Dish washer and control method thereof

Abstract

 A dishwasher includes a washing tub accommodating a detergent containing a first enzyme activated at an active temperature range and a second enzyme activated at another active temperature range differing from the active temperature range of the first enzyme, and wash water in which the detergent is dissolved, a heating unit heating wash water, and a controller controls driving of the heating unit such that the temperature of wash water is maintained within the active temperature range of the first enzyme for a first designated time, and controls driving of the heating unit such that the temperature of wash water is maintained within the active temperature range of the second enzyme for a second designated time, when the first designated time has elapsed.

Description

[0001] The present invention relates to a dishwasher which improves cleaning effects on tableware and a control method thereof.

[0002] In general, a dishwasher is an apparatus which removes contaminants (food waste) from tableware by jetting wash water, i.e., cold water or warm water, to the tableware at a high pressure.

[0003] The dishwasher includes a washing tub in which washing of tableware is executed, a plurality of baskets provided in a multi-stage structure within the washing tub and accommodating tableware, jet nozzles provided above and below the plurality of baskets and jetting wash water, and a pump connected to the jet nozzles and pumping wash water to the jet nozzles.

[0004] The dishwasher having the above configuration, when tableware to be washed is accommodated in the baskets, supplies wash water to the inside of the washing tub, operates the pump in a sump to supply wash water to the jet nozzles, and then jets wash water to the tableware through the jet nozzles, thereby washing the tableware using jet pressure of wash water.

[0005] A washing operation and a rinsing operation of such a dishwasher are repeated four times to six times according to the selected course, and the temperature of wash water or the jet time of wash water at each operation is determined according to the selected course.

[0006] In the dishwasher, the washing operation of the tableware is executed using a temperature profile which heats wash water to the maximum temperature when the washing operation is started, and stops heating of wash water when the temperature of wash water reaches the maximum temperature.

[0007] However, if tableware is washed using such a temperature profile, an active temperature of a contaminant decomposition enzyme contained in a detergent for washing tableware and a temperature of wash water set in the dishwasher, i.e., the maximum temperature, are different, and thus the dishwasher washes the tableware under the condition that the detergent is not activated during washing of the tableware. Thereby, tableware cleaning efficiency of the dishwasher may be lowered.

[0008] Further, since the temperature profile for washing tableware does not have a temperature maintenance time of wash water, the activation state of the detergent is not maintained as well as the detergent is not activated in an activation section of the detergent, and thus the dishwasher washes the tableware under the condition that features of the enzyme contained in the detergent are not used during washing of the tableware. Thereby, the dishwasher may exhibit cleaning performance lower than the contaminant decomposing and cleaning capacity of the detergent.

[0009] Therefore, it is an aspect of the present invention to provide a dishwasher which controls the temperature of wash water and the temperature maintenance time of wash water based on the active temperature of an enzyme contained in a detergent, and a control method thereof.

[0010] It is another aspect of the present invention to provide a dishwasher which controls the temperature of wash water step by step based on the active temperature of an enzyme contained in a detergent, and a control method thereof.

[0011] It is a further aspect of the present invention to provide a dishwasher which controls the amount of wash water jetted based on the temperature of wash water, and a control method thereof.

[0012] Additional aspects of the invention will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the invention.

[0013] In accordance with one aspect of the present invention, a dishwasher includes a washing tub accommodating a detergent containing a first enzyme activated at an active temperature range and a second enzyme activated at another active temperature range differing from the active temperature range of the first enzyme, and wash water in which the detergent is dissolved, a heating unit heating wash water, and a controller controls driving of the heating unit such that the temperature of wash water is maintained within the active temperature range of the first enzyme for a first designated time, and controls driving of the heating unit such that the temperature of wash water is maintained within the active temperature range of the second enzyme for a second designated time, when the first designated time has elapsed.

[0014] The first enzyme may be α-amylase, and the second enzyme may be protease. The dishwasher may further include a temperature detection unit detecting the temperature of wash water, and the controller may control driving of the heating unit based on the detected temperature of wash water.

[0015] The active temperature range of the first enzyme may be 32°C to 38°C, and the active temperature range of the second enzyme may be 45°C to 55°C.

[0016] The controller may control driving of the heating unit such that the temperature of wash water is raised step by step within the active temperature range of the first enzyme.

[0017] The active temperature range of the first enzyme may include a first maintenance temperature range and a second maintenance temperature range higher than the first maintenance temperature range, and the controller may control driving of the heating unit such that the temperature of wash water is maintained within the first maintenance temperature range for a first maintenance time, and control driving of the heating unit such that the temperature of wash water is maintained within the second maintenance temperature range for a second maintenance time.

[0018] The dishwasher may further include a sump provided within the washing tub, a circulation unit circulating wash water in the sump and a nozzle unit jetting wash water supplied from the circulation unit, and the controller may control driving of the circulation unit for the first designated time such that wash water maintained within the active temperature range of the first enzyme is circulated and jetted, and control driving of the circulation unit for the second designated time such that wash water maintained within the active temperature range of the second enzyme is circulated and jetted.

[0019] The dishwasher may further include a first basket, a second basket provided above the first basket and a cutlery basket provided above the second basket, and the nozzle unit may include a first nozzle provided below the first basket, a second nozzle provided between the first basket and the second basket, and a third nozzle provided above the cutlery basket.

[0020] The dishwasher may further include a first valve blocking wash water supplied to the first nozzle, a second valve blocking wash water supplied to the second nozzle and a third valve blocking wash water supplied to the third nozzle, and the controller may control opening and closing of the first, second and third valves such that the amount of wash water jetted through the first nozzle is greater than the amount of wash water jetted through the second and third nozzles during control for the first designated time. The controller may control opening and closing of the second and third valves such that the amount of wash water jetted through the second nozzle is greater than the amount of wash water jetted through the third nozzle.

[0021] The controller may control at least one of opening degrees, opening times and the numbers of opening frequencies of the first, second and third valves.

[0022] The controller may control opening and closing of the first, second and third valves such that the amount of wash water jetted through the second nozzle is greater than the amount of wash water jetted through the first and third nozzles during control for the second designated time.

[0023] The controller may control opening and closing of the first and third valves such that the amount of wash water jetted through the third nozzle is greater than the amount of wash water jetted through the first nozzle.

[0024] In accordance with another aspect of the present invention, a dishwasher includes a heating unit heating wash water in which a detergent containing a first enzyme activated at an active temperature range and a second enzyme activated at another active temperature range differing from the active temperature range of the first enzyme is dissolved, a circulation unit circulating wash water, a nozzle unit jetting wash water, and a controller controls driving of the heating unit to heat wash water, stops driving of the heating unit and controls driving of the circulation unit and the nozzle unit for a first designated time to circulate and jet wash water if the temperature of heated wash water is within the active temperature range of the first enzyme, controls driving of the heating unit to reheat wash water when the first designated time has elapsed, and stops driving of the heating unit and controls driving of the circulation unit and the nozzle unit for a second designated time to circulate and jet wash water if the temperature of reheated wash water is within the active temperature range of the second enzyme.

[0025] The first enzyme may be α-amylase, and the second enzyme may be protease. The controller may control driving of the heating unit such that the temperature of wash water is raised step by step within the active temperature range of the first enzyme.

