JPH01119222A - Dish washer - Google Patents

Abstract

PURPOSE: To prevent a heater itself and surroundings of the heater from being damaged by overheating caused by no-water heating by stopping heating of washing water by a heater when electric current supplied to a motor for driving a pump is changed to overloading or light loading. CONSTITUTION: Water is fed to a point where water level is detected by means of a float type washing water level switch 10 and the washing water is heated and circulated by a washing pump driven by a motor 18 and is sprayed to wash tablewares. In this case, electric current supplied to the motor 18 is detected by an electric current detecting means 25 and the detected electric current value is compared with a reference electric current value under a condition where there exists no washing water or the water level becomes low for the motor 18 by a comparative means C. In addition, a time detecting part 34 detects whether comparative output continues for a specified time and an disorder control part 35 stops heating by a heater 6 based on a time detecting signal and actuates an abnormally low water level informing means 24. As the result, it is possible to prevent the heater itself and surroundings of the heater from being damaged by overheating caused by no-water heating.

Description

DETAILED DESCRIPTION OF THE INVENTION B) Industrial Application Field The present invention supplies water until it is detected by a float-type washing water level switch, heats this washing water, and circulates and sprays it with a motor-driven washing pump. Related to dishwashers that wash tableware.

(b) Conventional technology This type of dishwasher supplies water before driving the pump.
When the water surface is relatively quiet, the washing water level is detected by a water level switch of type O-), and then the washing water is heated by a heater, circulated and sprayed, and the tableware is washed using the temperature and spraying force. If water leaks for some reason during this cleaning, the heater will be in an empty state, not only overheating the surrounding area but also deteriorating the heater itself. Therefore, if an attempt is made to prevent dry boiling by stopping the output when the water level switch is set to 0FFI, the water surface during cleaning will be turbulent and will easily respond to a momentary drop in the water level.

On the other hand, structures that prevent dry heating have been proposed for a relatively long time in the field of baths and water heaters, and an example is
It is disclosed in Japanese Patent No. 3457.

In this case, a pump is installed between the bath and the heat exchanger to be heated, and while the pump is circulating water, the water supply pressure turns on the switch 1ONj, and this switch turns ONI.

Allows heating when Then, when there is no water or the water level is low and water supply pressure cannot be maintained, the switch can be turned off and heating can be stopped. While even a small amount of water is being circulated, the water supply pressure does not drop all the time, and the water supply pressure tends to fluctuate, making the detection state unstable.

The present invention focuses on the fact that the current supplied to the pump drive motor is a relatively stable value at the rated load (washing water level), but it clearly changes at 9 o'clock when the load changes from this point to overload. The purpose of this invention is to perform extremely stable dry-boiling detection and ensure safety. A current detection means for detecting, a comparison means for comparing the detected current value with a reference current value in a state where there is no cleaning water or at a low water level for the motor, and a time for detecting that the comparison output continues for a predetermined time. The present invention includes a detection section and an abnormality control section that stops heating the cleaning water by the heater and operates an abnormally low water level notification means based on a time detection signal.

(to) Examples To explain based on the drawings below, in Fig. 2 (1)
The body of the tabletop dishwasher is equipped with a door (2) that opens downward at the front opening, and a washing tank (3) inside. In the middle of this washing tank (3) there is a tableware (4) which can be taken in and out through the front opening.

At the bottom of the washing tank (3), there is an arm nozzle (5) that rotates and sprays washing water onto the tableware cup (4), and a sheathed heater (6) used in the washing, rinsing, and drying processes. A recess (8) in which a removable filter (7) is provided is formed at the bottom. (9) is the cleaning tank (3
), and the cleaning water level switch (101) detects the cleaning water level by the vertical movement of the float.In addition, there is a water level detection means in the cleaning tank (3) at the outer bottom near the front that detects the water temperature in the tank. A thermistor fiυ is provided to (8) A cleaning pump that supplies cleaning water to the arm nozzle (5), injects it, and circulates it, α
η is a blower that circulates drying air within the tank. The cleaning pump (161) is driven by an AC motor α second such as a WS motor.

A control box (1!J) having an operation surface is provided at the lower front of the main body (1), and the operation surface is provided with a start key (2) that also serves as a pause key and a power switch 12υ.

The control pocket xris above contains ROM, RAM, and OpU.
A control circuit centered on a microcomputer (hereinafter referred to as microcomputer) consisting of , Ilo, etc. is incorporated, and its circuit diagram is shown in FIG. That is, the microcomputer inputs signals from the cleaning water level switch α1) thermistor (Ill,
3. Outputs an operating signal to the drain pump [51, cleaning pump (Le (motor 1 second)), and blower (171).The microcomputer also outputs an AO solenoid [51] that forcibly opens the power switch that is closed. ] and buzzer c!4.Furthermore, the microcontroller has a current transformer □□□ which serves as a current detection means for detecting the current supplied to the motor for a second, and outputs the current value equivalent to the detected current value. Voltage value (1)
The overload reference voltage value output by the k microcontroller is compared with the overload detection comparator (to), and the voltage value (I) corresponding to the detected current value is compared with the light (no) load reference voltage value. A light (no) load comparator (5) is used to compare the comparison means, and the comparison means (C) outputs the comparison output, that is, the overload detection signal or the (no) load detection signal. I am trying to input it.

