Droplet ejection device

Abstract

To jet a liquid in a preferable droplet state.SOLUTION: A droplet jet device 25 for forming a liquid 3 into a droplet and jetting the liquid 3 includes a body 27 having a flow channel 10 flowing the liquid 3 therein, and a jet nozzle 11 having at least one nozzle hole 13, wherein when the number of nozzle holes is represented by N, a diameter of the nozzle hole is represented by r (m), a peripheral length of a cross section of the flow channel in contact with the liquid 3 is represented by L (m), the following expression is satisfied. The liquid is jetted using the droplet jet device 25 having the configuration, and thereby can jet the liquid in a preferable droplet state.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a droplet ejection device. [Background technology]

[0002] Conventionally, various droplet spraying devices that spray liquid in the form of droplets have been used in cleaning devices, beauty devices, etc. For example, Patent Document 1 discloses a foaming nozzle structure that can eject a spray of liquid by forming bubbles in a continuous flow. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 4-500038 Summary of the Invention [Problem to be solved by the invention]

[0004] A droplet ejection device that ejects liquid in the form of droplets, when used in, for example, a cleaning device or a beauty device, impacts droplets against an object or human skin to break up the object or cleanse the human skin. In such cases, it is necessary for the liquid to be ejected as droplets with good linearity from the ejection nozzle of the droplet ejection device. However, with the foaming nozzle structure disclosed in Patent Document 1, the ejected liquid is mixed with air to form foam and is ejected as a spray. With a configuration that ejects liquid as a spray, the liquid cannot be ejected as droplets with good linearity, and it may not be possible to say that the liquid is ejected in the form of desirable droplets. [Means for solving the problem]

[0005] In order to solve the above problems, the droplet ejection device of the present invention is a droplet ejection device that sprays droplets of a liquid, and is characterized by comprising a main body having a flow path through which the liquid flows, and an ejection nozzle having at least one nozzle hole, and is characterized in that, when the number of the nozzle holes is N, the diameter of the nozzle hole is r (m), and the perimeter of the cross section of the flow path in contact with the liquid is L (m), the following formula is satisfied:

[0006]

number

[0007] Another droplet ejection device according to the present invention for solving the above problem is a droplet ejection device that ejects droplets of a liquid, and is characterized in that it comprises a main body having a flow path therein through which the liquid flows, and an ejection nozzle having at least one nozzle hole, wherein the flow path has a circular cross-sectional shape, and where N is the number of nozzle holes, r (m) is the diameter of the nozzle hole, and R (m) is the diameter of the flow path, the following formula is satisfied:

[0008]

number

[0009] A further droplet ejection device according to the present invention for solving the above problem is a droplet ejection device that ejects droplets of a liquid, and is equipped with a main body having a flow path through which the liquid flows, and an ejection nozzle having at least one nozzle hole, wherein the flow path has a rectangular cross-sectional shape, and where N is the number of nozzle holes, r is the diameter of the nozzle hole, a is the length of one side of the cross-section of the flow path, and b is the length of the other side of the cross-section of the flow path, the following formula is satisfied:

[0010]

number

[0011] [Figure 1]1 is a schematic diagram illustrating the overall configuration of a droplet ejecting device according to a first embodiment of the present invention. [Figure 2] Schematic diagram of an injection nozzle when the cross section of the flow path is circular. [Figure 3] A graph with the value of s on the vertical axis and temperature on the horizontal axis. [Figure 4] A graph with the value of s on the vertical axis and the medium on the horizontal axis. [Figure 5] Schematic diagram of an injection nozzle when the cross section of the flow path is rectangular. [Figure 6] Schematic diagram of an injection nozzle when the cross section of the flow path is square. [Figure 7] Schematic diagram of an injection nozzle when the cross section of the flow path is polygonal. [Figure 8] FIG. 10 is a schematic diagram of an injection nozzle having a plurality of (two) nozzle holes. [Figure 9] FIG. 10 is a schematic diagram of an injection nozzle having a plurality of (four) nozzle holes. [Figure 10] Schematic diagram of an injection nozzle having multiple (seven) nozzle holes. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will now be briefly described. In order to solve the above problems, a first aspect of the droplet ejection device according to the present invention is a droplet ejection device that ejects droplets of a liquid, and is characterized by comprising a main body having a flow path through which the liquid flows, and an ejection nozzle having at least one nozzle hole, and is characterized in that, when the number of nozzle holes is N, the diameter of the nozzle hole is r (m), and the perimeter of the cross section of the flow path in contact with the liquid is L (m), the following formula is satisfied:

[0013]

number

[0014] According to this aspect, the number of nozzle holes, the diameter of the nozzle holes, and the perimeter of the cross section of the flow path are determined so as to satisfy the above formula, and by using a droplet ejection device determined in this manner, it is possible to eject liquid in the form of desirable droplets regardless of the cross section shape of the flow path.

[0015] The droplet ejecting device of the second aspect is the first aspect, characterized in that the diameter of the nozzle hole is 100 μm or more and 1 mm or less, and satisfies the following formula:

[0016]

number

[0017] According to this aspect, when the diameter of the nozzle hole is 100 μm or more and 1 mm or less, most commonly used liquids can be used and the liquid can be ejected in the form of desirable droplets regardless of the cross-sectional shape of the flow path.

[0018] The droplet ejecting device of a third aspect is the first aspect, characterized in that the diameter of the nozzle hole is 1 μm or more and 100 μm or less, and satisfies the following formula:

[0019]

number

[0020] According to this aspect, when the diameter of the nozzle hole is 1 μm or more and 100 μm or less, most commonly used liquids can be used and the liquid can be ejected in the form of desirable droplets regardless of the cross-sectional shape of the flow path.

[0021] The droplet ejecting device of the fourth aspect is the first aspect, characterized in that it satisfies the following formula:

[0022]

number

[0023] According to this aspect, almost all commonly used liquids can be used and the liquid can be ejected in the form of desirable droplets regardless of the cross-sectional shape of the flow path.

[0024] A fifth aspect of the droplet ejecting device is the fourth aspect, characterized in that the diameter of the nozzle hole is 100 μm or more and 1 mm or less, and satisfies the following formula:

[0025]

number

[0026] According to this aspect, when the diameter of the nozzle hole is 100 μm or more and 1 mm or less, most liquids commonly used in cleaning devices, beauty devices, etc. can be used and the liquid can be sprayed in the form of preferred droplets regardless of the cross-sectional shape of the flow path.

