JP3899642B2 - Dishwasher - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a dishwasher equipped with a washing pump for pressurizing washing water.
[0002]
[Prior art]
A conventional dishwasher will be described with reference to FIGS. 10 and 11. When washing dishes, the dishes that are the objects to be washed are stored in the dish basket 32 of the washing tub 31, and the detergent is introduced to start the operation. When the operation is started, first, a water supply process of supplying a predetermined amount of cleaning water to the cleaning tank 31 is executed so that the operation of pressurizing the cleaning water by the cleaning pump 33 is stabilized. The cleaning pump 33 has an impeller 34 and an electric motor 35 that drives the impeller 34.
[0003]
Subsequent to the water supply process, a main cleaning process is performed in which the cleaning water pressurized by the cleaning pump 33 and heated by the heater 36 is sprayed from the spray nozzle of the cleaning nozzle 37 together with the detergent. The cleaning water is sprayed vertically or obliquely upward from the spray nozzle 37. Further, the cleaning nozzle 37 is rotated substantially horizontally by the jet reaction force. The tableware is washed by the action of the collision force, detergent, heat, etc. of the washing water sprayed from the washing nozzle 37 rotating in this way.
[0004]
When the cleaning water rises to a predetermined temperature and the main cleaning process for a predetermined time has passed, the process enters a draining process in which the cleaning water containing dirt washed off from tableware and the like is discharged to the outside by the drain pump 38. Subsequently, a water supply process for newly supplying cleaning water, a rinsing process for spraying cleaning water from the cleaning nozzle 37 in order to rinse the dishes contaminated with detergents and leftovers (dirt adhering to the dishes is also called leftovers), The draining process is continuously repeated four times to complete the cleaning process.
[0005]
Moreover, in order to perform the drying process of the next process in a short time, the final rinsing process is a heating rinsing process performed while heating the cleaning water by the heater 36. Reference numeral 39 denotes a control device that controls the cleaning pump 33, the heater 36, the drainage pump 38, and the like.
[0006]
[Problems to be solved by the invention]
The above-described conventional dishwasher has the following problems with respect to the operation of the washing pump in the washing process.
[0007]
In the cleaning process, when air is sucked into the cleaning pump 33, the cleaning water cannot be pressurized. In a conventional general centrifugal pump, when the amount of air increases, pumping becomes impossible. The amount of air that can be pumped is 10 to 15% or less. Further, in such a state containing air, the operation state of the cleaning pump 33 is unstable, and a large operation noise is generated.
[0008]
In the dishwasher, when the cleaning pump 33 is in a state of sucking air, it means that the injection force from the cleaning nozzle 37 and its rotation cannot be normally performed. That is, there is a possibility that a predetermined cleaning power as a dishwasher cannot be obtained.
[0009]
In order to prevent the predetermined detergency from being obtained, the amount of water supplied for the cleaning water is a large amount of water supply in order to obtain the amount of water and the water depth that does not allow air to enter the cleaning pump 33 in the cleaning process. The amount is set as a predetermined amount. On the other hand, the heating capacity of the heater 36 is limited by the power supply capacity of the device. Therefore, in order to heat the large amount of washing water and tableware to a predetermined temperature at which the washing power can be sufficiently exerted in the washing process, a long operation and power consumption are required.
[0010]
In addition, since the cleaning water is circulated to the cleaning pump 33 while the leftovers are separated by the filter 40 during cleaning, the clogging of the filter 40 is caused by the cleaning pump 33 as the filtering of the filter 40 progresses. It becomes a resistance when sucking in the washing water, and the washing pump 33 becomes easy to suck in air.
[0011]
Therefore, the present invention solves the problems of the conventional dishwasher as described above. In particular, the specific impeller configuration of the washing pump can save water and obtain a predetermined washing performance in a short time. The object is to provide a dishwasher that can be used.
[0012]
[Means for Solving the Problems]
In order to solve the above problems, a dishwasher according to the present invention includes a tableware for storing an object to be cleaned, a cleaning tank that houses the tableware basket, a cleaning nozzle having an injection port for injecting cleaning water, and an electric motor. a washing pump for pressurizing flush water at an impeller to be driven, a control device for controlling the driving of said electric motor, said impeller outlet angle with respect to a predetermined rotation direction to the inner portion with respect to the rotating center A rearward-facing inner blade set to approximately 90 degrees or less, and a large outer blade and a small outer blade having different blade heights whose outlet angles are set to approximately 90 degrees or more on the outer side with respect to the center of rotation. The outer blade is connected to the inner blade, the small outer blade is lower than the height of the large outer blade, and the small outer blade is provided between the large outer blades. Not to be next to each other Than is.
