CN109068931B

CN109068931B - Washing machine with improved long-term reliability and safety

Info

Publication number: CN109068931B
Application number: CN201680084904.4A
Authority: CN
Inventors: F·P·安德森; M·弗列格利斯; J·安妮罗
Original assignee: Electrolux Appliances AB
Current assignee: Electrolux Appliances AB
Priority date: 2016-04-26
Filing date: 2016-04-26
Publication date: 2021-09-28
Anticipated expiration: 2036-04-26
Also published as: WO2017186279A1; AU2016405231B2; EP3448221B1; PL3448221T3; AU2016405231A1; CN109068931A; AU2017202646A1; PL3238599T3; EP3238599A1; TR201904090T4; AU2017202646B2; EP3448221A1; EP3238599B1

Abstract

The invention relates to a heating unit (8) for a washing machine (1), comprising a housing (22), a pump (20) for pumping washing liquid through the housing (22), a fuse (36), a heat-conducting element (30) for transferring heat to the washing liquid in the housing (22), and a temperature regulator (34) which is capable of supplying energy in the form of heat to the heat-conducting element (30) when a target temperature of the washing liquid in the housing (22) is below a first temperature limit. The fuse (36) and the temperature regulator (34) are arranged for heat conduction with the heat conducting element (30), the fuse (36) being electrically connected to the temperature regulator (34) and configured to trigger and stop the supply of energy to the temperature regulator (34) when the washing liquid in the housing (22) reaches a trigger temperature of the fuse (36). The heating unit (8) comprises an electronic temperature sensing device (38) electrically connected to the fuse (36) and the thermostat (34), said electronic temperature sensing device (38) being arranged for conducting heat with the heat conducting element (30) and for detecting and recording over time the temperature of the washing liquid passing through the casing (22) so as to provide information about the operating state of the washing machine.

Description

Washing machine with improved long-term reliability and safety

Technical Field

The present invention relates to the field of washing machines, in particular dishwashers and their improved safety and long-term reliability. In particular, the invention relates to improving the protective monitoring of a washing machine over time and to improving the safety of fuses in a heating unit. The washing machine according to the invention allows to reduce the service invocation rate and thus the costs for operating the washing machine while at the same time improving the reliability.

Background

Dishwashers have been in use for many years and operate under harsh conditions sometimes with heavy soil and sometimes aggressive wash liquor. The wash liquor is typically a mixture of detergent, water, and food/waste residue. Dishwashers typically include a cleaning receptacle including one to several spray arms that rotate when the dishwasher is in use. Typically, water is supplied via an inlet valve connected to a fresh water pipe (typically tap water) and an outlet valve for used wash liquor, the outlet valve being connected to a waste water pipe. The wash liquid is pumped by a pump through a wash liquid distribution system that includes a number of conduits and partitions that direct wash liquid to spray arms for spraying the dishes in the container. The washing liquid spray is then typically collected in a hole, typically funnel-shaped, at the bottom of the container and from there the washing liquid is pumped again into the washing liquid distribution system. In order to ensure that the washing liquid has a suitable temperature so that maximum cleaning effect can be achieved, the thermostat is usually connected to a housing accommodating the pump, so that at least a part of the housing supplies energy in the form of heat to the washing liquid in the pump. Since the energy supplied to the thermostat and thus at least a part of the housing is considerable, a safety mechanism is used. The known safety mechanism comprises a fuse arranged on the housing and configured to be triggered when the fuse reaches a trigger temperature. When the fuse triggers, the energy supply to the thermostat is interrupted and stopped. Thus, the task of the fuse is to avoid starting to boil the wash liquor and overheating the dishwasher, which may cause several electrically unsafe conditions and in the worst case a fire.

The entire unit, usually with a thermostat and a pump, needs to be replaced after the fuse is triggered, which requires the user to call a technician and thus increases the service call rate of the washing machine and dishwasher, respectively.

In some cases, triggering a fuse is desirable and should occur, for example, when a pump fails or breaks. However, the fuse may be triggered in other situations, for example when the dishwasher is very dirty, when the filter is clogged, when raw eggs are somehow put into the machine, when excessive limestone is deposited in the dishwasher, when considerable dishes are turned over and block the travel path of the washing liquid, or when the wrong detergent is used (e.g. hand dishwashing detergent causing a lot of foam). Today, for any of the above accidents, a technician must be called up and the unit must be replaced, as the thermostat and fuse are usually fixedly connected to the housing of the pump. This is expensive for the user and increases the service usage, which many manufacturers of washing machines try to reduce.

