JP2023022564A - Injection nozzle and liquid injection device - Google Patents

Abstract

To effectively clean the skin.SOLUTION: A liquid injection device includes: an injection nozzle 11 having a nozzle hole 1 through which to inject liquid 3; a pressurized liquid supply unit 27 for pressurizing liquid and sending the pressurized liquid to the injection nozzle; and a control unit 4 for controlling an operation of the pressurized liquid supply unit and flying the liquid injected through the nozzle hole in a state of being split into droplets 7 from a continuous flow 5. The liquid 3 has properties of 2.0-4.0 mPa s in viscosity and 10-50 mN/m in surface tension. The control unit controls supply pressure of the pressurized liquid supply unit 27 so that an injection velocity of the liquid injected from the injection nozzle is in the range of 10-80 m/s, and the number of droplets (number/s), which is the number of generated droplets 7 per second, is in the range of 0.40×105-9.5×105.SELECTED DRAWING: Figure 1

Description

The present invention relates to an injection nozzle suitable for washing the face or other skin by injecting liquid at high pressure, and a liquid injection apparatus having the injection nozzle.

As an example of this type of skin cleansing liquid injection device, there is one described in Japanese Patent Application Laid-Open No. 2002-200012. In this document, a cup having an opening facing outward is provided at the tip of the hand-holding portion, and the water that is pressure-fed from the discharge port of the pump is atomized and directed toward the opening through the inside of the cup. A skin cleansing device is disclosed in which a jet part for jetting is applied to the skin for use.

JP-A-61-103443

However, the skin cleanser in the above document atomizes the sprayed water and applies it to the skin, so sufficient pressing force cannot be obtained, and it is difficult to effectively cleanse the skin, especially sebum and dirt from the sebaceous glands. is difficult.

In order to solve the above problems, a liquid ejecting apparatus according to the present invention includes: an ejecting nozzle having at least one nozzle hole for ejecting liquid; a pressurized liquid supply unit that pressurizes liquid and feeds it to the ejecting nozzle; a control unit that controls the operation of a pressurized liquid supply unit to cause the liquid that is ejected from the nozzle hole to fly in a state of being divided into droplets from a continuous flow, wherein the liquid has a viscosity of is 2.0 mPa·s to 4.0 mPa·s and the surface tension is 10 mN/m to 50 mN/m, and the controller controls the velocity of the liquid jetted from the jet nozzle hole to be 10 m/s 80 m/s, and the number of droplets (number/s), which is the number of droplets generated per second by splitting into the droplets from the continuous flow, is 0.40×10 ⁵ to 9.5. The supply pressure of the pressurized liquid supply unit is controlled so as to fall within the range of ×10 ⁵ .

1 is an overall schematic configuration diagram of a liquid ejecting apparatus according to Embodiment 1 of the present invention; FIG. 4 is a high-speed photographed image obtained by photographing the continuous flow and the moving state of droplets when the supply pressure of the liquid is 0.4 MPa and 1.3 MPa in Embodiment 1. FIG. (A) is a droplet image obtained by high-speed photographing of a liquid ejection state, and (B) is an analysis image obtained by binarizing image processing to evaluate ejection and droplet characteristics from the droplet image. (A) is a high-speed photographed image of the continuous flow at the outlet of the nozzle hole photographed with the upper end face of the photographing angle of view aligned with the end face of the member containing the injection nozzle, (B) is a mixture of continuous flow and droplets. FIG. 12C is a high-speed photographed image of a portion in the process of transitioning to droplets, and (C) is a high-speed photographed image of a portion in which the continuous flow is completely split into droplets. FIG. 10 is a high-speed photographed image diagram used for explaining how to obtain the droplet velocity. FIG. 10 is a diagram of high-speed photographed images used for explaining how to obtain the droplet frequency. FIG. 5 is a diagram showing the relationship between actual values obtained by measuring the droplet frequency and calculated values obtained by performing regression analysis on the actual values for liquid A, liquid B, and liquid C; FIG. 4 is a diagram showing the relationship between actual values obtained by measuring the droplet frequency and calculated values obtained by performing regression analysis on the actual values for the liquid X. FIG. FIG. 10 is a diagram showing the relationship between the actual value obtained by measuring the droplet frequency and the calculated value/actual value for liquid A, liquid B, liquid C, and liquid X;