[0027] A sixth aspect of the droplet ejecting device is the droplet ejecting device of the fourth aspect, characterized in that the diameter of the nozzle hole is 1 μm or more and 100 μm or less, and satisfies the following formula:

[0028]

number

[0029] According to this aspect, when the diameter of the nozzle hole is 1 μm or more and 100 μm or less, most liquids commonly used in cleaning devices, beauty devices, etc. can be used and the liquid can be sprayed in the form of preferred droplets regardless of the cross-sectional shape of the flow path.

[0030] The droplet ejecting device of the seventh aspect is the fourth aspect, characterized in that it satisfies the following formula:

[0031]

number

[0032] According to this aspect, water or a liquid with similar properties at a temperature between 20° C. and 40° C. can be used, and the liquid can be ejected in the form of desirable droplets regardless of the cross-sectional shape of the flow path.

[0033] The droplet ejecting device of an eighth aspect is the seventh aspect, characterized in that the diameter of the nozzle hole is 100 μm or more and 1 mm or less, and satisfies the following formula: ≦100 μm≦1 mm.

[0034]

number

[0035] According to this aspect, when the diameter of the nozzle hole is 100 μm or more and 1 mm or less, water or a liquid with similar properties at a temperature of 20°C or more and 40°C or less can be used, and the liquid can be sprayed in the form of preferred droplets regardless of the cross-sectional shape of the flow path.

[0036] The droplet ejecting device of a ninth aspect is the seventh aspect, wherein the diameter of the nozzle hole is 100 μm or more and 1 mm or less, and the cross-sectional area Ac (m 2 ), it is characterized by satisfying the following formula:

[0037]

number

[0038] According to this aspect, when the diameter of the nozzle hole is 100 μm or more and 1 mm or less, water or a liquid with similar properties at a temperature of 20°C or more and 40°C or less can be used, and the liquid can be sprayed in the form of preferred droplets regardless of the cross-sectional shape of the flow path.

[0039] The droplet ejecting device of a tenth aspect is the seventh aspect, characterized in that the diameter of the nozzle hole is 1 μm or more and 100 μm or less, and satisfies the following formula:

[0040]

number

[0041] According to this aspect, when the diameter of the nozzle hole is 1 μm or more and 100 μm or less, water or a liquid with similar properties at a temperature of 20°C or more and 40°C or less can be used, and the liquid can be sprayed in the form of preferred droplets regardless of the cross-sectional shape of the flow path.

[0042] The droplet ejecting device of an eleventh aspect is the same as that of the seventh aspect, wherein the diameter of the nozzle hole is 1 μm or more and 100 μm or less, and the cross-sectional area Ac (m 2 ), it is characterized by satisfying the following formula:

[0043]

number

[0044] According to this aspect, when the diameter of the nozzle hole is 1 μm or more and 100 μm or less, water or a liquid with similar properties at a temperature of 20°C or more and 40°C or less can be used, and the liquid can be sprayed in the form of preferred droplets regardless of the cross-sectional shape of the flow path.

[0045] The droplet ejection device of the twelfth aspect is a droplet ejection device that ejects droplets of liquid, and is characterized in that it comprises a main body having a flow path through which the liquid flows, and an ejection nozzle having at least one nozzle hole, wherein the flow path has a circular cross-sectional shape, and where N is the number of nozzle holes, r (m) is the diameter of the nozzle hole, and R (m) is the diameter of the flow path, the following formula is satisfied:

[0046]

number

[0047] According to this aspect, when the cross-sectional shape of the flow path is circular, the liquid can be ejected in the form of desirable droplets.

[0048] The droplet ejection device of a thirteenth aspect is the twelfth aspect, characterized in that the following formula is satisfied:

[0049]

number

[0050] According to this aspect, when the cross-sectional shape of the flow path is circular, it is possible to use almost any liquid that is commonly used and eject the liquid in the form of desirable droplets.

[0051] The droplet ejection device of a fourteenth aspect is the thirteenth aspect, characterized in that the following formula is satisfied:

[0052]

number

[0053] According to this aspect, when the cross section of the flow path is circular, water at 20° C. to 40° C. or a liquid with similar properties can be used to eject the liquid in the form of desirable droplets.

[0054] A fifteenth aspect of the droplet ejecting device is the thirteenth aspect, characterized in that when the diameter of the nozzle hole is 1 μm or more and 100 μm or less, the following formula is satisfied:

[0055]

number

[0056] According to this aspect, when the cross-sectional shape of the flow path is circular and the diameter of the nozzle hole is 1 μm or more and 100 μm or less, most commonly used liquids can be used and the liquid can be ejected in the form of desirable droplets.

[0057] A droplet ejection device of a 16th aspect is a droplet ejection device that ejects a liquid in the form of droplets, and is characterized in that it comprises a main body having a flow path through which the liquid flows, and an ejection nozzle having at least one nozzle hole, wherein the flow path has a rectangular cross-sectional shape, and where the number of nozzle holes is N, the diameter of the nozzle hole is r, the length of one side of the cross-section of the flow path is a, and the length of the other side of the cross-section of the flow path is b, the following formula is satisfied:

[0058]

number

[0059] According to this aspect, when the cross section of the flow path is rectangular, the liquid can be ejected in the form of desirable droplets.

[0060] The droplet ejecting device of a seventeenth aspect is the sixteenth aspect, characterized in that the following formula is satisfied:

[0061]

number

[0062] According to this aspect, when the cross section of the flow path is rectangular, it is possible to use almost any liquid that is commonly used and eject the liquid in the form of desirable droplets.

[0063] The droplet ejection device of an eighteenth aspect is the seventeenth aspect, characterized in that the following formula is satisfied:

[0064]

number

[0065] According to this aspect, when the cross section of the flow path is rectangular, water at 20° C. to 40° C. or a liquid with similar properties can be used to eject the liquid in the form of desirable droplets.

[0066] A droplet ejecting device according to a nineteenth aspect is the sixteenth aspect, characterized in that the cross-sectional shape is a square, and the following formula is satisfied, where p is the length of one side of the square.