DE 102013217276 a1 shows a dishwasher comprising a heating device, in particular a heating pump for heating the washing liquid passing through the pump. The object of DE 102013217276 a1 is to provide a dishwasher which can detect the risk of overheating before the dishwasher becomes too hot. It is proposed to detect overheating via two resistance thermometers arranged one after the other in the direction of flow of the washing liquid. Two resistance thermometers measure the temperature of the washing liquid outside the pipe, wherein the limestone suction zone is arranged inside the pipe, just on the other side of the two resistance thermometers. By determining the temperature difference between the two resistance thermometers it is possible to detect how much limestone is present on the limestone suction area and to detect if this is a problem and thus to find if the machine needs cleaning.

Although DE 102013217276 a1 can detect the deposition of limestone in a dishwasher, it is not possible to prevent the triggering of a fuse in the event that overheating is not associated with limestone deposition. Thus, in DE 102013217276 a1, any of the above-mentioned faults related to clogged filters, turned dishes, eggs, wrong detergent, etc., will trigger a fuse.

Fuses and thermostats typically use bimetallic sensors for temperature regulation and also for triggering the fuse. Thus, these sensors are neither electronic nor digital and do not allow monitoring of the temperature of the washing liquid over time.

Disclosure of Invention

In view of the above, the inventors of the present invention have found that it is possible to prevent the above described malfunction triggering fuse and thus require a technician to replace the heating unit.

It is an object of the present invention to provide a washing machine having improved reliability, being easy to maintain, and allowing problems related to the heating unit and/or the pump to be corrected before any of them needs to be replaced.

It is still another object of the present invention to provide a washing machine which prevents a fuse from being triggered due to overheating.

It is another object of the present invention to provide a method of operating a washing machine so as to reduce the risk of overheating the triggering fuse.

The washing machine may in particular be a dishwasher.

The above object is achieved by a heating unit for a washing machine as claimed in claim 1, and by a method for controlling a heating unit as claimed in claim 13.

A heating unit for a washing machine is disclosed herein, the heating unit comprising a housing, a pump for pumping washing liquid through the housing, a fuse, a heat conducting element for transferring heat to washing liquid in the housing, and a temperature regulator capable of supplying energy in the form of heat to the heat conducting element when a target temperature of washing liquid in the housing is below a first temperature limit. The fuse and the temperature regulator are arranged for conducting heat with the heat conducting element, the fuse being electrically connected to the temperature regulator and configured to trigger and stop the supply of energy to the temperature regulator when the washing liquid in the housing reaches a trigger temperature of the fuse. The heating unit further comprises an electronic temperature sensing device arranged for conducting heat with the heat conducting element and for detecting and recording the temperature of the washing liquid passing through the housing over time in order to provide information about the state of the washing machine.

Further disclosed herein is a method of controlling a heating unit of a washing machine, the method comprising the steps of:

-pumping washing liquid through the heating unit and thereby heating the washing liquid,

-controlling and regulating the temperature of the washing liquid with a temperature regulator such that the temperature of the washing liquid is not lower than a first given temperature limit,

-stopping the energy supply to the thermostat by triggering a fuse electrically connected to the thermostat when the washing liquid in the housing reaches the triggering temperature of the fuse, and

-detecting and recording the temperature of the washing liquid passing through the casing over time via electronic temperature sensing means in order to provide information about the operating state of the washing machine.

Thus, the electronic temperature sensing device is configured to supply information about the physical and/or operating state of the washing machine, so that the user interface of the washing machine can inform the user that a cleaning program needs to be run. The supplier of the washing machine may also use this information, for example, to send a machine cleaning pack directly to the user upon receiving information that the machine requires cleaning.

The electronic temperature sensing device may be a single electronic temperature sensing device.

For cost and simplicity reasons, a preferred embodiment of the above-described heating unit may comprise a single temperature sensing device. However, it is conceivable that the heating unit comprises a plurality of (single) temperature sensing means.

