JP2014068798A - Washing machine, and washing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a washing machine and a washing method capable of reducing a usage amount of detergent and saving washing costs while maintaining a washing effect without requiring special additional equipment in the washing of fiber and a fiber product.SOLUTION: A washing machine 1 includes: a water supply pipe 4 in a sealable washing tub 2; a water supply valve 8; a water supply pressure adjustment valve 7; an exhaust pipe 6; an exhaust valve 10; and a control device for controlling these. The control device introduces tap water into the washing tub 2 by supply pressure of water supply by opening the water supply valve 8 in a state where the washing tub 2 is sealed, and also, it allows air in the washing tub 2 to dissolve in the water in the washing tub 2 in such a manner that total dissolved gas concentration in water becomes 120% or more of saturation solubility under atmospheric pressure by controlling the water supply pressure adjustment valve 7 and the exhaust valve 10.

Description

  The present invention relates to a household or commercial washing machine, and more specifically to a washing machine and a washing method for reducing the amount of detergent used while maintaining a washing effect.

  In the washing of textiles and textile products, improvement of detergency, reduction of washing time, reduction of washing costs, and suppression of fabric damage are continual goals. To achieve this, detergents, auxiliaries, Development of washing machines has been continued.

  On the other hand, regardless of household use or business use, as water used for washing, for example, washing water and rinsing water, tap water, well water, lake water, river water, etc. are used as they are, or they are treated by filtration, sterilization, etc. I used it. In other words, the concentration of dissolved gas dissolved in water, such as dissolved oxygen and dissolved nitrogen, was left uncontrolled and was hardly controlled for many years. Therefore, washing and rinsing were usually performed with air-saturated water with the following exceptions.

  On the other hand, as an attempt to control the dissolved gas of washing water, Patent Document 1 discloses that the laundry is put in a sealed washing tub, and the pressure in the washing tub is changed in the decompression direction to dissolve in the washing water. A method is disclosed in which a gas that is flowing is bubbled to act on laundry. Furthermore, in order to change the pressure in the washing tub in the pressure-reducing direction, it is disclosed that the inside of the washing tub is once pressurized and then brought to normal pressure or negative pressure.

Patent Document 2 discloses a method of generating CO ₂ dissolved water by introducing tap water and CO ₂ gas in a gas cylinder into a pressure vessel, and supplying this CO ₂ dissolved water to the water in the washing tub. ing. In this method, when the CO ₂ -dissolved water is supplied to the water in the washing tub, fine bubbles of CO ₂ gas are generated in the water in the washing tub, and the effect of removing dirt from the laundry is generated by the fine bubbles. .

JP-A-5-309195 Japanese Patent Laid-Open No. 2001-87587

  In order to increase the washing power in washing, it is possible to increase the detergent concentration, raise the water temperature, raise the pH, raise the water shear rate, etc., but these methods increase the washing cost, waste water This is undesirable because it increases contamination, shrinkage of clothing, and increases in fabric damage.

Further, the methods disclosed in Patent Documents 1 and 2 require equipment for dissolving gas in washing water, equipment for generating gas bubbles from water in the washing tub, and the like. That is, the washing machine disclosed in Patent Document 1 is provided with a pump for pressurizing / depressurizing the inside of a closed washing tub. In the washing machine disclosed in Patent Document 2, CO ₂ supplied to the water in the washing tub is prepared. A pressure vessel and a CO ₂ gas cylinder are prepared to generate dissolved water. Thus, since the incidental installation regarding gas dissolution is required, there exists a subject that a washing machine becomes expensive.

  The object of the present invention is to reduce the amount of detergent used and reduce the washing cost while maintaining the cleaning effect in washing of fibers and textile products without causing these problems, further increasing labor and safety problems. It is possible to save and no special incidental equipment for gas dissolution is required.

  One embodiment of the present invention relates to a washing machine including a sealable washing tub, and includes a water supply pipe, a water supply valve, a water supply pressure adjustment valve, an exhaust pipe, an exhaust valve, and a control device.

  The water supply pipe is connected to the water supply pipe and supplies the tap water flowing through the water supply pipe to the washing tub. The water supply valve can open and close the flow path of the water supply pipe. The water supply pressure adjustment valve can adjust the pressure of tap water supplied into the washing tub through the water supply pipe. The exhaust pipe exhausts the gas in the washing tub. The exhaust valve can open and close the flow path of the exhaust pipe. The control device controls the water supply valve, the water supply pressure adjustment valve, and the exhaust valve.

