Liquid sagging prevention mechanism of two-fluid spray device

Abstract

To provide a liquid sagging prevention mechanism of a two-fluid spray device which prevents liquid sagging in residual water, shortens a time to stop of spray, reduces the influence of a height of installation of a first non-return valve or the influence of an external environment such as air biting, and enhances robust property.SOLUTION: A bypass pipe 22 is provided which connects a first air supply pipe 14 and a secondary side of a first non-return valve 5 of a second water supply pipe 6 through a second non-return valve 21, supplies air to the second water supply pipe from the first air supply pipe only when a primary side pressure of the second non-return valve is higher than a secondary side pressure thereof, and discharges water in the second water supply pipe and a two-fluid nozzle 1. The first non-return valve has a predetermined cracking pressure larger than a difference between a residual pressure on the primary side of the first non-return valve 5 and an atmospheric pressure. When water supply is stopped, a pressure difference between the primary side of the first non-return valve and the secondary side thereof is less than the cracking pressure, water does not flow and spray is stopped, the pressure on the primary side of the second non-return valve becomes higher than the pressure on the secondary side thereof, and water in the second water supply pipe and the nozzle is discharged by air supply.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a drip prevention mechanism for a two-fluid spray device that sprays gas and liquid in the form of mist. [Background technology]

[0002] Traditionally, in factories, humidification has been achieved by spraying extremely fine mist of fine particles with a Sauter mean diameter of approximately 10 μm from a two-fluid mist nozzle of gas and liquid. This makes it difficult for static electricity to be generated, preventing a decline in manufacturing quality or a worsening of product defect rates due to the attachment of foreign matter or incorrect operation of equipment. For example, in the component mounting process, it is possible to prevent problems caused by static electricity, such as electrostatic damage to components or poor mounting of boards, and it is also expected to improve the comfort of the work space and reduce the load on air conditioning due to the cooling effect of the heat of vaporization. In this way, mist spraying from a two-fluid mist nozzle does not require a large boiler, and can perform localized humidification while keeping running costs low, so its introduction is expected to reduce CO2 emissions. 2 This is also welcomed from the perspective of cost reduction.

[0003] 5A, such a spray device using a two-fluid mist nozzle has a main water pipe 104 connected to a water supply source 102 via an on-off water control valve 103, and a mist nozzle 101 connected to the downstream end of multiple water branch pipes 106 whose upstream ends are connected to the main water pipe 104. Also, a main air pipe 114 is connected to an air supply source 112 via an on-off air control valve 113, and the mist nozzle 101 is connected to the downstream end of multiple air branch pipes 116 whose upstream ends are connected to the main air pipe 114. The control panel opens and closes each of the control valves 103, 113 based on the humidity detected by the humidity sensor to control the mist spray.

[0004] In such a spray device, when mist spray is stopped for some reason, liquid drips from the tip of the mist nozzle 101.

[0005] To prevent this, a push-out method has been proposed in which a bypass path 122 is provided that can supply air from the main air pipe 114 to the water branch pipe 106 via an on-off valve 121, and the water in the water branch pipe 106 is pushed out by air through the bypass path 122 to blow it away, thereby preventing dripping from the nozzle 101 (Patent Document 1).

[0006] However, in a large factory, for example, all the water in the water branch pipe 106, which is about 50 m long, is drained, so it takes a long time to stop spraying. In addition, spraying begins after the water branch pipe 106 is filled with water, so the time it takes to start spraying is also long.

[0007] To solve this problem, a method for releasing residual pressure, as shown in Figure 5B, is known in which when spraying stops, drain valve 130 connected to main water pipe 104 is opened to reduce the water pressure in main water pipe 104 and release the residual pressure, and water pressure in branch water pipe 106 is reduced to keep the water pressure upstream of mist nozzle 101 lower than atmospheric pressure, thereby preventing water from flowing into nozzle 101 and preventing dripping. Note that check valve 125 in branch water pipe 106 has the function of preventing air from flowing back from nozzle 101 and maintaining negative pressure. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent application No. 2022-556972 Summary of the Invention [Problem to be solved by the invention]

[0009] However, such a device has problems such as being easily affected by the liquid piping path, being affected by the air layer in the liquid piping path, and causing dripping (water dripping from the tip of the nozzle). In other words, unless the water pressure on the upstream side of the nozzle is controlled to be equal to or lower than atmospheric pressure while taking into consideration the effect of the head difference due to the vertical length of the liquid piping, or the effect of the air layer in the liquid piping path (i.e., air entrapment), or both of these effects, there is a problem of dripping.

[0010] Therefore, the object of the present invention is to solve the above problems by providing a drip prevention mechanism for a two-fluid spray device that is less susceptible to the influence of the liquid piping path and the air layer in the liquid piping path and does not cause dripping, in other words, does not cause dripping due to residual water, shortens the time until spraying stops, is less affected by the installation height of the first check valve or the influence of external environments such as air entrapment, and is highly robust. [Means for solving the problem]

[0011] In order to achieve the above object, the present invention is configured as follows.