The temperature sensing device is configured to sense an absolute temperature of the wash liquid.

The electronic temperature sensing device may be a digital electronic temperature sensor.

While the electronic temperature sensing device may be directly electrically connected to the fuse and the thermostat, electrical communication may alternatively be directed via a controller (e.g., a processor of a user interface of the washing machine).

In an embodiment, the electronic temperature sensing device may be electrically connected to the fuse and the temperature regulator, said temperature sensing device may be configured to stop the supply of energy to the temperature regulator when the temperature of the washing liquid in the housing reaches a second temperature limit, wherein the second temperature limit is lower than the trigger temperature of the fuse.

This may help to protect the fuse from being triggered and may thus give the user the opportunity to clean the machine and thus to restore the normal operating state of the washing machine. Further, inspection and repair by technicians may be avoided, which saves time, effort, and cost to the user.

Stopping the supply of energy to the thermostat may be accomplished directly through the electronic temperature sensing device, or may be communicated via a processor (e.g., via a user interface).

In an embodiment, the electronic temperature sensing device may be configured to electrically connect to a water inlet valve of the washing machine such that water inlet valve may be opened when the electronic temperature sensing device detects that a wash liquid temperature gradient in the housing exceeds a gradient limit in order to avoid triggering of the fuse.

Sensing the temperature gradient in the wash liquid over time can help prevent overcooking effects. For example, when something is boiled in a pan on a stove (not a gas stove) and then it boils, the user turns off the heating plate but the temperature in the pan continues to rise, an overcooking effect occurs, causing water and foam to overflow the edges of the pan, while the (still hot) heating plate is turned off.

A water inlet valve may be opened via a processor of a user interface or via direct electrical communication between the temperature sensing device and the water inlet valve.

In the case of direct communication between the inlet valve, thermostat and/or fuse and the electronic temperature sensing device, the processor may be integrated in the electronic temperature sensing device.

The effect of the above-mentioned suggestion that the water inlet valve is opened may be that the washing liquid cools down rapidly to avoid triggering a fuse due to overcooking after stopping the energy supply.

In another embodiment, the electronic temperature sensing device may be configured to send information about the operating state of the washing machine to a storage medium for extraction and/or analysis.

The water inlet valve may also be opened to cool the heating unit and thus the fuse independently of the detected temperature gradient.

Different steps can be taken on the basis of this data, for example by the supplier of the cleaning products for the washing machine. This information can even be used to improve future development of the washing machine.

The temperature sensing means may be positioned in the range of 0-30mm, preferably 0-25mm, more preferably 0-20mm, more preferably 0-15mm, even more preferably 0-10mm, and even more preferably 0-5mm from the fuse. The temperature sensing device may be positioned at the fuse.

The above minimizes the difference between the temperature at the fuse and the temperature sensing device and thus improves reliability.

In an embodiment, the temperature sensing device may be configured to measure the temperature of the washing liquid via the fuse.

Directly sensing the temperature at the fuse may provide a very accurate temperature of the fuse.

Alternatively, the temperature sensing device may be configured to measure the temperature of the washing liquid via the heat conducting element.

Sensing the temperature at the thermally conductive element can deliver more accurate wash liquor temperature information over time.

The heat conducting element may be a cover of a housing configured to receive at least a portion of a pump of the washing machine.

In a preferred embodiment, the second temperature limit may be about 2 ℃ to 15 ℃, preferably 4 ℃ to 12 ℃, more preferably 5 ℃ to 10 ℃, more preferably 6 ℃ to 10 ℃, and even more preferably 7 ℃ to 9 ℃ below the trigger temperature of the fuse.

The temperature difference between the trigger temperature of the fuse and the second temperature limit may ensure that the fuse is not triggered until the cleaning solution reaches the second temperature limit.

The heating unit may be optimized for use in a dishwasher.

Further disclosed herein is a dishwasher comprising a heating unit according to any of the above embodiments.

The method according to the previous embodiment may further comprise the steps of:

-measuring the temperature gradient of the washing liquid by means of the electronic temperature sensing means,

-detecting whether the wash liquid temperature gradient in the housing exceeds a gradient limit, and

-opening a water inlet valve by sending a signal from the electronic temperature sensing device to the water inlet valve when the temperature sensing device detects that the temperature increase exceeds the gradient limit, in order to avoid the fuse triggering.