  The control device opens the water supply valve in a state where the washing tub is sealed to introduce tap water into the washing tub by a water supply pressure, and controls the water supply pressure adjusting valve and the exhaust valve. The air in the washing tub is dissolved in the water in the washing tub so that the total dissolved gas concentration in the water is 120% or more of the saturation solubility under atmospheric pressure.

  Another aspect is a washing method for washing laundry in a washing tub using tap water, and after the laundry is put into the washing tub, the washing tub is sealed and the water supply is supplied by a water supply pressure. Water is introduced into the washing tub, and the pressure of tap water introduced into the washing tub and the pressure in the washing tub is controlled so that the total dissolved gas concentration in the water is 120% or more of the saturated solubility under atmospheric pressure. Thus, the gas in the washing tub is dissolved in the water in the washing tub.

  Furthermore, the aspect of this invention is described.

  As a result of investigating the effect of dissolved gas concentration on washing and rinsing, the inventor introduced tap water into a washing tub sealed under atmospheric pressure as water used for washing, such as immersion, washing, and rinsing. While pressurizing the inside of the washing tub with the supply pressure of the tap water, the dissolved gas concentration in the washing tub water (also called dissolved gas concentration or gas dissolved rate) is increased to 120% or more of the saturation solubility under atmospheric pressure. Then, by releasing the pressure in the washing tub to atmospheric pressure during the washing process such as dipping, washing, rinsing, etc., the supersaturated dissolved gas becomes fine bubbles inside the laundry fibers or on the laundry surface. It can be generated and effectively removed by raising the dirt by the fine bubbles, and it has the effect of shortening the washing time and reducing the amount of detergent used without requiring special incidental equipment for gas dissolution As a result, the inventors have intensively studied to arrive at the present invention.

  The term “laundry” as used in the present invention refers to usual laundry, that is, washing of fibrous articles, leather, fur, feathers, animal hair, or products made of these, or artificial products having these properties. In addition, washing after dyeing and the like and washing of animals such as animals and birds are also included. Among these, it is particularly effective for fibers and textile products. The present invention relates to the use of water as a washing liquid, and includes washing with water as well as those used with detergents.

  The water used for washing in the present invention refers to water used as, for example, immersion water, prewash water, laundry water, rinse water, and the like. In the present invention, in any one or a plurality of operations such as dipping, prewashing, washing, dipping, etc., tap water is introduced into a sealed washing tub, and the dissolved gas concentration is adjusted by the water supply pressure. Increased water is used.

  The water whose dissolved gas concentration is increased is water in which the gas in the washing tub is pressure-dissolved so that the total dissolved gas concentration in water is 120% or more of the saturation solubility under atmospheric pressure. The gas refers to a substance that exists as a gas at normal temperature and pressure, and examples thereof include oxygen, nitrogen, carbon dioxide, ozone, chlorine, hydrogen, and rare gases. In the case of using a mixed gas (including air) of a plurality of types of gases, each component gas must be 120% or more of the saturation solubility at each partial pressure of each component gas under the atmospheric pressure of the mixed gas. Use water dissolved under pressure. When an oxidizing gas such as ozone or chlorine is used, cleaning effects such as sterilization and bleaching by oxidizing power can be obtained in addition to the cleaning effect caused by the generation of bubbles by releasing the pressure described later. However, air (about 80% nitrogen and about 20% oxygen) is desirable as the gas used in the present invention because of its availability, cost, and safety. For example, when the air is at atmospheric pressure and 25 ° C., the dissolved nitrogen saturation solubility is about 14 mg / l, and the dissolved oxygen saturation solubility is about 8 mg / l. Since the solubility of gas in water follows Henry's law, if the absolute pressure is 1.2 atmospheres or more, the gas saturation solubility will be 120% or more at atmospheric pressure, and the gas-dissolved water will be immersed and prewashed as described later. In the washing process such as washing and rinsing, by releasing the pressure, fine bubbles are generated inside the fibers of the laundry, and the dirt is lifted to obtain a good cleaning effect.

