Tableware washing machine using induction heating

Abstract

A dishwashing machine includes: a housing having an internal washing space; a liquid inlet for adding clean water therein; a liquid outlet for removing dirty liquid; a first water tank for receiving water from the liquid inlet, the first water tank comprising a first heating system for heating clean water; a first conduit for delivering the heated clean water to the at least one spray nozzle; a second water tank configured to receive the heated clean water from the internal washing space, the second water tank including a second heating system for heating the heated clean water to form heated wash water; and a second conduit for delivering the heated wash water to the at least one spray nozzle in order to spray the heated wash water into the interior wash space. At least one of the first heating system and the second heating system heats water by induction.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to the field of dishwashers, and in particular to dishwashers that use induction heating. BACKGROUND

[0002] Commercial establishments for cooking and / or preparing food typically have commercial dishwashers for washing soiled dishes. The dishwashers spray cleaning agents and water onto the soiled dishes to clean the dishes. The dishwashers can also spray rinse aids and water onto the dishes after the dishes have been washed to rinse the dishes and prevent stains on the dishes.

[0003] Currently, there are four main types of commercial dishwashers on the market worldwide. The commercial dishwashers include under-the-counter dishwashers, hood or door-type dishwashers, tunnel-type dishwashers, and flight-type dishwashers. The under-the-counter dishwashers have a small size and low profile and are positioned under a separate workbench with a sink basin next to the space occupied by the under-the-counter dishwashers. The hood or door-type dishwashers, tunnel-type dishwashers, and flight-type dishwashers all have a medium to large size and are positioned next to a separate side bench with a sink basin on the bench. The under-the-counter dishwashers, hood or door-type dishwashers, and tunnel-type dishwashers all typically use racks or containers with soiled dishes positioned within the machine. The flight-type dishwashers have dishes placed directly onto an integral conveyor belt and washed as the dishes pass therethrough.

[0004] More efficient and environmentally friendly commercial dishwashers are desirable. SUMMARY

[0005] According to one aspect, the present invention relates to a dishwasher comprising: a housing having an interior wash space for washing dishes; a liquid inlet for adding clean water to the dishwasher; a liquid outlet for removing soiled liquid from the dishwasher; a first water tank for receiving water entering the housing through the liquid inlet, wherein the first water tank comprises a first heating system for heating the clean water to form heated clean water; a first conduit for delivering the heated clean water to at least one spray nozzle for spraying the heated clean water onto dishes positioned within the interior wash space; a second water tank configured to receive the heated clean water from the interior wash space, wherein the second water tank comprises a second heating system for heating the heated clean water to form heated wash water; and a second conduit for delivering the heated wash water to at least one spray nozzle for spraying the heated wash water into the interior wash space. At least one of the first heating system and the second heating system heats the water by induction.

[0006] Another aspect of the present disclosure is to provide a method of washing dishware, comprising: providing a housing having an interior washing space for receiving dishware; adding clean water to the dishwashing machine; delivering the clean water to a first water tank; heating the clean water in the first water tank with a first heating system to form heated clean water; supplying the heated clean water to at least one spray nozzle; spraying the heated clean water onto dishware positioned within the interior washing space; delivering the heated clean water from the interior washing space to a second water tank; heating the heated clean water in the second water tank with a second heating system to form heated wash water; delivering the heated wash water to at least one spray nozzle; and spraying the heated wash water into the interior washing space. At least one of the first heating system and the second heating system heats water by induction. BRIEF DESCRIPTION OF DRAWINGS

[0007] One or more embodiments of the present disclosure are illustrated by way of example, and not limitation, in the figures of the drawing and in which like references indicate similar elements, in which:

[0008] Figure 1 is a front perspective view of a dishwashing machine according to a first embodiment of the present disclosure.

[0009] Figure 2 is a front perspective exploded view of a dishwashing machine according to a first embodiment of the present disclosure.

[0010] Figure 3 is a front view of a dishwashing machine according to a first embodiment of the present disclosure.

[0011] Figure 4 is a left side view of a dishwashing machine according to a first embodiment of the present disclosure.

[0012] Figure 5 is a right side view of a dishwashing machine according to a first embodiment of the present disclosure.

[0013] Figure 6 is a partial side view of a portion of a system for supplying water to an interior washing space.

[0014] Figure 7 is an exploded view of a first embodiment of an induction water heating system.

