JPH06105790A - Dish washing and drying machine - Google Patents

Abstract

PURPOSE:To quicken the rise of temperature and prevent generation of overshoot by feeding current to a heating means with a duty ratio having long On period until the specified temp. is attained, and changing over into a duty ratio having a short On period after attainment of the specified temp. CONSTITUTION:When the drying stage is entered, the temp Th2 in a wash tub 10 sensed by a temp. sensing element 2 is compared with the specified temp. value T1 (65 deg.C), and if below T1, current is fed to a heater 16 at intervals having a long On time t1. When the temp. Th2 exceeds T1, the sensing temp. Th2 is compared with the set temp. having a short On time t2, and reaching the set temp. value T2 shuts off current feed to the heater 16. That is, current feed is made with a duty ratio having a long On period until T1 is reached, and the heater 16 is fed with current with a duty ratio having a short On time when T1 is reached.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dishwasher / dryer, and more particularly to temperature control in the drying process.

[0002]

2. Description of the Related Art Washing and drying with a dishwasher / dryer includes a washing and rinsing step of removing the stains on the dishes which are heated by a heater and are sprayed with water from a nozzle into a washing tank. After the water in the cleaning tank is drained, it consists of a drying step of heating the inside of the cleaning tank with a heater. The temperature control in the cleaning tank during this drying step is generally detected by a temperature detection element such as a thermistor. This is done by comparing the temperature with a preset temperature. When the temperature is below the set temperature, the heater is energized at a predetermined duty ratio, and when the temperature is above the set temperature, the energization to the heater is cut off. The duty ratio control is
Generally, the heater is also used for heating the washing water, but since air has less heat conduction than water, if the heater is constantly energized for drying, the area around the heater will become too hot and the inside of the washing tank This is because there is a large variation in the temperature distribution of.

[0003]

Here, in order to shorten the time required for drying, it is preferable to lengthen the ON time of the duty ratio in energizing the heater. Since the temperature difference between the temperature detection unit where the detection element is installed becomes large, an overshoot that exceeds the set temperature occurs, and the ambient temperature is high, the power supply voltage is high, and the temperature detection element is When the cleaning tank is installed outside the cleaning tank, overshoot is particularly remarkable, and when the cleaning tank is made of synthetic resin, the cleaning tank is deformed or discolored. To avoid this, if the ON time in the duty ratio of the heater energization is shortened, the rise time until it reaches the set temperature becomes longer, and if the ambient temperature is low or the power supply voltage is low, the drying performance will be greatly reduced. Will be lost.

Further, since the temperature detecting element gets wet in the cleaning process and the rinsing process performed prior to the drying process,
If the temperature detection element is placed outside the cleaning tank because the temperature of the air inside the cleaning tank cannot be detected accurately, the temperature rise near the temperature detection element will be delayed compared to when the temperature detection element is placed inside the cleaning tank. However, since this delay becomes larger when the temperature is raised from a low temperature, an overshoot is particularly likely to occur at the first rising.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a dishwasher / dryer in which a temperature rise in a drying process rises quickly and an overshoot does not occur. It is in.

[0006]

SUMMARY OF THE INVENTION The present invention, however, comprises a heating means for heating the inside of the cleaning tank and a temperature detecting means for detecting the temperature in the cleaning tank, and the temperature detecting means performs the cleaning by the heating means. In a dish washer / dryer that controls the temperature of the heating in the tank, the duty ratio of energization to the heating means is changed at a predetermined temperature below the set temperature at which the energization to the heating means is cut off, The first feature is that the on-time is increased below and the on-time is decreased at a predetermined temperature or higher, and a plurality of set temperatures are set so as to cut off the power supply to the heating means. The second feature is that the set temperature that is compared with the detected temperature immediately after the start of energization of the heating means is set to be lower than the set temperature that is the comparison target from the next time onward.