The present invention will first be described schematically below.
In order to solve the above problems, a first aspect of a liquid injection apparatus according to the present invention includes an injection nozzle having at least one nozzle hole for injecting liquid, and a pressurized liquid supply that pressurizes the liquid and sends it to the injection nozzle. and a control unit that controls the operation of the pressurized liquid supply unit to cause the liquid that is ejected from the nozzle hole to fly in a state where the liquid is split into droplets from a continuous flow, The liquid has a viscosity of 2.0 mPa·s to 4.0 mPa·s and a surface tension of 10 mN/m to 50 mN/m. The speed is 10 m / s to 80 m / s, and the number of droplets (number / s), which is the number of droplets generated per second by splitting into the droplets from the continuous flow, is 0.40 × 10. The supply pressure of the pressurized liquid supply unit is controlled so as to fall within the range of ^{5 5} to 9.5×10 ⁵ .
In the following description, the number of droplets (number/s), which is the number per second of the droplets that are split into the droplets from the continuous flow, is sometimes referred to as "droplet frequency".

A liquid ejecting apparatus according to the present invention ejects a continuous stream of liquid from a nozzle hole of an ejecting nozzle at a predetermined supply pressure, and then the continuous stream splits while flying to form droplets.
It is known that the size of droplets thus generated has a constant relationship with the diameter b of the nozzle hole based on the non-viscous linear theory. That is, it is known that the size of the droplet is approximately 1.88 times the diameter b of the nozzle hole, regardless of the magnitude of the supply pressure, based on the non-viscous linear theory. In other words, if the hole diameter b of the nozzle hole is specifically specified, the size of the droplet to be generated corresponding to the specified hole diameter b is determined.
Next, the ejection speed of the liquid ejected from the nozzle hole can be set by adjusting the supply pressure for the nozzle hole having the specified hole diameter b. Then, when the ejection velocity of the liquid is determined within the range of 10 m/s to 80 m/s, the velocity of the flying droplets is also determined. The droplet velocity is approximately the same as the jet velocity, and is in the range of 10 m/s to 80 m/s.
Further, there is a relation that the flow rate (ml/min) of the liquid jetted from the nozzle holes increases as the liquid jetting speed increases. The jetting speed of the liquid becomes faster when the supply pressure is increased, and becomes slower when the supply pressure is decreased. Therefore, the flow rate (ml/min) of the liquid increases as the supply pressure increases because the injection speed increases, and decreases as the supply pressure decreases as the injection speed decreases. That is, the "liquid flow rate (ml/min)" can be set by adjusting the supply pressure with respect to the nozzle hole having the specified hole diameter b.
Then, once the "liquid flow rate (ml/min)" is determined, the number of droplets (number/s), which is the number of droplets generated by splitting the continuous flow into droplets per second, is Since the "size of the droplet" to be generated is determined corresponding to the pore diameter b as shown in the above, it can be easily obtained by dividing the "flow rate (ml/min) of the liquid" by the "size of the droplet". be able to. That is, if the "liquid flow rate (ml/min)" is determined, the "number of droplets (number/s)", that is, the "droplet frequency" is also determined.
Incidentally, the above-mentioned "liquid flow rate (ml/min)" is multiplied by the number of the injection nozzle holes when there are a plurality of injection nozzle holes instead of one. This also applies to the following description.

As can be understood from the above description, in the liquid ejecting apparatus according to the present invention, the liquid ejection speed is in the range of 10 m/s to 80 m/s, and the droplet frequency can be set in the range of 0.40×10 ⁵ to 9.5×10 ⁵ .
That is, a liquid having a viscosity of 2.0 mPa s to 4.0 mPa s and a surface tension of 10 mN / m to 50 mN / m is applied at a speed of 10 m / s to 80 m / s, and the droplet It is possible to repeatedly hit an object such as skin as flying droplets with a frequency in the range of 0.40×10 ⁵ to 9.5×10 ⁵ .

According to this aspect, as can be understood from the above description, using a liquid having properties in which the viscosity and surface tension are within the above ranges, the number of droplets (number/s) generated from this liquid is It is possible to fly at the above speed and hit objects such as skin one after another. As a result, an object such as skin can be effectively washed.
In addition, physical stimulation can be applied to the skin by collision of droplets at such a droplet frequency comparable to that of ultrasonic waves, that is, the number of droplets (pieces / s), so that skin conditions such as moisturizing and elasticity can be improved. , that is, skin care can be expected.
The present inventors can effectively cleanse the skin by spraying droplets generated from the liquid having the above viscosity and surface tension at the above speed and the number of droplets (pieces/s) and applying them to the skin. This was confirmed as described later.