[0013]
According to this invention, the absolute velocity of the fluid flowing out from the outer blade is higher than the absolute velocity of the fluid flowing out from the inner blade when the washing water is mixed with air in the washing step and sent to the washing pump. Because of its large size, air is sent to the outer periphery of the impeller. For this reason, an inner blade | wing can be filled with washing water with a small mixing ratio of air, and can pressurize washing water. Then, air and washing water can be sent to the washing nozzle, and the washing water can be ejected by the washing nozzle and rotated normally.
[0014]
In particular, by forming the inner blades in the rearward shape and forming the forward-shaped portions in the outer blades, it is possible to feed the cleaning water and the cleaning nozzle in a comparative manner.
[0015]
Further, the number of impeller blades is larger than that of the inner blades, so that the air discharge flow rate is large, and the air can be discharged from the cleaning pump in a shorter time.
[0016]
Further, since wash water containing air can be pressurized and circulated with an impeller, the amount of wash water to be supplied can be reduced as compared with a general centrifugal pump. Therefore, the heat capacity when heating washing water and tableware becomes small, and it can be heated to a predetermined temperature in a short time with the same heating capacity as before. Therefore, it is possible to provide a dishwasher capable of obtaining predetermined cleaning performance and drying performance in a short time.
[0017]
Further, the outer blade is composed of a large outer blade and a small outer blade, and the small outer blade is larger than the large outer blade and the inner blade in the distance to the inner surface of the casing of the washing pump having the impeller built therein, and the small outer blade. By arranging the blades in the gap between the large outer blades on the extension of the gap between the inner blades, there is a certain size between the small outer blade and the casing inner surface of the washing pump from the inlet to the outlet of the impeller. Have been able to get. In other words, even if solids of a size that can pass through the filter or foreign matter prevention means enter the cleaning pump, the impeller blades are not clogged and easily discharged outside the cleaning pump. The pressurizing ability is stable over a long period of time.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the configuration described in each example can be an embodiment. That is, as in the first aspect of the invention, it is driven by an electric motor as well as a tableware for storing an object to be cleaned, a cleaning tank in which the tableware basket is installed, a cleaning nozzle having an injection port for spraying cleaning water. includes a washing pump for pressurizing flush water in the impeller, a control device for controlling the driving of the motor, the impeller is approximately 90 degrees exit angle with respect to a predetermined rotation direction to the inner portion with respect to the rotating center A rearwardly-facing inner blade set below, and a large-side blade and a small-side blade having different blade heights, each having an outlet angle set to approximately 90 degrees or more on the outer side with respect to the rotation center, The small outer blade is connected to the inner blade, and the small outer blade is lower than the large outer blade , and the small outer blade is provided between the large outer blades , and the large outer blades are not adjacent to each other. Because Because the absolute velocity of the fluid flowing out from the outer blade is large when air is mixed into the cleaning water in the cleaning process and sent to the cleaning pump, the air quickly moves to the outer periphery of the impeller. It is sent. For this reason, an inner blade | wing can be filled with washing water with a small mixing ratio of air, and can pressurize washing water. Then, air and washing water can be sent to the washing nozzle, and the washing water can be ejected by the washing nozzle and rotated normally.
[0019]
The inner blade has a shape inclined backward with respect to the predetermined rotation direction of the impeller, and the outer blade has a shape facing forward with respect to the predetermined rotation direction of the impeller so that fluid can easily flow out to the outer periphery at the outermost peripheral portion of the impeller. By forming it so as to have a portion, the cleaning water can send air to the outer periphery of the impeller, and the cleaning water can be efficiently sent to the cleaning nozzle. Therefore, it is effective for normal rotation of the impeller.
[0020]
Further, the number of impeller blades is larger than the number of inner blades, so that the air discharge flow rate is large and air can be discharged in a shorter time. For this reason, when the amount of cleaning water to be supplied is set to be smaller than that of a general centrifugal pump, or when leftovers are collected in the filter as the cleaning process proceeds, and there are few openings through which the cleaning water passes. Even in a state where air easily enters, the washing water can be pressurized and circulated with the impeller. That is, the washing operation can be performed with less washing water and a smaller heat capacity of the tableware and the washing water. Therefore, even with the same heating capacity, the cleaning water can be heated to a predetermined temperature in a short time, and predetermined cleaning performance and drying performance can be obtained.