[0067]

number

[0068] According to this aspect, when the cross section of the flow path is square, the liquid can be ejected in the form of desirable droplets.

[0069] The droplet ejecting device of the twentieth aspect is the droplet ejecting device of the eighteenth or nineteenth aspect, wherein the diameter of the nozzle hole is 1 μm or more and 100 μm or less, and the cross-sectional area Ac (m 2 ), it is characterized by satisfying the following formula:

[0070]

number

[0071] According to this aspect, when the cross-sectional shape of the flow path is rectangular and the diameter of the nozzle hole is 1 μm or more and 100 μm or less, the liquid can be ejected in the form of desirable droplets using water or a liquid with similar properties at 20° C. or more and 40° C. Alternatively, when the cross-sectional shape of the flow path is square and the diameter of the nozzle hole is 1 μm or more and 100 μm or less, the liquid can be ejected in the form of desirable droplets.

[0072] <One embodiment of a droplet ejection device> A droplet sprayer 25 according to one embodiment of the present invention will be described in detail below with reference to Fig. 1. The droplet sprayer 25 is a droplet sprayer for skin cleansing that is suitable for cleaning the skin of the face, arms, hands, feet, back, etc. However, it goes without saying that the droplet sprayer 25 is not limited to being used for skin cleansing.

[0073] As shown in Figure 1, the droplet ejection device 25 according to this embodiment includes an ejection nozzle 11 having at least one nozzle hole 13 for ejecting a liquid 3, a pressurized liquid supply unit 27 for pressurizing the liquid 3 and sending it to the ejection nozzle 11, and a control unit 4 for controlling the operation of the pressurized liquid supply unit 27 to cause the liquid 3 ejected from the nozzle hole 13 to fly toward a target 9 such as skin in a state in which the liquid 3 is split from a continuous stream 5 into droplets 7.

[0074] The droplet ejection device 25 includes an ejection unit 2 having an ejection nozzle 11 that ejects liquid 3, a liquid tank 6 that stores the liquid 3 to be ejected, a pump unit that is a pressurized liquid supply unit 27, a liquid suction tube 12 that forms a flow path 10 for the liquid 3 connecting the liquid tank 6 and the pressurized liquid supply unit 27, and a liquid delivery tube 14 that also forms the flow path 10 connecting the pressurized liquid supply unit 27 and the ejection unit 2. The pressurized liquid supply unit 27 has a control unit 4 that controls the pump operation, such as the pressure of the liquid 3 that is delivered to the ejection unit 2 through the liquid delivery tube 14. In other words, the supply pressure is controlled. Here, the pressurized liquid supply unit 27 corresponds to a main body that has a flow path 10 through which the liquid 3 flows.

[0075] The droplet ejection device 25 can eject the liquid 3 from the ejection part 2 under various conditions under the control of the control part 4. A preferred example of the droplet ejection device 25 will be described below.

[0076] <Two conditions for stable droplet ejection> First, as a premise, two conditions for stable droplet ejection will be explained. As described in Jet Engineering, Vol. 13, No. 1 (1996) 86-98, etc., it is known that the form of a liquid jet ejected from a single nozzle hole 1 can be classified as follows using the jet number Je: 1. Dripping area (Je≦0.1) 2. Smooth flow region (0.1 <Je<10) 3. Wavy flow region (10≦Je≦400) 4. Spray flow area (400 <Je)

[0077] It is known that in order to stably form a droplet flow with high straightness and small variation in particle size from the injected liquid jet, it is necessary to inject the liquid 3 in the smooth flow region or the wavy flow region. That is, it is necessary to set each parameter so as to satisfy 0.1 < Je ≤ 400. Here, the jet number Je is expressed as in the following formula (1). Note that ρ is the density of the liquid (kg / m 3 ), σ is the surface tension of the liquid (N / m), v is the velocity of the liquid jet (m / s), r is the nozzle hole diameter (m), and ρa is the density of the outside air (kg / m 3 ), respectively.

[0078]

Number

[0079] Also, in order to accurately hit the target location of many droplets 7, the generated droplets 7 need to have high straightness. To generate droplets 7 with high straightness, the straightness of the liquid jet from which the droplets 7 are formed is essential. In order for the liquid jet injected from the nozzle hole 13 to have straightness, it is necessary that the liquid 3 flowing in the flow path 10 is injected from the nozzle hole 13 in a laminar flow state. The mode of the fluid flowing in the flow path 10 such as a pipe is judged based on the value of the Reynolds number Re. Generally, when Re ≤ 2300, the flow in the flow path 10 is considered to be laminar. Here, the Reynolds number Re is expressed as in the following formula (2). Note that Q is the volume flow rate (m 3 / s), Ac is the cross-sectional area of the flow path (m 2 ), DH is the hydraulic diameter (m), ν is the kinematic viscosity coefficient (m 2 / s), and μ is the viscosity coefficient (Pa·s), respectively.

[0080]

Number

[0081] <Control example when the flow path is circular> An example of ejection control of the liquid 3 by the control unit 4 when the shape of the flow path 10 is circular will be described below. Here, in FIG. 2, the left-hand drawing is a schematic diagram viewed from the ejection direction of the droplet 7, and the right-hand drawing is a side cross-sectional view corresponding to the left-hand drawing. In FIG. 2, the following parameters are schematically expressed so as to be visually understandable. Note that the shape of the flow path 10 being circular means that the cross-sectional shape of the flow path 10 in the portion adjacent to the ejection nozzle 11 is circular, and as shown in the left-hand drawing of FIG. 2, means that the cross-sectional shape of the flow path inner wall 102 is circular. However, there are no particular limitations on the shape of the flow path outer wall 101.

[0082] When the flow path 10 is a circular pipe, the hydraulic diameter is equal to the diameter of the flow path 10, so if the flow path diameter, which is the diameter of the flow path 10, is R (m), the following formula (3) is obtained.

[0083]

number

[0084] Here, when equation (3) is substituted into equation (2), the following equation (4) is obtained.