[0026] The active temperature range of the first enzyme may include a first maintenance temperature range and a second maintenance temperature range higher than the first maintenance temperature range, and the controller may control driving of the heating unit such that the temperature of wash water is maintained within the first maintenance temperature range for a first maintenance time and control driving of the heating unit such that the temperature of wash water is maintained within the second maintenance temperature range for a second maintenance time.

[0027] The first maintenance time may be longer than the second maintenance time.

[0028] The dishwasher may further include a first basket, a second basket provided above the first basket and a cutlery basket provided above the second basket, and the nozzle unit may include a first nozzle provided below the first basket, a second nozzle provided between the first basket and the second basket, and a third nozzle provided above the cutlery basket.

[0029] The dishwasher may further include a first valve blocking wash water supplied to the first nozzle, a second valve blocking wash water supplied to the second nozzle and a third valve blocking wash water supplied to the third nozzle, and the controller may control opening and closing of the first, second and third valves such that the amount of wash water jetted through the first nozzle is greater than the amount of wash water jetted through the second and third nozzles during control for the first designated time. The dishwasher may further include a temperature detection unit detecting the temperature of wash water, and the controller may control opening of the first, second and third valves such that wash water is jetted through the first, second and third nozzles if the detected temperature of wash water is not within the active temperature range of the first second enzyme.

[0030] The dishwasher may further include a temperature detection unit detecting the temperature of wash water, and the controller may control opening of the second valve such that wash water is jetted through the second nozzle if the detected temperature of wash water is not within the active temperature range of the first enzyme.

[0031] The dishwasher may further include a temperature detection unit detecting the temperature of wash water, and the controller may control opening and closing of the first, second and third valves such that a first jet pattern of jetting wash water through the first, second and third nozzles and a second jet pattern of jetting wash water through the first nozzle are alternately executed if the detected temperature of wash water is within the active temperature range of the first enzyme.

[0032] The controller may simultaneously open the first, second and third valves during control using the first jet pattern.

[0033] The controller may alternately open the first, second and third valves in predetermined sequence during control using the first jet pattern.

[0034] The controller may control driving of the heating unit such that the temperature of wash water is raised by a designated temperature when the first designated time has elapsed.

[0035] The controller may control driving of the heating unit such that the raised temperature of wash water is maintained for a predetermined time.

[0036] In accordance with a further aspect of the present invention, a control method of a dishwasher which has a washing tub and a heating unit heating wash water in the washing tub, includes heating, circulating and jetting wash water in which a detergent is dissolved, when water is supplied to the washing tub, detecting the temperature of wash water in the washing tub, judging whether or not the detected temperature of wash water is within an active temperature range of a first enzyme contained in the detergent, circulating and jetting wash water within the active temperature range of the first enzyme for a first designated time while maintaining the temperature of wash water within the active temperature range of the first enzyme, upon judging that the detected temperature of wash water is within the active temperature range of the first enzyme, reheating wash water when the first designated time has elapsed, detecting the temperature of reheated wash water in the washing tub, judging whether or not the detected temperature of reheated wash water is within an active temperature range of a second enzyme contained in the detergent, circulating and jetting wash water within the active temperature range of the second enzyme for a second designated time while maintaining the temperature of wash water within the active temperature range of the second enzyme, upon judging that the detected temperature of wash water is within the active temperature range of the second enzyme, and turning the heating unit off when the second designated time has elapsed.

[0037] The circulating and jetting of wash water within the active temperature range of the first enzyme for the first designated time while maintaining the temperature of wash water within the active temperature range of the first enzyme may include raising the temperature of wash water step by step within the active temperature range of the first enzyme.

[0038] The raising of the temperature of wash water step by step within the active temperature range of the first enzyme may include maintaining the temperature of wash water within a first maintenance temperature range for a first maintenance time and maintaining the temperature of wash water within a second maintenance temperature range for a second maintenance time by reheating wash water, when the first maintenance time has elapsed.

[0039] The circulating and jetting of wash water may include pumping wash water in the washing tub, and respectively controlling opening and closing of a first valve blocking wash water supplied to a first nozzle provided below a first basket, a second valve blocking wash water supplied to a second nozzle provided between the first basket and a second basket, and a third valve blocking wash water supplied to a third nozzle provided above a cutlery basket.

[0040] The circulating and jetting of wash water within the active temperature range of the first enzyme may include controlling opening and closing of the first, second and third valves such that the amount of wash water jetted through the first and second nozzles is greater than the amount of wash water jetted through the third nozzle.

[0041] The circulating and jetting of wash water within the active temperature range of the first enzyme may further include controlling opening and closing of the first and second valves such that the amount of wash water jetted through the first nozzle is greater than the amount of wash water jetted through the second nozzle.

[0042] The controlling of opening and closing of the first, second and third valves may include controlling at least one of opening degrees, opening times and the numbers of opening frequencies of the first, second and third valves.

[0043] The circulating and jetting of wash water within the active temperature range of the second enzyme may include controlling opening and closing of the first, second and third valves such that the amount of wash water jetted through the second and third nozzles is greater than the amount of wash water jetted through the first nozzle.

[0044] The circulating and jetting of wash water within the active temperature range of the second enzyme may further include controlling opening and closing of the second and third valves such that the amount of wash water jetted through the second nozzle is greater than the amount of wash water jetted through the third nozzle.

[0045] The control method may further include controlling opening of the first, second and third valves such that wash water is simultaneously jetted through the first, second and third nozzles, upon judging that the detected temperature of wash water is not within the active temperature range of the first enzyme.

[0046] The control method may further include controlling opening of the first, second and third valves such that wash water is alternately jetted through the first, second and third nozzles, upon judging that the detected temperature of wash water is not within the active temperature range of the first enzyme.

[0047] The control method may further include controlling opening of the second valve such that wash water is jetted through the second nozzle, upon judging that the detected temperature of wash water is not within the active temperature range of the first enzyme.

[0048] The circulating and jetting of wash water within the active temperature range of the first enzyme may include controlling opening and closing of the first, second and third valves such that a first jet pattern of jetting wash water through the first, second and third nozzles and a second jet pattern of jetting wash water through the first nozzle are alternately executed.

[0049] The controlling of opening and closing of the first, second and third valves using the first jet pattern may include simultaneously opening the first, second and third valves. The controlling of opening and closing of the first, second and third valves using the first jet pattern may include alternately opening the first, second and third valves in predetermined sequence.

[0050] These and/or other aspects of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a perspective view of a dishwasher in accordance with one embodiment of the present invention;

FIG. 2 is a longitudinal-sectional view illustrating the internal structure of the dishwasher in accordance with the embodiment of the present invention;

FIG. 3 is a control block diagram of the dishwasher in accordance with the embodiment of the present invention;

FIGS. 4 and 5 are graphs illustrating wash water temperature control of the dishwasher in accordance with the embodiment of the present invention;

FIG. 6 is a graph illustrating activity of an enzyme contained in detergent according to time and temperature in the dishwasher in accordance with the embodiment of the present invention

FIGS. 7A and 7B are flowcharts illustrating a control method of the dishwasher in accordance with the embodiment of the present invention;

FIGS. 8A, 8B and 8C are views exemplarily illustrating jet of wash water through nozzles provided in the dishwasher in accordance with the embodiment of the present invention;

FIG. 9 is a graph illustrating cleaning performance according to contaminants of tableware accommodated in the dishwasher in accordance with the embodiment of the present invention;

FIG. 10A is a graph illustrating cleaning performance according to the final temperature of wash water in the dishwasher in accordance with the embodiment of the present invention; and

FIG. 10B is a graph illustrating cleaning performance according to the active temperature range of a first enzyme, the final temperature, and change of a nozzle to jet wash water.