[0021]
In the invention according to claim 2, the control device can reverse the direction of rotation of the motor between each step of the cleaning process or within each step of the cleaning step so that the rotation direction of the impeller can be switched. Yes, the electric motor is reversed and operated in the cleaning process, and the shape of the outer blades of the impeller is switched between forward and backward depending on the rotation direction. In the forward direction, the absolute velocity of the fluid is large and the pressurization capacity of the cleaning pump is high. On the contrary, in the backward direction, the absolute velocity of the fluid is small, and the pressurizing capacity of the cleaning pump is low. Thus, the pressurization capacity of the washing pump is switched between large and small. That is, the jetting pressure of the cleaning nozzle can be adjusted to be strong or weak. By providing a control device that can select this between each process, it has both a powerful cleaning power that can clean sticky dirt and a standard cleaning power that can clean normal dirt.
[0022]
In addition, by providing a control device that alternately switches the electric motor between a predetermined rotation direction and reverse rotation in each process, the pressurization capacity of the cleaning pump can be increased without increasing the amount of cleaning water, and the cleaning nozzle Since the injection pressure can be temporarily increased, water-saving high-pressure cleaning can be performed.
[0023]
The invention according to claim 3 is provided with a drainage pump for discharging the wash water to the outside of the machine, and the control device rotates the impeller of the wash pump at the time of washing in parallel with the operation of the drainage pump in the drainage process. It is made to rotate in the opposite direction, and is drained out of the machine while spraying cleaning water from the cleaning nozzle onto the object to be cleaned.
[0024]
Therefore, while rinsing dirt adhering to the tableware and stirring light dirt with a specific gravity contained in the washing water, it can be discharged out of the machine together with the washing water from the bottom of the washing tank by the drain pump. In addition, since the impeller rotates in the reverse direction in the drainage process, the inner blade acts as a forward blade, so that the washing water can be pressurized with a small load.
[0025]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
[0026]
Example 1
1 and 2, 1 is a washing tank, 2 is a dish basket for storing objects to be cleaned such as dishes and cooking tools, 3 is a washing pump for pressurizing washing water, 4 is an impeller of the washing pump 3, and 5 is this An electric motor that drives the impeller 4. 6 is a heater for heating the cleaning water, 7 is a cleaning nozzle having an injection port for injecting the cleaning water, and 8 is a drainage pump for discharging the cleaning water out of the apparatus. Reference numeral 9 denotes a control device that controls the operation of the cleaning pump 3, the heater 6, and the like.
[0027]
In particular, the impeller 4 has a rearward inner blade 4a whose outlet angle is set to 90 degrees or less with respect to a predetermined rotation direction on the inner side with respect to the rotation center as shown in FIG. It has a forward outer blade 4b whose angle is set to 90 degrees or more, and the number of blades of the impeller 4 is formed so that the number of outer blades 4b is larger than the number of inner blades 4a. That is, the outer blade 4b has 1 of the large outer blade 4b and 2 of the small outer blade 4b, and has 2 of the small outer blade 4b in the middle of 1 of the large outer blade 4b.
[0028]
As shown in FIG. 4, the outer blade 4b is formed at least at a level of 2 or higher and is composed of one large outer blade 4b having a height H1 and two small outer blades 4b having a height H2. . And it arrange | positions as shown in FIG. 3 so that 1 of the large outer side blade | wings 4b may not adjoin each other.
[0029]
Next, the operation of the dishwasher of this embodiment will be described. Since the operation in the cleaning process is basically the same as the conventional one, the description thereof is omitted. The characteristic operation in the present embodiment is the operation of the cleaning pump 3 in the cleaning process.
[0030]
In the cleaning process, as the process proceeds, leftovers are collected in the filter, and the cleaning water is hardly supplied to the cleaning pump 3. Accordingly, the suction force of the cleaning pump 3 causes the cleaning water to be sent to the cleaning pump 3 in a state where air is mixed. At this time, since the absolute velocity of the fluid flowing out from the outer blade 4 b is large, air is sent to the outer peripheral portion of the impeller 4.
