JPH0824196A - Dish washing machine - Google Patents

Abstract

PURPOSE:To rapidly detect a heating condition of a PTC heater for producing hot air for drying dishes, which is abnormal in comparison with a normal condition, so as to deenergize the PTC heater. CONSTITUTION:With the use of hot air produced by a PTC heater 14 incorporating a positive characteristic thermosensitive resistor, dishes 2 located in a washing tank 1 are dried, and steam is expelled from the washing tank 9 by means of a blower fan 9. A thermistor 8 detects a temperature of the inside of the tank 1, and control means 16 controls a series of program sequences for the steps of washing, rinsing and drying the dishes 2. The control means 16 determines an abnormal condition of the PTC heater 1 if the thermistor 8 detects a predetermined temperature before a predetermined time which has been previously set, elapses after the initiation of the drying step, so as to deenergize the PTC heater 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dishwasher for washing dishes by spraying washing water on the dishes stored in a washing tank.

[0002]

2. Description of the Related Art In recent years, in a drying process, a dishwasher has been proposed which uses a PTC heater having a positive temperature coefficient resistor to generate warm air and blows it directly onto tableware to dry the tableware. Has been done.

Conventionally, this type of dishwasher has been constructed as shown in FIG. The configuration will be described below.

As shown in the figure, a cleaning tank 1 stores dishes 2 inside and stores cleaning water at the bottom. Cleaning nozzle 3
Is rotatably supported in the washing tank 1 and spouts washing water toward the tableware 2. The washing pump 4 sends the washing water to the washing nozzle 3, and the washing pump 4 uses a motor 5
Driven by. The water level sensor 6 detects the water level in the cleaning tank 1 and outputs it as an electric signal. Wash water heating means 7
Is disposed at the bottom of the cleaning tank 1 to heat the cleaning water. The thermistor (temperature detection means) 8 is attached to the bottom of the cleaning tank 1 so as to be in close contact with the outside, and detects the temperature of the cleaning water.

The blower fan 9 blows out the steam in the cleaning tank 1 and is discharged from the exhaust port 10 to the outside of the machine. The tableware basket 11 is for arranging the tableware 2 and is arranged in the cleaning tank 1. The water supply means 12 supplies tap water into the cleaning tank 1, and the drainage means 13 discharges the cleaning water in the cleaning tank 1 to the outside of the tank. The PTC heater 14 is formed by a positive temperature-sensitive resistance element and generates warm air to dry the tableware 2. The control means 15 controls the sequential operation of a series of program sequences for cleaning, rinsing and drying the dishes 2.

To explain the operation of the above configuration, when the user places the tableware 2 in the tableware basket 11 and stores it in the cleaning tank 1 and puts detergent into it and starts the operation, first, the cleaning tank 1
A predetermined amount of tap water is supplied by the water supply means 12 until the water level sensor 6 detects a predetermined water level at the bottom of the. And
The motor 5 and the washing water heating means 7 are energized, and the washing water is jetted from the washing nozzle 3 toward the dishes 2 by the washing pump 4 while being heated. At this time, the temperature of the wash water is detected by the thermistor 8, and the control means 16 always grasps the temperature of the wash water.

The temperature of the wash water reaches a predetermined temperature, and
When a predetermined time has elapsed from the start of cleaning, the control means 15 ends the cleaning process, and the drain means 13 drains the cleaning water. Next, tap water is newly supplied, and the same operation as the above-mentioned washing process is performed for several minutes to drain the water. After repeating this rinsing step several times, the same operation as the washing step called a heat rinsing step is performed, and when the predetermined temperature is reached, the operation is finished and drained. Lastly, the PTC heater 14 is energized and at the same time the blower fan 9 is operated to send warm air into the cleaning tank 1 to discharge the steam in the cleaning tank 1 to the outside of the machine,
The water droplets adhering to are dried.