[0007]

According to the first feature of the present invention, since the heating means is energized with a long duty ratio until the predetermined temperature is reached, a quick start-up can be obtained, and the predetermined temperature can be obtained. After reaching, the duty ratio is switched to a short on-time, so that an overshoot that exceeds the set temperature is unlikely to occur.
Further, according to the second feature, since the energization to the heating means is cut off at a lower temperature at the rising time when the overshoot is most likely to occur, the overshoot at the rising time hardly occurs.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the illustrated embodiments. As shown in FIG. 3, this dishwasher / dryer has a washing tank 10, a washing pump 11, a drainage pump 12, a fixed nozzle 13, It is equipped with spray nozzles 14 and 15, a heater 16 and the like, and dishes are set in the cleaning tank 10, and a special detergent and a dry finishing agent are set in the detergent feeding device 17 and the finishing agent feeding device 18, respectively. After that, when the door is closed, the door switch 21 is turned on and the preparation for operation is completed. In this state, the control circuit power switch 22 of the operation panel is turned on, and the start switch 23 is pressed to wash and dry in the standard mode. Is started.

That is, when the drainage pump 12 first operates to drain water until the normal water level detection pressure switch 19 is turned off, then the water supply solenoid valve 31 is turned on and the water supply into the cleaning tank 10 is started. When the normal water level detection pressure switch 19 is turned on, the water supply solenoid valve 31 is closed and the water supply process is completed. After that, the cleaning pump 11 is operated, the heater 16 is energized, and the detergent throwing device 17 throws in the detergent. The washing water pressurized by the washing pump 11 is fixed nozzle 13 and spray nozzle 14. ，
15 is sprayed from the spray nozzles 14 and 15 at this time.
Rotates by the spray pressure and applies cleaning water to every corner of the tableware. The cleaning water sprayed from the nozzles 13, 14, 15
After being filtered by the filter 32, it returns to the washing pump 11. The cleaning process in which the cleaning water is sprayed in this way is continued for a predetermined time, and during this time, the temperature of the heater 16 is controlled so as to maintain a set temperature (for example, 60 ° C.).

When the cleaning process is completed, the water is once drained and then water is supplied again, and the nozzles 13 and 1 are connected.
A rinsing step of injecting water from 4, 15 is performed, and drainage is performed after a predetermined time. This rinsing step is repeated a plurality of times, and in the final rinsing step, rinsing is performed by the hot water heated by the heater 16, the dry finishing agent is added immediately before the completion of the hot water rinsing, and then the drainage is performed.

Next, in the drying process, a control circuit consisting of a microcomputer for controlling the operation of the dishwasher / dryer is washed by a temperature detecting element 2 such as a thermistor attached to the outer wall surface of the washing tank 10. Tank 10
Based on the temperature comparison between the temperature Th2 in the cleaning tank 10 detected through the wall of the heater and preset temperatures T1, T2 and T3, the energization of the heater 16 is controlled until the temperature reaches the predetermined temperature T1. Performs energization with a duty ratio having a long on-time (here, energization of intervals in which on and off are repeated at predetermined time intervals), and a predetermined temperature T
When the value exceeds 1, the energization is performed with a duty ratio having a short ON time, and when the set temperature T2 or T3 is reached, the energization to the heater 16 is cut off.

That is, the control circuit controls the operation of the heater 16 based on the flowcharts shown in FIGS. 1 and 2 as a subroutine for the drying step. When entering, the drying timer is turned on, the initial flag is 0,
After performing the initial setting with the heater on flag set to 1,
Temperature Th2 in the cleaning tank 10 detected by the temperature detection element 2
Is compared with a predetermined temperature T1 (for example, 65 ° C.), and when the temperature is equal to or lower than the predetermined temperature T1, the initial flag is set to 1, and the on-time t1 (for example, 18 seconds) set by the on-timer and the off-timer are set. The heater 16 is energized with the interval energization for the set off time (for example, 20 seconds). If the detected temperature Th2 exceeds the predetermined temperature T1, as shown in FIG. 2, when the initial flag is 1, the detected temperature Th2 is compared with the set temperature T2 (for example, 78 ° C.), and the initial flag is 0. Sometimes the detected temperature Th
2 is compared with the set temperature T3 (for example, 80 ° C.), and if the set temperatures are T2 and T3 or less, the on-time t2 (for example, 12 seconds) set by the on-timer and the off-time set by the off-timer. When the heater 16 is energized at intervals of (for example, 20 seconds) and the detected temperature Th2 reaches the set temperatures T2 and T3, the energization of the heater 16 is cut off and the initial flag is set to zero.