As a method for dissolving the gas in water, any method can be used as long as the dissolved gas concentration in water can be 120% or more of the saturation solubility under atmospheric pressure, for example, pressurization of gas by a compressor, pressurization of water by a pump, Pressurization with water supply pressure, partly movable washing tub with gas-liquid co-sealing, gas dissolution with ejector, gas dissolution with turbulent flow under pressure, or a combination of these The method etc. can be illustrated. In pressurization of gas by a compressor, pressurization of water by a pump, and pressurization by water supply pressure, gas pressurized by a compressor is blown into a washing tub having a sealable structure, or water pressurized by a pump Is introduced. A device that ejects fluid and sucks the surrounding gas or liquid is called an ejector, but water is ejected from the nozzle by pump pressurization or water supply water pressure, and the surrounding gas is sucked into the water. It can also be dissolved. In particular, in the present invention, by introducing tap water normally supplied at about 1 to 7 kg / cm ² into a sealed washing tub, the gas in the washing tub is supplied into the washing tub using the supply pressure of the water tap. Dissolve under pressure in water. The method using tap water pressure is particularly suitable because the washing machine does not require a facility for pressurizing the inside of the washing tub, and only requires the washing tub to have a pressure-resistant structure.

  In the gas dissolving method, if a turbulent flow is formed by the flow of water or gas while the gas-liquid two phases are in contact with each other, the gas can be dissolved more efficiently. For example, by introducing tap water into a closed washing tub and pressurizing the inside of the washing tub with the supply water pressure of the tap water, the water in the washing tub is swung with a rotating drum or the like to improve the contact efficiency between water and gas. A method of increasing the gas and dissolving the gas in water can be exemplified.

  In the washing machine of the present invention, in the washing process such as dipping, pre-washing, washing, rinsing, etc., the laundry and water are kept in contact with each other at the same pressure as in the gas pressure dissolution, and then connected to the washing tub. When the pressure release valve provided is opened to atmospheric pressure, dissolved gas supersaturated in the water is generated as fine bubbles inside the laundry fibers or on the surface of the laundry, causing the bubbles to raise dirt. Can be effectively removed. The pressure is preferably maintained in a state where a gas-liquid two phase exists in the washing tub in order to maintain a gas dissolution equilibrium. Moreover, if the pressure release valve is installed on the liquid phase side in the washing tub, water is discharged when the pressure is released, which is not preferable. The pressure release valve is preferably installed on the gas phase side in the washing tub, and the internal pressure of the washing tub is released to atmospheric pressure by discharging the gas.

  The saturated dissolved gas concentration increases according to Henry's law if the pressure at the time of dissolution is increased, and the amount of gas generated when the pressure is released increases, so that a better cleaning effect tends to be obtained. However, a washing tub that can withstand high pressure is expensive. If the dissolved gas concentration in water exceeds 120% of the saturation solubility under atmospheric pressure, a certain cleaning effect can be obtained, so the lower limit of the dissolved gas concentration in water is 120% of the saturation solubility under atmospheric pressure, and the upper limit Is preferably determined in consideration of cost, safety and the like.

  Following the generation of fine bubbles due to pressure fluctuations to atmospheric pressure as described above, the laundry tub is further depressurized so that the total dissolved gas concentration in the water is 80% or less of the saturated solubility under atmospheric pressure, inside the fibers of the laundry, or By promoting the generation of fine bubbles on the surface of the laundry, a more powerful dirt removal effect can be obtained. In order to make the dissolved gas concentration in water 80% or less of the saturation solubility under atmospheric pressure, the absolute pressure should be 0.8 atm (608mmHg) or less, which can be easily achieved by depressurization with a vacuum pump or ejector. it can. It is possible to generate more bubbles if the degree of vacuum is further reduced below the absolute pressure of 0.8 atm (608 mmHg). However, since the amount of bubbles to increase is small, the upper limit of the vacuum level of the washing tub is the vacuum level at which the dissolved gas concentration in water is 80% of the saturated solubility under atmospheric pressure, and the lower limit is the vacuum resistance of the washing tub. It is preferable to determine the cost in consideration of the total cost.