[0015] Figure 8 is a front perspective view of a dishwashing machine according to a second embodiment of the present disclosure.

[0016] Figure 9 is a front perspective exploded view of a dishwashing machine according to a second embodiment of the present disclosure.

[0017] Figure 10is a front view of a warewash machine according to a second embodiment of the present invention.

[0018] Figure 11 is a left side view of a warewash machine according to a second embodiment of the present invention.

[0019] Figure 12 is a right side view of a warewash machine according to a second embodiment of the present invention.

[0020] Figure 13 is an exploded view of a second embodiment of an induction water heating system.

[0021] Certain terminology will only be used in this description for the convenience of the reader and will not be limiting. Such terminology includes specific examples of words, phrases, and symbols. DETAILED DESCRIPTION

[0022] Reference will now be made in detail to implementations and embodiments of various aspects and variations of the present invention, examples of which are illustrated in the accompanying drawings. While at least two variations of systems, methods, and uses are described, other variations of systems, methods, and uses can include aspects of the systems, methods, and uses described herein combined in any suitable manner with all or some of the aspects described.

[0023] Aspects of the present invention are to employ an induction heating system to heat rinse and wash water in a warewash machine. The warewash machine using the induction heating system can be domestic or industrial and can include any type of warewash machine, including under-the-counter warewashers, door / hood / bracket / vertical warewashers, tunnel / conveyor warewashers, and flight-type warewashers. The warewash machine 10 described herein is a hood-type warewasher, but the systems described herein can be used in any type of warewash machine.

[0024] Figures 1-7 Various partial views of a first embodiment of a warewash machine 10 are shown. The warewash machine 10 includes an upper housing portion 20 and a lower housing portion 24. The upper housing portion 20 defines an interior wash space 12 for receiving wares (e.g., glasses, plates, eating and serving utensils, etc.) to be cleaned. A system 22 for supplying water to the interior wash space 12 of the upper housing portion 20 of the warewash machine 10 is primarily located in the lower housing portion 24 of the warewash machine 10, which is located below the upper housing portion 20 of the warewash machine 10.

[0025] The lower housing portion 24 shown holds most of the system 22 for supplying water to the internal washing space 12. The lower housing portion 24 includes a generally rectangular base plate 11 supported by a plurality of legs 13 adjacent to each of its corners. Support rods 15 extend upward from each corner of the generally rectangular base plate 11, with the upper housing portion 20 supported on the top of the support rods 15. Walls surround the lower housing portion 24 to enclose the system 22 within the walls. Figures 1-5 In the middle, one of the wall and support rod 15 is removed to better show the internal components of the lower housing portion 24 of the dishwashing machine 10.

[0026] In the illustrated example, the upper housing portion 20 includes a washing housing 8 enclosing the internal washing space 12 and a control box 7 located on top of the washing housing 8. The control box 7 includes multiple displays, buttons (real or touchscreen), and switches for controlling the settings of the dishwashing machine 10 during use. Such displays, buttons (real or touchscreen), and switches, along with the control system within the control box 7 for controlling the dishwashing machine 10, are well known to those skilled in the art.

[0027] The washing housing 8 shown encloses the internal washing space 12 during the dishwashing process, as described herein. Figure 1 As shown, the washing housing 8 includes a fixed front wall 9, a pair of sliding side walls 17, a fixed rear wall (not shown), and a top wall 6 supporting the control box 7. The pair of sliding side walls 17 are configured to slide vertically in vertically extending grooves on posts 14 located at all four corners of the dishwashing machine 10. A U-shaped handle 19 is pivotally attached to a pair of brackets 21 extending rearward from the rear post 14, as... Figure 1 As shown, this allows the U-shaped handle 19 to pivot about the bracket 21. The side arm 23 of the U-shaped handle 19 extends adjacent to the sliding sidewall 17. When the U-shaped handle 19 pivots about the bracket 21 to move the side arm 23 upward, the first end of the lifting rod 25, rotatably connected to the side arm 23 of the U-shaped handle 19, also rises. As the lifting rod 25 rises, its second end, rotatably connected to the sliding sidewall 17, lifts the sliding sidewall 17 along a groove in the column 14 to open the inner washing space 12, allowing dishes to be positioned in the inner washing space 12 for washing and removed from the inner washing space 12 once the washing sequence is complete. It is envisioned that other door or wall systems could be used to selectively allow access to the inner washing space 12.

