilizer from the tank 30 r thus supplying the liquid fertilizer to the feed pipe 15 · through the fertilizer pipe 31. The two-way valve 36 is positioned between the feed pipe 15 and the magnet pump 34 and is used for controlling the flow of liquid fertilizer within the pipe 31 at predetermined time intervals under the control of a controller.

However, the above system is problematic in that atmospheric air may undesirably flow, into the fertilizer pipe 31 when the liquid-fertilizer tank 30 is empty during a nutrient supplying-'-operation of the system, thus damaging the magnet pump 34 and allowing the system to malfunction. In addition, both the main pump SO and the magnet pump 34 are designed to be continuously operated during an operation o the system. Therefore, when high pressure, caused by the operation of the magnet pump 34, is applied to the two-way valve 3S with the valve 36 being closed under the control of the controller, the valve 36 is undesirabl " --vibrated due to the high pressure. In such a case, the two-way valve J6 fails to be . stably operated.

Another problem experienced in the above system resides in that it is necessarily provided with the magnet pump 34 for pumping "'the liquid fertilizer from the liquid-fertilizer tank 30, thus being increased in the production cost.

In an effort to overcome the problems experienced in the system using the two-way valve, another supplying system of Fig. lb has been proposed.

As shown in Fig. lb, this system uses a magnet pump and a three-way valve. In the same manner as than described for the system of Fig. la, the system of Fig. lb comprises a water tank 10, a main pump 60 connected to the water tank 10 through a feed pipe 15, and a filter 70 connected to the pump 60 through a nutrient pipe 65. A liquid-fertilizer tank 30 is connected to the feed pipe 3/02430 -3- 15 through a fertiliser pipe 31, with both a magnet pump 34 and a three-way valve. 38 being mounted to the pipe 31. The magnet pump 34 pumps the liquid-fertilizer from rhe tank 30, thus supplying the liquid fertilizer to the feed pips 15 through the fertilizer pipe 31. The three-way valve 36 in place of the two-way valve. 36 of Pig. la is ·> positioned between the feed pipe 15 and the magnet pump 34. The above three-way valve 38 is also connected to the fertilizer pipe 31 at a position- between the liquid-fertilizer tank 30 and the magnet pump 34 through a bypass pipe 35.

When the three-way valve 38, used for controlling the flow of liquid fertilizer, from the magnet pump 34 to the feed pipe 15 under the control of the controller, is closed in an operation .of the above system, the liquid fertilizer from the -tank 30 continuously circulates within the system through the bypass pipe 35. Therefore, the system of Fig. lb somewhat effectively overcomes the problem experienced in the system of Fig. la. That is, this system having the three-way valve is free from an unstable operation of the valve different from the system having the two-way valve.

However, the system of Fig. lb is problematic in that it is necessarily provided with the magnet pump 34, thus being increased in the production cost in the same manner as the system of Fig. la. Another problem experienced in the system resides in that atmospheric ai may undesirably flow into the fertilizer pipe 31 when the iquid-fertili2er tank 30 is empty during a nutrient supplying operation of the system, thus damaging the magnet pump 34 and allowing the system to malfunction.

In order to solve the problem of an increase in the production cost of the system and of damage to the pump of the system, Korean jvio . I °1°1°Ι - o o M s-3-2? ¾ proposes an automatic nutrient supplying system. As shown in Figs. 2a and 2b, the above Korean system comprises a water tank 10, A main pump SO is connected to the water tank 10 through a feed pipe 15 and pumps water 'from the tank 10 so as to supply a nutrient, or water mixed with a fertilizer, to a filter 70. The system also has a plurality of liquid-fertilizer tanks 30, which are connected to the feed pipe 15 through their fertilizer outlet pipes 82. , A liquid-fertilizer level maintaining unit 80 is connected to each of the fertilizer tanks 3D through a fertilizer inlet pipe 81. The units 80 receive the liquid fertilizer from the liquid-fertilizer tanks 30 > and maintain a desired level of the liquid fertilizer when the liquid fertilizer is fed from the tanks 30 to the feed pipe 15 in response to the -suction force of the main pump 60. The filter 70, connected to "the pump 60 through a nutrient pipe 65, filters the nutrient from the pump 60 prior to supplying the nutrient to plants.