[0051] Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout.

[0052] FIG. 1 is a perspective view of a dishwasher in accordance with one embodiment of the present invention, and FIG. 2 is a longitudinal-sectional view illustrating the internal structure of the dishwasher in accordance with the embodiment of the present invention. The dishwasher 100 includes a main body 110, a door 120, a washing tub 130, a machinery chamber 140, first and second baskets 150 and 160, a cutlery basket 170, guide members 180, a user interface 190, and a washing assembly 200.

[0053] The dishwasher 100 includes the main body 110 forming the external appearance of the dishwasher 100 and provided with an opening on one surface thereof, the door 120 rotatably provided on the opening of the main body 110 to open and close the opening, the washing tub 130 formed by the main body 110 and opened and closed by the door 120, and the machinery chamber 140 formed by the main body 110 and spatially separated from the washing tub 130.

[0054] The dishwasher 100 further includes the first and second baskets 150 and 160 and the cutlery basket 170 separated from each other in the washing tub 130, sliding forward and backward and accommodating tableware, the guide members 180 provided in the washing tub 130 and respectively guiding the first and second baskets 150 and 160 and the cutlery basket 170, the user interface 190 provided on the main body 110 and manipulating and displaying operation information of the dishwasher 100, and the washing assembly 200 provided in the machinery chamber 140 and the washing tub 130 and executing washing, rinsing and drying operations of tableware.

[0055] With reference to FIG. 1, the first and second baskets 150 and 160 and the cutlery basket 170 provided in the washing tub 130 will be described in more detail.
The washing tub 130 accommodates the first and second baskets 150 and 160 and the cutlery basket 10 having holes of various sizes through which wash water jetted from a jet unit passes.

[0056] The first basket 150 is installed in the lower portion of the inside of the washing tub 130, as seen from the bottom surface of the washing tub 130, the second basket 160 is installed in the middle portion of the inside of the washing tub 130, and the cutlery basket 170 is installed in the upper portion of the inside of the washing tub 130.

[0057] Here, the first basket 150 accommodates various kinds of tableware, such as bowls, dishes and cookware, the second basket 150 accommodates cups, and the cutlery basket 170 accommodates forks, table knives, spoons, chopsticks, kitchen knives and dippers. Further, guide members (not shown) supporting the first and second baskets 150 and 160 and guiding the first and second baskets 150 and 160 to the inside/outside of the washing tub 130 according to the pushing/pulling direction of the first and second baskets 150 and 160 are installed in the washing tub 130, and the guide members 180 supporting the cutlery basket 170 and guiding the cutlery basket 170 to the inside/outside of the washing tub 130 according to the pushing/pulling direction of the cutlery basket 170 are installed in the washing tub 130.

[0058] In the washing tub 130, only the first and second baskets 150 and 160 may be installed without the cutlery basket 170, or a larger number of baskets may be installed. Further, the cutlery basket 170 may be disposed in the lowermost portion of the washing tub 130.

[0059] The user interface 190 receives operation information, such as various washing courses (for example, a standard course, a manual course, etc.) and addition of rinsing, through user's instructions, and displays operation information in progress.

[0060] Here, the washing courses include the standard course in which a washing operation of washing tableware by jetting wash water to the tableware, a rinsing operation of rinsing the tableware by jetting rinse water to the tableware, and a drying operation of drying the tableware having undergone the rinsing operation are sequentially executed, and the manual course in which the respective operations are arbitrarily executed according to user's circumstances.

[0061] Further, the washing operation and the rinsing operation include a water supply mode in which wash for washing or rinsing is supplied, a circulation mode in which wash water or rinse water is circulated, a heating mode in which wash water or rinse water is heated, and a drain mode in which wash water or rinse water is discharged to the outside.

[0062] With reference to FIG. 2, the washing assembly 200 will be described in more detail. The washing assembly 200 includes a water supply unit 210, a sump 220, a heating unit 230, a filter unit 240, a circulation unit 250, a nozzle unit 260, and a drain unit 270. The water supply unit 210 includes a water supply pipe 211 located between an external water supply source and the sump 220 and guiding water introduced from the outside to the sump 220, and a water supply valve 212 blocking introduction of water from the outside.

[0063] The sump 220 stores water introduced through the water supply pipe 211. Such water in which a detergent is dissolved serves as wash water, and wash water circulates through the washing tub 130, the sump 220, the circulation unit 250 and the nozzle unit 260.

[0064] That is, the sump 220 is connected to the circulation unit 250, supplies wash water to the circulation unit 250 during the washing operation, and, when wash water jetted to the inside of the washing tub 130 through the nozzle unit 260 is introduced into the sump 220, restores wash water and resupplies wash water to the circulation unit 250. Such a sump 220 is provided with a water level detection unit 281 detecting the level of wash water, and a temperature detection unit 282 detecting the temperature of wash water.

[0065] Further, a heat insulating member (not shown) preventing heat emission from wash water to maintain the temperature of wash water is provided around the sump 220. The heating unit 230 is located around the sump 220, and is operated to heat wash water in the sump 220 according to instructions from a controller 283.

[0066] The filter unit 240 filters out contaminants separated from tableware from wash water, and then discharges only wash water to the sump 220. That is, the filter unit 240 stores the contaminants separated from the tableware.

[0067] The circulation unit 250 is provided between the sump 220 and the nozzle unit 260, pumps wash water in the sump 220, and supplies wash water to the nozzle unit 260 through circulation pipes 252 to 255.

[0068] Such a circulation unit 250 includes a circulation pump 251 pumping wash water in the sump 220, the circulation pipes 252 and 255 guiding the pumped wash water to the nozzle unit 260, and valves 256, 257 and 258 provided on the circulation pipes 253 to 255 and adjusting circulation of the pumped wash water.

[0069] The circulation pipes 252 to 255 include a main pipe 252 guiding wash water discharged from the circulation pump 251, and first to third branch pipes 253, 254 and 255 branched from the main pipe 252 and guiding wash water to respective nozzles 261 to 263.

[0070] In more detail, the first branch pipe 253 branched from the main pipe 252 guides wash water to a first nozzle 261, the second branch pipe 254 branched from the main pipe 252 guides wash water to a second nozzle 262, and the third branch pipe 255 branched from the main pipe 252 guides wash water to a third nozzle 263.

[0071] A first valve 256 is located on the first branch pipe 253, a second valve 257 is located on the second branch pipe 254, and a third valve 258 is located on the third branch pipe 255.

[0072] The first valve 256 adjusts flow of wash water supplied to the first nozzle 261 according to instructions from the controller 283, the second valve 257 adjusts flow of wash water supplied to the second nozzle 262 according to instructions from the controller 283, and the third valve 258 adjusts flow of wash water supplied to the third nozzle 263 according to instructions from the controller 283.

