RU2390304C1 - Dishwashing machine - Google Patents

Abstract

FIELD: personal use articles.

SUBSTANCE: invention relates to household equipment and dishwashing machine. Dishwashing machine comprises the following: unit of water softening, in which ion-exchange resin is contained, unit of recovery, where recovery solution is retained for recovery of ion-exchange resin, valve for recovery, unit of water hardness detection and device of control providing for valve opening and closure for recovery. Recovery of ion-exchange resin from unit of water softening is detected by hardness of flushing water.

EFFECT: invention provides for recovery of ion-exchange resin for water softening in proper period of time and maintenance of required concentration of recovery solution in dishwashing machine, thus improving quality of washing.

22 cl, 10 dwg

Description

FIELD OF THE INVENTION

The present invention relates to a dishwasher, which provides for washing dishes by spraying washing water on food debris adhering to the dishes.

State of the art

A water softener designed to soften flushing water is installed in the dishwasher. A device for water softening includes a water softening unit in which there is an ion-exchange resin (ion exchanger) for removing and adsorbing heavy metals and metal ions, and a recovery unit that provides salt retention and improving water softening by reducing the ion-exchange resin.

SUMMARY OF THE INVENTION

Technical problem

However, if the ion exchange resin in which heavy metals and metal ions are adsorbed is not restored in time in the water softening device of the prior art, there will not be sufficient water softening, and thus the washing quality provided by the dishwasher, significantly worsens. In addition, the surface of the tank will be corroded by stains caused by heavy metals or metal ions, which are still contained in the wash water.

In addition, since the user cannot determine whether the amount of salt contained in the recovery container is sufficient, it is difficult to recover the ion exchange resin in due time. That is, it is difficult for the user to ensure the timely addition of salt to the recovery container.

Technical solution

In accordance with embodiments, a dishwasher and a method for controlling a dishwasher are designed that can restore the [performance] of a water softener to a proper period of time and maintain a proper concentration of the reducing solution.

In one embodiment, the dishwasher includes a water softener that holds the ion exchange resin, a recovery block that holds the recovery solution to restore the ion exchange resin from the water softener, a recovery valve that selectively directs the recovery solution from the recovery block to the block water softeners for the recovery of ion exchange resins from a water softener, a stiffness determination unit for determining stiffness washing water supplied and a control device providing the opening and closing the restoring valve in accordance with the hardness specified hardness detecting unit.

In another embodiment, the dishwasher includes a water softener that holds the ion exchange resin, a recovery block that holds the recovery solution to restore the ion exchange resin from the water softener, a recovery valve that selectively directs the recovery solution from the recovery block to the block water softener to restore the ion-exchange resin from the water softener, a hardness determination unit, which is installed at the outlet side softened water from the water softening unit to determine the hardness of the supplied wash water, and a control device for opening and closing the recovery valve in accordance with the hardness determined by the hardness determining unit.

In yet another embodiment, the dishwasher includes a water softening unit in which the ion exchange resin is held, a recovery unit in which the reducing solution for recovering the ion exchange resin from the water softening unit is held, a recovery valve providing selective direction of the reducing solution from the recovery unit to a water softener for recovering an ion exchange resin from a water softener; a first and second hardness determination unit, which respectively and a control device that provides opening and closing of the valve for restoration in accordance with the difference between the stiffness values determined by the first stiffness determination unit and the stiffness determined by the second are installed near the output side and the input side of the water softening unit stiffness determination unit.

In yet another embodiment, the method for controlling the dishwasher includes determining the hardness of the washing water discharged from the water softening unit, and adjusting the moments of supply of the reducing solution to the water softening unit when the determined hardness exceeds a predetermined value.

In yet a further embodiment, the method for controlling the dishwasher includes determining the hardness of the washing water at the inlet side and the output side of the water softening unit and adjusting the moments of supply of the reducing solution to the water softening unit in accordance with the difference in hardness values at the input side and the output side of the softening unit water.

Details of one or more embodiments are provided in the accompanying drawings and in the following description. Other features will be apparent from the description and drawings, and from the claims.

Preferred Effects

By using the dishwasher and the control method similar to those described above, the effect is achieved that the water softener can be restored for a suitable period and the proper concentration of the reducing solution in the dishwasher can be maintained.