As mentioned before, this will prevent the fuse from triggering due to an overcooking effect, in which the temperature of the washing liquid is still increasing even after stopping the energy supply to the thermostat, for example because the heat-conducting element is still hot and thus continues to heat the washing liquid (at least for a short time).

Drawings

The invention will now be described in more detail, by way of example only, and with reference to the accompanying drawings, in which:

FIG. 1 schematically illustrates a front side perspective view of a dishwasher;

FIG. 2 schematically illustrates a cross-sectional view of the dishwasher through dashed line II of FIG. 1;

FIG. 3a shows a top down view of an embodiment of a heating unit according to the invention;

FIG. 3b illustrates a top down view of another embodiment of a heating unit according to the present invention;

FIG. 4 illustrates a front side view of an embodiment of the heating unit according to FIG. 3 b; and is

Fig. 5 illustrates a method for controlling a heating unit according to the invention.

Detailed Description

The invention is explained and partially illustrated herein by way of example of a dishwasher 1 as shown in fig. 1 and 2, but other washing machines, such as a washing machine, may also fall within the scope of the invention.

Fig. 1 shows a perspective view of a dishwasher 1 with a container 6, a door 16 for opening when dishes need to be placed in the dishwasher 1 or when dishes need to be removed from the dishwasher. Dishwasher 1 comprises two drawers 18 ', 18 ", an upper drawer 18' and a lower drawer 18". Drawers 18', 18 "are used for convenient placement and removal of the dishes and to hold the dishes in place during washing. The dishwasher further comprises a washing liquid distribution arrangement 4 comprising a spray arrangement 14 having at least two rotating spray arms 14a, 14b, a rotating upper spray arm 14a and a rotating lower spray arm 14 b. After being sprayed onto the dishes, the washing liquid is collected in a funnel-shaped drain 13 arranged at the bottom of the container 6, so that it can be heated again in the heating unit 8 (see fig. 3a to 4) for another spraying cycle. The wash liquor distribution arrangement 4 is further illustrated in fig. 2. The door 16 includes a container 9 for receiving detergent and a cover 11 for closing the container 9. The lid 11 is configured to be opened once the dishwasher 1 has finished rinsing the dishes and detergent is needed for further cleaning.

The dishwasher 1 shown in fig. 1 may further comprise a user interface 10 comprising a display 24 and a number of buttons 26. The user interface 10 may be configured to show the user the status of the machine, the washing program selected, and whether cleaning of the machine is required. The user interface 10 may further include a communication interface for communicating with a network, or the user interface may include a storage medium (not shown) for storing information in the form of data. The user interface 10 may further include a controller or processor.

Turning now to fig. 2, this shows a cross-sectional view of the dishwasher 1 according to fig. 1 in use and with the door 16 closed, wherein the cross-section is cut along the dashed line II of fig. 1. The container 6 or closed space is shown from the side and shows a lower drawer 18 "and an upper drawer 18'. Lower 14b and upper 14a rotary spray arms are also shown. The example of fig. 2 shows two rotating spray arms 14a, 14b, however, there may be more than two rotating spray arms or only a single rotating spray arm. The same except for the possibility of an upper drawer and a lower drawer, there may be more than two drawers or only a single drawer in the dishwasher 1. In particular, special drawers for cutlery may be installed. The upper spray arm 14a and the lower spray arm 14b are part of the washing liquid distribution arrangement 4. The washing liquid distribution arrangement 4 comprises a partition 12, e.g. a three-way valve, for supplying washing liquid to the upper and lower spray arms 14a, 14b, a number of pipes 15 for guiding the washing liquid, and a funnel-shaped drain 13. To limit the amount of dirt entering the wash liquor distribution system, a screen 42 is provided at the top of the funnel-shaped drain opening 13. The drain 13 collects the washing liquid present in the container 6, which is illustrated by the washing liquid level illustrated with reference numeral 19 in fig. 2.