[0073] The nozzle unit 260 jets wash water supplied through the circulation unit 250 toward various tableware accommodated on the first and second baskets 150 and 160 and the cutlery basket 170.

[0074] The nozzle unit 260 includes the first nozzle 261 provided below the first basket 150, the second nozzle 262 provided between the first basket 150 and the second basket 160, and the third nozzle 263 provided above the cutlery basket 170.

[0075] The nozzle unit 260 includes a first rotor 264 provided on the first nozzle 261 and rotated by the pressure of wash water supplied from the circulation unit 250, a second rotor 265 provided on the second nozzle 262 and rotated by the pressure of wash water supplied from the circulation unit 250, and a third rotor 266 provided on the third nozzle 264 and rotated by the pressure of wash water supplied from the circulation unit 250.

[0076] That is, when wash water is jetted, the first nozzle 261 is rotated by rotation of the first rotor 264, the second nozzle 262 is rotated by rotation of the second rotor 265, and the third nozzle 263 is rotated by rotation of the third rotor 266.

[0077] Here, the first nozzle 261 is provided with a plurality of jet holes formed on the upper surface thereof and jets wash water in the upward direction through the plural jet holes, the second nozzle 262 is provided with a plurality of jet holes formed on the upper and lower surfaces thereof and jets wash water in the upward and downward directions through the plural jet holes, and the third nozzle 263 is provided with a plurality of jet holes formed on the lower surface thereof and jets wash water in the downward direction through the plural jet holes.

[0078] That is, the first nozzle 261 receives wash water supplied through the first branch pipe 253, the second nozzle 262 receives wash water supplied through the second branch pipe 254, and the third nozzle 263 receives wash water supplied through the third branch pipe 255.

[0079] The drain unit 270 discharges wash water in the sump 220 to the outside. The drain unit 270 includes a drain pump 271 pumping wash water in the sump 220, and a drain pipe 272 guiding the pumped wash water to the outside. The drain unit 270 may further include a drain valve (not shown) adjusting discharge of wash water in the sump 220 to the outside.

[0080] FIG. 3 is a control block diagram of the dishwasher in accordance with the embodiment of the present invention. The dishwasher includes the water level detection unit 281, the temperature detection unit 282, the controller 283, and first, second and third driving units 284, 285 and 286.

[0081] The water level detection unit 281 detects the level of water supplied to the sump 220 or the washing tub 130.

[0082] The temperature detection unit 282 detects the temperature of wash water in the sump 220.

[0083] The controller 283 controls driving of the washing assembly 200 according to operation information input through the user interface 190, thus controlling the washing operation, the rinsing operation and the drying operation.

[0084] The controller 283 controls closing of the water supply valve 212 based on the water level detected through the water level detection unit 281 during the washing operation, and controls driving of the heating unit 230 and the circulation unit 250 based on the temperature detected through the temperature detection unit 282 so as to improve tableware cleaning efficiency.

[0085] In more detail, if the temperature of wash water is adjusted to a temperature T2 within an active temperature range of a first enzyme and a temperature T3 within an active temperature range of a second enzyme, the configuration of the controller 283 will be described below.

[0086] As shown in FIG. 4, the controller 283 controls driving of the heating unit 230 such that wash water in the sump 220 maintains the active temperature T2 of the first enzyme contained in a detergent for a first designated time (M2 to M3), and controls driving of the heating unit 230 such that wash water in the sump 220 maintains the active temperature T3 of the second enzyme contained in the detergent for a second designated time (M4 to M5) when the first designated time has elapsed.

[0087] Here, the first enzyme is α-amylase, the second enzyme is protease, the active temperature of the first enzyme is a temperature within the range of 32°C to 38°C, and the active temperature of the second enzyme is a temperature within the range of 45°C to 55°C.

[0088] The controller 283 may control driving of the heating unit 230 such that the temperature of wash water is raised step by step within the active temperature range of the first enzyme when the washing operation is executed using wash water within the active temperature range of the first enzyme.

[0089] The active temperature range of the first enzyme includes a first maintenance temperature range and a second maintenance temperature range, and, if the temperature of wash water is adjusted to the temperature T2 within the first maintenance temperature range and the temperature T3 within the second maintenance temperature range, the control operation of the controller 283 will be described below.

[0090] As shown in FIG. 5, the controller 283 controls driving of the heating unit 230 such that wash water maintains the first maintenance temperature T2 for a first maintenance time M2 to M3, controls driving of the heating unit 230 such that wash water maintains the second maintenance temperature T3 for a second maintenance time M4 to M5, and then controls driving of the heating unit 230 such that wash water maintains the active temperature T4 of the second enzyme for a second designated time M6 to M7. Here, the temperature within the first temperature maintenance range is lower than the temperature within the second temperature maintenance range, and the first maintenance time is longer than the second maintenance time. The reason for this will be described below with reference to FIG. 6.

[0091] As shown in FIG. 6, it is understood that, as the reaction temperature of an enzyme is raised from the maximum active temperature 20°C (■) to 30°C (*), 45°C (•), and 55°C (◆), the initial reaction rate of the enzyme is increased but relative activity of the enzyme is rapidly decreased. Therefore, it is understood that, when the temperature is suddenly raised, initial relative activity of the enzyme is instantaneously raised but the enzyme is ineffective in terms of maintenance of relative activity of the enzyme.

[0092] That is, as the temperature is higher, the initial reaction rate of the enzyme is increased but thermo stability of the enzyme is more rapidly reduced as time goes by, and thus relative activity of the enzyme is more rapidly reduced at a higher temperature. Thereby, when relative activity of the enzyme is reduced, the contaminant decomposing performance of the enzyme is reduced together and thus leads to reduction of cleaning performance.

[0093] Therefore, activity of α-amylase may be maximally used by gradually increasing the temperature of wash water and allowing maintenance time to be shorter at high temperature than at a low temperature.

[0094] Further, control of the driving of the heating unit 230 may be varied according to the heat insulating state of the sump 220 and the washing tub 130.

[0095] If the heat insulating state is good, the decrease rate of the temperature of wash water for the first designated time is small under the condition that the temperature of wash water is within the active temperature range of the first enzyme, and thus re-driving of the heating unit 230 for the first designated time is not required.

[0096] On the other hand, if the heat insulating state is not good, the decrease rate of the temperature of wash water for the first designated time is large under the condition that the temperature of wash water is within the active temperature range of the first enzyme, and thus cleaning effects may be lowered and re-driving of the heating unit 230 is required.

[0097] Therefore, if the heat insulating state is good, the controller 283 stops driving of the heating unit 230, when the temperature of wash water is within the active temperature range of the first enzyme.

[0098] Further, if the heat insulating state is not good, the controller 283 periodically detects the temperature of wash water such that wash water continuously maintains the active temperature range of the first enzyme, and controls driving of the heating unit 230 when the periodically detected temperature of wash water is lower than the active temperature range.

[0099] Here, control of the driving of the heating unit 230 is applied also, if the temperature of wash water is maintained within the active temperature range of the second enzyme for the second designated time.