Until the temperature in the cleaning tank 10 reaches the predetermined temperature T1, the heater 16 is energized with a duty ratio having a long ON time so that the temperature rises quickly and reaches the predetermined temperature T1. For example, by energizing with a duty ratio having a short on-time, overshoot is less likely to occur. Further, when heating is started from a state where the detected temperature Th2 is equal to or lower than the predetermined temperature T1, the heater 16 By setting the set temperature at which the power supply to the power supply is cut off to a temperature T2 lower than the set temperature T3 for the subsequent power supply cutoff, it is possible to more reliably prevent overshoot at the start of heating at which overshoot is most likely to occur. There is something.

It should be noted that when the interval energized state is switched to the cutoff state, the off state is maintained for a required off holding time before allowing the transition to the interval energized state. When the cutoff state is changed to the interval energized state, The chattering operation is prevented by keeping the ON state for the required ON holding time. The temperature detecting element 2 attached to the outer wall surface of the cleaning tank 10 is used in the drying step because when the temperature detecting element is arranged in the cleaning tank 10, it is used in the cleaning step and the rinsing step performed before the drying step. This is because the temperature inside the cleaning tank 10 cannot be accurately detected if the temperature detecting element is wet with the water. The water temperature detection for controlling the temperature of the water in the cleaning process and the rinsing process is performed by the temperature detection element 3 arranged in the cleaning tank 10.

[0015]

As described above, according to the first feature of the present invention, since the heating means is energized with a duty ratio having a long on-time until a predetermined temperature is reached, a quick rise can be obtained. In addition, in order to switch to a duty ratio with a short on-time after reaching the predetermined temperature,
Overshoot that exceeds the set temperature is unlikely to occur, and even if the cleaning tank is made of synthetic resin or the temperature detection element is installed outside the cleaning tank, discoloration deformation of the cleaning tank due to overshoot does not occur. It is a thing.

Further, according to the second feature, since the energization to the heating means is cut off at a low temperature at the rising time when the overshoot is most likely to occur, the overshoot at the rising time hardly occurs and is stable. You can get the action.

[Brief description of drawings]

FIG. 1 is a flowchart showing an operation in one embodiment.

FIG. 2 is a flowchart showing an operation of the above.

FIG. 3 is a schematic sectional view.

[Explanation of symbols]

 2 temperature detection element 10 cleaning tank 16 heater T1 predetermined temperature T2, T3 set temperature Th2 detection temperature

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsunori Teramoto 1-52-1 Oka Minami-shi Minato-ku Osaka City Harman Co., Ltd.

Claims (2)

[Claims] 1. A tableware comprising a heating means for heating the inside of the cleaning tank and a temperature detecting means for detecting the temperature inside the cleaning tank, and the temperature detecting means controls the temperature of heating in the cleaning tank by the heating means. In the washer / dryer, the duty ratio of the energization to the heating means is changed at a predetermined temperature below the set temperature at which the energization to the heating means is cut off, and the ON time is lengthened at the predetermined temperature or lower and the predetermined temperature or higher. The dishwasher / dryer is characterized by shortening the on-time. 2. A tableware having a heating means for heating the inside of the cleaning tank and a temperature detecting means for detecting the temperature inside the cleaning tank, and the temperature detecting means controls the temperature of heating in the cleaning tank by the heating means. In the washer / dryer, a plurality of set temperatures that will cut off the energization to the heating means are provided, and the set temperature that is compared with the detected temperature immediately after the start of energization to the heating means becomes the comparison target from the next time onward. A dishwasher / dryer characterized in that the temperature is lower than the set temperature.