In the successive series of operations, the process of the operation of the PTC heater 14 in the drying process will be described with reference to the flowchart of FIG. 10. When the drying process is started,
In step 21 of the figure, timer measurement is started, and in step 22, the PTC heater 14 is energized and at the same time the blower fan 9 is operated. Due to its characteristics, the PTC heater 14 generates heat to recover the amount of heat lost by the blower fan 9.

In other words, when the power supply voltage used by the PTC heater 14 and the resistance value of the PTC heater 14 itself are constant, heat is generated almost in proportion to the amount of air blown by the blower fan 9, so that warm air can be easily controlled. In step 23, the timer measurement time t is known, and in step 24, the drying process is performed until the preset time (60 minutes in this case) has elapsed.

As a measure against abnormal heating of the PTC heater 14 compared to the standard state, although not shown, a thermostat for preventing an excessive temperature rise is additionally provided in the cleaning tank 1, and the thermostat is set to a preset abnormal temperature. (For example, 10
When 0 ° C.) is detected, the power to the PTC heater 14 is forcibly cut off in a circuit manner.

[0011]

However, in such a conventional dishwasher, when the PTC heater 14 is abnormally heated compared to the standard state, it takes time for the thermostat for preventing overheating to operate. Therefore, there is a problem that the tableware 2 made of plastic, particularly in the cleaning tank 1, is discolored or deformed due to high temperature.

The present invention is intended to solve the above-mentioned problems.
When the C heater is abnormally heated compared to the standard state, the first purpose is to detect this promptly and not energize the PTC heater.

Further, when it is detected that the PTC heater is abnormally heated as compared with the standard state, the second object is to cool the dishes in the washing tank without leaving them at a high temperature.

Further, due to factors such as continuous use of equipment,
A third object is to stably detect an abnormal heating state of the PTC heater even when the temperature in the cleaning tank at the start of the drying process is extremely high.

A fourth object is to detect an abnormal heating state of the PTC heater with a uniform reference according to the temperature of the atmosphere.

[0016] In addition, P has a uniform standard according to the voltage value of the commercial power source used under various usage conditions of the equipment.
A fifth object is to detect an abnormal heating state of the TC heater.

[0017]

In order to achieve the first object, the present invention provides a cleaning tank for storing dishes and a positive temperature coefficient resistor for generating warm air and drying the dishes. The PTC heater (heater) used, a blower fan for sending the steam in the cleaning tank to the outside of the tank, a thermistor (temperature detecting means) for detecting the temperature in the cleaning tank, and cleaning, rinsing, and drying of the tableware. A control means for controlling a series of program sequences of the stroke, wherein the control means detects the first predetermined temperature by the thermistor after the start of the drying step and before the lapse of a preset first predetermined time. , Detecting an abnormality in the heating state of the PTC heater,
The first means for solving the problem is to cut off the power supply to the heater.

Further, in order to achieve the second object, the control means of the first problem solving means, when detecting the abnormality of the heating state of the PTC heater, shuts off the energization to the PTC heater, The second problem solving means is to operate the blower fan until a predetermined time of 2 has elapsed or the thermistor detects the second predetermined temperature.

Further, in order to achieve the third object, the control means of the first means for solving the above problems is
When the temperature in the cleaning tank detected by the thermistor exceeds a predetermined range set in advance, the PTC heater is de-energized until the third predetermined time elapses, or the thermistor detects the third predetermined temperature. Up to now, operating the blower fan is the third means for solving the problem.

Further, in order to achieve the fourth object, in addition to the first problem solving means, an atmosphere temperature detecting means for detecting the ambient temperature is provided, and the control means has the atmosphere after the start of the drying process. When the first predetermined temperature is detected by the thermistor before the fourth predetermined time obtained based on the temperature detected by the temperature detection means, the abnormality in the heating state of the PTC heater is detected and the PTC heater is energized. The fourth problem solving means is to cut off the above.