[0028] In such a state Figure 2In the illustrated example shown, the interior wash space 12 can include at least one shelf or ledge 27 as known to those skilled in the art to directly hold dishes or to hold trays or racks that hold dishes. The interior wash space 12 of the dishwashing machine 10 includes a top rotary spray arm 16 located at the top of the interior wash space 12 to be positioned above the dishes (and possibly trays or racks) and a bottom rotary spray arm 18 located at the bottom of the interior wash space 12 and below the dishes (and possibly trays or racks) to spray water, wash fluid, and / or rinse fluid onto the dishes to wash and rinse the dishes. Water (fresh water, with a wash detergent, or with a rinse aid) is supplied to the top rotary spray arm 16 and the bottom rotary spray arm 18 to wash and rinse the dishes. The interior wash space 12, the top rotary spray arm 16, and the bottom rotary spray arm 18 are all located in an upper housing portion 20 of the dishwashing machine 10 that is enclosed by the wash housing 8. Other configurations for spraying water onto the dishes are contemplated. For example, the system can use only one of the top rotary spray arm 16 or the bottom rotary spray arm 18, the arms can be stationary, and / or other nozzles (e.g., stationary nozzles extending from the interior walls) can be employed to spray water onto the dishes to wash the dishes.

[0029] Figures 1-5 A system 22 for supplying water to the interior wash space 12 of the dishwashing machine 10 via the top rotary spray arm 16 and the bottom rotary spray arm 18 is shown. The system 22 for supplying water to the interior wash space 12 is primarily located in a lower housing portion 24 of the dishwashing machine 10 that is below the upper housing portion 20 of the dishwashing machine 10.

[0030] In the illustrated embodiment, the system 22 passes water through the system 22 to wash and rinse dishes in the interior wash space 12 of the dishwashing machine 10. The system includes a fresh water connection pipe 26, a fresh water reservoir 28, a rinse water pump 32, a rinse water induction heated tank system 34, a rinse water plumbing 36, the spray arms 16 and 18, a wash water tank 38, a wash water pump 40, a wash water plumbing 42, a hot waste water discharge conduit 46, and a waste water discharge outlet 48. The elements of the system 22 are discussed in more detail below along with the flow path of water through the system 22.

[0031] Water enters the illustrated dishwashing machine 10 through the fresh water connection pipe 26, which in the illustrated example extends through the floor 11 (see Figure 4 and 5). The fresh water connection 26 is connected to an external source of fresh water as is known to those skilled in the art, and the fresh water connection 26 can be connected to the external source of fresh water through the bottom or any side wall of the lower housing portion 24. It is contemplated that the fresh water connection 26 can include a pressure regulator 29 (see Figure 4 ) for regulating the pressure of the input to the warewashing machine 10. The fresh water connection 26 supplies fresh water to the fresh water reservoir 28.

[0032] The illustrated fresh water reservoir 28 holds fresh water before the fresh water is used in the warewashing machine 10, and includes a first stage for heating the water for use in the system 22. The fresh water reservoir 28 includes a fresh water housing 56 having an interior fresh water holding space 58, as shown in Figure 6 . Fresh water from the fresh water connection 26 is supplied to the interior fresh water holding space 58 through a fitting 60 connected to the fresh water housing 56, as shown in Figure 6 . It is contemplated that the fitting 60 can include a filter for preventing contaminants from entering the fresh water reservoir 28. As discussed in more detail below, the fresh water reservoir 28 has the hot waste water exhaust conduit 46 passing therethrough so as to exchange heat from the hot waste water exhaust conduit 46 to the fresh water in the interior fresh water holding space 58. It is noted that if the warewashing machine 10 has not recently been used to wash and rinse wares, the fresh water in the interior fresh water holding space 58 of the fresh water reservoir 28 can not be heated with the hot waste water exhaust conduit 46 because the interior of the hot waste water exhaust conduit 46 will not be hot due to non-activation. As shown in Figure 4 , an overflow pipe 62 can be connected to the top of the fresh water housing 56. The overflow pipe 62 has an upside down U-shaped open end located above the top of the wash water tank 38 so as to allow excess water pressure in the fresh water housing 56 to be released if needed.