In an operation of the above system, the liquid-fertilizer level maintaining units -80 maintain a desired level of the, liquid fertilizer, which is fed from the tanks 30 through the fertilizer inlet pipes 81. The liquid-fertilizer level maintaining units 80 also allow a predetermined amount of liquid fertilizer to be supplied to the feed pipe 15 through the fertilizer outlet pipes 82. When a liquid-fertilizer tank 30 is empty during an operation of the system, the port 83 of the fertilizer outlet pipe 82 is closed by a ball valve 87, Therefore, this system is free from a liquid-fertilizer pump, thus solving the problem of an increase in the production cost of the system and of damage to such a liquid-fertilizer pump .

However, this system is problematic in that it fails to -completely prevent atmospheric air from undesirably flowing into the fertilizer pipe when a liquid-f rtilizer tank 30 is empty during a nutrient supplying operation of the system.

Disclosure of the Invention Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide an automatic nutrient supplying system, which is provided with an inflowing air intercepting device for almost completely preventing atmospheric air from undesirably -s-flowing into a liquid fertilizer pipe when a liquid-fertilizer tank is empty during a nutrient supplying operation of the · system, and is provided with a valve means for controlling the flow of liquid fertilizer within the fertilizer pipe and removing negative pressure from the pipe, thus effectively preventing atmospheric air from undesirably flowing into the pipe, and which effectively supplies warer to plants even when atmospheric air flows into the pipe, and which performs its desired operation when new liquid fertilizer is being refilled into the empty tank.

In order to accomplish the above object, the present invention provides an automatic nutrient supplying system, comprising: a water tank and a liquid-fertilizer tank; a main pump connected to the water tank through a feed- pipe and used for pumping water from the tank; a filter connected to the main pump through a nutrient pipe and used for filtering a nutrient fed from the main pump prior to supplying the nutrient to plants; an inflowing air intercepting device connected to a bottom wall of the fertilizer tank at its fertilizer inlet port formed on its top wall through a first fertilizer pipe and connected to the feed pipe at its fertilizer outlet' port formed on its bottom wall, the device having a cylindrical shape and being provided with a float -ball therein, the float-ball being movable within the device in a vertical direction in accordance with a level of a fertilizer within the device so as to selectively close the fertilizer outlet portr the device thus preventing atmospheric air from flowing from the first fertilizer pipe into the system when the liquid-fertilizer tank is empty during a nutrient supplying operation of the system; and a valve means used for controlling the flow of the fertilizer within the system and removing negative pressure from the system, the valve means being connected to the fertilizer outlet port of the device at its first inlet part through a second fertilizer pipe, the valve means being also connected to the 'first fertilizer pipe at its second inlet part through an air .pipe and being connected to the feed pipe at its outlet' part through a third fertilizer pipe, the valve having a fertilizer passage extending from the first inlet part to the outlet part and an air passage extending from the second inlet part to the outlet part, the fertilizer passage and the air passage being periodically and alternately closed under the control of a controller in a way such that the fertilizer passage is opened when the air passage is closed ► Brief Description of the Drawings The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in vhich: Fig. la is a circuit diagram of a conventional automatic nutrient supplying system . provided with both a magnet pump and a two-way valve in accordance with an embodiment of the prior art; Fig. lb is a circuit diagram of a conventional automatic nutrient supplying system provided with both a magnet pump and a three-way valve in accordance with another embodiment of the prior art; Fig. 2a is a perspective view of a conventional automatic nutrient supplying system in accordance with a further embodiment of the prior art; Fig. 2b is a perspective view of a liquid-fertilizer level maintaining unit included in the nutrient supplying system of Fig. 2a; Fig. 3 is a perspective view of an automatic nutrient supplying system in accordance with the primary embodiment of the present invention; Fig. 4 is a sectional view, showing the operation of the system of Fig, 3; Fig. 5 is a sectional view, showing the operation of an automatic nutrient supplying system in accordance with the second embodiment: of the present invention; Figs. 6a and 6b are sectional views, respectively showing the operation of automatic nutrient supplying systems in accordance with the third and fourth embodimenrs of the present invention; and Figs. 7a and 7b are seotional views, respectively showing the operation of automatic nutrient supplying systems in accordance with the fifth and sixth embodiments of the present invention.