[0012] According to one aspect of the present invention, there is provided at least one two-fluid nozzle to which a gas and a liquid are supplied and which sprays the gas and the liquid; a first water supply pipe connected to a water supply source that supplies water as the liquid via a first on-off valve and that supplies the water; a second water supply pipe that connects the first water supply pipe and a liquid side inlet of the bi-fluid nozzle via a first check valve and supplies the water from the first water supply pipe to the liquid side inlet of the bi-fluid nozzle; a first air supply pipe connected via a second on-off valve to an air supply source that supplies air as the gas at a pressure lower than the supply pressure of the water, and supplies the air; a second air supply pipe that connects the first air supply pipe and a gas side inlet of the two-fluid nozzle and supplies the air from the first air supply pipe to the gas side inlet of the two-fluid nozzle, a bypass pipe that connects the first air supply pipe and the secondary side of the first check valve of the second water supply pipe via a second check valve, and supplies the air from the first air supply pipe to the second water supply pipe only when the pressure in the first air supply pipe on the primary side of the second check valve is higher than the pressure in the second water supply pipe on the secondary side of the second check valve, and discharges water from the second water supply pipe and the two-fluid nozzle; the first check valve has a predetermined cracking pressure greater than a pressure difference between a residual pressure on the upstream side of the first check valve and atmospheric pressure, When the difference between the pressure on the first water supply pipe side, which is the primary side of the first check valve, and the pressure on the second water supply pipe side, which is the secondary side, exceeds the cracking pressure of the first check valve, the water flows from the first water supply pipe to the second water supply pipe through the first check valve, the second water supply pipe, and the nozzle, thereby performing the spraying, When the first on-off valve is closed to stop the supply of water from the water supply source to the first water supply piping, the difference between the pressure on the first water supply piping side, which is the primary side of the first check valve, and the pressure on the second water supply piping side, which is the secondary side, becomes less than the cracking pressure of the first check valve, and the water does not flow from the first water supply piping to the second water supply piping through the first check valve, the second water supply piping, and the nozzle, and the spraying is stopped, and with the supply of water being stopped, the pressure on the primary side becomes higher than the pressure on the secondary side at the second check valve of the bypass piping, and the air is supplied from the first air supply piping to the second water supply piping, and the water in the second water supply piping and the nozzle is discharged. To provide an anti-drip mechanism for a two-fluid spray device. Effect of the Invention

[0013] According to the above aspect of the present invention, the air is supplied from the first air supply pipe to the second water supply pipe only when the pressure in the first air supply pipe on the primary side of the second check valve is higher than the pressure in the second water supply pipe on the secondary side of the second check valve, and a bypass pipe is provided for discharging water from the second water supply pipe and the two-fluid nozzle, and the first check valve has a predetermined cracking pressure greater than the pressure difference between the residual pressure on the primary side of the first check valve and atmospheric pressure. Therefore, when the first on-off valve is closed to stop the water supply, the pressure difference between the primary and secondary sides of the first check valve becomes less than the cracking pressure, and the water does not flow through the first water supply pipe, the second water supply pipe, and the nozzle via the first check valve, thereby stopping the spraying, and as the water supply is stopped, the primary side pressure becomes higher than the secondary side pressure at the second check valve of the bypass piping, and the air is supplied from the first air supply pipe to the second water supply pipe, thereby draining the water from the second water supply pipe and the nozzle.As a result, dripping from residual water does not occur, the time until spraying stops is shortened, and the effects of the installation height of the first check valve or the effects of external environments such as air entrapment are reduced, resulting in one of the following effects: increased robustness. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a two-fluid spray device according to an embodiment of the present invention. [Diagram 2] FIG. 1 is a perspective view showing the vicinity of a nozzle including a drip prevention mechanism of a two-fluid spray device. [Figure 3A] An explanatory diagram of a configuration in which a third check valve without cracking pressure is installed in a branch pipe for water [Figure 3B] Graph showing water pressure versus time for the configuration of FIG. 3A. [Figure 3C] An explanatory diagram of a configuration in which a bypass pipe is further provided to spray water from inside the nozzle when spraying is stopped. [Figure 3D] 1 is a graph showing the relationship between water pressure and time in a configuration in which a first check valve having a predetermined cracking pressure is provided in a branch pipe for water as a two-fluid spray device according to the present embodiment. [Figure 3E]FIG. 1 is an explanatory diagram of conditions for more reliably preventing dripping from each nozzle even when water remains in the main water pipe in this embodiment (some pipes are omitted). [Figure 4A] FIG. 1 is an explanatory diagram of a spray standby operation of the two-fluid spray device according to the present embodiment; [Figure 4B] FIG. 2 is an explanatory diagram of the spraying operation of the two-fluid spray device according to the present embodiment. [Figure 4C] FIG. 13 is an explanatory diagram of the operation of draining water from each nozzle of the two-fluid spray device according to the present embodiment. [Figure 4D] FIG. 1 is an explanatory diagram of the humidity in the installation space of the two-fluid spray device according to the present embodiment and the open / closed state of each valve. [Figure 5A] An explanatory diagram of a conventional configuration that prevents dripping by using an extrusion method. [Figure 5B] A diagram illustrating a conventional configuration that prevents dripping by releasing residual pressure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0016] FIG. 1 is a schematic diagram showing the configuration of a two-fluid spray device according to this embodiment, and FIG. 2 is an example of an integrated four-way nozzle body in which air flows in from above and branches in four directions, and water flows in from below and branches in four directions, and is a perspective view showing the vicinity of the nozzle including the drip prevention mechanism of the two-fluid spray device.

[0017] The two-fluid spray device of this embodiment comprises at least one two-fluid nozzle 1, a main water pipe 4 as an example of a first water supply pipe, a branch water pipe 6 as an example of a second water supply pipe, a main air pipe 14 as an example of a first air supply pipe, and a branch air pipe 16 as an example of a second air supply pipe.