A liquid ejecting apparatus according to a second aspect of the present invention is characterized in that, in the first aspect, the liquid has a viscosity of 2.5 mPa·s to 3.3 mPa·s and a surface tension of 28 mN/m to 49 mN/m. and the ejection speed of the liquid ejected from the nozzle hole is in the range of 19 m/s to 57 m/s, and the droplets produced by splitting the continuous flow into the droplets per second The number of droplets (number/s), which is the number, is characterized by being in the range of 1.7×10 ⁵ to 6.4×10 ⁵ .

According to this aspect, the liquid has a viscosity of 2.5 mPa·s to 3.3 mPa·s and a surface tension of 28 mN/m to 49 mN/m, and the jet speed of the liquid is 19 m/s to 49 m/s, and the number of droplets (number/s) is in the range of 1.7×10 ⁵ to 6.4×10 ⁵ . Thereby, the effect of the first aspect can be obtained more effectively.

A liquid ejecting apparatus according to a third aspect of the present invention is the first aspect or the second aspect, wherein the control unit is capable of adjusting the supply pressure within a range of 0.3 MPa to 3.2 MPa. Characterized by

According to this aspect, the control unit can adjust the supply pressure in the range of 0.3 MPa to 3.2 MPa, so that the droplets of the flight speed and the number of droplets (number/s) can be applied to the skin or the like. can be easily realized.

A fourth aspect of the present invention is a liquid ejecting apparatus according to any one of the first aspect to the third aspect, wherein a droplet forming distance at which the continuous flow splits into droplets is 20 mm or less. characterized by
Here, the "droplet formation distance" means the distance at which the continuous flow ejected from the end face of the ejection nozzle on the liquid ejection side splits into droplets.

The droplet forming distance becomes longer as the supply pressure is increased, and becomes shorter as the supply pressure is decreased. By adjusting the supply pressure, it is possible to set the droplet forming distance within 20 mm.
According to this aspect, since the droplet forming distance is set within 20 mm, an effect is obtained in which the droplet is easily applied to a target portion of an object such as skin.

A fifth aspect of the present invention is a liquid ejecting apparatus according to any one of the first to fourth aspects, wherein the ejection nozzle has a plurality of nozzle holes.

According to this aspect, since the injection nozzle has a plurality of nozzle holes, it is possible to easily widen the washing range of the skin.

A liquid ejecting apparatus according to a sixth aspect of the present invention is characterized in that, in any one of the first to fifth aspects, the liquid is a face washing liquid or a hair liquid.
According to this aspect, for example, by spraying a milky lotion or a hair restorer that is a face wash liquid or a hair liquid, dirt and sebum adhering to the skin and scalp can be softened or removed. It can be supplied to the stratum corneum, pores, hair roots, etc., and effective skin care or scalp care can be realized.

[Embodiment 1]
A liquid ejecting apparatus according to Embodiment 1 of the present invention will be described in detail below with reference to FIG. The liquid ejecting device 25 is a liquid ejecting device that uses a skin washing liquid suitable for washing the skin of the face, arms, hands, feet, back, etc., and a hair liquid that is used for the scalp and hair.
Needless to say, the liquid ejecting device 25 is not limited to one for washing the skin.

As shown in FIG. 1 , the liquid injection device 25 according to the present embodiment includes an injection nozzle 11 having at least one nozzle hole 1 for injecting the liquid 3 and a pressurizing nozzle 11 for pressurizing the liquid 3 and sending it to the injection nozzle 11 . It comprises a liquid supply section 27 and a control section 4 that controls the operation of the pressurized liquid supply section 27 and causes the liquid 3 that is jetted from the nozzle hole 1 to fly in a state where the liquid 3 is divided into droplets 7 from the continuous flow 5 .
Furthermore, in the liquid ejecting apparatus 25 according to the present embodiment, the liquid 3 to be ejected has a viscosity of 2.0 mPa·s to 4.0 mPa·s and a surface tension of 10 mN/m to 50 mN/m. used.
Further, the controller 4 sets the jet speed of the liquid 3 jetted from the jet nozzle 11 to be in the range of 10 m/s to 80 m/s, and the droplets 7 generated by splitting the continuous flow 5 into the droplets 7 are controlled. The supply pressure of the pressurized liquid supply unit 27 is controlled so that the number of droplets per second (number/s) falls within the range of 0.40×10 ⁵ to 9.5×10 ⁵ . It is

Specifically, the liquid injection device 25 includes an injection section 2 having an injection nozzle 11 that injects the liquid 3, a liquid tank 6 that stores the liquid 3 to be injected, a pump unit that is a pressurized liquid supply section 27, A liquid suction tube 12 that forms a flow path 10 for the liquid 3 that connects the liquid tank 6 and the pressurized liquid supply section 27 , and a liquid transfer tube 14 that also forms the flow path 10 that connects the pressurized liquid supply section 27 and the ejection section 2 . and Although a soft resin material is used for the liquid suction tube 12 and the liquid delivery tube 14 in this embodiment, it is needless to say that the material is not limited to this material.
The pressurized liquid supply unit 27 is controlled by the control unit 4 in the pump operation such as the pressure of the liquid 3 sent to the injection unit 2 through the liquid transfer tube 14 . That is, the supply pressure is controlled.