Best Mode for Carrying Out the Invention Fig. 3 is a perspective vieV of an. automatic nutrient supplying system in accordance with the primary embodiment of the present invention. Fig. 4 is a sectional view,, showing the operation of the system of Fig. 3. As shown in Figs. 3 and 4, the system of this invention comprises a water tank 10, A main pump 60 is connected to the water tank 10 through 'a feed pipe. 15 and pumps water from the tank 10 so as to supply a nutrient, or water mixed with a fertilizer, to a filter 70, The filter 70 is connected to the pump 60 through a nutrient pipe 65 and filters the nutrient from the pump SO prior to supplying the nutrient to plants.

An automatic water supply pump (not shown) , having a conventional water level sensor, is installed within the water tank 10 and allows the tank 10 to be normally filled with water to a predetermined level.

The feed pipe 15, having a predetermined diameter, extends from the bottom c: the water tank 10 to the main pump SO. The pump 60 is connected to the filter 70 through the nutrient pipe 65.

Water under pressure flows from the tanks 10 through the feed pipe 15 by the suction force of the pump 50 and passes through the filter 70 while being filtered.

Both an inflowing air intercepting device 40 and a valve means 50 are mounted to a pipe extending from each liquid-fertilizer tank 30 to the feed pipe 15. The inflowing air intercepting device 40 receives liquid fertilizer from an associated liquid-fertilizer tank 30 and maintains a desired level of the liquid fertilizer when the liquid fertilizer is fed from the tank 30 to the feed pipe 15 in response to the suction force of the main pump 60. The above device 40 also prevents atmospheric air from undesirably flowing into the second fertilizer pipe when an associated liquid-fertilizer tank 30 is empty during a nutrient' supplying operation 0% the system. The valve means 50 controls the flow of the liquid fertilizer flowing from the device 40.

In the preferred embodiment of the drawings, the" system has three liquid-fertilizer tanks 30, three inflowing air intercepting devices 40 and three valve means 50. However, it should be understood that the .number of tanks 30, devices 40 and valve means 50 may be changed as desired.

A first fertilizer pipe 31a extends from the bottom of each fertilizer tank 30 at its upper end and is connected to the fertilizer inlet port 41, formed on the top wall of an associated device 40, at its lower end.

The inflowing air intercepting device 40 has a cylindrical housing suitable for receiving a predetermined amount of liquid fertilizer fed from the liquid-fertilizer tank 30. The above device 40 has a float-ball 45, which floats on the water surface within the housing of the device 40 so as to selectively close the liqui d-fertilizer outlet port 49 formed on the bottom of the housing.

A second fertilizer pipe 31b extends downwardly from the outleL port 49 of the device 40 and is bent at a 5 right angle prior to being connected to a first inlet part 51 of an associated valve means 50.

In the primary embodiment of this invention, each valve means 50 is a conventional, three-way valve having two inlet ports and one outlet port as shown in Fig. 4. D The valve means 50 also has the first inlet part · 51 at one end thereof and is connected to the second fertilizer pipe 31b at the part 51. The above valve means 50 further has an outlet part 59 at the other end thereof. The outlet part 59 communicates with a fertilizer passage 5 54 of the valve means 50 and is connected to the feed pipe 15 through a third fertilizer pipe 31c. A second inlet part 52 is provided at the rear portion of the valve means 50 and is connected to an air pipe 31d.

In this embodiment, the air pipe 31d is connected to 0 the second inlet part 52 of the valve means 50 at one end thereof and is connected to the first fertilizer pipe 31a at the other end thereof.

In the above valve means 50, an actuator 55 is moved in opposite directions by a solenoid (not shown) so as to selectively open the fertilizer passage 54 or the air passage 56 of the valve means 50.