[0018] The two-fluid nozzle 1 is arranged so as to be suspended from a fixture 41 attached to, for example, a main water pipe 4 and a main air pipe 14 of a factory, and at least one, for example, multiple, specifically four in Fig. 1 are provided, and a gas, for example air, and a liquid, for example water, are respectively supplied to the nozzles, which spray the air and water in the form of mist. As an example, the four nozzles 1 are arranged in a cross shape along the horizontal direction so that the spray nozzles of the nozzles 1 face in four directions, and the height of each spray nozzle is approximately the same.

[0019] The main water pipe 4 is arranged to extend horizontally along the ceiling of a factory, for example, and is connected to a water supply source 2 that supplies water as a liquid via a first on-off valve 3 to supply water. By opening and closing the first on-off valve 3, the supply of water from the water supply source 2 to the main water pipe 4 is started and stopped. The first on-off valve 3 is configured as a water solenoid valve unit 3A having a water solenoid valve, for example.

[0020] The branch water pipes 6 branch off from the main water pipe 4 arranged along the ceiling of a factory, for example, and are arranged mostly along the vertical direction so as to extend downward, and connect the main water pipe 4 to the liquid side inlet of the bi-fluid nozzle 1 via a first check valve 5 to supply water from the main water pipe 4 to the liquid side inlet of the bi-fluid nozzle 1. The branch water pipes 6 have, for example, a common water branch pipe 6a whose upstream end is connected to the main water pipe 4 and in which the first check valve 5 is arranged, and individual water branch pipes 6b whose respective upstream ends are connected to the downstream end of the common water branch pipe 6a and whose respective downstream ends are connected to the liquid side inlet of each bi-fluid nozzle 1.

[0021] The main air pipe 14 is arranged to extend horizontally along the ceiling of a factory, for example, and is connected via a second on-off valve 13 to an air supply source 12 that supplies air as a gas at a pressure lower than the supply pressure of water to supply air. By opening and closing the second on-off valve 13, the supply of air from the air supply source 12 to the main air pipe 14 is started and stopped. The second on-off valve 13 is configured as an air solenoid valve unit 13A having an air solenoid valve, for example.

[0022] The air branch pipe 16 branches off from the main air pipe 14 arranged, for example, along the ceiling of a factory, and is arranged mostly along the vertical direction so as to extend downward. It connects the main air pipe 14 to the gas side inlet of the two-fluid nozzle 1, and supplies air from the main air pipe 14 to the gas side inlet of the two-fluid nozzle 1.

[0023] The drain valve 30 is installed in the middle of the drain pipe 31 branched from the main water pipe 4 downstream of the first on-off valve 3, and is closed when the first on-off valve 3 is opened, and is opened when the first on-off valve 3 is closed, so that the water in the main water pipe 4 can be drained and the residual pressure can be reduced. However, when the first on-off valve 3 is closed, the drain valve 30 is temporarily opened to drain the water. If the drain valve 30 is left open, all the water in the main water pipe 4 will eventually disappear. The drain here is for reducing the water pressure in the main water pipe 4, and is not for draining all the water in the main water pipe 4. Conversely, if all the water in the main water pipe 4 is drained, the main water pipe 4 will need to be filled with water the next time it is started, which takes time and wastes water. When the first on-off valve 3 is used as an open valve, it functions as a one-way open valve.

[0024] The drain pan 32 is composed of a round tray suspended from fixtures 41 attached to the main water pipe 4 and the main air pipe 14 and positioned below the four nozzles 1. In the unlikely event that liquid drips from the nozzles of the nozzles 1, the drain pan 32 receives the dripping liquid, thereby preventing the installation space from getting wet.

[0025] Furthermore, the two-fluid spray device is provided with a bypass pipe 22 as a drip prevention mechanism, and the first check valve 5 has a predetermined cracking pressure that is greater than the pressure difference between the residual pressure on the primary side of the first check valve 5 and atmospheric pressure.

[0026] First, the bypass pipe 22 connects the main air pipe 14 to the downstream side, i.e., the secondary side, of the first check valve 5 of the branch water pipe 6 via the second check valve 21. This second check valve 21 allows air to be supplied from the main air pipe 14 to the branch water pipe 6 only when the pressure on the primary side of the second check valve 21, i.e., the pressure in the main air pipe 14, is higher than the pressure on the secondary side of the second check valve 21, i.e., the pressure on the secondary side of the first check valve 5 of the branch water pipe 6, and water in the branch water pipe 6 and the nozzle 1 is discharged from the spray nozzle of the nozzle 1. The second check valve 21 prevents neither air nor water from flowing through the bypass pipe 22 when the pressure in the main air pipe 14 is equal to or lower than the pressure on the downstream side of the first check valve 5 of the branch water pipe 6.

[0027] Furthermore, a predetermined cracking pressure is set for the first check valve 5, which is greater than the pressure difference between the residual pressure on the primary side of the first check valve 5 and the atmospheric pressure.

[0028] Here, the mechanism for preventing dripping by the arrangement of the bypass pipe 22 and the setting of a predetermined cracking pressure in the first check valve 5 will be described in detail.

[0029] The prevention of dripping is considered as follows.

[0030] First, consider a configuration in which a third check valve 105 without cracking pressure is provided in a branch pipe 106 for water, as shown in FIG. 3A.