Brief Description of the Drawings

Figure 1 is a perspective view of a dishwasher in accordance with one embodiment.

FIG. 2 is a perspective view of a sump, a water supply unit, and a water softener of FIG. 1.

FIG. 3 is a perspective view of a water softener provided in a dishwasher in accordance with a first embodiment.

4 is a block diagram of a control unit of a dishwasher in accordance with one embodiment.

5 is a flowchart illustrating a method for operating a dishwasher in accordance with a first embodiment.

6 is a perspective view of a water softener provided in a dishwasher in accordance with a second embodiment.

7 is a flowchart illustrating a method for controlling a dishwasher in accordance with a second embodiment.

Fig. 8 is a perspective view of a water softener provided in a dishwasher in accordance with a third embodiment.

9 is a block diagram of a control unit of a dishwasher in accordance with another embodiment.

10 is a flowchart illustrating a method for controlling a dishwasher in accordance with a third embodiment.

An embodiment of the invention

Reference will now be made to embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

A dishwasher according to a first embodiment is described below.

Figure 1 is a perspective view of a dishwasher in accordance with the first embodiment.

As shown in figure 1, the dishwasher includes a housing 10 that defines the appearance, and a tank 20, which is installed in the housing 10 for the formation of the washing chamber 21.

The control unit 150 is located above the housing 10. The control unit 150 includes a display 155 for displaying the current operating state, a sound generation unit 156, and an input unit 151. The control unit 150 will be described later.

The guides 40 are located on the inner opposite walls of the washing chamber 21. The upper and lower shelves slide along the guides 40 to ensure their entry into the washing chamber 21 and the output from the washing chamber 21.

The door 50 is located at the front of the washing chamber 21 with the possibility of its opening and closing. Here, the door 50 is pivotally attached to the lower part of the housing 10 to open and close the front of the washing chamber 21.

An exhaust device 51 having an exhaust fan (not shown) is mounted on the door 50. The exhaust device 51 removes moisture from the washing chamber 21 when the dishwasher performs a drying operation.

The spray nozzle 60 is connected to the reservoir 20. The spray nozzle 60 sprays water towards the shelves during rotation. The spray nozzle 60 is connected to the sump 110.

A sump 110 is located at the bottom of the tank 20. A filter 111, forming the lower surface of the tank 20, is located above the sump 110. Wash water is accumulated in the sump 110 and it filters out food residues contained in the wash water.

A water softener 120 is located on the bottom of the tank 20. A water softener 120 is open to impact at the bottom of the tank 20, so that the user can add reducing material to the water softener 120.

FIG. 2 is a perspective view of a sump, a water supply unit, and the water softener of FIG. 1, and FIG. 3 is a water softener provided in a dishwasher in accordance with a first embodiment.

As shown in FIGS. 2 and 3, the base 30 is located on the bottom of the reservoir 20. A sump 110 and a water softener 120 are located on the base 30.

A flushing pump 112, forcing the flushing water towards the spray nozzle 60, and a drainage pump 113, for draining the flushing water returned to the sump 110 to the outside, are connected to the sump 110. In FIG. 2, the sump is shown in a state when the filter is open .

A water softener 120 is located on the side of the sump 110. A water softener 120 includes a water softener 121 for softening the water, and a recovery unit that is formed on the side of the water softener, and a recovery unit 125 provided at the side of the softener. An ion exchange resin (not shown) for softening the wash water is contained in the softening unit 121, and the reducing material is contained in the recovery unit 125. In the description below, a reducing material that dissolves in the wash water in the reducing unit 125 will be called a reducing solution.

A water supply unit 130 is located at the side of the sump 110. A water supply unit 130 may be located between the side wall of the reservoir 20 and the side wall of the housing 10.

A drain channel 131 is formed on a part of the water supply unit 130. A drain hose and a drain pump 113 are connected to opposite ends of the drain channel 131. A device (not shown) for preventing natural drainage, designed to prevent the natural drainage of water, is made in the drain channel, thereby preventing the natural drainage of water other than in the drain cycle.

A water supply unit 130 is provided with a flush water inlet 132 through which flush water is introduced externally. A flow meter 133 for determining a flow rate of water for rinsing water introduced externally is located adjacent to the rinsing water inlet 132.