That is, when the actuator 55 moves forward to push a packing 53, the packing 53 closes the fertilizer passage 54 while opening the air passage 56. On the other hand, when the actuator 55 moves backward to release the packing 53, the packing 53 opens the fertilizer passage 54 while closing the air passage 55.

In such a case, the above actuatqr 55 is operated within the valve means 50 under the control of a controller (not shown) , thus being precisely operated at a predetermined time interval. For example, the actuator 55 may be repeatedly operated with one cycle of five seconds, wherein the actuator 55 opens the fertilizer passage 54 while closing the air passage 56 for an initial 2.5 seconds and opens the air passage 56 while closing the fertilizer passage 54 for the remaining 2.5 seconds .

The above valve means 50 is operated in conjunction with the main pump 60 and may be controlled in -its passage controlling interval by the controller in accordance with a plant, liquid fertilizer and a plant growing condition.

The system of this primary embodiment will be operated as follows.

When the system starts its nutrient supplying operation with a desired amount of liquid fertilizer filled in each of the fertilizer tanks 30, water flows from the water tank 10 into the feed pipe 15 by the suction force of the main pump 60.

On the other hand, the liquid fertilizer is fed from the fertilizer tanks 30 .into the devices 40 through the first fertilizer pipes 31a as shown by the solid arrows of Fig. 4. When the liquid fertilizer reaches a predetermined level within each of the, tanks 3Q, the float-ball 45 is raised to open the fertilizer outlet port 49 of the device 40, thus allowing the fertilizer to be fed into the second fertilizer pipe 31b through the port 49.

When the actuator 55 moves backward within each valve means 50 under the control of the controller (not show) , the actuator 55 releases the packing 53. In such a case, the packing 53 opens the fertilize passage 54 while closing the air passage 56 for a time, for example, 2.5 seconds. Therefore, the liquid fertilizer from the second fertilizer pipe 31b passes through the first inlet part 51 and the fertilizer passage 54 prior to flowing into the third fertilizer pipe 31c through the outlet part 59. -The liquid fertilizer thus reaches the feed pipe 15.

After the liquid fertilizer is supplied for 2.5 seconds, the actuator 55 moves forward within each valve means 50 under the control of the controller, and so the actuator 55 opens the second inlet part 52 while closing the fertilizer passage 54. In such a case, the supply of liquid fertilizer is temporarily stopped. After a predetermined time, for example, 2.5 seconds, from the forward movement of the actuator 55, the actuator 55 moves backward to release the packing 53, thus opening the fertilizer passage 54 while eiosing the air passage 56. Therefore, the liquid fertilizer is fed from · the tanks 30 to the feed pipe 15. Such a cycle is repeated for an operation of the system, thus effectively supplying nutrients to the plants.

When a liquid-fertilizer tank 30 is empty during the operation of the system, the liquid fertilizer of an associated device 40 is drained into the feed pipe 15, thus allowing the float-ball 45 to be moved downwardly within the housing of the device 40. Therefore, the float-ball 45 closes the fertilizer outlet port 49 of the device 40 and prevents atmospheric air from being introduced into the second fertilizer pipe 31b.

In such a case, negative pressure is formed within the second fertilizer pipe 31b.

When the actuator 55 moves forward within the valve means 50 after 2.5 seconds, the actuator 55 opens the air passage 56 while closing the fertilizer passage 54, thus allowing air to be introduced from the first fertilizer pipe 31a into the second fertilizer pipe 31b through the air pipe 31d as shown by the dotted arrows of Fig. 4. The second fertilizer pipe 31b is thus free from negative pressure.' After 2.5 seconds from the forward movement of the actuator 55, the actuator 55 moves backward to release the packing 53, thus opening the fertilizer passage 54 while closing the air passage 56. Therefore, the float-ball 45 closes the port 49 of the device 40, thus preventing atmospheric air from being introduced into the second fertilizer pipe 31b.

Thereafter, negative pressure is formed again within the second fertilizer pipe 31b prior to being removed from the pipe 31b as .-described above. Such an inflowing air intercepting operation is repeated during the operation of the system.