[0031] In this configuration, when the first on-off valve 103 is closed and the drain valve 130 is opened to drain the main water pipe 104 and release the residual pressure in the main water pipe 104, the supply of water to the nozzle 101 stops. However, if the water pressure remaining on the primary side of the third check valve 105 is greater than atmospheric pressure, the pressure causes the water to flow to the nozzle side, resulting in dripping (see FIG. 3B). Therefore, it is necessary to drain the water until the residual pressure on the primary side of the third check valve 105 becomes equal to or lower than atmospheric pressure, and it takes time to stop spraying. In addition, even if the water on the primary side of the third check valve 105 does not flow, when the gas supply pressure is lost, there is a problem that a small amount of water remaining in the nozzle 101 flows out of the nozzle 101 and fine spraying occurs.

[0032] Therefore, in order to prevent fine spray from nozzle 101, a configuration may be considered in which a bypass pipe 122 is further provided to spray water from within nozzle 101 when spraying stops, as shown in FIG. 3C.

[0033] Even with this configuration, it takes time to drain the residual pressure on the primary side of the third check valve 105 until it becomes equal to or below atmospheric pressure, resulting in high running costs and problems such as low robustness due to the influence of the installation height of the third check valve 105 or air entrapment.

[0034] In order to solve these problems, as shown in Fig. 1 and Fig. 3D, the two-fluid spray device of this embodiment is provided with a first check valve 5 having a predetermined cracking pressure (greater than 0 kPa, for example, 50 kPa) greater than the pressure difference between the residual pressure on the primary side of the first check valve 5 and atmospheric pressure. With this configuration, when the difference between the residual pressure on the primary side of the first check valve 5 and atmospheric pressure becomes 50 kPa or less, the supply of water to the nozzle 1 is stopped and no dripping occurs, so there is no need to wait until the residual pressure on the primary side of the first check valve 5 becomes equal to or less than atmospheric pressure, and the time until spraying stops is shortened. In addition, the influence of the installation height of the first check valve 5 vertically below the main water pipe 4 or the influence of the external environment such as air entrapment is reduced, and robustness is improved. In other words, if the cracking pressure is set to a pressure lower than the pressure difference between the residual pressure on the primary side of the first check valve 5 and atmospheric pressure, cracking will occur and dripping will occur, but if the cracking pressure is set to a pressure higher than or equal to the pressure difference between the residual pressure on the primary side of the first check valve 5 and atmospheric pressure, cracking will not occur, i.e., water will not flow to the nozzle side via the first check valve 5, preventing dripping. Therefore, the cracking pressure is set to at least a pressure higher than the pressure difference between the residual pressure on the primary side of the first check valve 5 and atmospheric pressure.

[0035] Furthermore, the vertical positional relationship between the water solenoid valve of the first on-off valve 3 and the first check valve 5 will be described. In other words, the conditions for more reliably preventing dripping from each nozzle 1 even when water remains in the main water pipe 4 will be described with reference to FIG. 3E.

[0036] A pressure sensor (not shown) is provided in the water solenoid valve unit 3A having a water solenoid valve as the first on-off valve 3, and detects the water pressure in the main water pipe 4 downstream of the first on-off valve 3.

[0037] By opening the drain valve 30 installed in the drain pipe 31 branching off from the main water pipe 4 downstream of the first on-off valve 3, the water in the main water pipe 4 can be drained to atmospheric pressure through the drain pipe 31. The drain valve 30 is closed under the control of a control unit 50 such as a control panel when the detected value of the pressure sensor reaches a predetermined value or when a predetermined time has elapsed after the drain valve is opened.

[0038] For example, assume that the drain valve 30 is set to close when the pressure sensor detection value P1 reaches 150 kPa. In this case, when the head H1 from the main water pipe 4 on the ceiling to the water solenoid valve unit 3A is 2 m, or 2 x 9.8 = 19.6 kPa, the pressure in the main water pipe 4, i.e., the ceiling pipe pressure P2, is P2 = P1 - H1 = 150 - 19.6 = 130.4 kPa. Therefore, if the drain valve 30 is closed to cut off the flow when the detection value P1 is 20 kPa, according to Bernoulli's theorem, the pressure in the main water pipe 4 on the ceiling will be constant at 130.4 kPa.

[0039] In this case, if the first check valve 5 is disposed 1 m below the main water pipe 4, when the head H2 from the main water pipe 4 to the first check valve 5 is 1 m = 9.8 kPa, the primary pressure P3 of the first check valve 5 is P3 = P2 + H2 = 130.4 + 9.8 = 140.2 kPa. Air is supplied to the secondary side of the first check valve 5 via the bypass pipe 22 and the air branch pipe 16, and air pressure is applied. However, when the air supply is stopped and the pressure becomes atmospheric pressure, (P3 - atmospheric pressure) < cracking pressure 50 kPa, and the difference (P3 - atmospheric pressure ≒ 38.9 kPa) cannot exceed the cracking pressure 50 kPa. Therefore, the water remaining in the main water pipe 4 on the ceiling does not flow from the primary side to the secondary side of the first check valve 5, and dripping does not occur from each nozzle 1, even though water remains in the main water pipe 4. When using gauge pressure, atmospheric pressure is used as the zero reference and the value is relative to that. However, to make it easier to understand, the pressure here is explained as an absolute value.

[0040] In this case, if you wait until the pressure sensor detection value P1 reaches atmospheric pressure when draining, the pressure will be negative even without setting the cracking pressure, so water will not flow. However, this will take a long time to drain.

[0041] Therefore, a cracking pressure is set in the first check valve 5, and the time required for the pressure sensor detection value P1 to reach 150 kPa or the time lapse until it reaches 150 kPa is used to shorten the time required for the spray stopping operation. Ultimately, from the above considerations, the cracking pressure of the first check valve 5 should be set to a pressure greater than the difference between the atmospheric pressure and the sum of the pressure P2 in the main water pipe 4 and the head H2 from the main water pipe 4 to the first check valve 5.