[0031]
Therefore, the inner blade 4a of the impeller 4 can be filled with cleaning water having a small air mixing ratio and pressurize the cleaning water. Then, air and washing water can be sent to the washing nozzle 7 and sprayed from the washing nozzle 7 and rotated normally. Further, the number of impeller 4 blades is arranged so that the total number of large outer blades 4b and outer small blades 4b, which are outer blades, is larger than the number of inner blades 4a. Increases and air can be discharged in a shorter time.
[0032]
Since the wash water containing air can be pressurized and circulated with the impeller 4 as described above, the amount of wash water supplied in the washing process is smaller than that of a general centrifugal pump. In this embodiment, it can be reduced. Therefore, even if the heat capacities of the washing water and the tableware are reduced and the heating capacity of the heater 6 is the same, it can be heated to a predetermined temperature in a short time.
[0033]
In addition, when the filter is not correctly mounted in the cleaning process, foreign matter having a size smaller than a certain amount that passes through a second filter (not shown) that prevents foreign matter from entering the cleaning pump 3. Will occur. However, in the present embodiment, the outer blade 4b having a large number of blades and a small gap has two large blades 4b and two small blades 4b, the blade heights of which are different between H1 and H2. Since the blades 4b are arranged so that the blades 4b are not adjacent to each other, the gap between the outer blades 4b can always have a certain size or more from the entrance to the exit.
[0034]
For this reason, even if the foreign matter 4c enters the cleaning pump 3, it is discharged to the outside of the cleaning pump 3 by the gap between the casing of the cleaning pump 3 and the outer blade 4b of the impeller 4 as shown in FIG. There is no clogging. For example, the foreign matter 4c that has passed between the blades of the inner blade 4a at the entrance of the cleaning pump 3 passes through the gap formed by the small outer blade 4b 2 and the inner surface 3a of the cleaning pump 3 at the outer portion of the impeller 4, It is discharged out of the cleaning pump 3. Therefore, the pressurization capacity of the cleaning pump 3 is stabilized under various operating conditions.
[0035]
Thus, the pressurization capability of the cleaning pump 3 can be maintained as it is, and the amount of cleaning water supplied can be reduced. This makes it possible to shorten the heating time for raising the washing water to a predetermined temperature in the washing step and the heating rinse step with the same heating ability. That is, of course, predetermined cleaning performance and drying performance can be obtained, but water saving and operation time of the cleaning process can be shortened and power can be saved.
[0036]
Depending on the type and amount of dirt, in each of the rinsing steps performed by replacing the washing water, the pressurization capacity of the washing pump 3 is stable even if the washing water is further reduced. 7, the injection can be performed normally, and the necessary rinsing effect can be obtained. Of course, this also shortens the heat rinsing time and saves power.
[0037]
In the drying process, air is sent into the washing tank 1 from outside the machine by a blower (not shown), the heater 6 is intermittently operated to generate warm air, and water droplets adhering to the tableware are evaporated by this warm air. The humid air in the cleaning tank 1 is discharged out of the machine through an exhaust port (not shown). Therefore, in this embodiment, if the control device 9 performs the heating and rinsing process for the same operating time as the conventional one, the temperature of the dishes and the attached water droplets can be made higher than that of the conventional dishwasher. Therefore, the drying speed of the object to be cleaned is improved, so that the drying performance can be improved and the drying time can be shortened. In this way, the entire operation time can be shortened including the drying.
[0038]
(Example 2)
In this embodiment, the basic configuration is similar to that in Embodiment 1, and includes a washing tub 1, a dish basket 2, a washing pump 10, an impeller 4, an electric motor 5, a heater 6, a washing nozzle 7, and a drainage pump 8. A description of the basic configuration is omitted. As shown in FIG. 6, the rotation direction of the cleaning pump 10 is also controlled by the controller 12 that controls the operation of the cleaning pump 10, the heater 6, and the like by the forward / reverse reversing means 11 of the electric motor 5. The impeller 4 has blades similar to those in the first embodiment.
[0039]
And the driving | operation in a washing | cleaning process is demonstrated. In this embodiment, in particular, by selecting and operating the rotation direction of the electric motor 5 in the cleaning process, the outer blades of the impeller 4 can be switched forward and backward, and the pressurization capacity of the cleaning pump 10 is switched between large and small. be able to. That is, as shown in FIG. 7, although the load of the cleaning pump 10 increases from W1 to W2, the pressurization capability increases, and the injection pressure of the cleaning nozzle 7 increases from P1 to P2. This makes it possible to select an appropriate detergency according to the amount and quality of dirt.