[0100] Further, control of the heating unit 230 by the controller 283 is determined according to the heat insulating state when the dishwasher is manufactured, and is programmed. The controller 283 controls driving of the circulation unit 250 for the first designated time such that wash water maintained within the active temperature range of the first enzyme is circulated and jetted, and controls driving of the circulation unit 250 for the second designated time such that wash water maintained within the active temperature range of the second enzyme is circulated and jetted.

[0101] The controller 283 controls opening and closing of the first, second and third valves 256 such that the amount of wash water jetted through the first nozzle 261 from among the first, second and third nozzles 261, 262 and 263 is greatest during control of the circulation unit 250 for the first designated time.

[0102] That is, since tableware accommodated in the first basket 150 may be bowls having a strong possibility of being contaminated with contaminants, such as starch, the first nozzle 261 jets wash water in which α-amylase is activated to the first basket 150, thereby improving the cleaning performance to the tableware accommodated in the first basket 150.

[0103] Further, the controller 283 controls opening and closing of the first, second and third valves 256 such that the amount of wash water jetted through the second nozzle 262 from among the first, second and third nozzles 261, 262 and 263 is greatest during control of the circulation unit 250 for the second designated time.

[0104] That is, since tableware accommodated in the second basket 160 may be cups having a strong possibility of being contaminated with contaminants, for example a protein such as milk, the second nozzle 262 jets wash water in which protease is activated to the second basket 160, thereby improving the cleaning performance to the tableware accommodated in the second basket 160.

[0105] The controller 283 drives the circulation pump 251 and controls opening of the first, second and third valves 256, 257 and 258 such that wash water is jetted through the first, second and third nozzles 261, 262 and 263 when the detected temperature of wash water is not within the active temperature range of the first enzyme. Here, the controller 283 simultaneously opens and closes the first, second and third valves 256, 257 and 258, or alternately opens and closes the first, second and third valves 256, 257 and 258 in a predetermined sequence.

[0106] Further, when the first, second and third valves 256, 257 and 258 are alternately opened and closed, pairs of valves may be alternately opened and closed. For example, opening of the first and second valves 256 and 257, opening of the second and third valves 257 and 258, and opening of the third and first valves 258 and 256 may be sequentially carried out.

[0107] Further, the controller 283 may open only the second valve 257 such that washing water is jetted only through the second nozzle 262 when the detected temperature of wash water is not within the active temperature range of the first enzyme.

[0108] The controller 283 controls opening and closing of the first, second and third valves 256, 257 and 258 such that a first jet pattern of jetting wash water through the first, second and third nozzles 261, 262 and 263 and a second jet pattern of jetting wash water through the first nozzle 261 are alternately executed when the detected temperature of wash water is within the active temperature range of the first enzyme. During control of the first jet pattern, the controller 283 simultaneously opens the first, second and third valves 256, 257 and 258, or alternately opens the first, second and third valves 256, 257 and 258 in predetermined sequence.

[0109] The controller 283 is electrically connected to the user interface 190, and thus receives operation information for washing tableware through the user interface 190 and controls display of the operation information of the dishwasher.

[0110] The first driving unit 284 drives at least one of the water supply valve 211, the first valve 256, the second valve 257 and the third valve 258 according to a driving control signal from the controller 283.

[0111] The second driving unit 285 drives the heating unit 280 according to a driving control signal from the controller 283.

[0112] The third driving unit 286 drives at least one of the circulation pump 251 and the drain pump 271 according to a driving control signal from the controller 283.

[0113] FIGS. 7A and 7B are flowcharts illustrating a control method of the dishwasher in accordance with the embodiment of the present invention, and the control method of the dishwasher will be described with reference to FIGs. 1, 2, 3, 8A, 8B and 8C.

[0114] First, as shown in FIG. 7A, the dishwasher receives water supplied from the external water supply source by opening the water supply valve 212 of the water supply unit 210 (Operation 301).

[0115] Thereafter, the dishwasher stores water supplied through the water supply pipe 211 in the sump 220. A detergent is dissolved in water in the sump 220, and water containing the detergent serves as wash water.

[0116] The dishwasher detects the level of water in the sump 220 or the washing tub 130, compares the detected water level with a reference water level, and closes the water supply valve 212 when the detected water level is more than the reference water level. The dishwasher drives the heating unit 230 to heat wash water in the sump 220, drives the circulation pump 251 to pump wash water in the sump 220, and opens the first to third valves 256, 257 and 258 to jet wash water in the sump 220 to the first and second baskets 150 and 160 and the cutlery basket 170 in the washing tub 130 through the first, second and third nozzles 261, 262 and 263, thereby washing tableware accommodated in the first and second baskets 150 and 160 and the cutlery basket 170 (Operation 302). Here, opening of the first to third valves 256, 257 and 258 includes periodically opening and closing of the first to third valves 256, 257 and 258, as shown in FIG. 8C, and particularly includes simultaneously opening of the first to third valves 256, 257 and 258. Thereby, wash water is simultaneously jetted through the first, second and third nozzles 261, 262 and 263.

[0117] Further, opening of the first to third valves 256, 257 and 258 may include alternately opening of the first to third valves 256, 257 and 258 in predetermined sequence. Further, opening of the first to third valves 256, 257 and 258 may include opening of only the second valve 257 while closing of the first and third valves 256 and 258 so as to jet wash water only through the second nozzle 262.

[0118] Thereafter, the dishwasher detects the temperature of wash water through the temperature detection unit 282 (Operation 303), and judges whether or not the detected temperature of wash water is within the active temperature range of the first enzyme by comparing the detected temperature of wash water with the active temperature range of the first enzyme (Operation 304).

[0119] When the detected temperature of wash water is lower than the active temperature range of the first enzyme, i.e., when the temperature of wash water is not within the active temperature range of the first enzyme, jet of wash water through the first, second and third nozzles 261, 262 and 263 is maintained.

[0120] On the other hand, when the detected temperature of wash water is within the active temperature range of the first enzyme, the dishwasher stops driving of the heating unit 230 to stop heating of wash water (Operation 305), drives the circulation pump 251 for a first designated time to pump wash water in the sump 220 and controls opening and closing of the first, second and third valves 256, 257 and 258 to jet wash water to the first and second baskets 150 and 160 and the cutlery basket 170 in the washing tub 130 (Operation 306). Here, the first designated time is optimally 5 to 15 minutes, but may be adjusted to time more than or less than such time.

[0121] Here, the first and second valves 256 and 257 may be opened such that a large amount of wash water is jetted to the first basket 150 through the first nozzle 261 and the second nozzle 262, as shown in FIG. 8B.

[0122] Further, the first jet pattern of jetting wash water through the first, second and third nozzles 261, 262 and 263 and the second jet pattern of jetting wash water through the first nozzle 261 may be alternately executed.

[0123] Here, the first jet pattern is used to simultaneously open the first, second and third valves 256, 257 and 258, or to alternately open the first, second and third valves 256, 257 and 258 in predetermined sequence.

[0124] That is, this is to jet the greatest amount of wash water through the first nozzle 261 from among the first, second and third nozzles 261, 262 and 263.

[0125] The reason for this is that the amount of α-amylase in an active state contacting tableware is increased by increasing the amount of wash water jetted toward the first basket 150 in which tableware, such as bowls, is accommodated. Thereby, the cleaning performance to the tableware may be improved.