[0042] According to such a configuration, since water remains in the pipes 4, 6 between the first on-off valve 3 and the first check valve 5, an effect of quick start-up when spraying is restarted can be obtained.

[0043] In the two-fluid spray device according to this embodiment, the second check valve 21 of the bypass piping 22 can be disposed, for example, near the secondary side of the first check valve 5. With this configuration, the distance from the secondary side of the first check valve 5 to the secondary side of the second check valve 21 via the bypass piping 22 can be shortened, so that the amount of water remaining in this path after spraying stops can be reduced. This improves robustness against dripping.

[0044] Also, as one example, the secondary side of the second check valve 21 is preferably disposed below the spray nozzle of the nozzle 1 and connected by a U-shaped pipe or the like. With this configuration, the bypass pipe 22 etc. can be shortened, and the amount of water remaining in the pipe 22 etc. can be reduced. Also, when the secondary side of the second check valve 21 is below the spray nozzle of the nozzle 1 rather than above it, water is less likely to flow through the pipe, which is more effective in preventing dripping.

[0045] Furthermore, when multiple nozzles 1 are arranged, for example, the first check valve 5 and the second check valve 21 can be arranged on the primary side of two adjacent nozzles 1. This configuration can save space and eliminates the effect on the mist spray because the first check valve 5 and the second check valve 21 are not wetted by the sprayed mist.

[0046] The first check valve 5 having cracking pressure can be used in place of a relief valve. In this configuration, the relief valve has smaller component variation in flow rate and can ensure a stable flow rate.

[0047] Next, as operations of the two-fluid spray device according to this embodiment, a spray standby operation, a spray operation, and an operation of draining water from each nozzle 1 will be described.

[0048] <Spray standby operation> As shown in Figures 4A and 4D, the first water on-off valve 3 and the second air on-off valve 13 are both closed, so the water supply pressure and air supply pressure to each of the pipes 4, 6, 14, 16 and each nozzle 1 are zero, and neither water nor air is supplied to each nozzle 1, so spraying has stopped and the system is on standby for spraying.

[0049] <Spraying operation> As shown in FIG. 4B and FIG. 4D, the first on-off valve 3 and the second on-off valve 13 are both opened so that the humidity is adjusted to a predetermined level by spraying, and for example, a water supply pressure (i.e., water pressure) of 0.449 MPa (absolute pressure) (= gauge pressure 0.348 MPa + atmospheric pressure 0.101 MPa) and an air supply pressure (i.e., air pressure) of 0.353 MPa (absolute pressure) (= gauge pressure 0.252 MPa + atmospheric pressure 0.101 MPa) are supplied to each of the pipes 4, 6, 14, 16 and each of the nozzles 1. Specifically, air with an air pressure of 0.353 MPa is supplied to each of the nozzles 1 from the air supply source 12 via the main air pipe 14 and the branch air pipe 16. Water with a water pressure of 0.449 MPa is supplied to each of the nozzles 1 from the water supply source 2 via the main water pipe 4 and the branch water pipe 6. Air and water are supplied to each of the nozzles 1 to spray mist.

[0050] Here, at point C at the upstream end of the bypass pipe 22, the air pressure of 0.353 MPa in the main air pipe 14 acts, and at point D at the downstream end, the water pressure of 0.449 MPa in the main water pipe 4 acts. Since the pressure at point C is about 0.353 MPa of the air pressure < the pressure at point D is about 0.449 MPa of the water pressure, water does not flow from point D to point C through the second check valve 21.

[0051] When air or water is flowing through the pipe, there is a pressure loss, so the pressure drops. However, if it is assumed that the main pipes for air and water use pipes with a sufficiently large diameter, the influence of the pressure loss becomes small. Therefore, it can be considered that the pressure at any point in the pipe is approximately the supply pressure. However, since the branch pipes for air and water that branch from the main pipe and lead to the nozzles have a smaller diameter than the main pipe, some pressure loss occurs. Strictly speaking, the pressures before and after the second check valve 21 do not exactly match the values of the respective supply pressures, but they are close to those values. So, it can be said that they are pressing against each other with pressures of about the respective supply pressures. Also, on the water side, it is necessary to consider the water heads H1 and H2. As this difference, several tens of kPa is taken into account on the primary side of the first check valve 5. Including this, it is recognized as being about the supply pressure.

[0052] On the other hand, before water flows through the main water pipe 4 or the like, air flows to point B on the secondary side of the first check valve 5 faster than water through the bypass pipe 22. Therefore, the air pressure acts on point B. Thus, while point B has a pressure of about 0.353 MPa of the air pressure, when water flows into the main water pipe 4, point A on the primary side of the first check valve 5 has a pressure of about 0.449 MPa of the water pressure in the main water pipe 4. Therefore, since the pressure difference between point A and point B exceeds the cracking pressure of 50 KPa, water flows from point A to point B through the first check valve 5, and water is supplied to each nozzle 1 through the water branch pipe 6.

[0053] <Operation of draining water in each nozzle 1> As shown in Figures 4C and 4D, when spraying is stopped after the humidity reaches a predetermined level, the first water on-off valve 3 is closed to stop the water (at this time, for example, P1 does not become atmospheric pressure because there is residual pressure in the main water pipe 4). Therefore, the drain valve 30 of the drain pipe 31, which is branched and connected to the main water pipe 4 downstream of the first on-off valve 3, is opened to drain the water in the main water pipe 4 and reduce the residual pressure, thereby lowering the water pressure and maintaining a negative pressure. When the water supply is stopped, only air is supplied to the main air pipe 14 as it is, and continues to be supplied to each nozzle 1 via the branch air pipe 16. At this time, the air supplied to the main air pipe 14 flows through the bypass pipe 22 to the branch water pipe 6 and each nozzle 1, and the water in the bypass pipe 22, the branch water pipe 6, and each nozzle 1 is blown away to drain the water.