Fresh or tap water is supplied to the dishwasher via an inlet 2 which includes a water inlet valve 40. The water inlet valve 40 is electrically connected to a controller or processor (not shown) of the dishwasher 1 so that the water inlet valve 40 can be opened and closed when the controller or processor gives a corresponding signal. The controller or processor may be integrated behind the user interface 10 or behind the buttons 26 or display, for example. The controller or processor may be located in any suitable location in dishwasher 1 as long as the controller or processor is connected to buttons 26, display 24, and heating unit 8. Thus the waste water as well as the used washing liquid is treated via the waste water outlet 3, which comprises a non-return valve 41. The non-return valve 41 ensures that the waste water, once treated, cannot enter the dishwasher again.

Still referring to fig. 2, the heating unit 8 is integrated in the washing liquid distribution arrangement 4. The heating unit 8 may be positioned in any suitable location in the washing liquid distribution arrangement 4 and is shown in fig. 2 to be positioned more or less directly after the drain opening 13.

Referring now to fig. 3a to 4, the heating unit 8 will be explained in more detail.

Fig. 3a shows a top-down view of a heating unit 8 according to the invention. The heating unit 8 comprises a housing 22 for receiving the pump 20, as shown in fig. 4. Referring to fig. 3a, the housing 22 includes a thermally conductive element 30, which is illustrated as a cover of the housing 22. The heat conducting element 30 is made of a heat conducting material (e.g. metal). Although the thermally conductive element 30 is shown as a cover of the housing 22, the thermally conductive element need not be a cover of the housing 22. It is conceivable to provide a heat conducting element (not shown) which is any other part of the housing 22 or a separate part protruding into the housing 22 for contacting the washing liquid and thus for heating the washing liquid in the housing 22.

The thermally conductive element 30 includes a temperature regulator 34, a fuse 36, and an electronic temperature sensing device 38. The electronic temperature sensing device 38 is preferably capable of recording data over time. The temperature regulator 34 comprises a thermostat and is configured to supply energy in the form of heat to the heat conducting element 30 to heat the washing liquid pumped through the casing 22 when the temperature of the washing liquid is below the first temperature limit. The temperature regulator senses the temperature of the washing liquid via the heat conducting element 30. The fuse 36 is configured to trigger when the cleaning solution and thus when the fuse 36 reaches a temperature that exceeds the trigger temperature of the fuse 36. The first temperature limit is below the trigger temperature of the fuse 36, preferably 5-20 deg.C below, more preferably 8-17 deg.C below, and even more preferably 10-15 deg.C below. When the fuse 36 is triggered, the energy supply to the thermostat 34 is cut off as a safety measure, for example when there is too much air in the system and/or when the washing liquid starts to boil. Because there is communication between the fuse 36 and the temperature sensing device 34, the energy supply can be cut off directly by leading the power supply via the fuse 36 to the thermostat 34, for example by separating conductors and thus by creating a physical interruption, the power supply will be cut off once the fuse 36 is triggered, or the energy supply can be cut off digitally via a controller or processor of the dishwasher 1.

The electronic temperature sensing device 38, the thermostat 34, and the fuse 36 are electrically interconnected and also connected to the controller or processor of the dishwasher for control purposes. As shown in fig. 3a and 3b, the electrical connection of the controller or processor of the dishwasher 1 may be accomplished, for example, via electrical terminals 32. The electronic temperature sensing device 38 detects and records the temperature of the wash liquor over time during the wash cycle and stores this recorded data on a storage medium via a controller or processor. The technician may extract this data from the storage medium or alternatively the storage medium sends the data directly to the server via the communication module and the world wide web. The data can then be analyzed and it determined what type of action should be taken.

The fuse 36 and the temperature regulator 34 are connected to the heat conducting element 30 via a metal plate 44 (refer to fig. 4), preferably an aluminum plate.