  In the washing machine of the present invention, the generation of fine bubbles can lift and remove dirt inside the fiber, so that the amount of detergent used can be greatly reduced. In general, detergents do not continue to improve the cleaning effect according to the amount used, even if they are used above a certain amount. The use of an excessive amount of detergent not only wastes the detergent, but also increases the environmental load due to drainage, and requires more rinsing water. Therefore, a standard usage amount indicating an appropriate usage amount is set for the detergent. However, in the washing machine of the present invention, the fine bubbles assist the cleaning effect. Even if the amount is 1/3 or less of the standard use amount, a cleaning effect equivalent to the case of using the standard use amount in a conventional washing machine can be obtained.

Further, in the washing machine of the present invention, if the water used to dissolve the gas used in the washing process such as dipping, prewashing, washing, rinsing is soft water having a hardness of 50 mg CaCO ₃ / l or less, the washing effect of the detergent can be enhanced. . Soft water having a hardness of 50 mg CaCO ₃ / l can be obtained by a normal softening operation. In other words, raw water is passed through a packed bed of Na-type cation exchange resin (for example, Amberlite 120b manufactured by Rohm and Haas) at a space flow velocity of about 50h-1, and the hardness component in the raw water is exchanged with sodium ions for soft water. Get.

  Furthermore, in the washing machine of the present invention, if demineralized water having a conductivity of 100 μS / cm or less, more preferably a conductivity of 50 μS / cm or less is used as water for dissolving the gas, the washing effect of the detergent can be further enhanced. The method for desalting water is not particularly limited, and a method using an ion exchange resin or a reverse osmosis membrane can be exemplified. Use of an electrochemical deionized water production apparatus as disclosed in Japanese Patent Application Laid-Open No. 2010-29753 is preferable because it is not necessary to replace an ion exchange resin cartridge or a reverse osmosis membrane module.

The surfactant, the main component of the detergent, has a molecular structure consisting of a hydrophilic part and a hydrophobic part. By dispersing in water with affinity, it functions to stably disperse dirt in water and remove it with water drainage. When ions, especially divalent ions such as calcium and magnesium, are present in water, these ions bind to the hydrophilic portion of the surfactant, and the function of the surfactant is significantly inhibited. For this reason, when using soft water in which divalent calcium or magnesium ions are exchanged for monovalent sodium ions, a good cleaning effect can be obtained as described above. Further, when the water is desalted to remove monovalent ions, the effect of dispersing the surfactant with the soil is further enhanced as compared with soft water, and a very good cleaning effect can be obtained.
Usually, a commercially available detergent contains an auxiliary agent (chelating agent) or the like in order to prevent the surfactant from being inhibited by ions. When soft water or demineralized water is used, there is almost no inhibition of the surfactant by ions, so that a natural soap containing no auxiliary agent can provide a good cleaning effect.

  In the washing machine of the present invention, gas dissolution into water by pressurization at the time of introduction of tap water, release to atmospheric pressure by opening a pressure release valve, and subsequent decompression as necessary are immersion, prewash, washing, rinsing In at least a part of the washing process, etc., it is usually performed once and brings about a good cleaning effect. However, when the dirt is severe, it is preferable to repeat the above pressurization, release to the atmosphere, and decompression cycles as many times as necessary. A cleaning effect can be obtained.

  As described above, in the present invention, tap water is introduced into a washing tub sealed under atmospheric pressure, and the inside of the washing tub is pressurized by the supply pressure of the tap water, so that the total dissolved gas concentration in water is atmospheric pressure. After releasing the pressure by opening the pressure relief valve installed in the washing tub after pressure-dissolving the gas in the washing tub in the water in the washing tub so that it becomes 120% or more of the lower saturated solubility, The dissolved gas supersaturated in the water can be generated as fine bubbles inside the laundry fibers or on the surface of the laundry, and the bubbles can be lifted and removed by the bubbles. Furthermore, by depressurizing the washing tub and setting the total dissolved gas concentration in water to 80% or less of the saturated solubility under atmospheric pressure, the generation of fine bubbles inside the laundry fibers or on the laundry surface is promoted. A powerful dirt removal effect can be obtained. In addition, since the gas is dissolved in the water using the tap water pressure, the washing machine does not require special incidental facilities for gas dissolution, and thus the price of the washing machine can be kept low.

  Therefore, according to the washing machine of the present invention, it is possible to reduce the amount of detergent used and reduce the washing cost while maintaining the cleaning effect in the washing of fibers and textile products. do not need.