[0040]
In this way, by providing the control device 12 that can select the spraying force of the cleaning nozzle 7 between the respective processes, it has a strong cleaning power that can clean sticky dirt and a standard cleaning power that can clean normal dirt. Washing can be obtained with a single dishwasher.
[0041]
In addition, the control device 12 alternately switches the electric motor 5 between a predetermined rotation direction and a reverse rotation within each cleaning process, thereby increasing the pressurization capacity of the cleaning pump 10 without increasing the amount of cleaning water. Thus, the spray pressure of the cleaning nozzle 7 can be temporarily increased.
[0042]
That is, since the cleaning pump 10 recovers the pressurization capacity in a short time against the mixing of air in the same manner as the cleaning pump 3 of the first embodiment due to the effect of the impeller 4 blades, the amount of circulating water increases. However, the operation can be performed without adding the amount of cleaning water to be supplied, and the injection pressure of the cleaning nozzle 7 can be increased as shown in FIG.
[0043]
In this regard, the means of adjusting the rotation speed with a conventional centrifugal impeller to increase the pressurizing capacity requires that the amount of cleaning water supplied be increased in conjunction with the amount of circulating water, and is difficult to obtain. It is. Therefore, it is possible to perform high-pressure cleaning with a water-saving type as compared with the conventional method, and it is possible to simultaneously improve the cleaning power and reduce the amount of water used.
[0044]
Furthermore, when the cleaning water is at a predetermined temperature or lower in the cleaning process, the controller 12 can drive the impeller 4 of the cleaning pump 10 mainly in the reverse rotation direction to reduce the pressurization capacity of the cleaning pump 10. As a result, the spraying force of the cleaning nozzle 7 is weakened, and the cleaning noise due to the collision or dripping of the cleaning water into the cleaning tank 1 can be reduced. And a dirt is swollen, heating a to-be-washed object and washing water.
[0045]
Thereafter, when the cleaning water reaches a predetermined temperature or higher, the control device 12 drives the impeller 4 of the cleaning pump 10 mainly in a predetermined rotation direction to return the pressurization capacity of the cleaning pump 10 to the standard state, thereby cleaning. The spraying force of the nozzle 7 can be increased to clean the dirt. That is, the predetermined cleaning performance can be obtained and the operation noise in the cleaning process can be reduced in most of the time.
[0046]
(Example 3)
The basic configuration of this embodiment is the same as that of the second embodiment, and a description of the basic configuration is omitted. As shown in FIG. 6, the cleaning pump 10 is controlled by a control device 12 with forward / reverse inversion means 11. And the operation | movement in a drainage process is demonstrated.
[0047]
At the same time as the drainage pump 8 is operated in the drainage process, the cleaning pump 10 is operated as shown in FIG. Here, the forward / reverse reversing means 11 rotates the electric motor in the direction opposite to the cleaning step. That is, a control device 12 that drives the impeller 4 in a direction opposite to the predetermined rotation direction is provided.
[0048]
In this way, by operating the cleaning pump 10 in the drainage process, the drainage pump 8 drains water while spraying the cleaning water from the cleaning nozzle 7 onto the object to be cleaned. Then, while rinsing dirt adhering to the tableware and stirring light dirt with a specific gravity contained in the washing water, it can be discharged out of the machine by the drainage pump 8 from the bottom of the washing tank 1.
[0049]
The dirt having a low specific gravity is a dirt that floats on the upper surface of the cleaning water in the conventional drainage process and tends to remain on the bottom surface even if drained from the bottom of the cleaning tank 1.
[0050]
In addition, since the impeller 4 rotates in the reverse direction in the drainage process, the inner blade acts as a forward blade, so the washing water is pressurized with a small load. Therefore, as the energization amount of the device, an excellent rinsing effect can be obtained only by adding the cleaning pump 10 slightly. The impeller 4 has a large load in a predetermined rotation direction, but since the washing water is also strongly injected, the control device 12 can control the rotation direction to enhance the rinsing effect.
[0051]
With such a high rinsing effect, depending on the amount and quality of dirt, the number of rinsing steps is reduced, and the amount of water used per washing operation and the power consumption throughout the operation are reduced. can do.