<Properties of liquid to be sprayed>
As described above, in the liquid injection device 25 according to the present embodiment, the liquid 3 to be injected has a viscosity in the range of 2.0 mPa·s to 4.0 mPa·s and a surface tension in the range of 10 mN/m to 50 mN/m. properties are used.
The ranges of the viscosity and surface tension of the liquid 3 are set on the assumption that the environmental temperature in which the liquid ejecting device 25 is used is in the range of 5.degree. C. to 45.degree.
The liquid 3 used has a viscosity of 2.0 mPa·s to 4.0 mPa·s and a surface tension of 10 mN/m to 50 mN/m. The desired number of droplets can be secured even when using a liquid with low fluidity (for example, a liquid containing a hydrocarbon-based component or a synthetic compound), and the cleaning efficiency can be improved by appropriate and sufficient impact action. expected to be effective.

<Injection nozzle>
In this embodiment, the injection nozzle 11 has one nozzle hole 1, and the high-pressure liquid 3 is injected so as to advance straight from the nozzle hole 1 in order to facilitate the explanation. In the partially enlarged view of FIG. 1, reference character F indicates the direction of liquid ejection. The nozzle hole 1 has a cylindrical shape with a circular outlet in the liquid jetting direction F. As shown in FIG.
The high-pressure liquid 3 ejected from the nozzle hole 1 forms a continuous flow 5 immediately after being ejected, but immediately breaks into droplets 7 due to the surface tension of the liquid 3 . Said group of droplets 7 flies in a straight line in the direction F of liquid ejection. A group of flying droplets 7 is applied to an object such as the skin 9 one after another to wash the object.
In the partially enlarged view of FIG. 1, the dimensions of the droplet 7 and the continuous flow 5 are greatly enlarged with respect to other members, and relative dimensional relationships are ignored for the sake of easy understanding of the drawing.

<Nozzle hole diameter and droplet size>
In the liquid ejecting apparatus 25 according to this embodiment, the liquid 3 is ejected as a continuous stream 5 from the nozzle hole 1 of the ejection nozzle 11 at a predetermined supply pressure. generated.
The size of the droplet 7 generated in this way (hereinafter also referred to as “droplet diameter”) is the same as the hole diameter b of the nozzle hole 1, based on the linear theory of non-viscosity, although the explanation is partially redundant. is known to be related to That is, it is known that the size of the droplet 7 is approximately 1.88 times the hole diameter b of the nozzle hole 1, regardless of the magnitude of the supply pressure, based on the non-viscous linear theory. In other words, if the hole diameter b of the nozzle hole 1 is specifically specified, the size of the droplet 7 to be generated is determined.
For example, when the hole diameter b of the nozzle hole 1 is 0.01 mm to 0.03 mm, the size of the droplet 7 is multiplied by 1.88 to be approximately 0.0188 mm to 0.0564 mm. Furthermore, considering that the size of the droplets 7 varies somewhat depending on the smoothness of the nozzle hole 1 and environmental conditions such as temperature, the average droplet diameter is about 0.02 mm to 0.1 mm.
Here, since most of the plurality of droplets 7 are actually deformed into an elliptical shape or the like rather than a perfect sphere, the "average droplet diameter" is defined by the longest diameter portion and the shortest diameter portion. It will be obtained as an average value based on

<Supply pressure and injection speed>
If the supply pressure is increased, the ejection speed of the liquid 3 ejected from the nozzle hole 1 is increased, and if the supply pressure is lowered, the ejection speed of the liquid 3 ejected from the nozzle hole 1 is decreased.
Once the hole diameter b of the nozzle hole 1 is specified, the injection speed of the liquid 3 injected from the nozzle hole 1 is set in the range of 10 m/s to 80 m/s by adjusting the supply pressure according to the hole diameter b. It is possible to
When the ejection speed of the liquid 3 is determined, the speed of the flying droplet 7 is also determined. The velocity of the droplet 7 is approximately the same as the jetting velocity, so it is 10 m/s to 80 m/s.