It is a schematic diagram which shows the component of the washing machine by one Example of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 schematically shows the configuration of the washing machine of this embodiment. According to FIG. 1, the washing machine 1 has a washing tub 2, and the washing tub 2 includes a rotating drum 3 that rotates the laundry together with water or water containing a detergent or the like. Furthermore, the washing tub 2 has a structure that can be sealed so that not only water leakage but also air leakage does not occur. For example, the laundry tub 2 is provided with a lid capable of opening and closing the laundry inlet, and a seal member such as packing is provided between the inlet and the lid, and the lid is fixed in a state where the inlet is hermetically closed by the lid. A locking mechanism is provided.

  A water supply pipe 4 for supplying tap water to the inside of the washing tub 2 and an exhaust pipe 6 for discharging the gas in the washing tub 6 are separately connected to the upper part of the washing tub 2. The upstream end of the water supply pipe 4 from the washing machine 1 is connected to a water faucet or a water outlet valve of the water pipe. Inside the washing machine 1, the water supply pipe 4 has a water supply pressure adjusting valve 7 for adjusting the water supply pressure. And the water supply valve 8 which opens and closes the flow path of the water supply pipe 4 is installed. Further, an exhaust valve 6 that opens and closes the flow path of the exhaust pipe 6 is installed in the exhaust pipe 6 inside the washing machine 1.

  Connected to the bottom of the washing tub 2 is a drain pipe 5 that discharges the water in the washing tub 2 or water containing a detergent to the outside of the washing machine 1. Furthermore, a drain valve 9 that opens and closes the flow path of the drain pipe 5 is installed in the drain pipe 5 inside the washing machine 1.

  The rotary drum 3, the feed water pressure adjusting valve 7, the feed water valve 8, the drain valve 9 and the exhaust valve 10 are controlled by sending and receiving electrical signals with a control device (not shown).

  In the case of washing with the washing machine 1 of this embodiment, after the laundry is put into the washing tub 2, the laundry inlet is sealed with a lid, the drain valve 9 and the exhaust valve 10 are closed, and only the water supply valve 8 is opened. Keep it. In addition, after closing the laundry inlet and closing the drain valve 9 and the exhaust valve 10, gases other than air (ozone, chlorine, etc.) may be introduced into the washing tub 2. In the embodiment, such a gas is not introduced.

  Next, the tap or the water take-off valve of the water pipe is opened, and the tap water is introduced into the washing tub 2 through the water supply pipe 4. During the introduction of tap water, tap water at a predetermined feed water pressure (fixed value of gauge pressure 0.02 MPa (absolute pressure 0.12 MPa) or higher) is introduced by the feed water pressure adjusting valve 7 and the inside of the washing tub 2 is predetermined. The exhaust valve 10 is appropriately opened and closed so that the pressure becomes (a fixed value of gauge pressure 0.02 MPa (absolute pressure 0.12 MPa) or higher) and a predetermined amount of water. As a result, the gas (air) in the washing tub is pressure-dissolved in the water in the washing tub so that the total dissolved gas concentration in the water is 120% or more of the saturation solubility under atmospheric pressure.

  Thereafter, the water supply valve 8 is closed, and the rotating drum 3 is rotated or swung to mix the water phase and the gas phase in the washing tub 2. Thereby, dissolution of air into water is promoted in the washing tub 2.

  Subsequently, the rotation of the rotary drum 3 is temporarily stopped, only the exhaust valve 6 is opened, and the inside of the washing tub 2 is opened to atmospheric pressure. As a result, dissolved gas that is supersaturated in water (air containing oxygen and nitrogen as main components) is generated as fine bubbles inside the laundry fibers or on the surface of the laundry, and the bubbles lift and remove dirt. can do.

  After that, the laundry in the washing tub 1 is rotated again by the rotating drum 3 and washed.

  Although the washing process is performed by the above operation, the washing process and the operation are the same in the rinsing process.

  In the above description, the exhaust valve 6 is opened and the inside of the washing tub 2 is opened to atmospheric pressure in order to generate fine bubbles in water. However, in order to generate more fine bubbles, the exhaust valve 6 is closed. It is preferable that the inside of the washing tub 2 is depressurized to an atmospheric pressure or lower in the state where For this reason, the exhaust pipe 6 is preferably provided with a decompression device such as a vacuum pump or an executor for decompressing the inside of the washing tub 2 to an atmospheric pressure or lower (that is, a negative pressure).