[0054] Specifically, the air pressure of about 0.353 MPa from the main air pipe 14 acts on point C of the bypass pipe 22, and the water pressure acting on point D disappears, resulting in atmospheric pressure. Then, because the air pressure of about 0.353 MPa at point C is greater than the atmospheric pressure at point D, air flows from point C to point D via the second check valve 21. As a result, all water in the pipes 22, 6 and nozzle 1 from the bypass pipe 22 through the water branch pipe 6 to the nozzle 1 is blown away and discharged. After all the water in each nozzle 1 has been blown away, the air supply is stopped. "All the water has been blown away" refers to, for example, 10 seconds later, which differs depending on the length of the pipes under time control.

[0055] On the other hand, at point B, an air pressure of about 0.353 MPa acts until the air supply is stopped, and at point A, because the water supply is stopped, the residual pressure is smaller than the sum of atmospheric pressure and cracking pressure, and the pressure difference between the two does not exceed the cracking pressure of 50 kPa of the first check valve 5, so even if water remains in the main water pipe 4, that water will not flow from point A to point B. The cracking pressure is designed so that the primary side pressure P3 of the first check valve 5 (residual pressure when water supply is stopped) - atmospheric pressure < cracking pressure, so the primary side pressure P3 of the first check valve 5 will be discharged until it becomes atmospheric pressure + cracking pressure.

[0056] <Spray standby operation> As shown in Figures 4A and 4D, by stopping the air supply after blowing away all the water in each nozzle 1, the first water on-off valve 3 and the second air on-off valve 13 are also closed, so that the water supply pressure and air supply pressure to each pipe 4, 6, 14, 16 and each nozzle 1 are zero, and neither water nor air is supplied to each nozzle 1.

[0057] The height from the maximum height of the main water pipe 4 to point A is, for example, a maximum of 2 m (approximately 20 kPa), and if the height from the main water pipe 4 to the water solenoid valve unit 3A is a maximum of 3 m (approximately 30 kPa), the cracking pressure of the first check valve 5 does not exceed 50 kPa, so water will not flow with the head from the main water pipe 4.

[0058] When spraying is stopped (standby), the primary side of the first check valve 5 in the water path is full of water and is being pushed by the water head. Even if there is residual water on the secondary side of the first check valve 5, it can be considered to be at atmospheric pressure.

[0059] On the other hand, when spraying, air flows from the bypass path 22 to the secondary side of the first check valve 5, and the air pressure drops slightly due to the effect of pressure loss relative to the air supply pressure, but this is considered to be negligible, and the air pressure on the secondary side of the first check valve 5 can be considered as the "air supply pressure". On the other hand, cracking pressure is applied to the primary side of the first check valve 5, and initially, there is residual pressure without water passing through, and as part of the residual pressure, a head is applied in the vertical direction. When water supply begins, the water pressure rises and a situation is created in which the water supply pressure + head pressure is applied. The first check valve 5 finally opens when the pressure on the primary side of the first check valve 5 (= water supply pressure + head pressure) > air supply pressure (- air pressure loss (ignored as negligible)) + cracking pressure. When water begins to flow out, the pressure loss in the water piping must also be taken into consideration, so the water pressure on the primary side of the first check valve 5 is then equal to the water supply pressure + head pressure - pressure loss. Pressure loss also occurs in the first check valve itself when water passes through. The water supply pressure is defined as the pressure (P1) supplied to the main water piping 4 from the solenoid valve unit 3A having the first water on-off valve 3.

[0060] According to the above embodiment, air is supplied from the main air pipe 14 to the water branch pipe 6 only when the pressure in the main air pipe 14 on the primary side of the second check valve 21 is higher than the pressure in the water branch pipe 6 on the secondary side of the second check valve 21, and a bypass pipe 22 is provided for discharging water from the water branch pipe 6 and the nozzle 1, and the first check valve 5 has a predetermined cracking pressure greater than the pressure difference between the residual water pressure on the primary side of the first check valve 5 and atmospheric pressure. For this reason, when the first on-off valve 3 is closed to stop the water supply, the pressure difference between the primary and secondary sides of the first check valve 5 becomes less than the cracking pressure, so that water does not flow through the main water pipe 4, the branch water pipe 6, and the nozzle 1 via the first check valve 5, and spraying stops. In addition, as the water supply stops, the pressure on the primary side becomes higher than the pressure on the secondary side at the second check valve 21 of the bypass piping 22, and air is supplied from the main air pipe 14 to the branch water pipe 6, draining the water in the branch water pipe 6 and the nozzle 1. As a result, no dripping occurs due to residual water, the time until spraying stops is shortened, and the effects of the installation height of the first check valve 5 or the effects of external environments such as air entrapment are reduced, resulting in increased robustness.

[0061] In addition, by appropriately combining any of the various embodiments or modifications described above, it is possible to achieve the effects of each of them. In addition, combinations of embodiments, combinations of examples, or combinations of embodiments and examples are possible, and combinations of features of different embodiments or examples are also possible. (Additional Note) The above description of the embodiments discloses the following techniques.