When new liquid fertilizer is being refilled into the empty tank 30, the fertilizer is introduced into the device 40 through the first fertilizer pipe 31a. When the fertilizer completely reaches a predetermined . level within the housing of the device 40, negative pressure acting on rhe float-ball 45 is removed, th s allowing the ball 45 to be raised within the device 40. In such a case, the liquid fertilizer flows into the second fertilizer pipe 31b through the port 49 and normally flows into the feed pipe 15 under the control of the valve means 50.

The system of this embodiment effectively prevents atmospheric air from undesirably flowing into the second fertilizer pipe when a liquid-fertilizer tank is empty during a nutrient supplying operation of the system. This system also normally performs its desired operation when new liquid fertilizer is being refilled into the empty tank.

Fig. 5 is a sectional view, showing the operation of an automatic nutrient supplying system in accordance with the second embodiment of the present invention. As shown in the drawing, the general shape of the system of this embodiment remains the same as that described for the primary embodiment', but two valves 91 and 92 are provided for each device 40 of the system. That is, a first two-way valve 91 is ' mounted to the junction between the second and third fertilizer pipes 31b and 31c* The above first valve 91 is activated and inactivated at a predetermined time interval, for example, 2.5 seconds, under the control of a controller to open and close its fertilizer passage 94. air pipe 31d extends between the first and second fertilizer pipes 31a and 31b, with a second two-way valve 92 being mounted to the air pipe 31d. The above second valve 92 is activated and inactivated at a predetermined time interval under the control of the controller to close and open the air pipe 31d.

The system of the .second embodiment will be operated as follows.

When the system starts its nutrient supplying operation with a desired amount of liquid fertilizer filled in each of the fertilizer tanks 30, water flows from the water tank 10 into the feed pipe 15 by the suction force of the- main pump 60. On the other hand, the liquid fertilizer is fed from the fertilizer tanks 30 into the inflowing air "intercepting devices 40 through the first fertilizer pipes 31a as shown by t e solid arrows of Fig. 5. When the liquid fertilizer reaches a predetermined level within each of the tanks 30, the float-ball 45 is raised to open the fertilizer outlet port 49 of the device 40, thus allowing the fertilizer to be fed into the second fertilizer pipe 31b through the port 49.

When the actuator 95 of the first two-way valve 91 moves backward under the control of a controller (not show) , the actuator 95 releases the packing, thus opening the fertilizer passage 94 for a time, for example, 2.5 seconds. On the other hand, the actuator 95 of the second two-way valve 92 moves forward under the control of the controller, thus closing the air passage 96 of the valve 92 for the same time. In such a case, the Liquid fertilizer from the second fertilizer pipe 31b passes through the fertilizer passage 94 prior to flowing into the third fertilizer pipe 31c. The liquid fertilizer thus reaches the feed pipe 15.

After the liquid fertilizer is supplied for 2.5 seconds, the actuator 95 of the first valve 91 moves forward, while the actuator 95 of the second valve 92 moves backward. Therefore, the fertilizer passage 94 of the first valve 91 is closed, while the air passage 96 of the second valve 92 is opened. In such a case, the supply of liquid fertilizer is temporarily stopped. After a predetermined time, for example, 2,5 seconds, from the forward movement of the actuator 95 of the first valve 91, this actuator 95 moves backward to open the fertilizer passage 94. In such a case, the actuator 95 of the second valve 91 moves ' forward to close the air passage 96.· Therefore, the liquid fertilizer is fed from the tanks 30 to the feed pipe 15. Such a cycle is repeated for an operation of the system, thus effectively supplying nutrients to the plants.

When a liquid-fertilizer tank 30 is empty during the operation of the system, the liquid fertilizer of an associated device 40 is drained into the. feed pipe 15, thus allowing the float-ball 45 to be ' moved downwardly within the housing of the device 40. Therefore, .the float-ball 45 closes the fertrlizer outlet port 49 of the device 40 and prevents atmospheric air from being introduced into the second fertiliser pipe 31b.