[0085]

number

[0086] Furthermore, since the equation of continuity holds between the flow path 10 and the nozzle hole 13, the volumetric flow rate Q satisfies the following equation (5): where V is the flow velocity (m / s) in the flow path 10, and A is the total cross-sectional area of ​​the nozzle hole 13 (m 2 )

[0087]

number

[0088] Furthermore, when a plurality of nozzle holes 13 having the same shape are formed, the total cross-sectional area A of the nozzle holes 13 satisfies the relationship of the following formula (6): where N is the number of nozzle holes, and An is the cross-sectional area (m 2 )

[0089]

number

[0090] Furthermore, since the cross section of the flow path 10 and the cross section of the nozzle hole 13 are circular, Ac and An are expressed as the following formulas (7) and (8) using R and r, respectively.

[0091]

number

[0092]

number

[0093] Here, by substituting each of the equations (6) to (8) into the equation (5), the following equation (9) is obtained.

[0094]

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[0095]

number

[0096] Next, we will determine the conditions for the flow path 10 and the nozzle hole 13 to stably generate droplets 7 with high straightness and small particle size variation from the liquid jet. By modifying equation (1), we obtain the following equation (10).

[0097]

number

[0098]

number

[0099] As mentioned above, in order for a droplet stream with high straightness and small particle size variation to be stably formed from the ejected liquid jet, Je≦400 must be satisfied. Substituting this condition into equation (10), we obtain the following equation (12).

[0100]

number

[0101] Furthermore, by squaring both sides of equation (9) and transforming it, we obtain the following equation (13).

[0102]

number

[0103]

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[0104] Here, if both sides of equation (10) are divided by equation (13), the following equation (14) is obtained.

[0105]

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[0106]

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[0107] On the other hand, when equation (5) is substituted into equation (4) and rearranged, the following equation (15) is obtained.

[0108]

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[0109]

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[0110]

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[0111] By squaring both sides of equation (15) and substituting the result into equation (14), and then defining m as in equation (18) below and rearranging, we obtain equation (17) below, since R > 0. Equation (17) shows that the flow path diameter R is proportional to the 3 / 2 power of the nozzle hole diameter r, with m as a proportionality constant.

[0112]

number

[0113]

number

[0114] Here, when equations (11) and (16) are substituted into equation (18), and s is defined and rearranged as in equation (20) below, it is expressed as equation (19) below.

[0115]

number

[0116]

number

[0117] From equation (20), we can see that s is determined by the physical properties of liquid 3 and the density ρa of the outside air. Here, the density ρa of the outside air is approximately 1.293 (kg / m) at a temperature of 0°C. 3 ) and remains almost constant even when the temperature changes. Therefore, ρa can be considered a constant. Therefore, s is a constant determined by the physical properties of liquid 3. From Equation (19), the following can be stated.

[0118]

Number

[0119] As described above, in order to stably form a droplet flow with high straightness and small variation in particle size from the injected liquid jet, it is necessary to satisfy 0 < Re ≤ 2300 and 0.1 < Je ≤ 400, so it becomes as shown in the following Equation (21).

[0120]

Number

number

[0125] Then, applying equation (23) to equation (17), the following equation (24) is obtained. From equation (24), it can be seen that the flow path diameter R can be determined by the nozzle hole diameter r and the physical properties of the liquid 3 flowing through the flow path 10.

[0126]

number

[0127] Next, we will consider the range of values ​​that s can take. Table 1 below shows the physical properties of water and the calculated values ​​of s for each temperature, and Figure 3 is a graph with the s value of water at each temperature on the vertical axis and temperature on the horizontal axis.

[0128] [Table 1]

[0129] From Table 1, we can see that the value of s for liquid water (0°C to 100°C) at normal pressure increases monotonically as the temperature rises. Therefore, the value of s for liquid water falls roughly within the range expressed by the following equation (25).

[0130]

number

[0131] Table 2 below summarizes the physical properties of various liquids 3, such as commercially available lotions and hair growth agents, and glass liquefied by heating, as well as the values ​​of s determined using these. Figure 4 is a graph showing the values ​​of s for the media listed in Table 2 and for water at 0°C and 100°C on the vertical axis, and the media on the horizontal axis.

[0132] [Table 2]

[0133] From Tables 1 and 2, it can be seen that the values ​​of s for various liquids except for glass fall roughly within the range of the following formula (26).

[0134]

number

[0135] In other words, assuming that the liquid 3 that is easily available to the general public is used in the droplet ejection device 25, the value of s of the liquid 3 that will flow through the flow path 10 of the droplet ejection device 25 is estimated to be approximately within the range shown in the following equation (27), which is the combined range of equations (25) and (26).

[0136]

number

[0137] Therefore, the minimum required value of m in a commonly used droplet ejection device 25 is s = 0.100 × 10, which is a value slightly smaller than the minimum value of equation (27). 4 is set to the following formula (28): Then, by setting the value of m so as to satisfy formula (28) and then designing the flow path diameter R and the nozzle hole diameter r of the droplet ejection device 25, it becomes possible to eject various types of solutions in the form of droplets onto the target object 9.

[0138]

number

[0139]

number

[0140] Here, the droplet ejection device 25 is expected to be used for cleaning or crushing the object 9, and therefore a certain degree of portability is required. However, as can be seen from equation (17), as the value of m increases, the flow path diameter R also increases proportionally. The value of m can be set to any value as long as it is within the numerical range that satisfies equation (28), but the larger the value of m, the larger the flow path 10 will become without limit. Since increasing the size of the droplet ejection device 25 is contrary to the design concept of portability, it is preferable to narrow the upper limit of m so that the flow path diameter R does not become larger than necessary. Of the liquids 3 in Tables 1 and 2, the liquid 3 that is most difficult to eject is water at 100°C, which has the largest value of s, and the value of s at that time is approximately 16.4 × 10 4 From Table 2, we can see that the values ​​of s for various lotions and hair growth agents other than water are smaller than this. Therefore, we set the value of s to s = 20.0 × 10, which is slightly larger than the maximum value of Equation (27). 4 It is estimated that if m is set to m, it will be possible to spray almost all liquids 3 expected to be used in general applications in the form of droplets. In other words, the practical upper limit of m when the droplet spraying device 25 is limited to general applications is expressed by the following formula (29).

[0141]

number

[0142]

number

[0143] Therefore, the range of the value of m required in the droplet ejection device 25 when general use is assumed is as shown in the following formula (30).

[0144]

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[0145] Then, when formula (30) is applied to formula (17), the range of the flow path diameter R is limited, and the following formula (31) is obtained.