A water supply unit 130 is provided with a chamber 134 in communication with the flush water inlet 132. The chamber 134 serves to temporarily hold a portion of the wash water introduced into the wash water inlet 132.

A communication hole 135 communicating with the reservoir 20 is formed at the top of the chamber 134. In addition, a connecting member 136 for connecting to the water softener and connected to the water softening device 121 is formed at the bottom of the chamber 134. The connecting element 137, intended to be connected to the recovery unit and connected to the recovery unit 125, is also formed at the bottom of the chamber 134. In this case, an opening / shut-off valve (not shown) can be installed on each connection tional element of the connecting member 136 for connecting with the water softening unit, and a connecting member 137 for connecting a recovery unit.

In addition, a water softening unit 121 is provided with an inlet element 122 of a water softening unit to which a connecting element 136 is connected to be connected to the water softening unit. An outlet element 123 of a water softener, through which softened flushing water is discharged from the water softener 121 to a sump, is formed on the upper part of the water softener 121. The water softener 121 and the recovery unit 125 communicate with each other when the recovery valve 127 is open.

The stiffness determination unit 140 for determining the stiffness of the wash water may be located on the upstream side of the water softener. For example, the stiffness determination unit 140 may be located on the chamber 134 or, although not shown in the drawings, on the inlet element 122 of the water softener. As a stiffness determining unit 140, a stiffness sensor can be used that measures the stiffness of the wash water by determining the magnitude of the current or voltage, which varies according to the amount of metal ions contained in the wash water.

The flushing water introduced through the flushing water inlet 132 is partially supplied to the reservoir 20 through the communication hole 135, partially supplied to the water softener 121 through a connecting element 136 for connecting to the water softener, and partially supplied to the recovery block 125 through the connecting element 137, designed to connect with the recovery unit. In addition, when the recovery valve 127 is opened, the reducing solution from the recovery unit 125 is directed to the water softening unit 121. The reducing solution removes metal ions adsorbed in the ion exchange resin, resulting in the restoration of the ion exchange resin.

A lid 128 is mounted on the upper part of the recovery unit 125 so that the lid 128 is open for exposure from the upper part of the reservoir 20. Therefore, the user opens the lid 128 and adds a reducing material, such as salt, to the recovery unit 125.

4 is a control unit for a dishwasher in accordance with one embodiment.

As shown in FIG. 4, the control unit 150 includes a control device 152 for controlling the dishwasher. An input unit 151 is connected to the control device 152 so that the user can select a mode. In addition, the stiffness determination unit 140, which measures the hardness of the wash water, and the memory unit 153, which stores data on the amount of the recovery solution from the recovery unit 125, which corresponds to the measured stiffness value, are connected to the control device 152.

The control device 152 provides the opening and closing of the valve 127 for recovery in accordance with the stiffness determined by block 140 stiffness determination. For example, the control device 152 allows the valve 127 to be opened to recover when the stiffness determined by the stiffness determination unit 140 exceeds the control value.

A drive unit 154 for actuating the water supply valve, a display 155, a sound generation unit 156, and a recovery valve 127, actuated in accordance with a control signal from the control device 152, are connected to the control device 152.

The stiffness determination unit 140 determines the amount of current or voltage due to heavy metals or metal ions from the wash water, and transmits a corresponding signal to the control device 152. The control device 152 reads a quantity characterizing the amount of the reducing solution that corresponds to the stiffness determined by the stiffness determination unit 140 and transmits a corresponding signal to the drive unit 154. In this case, the drive unit 154 controls the degree of opening and the duration of the opening of the recovery valve 127 in accordance with the control a signal from the control device 152.

The following describes the operation of the above-described dishwasher.

When the user enters the washing mode through the input unit 151, the dishwasher selectively or sequentially performs a washing operation and a drying operation in accordance with a signal from the control device 152. In this case, the washing operation includes at least one of a preliminary washing operation, a main washing operation, and a heated washing operation. In the description below, the operations of pre-washing, main washing and washing with heating are called the washing operation.

When the washing operation begins, the water supply valve opens and, thus, the washing water is supplied to the chamber 134 through the washing water inlet 132 provided in the water supply unit 130.