[0033] In the illustrated example, the heated fresh water in the interior fresh water holding space 58 of the fresh water reservoir 28 is pumped by the rinse water pump 32 from the interior fresh water holding space 58 to the rinse water induction heated tank system 34. The rinse water pump 32 pulls the heated fresh water in the interior fresh water holding space 58 of the fresh water reservoir 28 through the short conduit 35 and pushes the heated fresh water through the pump conduit 66 to the rinse water induction heated tank system 34.

[0034] The illustrated rinse water induction heated tank system 34 heats the rinse water therein by induction heating. As Figure 7As shown in the middle, the rinse water induction heated tank system 34 includes a rinse water holding tank 100, a heat insulating cylinder 102 surrounding the rinse water holding tank 100, an induction coil 104 coiled around the heat insulating cylinder 102, and a plurality of magnetic shielding bars 106 connected to the induction coil 104 and supporting the induction coil 104. The rinse water holding tank 100 can have any cross-sectional shape (e.g., circular and square), and receives heated fresh water through a filter inlet pipe 108 extending through a top surface 110 of the rinse water holding tank 100. The heat insulating cylinder 102 tightly surrounds an outer surface 112 of the rinse water holding tank 100 to minimize heat escaping from the heated rinse water in the rinse water holding tank 100. The coil 104 is coiled around the heat insulating cylinder 102. A pulsed direct current or a high frequency alternating current passes through the coil 104, thereby generating a magnetic flux and generating an electric current in the conductive material of the rinse water holding tank 100. In induction heating, the magnetic flux from the coil 104 heats the conductive material of the rinse water holding tank 100, where the metal conductive material has better magnetic properties than metals having low magnetic properties or no magnetic properties. In the preferred embodiment, the rinse water holding tank 100 is formed of stainless steel 430 or stainless steel SUS201. Also, in the preferred embodiment, a rinse aid is added to the water after the rinse water exits the rinse water induction heated tank system 34 to avoid corrosion in the rinse water holding tank due to the rinse aid chemicals. A bracket 114 connected to the bottom of the rinse water holding tank 100 is used to support the rinse water induction heated tank system 34 on the floor 11.

[0035] After the heated fresh water is further heated in the rinse water induction heated tank system 34, the rinse water pump 32 is further activated to push the further heated fresh water through the rinse water conduit 36. The rinse water conduit 36 includes a first rinse water conduit path 70 leading to the top rotary spray arm 16 and a second rinse water conduit path 72 leading to the bottom rotary spray arm 18. If other devices are used to spray water onto the dishes as discussed above, the further heated fresh water in the rinse water conduit 36 will be delivered to those other devices with conduits.

[0036] After the further heated fresh water is sprayed by the top rotary spray arm 16 and the bottom rotary spray arm 18 onto the dishes in the interior washing space 12, the further heated fresh water will fall to the wash water tank 38 located at the bottom of the interior washing space 12, which has a drain 74 connected to the sump 40. The further heated fresh water will be pumped by the wash water pump 30 through the wash water conduit 26 to the top rotary spray arm 16 and the bottom rotary spray arm 18 for further spraying onto the dishes in the interior washing space 12. Figure 2The further heated clean water will collect within the wash water tank 38 and will be further heated by a positive temperature coefficient (PTC) heating element 74 in order to further heat the heated water within the wash water tank 38. The PTC heating element 74 is fully disclosed in U.S. Patent Application Serial No. 18 / 457,569 entitled Safe and Efficient Dishwasher, the entire contents of which are hereby incorporated by reference herein. A wash detergent can be added to the further heated water that is pooled in the wash water tank 38. An example of a system for adding a wash detergent to heated water in the wash water tank 38 is disclosed in U.S. Patent No. 10,905,306 entitled Dishwasher, the entire contents of which are hereby incorporated by reference herein. It is contemplated that other means of adding a wash detergent to heated water in the wash water tank 38 can be employed.

[0037] Once the wash water is heated in the wash water tank 38 as outlined above, the wash cycle can begin. To begin the wash cycle, the drain outlet in the bottom of the wash water tank 38 opens in a first manner to allow the wash water in the wash water tank 38 to be pumped by the wash water pump 40 through the wash water conduit 42. The wash water conduit 42 includes a wash pump supply conduit path 82 that supplies wash water to the wash water pump 40, a wash water conduit path 78 that leads from the wash water pump 40 to the top rotary spray arm 16 and to the bottom rotary spray arm 18. If other means are used to spray water onto the dishes as discussed above, the further heated wash water in the wash water conduit 42 will be conduited to those other means.