[0146]

number

[0147] Here, squaring each side of equation (31) and rearranging gives the following equation (32). If the number of nozzle holes N, the flow path diameter R, and the nozzle hole diameter r are set so as to satisfy the following equation (32), almost all liquids 3 expected to be used in general applications can be sprayed as droplets, and therefore a droplet spraying device 25 having the flow path 10 and nozzle holes 13 can be used as a cleaning device that utilizes the impact force of the droplets of the liquid 3. In other words, by configuring the device so as to satisfy the following equation 32, when the cross-sectional shape of the flow path 10 is circular, the liquid 3 can be sprayed in the form of preferred droplets 7.

[0148]

number

[0149] Here, water at temperatures of 20°C, 30°C, and 40°C in Table 2, as well as liquids T and U, were actually sprayed, and the measured values ​​of various parameters under the conditions under which stable droplet formation was achieved are shown in Table 3.

[0150] [Table 3]

[0151] As can be seen from Table 3, the values ​​of Je and Re obtained from the parameters obtained in the experiment are within the range of values ​​assumed for calculation in the present invention. In addition, the R calculated from the design values ​​of the flow path and nozzle hole 13 that could stably spray these liquids in droplet form is 2 / (N 2 ·r 3 ) satisfies equation (32). Therefore, it can be seen that equation (32) properly indicates the conditions necessary for actual droplet ejection.

[0152] Here, in the droplet ejection device 25 using one nozzle hole 13 (N = 1), when the diameter r of the nozzle hole is specifically set, Table 4 shows the minimum value and the maximum value of the flow path diameter R allowed by Equation (32).

[0153] [Table 4]

[0154] By the way, the liquid U in Tables 2 and 3 is the liquid having the largest value of the kinematic viscosity coefficient ν among the liquids 3 whose physical property values are shown in this specification. Although the liquid U shows the maximum values for both Je and Re among the liquids 3 for which various parameters were actually measured, still Je = about 73.76 and Re = about 4.86, which are considerably smaller compared to the upper limit value of Je = 400 and the upper limit value of Re = 2300. Also, the liquid T in Tables 2 and 3 is the liquid having the smallest value of the kinematic viscosity coefficient ν among the liquids 3 whose physical property values are shown in this specification. The values of Je and Re for the liquid T are Je = 5.02 and Re = 2.57, respectively.

[0155] That is, the numerical ranges of 0.1 < Je ≤ 400 and 0.1 < Re ≤ 2300 used in the derivation of Equation (32) may be too broad. Therefore, by narrowing the ranges of Je and Re, a range of the flow path diameter R that is suitable and realistic for the actual droplet ejection device 25 is obtained. Here, based on the values of Je and Re obtained from the experiments shown in Table 3, the ranges of Je and Re are set to 1 ≤ Je ≤ 100 and 1 ≤ Re ≤ 100. Then, Equations (21) and (22) are rewritten as the following Equation (33) and the following Equation (34), and as a result, the following Equation (35) corresponding to Equation (23) is obtained.

[0156] [Equation]

[0157] [Equation]

[0158]

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[0159] Here, by applying the range of s in equation (27) to equation (35), the range of m can be narrowed down as shown in equation (36) below.

[0160]

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[0161]

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[0162] Here, when rewriting it in the same form as equation (32), the following equation (37) is obtained.

[0163]

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[0164]

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[0165] Equation (37) was also calculated based on the experimental values ​​shown in Table 3. 2 / (N 2 ·r 3 ) is a numerical range that includes all values ​​of . In other words, by configuring the flow path 10 to satisfy formula (37), when the cross-sectional shape of the flow path 10 is circular, it is possible to use most commonly used liquids 3 and eject the liquid 3 in the form of desirable droplets 7. In a droplet ejection device 25 that uses one nozzle hole 13 (N=1), when the nozzle hole diameter r is specifically set, the minimum and maximum values ​​of the flow path diameter R that are allowed by formula (37) are shown in Table 5.

[0166] [Table 5]

[0167] Furthermore, when the droplet sprayer 25 is specialized for cleaning the skin using only water, for example, it can be seen from the results in Table 3 that even the range of formula (37) is excessive. This is because the value of s for water is narrower than the range of s shown in formula (23). Furthermore, when the droplet sprayer 25 is used for skin cleaning, the droplets hit human skin, so water with a high temperature such as 60°C to 100°C is not used. Therefore, in the case of a droplet sprayer 25 intended for skin cleaning using water, the water sprayed is limited to water with a temperature of approximately 20°C to 40°C. Under these conditions, the value of s is narrowed down to the range of formula (38) below, as shown in Table 1.

[0168]

number

[0169] Furthermore, the ranges of Je and Re of water in the above temperature range can be set as 1≦Je≦15 and 1≦Re≦10 according to Table 3, and can be expressed as the following equations (39) and (40), and the range of m under these conditions is as shown in the following equation (41).

[0170]

number

[0171]

number

[0172]

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[0173]

number

[0174] Here, when equations (32) and (37) are rewritten in the same form, the following equation (42) is obtained.

[0175]

number

[0176]

number

[0177] Equation (42) is R calculated based on the experimental values ​​for water at 20°C to 40°C shown in Table 3. 2 / (N 2 ·r 3 ) is a numerical range that includes all values ​​of (42). In other words, by configuring the flow path 10 so that it satisfies formula (42), when the cross-sectional shape of the flow path 10 is circular, it is possible to spray the liquid 3 in the form of desirable droplets 7 using water at a temperature between 20°C and 40°C or a liquid 3 with similar properties. In a droplet spraying device 25 using one nozzle hole 13 (N=1), when the nozzle hole diameter r is specifically set, the minimum and maximum values ​​of the flow path diameter R allowed by formula (37) are shown in Table 6.