The temperature sensing means 38, in addition to the function of recording temperature data of the washing liquid via the heat conducting element 30, also has the task of protecting the fuse 36 from being triggered for unnecessary reasons, thus when the dishwasher 1 is too dirty and needs cleaning or when other "easy to repair" problems occur, such as a turned-over container interrupting the flow of washing liquid in the dishwasher 1. The electronic temperature sensing device 38 is configured to stop the supply of energy to the thermostat 34 in the event that it detects that a second temperature limit is reached, which is lower than the trigger temperature of the fuse 36 but higher than the first temperature limit. Thus, triggering of the fuse 36 may be prevented by the electronic temperature sensing device 38. This may be done via communication between the controller/processor of the dishwasher 1 and an electronic temperature sensing device 38 which, upon detecting that the second temperature limit has been reached, sends a signal to the controller, wherein the controller then stops the supply of energy to the thermostat 34 in order to protect and prevent the fuse 36 from triggering. Stopping the supply of energy to the thermostat 34 may also be accomplished directly between the electronic temperature sensing device 38 and the thermostat 34, however, this may require another controller or microprocessor to be located somewhere between the electronic temperature sensing device 38 and the thermostat 34.

In an embodiment, the electronic temperature sensing device 38 may also be configured for sensing a temperature gradient of the wash liquid and for detecting whether this temperature gradient is below or above a gradient limit. The electronic temperature sensing device 38 can also shut off the energy supply by sending a corresponding signal to the controller in order to protect the fuse 36 if the temperature gradient of the wash liquor exceeds the gradient limit. This can prevent the fuse 36 from triggering since heat can be supplied even after the power supply to the temperature regulator 34 is disconnected. As an emergency measure for cooling the fuse 36, the controller may even open the water inlet valve 40 (fig. 2) to cool the heating unit 8 and thus the fuse 36 upon receiving a corresponding signal from the electronic sensing device 38. The water or tap water entering the dishwasher 1 from the inlet 2 is typically cold and thus below 20 ℃ and allows a rather fast cooling of the heating unit 8.

Upon receiving a signal from the electronic temperature sensing means 38 that the washing liquid has reached the second temperature limit, the controller may display a message to the user on the display 24 that the dishwasher 1 should be cleaned by using the cleaning program and/or the detergent.

The electronic temperature sensing device 38 can measure the temperature of the cleaning solution passing through the fuse 36, and thus, the temperature of the fuse 36. Alternatively, the electronic temperature sensing device 38 may measure the temperature of the wash liquid via the heat conducting element 30. In both cases, it is advantageous to locate the electronic temperature sensing device 38 as close as possible to the fuse 36. Fig. 3a shows that the electronic temperature sensing means 38 is positioned at a small distance from the fuse 36, wherein small means about 0-10mm, preferably 0-5 mm. On the other hand, FIG. 3b illustrates that the electronic temperature sensing device 38 can be positioned directly at the fuse 36 or in close proximity to the fuse 36.

In an embodiment (not shown), the electronic temperature sensing device 38 may be integrated into the fuse 36.

Fig. 3a and 3b further illustrate the ground contact 46, the pump inlet 48, and the pump outlet 50. Wash liquid enters the housing 22 via the pump inlet 48 and exits the housing 22 via the pump outlet 50. During the actual pumping, the washing liquid is heated by the heat-conducting element 30.

The thermally conductive element 30 is connected to the lower portion of the housing 22 via a fastening mechanism 52 that includes a plurality of latches and catches 54 that engage with a flange of the lower portion of the housing 22. However, other forms of fastening mechanisms 52 may be employed, such as a threaded or other form of mating solution. The lower portion of the housing 22 may be made of a polymer or the like, however, any other suitable material may be used.

Fig. 4 shows a side view of the heating unit 8 and the pump 20, which comprises a pump motor 20b, a pump rotor 20a, which is shown in dashed lines since it is theoretically not visible through the housing 22. The pump motor 20b is configured for connection to the housing 22 and the pump rotor 20a, wherein the pivot shaft 20c, which is rotatably connected to the pump motor 20b, is configured for engaging the pump rotor 20 a. In fig. 4, the ground contact 46 is omitted.

As can be seen, a fuse 36, a thermostat 34, and an electronic temperature sensing device 38 are disposed on the metal plate 44. These may be glued, soldered, welded, or screwed to the metal plate 44. Mechanical clips for attaching the thermostat 34, fuse 36, and electronic temperature sensing device 38 to the board 44 may also be used. Of course, each of the thermostat 34, fuse 36, and electronic temperature sensing device 38 may be secured to the metal plate 44 in a different manner.

In fig. 4, the pump inlet 48 and pump outlet 50 are also visible.