The flushing water supplied through the flushing water inlet 132 is partially directed to the reservoir 20 through the communication port 135 and is accumulated in the sump 110. The flushing water supplied through the flushing water inlet 132 is partially sent to the water softener 121 through the connecting element 136, designed to be connected to the water softener, and partially sent to the recovery unit 125 through the connecting element 137, designed to connect to the recovery unit.

In this case, in the water softening unit 121, metal ions contained in the wash water are adsorbed by the ion exchange resin, and thus, the wash water softens. Softened wash water is sent to the sump 110 through the outlet 123 of the water softener. In this case, the volume of the ion-exchange resin increases with the adsorption of metal ions in it.

When it is determined by a flow meter 133 that a sufficient amount of flushing water has been supplied, the flushing pump 112 is driven. The flushing pump 112 pumps out the flushing water introduced into the sump 110 and forcing it towards the spray nozzle 60. The spray nozzle 60 sprayes the flushing water onto the shelves 41 and 42 while rotating, thereby washing the dishes. Wash water drops down to return it to the sump 110. In this case, the filter 111 of the sump 110 filters out food residues. The flush water returned to the sump 110 is again pumped to the spray nozzle 60 by the flush pump 112.

The washing operation is performed for a predetermined time, after which a drain cycle is performed. The washing operation and the drain cycle are repeated a predetermined number of times, after which the drying operation is performed.

When the drying operation is performed, the heater (not shown) located in the tank 20 is driven. In addition, when actuating the exhaust device 51 provided on the door 50, moisture is removed to the outside. By performing the drying operation for a predetermined time specified in the control device 152, the dishes are dried.

Next, a method for controlling a dishwasher in accordance with a first embodiment will be described.

5 is a flowchart illustrating a method for operating a dishwasher in accordance with a first embodiment.

As shown in FIG. 5, when the washing operation begins, the water supply valve is open, and thus, the water supply unit 130 supplies the wash water (S11). In this case, the stiffness determination unit 140 determines the hardness of the wash water and transmits the corresponding information to the control device 152 (S12). The control device 152 determines the value of the quantity of supplied reducing solution, which corresponds to the stiffness determined by the stiffness determination unit 140.

In this case, the control device 152 provides the opening and closing of the valve 127 for recovery in accordance with the hardness of the wash water determined by the stiffness determination unit 140. For example, the control device 152 controls the recovery valve 127 so that the recovery valve 127 opens more often when the hardness of the wash water determined by the stiffness determining unit 140 increases.

As described above, since the amount of metal ions adsorbed by the ion exchange resin varies according to the hardness of the wash water, the opening time of the recovery valve 127 can be adjusted according to the number of metal ions adsorbed by the ion exchange resin. Therefore, the amount of reducing material, such as the salt used to reduce the ion exchange resin, can be reduced. In addition, by timely restoration of the performance of the water softener 121, stain corrosion caused by metal ions on the reservoir 20 and the sump 110 can be minimized.

In addition, the control device 152 can provide the opening of the valve 127 for recovery only in the drying operation. For example, the control device 152 determines whether a drying operation is performed (S14). When it is determined that the drying operation is not performed, the recovery valve 127 remains in its closed state. On the other hand, when it is determined that the drying operation is performed, the recovery valve 127 opens (S15). In this case, by controlling the recovery valve so that it will open to a predetermined extent during the predetermined opening time, the predetermined amount of the reducing solution contained in the recovery unit 125 will be sent to the water softening unit 121. In this case, the ion exchange resin in the water softening unit 121 is restored by means of a reducing solution.

The control device 152 determines whether a point in time for completion of recovery has been reached (S16). When it is determined that the recovery completion time has been reached, the recovery valve 127 closes (S17).

Next will be described a device for softening water in accordance with the second embodiment.

6 is a perspective view of a water softener in accordance with a second embodiment.

The water softener 120 of the second embodiment is substantially identical to the water softener of the first embodiment except for the location of the stiffness determining unit. Therefore, in the first and second embodiments, like reference numerals refer to like elements. A description of similar elements will be omitted in this second embodiment.

As shown in FIG. 6, the water softener 120 includes a hardness determination unit located on an output side of the water softener 121. A stiffness determination unit 240 located on the output side of the water softener 121 is connected to a control device 152. Therefore, block 240 determines the hardness of the wash water discharged through the discharge element of the water softener 121, and transmits the corresponding information to the control device 152.