[0126] Further, the dishwasher may control opening and closing of the first, second and third valves 256, 257 and 258 such that the amount of wash water jetted through the first nozzle 261 is greater than the amount of wash water jetted through the second and third nozzles 262 and 263 during driving of the circulation unit 250 for the first designated time. Here, the dishwasher may control opening and closing of the second and third valves 257 and 258 such that the amount of wash water jetted through the second nozzle 262 is greater than the amount of wash water jetted through the third nozzle 263.

[0127] Control of opening and closing of the first, second and third valves 256, 257 and 258 includes control of at least one of opening degrees, opening times and the numbers of opening frequencies of the first, second and third valves 256, 257 and 258.

[0128] Further, the dishwasher may periodically detect the temperature of wash water such that wash water continuously is maintained within the active temperature range of the first enzyme, and drive the heating unit 230 when the periodically detected temperature of wash water is lower than the active temperature range of the first enzyme, during driving of the circulation unit 250 for the first designated time. Thereafter, the dishwasher judges whether or not the first designated time has elapsed (Operation 307), and, upon judging that the first designated time has elapsed, drives the heating unit 230 to reheat wash water, drives the circulation pump 251 to pump wash water in the sump 220, controls opening and closing of the first, second and third valves 256, 257 and 258 to supply wash water to the respective nozzles through the circulation pipes, thereby jetting wash water toward the first and second baskets 150 and 160 and the cutlery basket 170 in the washing tub 130.

[0129] Thereafter, the dishwasher detects the temperature of wash water reheated through the temperature detection unit 282 (Operation 308), and judges whether or not the temperature of reheated wash water is within the active temperature range of the second enzyme by comparing the temperature of reheated wash water with the active temperature range of the second enzyme (Operation 309).

[0130] Here, the first enzyme is α-amylase, the second enzyme is protease, the active temperature range of the first enzyme is 32 to 38°C, and the active temperature range of the second enzyme is 45°C to 55°C.

[0131] Thereafter, if the temperature of reheated wash water is lower than the active temperature range of the second enzyme, the dishwasher judges that the temperature of reheated wash water is not within the active temperature range of the first enzyme and maintains the process of pumping wash water through the circulation pump 251 and jetting wash water.

[0132] On the other hand, if the temperature of reheated wash water is within the active temperature range of the second enzyme, the dishwasher stops driving of the heating unit 230 to stop reheating of wash water (Operation 310), drives the circulation pump 251 to pump wash water in the sump 220, and controls opening and closing of the first, second and third valves 256, 257 and 258 to supply wash water to the respective nozzles, thereby jetting wash water to the first and second baskets 150 and 160 and the cutlery basket 170 in the washing tub 130 (Operation 311). That is, the circulation unit 250 is driven for the second designated time.

[0133] As shown in FIG. 8C, the amount of wash water jetted through the second and third nozzles is increased more than the amount of wash water jetted through the first nozzle such that a large amount of wash water is jetted to the second basket 160.

[0134] That is, at least one of the numbers of opening frequencies, opening degrees and opening times of the first, second and third valves 256, 257 and 258 are adjusted such that the amount of wash water jetted through the second and third nozzles 262 and 263 is greater than the amount of wash water jetted through the first nozzle 261.
Further, at least one of the numbers of opening frequencies, opening degrees and opening times of the second and third valves 257 and 258 may be adjusted such that the amount of wash water jetted through the second nozzle 262 is greater than the amount of wash water jetted through the third nozzle 263.

[0135] That is, this is to jet the greatest amount of wash water through the second nozzle 262 from among the first, second and third nozzles 261, 262 and 263. The reason for this is that the amount of protease in an active state contacting tableware is increased by increasing the amount of wash water jetted toward the second basket 160 in which tableware, such as cups, is accommodated. Thereby, the cleaning performance to the tableware may be improved.

[0136] Thereafter, the dishwasher judges whether or not the second designated time has elapsed (Operation 312), and, upon judging that the second designated time has elapsed, controls driving of the drain pump 271 to discharge wash water in the washing tub 130 and the sump 220 to the outside and terminates the washing operation.

[0137] Further, time required to increase the temperature of wash water to the active temperature range of the first enzyme and time required to increase the temperature of wash water to the active temperature range of the second enzyme may be respectively predetermined, without the temperature detection unit, and the heating unit 230 may be driven for the respective predetermined times.

[0138] Active temperatures to maximize activity of contaminant decomposing components, such as enzymes and a surface active agent contained in the detergent, and the most effective maintenance times set according to active features of the detergent are applied to a tableware washing profile, thereby maximizing contaminant decomposing performance of the enzymes and improving tableware cleaning performance.

[0139] Further, since tableware cleaning efficiency is improved as activity of the enzyme is maximized, the maximum temperature of wash water during washing of tableware may be lowered, and thus energy consumed during washing of tableware may be reduced. Further, since a position from wash water is jetted and the amount of wash water are adjusted according to the kind of enzyme, the contact amount of the enzyme decomposing a target contaminating component may be maximized based on the target contaminating component according to the kind of tableware, and thus tableware cleaning efficiency may be improved.

[0140] When wash water within the active temperature range of the first enzyme is pumped and jetted to wash tableware, the dish water may wash the tableware while raising the temperature of wash water step by step within the active temperature range of the first enzyme. This will be described with reference to FIG. 7B.

[0141] As shown in FIG. 7B, the dishwasher drives the heating unit 230 to heat wash water in the sump 220, drives the circulation pump 251 and opens the first to third valves 256, 257 and 258 to jet wash water in the sump 220 to the first and second baskets 150 and 160 and the cutlery basket 170 in the washing tub 130 through the first, second and third nozzles 261, 262 and 263.

[0142] Here, the dishwasher detects the temperature of wash water, and opens the first, second and third valves 256, 257 and 258 to jet wash water through the first, second and third nozzles 261, 262 and 263, if the temperature of wash water is not within the active temperature range of the first enzyme. The first, second and third valves 256, 257 and 258 are simultaneously opened and closed, or are alternately opened and closed in predetermined sequence.

[0143] Further, only the second valve 257 may be opened to jet wash water only through the second nozzle 262.

[0144] On the other hand, if the detected temperature of wash water is within the active temperature range of the first enzyme, the dishwasher judges whether or not the detected temperature of wash water is within the first maintenance temperature range from among the active temperature range of the first enzyme (Operation 306a).
Upon judging that the temperature of wash water is within the first maintenance temperature range, the dishwasher drives the circulation pump 251 for a first maintenance time to pump wash water in the sump 220, and controls opening of the first, second and third valves to jet pumped wash water through the first, second and third nozzles (Operation 306b).

[0145] Thereafter, the dishwasher judges whether or not the first maintenance time has elapsed (Operation 306c), and drives the heating unit 230 to reheat wash water and detect the temperature of reheated wash water, upon judging that the first maintenance time has elapsed (Operation 306d).

[0146] Thereafter, the dishwasher judges whether or not the detected temperature of wash water is within a second maintenance temperature range from among the active temperature range of the first enzyme by comparing the detected temperature of wash water with the second maintenance temperature range (Operation 306e).