Turning now to fig. 5, this figure illustrates a method of controlling a heating unit of a washing machine, in particular of a dishwasher 1, comprising the steps of:

pumping the washing liquid through the heating unit 8 and thereby heating the washing liquid at step S01,

controlling with the thermostat 34 in step S02 and adjusting the temperature of the washing liquid in step S03 such that the temperature of the washing liquid is not lower than a first given temperature limit,

-detecting and recording the temperature of the washing liquid passing through the casing 22 over time via the electronic temperature sensing means 38 in step S04 in order to provide information about the operating state of the washing machine, and

Cut off the energy supply to the thermostat 34 by triggering the fuse 36 electrically connected to the thermostat 34 at step S07b when the electronic temperature sensing means 38 detects that the washing liquid in the housing 22 reaches the trigger temperature of the fuse 36 at step S07 a.

The method may further comprise the steps of: the supply of energy to the thermostat 34 is stopped at step S05b, wherein the electronic temperature sensing device 38 sends a signal to the thermostat 34 when the electronic temperature sensing device 38 detects that the temperature of the wash liquid in the housing 22 reaches a second temperature limit at step S05a, wherein the second temperature limit is lower than the trigger temperature of the fuse 36 but higher than the first temperature limit.

The method may further comprise the steps of:

measuring the temperature gradient of the washing liquid by means of the electronic temperature sensing means 38 at step S04,

-detecting in step S05a whether the temperature gradient of the washing liquid in the housing 22 exceeds a gradient limit, and

opening the water inlet valve 40 by sending a signal from the electronic temperature sensing device 38 to the water inlet valve 40 in step S06 when the electronic temperature sensing device 38 detects a temperature increase exceeding the gradient limit in order to avoid triggering of the fuse 36.

The water inlet valve 40 may also be opened if the temperature of the wash liquid is detected to exceed the second temperature limit. Thus, even if the gradient of the temperature of the wash liquid is detected to be below the gradient limit, the water inlet valve 40 may be opened by sending a signal from the electronic temperature sensing device 38.

The difference between cutting off the energy supply and stopping the energy supply at step S07b is that the cut-off is preferably a physical interruption of the electrical power, which cut-off is created by the triggered fuse 36, whereas the stop at step S05b may be an electronic interruption of the electrical power. The electrical interruption may be addressed when cleaning the dishwasher 1, whereas the physical interruption may only be addressed by a technician, who replaces the heating unit 8. Corresponding information may be displayed to the user via the display 24 at step S08.

The method may further include transmitting information regarding the operational status of the washing machine to a storage medium for extraction and analysis.

As mentioned before, the above-described heating unit 8 and method may be implemented in any suitable washing machine (e.g. also a washing machine).

As previously mentioned, the heating unit 8 may comprise only one single temperature sensing device 38. However, a plurality of temperature sensing devices (not shown) may be mounted on the heating unit in order to provide redundancy.

The positioning of the electronic temperature sensing device 38 can vary anywhere on the housing 22 so long as the electronic temperature sensing device can safely detect the temperature of the wash liquid in the housing 22 and is electrically connected to the thermostat 34, the fuse 36, and the controller or processor of the washing machine.

Claims

1. A heating unit (8) for a washing machine (1), comprising a housing (22), a pump (20) for pumping washing liquid through the housing (22), a fuse (36), a heat-conducting element (30) comprising a temperature regulator (34) and arranged for transferring heat to washing liquid in the housing (22), the temperature regulator (34) being capable of supplying energy in the form of heat to the heat-conducting element (30) when a target temperature of washing liquid in the housing (22) is below a first limit temperature, wherein the fuse (36) and the temperature regulator (34) are arranged for conducting heat with the heat-conducting element (30), the fuse (36) being electrically connected to the temperature regulator (34) and being configured for triggering and stopping the supply of energy to the temperature regulator (34) when the washing liquid in the housing (22) reaches a triggering temperature of the fuse (36),

characterized in that the heating unit (8) comprises an electronic temperature sensing device (38) arranged for conducting heat with the heat conducting element (30) and for detecting and recording the temperature of the washing liquid passing through the housing (22) via the heat conducting element (30) over time in order to provide information about the temperature gradient of the washing liquid, the electronic temperature sensing device (38) also being capable of cutting off the energy supply to protect the fuse (36) by sending a corresponding signal to a controller if the temperature gradient exceeds a gradient limit.