[0052]
Note that phase control and inverter control are often performed as rotation control means of the electric motor 5. Of course, if the electric motor 5 is a DC brushless motor, the rotational speed can be controlled in a wider range.
[0053]
【The invention's effect】
Since this invention is comprised as mentioned above, it has the effect described below.
[0054]
According to the invention of claim 1, the tableware basket for storing the object to be cleaned, the cleaning tank in which the tableware basket is housed, the cleaning nozzle having the injection port for spraying the cleaning water, and the impeller driven by the electric motor a washing pump for pressurizing flush water Te, a control device for controlling the driving of the motor, the impeller is below approximately 90 degrees exit angle with respect to a predetermined rotation direction to the inner portion with respect to the rotating center A rearward-facing inner blade set, and a large outer blade and a small outer blade with different blade heights whose outlet angle is set to approximately 90 degrees or more on the outer side with respect to the rotation center, and the large outer blade is the inner blade The small outer blades are connected to the blades, the height of the small outer blades is lower than that of the large outer blades , and the small outer blades are provided between the large outer blades so that the large outer blades are not adjacent to each other. So it contained air Since the cleaning water in a state can be pressurized and circulated with an impeller, the cleaning water supplied in the cleaning process can be reduced, heated to a predetermined temperature in a short time, and clogged with foreign matter. In addition, the pressurization capacity of the washing pump can be obtained stably.
[0055]
According to the invention described in claim 2, the control device can reverse the direction of rotation of the electric motor between each step of the cleaning step or within each step of the cleaning step so that the rotation direction of the impeller can be switched. Therefore, the spraying pressure of the cleaning water sprayed from the cleaning nozzle can be adjusted.
[0056]
According to a third aspect of the present invention, the drainage pump for discharging the washing water to the outside of the machine is provided, and the control device is configured to wash the impeller of the washing pump in parallel with the operation of the drainage pump in the drainage process. Since it is made to rotate in the direction opposite to the rotation direction, the washing water can be discharged outside the apparatus while rinsing dirt adhering to the tableware, and the rinsing performance can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an essential part of a dishwasher according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view of an essential part of a pump according to the same embodiment. Cross-sectional view of the impeller in the pump of the same embodiment FIG. 5 Cross-sectional view of the other parts of the pump of the same embodiment FIG. 6 Cross-sectional view of the main parts of the dishwasher in the second embodiment of the present invention FIG. 8 is a second time chart showing the injection pressure in the same embodiment. FIG. 9 is a time chart showing the operation of the cleaning pump in the third embodiment of the invention. FIG. 10 is a cross-sectional view of a main part of a conventional dishwasher. FIG. 11 is a cross-sectional view of a main part of a cleaning pump in the conventional example.
DESCRIPTION OF SYMBOLS 1 Washing tank 2 Tableware basket 3,10 Washing pump 3a Casing inner surface 4 Impeller 4a Inner blade 4b Outer blade 4b 1 Large outer blade 4b 2 Small outer blade 4c Foreign matter 5 Electric motor 6 Heater 7 Washing nozzle 8 Drain pump 9, 12 Control device 11 Forward / reverse inversion means W1 Input of cleaning pump P1 Injection pressure of cleaning nozzle

Claims (3)

A tableware basket for storing objects to be cleaned, a cleaning tank in which the tableware basket is installed, a cleaning nozzle having an injection port for injecting cleaning water, a cleaning pump for pressurizing the cleaning water with an impeller driven by an electric motor, a control device for controlling the driving of the motor, the impeller includes a rearwardly facing inner vane set an exit angle below approximately 90 degrees with respect to a predetermined rotation direction to the inner portion relative to the rotational center, the center of rotation The outer side has a large outer blade and a small outer blade with different blade heights , the outlet angle being set to approximately 90 degrees or more, and the large outer blade is connected to the inner blade and the small blade The outer blade is lower than the height of the large outer blade, and the small outer blade is provided between the large outer blades so that the large outer blades are not adjacent to each other. 2. The dishwasher according to claim 1, wherein the controller reverses the direction of rotation of the electric motor between each step of the cleaning step or within each step of the cleaning step so that the rotation direction of the impeller can be switched. A drainage pump for discharging washing water to the outside of the machine is provided, and the control device rotates the impeller of the washing pump in a direction opposite to the rotation direction during washing in parallel with the operation of the drainage pump in the drainage process. Item 3. A dishwasher according to item 1 or 2.

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