Dry heating protection control method for liquid electric heater

Abstract

A dry heating protection control method for a liquid electric heater relates to protection control methods for liquid electric heaters. The method includes steps: A, mounting a temperature controller on the liquid electric heater, serially connecting the temperature controller with a heater heating element and a control relay, and arranging detection modules at two ends of the temperature controller, wherein the detection module is used for detecting on and off of the temperature controller; B, allowing a microprocessor controlled by programs to perform a short-time heating program when the liquid electric heater is started for heating, namely allowing the heating element of the heater to heat in a short time and then stopping heating in a short time, wherein the heating time and the stop time are determined according to intrinsic power and the size of the heating element; and C, using the microprocessor to judge whether the liquid electric heater is in dry heating or not according to variation of on and off conditions of the temperature controller, and timely cutting off a heating power source of the heating element if the liquid electric heater is in dry heating. Using the dry heating protection control method can accurately control dry heating time, save the temperature sensor, overcome the defect that slow response of a mechanical temperature controller results in overhigh temperature of the heating element and influences the service life of the heating element, lower the requirement on control precision of the mechanical temperature controller, and reduce purchase cost of control circuit components.

Description

technical field [0001] The invention relates to small household appliances, in particular to a method for protection and control of a liquid electric heater. Background technique [0002] Existing liquid electric heaters generally use negative temperature coefficient temperature sensors, mechanical thermostats or a combination of the two to prevent dry burning. When the temperature sensed by the temperature sensor exceeds the temperature or the mechanical thermostat exceeds the temperature, the heating element is turned off to To achieve the protective effect, it is passive protection. Due to the slow response of the mechanical thermostat, and the heating element itself is in the process of starting the heating, due to the thermal inertia and thermal resistance of the heating element itself, the actual temperature of the heating element is higher than that detected by the temperature sensor or the mechanical bimetal thermostat. The protection temperature is much higher, res...

AI Technical Summary

Problems solved by technology

Due to the slow response of the mechanical thermostat, and the heating element itself is in the process of starting the heating, due to the thermal inertia and thermal resistance of the heating element itself, the actual temperature of the heating element is higher than that detected by the temperature sensor or the mechanical bimetal thermostat. The protection temperature is much higher, resulting in untimely protection and shortening the life of the heating element

Using a temperature sensor, due to the error of the sensor itself, the deviation of the installation position on the heating element, the process of the heating element itself, the amount of thermal paste, etc. have a great relationship, and because the temperature of the installation position is generally high, it is easy to fail. Certain risks, and increase the cost of the product

Using a mechanical thermostat, due to the slow response of the mechanical thermostat, it is difficult to solve the malfunction and timely protection at the same time

The protection time of the existing dry burning protection method is uncertain, and the protection is not timely

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