[0147] Upon judging that the detected temperature of wash water is within the second maintenance temperature range, the dishwasher stops driving of the heating unit 230 to stop heating of wash water (Operation 306f), drives the circulation pump 251 for a second maintenance time to pump wash water in the sump 220, and controls opening of the first, second and third valves to jet pumped wash water through the first, second and third nozzles (Operation 306g).

[0148] The dishwasher executes control of the circulation unit 250 within the active temperature range of the first enzyme for the first and second maintenance times. That is, the dishwasher drives the circulation pump 251 to pump wash water in the sump 220, and controls opening of the first, second and third valves such that the amount of wash water jetted through the first nozzle 261 from among the first, second and third nozzles 261, 262 and 263 is greatest.

[0149] For example, the dishwasher increases the opening degree of the first valve more than the opening degrees of the second and third valves, increases the number of opening frequencies of the first valve more than the numbers of opening frequencies of the second and third valves, and increases the opening time of the first valve longer than the opening times of the second and third valves.

[0150] Thereafter, the dishwasher judges whether or not the second maintenance time has elapsed (Operation 306h), and drives the heating unit 230 to heat wash water to the active temperature range of the second enzyme, upon judging that the second maintenance time has elapsed.

[0151] While wash water is heated to the active temperature range of the second enzyme, the dishwasher executes control of the circulation unit 250 at an inactive temperature of the first enzyme. That is, the dishwasher drives the circulation pump 251 to pump wash water in the sump, and simultaneously or alternately opens the first, second and third valves to simultaneously or alternately jet pumped wash water through the first, second and third nozzles.

[0152] Here, the sum of the first maintenance time and the second maintenance time is the first designated time.

[0153] Further, during executing washing while raising the temperature of wash water step by step within the active temperature range of the first enzyme, the sum of the first maintenance time and the second maintenance time may be longer than the first designated time.

[0154] When the temperature of wash water is raised step by step within the active temperature range of the first enzyme in this way, component decomposition using the enzyme is promoted, thus improving cleaning performance.

[0155] In more detail, since the second maintenance temperature range is a temperature zone where exhibits maximum activity at an early stage but is rapidly reduced in activity due to lowered stability, if wash water is heated to the second maintenance temperature range without heating to the first maintenance temperature range, thermo stability of α-amylase is lowered and activity of α-amylase is not maintained for a long time and is rapidly reduced.

[0156] Thereby, after α-amylase absorbs sufficient energy within the first maintenance temperature range and is activated, α-amylase is immediately raised to a temperature within the second maintenance temperature range higher than the first maintenance temperature range so that activity of α-amylase is maximized without deformation. Thus, contaminant decomposing capacity of α-amylase may be maximally brought out until contaminant decomposing capacity of α-amylase disappears.

[0157] FIGS. 9, 10A and 10B are graphs illustrating cleaning performance when the temperature of wash water is adjusted to the active temperature range of the first enzyme.

[0158] FIG. 9 is a graph illustrating cleaning performances with respect to oatmeal, spinach and milk according to adjustment of the active temperature range of the first enzyme and the final temperature.

[0159] Prior art represents conventional cleaning performance, detergent activation 1 and detergent activation 2 represent cleaning performances when the temperature of wash water is maintained in one step within the active temperature range of the first enzyme, and 2 step detergent activation 1 and 2 step detergent activation 2 represent cleaning performances when the temperature of wash water is maintained in two steps within the active temperature range of the first enzyme.

[0160] The final temperatures of wash water at detergent activation 1 and 2 step detergent activation 1 are lower than the final temperatures of wash water at detergent activation 2 and 2 step detergent activation 2.

[0161] In each test, as a result of the cleaning performances with respect to oatmeal, spinach and milk, it is understood that cleaning performance when tableware is washed by activating an enzyme is higher than conventional cleaning performance.

[0162] Further, it is understood that cleaning performance at detergent activation 2 having the higher final temperature than at detergent activation 1 is higher and cleaning performance at 2 step detergent activation 2 having the higher final temperature than 2 step detergent activation 1 is higher, and it is understood that cleaning performance if the temperature of wash water is maintained in two steps within the active temperature range of the first enzyme is higher than cleaning performance if the temperature of wash water is maintained in one step within the active temperature range of the first enzyme.

[0163] FIG. 10A is a graph illustrating cleaning performance according to the final temperature of wash water. It is understood that, cleaning performance if tableware is washed under the condition that the enzyme is activated, is more excellent even in a state in which the final temperature of wash water is lower then conventional cleaning performance.

[0164] FIG. 10B is a graph illustrating cleaning performance according to the active temperature range of the first enzyme, the final temperature, and change of the nozzle to jet wash water.

[0165] Prior art represents conventional cleaning performance, detergent activations 1, 2, two step detergent activation 1 and two step detergent activation 2 represent cleaning performances when the temperature of wash water is maintained in one step within the active temperature range of the first enzyme, and 2 step detergent activation represents cleaning performances when the temperature of wash water is maintained in two steps within the active temperature range of the first enzyme.

[0166] Further, detergent activations 1, 2, two step detergent activation 1 and two step detergent activation 2 represent cleaning performances if the amounts of wash water jetted through the first, second and third nozzles are varied. Detergent activations 1 and two step detergent activation 1 represent cleaning performances if wash water is intensively jetted through the first nozzle, and detergent activations 2 and two step detergent activation 2 represent cleaning performances if wash water is intensively jetted through the third nozzle. Further, detergent activations 1 and 2 represent cleaning performances if wash water is jetted alternately through different nozzles. As shown in FIG. 10B, it is understood that, if the final temperature of wash water is set to 43°C, cleaning performance when tableware is washed under the condition that the temperature of wash water is maintained in one step within the active temperature range of the first enzyme is more excellent than conventional cleaning performance. Further, it is understood that, if the final temperature of wash water is set to 44°C, cleaning performance when tableware is washed under the condition that the temperature of wash water is maintained in one step or two steps within the active temperature range of the first enzyme is more excellent than conventional cleaning performance.

[0167] Here, it is understood that cleaning performance when tableware is washed under the condition that the temperature of wash water is maintained in two steps within the active temperature range of the first enzyme is most excellent.

[0168] Further, it is understood that, if the final temperature of wash water is set to 50°C, cleaning performance when tableware is washed under the condition that the temperature of wash water is maintained in one step or two steps within the active temperature range of the first enzyme is more excellent than conventional cleaning performance.

[0169] Here, it is understood that, under the condition that the temperature of wash water is maintained in one step within the active temperature range of the first enzyme, cleaning performance if wash water is jetted alternately through the first, second and third nozzles is more excellent than cleaning performance if wash water is jetted through one nozzle (the first nozzle or the third nozzle).

[0170] Further, it is understood that, in case that wash water is jetted alternately through the first, second and third nozzles, cleaning performance if wash water is intensively jetted to the first basket through the first nozzle is more excellent than cleaning performance if wash water is intensively jetted to the second basket and the cutlery through the third nozzle.

[0171] However, if the final temperature of wash water is set to 47°C, it is understood that cleaning performances are almost similar.

[0172] As described above, when tableware is washed under the condition that an enzyme contained in a detergent is activated, if the final temperature of wash water becomes lower than the conventional final temperature, more effective cleaning performance may be exhibited.