In addition, in order to enhance the cleaning effect of the detergent, as shown in FIG. 1, the water softening device 11 for making tap water supplied to the washing tub 2 soft water having a hardness of 50 mg CaCO ₃ / l or less, and / or the tap water A desalinator 12 that converts water into desalted water having a conductivity of 100 μS / cm or less, more preferably a conductivity of 50 μS / cm or less, is preferably attached to the water supply pipe 4. However, even if the washing machine does not include such a water softening device or a desalination device, the problem of the present application is solved.

  As the water softening device, for example, a device for passing water through a packed bed of Na-type cation exchange resin (for example, Amberlite 120b manufactured by Rohm and Haas) can be applied. As the desalting apparatus, for example, an ion exchange resin, a reverse osmosis membrane, or an electrochemical deionized water production apparatus as disclosed in JP 2010-29753 A can be applied.

  The washing effect of the washing machine of the present invention was confirmed according to JIS C9811 “Performance measurement method for household electric washing machine”. Examples for this purpose will be shown below.

Example 1
a) Washing tub A cylindrical container with a capacity of 1.2 liters made of stainless steel and having an inner diameter of 100 mm was prepared as a washing tub. Two stainless steel pipes with an outer diameter of 3 mm are connected 6 cm apart in the circumferential direction near the center of the straight body of the washing tub, one stainless steel valve is arranged on each pipe, one is a water introduction valve, The other was a gas discharge valve. The water introduction valve is connected to a water tap through a pressure regulating valve (so-called pressure reducing valve) and a pipe provided with a pressure gauge downstream of the pressure regulating valve, and tap water is set in the washing tub with the pressure regulating valve. It was used as open when introduced at a pressure of. The gas discharge valve is opened as necessary when water is introduced into the washing tub so that air in the washing tub is appropriately discharged, and a predetermined washing water amount (600 ml) described later is introduced into the washing tub at the predetermined pressure. It was adjusted. The gas discharge valve was also used as open when the pressure in the washing tub was released to atmospheric pressure. The tap water used had a conductivity of 250 μS / cm and a hardness of 80 mg CaCO ₃ / l.

b) Laundry For the laundry used in this example, purchase one (5cm x 5cm) that is prepared and distributed by the Laundry Science Association of the contaminated cloth specified in JIS C9811 Annex 3. Used.

c) Laundry process Three contaminated cloths and a commercial detergent (Kao New Beads: standard usage 25g / 30 liters) were put into the washing tub so that it would be 1/3 of the standard usage for 600ml of water. Next, tap water with a water supply pressure of 0.02 MPa (gauge pressure) is introduced into the washing tub by the pressure adjusting valve so that the pressure in the washing tub is 0.02 MPa (absolute pressure 0.12 MPa) and the water volume is 600 ml. Then, the gas discharge valve was opened as appropriate, and water was poured into the washing tub while discharging air in the washing tub. The water introduction valve and the gas discharge valve were closed to close the washing tub, and the washing tub was attached to a shaker and shaken at 25 ° C. for 10 minutes. Next, shaking was stopped once, the gas discharge valve was opened, the pressure in the washing tub was set to atmospheric pressure, the gas discharge valve was closed again, and the mixture was shaken for another 5 minutes.

d) Rinsing step After the washing, the water in the washing tub was drained and 600 ml of tap water was introduced in the same manner as the washing step, and the pressure in the washing tub was set to a gauge pressure of 0.02 MPa (absolute pressure 0.12 MPa). Attach the washing tub to the shaker, shake at room temperature for 5 minutes, stop shaking once, open the gas discharge valve, set the pressure in the washing tub to atmospheric pressure, and then close the gas introduction / discharge valve again Shake for another 5 minutes. Shaking for 5 minutes in the pressurized state as described above and 5 minutes in the open atmosphere was performed again, and shaking for a total of 20 minutes was used as a rinsing step.

e) About the drying process The contaminated cloth was taken out of the washing tub and left to dry at room temperature for 4 hours, and then dried with an iron.

f) Evaluation of residual dirt Measure the surface reflectance at a wavelength of 535 nm using a surface reflectance measuring device U-3010 made by Hitachi and measure the residual dirt (%) using the following formula. The cleaning effect was evaluated by calculation.
Residual stain (%) = Reflection of contaminated fabric before test (%) − Reflectivity of contaminated fabric after test (%)
(Example 2)
Residual dirt was evaluated in the same manner as in Example 1 except that the pressure at the time of introducing tap water in the washing and rinsing steps was changed to a gauge pressure of 0.05 MPa (absolute pressure of 0.15 MPa).