<Supply pressure, injection speed, liquid flow rate and number of droplets>
If the supply pressure is increased, the ejection speed of the liquid 3 ejected from the nozzle hole 1 is increased, so the flow rate (ml/min) of the liquid ejected from the nozzle hole 1 is increased. If the supply pressure is lowered, the jetting speed of the liquid 3 jetted from the nozzle hole 1 becomes slow, so the flow rate (ml/min) of the liquid jetted from the nozzle hole 1 decreases. The supply pressure and the liquid flow rate (ml/min) have such a relationship.
Therefore, if the hole diameter b of the nozzle hole 1 is specified, the flow rate (ml/min) of the liquid ejected from the nozzle hole 1 is set to a specific flow rate by adjusting the supply pressure according to the hole diameter b. It is possible to
Then, once the "liquid flow rate (ml/min)" is determined, the number of droplets (number/s) of the droplets 7 generated by splitting the continuous flow 5 into the droplets 7 is calculated as described above. Since the "droplet size" is fixed, it can be easily obtained by dividing the "liquid flow rate (ml/min)" by the "droplet size". That is, if the "liquid flow rate (ml/min)" is determined, the "droplet frequency" is also determined.
Note that the flow rate (ml/min) of the liquid is multiplied by the number of nozzle holes 1 when there are a plurality of nozzle holes 1 instead of one. This also applies to the following description.

As can be understood from the above description, in the liquid injection device 25, the injection speed of the liquid 3 is increased by adjusting the supply pressure of the pressurized liquid supply unit 27 with respect to the specified nozzle hole diameter b. It can be set to range from 10 m/s to 80 m/s and the droplet frequency can be set to range from 0.40×10 ⁵ to 9.5×10 ⁵ .
That is, a liquid having a viscosity of 2.0 mPa s to 3.0 mPa s and a surface tension of 10 mN / m to 500 mN / m is applied at a speed of 10 m / s to 80 m / s, and the droplet It is possible to repeatedly hit an object 9 such as skin as flying droplets 7 with a frequency in the range of 0.40×10 ⁵ to 9.5×10 ⁵ .

Specifically, when the hole diameter b of the nozzle 1 is 0.024 mm, for example, the size of the generated droplet 7 is about 1.88 times the hole diameter b of the nozzle hole 1 based on the non-viscous linear theory. 0.045 mm. That is, the droplet diameter of the droplet 7 is approximately 0.05 mm.
When the supply pressure is adjusted so that the ejection speed of the liquid 3, that is, the speed of the flying droplets 7 is 10 m/s, the flow rate (ml/min) of the liquid is about 0.3, and The number of droplets generated (number/s) is approximately 1.0×10 ⁵ .
When the supply pressure is adjusted so that the ejection speed of the liquid 3, that is, the speed of the flying droplets 7, is 19 m/s, the flow rate (ml/min) of the liquid is about 0.51, which is generated per second. The number of droplets per second (number/s) is about 1.8×10 ⁵ .
When the supply pressure is adjusted so that the ejection speed of the liquid 3, that is, the speed of the flying droplets 7, is 57 m/s, the flow rate (ml/min) of the liquid is about 1.55, which is generated per second. The number of droplets per second (number/s) is about 5.4×10 ⁵ .
When the supply pressure is adjusted so that the ejection speed of the liquid 3, that is, the speed of the flying droplets 7 is 80 m/s, the flow rate (ml/min) of the liquid is about 2.2, and the liquid is generated every second. The number of droplets per second (number/s) is about 7.6×10 ⁵ .

Further, in the liquid ejecting apparatus 25 according to the present embodiment, the pressurized liquid supply unit 27 supplies the liquid 3 at a supply pressure of 0.3 MPa to 3.2 MPa for the liquid 3 ejected from the nozzle hole 1. configured to
The control unit 4 controls the supply pressure of the pressurized liquid supply unit 27 so that the injection speed V of the liquid 3 injected from the nozzle hole 1 is 10 m/s to 80 m/s. When the supply pressure is in the range of 0.3 MPa to 3.2 MPa, it is easy to achieve a state in which the jet velocity V of the liquid 3 is 10 m/s to 80 m/s. The injection pressure is not limited to the range of 0.3 MPa to 3.2 MPa, as long as the injection velocity V of the liquid 3 is 10 m/s to 80 m/s.
There is a correlation between the supply pressure and the injection speed V. When the supply pressure is 2.4 MPa, the injection speed V is approximately 60 m/s, and when the supply pressure is 3.2 MPa, the injection speed V is approximately 80 m/s.