In addition, the control device 152 enables the opening and closing of the valve 127 for recovery in accordance with the stiffness determined by the stiffness determination unit 240. For example, when the stiffness determined by the stiffness determination unit 240 is greater than the reference value, the control device 152 can provide the opening of the valve 127 for recovery. That is, since the hardness of the wash water discharged from the water softener 121 decreases when the ability of the water softener 121 to adsorb metal ions increases, there is no need to restore the ion exchange resin from the water softener 121 when the hardness of the wash water discharged from the softener 121 water will be less than the control value.

The following describes a method for controlling a dishwasher in accordance with a second embodiment.

7 is a flowchart illustrating a method for controlling a dishwasher in accordance with a second embodiment.

As shown in FIG. 7, when the washing operation begins, the water supply valve is open, and thus, the water supply unit 130 supplies the wash water (S21). The flushing water from the water supply unit 130 is partially supplied to the reservoir 20 through the communication hole 135 and partially supplied to the water softening unit 121 through a connecting element 136 for connecting to the water softening unit. Wash water from the water supply unit 130 may, if necessary, be partially supplied to the recovery unit 125 through a connecting element 137 for connecting to the recovery unit.

The flushing water supplied to the water softening unit 121 is softened by means of an ion exchange resin and introduced into the sump 110 through an outlet of the water softening unit 121. The stiffness determination unit 240 determines the hardness of the softened wash water and transmits the corresponding information to the control device 152 (S22). The control device 152 determines the amount of reducing solution to be supplied, in accordance with the information from the stiffness determination unit 240.

In this case, the control device 152 provides the opening and closing of the valve 127 for recovery in accordance with the hardness of the wash water determined by the stiffness determination unit 240. For example, the control device 152 controls the recovery valve 127 so that the recovery valve 127 opens more frequently when the hardness of the wash water determined by the stiffness determination unit 240 increases. In this case, if the washing water discharged from the softening unit 121 is sufficiently softened by means of an ion exchange resin, the hardness of the washing water will decrease, otherwise the hardness will be high.

As described above, since it can be determined that the adsorption capacity of the ion exchange resin from the water softener 121 decreases when the hardness of the flush water discharged from the water softener 121 increases, the opening time of the recovery valve 127 can be further reduced when the hardness of the wash the water discharged from the water softening unit 121 rises. Therefore, by timely restoration of the performance of the water softening unit 121, stain corrosion caused by metal ions on the reservoir 20 and the sump 110 can be minimized.

In addition, the control device 152 can provide the opening of the valve 127 for recovery only in the drying operation. For example, when it is determined by the control device 152 that the hardness of the wash water discharged from the water softener 121 exceeds a control value (S23), it is determined whether a drying operation is performed. When the control device 152 determines that the drying operation is not performed, the recovery valve 127 remains in its closed state. On the other hand, when it is determined that the drying operation is being performed, the recovery valve 127 is opened so that the reducing solution contained in the recovery unit 125 can be directed to the water softening unit 121 (S25). In this case, the ion exchange resin in the water softening unit 121 is restored by means of a reducing solution.

It is further determined whether the drying operation is completed (S26). When it is determined that the drying operation is completed, the recovery valve 127 closes (S27). Needless to say, it is also possible to control the recovery valve 127 in such a way that the recovery valve 127 will close after opening the recovery valve 127 for a predetermined period of time.

Next will be described a device for softening water in accordance with a third embodiment.

Fig. 8 is a perspective view of a water softener in accordance with a third embodiment.

The water softener 120 of the third embodiment is substantially identical to the water softener of the first embodiment except for the location and number of stiffness determining units. Therefore, in the first and third embodiments, like reference numerals refer to like elements. A description of similar elements will be omitted in this third embodiment.

As shown in FIG. 8, the water softener 120 includes a first hardness block 341 located on the output side of the water softener 121 and a second hardness block 342 located on the input side of the water softener 121.

9 is a control unit for a dishwasher in accordance with another embodiment.

As shown in FIG. 9, the first and second stiffness determination units 341 and 342 are connected to a control device. Therefore, the first hardness determination unit 341 determines the hardness of the wash water discharged from the water softener 121, and the second hardness determination unit 342 determines the hardness of the wash water introduced to the water softener 121. Information on the stiffness determined by the first and second stiffness determination units 341 and 342 is transmitted to the control device 152.