(Example 3)
Example 3 was carried out in the same manner as in Example 1 except that the pressure at the time of introducing tap water in the washing and rinsing steps was changed to a gauge pressure of 0.10 MPa (absolute pressure of 0.20 MPa) to evaluate residual dirt. In this example, it was possible to inject about 600 ml of water into the washing tub with a gauge pressure of 0.10 MPa (absolute pressure of 0.20 MPa) without opening the gas discharge valve and adjusting the amount of water when introducing tap water. Due to the dissolution of air in water, the amount of water in this example exceeded about 20 ml over 600 ml, but this was a slight difference and was evaluated in the same manner as the other examples and comparative examples.

Example 4
Following the opening of the atmosphere in the washing and rinsing process, the ejector is connected to the gas discharge valve, and the pressure in the washing tub is set to a negative pressure of 600 mmHg. In Example 1, after the opening of the atmosphere performed at atmospheric pressure. Residual stains were evaluated in the same manner as in Example 1 except that washing and rinsing for 5 minutes were performed under reduced pressure.

(Example 5)
Following the air release in the washing and rinsing process, the ejector is connected to the gas discharge valve, and the pressure in the washing tub is set to a negative pressure of 100 mmHg. Residual dirt was evaluated in the same manner as in Example 1 except that washing and rinsing for 5 minutes were performed under reduced pressure.

(Example 6)
The water used in the washing and rinsing process is made by blending soft water obtained by passing tap water through a Na-type cation exchange resin and softening it, and tap water raw water, so that the hardness is 50 mg CaCO ₃ / l. The operation was performed in the same manner as in Example 1 to evaluate residual dirt, and Example 6 was obtained.

(Example 7)
The water used in the washing and rinsing process is blended with pure water obtained by desalting by passing tap water through an equal volume mixed layer of H-type cation exchange resin and OH-type anion exchange resin and tap water raw water Thus, except that the conductivity was set to 50 μS / cm, the residual dirt was evaluated in the same manner as in Example 1 to obtain Example 7.

(Comparative Example 1)
The same operation as in Example 1 was carried out except that the gas discharge valve was opened at the time of filling with tap water in the washing and rinsing process, and the pressurization by tap water pressure was not performed, and all the washing and rinsing processes were performed at atmospheric pressure. Residual dirt was evaluated and it was set as Comparative Example 1.

(Confirmation of dissolved gas concentration)
In Examples 1 to 7 and Comparative Example 1 described above, it was confirmed by the following procedure that the dissolved gas was adjusted according to Henry's law by pressure adjustment. Put only 600ml of tap water in the washing tub, connect an air cylinder to the gas discharge valve and adjust the pressure in the washing tub to gauge pressure 0.00 (atmospheric pressure), 0.02, 0.05, 0.10MPa (absolute pressure 0.10, 0.12, 0.15, 0.20) MPa), or the pressure in the washing tub is set to a negative pressure of 600 mm and 100 mmHg in the same manner as described in Examples 4 and 5. The washing tub was shaken with a shaker at 25 ° C. for 5 minutes, and then the dissolved oxygen concentration and the dissolved nitrogen concentration were measured with a 3625 type dissolved gas measuring device manufactured by Orbis Fair. The results are shown in Table 1. The dissolved oxygen concentration and the dissolved nitrogen concentration were proportional to the absolute pressure and obeyed Henry's law within a range of ± 10%.

The results of Examples 1 to 7 and Comparative Example 1 are shown in Table 2. Residual stain (%) showed the average value of the three soiled cloths.

