Heating medium circulation apparatus

Abstract

A heating medium circulation apparatus promptly detects an overheating abnormality of a heating medium caused by insufficient circulation. The heating medium is pumped by a pump in a predetermined direction in a closed-loop circuit connecting a heater and a heat dissipator. An outgoing temperature and a return temperature of the heating medium flowing out of and into the heater are detected. When a heat dissipation-based operation starts, the pump is activated, and heating is started. Heating is temporarily stopped when the outgoing temperature reaches a heating stop temperature. Heating is resumed when the outgoing temperature falls below a heating resumption temperature. An additional condition that the difference between the outgoing and return temperatures is less than a determination value can be added to the condition for resuming heating. An overheating abnormality is detected when the additional condition remains unsatisfied until a determination time elapses after heating is stopped.

1 . A heating medium circulation apparatus for circulating a heating medium between a heater configured to heat the heating medium and a heat dissipator configured to dissipate heat from the heating medium, the apparatus comprising:
 a circulation circuit being a closed-loop circuit connecting the heater and the heat dissipator;   a circulation pump configured to pump the heating medium in the circulation circuit in a predetermined direction;   an outgoing temperature sensor configured to detect a temperature of the heating medium flowing out of the heater;   a return temperature sensor configured to detect a temperature of the heating medium flowing into the heater;   a heating controller configured to control heating in the heater; and   an overheating abnormality detector configured to detect an overheating abnormality, the overheating abnormality being local overheating of the heating medium caused by insufficient circulation of the heating medium in the circulation circuit,   wherein the circulation pump is activated in response to a start of a heat dissipation-based operation and remains active during the heat dissipation-based operation, and the heat dissipation-based operation is an operation using heat dissipation performed by the heat dissipator,   the heating controller starts the heating in the heater in response to the start of the heat dissipation-based operation,   the heating controller temporarily stops the heating in the heater when a heating stop condition is satisfied, and the heating stop condition is that the temperature detected by the outgoing temperature sensor reaches a heating stop temperature,   the heating controller resumes the heating in the heater when a heating resumption condition is satisfied, the heating resumption condition is that the temperature detected by the outgoing temperature sensor or the temperature detected by the return temperature sensor decreases to a heating resumption temperature, the heating controller is configured to add an additional condition to the heating resumption condition, and the additional condition is that a temperature difference between the temperature detected by the outgoing temperature sensor and the temperature detected by the return temperature sensor is less than a determination value, and   the overheating abnormality detector detects the overheating abnormality when a detection condition is satisfied, and the detection condition is that the additional condition, when added to the heating resumption condition, remains unsatisfied until a predetermined determination time elapses from a time at which the heating in the heater is stopped in response to the heating stop condition being satisfied.   
     
     
         2 . The heating medium circulation apparatus according to  claim 1 , wherein
 the detection condition includes a further condition that an increasing gradient being a rate of increase per unit time of the temperature detected by the outgoing temperature sensor is higher than or equal to a predetermined determination gradient, and the overheating abnormality detector detects the overheating abnormality when the detection condition including the further condition is satisfied.   
     
     
         3 . The heating medium circulation apparatus according to  claim 2 , wherein
 the heating controller adds the additional condition to the heating resumption condition in response to the increasing gradient of the temperature detected by the outgoing temperature sensor being higher than or equal to the determination gradient.   
     
     
         4 . The heating medium circulation apparatus according to  claim 1 , wherein
 the detection condition includes a further condition that the temperature detected by the outgoing temperature sensor remains higher than an abnormality determination temperature for at least a specified time after the heating in the heater is stopped in response to the heating stop condition being satisfied, the abnormality determination temperature is higher than the heating stop temperature, and the overheating abnormality detector detects the overheating abnormality when the detection condition including the further condition is satisfied.   
     
     
         5 . The heating medium circulation apparatus according to  claim 4 , wherein
 the heating controller adds the additional condition to the heating resumption condition in response to the temperature detected by the outgoing temperature sensor remaining higher than the abnormality determination temperature for at least the specified time after the heating in the heater is stopped in response to the heating stop condition being satisfied.   
     
     
         6 . The heating medium circulation apparatus according to  claim 2 , wherein
 the detection condition includes a further condition that the temperature detected by the outgoing temperature sensor remains higher than an abnormality determination temperature for at least a specified time after the heating in the heater is stopped in response to the heating stop condition being satisfied, the abnormality determination temperature is higher than the heating stop temperature, and the overheating abnormality detector detects the overheating abnormality when the detection condition including the further condition is satisfied.   
     
     
         7 . The heating medium circulation apparatus according to  claim 6 , wherein
 the heating controller adds the additional condition to the heating resumption condition in response to the temperature detected by the outgoing temperature sensor remaining higher than the abnormality determination temperature for at least the specified time after the heating in the heater is stopped in response to the heating stop condition being satisfied.