[0038] After the heated wash water is sprayed by the top rotary spray arm 16 and the bottom rotary spray arm 18 onto the dishes in the interior wash space 12, the heated wash water will once again fall into the wash water tank 38 located at the bottom of the interior wash space 12. The heated wash water will collect within the wash water tank 38 and will continue to be heated by the second PTC heating element 74 before being pumped again by the wash water pump 40 through the wash water conduit 42 to be sprayed again onto the dishes in the interior wash space 12. This wash cycle will occur many times in order to completely clean the dishes.

[0039] After the wash cycle is complete, the drain outlet in the bottom of the wash water tank 38 opens in a second manner to allow the wash water in the wash water tank 38 to drain into the hot wastewater drain conduit 46. It is contemplated that the drain outlet can include a wash water drain conduit located within the drain outlet. The wash water drain conduit includes an open top region at about the same level as the open top 76 of the wash water tank 38 to allow heated wash water that is pooled above the open top of the wash water drain conduit to drain into the hot wastewater drain conduit 46 during the wash cycle.

[0040] In the illustrated example, most of the wastewater in the hot wastewater evacuation conduit 46 after the wash cycle will pass through the hot wastewater evacuation conduit 46 in the fresh water reservoir 28 and the wastewater evacuation outlet 48 at the end of the hot wastewater evacuation conduit 46. However, as shown in Figure 6 The hot wastewater evacuation conduit 46 includes a horizontal portion 86 that retains the hot wastewater within the fresh water reservoir 28. The hot wastewater evacuation conduit 46 can include a trap elbow hot water waste trap 88 just outside the fresh water reservoir 28, which includes a lower surface 90 above the horizontal portion 86. Because the lower surface 90 is above the horizontal portion 86, the hot wastewater will collect in the horizontal portion 86 in a hot wastewater pool 92, as shown in Figure 6 The hot wastewater pool 92 is replaced with additional hot wastewater from the evacuation outlet into the hot wastewater evacuation conduit 46, but the hot wastewater pool 92 maintains the same amount of wastewater in it because of the trap elbow hot water waste trap 88. The wastewater that is pushed out of the horizontal portion 86 and is pushed through the trap elbow hot water waste trap 88 exits the warewash machine through the wastewater evacuation outlet 48. The hot wastewater in the hot wastewater pool 92 exchanges heat with the fresh water in the internal fresh water holding space 58 before the fresh water is pumped to the rinse water induction heated tank system 34, as outlined above.

[0041] After the wash cycle is complete, the rinse cycle begins. The rinse cycle is identical to the wash cycle except that no wash detergent is added to the heated water. Thus, the heated fresh water to be sent to the rinse water holding tank 100 is heated by the exchange of heat through the fresh water reservoir 28 and the rinse water induction heated tank system 34, as outlined above. The heated fresh water in the rinse water induction heated tank system 34 is then pumped by the rinse water pump 32 through the rinse water conduit 36 to the top rotary spray arm 16 and the bottom rotary spray arm 18 (or other spray devices). After passing through the internal wash space 12, the heated water will collect in the wash water tank 38 to be further heated by the PTC heating element 74, as outlined above. After the heated water exits the rinse water induction heated tank system 34 or in the wash water tank 38, a rinse aid can be added to the heated water. An example of a system for adding a rinse agent to heated water is disclosed in U.S. Patent No. 10,905,306 entitled Warewashing Machine, the entirety of which is hereby incorporated by reference herein. It is contemplated that other devices for adding a rinse aid to heated water after it exits the rinse water induction heated tank system 34 or the wash water tank 38 can be employed.

[0042] During the rinse cycle, heated water is continuously pumped from the wash water tank 38 through the wash water conduit 42 to be sprayed through the top and bottom rotating spray arms 16, 18 (or other spray devices) as outlined above. After the rinse cycle is complete, the waste water is drained from the wash water tank 38 in the same manner as the waste water exits the wash water tank 38 and enters the hot waste water drain conduit 46 as outlined above, to exit the dishwasher 10 and form a hot waste water pool 92 to exchange heat within the fresh water reservoir 28 as outlined above.