2. The heating unit according to claim 1, wherein the electronic temperature sensing device (38) is electrically connected to the fuse (36) and the temperature regulator (34), said electronic temperature sensing device (38) being configured to stop the supply of energy to the temperature regulator (34) when the temperature of the washing liquid in the housing (22) reaches a second limit temperature, wherein the second limit temperature is lower than the trigger temperature of the fuse (36).

3. Heating unit according to claim 1, wherein the electronic temperature sensing device (38) is configured for being electrically connected to a water inlet valve (40) of the washing machine (1) such that the water inlet valve (40) can be opened when the electronic temperature sensing device (38) detects that a washing liquid temperature gradient in the housing (22) exceeds a gradient limit, in order to avoid triggering of the fuse (36).

4. The heating unit according to any one of the preceding claims 1-3, wherein the electronic temperature sensing means (38) is configured to send information about the washing liquid temperature gradient to a storage medium for analysis.

5. The heating unit according to any one of the preceding claims 1-3, wherein the temperature sensing device (38) is positioned in the range of 0-30mm from the fuse (36).

6. The heating unit according to claim 5, wherein the temperature sensing device (38) is positioned in the range of 0-20mm from the fuse (36).

7. The heating unit according to claim 6, wherein the temperature sensing device (38) is positioned in the range of 0-10mm from the fuse (36).

8. The heating unit according to any one of the preceding claims 1-3, wherein the temperature sensing device (38) is positioned at the fuse (36).

9. Heating unit according to any one of the preceding claims 1-3, wherein the heat conducting element (30) is a cover of the housing (22).

10. The heating unit according to claim 2, wherein the second limit temperature is 2 ℃ to 15 ℃ lower than the trigger temperature of the fuse (36).

11. The heating unit according to claim 10, wherein the second limit temperature is 4 ℃ to 12 ℃ lower than the trigger temperature of the fuse (36).

12. The heating unit according to claim 11, wherein the second limit temperature is 6 ℃ to 10 ℃ lower than the trigger temperature of the fuse (36).

13. The heating unit according to any of the preceding claims 1-3, wherein the heating unit is configured for use in a dishwasher.

14. A dishwasher comprising a heating unit according to any one of claims 1 to 13.

15. A method of controlling a heating unit of a washing machine according to claim 1, the method comprising the steps of:

-controlling and regulating the temperature of the washing liquid with a temperature regulator (34) such that the temperature of the washing liquid is not lower than a first limit temperature,

-cutting off the energy supply to the thermostat (34) by activating a fuse (36) electrically connected to the thermostat (34) when the washing liquid in the housing (22) reaches the activation temperature of the fuse (36),

it is characterized in that the preparation method is characterized in that,

-detecting and recording the temperature of the washing liquid passing through the housing (22) via the heat conducting element (30) over time via the electronic temperature sensing means (38) to provide information about the washing liquid temperature gradient, detecting whether the washing liquid temperature gradient exceeds a gradient limit, and shutting off the energy supply to protect the fuse by sending a corresponding signal to the controller when the washing liquid temperature gradient exceeds the gradient limit.

16. The method of claim 15, comprising the steps of:

-stopping the supply of energy to the thermostat (34) when the electronic temperature sensing means (38) detects that the temperature of the washing liquid in the housing (22) reaches a second limit temperature, wherein the electronic temperature sensing means (38) sends a signal to the thermostat (34), wherein the second limit temperature is lower than the trigger temperature of the fuse (36).

17. The method according to claim 15 or 16, comprising the steps of:

-measuring the temperature gradient of the washing liquid by means of the electronic temperature sensing means (38),

-detecting whether the wash liquid temperature gradient in the housing (22) exceeds a gradient limit, and

-opening the water inlet valve (40) by sending a signal from the electronic temperature sensing device (38) to the water inlet valve (40) when the electronic temperature sensing device (38) detects a temperature increase exceeding the gradient limit, in order to avoid triggering of the fuse (36).

18. The method according to claim 15 or 16, wherein the washing machine is a dishwasher.

19. The method according to claim 15 or 16, comprising the steps of:

-sending information about the washing liquid temperature gradient of the washing machine to a storage medium for analysis.