[0178] [Table 6]

[0179] <Control example when the flow path is rectangular> Next, we will explain the case where the cross section of the flow channel 10 is rectangular rather than circular. Here, in FIG. 5, the left-hand diagram is a schematic diagram viewed from the ejection direction of the droplet 7, and the right-hand diagram is a side cross-sectional view corresponding to the left-hand diagram. In FIG. 5, the following parameters are schematically expressed for visual understanding. Note that a rectangular flow channel shape means that the cross section of the flow channel 10 adjacent to the ejection nozzle 11 is rectangular, and as shown in the left-hand diagram of FIG. 5, the cross section of the flow channel inner wall 102 is rectangular. However, there are no particular limitations on the shape of the flow channel outer wall 101. The hydraulic diameter DH shown in Equation (3) is affected by the cross-sectional shape of the flow channel 10. The hydraulic diameter DH is defined by Equation (43) below. Here, L is the wetted perimeter of the flow channel 10, or in other words, the perimeter of the flow channel inner wall 102 at the cross section of the flow channel 10.

[0180]

number

[0181] If the cross section is a rectangle with a long side a (m) and a short side b (m), Ac=ab and L=2(a+b), so DH can be expressed as in the following equation (44).

[0182]

number

[0183] Substituting equation (44) into equation (2), we obtain the following equation (45).

[0184]

number

[0185] Even when the cross section of the flow path 10 is rectangular, the continuity equation holds between the flow path 10 and the nozzle hole 13, so equation (5) is satisfied. Furthermore, the conditions for the nozzle hole 13 are the same as when the flow path 10 is circular, so the total cross-sectional area A of the nozzle holes 13 satisfies equation (6), and the cross-sectional area An of one nozzle hole 13 satisfies equation (8). Therefore, the following equation (46) is derived.

[0186]

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[0187]

number

[0188] Furthermore, by squaring both sides of equation (46) and transforming the equation, we obtain the following equation (47).

[0189]

number

[0190]

number

[0191] Then, by dividing both sides of equation (10) by equation (47), we obtain the following equation (48).

[0192]

number

[0193]

number

[0194] On the other hand, when equation (45) is further transformed, the following equation (49) is obtained.

[0195]

number

[0196]

number

[0197]

number

[0198] Then, by squaring both sides of equation (49) and substituting the result into equation (48) and rearranging, we obtain the following equation (50).

[0199]

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[0200]

number

[0201] The calculations from this point onwards are the same as when the flow channel 10 is circular. In other words, the only difference is that R in equation (17) is replaced with 2(a+b) / π. This corresponds to the fact that when the cross section of the flow channel 10 is circular, the perimeter of the flow channel inner wall 102 was πR, but now that the cross section of the flow channel 10 is rectangular, the perimeter of the flow channel inner wall 102 has changed to 2(a+b). Therefore, when the cross section of the flow channel 10 is rectangular, equation (51) corresponding to equation (32) is as follows:

[0202]

number

[0203] Now, rearranging equation (51), we get π 2 is approximately 9.87, the following formula (52) is obtained: By configuring the flow path 10 so as to satisfy formula (52), the liquid 3 can be ejected in the form of desirable droplets 7 when the cross-sectional shape of the flow path 10 is rectangular.

[0204]

number

[0205]

number

[0206] Similarly, equation (54) corresponding to equation (37) is obtained via equation (53) below as follows: By using a configuration that satisfies equation (54) in this way, it is possible to eject the liquid 3 in the form of desirable droplets 7 using most commonly used liquids 3.

[0207]

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[0208]

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[0209]

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[0210] Similarly, equation (55) corresponding to equation (42) is as follows: In this way, by configuring the flow path 10 so as to satisfy equation (54), when the cross-sectional shape of the flow path 10 is rectangular, it is possible to eject the liquid 3 in the form of desirable droplets 7 using water at a temperature of 20°C to 40°C or a liquid 3 having similar properties.

[0211]

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[0212]

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[0213]

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[0214] Here, we will explain the case where the cross-sectional shape of the flow channel 10 is square. In Figure 6, the left side is a schematic diagram viewed from the ejection direction of the droplet 7, and the right side is a side cross-sectional view corresponding to the left side. Figure 6 schematically illustrates the following parameters for visual understanding. Note that a square flow channel shape means that the cross-sectional shape of the flow channel 10 adjacent to the ejection nozzle 11 is square, and as shown in the left side of Figure 6, it means that the cross-sectional shape of the flow channel inner wall 102 is square. However, there are no particular limitations on the shape of the flow channel outer wall 101. When the cross-sectional shape of the flow channel 10 is square, if the length of one side is p (m), then p = a = b holds. Therefore, a + b in Equations (52), (54), and (55) can be changed to 2p, and the following Equations (56) and (58) can be obtained. In this way, by configuring the flow channel 10 so that Equation (58) is satisfied, the liquid 3 can be ejected in the form of a desirable droplet 7 when the cross-sectional shape of the flow channel 10 is square.

[0215]

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[0216]

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[0217]

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[0218]

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[0219]

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[0220]

number

[0221] <Example of control when the cross-sectional shape of the flow path is generalized> Furthermore, let us consider the cross-sectional shape of the flow channel 10 in a generalized manner without specifying it. Here, in FIG. 7, the left-hand diagram is a schematic diagram viewed from the ejection direction of the droplet 7, and the right-hand diagram is a side cross-sectional view corresponding to the left-hand diagram. In FIG. 7, the following parameters are schematically expressed so as to be visually understandable. Note that FIG. 7 shows an example in which the cross-sectional shape of the flow channel 10 is polygonal. The cross-sectional shape of the flow channel 10 is not limited to a polygon, and may have any curved portion. If we directly substitute equation (43), which defines the hydraulic diameter DH, into equation (2), we obtain the following equation (59).

[0222]

number

[0223] Equation (5) holds between the flow path 10 and the nozzle hole 13 regardless of the cross-sectional shape of the flow path 10. Furthermore, the conditions for the nozzle hole 13 are the same when the cross-sectional shape of the flow path is circular and when the cross-sectional shape of the flow path is rectangular, so the total cross-sectional area A of the nozzle holes 13 satisfies equation (6), and the cross-sectional area An of one nozzle hole 13 satisfies equation (8). Therefore, the following equation (60) is derived.

[0224]

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[0225]

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[0226] Furthermore, by squaring both sides of equation (60) and rearranging the equation, the following equation (61) is obtained.

[0227]

number

[0228]

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[0229] Furthermore, when both sides of equation (10) are divided by equation (61), the following equation (62) is obtained.

[0230]

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[0231]

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[0232] On the other hand, when equation (59) is further transformed, the following equation (63) is obtained.