[0043] In the wash and rinse cycles as outlined above, the fresh water entering the dishwasher 10 is heated in three different areas: by heat exchange with the waste water in the fresh water reservoir 28, by the rinse water induction heated tank system 34, and by the PTC heating element 74 in the wash water tank 38. However, it is contemplated that any one or only two of these three methods of heating water can be employed.

[0044] Reference numeral 10a Figures 8-12 generally designates a second embodiment of the present invention, a second embodiment of a dishwasher. Since the dishwasher 10a is similar to the dishwasher 10 previously described, like parts appearing in Figures 1-6 and Figures 8-12 are designated by the same corresponding reference numerals, except for the suffix "a" in the latter designations. The second embodiment dishwasher 10a is identical to the dishwasher 10 previously described, except that the second embodiment dishwasher 10a has a second embodiment of a rinse water induction heated tank system 200. The second embodiment rinse water induction heated tank system 200 receives rinse water from the pump conduit 66a, and the inductively heated water exits the second embodiment rinse water induction heated tank system 200 through the rinse water conduit 36a.

[0045] As Figure 13The illustrated second embodiment of the rinse water induction heated tank system 200 shown in FIG. 6 includes a base 202 having an induction coil 204 in the shape of a pancake therein. A rinse water tank 206 connected to the pump conduit 66a and the rinse water conduit 36a is located on top of the base 202. A rectangular insulated sleeve 208 surrounds the rinse water tank 206. The rinse water tank 206 can have any cross-sectional shape (e.g., circular and square) and receives heated clean water through a filter inlet pipe 210 that extends through a top surface 212 of the rinse water tank 206. The insulated sleeve 208 tightly surrounds an outer surface 214 of the rinse water tank 206 to minimize heat escaping from the heated rinse water in the rinse water tank 206. Pulsed direct current or high frequency alternating current is passed through the coil 204, thereby generating a magnetic flux and generating an electric current in the electrically conductive material of the rinse water tank 206 to directly heat the water therein. In induction heating, the magnetic flux from the coil 204 heats the electrically conductive material of the rinse water tank 206, where the metal electrically conductive material has better magnetic properties than metals having low magnetic properties or no magnetic properties. In a preferred embodiment, the rinse water tank 206 is formed of stainless steel 430 or stainless steel SUS201. Further, in a preferred embodiment, a rinse aid is added to the water after it exits the rinse water induction heated tank system 200 to avoid corrosion in the rinse water tank 206 due to the rinse aid chemicals.

[0046] While specific preferred embodiments of the application have been disclosed in detail herein for purposes of illustration, it will be understood by those skilled in the art that variations or modifications of the disclosed apparatus, including rearrangement of parts, are within the scope of the present application. For example, it is contemplated that only a single rotating spray arm (upper or lower) can be used.

Claims

1. A dishwashing machine, comprising: The housing has an internal washing space for washing dishes; A liquid inlet for adding clean water to the dishwashing machine; A liquid outlet for removing dirty liquid from the dishwashing machine; A first water tank for receiving water entering the housing through the liquid inlet, the first water tank including a first heating system for heating the water to form heated water; A first conduit is used to deliver the heated clean water to at least one spray nozzle so as to spray the heated clean water onto the tableware positioned within the internal washing space; A second water tank is configured to receive the heated clean water from the internal washing space, the second water tank including a second heating system for heating the heated clean water to form heated washing water; as well as A second conduit is used to deliver the heated wash water to the at least one spray nozzle so as to spray the heated wash water into the internal washing space. In this system, at least one of the first heating system and the second heating system heats the water by induction.

2. The dishwashing machine according to claim 1, further comprising: A clean water reservoir for receiving clean water from the liquid inlet therein, the clean water in the clean water reservoir being configured to be heated to form initially heated clean water, and a first water tank receiving the initially heated clean water from the clean water reservoir; and A discharge conduit for delivering the heated wash water from the second water tank through the clean water reservoir and to the liquid outlet, the discharge conduit transferring heat from the heated wash water to the clean water in the clean water reservoir to form the initially heated clean water.

3. The dishwashing machine according to claim 2, wherein: The discharge conduit includes a horizontal portion within the clean water reservoir and a curved hot water waste trap just outside the clean water reservoir. The curved hot water waste trap includes a lower surface above the horizontal portion to allow the heated wash water to collect in the horizontal portion.