[0062] (Technology 1) At least one two-fluid nozzle to which a gas and a liquid are supplied and which sprays the gas and the liquid; a first water supply pipe connected to a water supply source that supplies water as the liquid via a first on-off valve and that supplies the water; a second water supply pipe that connects the first water supply pipe and a liquid side inlet of the two-fluid nozzle via a first check valve and supplies the water from the first water supply pipe to the liquid side inlet of the two-fluid nozzle; a first air supply pipe connected via a second on-off valve to an air supply source that supplies air as the gas at a pressure lower than the supply pressure of the water, and supplies the air; a second air supply pipe that connects the first air supply pipe and a gas side inlet of the two-fluid nozzle and supplies the air from the first air supply pipe to the gas side inlet of the two-fluid nozzle, a bypass pipe that connects the first air supply pipe and the secondary side of the first check valve of the second water supply pipe via a second check valve, and supplies the air from the first air supply pipe to the second water supply pipe only when the pressure in the first air supply pipe on the primary side of the second check valve is higher than the pressure in the second water supply pipe on the secondary side of the second check valve, and discharges water from the second water supply pipe and the two-fluid nozzle; the first check valve has a predetermined cracking pressure greater than a pressure difference between the residual pressure of the water on the primary side of the first check valve and atmospheric pressure, When the difference between the pressure on the first water supply pipe side, which is the primary side of the first check valve, and the pressure on the second water supply pipe side, which is the secondary side, exceeds the cracking pressure of the first check valve, the water flows from the first water supply pipe to the second water supply pipe through the first check valve, the second water supply pipe, and the nozzle, thereby performing the spraying, When the first on-off valve is closed to stop the supply of water from the water supply source to the first water supply piping, the difference between the pressure on the first water supply piping side, which is the primary side of the first check valve, and the pressure on the second water supply piping side, which is the secondary side, becomes less than the cracking pressure of the first check valve, and the water does not flow from the first water supply piping to the second water supply piping through the first check valve, the second water supply piping, and the nozzle, and the spraying is stopped, and with the supply of water being stopped, the pressure on the primary side becomes higher than the pressure on the secondary side at the second check valve of the bypass piping, and the air is supplied from the first air supply piping to the second water supply piping, and the water in the second water supply piping and the nozzle is discharged. Anti-drip mechanism for two-fluid spray device.

[0063] With this configuration, when the first on-off valve is closed to stop the water supply, the pressure difference between the primary and secondary sides of the first check valve becomes less than the cracking pressure, and the water does not flow through the first water supply piping, the second water supply piping, and the nozzle via the first check valve, thereby stopping the spraying. In addition, as the water supply is stopped, the pressure on the primary side becomes higher than the pressure on the secondary side at the second check valve of the bypass piping, and the air is supplied from the first air supply piping to the second water supply piping, thereby draining the water in the second water supply piping and the nozzle. As a result, no dripping occurs due to residual water, the time until spraying stops is shortened, and the effects of the installation height of the first check valve or the effects of external environments such as air entrapment are reduced, resulting in increased robustness.

[0064] (Technical 2) The first water supply pipe extends along a horizontal direction on a ceiling side of an installation space of the nozzle, the second water supply pipe extends along the up-down direction of the installation space of the nozzle, and the first check valve is disposed on the second water supply pipe, The cracking pressure of the first check valve is set to a pressure greater than the difference between the sum of the pressure of the first water supply pipe and the water head from the first water supply pipe to the first check valve and atmospheric pressure (i.e., P3-atmospheric pressure). The drip prevention mechanism of the two-fluid spray device described in Technology 1.

[0065] With this configuration, when the air supply is stopped and the pressure returns to atmospheric pressure after the water supply is stopped, (P3 - atmospheric pressure) < cracking pressure, and the difference (P3 - atmospheric pressure) cannot exceed the cracking pressure, so for example, water remaining in the first water supply pipe on the ceiling side does not flow from the primary side to the secondary side of the first check valve, and dripping does not occur from each nozzle even though water remains in the first water supply pipe. In addition, because water remains in the pipe between the first opening / closing valve and the first check valve, it is possible to achieve the effect of speeding up start-up when spraying is resumed.

[0066] (Technical 3) The second check valve of the bypass piping is disposed near the secondary side of the first check valve. A drip prevention mechanism for the two-fluid spray device described in Technology 1 or 2.

[0067] With this configuration, the distance from the secondary side of the first check valve to the secondary side of the second check valve via the bypass piping can be shortened, so that the amount of water remaining in this path after spraying stops can be reduced, thereby improving robustness against dripping.

[0068] (Technology 4) The secondary side of the second check valve is disposed below the spray port of the nozzle. The drip prevention mechanism for the two-fluid spray device according to any one of the first to third aspects of the present invention.

[0069] With this configuration, the bypass piping can be shortened, and less water remains in the piping. Also, when the secondary side of the second check valve is below the nozzle spray outlet rather than above it, water flows less easily through the piping, which is more effective in preventing dripping.

[0070] (Technical 5) A plurality of the nozzles are arranged, and the first check valve and the second check valve are arranged on the primary side of the nozzles. The drip prevention mechanism for the two-fluid spray device according to any one of the first to fourth aspects of the present invention.

[0071] With this configuration, it is possible to save space and, since the first check valve and the second check valve are not wetted by the sprayed mist, there is no effect on the mist spray.