[0233]

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[0234]

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[0235]

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[0236] Here, by squaring both sides of equation (63) and substituting the result into equation (62) and rearranging, we obtain the following equation (64).

[0237]

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[0238]

number

[0239] The calculations from this point onward are the same as when the cross-sectional shape of the flow channel 10 is circular. In other words, R in equation (17) is simply replaced with L / π. In fact, when the cross-sectional shape of the flow channel 10 is circular, the perimeter of the flow channel inner wall 102 is L = πR, so the left side of equation (64) becomes L / π = πR / π = R, and equation (17) is obtained. Furthermore, when the cross-sectional shape of the flow channel 10 is rectangular, the perimeter of the flow channel inner wall 102 is L = 2(a + b), so the left side of equation (64) becomes L / π = 2(a + b) / π, and equation (50) is obtained. In short, from the definitions of the jet number Je and the Reynolds number Re alone, it can be deduced that the perimeter L of the flow channel inner wall 102 is proportional to the 3 / 2 power of the nozzle hole radius r, regardless of the cross-sectional shape of the flow channel 10. It can also be seen that the proportionality constant in this case is mπ. Furthermore, it is also shown that the range of possible values ​​for the ratio of the perimeter L of the inner wall 102 of the flow channel at the cross section of the flow channel 10 to the 3 / 2 power of the radius r of the nozzle hole can be limited by the two conditions that "the ejected liquid 3 breaks into droplets" and "the flow in the flow channel 10 is laminar." Based on this fact, by generalizing equations (32), (37), and (42), the following equations (67) can be obtained from the following equations (65). Note that here, π 2 is calculated as 9.87.

[0240]

number

[0241]

number

[0242]

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[0243]

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[0244]

number

[0245]

number

[0246]

number

[0247]

number

[0248]

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[0249] Here, the data in Table 3 is used to calculate the perimeter L of the cross section of the flow path and the L calculated using the L. 2 / (N 2 ·r 2 ) values ​​are added and shown in Table 7.

[0250] [Table 7]

[0251] As shown in Table 7, L 2 / (N 2 ·r 2 ) is within the range of Equation (65) and Equation (66). Furthermore, the L 2 / (N 2 ·r 2 ) are all within the range of equation (67). In other words, equations (65) to (67) can be said to adequately represent the experimental values.

[0252] <Cross-sectional area of ​​the flow path> Next, calculate the perimeter L of the cross section of the flow path and the cross-sectional area Ac of the flow path that are allowed by equations (65) to (67) when the nozzle hole diameter r is specifically set. The range of the perimeter L of the cross section of the flow path can be directly determined based on equations (65) to (67). Furthermore, once the range of the perimeter L of the cross section of the flow path is determined, the maximum value of the corresponding cross-sectional area Ac of the flow path is also automatically determined. This takes advantage of the fact that when the value of the cross-sectional perimeter L is kept constant and the shape of the figure is arbitrarily changed, the area is maximum when it is circular. In other words, the area of ​​the circle corresponding to the maximum value Lmax of the perimeter L of the cross section of the flow path is the maximum value Acmax of the cross-sectional area Ac of the flow path. When the maximum perimeter Lmax of the flow path is Lmax and the maximum diameter Rmax of a circular pipe with a circular cross section, Lmax = Rmax, so the maximum cross-sectional area Acmax of the flow path is Acmax = πRmax 2 / 4=Lmax 2 In addition, when the cross-sectional shape of the flow path 10 is rectangular, the cross-sectional area of ​​the flow path 10 is maximum when the cross-sectional shape is square, and this value is Acrmax=Lmax 2 / 16. Tables 8 to 10 show the minimum perimeter Lmin, maximum perimeter Lmax, minimum diameter Rmin of a circular pipe corresponding to the minimum perimeter Lmin, maximum diameter Rmax of a circular pipe corresponding to the maximum perimeter Lmax, maximum cross-sectional area Acrmax of the flow path when the cross-sectional shape is rectangular, and maximum cross-sectional area Acmax of the flow path, calculated based on equations (65) to (67).

[0253] [Table 8]

[0254] [Table 9]

[0255] [Table 10]

[0256] <Nozzle hole diameter is 100 μm or more and 1 mm or less> The number of nozzle holes is N, the perimeter of the cross section of the flow path is L (m), and the cross-sectional area of ​​the flow path is Ac (m 2 ), if L is within the range of the following formula (68) obtained from Table 8, almost all liquids 3 can be sprayed in the form of droplets, and therefore, a droplet spraying device 25 having the flow path 10 and nozzle hole 13 can be used as a cleaning device that utilizes the impact force of droplets of the liquid 3. In other words, by adopting a configuration that satisfies formula (68) in this way, when the nozzle hole diameter r is 100 μm or more and 1 mm or less, most commonly used liquids 3 can be used to spray the liquid 3 in the form of preferred droplets 7, regardless of the cross-sectional shape of the flow path 10.

[0257]

number

[0258] Furthermore, if L falls within the range of the following formula (69) obtained from Table 9, almost all liquids 3 readily available to the general public can be sprayed as droplets, and therefore a droplet spraying device having the flow path 10 and nozzle hole 13 can be used as a portable cleaning device suitable for general use, utilizing the impact force of droplets of the liquid 3. In other words, by adopting a configuration that satisfies formula (69) in this way, when the nozzle hole diameter r is 100 μm or more and 1 mm or less, the liquid 3 can be sprayed in the form of desirable droplets 7, regardless of the cross-sectional shape of the flow path 10, using most liquids 3 commonly used in cleaning devices, beauty devices, etc.

[0259]

number

[0260] Furthermore, if the flow path 10 and the nozzle hole 13 are designed so that L falls within the range of the following formula (70) obtained from Table 10, water at a temperature of 20°C or higher and 40°C or lower can be sprayed as droplets, and therefore the droplet spraying device 25 having the flow path 10 and the nozzle hole 13 can be used as a cleaning device that utilizes the impact force of droplets of water. In other words, by configuring the device to satisfy formula (70) in this way, when the nozzle hole diameter r is 100 μm or higher and 1 mm or lower, the liquid 3 can be sprayed in the form of preferred droplets 7, regardless of the cross-sectional shape of the flow path 10, using water at a temperature of 20°C or higher and 40°C or lower or a liquid 3 with similar properties.