The control device 152 provides the opening and closing of the valve 127 for recovery in accordance with the difference in stiffness determined by the first stiffness determination unit 341 and stiffness determined by the second stiffness determination unit 342. For example, when the difference is less than the control value, the control device 152 opens the valve 127 for recovery. That is, since it can be considered that the wash water does not soften sufficiently in the water softener 121, when the difference is less than the reference value, the recovery valve 127 is opened to recover the ion exchange resin from the water softener 121.

The following describes a method for controlling a dishwasher in accordance with a third embodiment.

10 is a flowchart illustrating a method for controlling a dishwasher in accordance with a third embodiment.

As shown in FIG. 10, when the washing operation begins, the water supply valve is open, and thus, the water supply unit 130 supplies the wash water (S31). The flushing water from the water supply unit 130 is partially supplied to the reservoir 20 through the communication hole 135 and partially supplied to the water softening unit 121 through a connecting element 136 for connecting to the water softening unit.

In addition, the wash water from the water supply unit 130 may, if necessary, be partially supplied to the recovery unit 125 through a connecting element 137 for connecting to the recovery unit.

In this case, the second block 342 determines the hardness of the wash water introduced into the water softener 121 through the inlet element of the water softener 121 (S32). The second stiffness determination unit 342 transmits information on the determined stiffness to the control device 152.

The wash water in the water softener 121 is softened by means of an ion exchange resin and is sent to the sump 110 through the outlet of the water softener 121. In this case, the first hardness determination unit 341 determines the hardness of the softened wash water discharged from the water softener 121 and transmits the corresponding information to the control device 152 (S32).

When water is supplied for a predetermined period of time or to a predetermined water level, the water supply valve closes (S33).

The control device 152 compares the difference between the stiffness determined by the first stiffness determination unit 341 and the stiffness determined by the second stiffness determination unit 342 with a reference value (S34). When the difference is less than the control value, it will be determined that there is no need to supply a reducing solution to the water softening unit 121, since a small amount of metal ions is adsorbed in the ion exchange resin.

When the difference is greater than the control value, it will be determined that the amount of the reducing solution in the recovery unit 125 is insufficient. In this case, the control device 152 displays a message allowing the user to know that there is a need to add a reducing solution through the display 155 and / or the sound generation unit (S35).

The control device 152 provides the opening and closing of the valve 127 for restoring in accordance with the difference of the stiffness values determined by the first and second stiffness determination units 341 and 342. For example, the control device 152 controls the recovery valve 127 so that the recovery valve 127 opens more frequently when the difference in hardness of the incoming wash water and the hardness of the output wash water increases.

As described above, when the difference between the hardness of the incoming wash water and the hardness of the output wash water increases, it can be considered that the ability of the ion exchange resin to adsorb ions is insufficient. Therefore, the opening time of the recovery valve 127 can be extended. Therefore, by timely restoration of the performance of the water softening unit 121, stain corrosion caused by metal ions on the reservoir 20 and the sump 110 can be minimized.

In addition, the control device 152 can provide the opening of the valve 127 for recovery only in the drying operation. For example, when the control device 152 determines that the difference in stiffness exceeds a control value, the control device 152 determines whether a drying operation is performed (S36). When it is determined that the drying operation is performed, the recovery valve 127 is opened to direct the recovery solution from the recovery unit 125 to the water softening unit 121 (S37). When it is determined that the recovery of the ion exchange resin from the water softener 121 is completed (S38), the recovery valve 127 closes (S39).

Although embodiments have been described with reference to a number of illustrative embodiments, it should be understood that numerous other modifications and embodiments can be made by those skilled in the art that fall within the spirit and scope of the principles of this invention. More specifically, various variations and modifications are possible in the components and / or arrangements of the combined structure in question within the scope of the invention, the drawings and the appended claims. In addition to variations and modifications of components and / or arrangements for those skilled in the art, alternative applications will also be apparent.

Industrial applicability

By using the dishwasher and the control method in accordance with an embodiment of the present invention, it is possible to provide an effect that the performance of the water softening device can be restored within an appropriate period of time, and the proper concentration of the reducing solution can be maintained in the dishwasher, and industrial applicability is very substantial.