Further, in order to achieve the fifth object, in addition to the above-mentioned first problem solving means, a power supply voltage detection means for detecting the voltage of the commercial power supply is provided, and the control means, after the start of the drying process, When the first predetermined temperature is detected by the thermistor before the fifth predetermined time obtained based on the voltage detected by the power supply voltage detection means, an abnormality in the heating state of the PTC heater is detected and the PTC heater is detected. The fifth problem solving means is to cut off the energization.

[0022]

According to the first means for solving the above problems, the present invention provides:
When the first predetermined temperature is detected by the thermistor before the first predetermined time set in advance during the drying process has elapsed,
That is, when the amount of heat generated by the PTC heater per unit time exceeds the planned value, it is possible to detect an abnormal heating state of the PTC heater and not energize the PTC heater.

Further, according to the second problem solving means, the PTC
When detecting an abnormal heating state of the heater, leave the dishes at a high temperature to operate the blower fan until the second predetermined time elapses or the thermistor detects the second predetermined temperature. Can be cooled without.

According to the third means for solving the problems, when the temperature in the cleaning tank at the start of the drying process exceeds the predetermined range by the thermistor, the third predetermined time elapses or the thermistor keeps the third predetermined temperature. The blower fan is operated and the drying process is performed again until it is detected.Therefore, even if the temperature in the cleaning tank at the beginning of the drying process is extremely high due to factors such as continuous use of the equipment, stable operation is possible. Thus, the abnormal heating state of the PTC heater can be detected.

Further, the fourth problem solving means obtains the fourth predetermined time based on the temperature of the atmosphere surrounding the equipment by the atmosphere temperature detecting means, and the thermistor is used before the fourth predetermined time elapses during the drying process. When the first predetermined temperature is detected, the abnormal heating state of the PTC heater is detected. That is, the abnormal heating state of the PTC heater can be detected with a uniform reference according to the temperature of the atmosphere surrounding the device.

According to the fifth problem solving means, the power supply voltage detection means obtains the fifth predetermined time based on the voltage value of the commercial power supply, and the thermistor is used before the fifth predetermined time elapses during the drying process. When the first predetermined temperature is detected, the abnormal heating state of the PTC heater is detected. That is, the abnormal heating state of the PTC heater can be detected with a uniform reference according to the voltage value of the commercial power supply used under various usage conditions of the device.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIG. The same components as those of the above-mentioned conventional example are designated by the same reference numerals and the description thereof will be omitted.

As shown in the figure, the control means 16 controls a series of program sequences for cleaning, rinsing, and drying the dishes 2 and, at the same time, after the start of the drying process, a preset first predetermined time (for example, When the first predetermined temperature (for example, 70 ° C.) is detected by the thermistor (temperature detecting means) 8 before 10 minutes have passed, an abnormality in the heating state of the PTC heater (heater) 14 is detected, and the PTC heater 14 is detected. It is designed to cut off the power supply to.

The operation of the above configuration will be described with reference to FIG. The series of sequential operations of the cleaning, rinsing, and drying process of the tableware 2 by the control means 16 are the same as in the conventional example, and therefore the description thereof is omitted, and the process of detecting an abnormal heating state of the PTC heater 14 will be described. .

When the drying process is started, measurement of the timer is started in step 21, and in step 22, the blower fan 9 is operated at the same time as energizing the PTC heater 14. In step 23, the timer measurement time t is known, in step 25, the temperature T in the cleaning tank 1 is known by the thermistor 8, and in step 26, the temperature T is the first predetermined temperature (70
C.) is not reached, the drying process is performed until the time set in step 24 (60 minutes in this case) elapses, and the process ends.

On the other hand, when it is found in step 26 that the temperature T has reached the predetermined temperature (70 ° C.), whether the first predetermined time (10 minutes) has elapsed since the start of the drying process in step 27. If the first predetermined time has not elapsed yet, it is determined that the PTC heater 14 is in an abnormal heating state when the heat generation amount of the PTC heater 14 per unit time exceeds the planned value. In step 28, the PTC heater 14 and the blower fan 9 are stopped, and in step 29, an abnormality is notified to alert the user.