When the actuator 95 of the first valve 91 moves forward after 2.5 seconds, thus closing the fertilizer passage 94 for a time, for example, 2.5 seconds, the actuator 95 of the second valve 92 moves backward, thus opening the air passage 96, Therefore, air is allowed to be introduced from the first fertilizer pipe 31a into the second fertilizer pipe 31b through the: air pipe 31d as shown by the dotted arrows of Fig. 5. The second fertilizer pipe 31b is thus free from negative pressure.

After 2.5 seconds from the forward movement of the actuator 95 of the first valve 91, this actuator 95 moves backward to open the fertilizer passage 94. In such a case, the actuator 95 of the second valve 92 moves forward to close the air passage 96. Therefore, the float-ball 45 closes the port 49 of the device 40, thus preventing atmospheric air from being introduced into the second fertilizer p e 31b.

Thereafter, negative pressure is formed again within the second fertilizer pipe 31b prior to being removed from the pipe 31b as described above.. This inflowing air intercepting operation is repeated during the operation of the system.

When new liquid fertilizer is being refilled into the empty tank 30, the fertilizer is introduced into the device 40 through the first fertilizer pipe 31a. When the fertilizer completely reaches a predetermined level within -the housing of the device 40, negative pressure acting on the float-ball 45 is removed, thus allowing the ball 45 to be raised within the device 40. In such a case, the liquid fertilizer flows into the second fertilizer pipe 31b through the port 49 and normally flows into the feed pipe 15 under the control of the first valve 91.

The system of this embodiment, having the two valves 91 and 92, effectively prevents atmospheric air from undesirably flowing into the "second fertilizer pipe 31b when a liquid-fertilizer tank is empty during a nutrient supplying operation of the system. This system also normally performs its desired operation when new liquid fertiliser is being refilled into the empty tank.

Figs. 6a and 6b are sectional views, respectively showing the operation of automatic nutrient supplying systems in accordance with the third and fourth embodiments of the present invention. In the third embodiment, the general shape of the system remains the same as that described for the primary embodiment, but each air pipe 31d, connected to a valve means 50 at its first end, extends to a height higher than an associated fertilizer tank 30 and is opened to the atmosphere at its second end. In the fourth embodiment, the general shape of the system remains the same as that described for rhe second embodiment, but each air pipe 31d,' connected to a second two-way valve 92 at its first end, extends to a height higher than an associated fertilizer tank 30 and is opened to the .atmosphere at its second end.

In each of the systems of Figs. Sa and 6b, negative pressure 'is removed from the second fertilizer pipe 31b by atmospheric air directly introduced into the pipe 31b from the open end of the air pipe 31d different from the embodiments of Figs. 4 and 5, wherein negative pressure is removed from the second fertilizer pipe 31b by air introduced into the* pipe 31b from the first fertilizer pipe 31a.

In each of the systems of Figs. 6a and 6b it is not necessary to connect the second end of the air pipe 31d to the .first fertilizer pipe 31a, thus reducing the number of parts of the systems. In addition, the system is completely free from a fertilizer leakage at the junction between the first fertilizer pipe 31a nd the air pipe 31. Another advantage of the systems of Figs. 6a and 6b resides in that it is possible to simplify the process of producing the systems, thus improving the productivity while producing the systems.

Figs. 7a and 7b are sectional views, respectively showing the operation of automatic nutrient supplying systems in accordance with the fifth and sixth embodiments of the present invention.

In the fifth embodiment, the general shape of the system remains the same as that described for the third embodiment of Fig. 6a, but a manual valve 99· is mounted to the air pipe 31d so as to allow a user to control the flow of air within the pipe ,31d. The above air pipe 31d is connected to the valve means 50 at its first end and extends upwardly prior to being opened to the atmosphere at its .second end, In the sixth embodiment, the general shape of the system remains the same as that described for the fifth embodiment of Fig. 7a, but the air pipe 31d having the manual valve 99 is connected to the second fertilizer pipe 31b at its first end and extends upwardly prior to being opened . to the atmosphere at its second end.