[0261]

number

[0262] Furthermore, if the flow path 10 and the nozzle hole 13 are designed so that Ac satisfies the following formula (71) obtained from Table 10, water at a temperature of 20°C or higher and 40°C or lower can be sprayed as droplets, and therefore a droplet spraying device 25 having the flow path 10 and the nozzle hole 13 can be used as a cleaning device that utilizes the impact force of droplets of water. In other words, by configuring the flow path 10 to satisfy formula (71) in this way, when the nozzle hole diameter r is 100 μm or higher and 1 mm or lower, water at a temperature of 20°C or higher and 40°C or lower or a liquid 3 with similar properties can be sprayed in the form of preferred droplets 7 regardless of the cross-sectional shape of the flow path 10.

[0263]

number

[0264] <Nozzle hole diameter is 1 μm or more and 100 μm or less> The number of nozzle holes is N, the perimeter of the cross section of the flow path is L (m), and the cross-sectional area of ​​the flow path is Ac (m 2), if L is within the range of the following formula (72) obtained from Table 8, almost all liquids 3 can be sprayed in the form of droplets, and therefore, a droplet spraying device 25 having the flow path 10 and nozzle hole 13 can be used as a cleaning device that utilizes the impact force of droplets of liquid 3. In other words, by adopting a configuration that satisfies formula (72) in this way, when the nozzle hole diameter r is 1 μm or more and 100 μm or less, most commonly used liquids 3 can be used to spray liquid 3 in the form of preferred droplets 7 regardless of the cross-sectional shape of the flow path 10.

[0265]

number

[0266] Furthermore, if L falls within the range of the following formula (73) obtained from Table 9, almost all liquids 3 readily available to the general public can be sprayed as droplets, and therefore a droplet spraying device having the flow path 10 and nozzle hole 13 can be used as a portable cleaning device suitable for general use, utilizing the impact force of droplets of the liquid 3. In other words, by adopting a configuration that satisfies formula (73) in this way, when the nozzle hole diameter r is 1 μm or more and 100 μm or less, the liquid 3 can be sprayed in the form of desirable droplets 7, regardless of the cross-sectional shape of the flow path 10, using most liquids 3 commonly used in cleaning devices, beauty devices, etc.

[0267]

number

[0268] Furthermore, if the flow path 10 and the nozzle hole 13 are designed so that L falls within the range of the following formula (74) obtained from Table 10, water at a temperature of 20°C or higher and 40°C or lower can be sprayed as droplets, and therefore the droplet spraying device 25 having the flow path 10 and the nozzle hole 13 can be used as a cleaning device that utilizes the impact force of the droplets of water. In other words, by configuring the device to satisfy formula (74) in this way, when the nozzle hole diameter r is 1 μm or higher and 100 μm or lower, water at a temperature of 20°C or higher and 40°C or lower or a liquid 3 with similar properties can be sprayed in the form of preferred droplets 7 regardless of the cross-sectional shape of the flow path 10.

[0269]

number

[0270] Furthermore, if the flow path 10 and the nozzle hole 13 are designed so that Ac satisfies the following formula (75) obtained from Table 10, water at a temperature of 20°C or higher and 40°C or lower can be sprayed as droplets, and therefore a droplet spraying device 25 having the flow path 10 and the nozzle hole 13 can be used as a cleaning device that utilizes the impact force of droplets of water. In other words, by configuring the flow path 10 to satisfy formula (75) in this way, when the nozzle hole diameter r is 1 μm or higher and 100 μm or lower, water at a temperature of 20°C or higher and 40°C or lower or a liquid 3 with similar properties can be sprayed in the form of preferred droplets 7 regardless of the cross-sectional shape of the flow path 10.

[0271]

number

[0272] On the other hand, if the flow path 10 and the nozzle hole 13 are designed based on Table 10 so as to satisfy the following formula (76), when the cross-sectional shape of the flow path is circular and the diameter r of the nozzle hole is 1 μm or more and 100 μm or less, the liquid 3 can be ejected in the form of a desirable droplet 7 using most commonly used liquids 3.

[0273]

number

[0274] Furthermore, if the flow path 10 and the nozzle hole 13 are designed based on Table 10 so as to satisfy the following formula (77), when the cross-sectional shape of the flow path 10 is rectangular and the diameter r of the nozzle hole is 1 μm or more and 100 μm or less, the liquid 3 can be ejected in the form of preferred droplets 7 using water at 20°C or more and 40°C or less or a liquid 3 with similar properties. Alternatively, when the cross-sectional shape of the flow path 10 is square and the diameter r of the nozzle hole is 1 μm or more and 100 μm or less, the liquid 3 can be ejected in the form of preferred droplets 7.

[0275]

number

[0276] 2...Ejection unit, 3...Liquid, 4...Control unit, 5...Continuous flow, 6...Liquid tank, 7...Liquid droplets, 9...Target object, 10...Flow path, 11...Ejection nozzle, 12...Liquid suction tube, 13...Nozzle hole, 14...Liquid delivery tube, 25...Liquid droplet ejection device, 27...Pressurized liquid supply unit (main body), 101...Flow path outer wall, 102...Flow path inner wall

Claims

1. A droplet ejection device that ejects droplets of liquid, a main body having a flow path therein through which the liquid flows, and a spray nozzle having at least one nozzle hole; The flow path has a rectangular cross-sectional shape, and when the number of nozzle holes is N, the diameter of the nozzle holes is r, the length of one side of the cross-section of the flow path is a, and the length of the other side of the cross-section of the flow path is b, the following formula is satisfied. [Equation 1]

2. The droplet ejection device according to claim 1 , A droplet ejection device characterized by satisfying the following formula: [Equation 2]

3. 3. The droplet ejection device according to claim 2, A droplet ejection device characterized by satisfying the following formula: [Equation 3]

4. The droplet ejection device according to claim 1 , The droplet ejecting device is characterized in that the cross-sectional shape is a square, and when the length of one side of the square is p, the following formula is satisfied: [Equation 4]

5. 5. The droplet ejection device according to claim 3, The diameter of the nozzle hole is 1 μm or more and 100 μm or less, and the cross-sectional area Ac (m 2 ) a droplet ejection device characterized by satisfying the following formula: [Equation 5]

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