In this embodiment, since the liquid ejection device 25 is for washing the skin, the supply pressure is set according to the hole diameter b of the nozzle hole 1 so that the liquid droplet forming distance is within 20 mm. “Droplet formation distance” means the distance at which the continuous flow 5 jetted as a continuous flow 5 from the end face 13 of the jet nozzle 11 on the liquid 3 jetting side splits into droplets 7 .
A structure for vibrating the continuous flow 5 to be jetted is provided in the jet nozzle 11 so that, in addition to controlling the supply pressure, the vibrating distance can be adjusted. can be

In this embodiment, the liquid 3 is a facial cleansing liquid containing glycerin or a hair liquid (for example, a hair restorer or hair styling agent), but a cosmetic milky lotion, water containing an anti-inflammatory component, or mixed water containing a bactericidal component is also used. may be broken.
The liquid 3 contains vitamin B2 and B6 components that suppress skin inflammation, ibuprofen piconol and dipotassium glycyrrhizinate components that are anti-inflammatory components, and resorcinol, isopropylmethylphenol and ethanol components that are sterilizing components. good too.

<Specific explanation>
FIG. 2 shows the ejection states when the diameter b of the nozzle hole 1 is 0.024 mm and the supply pressure of the liquid 3 is 0.4 MPa (upper figure) and 1.3 MPa (lower figure). FIG. 2 is a high-speed photographed image obtained by photographing a flight trajectory using a high-speed camera.
In both cases, it can be seen that the droplet forming distance is, of course, within about 20 mm, and is within 10 mm.

<Analysis value>
FIG. 3 shows droplet images obtained by high-speed photographing of a typical jetting state of the liquid in the same manner as in FIG. FIG. 10 is an analysis image diagram. Free software (ImageJ) was used for image processing. In the image processing, the photographed image is binarized, a range of droplets is selected as an analysis area, and the number of areas of each droplet 7 in the analysis area and the coordinates of the center 15 of each droplet 7 are obtained. rice field.
≪Droplet diameter≫
Here, the droplet diameter (mm) was obtained by obtaining the projected area of each droplet 7 from the number of areas of each droplet 7, assuming this to be the projected area of a sphere, and obtaining the average value from the diameter.
In the analysis, the projected area of each droplet 7 within the rectangular frame 16 of the binarized droplet image was obtained, and droplets 7 clearly smaller in diameter than the other droplets 7 were regarded as satellites and excluded. . Further, the droplet center axis deviation was determined as the maximum difference between the center coordinates of each droplet 7 .
When the hole diameter b of the nozzle hole 1 is 0.024 mm, the diameter of the droplets 7 split from the jetted continuous flow 5 is about 0.05 to 0.06 mm. It was confirmed to be consistent with the non-viscous linear theory.

≪Dropletization distance≫
In FIG. 4, (A) is a high-speed photographed image of the continuous flow 5 at the outlet of the nozzle hole 1 photographed with the upper end face of the photographing angle of view aligned with the end face of the member in which the injection nozzle 11 is accommodated, and (B) is a continuous flow image. A high-speed photographed image of a portion in the transition process of droplet formation in which the stream 5 and droplets 7 are mixed, and (C) is a high-speed photographed image of a portion in which the continuous flow 5 is completely split into droplets 7. is. The droplet forming distance was determined based on the distance moved from the state of the continuous flow 5 to the state of (C).
When the hole diameter b of the nozzle hole 1 was 0.024 mm, the droplets 7 traveled straight, and by adjusting the supply pressure, the droplet forming distance could be set within 20 mm.
Further, the maximum axial deviation of the droplet center 15 with respect to the central axis 17 of the injection nozzle 1 is 0.2 mm. Therefore, it is possible to irradiate the target location with the droplet 7 .

≪Velocity of droplet≫
As shown in FIG. 5, the droplet speed is determined by selecting two images from images taken with a high-speed camera of a state in which the continuous flow 5 is completely split into droplets 7 and flying. was obtained by dividing the moving distance d of the two images by the photographing time interval of the two images.
The moving distance d was obtained from the length per pixel determined from the angle of view of the photographed image, and the photographing time interval was obtained from the photographing speed (frame rate).
When the diameter b of the nozzle hole 1 was 0.024 mm, the droplet velocity could be reduced to about 60 m/s or less in the range of the supply pressure of 2.4 MPa or less. As a result, it is possible to prevent the impact pressure of the droplets 7 from being too strong, and the device can be used safely on the irradiation site such as the skin or scalp.