In. the operation of each of the systems of Figs. 7a and 7b, the liquid fertilizer is normally fed from the fertilizer tank 30 into the feed pipe 15 through the valve 50, 91, with the manual valve 99 closing the air pipe 31d When a liquid-fertili2er tank 30 is empty during a nutrient supplying operation of the systems, the float- ball 45 closes the fertilizer outlet port 49 of the device 40 and allows negative pressure to be 'formed within the second fertilizer pipe 31b. In such a case, new liquid fertilizer is being refilled into the empty tank 30 by a user who also opens the manual valve 99 of the air pipe 31d. The negative pressure is thus removed from the second fertilizer pipe 31b. Thereafter, the manual valve 99 is closed. The float-ball 45 is ·· raised within the device 40, thus opening the fertilizer outlet port 49 of the device 40 and allowing the fertilizer to be fed into the second .fertilizer pipe 31b through the port 49.

Industrial Applicability As described above, the present invention provides ■ an automatic nutrient supplying system. This system is provided with an inflowing air intercepting device for almost completely preventing atmospheric air from undesirably flowing into a fertilizer pipe when a liquid- fertilizer tank is empty during a nutrient supplying operation of the system. This system is also provided with a valve means for controlling the flow of liquid fertilizer within the fertilizer pipe and removing negative pressure from the pipe. The system thus effectively prevents atmospheric air from undesirably flowing into the fertilizer pipe, and effectively supplies water to plants eve when atmospheric air flows into the pipe. The system normally performs its desired operation when new liquid fertilizer is being refilled into the empty tank. The system is thus free from malfunctioning during a nutrient supplying operation and is free from damage to a pump.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

1. An automatic nutrient supplying system, comprising: a water tank and a liquid-fertilizer tarik; - - a ma^n pump ^connected to said water tank through a feed pipe and used for pumping water from the tank; a filter ""'connected to said main pump through a nutrient pipe and used for filtering, a nutrient fed from the main pump prior to supplying the nutr^nt to plants; an inflowing air intercepting device1 connected to a bottom wall of said fertilizer tank at its fertilizer inlet port formed on its top wall through a first fertilizer pipe and connected 'to said feed pipe at its fertilizer outlet port' formed on its bottom wall, said device having a cylindrical shape and being provided with a loat-ball therein, said float-ball being movable within the device in a vertical direction in accordance with a level of a fertilizer within the device so as to selectively close said fertilizer outlet port, said device thus preventing atmospheric air from flowing from the first fertilizer pipe into the system when the liquid-, fertilizer tank is -empty during a. nutrient supplying operati n of the,, system; and valve means1) used for controlling the flow of the fertilizer within the system and removing negative pressure from the system.

2. The system according to claim 1, wherein said valve means comprises a two-way valve connected to the fertilizer outlet port of said inflowing air intercepting device at its first inlet part .through a second fertilizer pipe, said valve being also connected to said first fertilizer pipe at its second inlet part through an air pipe and being connected to said feed pipe at its outlet part through a third fertilizer pipe, said valve having a fertilizer passage extending from the first inlet part to the outlet part and an air passage extending from the second inlet part to the outlet part, said fertilizer passage and said air passage being periodically and alternately closed under the control of a controller in a way such that the fertilizer passage is opened when the air passage is closed.

3. The system according to claim 1, wherein said valve means comprises : a first two-way valve having a fertilizer passage and mounted to a junction between second and third fertilizer pipes respectively connected to said inflowing air intercepting device and said feed pipe, said first valve being activated and inactivated at a predetermined time interval under the control of a controller to open and close said fertilizer passage, with an air pipe extending between the first and second fertilizer pipes; and a second two-way valve mounted to said air pipe, said second valve being activated and inactivated at the predetermined time interval under the control of the controller to close .and open the air pipe.

4. The system according to claim 2 o¾ 3, wherein said air pipe extends to a height higher than said fertilizer tank and is opened to the atmosphere at its end positioned higher than the fertilizer tank.

5. The system according to claim 4, wherein a manual valve is mounted to said air pipe so as to allow a user to control the flow of air within the pipe. For the Applicants, Fenster & Co. Patent Attorneys, Ltd. c:093/02430