DESCRIPTION OF SYMBOLS 1 Washing machine 2 Washing tub 3 Rotating drum 4 Water supply pipe 5 Drain pipe 6 Exhaust pipe 7 Water supply pressure adjustment valve 8 Water supply valve 9 Drain valve 10 Exhaust valve

Claims (14)

A washing machine with a sealable washing tub,
A water supply pipe that is connected to the water supply pipe and supplies the tap water flowing through the water supply pipe to the washing tub, a water supply valve that opens and closes the flow path of the water supply pipe, and is supplied into the washing tub through the water supply pipe. A water supply pressure adjusting valve for adjusting the pressure of the tap water, an exhaust pipe for exhausting the gas in the washing tub, an exhaust valve for opening and closing a flow path of the exhaust pipe, the water supply valve, and the water supply pressure adjusting valve, A control device for controlling the exhaust valve,
The control device introduces tap water into the washing tub by water supply pressure by opening the water supply valve in a state where the washing tub is sealed, and controls the water supply pressure adjusting valve and the exhaust valve. The washing machine is characterized in that the gas in the washing tub is dissolved in the water in the washing tub so that the total dissolved gas concentration in water is 120% or more of the saturation solubility under atmospheric pressure.   The control device introduces tap water into the washing tub by water supply pressure by opening the water supply valve in a state where the washing tub is sealed, and controls the water supply pressure adjusting valve and the exhaust valve. After dissolving the gas in the washing tub in the water in the washing tub so that the total dissolved gas concentration in water is 120% or more of the saturation solubility under atmospheric pressure, the water supply valve is closed, and the exhaust The washing machine according to claim 1, wherein a dissolved gas that is supersaturated in water in the washing tub is generated as fine bubbles by opening a valve to open the washing tub to atmospheric pressure. A pressure reducing means for reducing the pressure in the washing tub;
The said control apparatus accelerates | stimulates generation | occurrence | production of the said fine bubble by decompressing the inside of the said washing tub to below atmospheric pressure with the said pressure reduction means, after opening the inside of the said washing tub to atmospheric pressure. Item 3. A washing machine according to Item 2.   The said control apparatus decompresses the inside of the said washing tub with the said pressure reduction means, The dissolved gas density | concentration in the water in this washing tub is made into 80% or less of the saturation solubility under atmospheric pressure, It is characterized by the above-mentioned. Washing machine.   When the gas in the washing tub is dissolved in the water in the washing tub so that the total dissolved gas concentration in the water is 120% or more of the saturation solubility under atmospheric pressure, the washing tub is rotated or swung. The washing machine according to any one of claims 1 to 4, further comprising a mechanism for forming a turbulent flow with respect to the tap water introduced into the washing tub. The washing machine according to any one of claims 1 to 5, further comprising a water softening device that converts tap water introduced into the washing tub into soft water having a hardness of 50 mg CaCO ₃ / l or less.   The demineralizer which makes the tap water introduce | transduced in the said washing tub into the demineralized water of electrical conductivity 100microS / cm or less, More preferably, electrical conductivity 50microS / cm or less is further provided. The washing machine according to any one of claims. A washing method for washing laundry in a washing tub using tap water,
After the laundry is put into the washing tub, tap water is introduced into the washing tub by a water supply pressure in a state where the washing tub is sealed, and the tap water introduction pressure into the washing tub and the The pressure in the washing tub is controlled to dissolve the gas in the washing tub in the water in the washing tub so that the total dissolved gas concentration in the water becomes 120% or more of the saturation solubility under atmospheric pressure. How to wash.   After the gas in the washing tub is dissolved in the water in the washing tub, the dissolved gas that has become supersaturated in the water in the washing tub is released by releasing the inside of the washing tub to atmospheric pressure. The washing method according to claim 8, wherein fine bubbles are generated inside the fiber or on the surface of the laundry, and dirt is lifted and removed by the fine bubbles.   After releasing the inside of the washing tub to atmospheric pressure, the inside of the washing tub is further reduced to the atmospheric pressure or less, thereby promoting the generation of the fine bubbles and obtaining a stronger dirt removing effect. Item 10. The washing method according to Item 9.   The washing method according to claim 10, wherein the inside of the washing tub is decompressed so that the dissolved gas concentration in the water in the washing tub is 80% or less of the saturated solubility under atmospheric pressure.   The washing method according to any one of claims 8 to 11, wherein the amount of detergent used is 1/3 or less of the standard amount of use. The washing method according to any one of claims 8 to 12, wherein the tap water introduced into the washing tub is soft water having a hardness of 50 mg CaCO ₃ / l or less.   13. The tap water introduced into the washing tub is demineralized water having a conductivity of 100 μS / cm or less, more preferably a conductivity of 50 μS / cm or less. How to wash.

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