<<Droplet frequency (number of droplets (pieces/s))>>
As shown in Fig. 6, the droplet frequency (= number of droplets per second) is obtained by calculating the average number of droplets existing within the angle of view of the photographed image, and calculating the dimension (length) of the angle of view of the droplet. The average distance between droplets was obtained by dividing by the number, and the droplet velocity was obtained by dividing the average distance between droplets. For example, in FIG. 6, the average number of droplets formed in the nozzle hole 1 corresponding to the droplet 7 within the rectangular frame 18 is seven. The number of other nozzle holes 1 is also almost the same and is seven.
The average distance was calculated based on the length per pixel determined from the angle of view of the captured image.
The droplet frequency increases with increasing velocity of the droplets. Therefore, by varying the speed of the droplets, more impact action can be achieved, and more efficient cleaning can be expected.

As described above, dirt on the irradiation site of the object 9, for example, dirt and lipid accumulated on the skin and scalp, especially at the root of the hair, is determined by the droplet speed and droplet frequency (number of droplets (pieces/s) ), the impact action softens the dirt and makes it easier to remove. Furthermore, the droplets 7 are efficiently supplied to the stratum corneum, pores, hair roots, etc. of the skin, and safe and effective washing can be performed while maintaining the skin in an appropriate condition. As a result, the elasticity and moisturizing condition of the skin can be maintained well.

Table 1 shows physical property values of viscosities and surface tensions of a plurality of evaluated liquids. Table 2 shows measured droplet frequencies and droplet velocities for Liquid A, Liquid B, Liquid C and Liquid X shown in Table 1. Table 3 shows the measured values of the supply pressure and the droplet forming distance for liquid A, liquid B, liquid C and liquid X shown in Table 1. Tables 2 and 3 correspond. That is, the droplet frequencies and droplet velocities in Table 2 are actually measured values corresponding to each supply pressure in Table 3.
The viscosity was measured using a viscoelasticity meter AR-G2 (manufactured by TA Instruments Japan, temperature 20°C), and the surface tension was measured using a BP-100 (manufactured by Cruz, temperature 25°C).

Regression analysis was performed on the measured values of the droplet frequency and the droplet speed of each liquid A, liquid B and liquid C in Table 2, and the droplet speed V (m / s), viscosity η (mPa s), surface tension γ Using (mN/m) as a parameter, the relational expression (1) with the droplet frequency Drop _freq (number/s) was obtained.

図７は、前記回帰分析を行った液体Ａ、液体及び液体Ｃについての実測液滴周波数（横軸）と、関係式（１）で算出した算出値すなわち算出液滴周波数（縦軸）との関係を示す図である。両者は非常に良い線形相関を示した。

FIG. 7 shows the relationship between the actually measured droplet frequencies (horizontal axis) for liquid A, liquid, and liquid C for which the regression analysis was performed, and the calculated value calculated by the relational expression (1), that is, the calculated droplet frequency (vertical axis). FIG. 4 is a diagram showing relationships; Both showed a very good linear correlation.

Next, the droplet frequency was calculated using the relational expression (1) for the liquid X, which is another liquid with known physical properties and not applied to the regression analysis. Table 4 shows the measured values of the droplet frequency, the calculated values of the droplet frequency, and the ratio of both values, that is, the calculated value/actual value, for Liquid A, Liquid B, Liquid C, and Liquid X.
FIG. 8 is a diagram showing the relationship between the measured droplet frequency (horizontal axis) and the calculated droplet frequency (vertical axis) for liquid X. In FIG. A dashed line in FIG. 8 is a line where both numerical values completely match. As can be seen from FIG. 8, the calculated droplet frequency was equal to or slightly lower than the measured droplet frequency, and a good linear correlation was observed.

FIG. 9 is a diagram showing the relationship between the actual measurement value and the calculated value/actual measurement value of the droplet frequency for liquid A, liquid B, liquid C, and liquid X shown in Table 4. In FIG. Here, the liquid C has the largest variation within the error range of ±10%, but the droplet frequency obtained from the relational expression (1) including the liquid X agrees within the error range, and the regression It was confirmed that the relational expression (1) derived by the analysis is appropriate.
As described above, the present liquid injection device 25 applies the liquid 3 having a viscosity in the range of 2.0 mPa·s to 4.0 mPa·s and a surface tension in the range of 10 mN/m to 50 mN/m from the continuous flow 5 to the droplets 7. , and the liquid droplets can be periodically and repeatedly ejected at a droplet speed of 10 m/s to 80 m/s and a droplet frequency of 0.40×10 ⁵ to 9.5×10 ⁵ droplets/s.