4. The dishwashing machine according to claim 2, further comprising: A pump for pumping the initially heated clean water from the clean water reservoir to the first water tank, and for pumping the heated clean water from the first water tank to the at least one spray nozzle.

5. The dishwashing machine according to claim 1, wherein: The at least one spray nozzle is a plurality of spray nozzles located on the top rotating arm and the bottom rotating arm.

6. The dishwashing machine according to claim 1, further comprising: A first pump is used to pump the heated clean water from the first water tank to the at least one spray nozzle; as well as A second pump is used to pump the heated wash water from the second water tank to the at least one spray nozzle.

7. The dishwashing machine according to claim 1, wherein: At least one of the first heating system and the second heating system includes a stainless steel shell having a positive temperature coefficient heating array therein, the positive temperature coefficient heating array including a plurality of positive temperature coefficient heating elements, wherein a temperature sensor is connected to the heater cover to measure the temperature of the first heating system to maintain the temperature of the first heating system below a predetermined temperature.

8. The dishwashing machine according to claim 1, wherein: At least one of the first heating system and the second heating system that heats water by induction includes a first water tank, an insulation cylinder surrounding the first water tank, and an induction coil coiled around the insulation cylinder, the coil receiving an electric current therethrough to heat the water in the first water tank.

9. The dishwashing machine according to claim 1, wherein: At least one of the first heating system and the second heating system that heats water by induction includes a first water tank, a base having an induction coil in the shape of a pancake therein, and a rectangular heat-insulating sleeve surrounding the first water tank, wherein the first water tank is positioned on top of the base, and wherein the coil receives current passing through it to heat the water in the first water tank.

10. A method for washing dishes, comprising: Provides a housing with an internal washing space for receiving tableware; Add clean water to the dishwashing machine; The clean water is delivered to the first water tank; The first heating system is used to heat the clean water in the first water tank to form heated clean water; The heated clean water is supplied to at least one spray nozzle; The heated water is sprayed onto the tableware positioned within the internal washing space; The heated clean water is delivered from the internal washing space to the second water tank; The heated water in the second water tank is heated using a second heating system to form heated washing water; The further heated washing water is delivered to the at least one spray nozzle; as well as The heated washing water is sprayed into the internal washing space; In this system, at least one of the first heating system and the second heating system heats the water by induction.

11. The method of claim 10, further comprising: A pump is used to pump the heated clean water from the first water tank to the at least one spray nozzle.

12. The method according to claim 10, wherein: The at least one spray nozzle is a plurality of spray nozzles located on the top rotating arm and the bottom rotating arm.

13. The method of claim 10, further comprising: The clean water is supplied to the clean water storage tank; The water in the water reservoir is heated to form initially heated water; as well as The further heated wash water is discharged through a drain pipe passing through the clean water reservoir and discharged to the liquid outlet.

14. The method of claim 13, wherein: The discharge conduit includes a horizontal portion within the clean water reservoir and a curved hot water waste trap just outside the clean water reservoir. The curved hot water waste trap includes a lower surface above the horizontal portion to allow the further heated wash water to collect in the horizontal portion.

15. The method of claim 10, further comprising: The heated clean water is pumped from the first water tank to the at least one spray nozzle using a first pump; as well as A second pump is used to pump the further heated wash water from the second water tank to the at least one spray nozzle.

16. The method of claim 10, wherein: At least one of the first heating system and the second heating system includes a stainless steel shell having a positive temperature coefficient heating array therein, the positive temperature coefficient heating array including a plurality of positive temperature coefficient heating elements, wherein a temperature sensor is connected to the heater cover to measure the temperature of the first heating system to maintain the temperature of the first heating system below a predetermined temperature.

17. The method of claim 10, wherein: At least one of the first heating system and the second heating system that heats water by induction includes a first water tank, an insulation cylinder surrounding the first water tank, and an induction coil coiled around the insulation cylinder, the coil receiving an electric current therethrough to heat the water in the first water tank.

18. The method of claim 10, wherein: At least one of the first heating system and the second heating system that heats water by induction includes a first water tank, a base having an induction coil in the shape of a pancake therein, and a rectangular heat-insulating sleeve surrounding the first water tank, wherein the first water tank is positioned on top of the base, and wherein the coil receives current passing through it to heat the water in the first water tank.

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