Claims (22)

1. Dishwasher containing:
a water softener that contains an ion exchange resin;
a recovery unit that contains a reducing solution for recovering an ion exchange resin from a water softener;
a recovery valve selectively guiding the reducing solution from the recovery unit to the water softener to recover the ion exchange resin from the water softener;
a stiffness determining unit for determining a stiffness of the supplied wash water; and
a control device providing opening and closing of the valve for recovery in accordance with the stiffness determined by the stiffness determination unit. 2. The dishwasher according to claim 1, in which the stiffness determination unit is located on the inlet side of the water softener. 3. The dishwasher of claim 1, wherein the control device opens a valve for recovery during the drying operation. 4. Dishwasher containing:
a water softener that contains an ion exchange resin;
a recovery unit that contains a reducing solution for recovering an ion exchange resin from a water softener;
a recovery valve selectively guiding the reducing solution from the recovery unit to the water softener to recover the ion exchange resin from the water softener;
a stiffness determination unit, which is located on the outlet side of the softened water from the water softener to determine the stiffness of the supplied wash water; and
a control device that opens and closes a valve for recovery in accordance with the stiffness determined by the stiffness determination unit. 5. The dishwasher according to claim 4, in which the control device opens the valve for recovery when the stiffness determined by the stiffness determination unit exceeds a predetermined value. 6. Dishwasher according to claim 4, in which the valve for recovery is open during the drying operation. 7. The dishwasher according to claim 4, further comprising a sound generation unit that allows the user to know that the amount of the reducing solution in the water softening unit is insufficient when the stiffness determined by the stiffness determination unit exceeds a control value. 8. The dishwasher according to claim 4, in which the control device provides a change in the amount of reducing solution supplied to the water softener, in accordance with the difference between the determined hardness and the control value. 9. Dishwasher containing:
a water softener that contains an ion exchange resin;
a recovery unit that contains a reducing solution for recovering an ion exchange resin from a water softener;
a recovery valve selectively guiding the reducing solution from the recovery unit to the water softener to recover the ion exchange resin from the water softener;
the first and second blocks of determining the stiffness, which are respectively installed on the output and input side of the water softener to determine the hardness of the supplied and discharged wash water; and
a control device that opens and closes valves for restoring in accordance with the difference between the stiffness value determined by the first stiffness determination unit and the stiffness determined by the second stiffness determination unit. 10. The dishwasher according to claim 9, in which the control device opens the valve for recovery when the difference between the stiffness values is less than the control value. 11. The dishwasher of claim 9, wherein the recovery valve is open during the drying operation. 12. The dishwasher according to claim 9, further comprising a sound generation unit that allows the user to know that the amount of the reducing solution in the water softening unit is insufficient when the difference between the hardness values is less than the control value. 13. The dishwasher according to claim 9, in which the amount of reducing solution supplied to the water softener is determined in accordance with the difference between the hardness values. 14. The dishwasher according to claim 9, further comprising a water supply unit for supplying washing water to the recovery unit, wherein a second stiffness determination unit is located on the water supply unit. 15. The control method of the dishwasher, according to which determine the rigidity of the wash water discharged from the water softener; and
adjust the time of supply of the reducing solution to the water softener when the determined hardness exceeds a predetermined value. 16. The method according to clause 15, according to which, when adjusting the time, a reducing solution is supplied from the recovery unit to the water softening unit when the determined hardness exceeds the control value. 17. The method according to clause 15, according to which additionally inform the user that the amount of the reducing solution in the water softener is insufficient when the determined hardness exceeds the control value. 18. The method according to clause 15, according to which the reducing solution from the recovery unit is supplied to the water softening unit for drying operations. 19. The method of controlling a dishwasher, according to which
determine the rigidity of the wash water at the inlet side and the outlet side of the water softener and
regulate the time of supply of the reducing solution to the water softening unit in accordance with the difference of the stiffness values on the input side of the water softening unit. 20. The method according to claim 19, according to which, when adjusting the time, a reducing solution is supplied from the recovery unit to the water softening unit when the difference in hardness values is less than a predetermined value. 21. The method according to claim 19, according to which the user is further informed that the amount of the reducing solution in the water softener is insufficient when the difference in hardness values exceeds the control value. 22. The method according to claim 19, according to which the reducing solution from the recovery unit is supplied to the water softening unit for drying operations.

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