As a result, when the PTC heater 14 is abnormally heated compared to the standard state, this is promptly detected,
It is possible not to energize the PTC heater 14.

In the above embodiment, the specific values and timings of the temperature of the thermistor 8 and the abnormality detection temperature of the PTC heater 14 are shown.
It does not limit the means for detecting the abnormal heating state.

Next, a second embodiment of the present invention will be described. The control means 16 in FIG.
When the abnormality of the heating state of No. 4 is detected, the PTC heater 14
The blower fan 9 is operated until the current is cut off and the thermistor 8 detects the second predetermined temperature (for example, 40 ° C.). The other structure is the same as that of the first embodiment.

The operation of the above configuration will be described with reference to FIG. It should be noted that steps 21 to 29 in FIG. 3 are the same as those in the first embodiment described above, and a description thereof will be omitted.

In the drying process, it is determined in steps 26 to 29 that the PTC heater 14 is in an abnormal heating state, the power supply to the PTC heater 14 is cut off, and an abnormality is informed. 9 is operated to discharge the high temperature steam in the cleaning tank 1 to the outside of the tank. In step 31, the temperature T in the cleaning tank 1 is known by the thermistor 8, and in step 32, the blower fan 9 is operated until the value of the temperature T detects the second predetermined temperature (40 ° C.).

As a result, when it is detected that the PTC heater 14 is abnormally heated as compared with the standard state, the tableware 2
Can be prevented from being left at a high temperature.

In the above embodiment, the PTC heater 14
The blower fan 9 is operated until the thermistor 8 detects the second predetermined temperature (40 ° C.) after the power supply to the cleaning tank 1 is cut off, but the temperature in the cleaning tank 1 drops to about 40 ° C. The blower fan 9 may be operated until the second predetermined time period (for example, 20 minutes) has elapsed.

Next, a third embodiment of the present invention will be described. When the temperature in the cleaning tank 1 detected by the thermistor 8 exceeds a preset predetermined range at the start of the drying process, the control means 16 in FIG. 1 shuts off the energization to the PTC heater 14, and the thermistor 8 causes the third operation. The blower fan 9 is operated until a predetermined temperature (for example, 25 ° C.) is detected. The other structure is the same as that of the first embodiment.

The operation of the above configuration will be described with reference to FIG. It should be noted that steps 21 to 29 in FIG. 4 are the same as those in the first embodiment described above, and a description thereof will be omitted.

At the start of the drying process, step 33
At step 34, the temperature T in the cleaning tank 1 is known by the thermistor 8, and at step 34, the value of the temperature T is set to a predetermined temperature (4
If the temperature exceeds 0 ° C., the blower fan 9 is operated in step 35 without starting the drying process immediately, that is, without energizing the PTC heater 14, and the high temperature steam (in the cleaning tank 1) ( (Or air) is discharged to the outside of the bath, and in step 36, the temperature T in the washing bath 1 is set by the thermistor 8.
Then, in step 37, the blower fan 9 is operated until the value of the temperature T detects the third predetermined temperature (25 ° C.), and then the drying process is started again, and the process proceeds to step 21 and the following steps. Similar to the first embodiment, an abnormal heating state of the PTC heater 14 can be detected.

As a result, due to factors such as continuous use of the equipment, the abnormal heating state of the PTC heater 14 can be stably detected even when the temperature in the cleaning tank 1 at the start of the drying process is extremely high. it can.

In the above embodiment, the blower fan 9 is operated until the thermistor 8 detects the third predetermined temperature (25 ° C.) at the start of the drying process. The blower fan 9 may be operated until the third predetermined time (for example, 40 minutes) required for the internal temperature to drop to about 25 ° C. elapses.