[0173] That is, by washing the tableware under the condition that the enzyme contained in the detergent is activated, cleaning performance may be improved and the final temperature of wash water may be lowered, thereby reducing energy consumption.
As is apparent from the above description, in a dishwasher and a control method thereof in accordance with one embodiment of the present invention, active temperatures to maximize activity of contaminant decomposing components, such as enzymes and a surface active agent contained in a detergent, and the most effective maintenance times set according to active features of the detergent are applied to a tableware washing profile, thereby maximizing contaminant decomposing performance of the enzymes and improving tableware cleaning performance.

[0174] Further, since tableware cleaning efficiency is improved as activity of the enzyme is maximized, the maximum temperature of wash water during washing of tableware may be lowered, and thus energy consumed during washing of tableware may be reduced. Further, since a position from wash water is jetted and the amount of wash water are adjusted according to the kind of enzyme, the contact amount of the enzyme decomposing a target contaminating component may be maximized based on the target contaminating component according to the kind of tableware, and thus tableware cleaning efficiency may be improved.

[0175] Although a few embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles of the invention, the scope of which is defined in the claims.

Claims

1. A dishwasher comprising:

a washing tub accommodating a detergent containing a first enzyme activated at an active temperature range and a second enzyme activated at another active temperature range differing from the active temperature range of the first enzyme, and wash water in which the detergent is dissolved;

a heating unit heating wash water; and

a controller controls driving of the heating unit such that the temperature of wash water is maintained within the active temperature range of the first enzyme for a first designated time, and controls driving of the heating unit such that the temperature of wash water is maintained within the active temperature range of the second enzyme for a second designated time, when the first designated time has elapsed.

2. The dishwasher according to claim 1, wherein the first enzyme is α-amylase, and the second enzyme is protease.

3. The dishwasher according to claim 1, further comprising a temperature detection unit detecting the temperature of wash water,
wherein the controller controls driving of the heating unit based on the detected temperature of wash water.

4. The dishwasher according to claim 1, wherein:

the active temperature range of the first enzyme is 32°C to 38°C; and

the active temperature range of the second enzyme is 45°C to 55°C.

5. The dishwasher according to claim 4, wherein the controller controls driving of the heating unit such that the temperature of wash water is raised step by step within the active temperature range of the first enzyme.

6. The dishwasher according to claim 5, wherein:

the active temperature range of the first enzyme includes a first maintenance temperature range and a second maintenance temperature range higher than the first maintenance temperature range; and

the controller controls driving of the heating unit such that the temperature of wash water is maintained within the first maintenance temperature range for a first maintenance time, and controls driving of the heating unit such that the temperature of wash water is maintained within the second maintenance temperature range for a second maintenance time.

7. The dishwasher according to claim 1, further comprising:

a sump provided within the washing tub;

a circulation unit circulating wash water in the sump; and

a nozzle unit jetting wash water supplied from the circulation unit,

wherein the controller controls driving of the circulation unit for the first designated time such that wash water maintained within the active temperature range of the first enzyme is circulated and jetted, and controls driving of the circulation unit for the second designated time such that wash water maintained within the active temperature range of the second enzyme is circulated and jetted.

8. The dishwasher according to claim 1, further comprising:

a first basket, a second basket provided above the first basket, and a cutlery basket provided above the second basket,

wherein the nozzle unit includes a first nozzle provided below the first basket, a second nozzle provided between the first basket and the second basket, and a third nozzle provided above the cutlery basket; and

further comprising:

a first valve blocking wash water supplied to the first nozzle, a second valve blocking wash water supplied to the second nozzle, and a third valve blocking wash water supplied to the third nozzle,

wherein the controller controls opening and closing of the first, second and third valves such that the amount of wash water jetted through the first nozzle is greater than the amount of wash water jetted through the second and third nozzles during control for the first designated time.

9. The dishwasher according to claim 8, wherein the controller controls at least one of opening degrees, opening times and the numbers of opening frequencies of the first, second and third valves such that that the amount of wash water jetted through the second nozzle is greater than the amount of wash water jetted through the third nozzle.

10. The dishwasher according to claim 8, wherein the controller controls opening and closing of the first, second and third valves such that the amount of wash water jetted through the second nozzle is greater than the amount of wash water jetted through the first and third nozzles during control for the second designated time, and controls opening and closing of the first and third valves such that the amount of wash water jetted through the third nozzle is greater than the amount of wash water jetted through the first nozzle.

11. A control method of a dishwasher which has a washing tub and a heating unit heating wash water in the washing tub, comprising:

heating, circulating and jetting wash water in which a detergent is dissolved, when water is supplied to the washing tub;

detecting the temperature of wash water in the washing tub;

judging whether or not the detected temperature of wash water is within an active temperature range of a first enzyme contained in the detergent;

circulating and jetting wash water within the active temperature range of the first enzyme for a first designated time while maintaining the temperature of wash water within the active temperature range of the first enzyme, upon judging that the detected temperature of wash water is within the active temperature range of the first enzyme;

reheating wash water when the first designated time has elapsed;

detecting the temperature of reheated wash water in the washing tub;

judging whether or not the detected temperature of reheated wash water is within an active temperature range of a second enzyme contained in the detergent;

circulating and jetting wash water within the active temperature range of the second enzyme for a second designated time while maintaining the temperature of wash water within the active temperature range of the second enzyme, upon judging that the detected temperature of wash water is within the active temperature range of the second enzyme; and

turning the heating unit off when the second designated time has elapsed.

12. The control method according to claim 11, wherein:

the circulating and jetting of wash water within the active temperature range of the first enzyme for the first designated time while maintaining the temperature of wash water within the active temperature range of the first enzyme includes raising the temperature of wash water step by step within the active temperature range of the first enzyme; and

the raising of the temperature of wash water step by step within the active temperature range of the first enzyme includes maintaining the temperature of wash water within a first maintenance temperature range for a first maintenance time, and maintaining the temperature of wash water within a second maintenance temperature range for a second maintenance time by reheating wash water, when the first maintenance time has elapsed.

13. The control method according to claim 11, wherein the circulating and jetting of wash water includes:

pumping wash water in the washing tub; and

respectively controlling opening and closing of a first valve blocking wash water supplied to a first nozzle provided below a first basket, a second valve blocking wash water supplied to a second nozzle provided between the first basket and a second basket, and a third valve blocking wash water supplied to a third nozzle provided above a cutlery basket.

14. The control method according to claim 13, further comprising:

(a) controlling opening of the first, second and third valves such that wash water is simultaneously jetted through the first, second and third nozzles, upon judging that the detected temperature of wash water is not within the active temperature range of the first enzyme;

(b) controlling opening of the first, second and third valves such that wash water is alternately jetted through the first, second and third nozzles, upon judging that the detected temperature of wash water is not within the active temperature range of the first enzyme; and

(c) controlling opening of the second valve such that wash water is jetted through the second nozzle, upon judging that the detected temperature of wash water is not within the active temperature range of the first enzyme,

wherein at least one of (a), (b) and (c) is performed.

15. The control method according to claim 13, wherein the circulating and jetting of wash water within the active temperature range of the first enzyme includes controlling opening and closing of the first, second and third valves such that a first jet pattern of jetting wash water through the first, second and third nozzles and a second jet pattern of jetting wash water through the first nozzle are alternately executed.

Drawing