Next, the control operation 1 by the microcomputer will be explained based on the flowchart in FIG. 6. First, the power switch (21
) is turned on, the initial setting is to clear it in the RAM (281), and call up and set the course and time from the ROMfi.

Regardless of the operation of the start key ■, the thermistor riυ
The detected temperature is checked, and if the abnormal temperature control section (7) consisting of a microcomputer detects a temperature of 80° C. or higher, it will stop all output and notify the temperature that there is an abnormality. In addition, a frequency discrimination section C31) consisting of a microcomputer
determines the frequency of the power supply, and if it is 50H2, a frequency 7 lag is set, and if it is 60Hz, it is turned off.

When the course and time are set and the start key (2) is operated, each process of washing, rinsing, and drying is executed by each process control section 04 constituted by a microcomputer. In each process of washing and rinsing, the water supply valve (13) is opened to supply water, and when the washing water level switch αQ is tripped, the water supply valve α旙 is closed and the washing pump ae is operated by the motor tt.
S, and the heater (6) is heated until the water temperature rises to a predetermined temperature, for example, 60°C.

Washing or rinsing is executed by operating the washing pump (161 and heater (6)), but if the washing pump ae is operated while the motor Q8 is locked due to freezing etc., an overload condition occurs. It is possible to check whether there is a leakage of cleaning water and whether there is no load or load condition.Then, since the supply current of the motor group varies depending on the power supply frequency,
The frequency flag is checked, and the load status is checked by distinguishing it into 50Hg and 6 (HF2).0 First, the microcomputer compares the reference values corresponding to overload and @(no) load with each comparator @IJT of the comparison means (C). ) and is compared with a detected value (r) corresponding to the motor current detected by the current transformer (c). Overload detection signal or light (no) as comparison output
When the load detection signal is input to the microcomputer, the microcomputer's 5-second counter (support) starts counting, and when it counts up, the time detection section 0 of the microcomputer detects the time detection signal? Input to the abnormality control section (to) consisting of a microcomputer.

In this way, the abnormality control unit C (51) stops the heater (6) and the motor αl, and also causes the display and buzzer (24) to issue a notification corresponding to overload or light (no) load. In the case of freezing, @ (no load), it is displayed as the cleaning water system. The load current is as shown below.

Therefore, the standard values for equivalent to overload and light (no) load are shown numerically in Figure 4 in consideration of safety.
% 60H2. The 95-second counter is the current equivalent value (I
) is cleared each time the current equivalent value returns to the normal range in order to cope with the temporal increase or decrease of . To improve sex, the time can be changed.

In this way, when the cleaning pump (161) is operating without any abnormality and the water temperature reaches the predetermined temperature (60°C), the reaching flag is set and the heater (6) is turned off. When 12 minutes of washing is executed without any abnormalities, a 12 minute flag is set and a 1 minute counter t, 1) is set.
9 starts counting, and when the count is up, the motor Q8 is also turned off, and the drain pump (151) executes the draining operation, and this process ends.

After that, rinse and dry (heater (6) was set to 0N-O from the beginning)
) is executed, and when the course is finished, the buzzer c
! 4 gives notification of termination, which is different from abnormality.

(g) Effects of the Invention According to the present invention, it is possible to detect leakage from the cleaning bottle with extremely high accuracy and stability, which is difficult to detect with a float type water level switch or pressure switch, and to detect leakage from the heater itself due to dry heating. It is possible to prevent overheating damage around the heater and provide a highly safe dishwasher.

[Brief explanation of the drawing]

Fig. 1 is a control circuit diagram of a dishwasher according to the present invention, Fig. 2 is an internal mechanism diagram, Fig. 3 is a flowchart for explaining the overall main operations, and Fig. 4 is an explanation of the operation of the washing process. This is a flowchart for 0 αQ...Washing water level switch, (161-...Washing pump, Ql-...Motor, Q3...Microcomputer, cps...
・Current transformer, (c) c2n... comparator, (C
)... Comparison means, c33... 5 seconds counter, 134
1... Time detection section, (to)... Abnormality control section.

Claims (1)

[Claims] (1) In a device that washes dishes by supplying water until it is detected by a float-type washing water level switch, heating this washing water, and circulating and spraying it with a motor-driven washing pump, the motor A current detection means for detecting the current supplied to the motor, and a current detection means for detecting the current supplied to the motor.
a comparison means for comparing with a reference current value in a state where the water level is low; a time detection section for detecting when the comparison output continues for a predetermined time; and a time detection section for stopping heating by the heater based on the time detection signal, A dishwasher comprising: an abnormality control section that activates a low water level notification means.