Next, a fourth embodiment of the present invention will be described with reference to FIG. The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

As shown in the figure, the ambient temperature detecting means 17
Detects the ambient temperature and inputs the output to the control means 18. When the control means 18 detects the first predetermined temperature (70 ° C.) by the thermistor 8 after the start of the drying process and before the fourth predetermined time obtained based on the temperature detected by the ambient temperature detection means 17 has elapsed, PTC
An abnormality in the heating state of the heater 14 is detected, and the PTC heater 1
The power to 4 is cut off.

The operation of the above configuration will be described with reference to FIG. It should be noted that steps 21 to 29 in FIG. 6 are the same as those in the first embodiment described above, and a description thereof will be omitted.

When the drying process is started, timer measurement is started in step 21, and the blower fan 9 is operated at the same time as energizing the PTC heater 14 in step 22. In step 23, the time t measured by the timer is known, in step 25, the temperature T in the cleaning tank 1 is known by the thermistor 8, and in step 38, the ambient temperature To around the equipment is known by the ambient temperature detecting means 15. When it is known that the temperature T has reached the first predetermined time (70 ° C.) at 26, a fourth predetermined time corresponding to the ambient temperature To is set at step 39, step 39-1 and step 39-2. .

In this embodiment, when the ambient temperature To is 40 ° C. or higher, the fourth predetermined time is 6 minutes, and the ambient temperature T
When o is 30 ° C. or higher and lower than 40 ° C., the fourth predetermined time is 8 minutes, and when ambient temperature To is 20 ° C. or higher and lower than 30 ° C., the fourth predetermined time is 10 minutes and atmospheric temperature To is When the temperature is lower than 20 ° C., the fourth predetermined time is 12 minutes. Step 27-1, Step 27-2, Step 2
It is determined in 7-3 and step 27-4 whether the fourth predetermined time has elapsed. If the fourth predetermined time has not elapsed yet, it is determined that the PTC heater 14 is in an abnormal heating state. In step 28, the PTC heater 14 and the blower fan 9 are stopped, and in step 29, an abnormality is notified to alert the user.

As a result, the abnormal heating state of the PTC heater 14 can be detected with a uniform reference according to the temperature of the atmosphere surrounding the equipment.

In the above embodiment, in the process of obtaining the fourth predetermined time period according to the ambient temperature, several threshold values are provided and the detected ambient temperatures are classified into ranks. I got a certain time of, but this is especially P
The means for detecting the abnormal heating state of the TC heater 14 is not limited, and for example, the fourth predetermined time may be calculated from a calculation formula using the value of the ambient temperature.

Next, a fifth embodiment of the present invention will be described with reference to FIG. The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

As shown in the figure, the power supply voltage detecting means 19
Detects the voltage of the commercial power supply and inputs the output to the control means 20. When the control means 20 detects the first predetermined temperature (70 ° C.) by the thermistor 8 after the start of the drying process and before the fifth predetermined time determined based on the voltage detected by the power supply voltage detection means 19 has elapsed, PTC
The abnormality of the heating state of the heater 14 is detected, and the power supply to the PTC heater 14 is cut off.

The operation of the above configuration will be described with reference to FIG. It should be noted that steps 21 to 29 in FIG. 8 are the same as those in the above-described first embodiment, and a description thereof will be omitted.

When the drying process is started, timer measurement is started in step 21, and the blower fan 9 is operated at the same time as energizing the PTC heater 14 in step 22. In step 23, the time t measured by the timer is known, in step 25, the temperature T in the cleaning tank 1 is known by the thermistor 8, and in step 40, the voltage value Vo of the commercial power source to be used is known by the power source voltage detecting means 19, When it is known that the temperature T has reached the first predetermined temperature (70 ° C.) in step 26, the fifth predetermined time corresponding to the voltage value Vo is set in step 41, step 41-1 and step 41-2. To do.