<Description of the effects of the first embodiment>
(1) According to the present embodiment, as can be understood from the above description, the number of droplets generated from the liquid 3 (number/s ) can be made to fly at the above-mentioned speed and hit an object 9 such as the skin one after another. As a result, it is possible to effectively clean the object 9 such as the skin.
In addition, physical stimulation can be applied to the skin by collision of droplets at such a droplet frequency comparable to that of ultrasonic waves, that is, the number of droplets (pieces / s), so that skin conditions such as moisturizing and elasticity can be improved. , that is, skin care can be expected.
(2) Further, according to the present embodiment, the control unit 4 can adjust the supply pressure in the range of 0.3 MPa to 3.2 MPa, so that the flight speed and the number of droplets (droplets/s) It is possible to easily realize that the droplet 7 of the droplet 7 is applied to the object 9 such as the skin.
(3) In addition, according to the present embodiment, the droplet forming distance is set within 20 mm, so that the effect of facilitating application of the droplet 7 to a target portion of the target object 9 such as the skin is obtained.

[Other embodiments]
Although the liquid ejecting apparatus 25 according to the embodiment of the present invention is basically configured as described above, the partial configuration may be changed or omitted without departing from the gist of the present invention. It is of course possible to do
(1) The liquid 3 used has a viscosity of 2.5 mPa·s to 3.3 mPa·s and a surface tension of 28 mN/m to 49 mN/m. It is in the range of 19 m/s to 57 m/s, and the number (number/s) of droplets 7 generated by splitting the continuous flow 5 into droplets 7 is 1.7×10 ⁵ to 6.0 m/s. If it is in the range of 4×10 ⁵ (pieces/s), the effects described in the first embodiment can be obtained more effectively.
The following effects are obtained.

(2) In the description of the above embodiment, the injection nozzle 11 has one nozzle hole 1, but if a structure is provided with a plurality of nozzle holes 1, the cleaning area can be easily expanded. In that case, the number of nozzle holes 1 is desirably determined based on the hole diameter b of the nozzle holes 1, the flow rate appropriate for use, and the desired supply pressure.
Further, by providing nozzle holes 1 with different hole diameters, droplets 7 with different droplet diameters can be ejected at the same droplet velocity. The droplet diameter does not affect the impact pressure, but the more droplets there are, the more kinetic energy they have, so the force that pushes the colliding part increases. As a result, it is possible to improve the massage effect while maintaining the detergency.

1 nozzle hole, 2 injection part, 3 liquid, 4 control part, 5 continuous flow,
6 liquid tank, 7 droplet, 9 skin, 10 channel, 11 injection nozzle,
12 liquid suction tube, 14 liquid feeding tube, 15 center, 17 central axis,
25 liquid injection device, 27 pressurized liquid supply unit,
F: Liquid injection direction, b: Diameter of nozzle hole

Claims (6)

an injection nozzle having at least one nozzle hole for injecting liquid;
a pressurized liquid supply unit that pressurizes a liquid and sends it to the injection nozzle;
a control unit that controls the operation of the pressurized liquid supply unit to cause the liquid that is ejected from the nozzle hole to fly in a state where the liquid is split into droplets from a continuous flow,
The liquid has a viscosity of 2.0 mPa·s to 4.0 mPa·s and a surface tension of 10 mN/m to 50 mN/m,
The control unit
The speed of the liquid injected from the injection nozzle hole is 10 m / s to 80 m / s,
The number of droplets (number/s), which is the number of droplets per second generated by splitting into the droplets from the continuous flow, is in the range of 0.40×10 ⁵ to 9.5×10 ⁵ . to control the supply pressure of the pressurized liquid supply,
A liquid injection device characterized by: The liquid ejecting device according to claim 1,
The liquid has a viscosity of 2.5 mPa·s to 3.3 mPa·s and a surface tension of 28 mN/m to 49 mN/m,
The jet speed of the liquid jetted from the nozzle hole is in the range of 19 m / s to 57 m / s,
The number of droplets (number/s), which is the number per second of the droplets split into the droplets from the continuous flow, is in the range of 1.7×10 ⁵ to 6.4×10 ⁵ . ,
A liquid injection device characterized by: 3. The liquid injection device according to claim 1,
The control unit can adjust the supply pressure in the range of 0.3 MPa to 3.2 MPa.
A liquid injection device characterized by: The liquid ejecting device according to any one of claims 1 to 3,
The dropletization distance at which the continuous flow splits into droplets is within 20 mm.
A liquid injection device characterized by: The liquid ejecting device according to any one of claims 1 to 4,
The injection nozzle has a plurality of the nozzle holes,
A liquid injection device characterized by: In the liquid ejecting device according to any one of claims 1 to 5,
The liquid is a face wash liquid or a hair liquid,
A skin cleansing liquid injection device characterized by:

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