[0072] (Technical 6) The first opening / closing valve is a water solenoid valve, When the cracking pressure of the first check valve is set to a pressure greater than the difference between the sum of the pressure in the first water supply pipe and the water head from the first water supply pipe to the first check valve and atmospheric pressure, the pressure in the first water supply pipe is a value obtained by subtracting the water head of the water solenoid valve from the pressure acting on the water solenoid valve. The drip prevention mechanism of the two-fluid spray device described in Technology 2.

[0073] This configuration makes it possible to achieve the effects of technique 2. [Industrial Applicability]

[0074] The drip prevention mechanism of the two-fluid spray device according to the above-mentioned aspect of the present invention does not cause dripping due to residual water, shortens the time until spraying stops, and is less affected by the installation height of the first check valve or the influence of external environments such as air entrapment, resulting in high robustness, and is useful, for example, for humidifying by spraying air and water from a two-fluid mist nozzle in a factory. [Explanation of symbols]

[0075] 1. Two-fluid nozzle 2 Water source 3 First opening and closing valve 3A Water Solenoid Valve Unit 4. Main water pipe 5. First check valve 6 Water branch pipe 6a Common branch pipe for water 6b Individual branch piping for water 12 Air supply source 13 Second opening and closing valve 13A Air solenoid valve unit 14 Air main pipe 16 Air branch pipe 21 Second check valve 22 Bypass piping 30 Drain valve 31 Drainage piping 32 Drain pan 41 Fixtures 50 Control section 101 Nozzle 102 Water source 103 Water control valve 104 Water main pipe 105 Third check valve 106 Water branch pipe 112 Air supply source 113 Air control valve 114 Main air pipe 116 Air branch pipe 121 On-off valve 122 Bypass piping 125 Check valve 130 Drain valve H1 Head from ceiling water main pipe 4 to water solenoid valve unit 3A H2 Head from the water main pipe 4 to the first check valve 5 P1 Pressure sensor detection value P2 Pressure of water main pipe 4 P3 Primary pressure of first check valve 5

Claims

1. At least one two-fluid nozzle to which a gas and a liquid are supplied and which sprays the gas and the liquid; a first water supply pipe connected to a water supply source that supplies water as the liquid via a first on-off valve and that supplies the water; a second water supply pipe that connects the first water supply pipe and a liquid side inlet of the bi-fluid nozzle via a first check valve and supplies the water from the first water supply pipe to the liquid side inlet of the bi-fluid nozzle; a first air supply pipe connected via a second on-off valve to an air supply source that supplies air as the gas at a pressure lower than the supply pressure of the water, and supplies the air; a second air supply pipe connecting the first air supply pipe and a gas side inlet of the two-fluid nozzle and supplying the air from the first air supply pipe to the gas side inlet of the two-fluid nozzle, a bypass pipe that connects the first air supply pipe and the secondary side of the first check valve of the second water supply pipe via a second check valve, and supplies the air from the first air supply pipe to the second water supply pipe only when the pressure in the first air supply pipe on the primary side of the second check valve is higher than the pressure in the second water supply pipe on the secondary side of the second check valve, and discharges water from the second water supply pipe and the two-fluid nozzle; the first check valve has a predetermined cracking pressure greater than a pressure difference between the residual pressure of the water on the primary side of the first check valve and atmospheric pressure, When the difference between the pressure on the first water supply pipe side, which is the primary side of the first check valve, and the pressure on the second water supply pipe side, which is the secondary side, exceeds the cracking pressure of the first check valve, the water flows from the first water supply pipe to the second water supply pipe through the first check valve, the second water supply pipe, and the nozzle, thereby performing the spraying, When the first on-off valve is closed to stop the supply of water from the water supply source to the first water supply piping, the difference between the pressure on the first water supply piping side, which is the primary side of the first check valve, and the pressure on the second water supply piping side, which is the secondary side, becomes less than the cracking pressure of the first check valve, so that the water does not flow from the first water supply piping to the second water supply piping through the first check valve, the second water supply piping, and the nozzle, and the spraying is stopped, and with the supply of water being stopped, the pressure on the primary side becomes higher than the pressure on the secondary side in the second check valve of the bypass piping, so that the air is supplied from the first air supply piping to the second water supply piping, and the water in the second water supply piping and the nozzle is discharged. Anti-drip mechanism for two-fluid spray device.

2. The first water supply pipe extends along a lateral direction on a ceiling side of an installation space of the nozzle, The second water supply pipe extends along a vertical direction of the installation space of the nozzle, and the first check valve is disposed on the second water supply pipe, The cracking pressure of the first check valve is set to a pressure greater than a difference between the sum of the pressure of the first water supply pipe and the water head from the first water supply pipe to the first check valve and atmospheric pressure. The drip prevention mechanism for the two-fluid spray device according to claim 1.

3. The second check valve of the bypass piping is disposed near the secondary side of the first check valve. The drip prevention mechanism for the two-fluid spray device according to claim 1 or 2.

4. The secondary side of the second check valve is disposed below the spray port of the nozzle. The drip prevention mechanism for the two-fluid spray device according to claim 1 or 2.

5. A plurality of the nozzles are arranged, and the first check valve and the second check valve are arranged on the primary side of the nozzles. The drip prevention mechanism for the two-fluid spray device according to claim 1 or 2.

6. The first opening / closing valve is a water solenoid valve, When the cracking pressure of the first check valve is set to a pressure greater than the difference between the sum of the pressure in the first water supply pipe and the water head from the first water supply pipe to the first check valve and atmospheric pressure, the pressure in the first water supply pipe is a value obtained by subtracting the water head of the water solenoid valve from the pressure acting on the water solenoid valve. The drip prevention mechanism for the two-fluid spray device according to claim 2.

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