In this embodiment, when the voltage value Vo is 120 V or more, the fifth predetermined time is 6 minutes and the voltage value Vo is 1
If 00V or more and less than 120V, set the fifth predetermined time to 8
If the voltage value Vo is 90 V or more and less than 100 V, the fifth predetermined time is 10 minutes and the voltage value Vo is 90 V.
If less, the fifth predetermined time is set to 12 minutes. Step 27-1 and Step 27-2 and Step 2
In 7-3 and step 27-4, it is determined whether the fifth predetermined time has elapsed. If the fifth predetermined time has not elapsed, it is determined that the PTC heater 14 is in an abnormal heating state. Then, in step 28, the PTC heater 14 and the blower fan 9 are stopped, and in step 29, an abnormality is notified to call attention to the user.

As a result, it is possible to detect an abnormal heating state of the PTC heater 14 with a uniform reference according to the voltage of the commercial power source used under various usage conditions of the equipment.

In the above embodiment, in the process of obtaining the fifth predetermined time period according to the power supply voltage value, several threshold values are provided and the detected power supply voltage value is classified into ranks, and the detected power supply voltage values are classified into ranks. I got a fifth predetermined time, which is especially P
The means for detecting the abnormal heating state of the TC heater 14 is not limited, and for example, the fifth predetermined time may be calculated from a calculation formula using the power supply voltage value.

[0058]

As is apparent from the above embodiments, according to the present invention, a PTC using a washing tank for storing dishes and a positive temperature coefficient resistor for generating warm air and drying the dishes is used. A heater, a blower fan for sending the steam in the cleaning tank to the outside of the tank, a thermistor for detecting the temperature in the cleaning tank, and a control means for controlling a series of program sequences for cleaning, rinsing and drying the dishes. The control means detects an abnormality in the heating state of the PTC heater when the first predetermined temperature is detected by the thermistor after the start of the drying process and before the elapse of a first predetermined time set in advance. However, since the power supply to the PTC heater is cut off, when the first predetermined temperature is detected by the thermistor before the first predetermined time set in advance during the drying process, that is, in the unit time If the heating value of the PTC heater or exceeds the planned value, it detects an abnormal heating state of the PTC heater can be so as not to perform power supply to the PTC heater.

Further, when the control means detects an abnormality in the heating state of the PTC heater, the control means cuts off the energization to the PTC heater until the second predetermined time elapses or the thermistor keeps the second predetermined temperature. Since the blower fan is operated until it is detected, when the abnormal heating state of the PTC heater is detected, the blower fan is blown until the second predetermined time elapses or the thermistor detects the second predetermined temperature. Since the fan is operated, the tableware can be cooled without being left at a high temperature, and thus, the discoloration or deformation of the tableware can be prevented.

When the temperature in the cleaning tank detected by the thermistor exceeds the preset predetermined range at the start of the drying process, the control means shuts off the power supply to the PTC heater and the third predetermined time elapses. The blower fan is operated until the temperature is detected by the thermistor or until the thermistor detects the third predetermined temperature. Therefore, if the temperature in the cleaning tank at the start of the drying process exceeds the predetermined range by the thermistor, the third predetermined time is reached. Until the time elapses, or the thermistor detects the third predetermined temperature, the blower fan is operated and the drying process is performed again. Even when the temperature in the cleaning tank is extremely high, it is possible to stably detect the abnormal heating state of the PTC heater.

Also, an atmosphere temperature detecting means for detecting the ambient temperature is provided, and the control means obtains the fourth temperature obtained based on the temperature detected by the atmosphere temperature detecting means after the start of the drying process.
When the first predetermined temperature is detected by the thermistor before the predetermined time of, the abnormal temperature of the PTC heater is detected and the energization to the PTC heater is cut off. A fourth predetermined time is obtained based on the temperature of the atmosphere surrounding the equipment, and the first thermistor is used to measure the first predetermined time before the fourth predetermined time elapses during the drying process.
When the predetermined temperature is detected, the abnormal heating state of the PTC heater is detected. That is, the abnormal heating state of the PTC heater can be detected with a uniform reference according to the temperature of the atmosphere surrounding the device.

Further, the power supply voltage detection means for detecting the voltage of the commercial power supply is provided, and the control means obtains the fifth voltage based on the voltage detected by the power supply voltage detection means after the start of the drying process.
When the first predetermined temperature is detected by the thermistor before the predetermined time has passed, the abnormality in the heating state of the PTC heater is detected and the power supply to the PTC heater is cut off. If the fifth predetermined time is calculated based on the voltage value of the commercial power source used by the dishwasher and the first predetermined temperature is detected by the thermistor before the fifth predetermined time elapses during the drying process, the PTC heater malfunctions. Detects various heating conditions. That is, the abnormal heating state of the PTC heater can be detected with a uniform reference according to the voltage value of the commercial power supply used under various usage conditions of the device.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of a dishwasher according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing an operation of a PTC heater of the dishwasher and a process of detecting an abnormal heating state.

FIG. 3 is a flowchart showing the operation of the PTC heater of the dishwasher of the second embodiment of the present invention and the process of detecting an abnormal heating state.

FIG. 4 is a flowchart showing the operation of the PTC heater of the dishwasher of the third embodiment of the present invention and the process of detecting an abnormal heating state.

FIG. 5 is a system configuration diagram of a dishwasher according to a fourth embodiment of the present invention.

FIG. 6 is a flowchart showing the operation of the PTC heater of the dishwasher and the process of detecting an abnormal heating state.

FIG. 7 is a system configuration diagram of a dishwasher according to a fifth embodiment of the present invention.

FIG. 8 is a flowchart showing an operation of the PTC heater of the dishwasher and a process of detecting an abnormal heating state.

[Fig. 9] System configuration diagram of a conventional dishwasher

FIG. 10 is a flowchart showing an operation of the PTC heater of the dishwasher and a process of detecting an abnormal heating state.

[Explanation of symbols]

 1 Washing Tank 2 Tableware 8 Thermistor (Temperature Detection Means) 9 Blower Fan 14 PTC Heater (Heater) 16 Control Means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Taniguchi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Masaki Yura, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (5)

[Claims] 1. A washing tank for storing dishes, a heater using a positive temperature-sensing resistor element for generating warm air to dry the dishes, and a blower fan for sending steam in the washing tank to the outside of the vessel. And a temperature detecting means for detecting the temperature in the cleaning tank, and a control means for controlling a series of program sequences for cleaning, rinsing and drying the dishes, the control means, after the start of the drying step, When the first predetermined temperature is detected by the temperature detecting means before the preset first predetermined time has elapsed, an abnormality in the heating state of the heater is detected and the power supply to the heater is cut off. dishwasher. 2. The control means, when detecting an abnormality in the heating state of the heater, shuts off the energization to the heater until the second predetermined time elapses or the temperature detecting means keeps the second predetermined temperature. The dishwasher according to claim 1, wherein the blower fan is operated until it is detected. 3. The control means, when the temperature in the cleaning tank detected by the temperature detection means exceeds a preset predetermined range at the start of the drying process, shuts off the power supply to the heater, and the third predetermined time elapses. The dishwasher according to claim 1, wherein the blower fan is operated until the temperature is detected, or until the temperature detecting means detects the third predetermined temperature. 4. An atmosphere temperature detecting means for detecting an ambient temperature is provided, and the control means, after the start of the drying process, before a fourth predetermined time obtained based on the temperature detected by the atmosphere temperature detecting means elapses. When the first predetermined temperature is detected by the temperature detecting means, an abnormality in the heating state of the heater is detected,
The dishwasher according to claim 1, wherein the heater is de-energized. 5. A power supply voltage detection means for detecting the voltage of the commercial power supply is provided, and the control means, after the start of the drying process, before a fifth predetermined time period obtained based on the voltage detected by the power supply voltage detection means has elapsed. When the first predetermined temperature is detected by the temperature detecting means, the abnormality of the heating state of the heater is detected,
The dishwasher according to claim 1, wherein the heater is de-energized.