JP4098733B2 - Overheat prevention device in stove - Google Patents

Description

The present invention relates to a desuperheater in stove with pan bottom temperature sensor for stove for detecting the temperature of contact with the cooking container on the bottom surface of the cooking container.

  Conventionally, in order to prevent ignition of oil in the cooking container during frying, a pan bottom temperature sensor that detects the temperature of the cooking container is provided in contact with the bottom surface of the cooking container, and the temperature detected by the pan bottom temperature sensor is a predetermined upper limit temperature. It is known that the combustion of the burner that heats the cooking vessel is stopped or the amount of combustion is reduced when the temperature rises. Here, when the amount of oil in the cooking container is small, the oil may ignite even if the temperature detected by the pan bottom temperature sensor is relatively low. Therefore, the upper limit temperature is variably set according to the rising speed of the temperature detected by the pan bottom temperature sensor in a predetermined temperature range.For example, when the rising speed of the temperature detected by the pan bottom temperature sensor is equal to or higher than the predetermined speed, the amount of oil is small. It is also known that the upper limit temperature is set lower than when it is determined (see, for example, Patent Document 1).

  By the way, when the burner is an annular internal flame type burner having an inward flame hole, the pan bottom temperature sensor arranged at the center of the burner is easily affected by the heat from the burner. Then, the temperature detected by the pan bottom temperature sensor is greatly deviated from the actual temperature of the cooking container to a higher temperature side, so that the burning of the burner is stopped although the actual temperature of the cooking container is low.

  Therefore, conventionally, the bottom of the pan is provided with an inner cylinder whose upper end is closed by a heat collecting plate that abuts the bottom surface of the cooking container, and an outer cylinder that surrounds the inner cylinder, and a temperature detection element such as a thermistor is attached to the lower surface of the heat collecting plate A temperature sensor is known (see, for example, Patent Document 2). According to this, the space between the outer cylinder and the inner cylinder acts as a heat insulating space, and the thermal influence from the burner on the temperature detection element is reduced.

However, even if such a pan-bottom temperature sensor with an outer cylinder is used, if the internal flame burner is burned with a strong heating power, the thermal effect from the burner on the temperature sensing element increases, and the temperature detected by the pan-bottom temperature sensor There is a case where the temperature detected by the temperature detecting element is greatly shifted from the actual temperature of the cooking container to the high temperature side. Here, if the upper limit temperature is set to a high value in consideration of the heat effect of the burner, premature disconnection can be prevented, but with this, the heat effect of the burner is small, and the temperature detected by the temperature detection element and the actual cooking container If the temperature difference is small, the oil in the cooking container will be overheated. And since the heat effect of a burner cannot be grasped | ascertained with a pan bottom temperature sensor, it is difficult to prevent oil overheating reliably and to prevent premature cutting.
Japanese Patent Laid-Open No. 5-44939 (paragraphs 0048 and 0049, FIG. 16) Japanese Patent Laid-Open No. 11-201461 (paragraph 0011, FIG. 3)

In view of the above points, by using the stove pan bottom temperature sensor capable of grasping the influence of heat from the burner to understand the influence of heat from the burner, the overheating prevention and early breakage prevention It is a challenge to provide a desuperheater in the so attained the compatibility stove.

In order to solve the above-described problem, the present invention includes an inner cylinder whose upper end is closed by a heat collecting plate that contacts the bottom surface of the cooking vessel, and an outer cylinder that surrounds the inner cylinder, and a first temperature is provided on the lower surface of the heat collecting plate. An overheating prevention device in a stove provided with a pan bottom temperature sensor to which a detection element is attached, and when a detected temperature of the first temperature detection element rises to a predetermined upper limit temperature, combustion of a burner that heats a cooking vessel is performed. A bottom of a pot comprising combustion limiting means for stopping or reducing the amount of combustion, and upper limit temperature setting means for variably setting an upper limit temperature in accordance with an increase rate in a predetermined temperature range of the temperature detected by the first temperature detection element A temperature sensor having a second temperature detecting element attached to the upper inner surface of the outer cylinder is used, and the upper limit temperature setting means is not used when the rising speed of the detected temperature of the first temperature detecting element is equal to or higher than a predetermined speed. Sometimes While the upper limit temperature is set low, the detected temperature of the first temperature detecting element is higher than the detected temperature of the second temperature detecting element even if the rising speed of the detected temperature of the first temperature detecting element is less than a predetermined speed. When the temperature is high, the upper limit temperature is set to be equal to that when the rising speed of the temperature detected by the first temperature detecting element is equal to or higher than a predetermined speed .

  The second temperature detection element of the pan bottom temperature sensor of the present invention is more susceptible to the heat effect of the burner than the first temperature detection element. Therefore, when the thermal effect of the burner on the pan bottom temperature sensor becomes large and the detected temperature of the first temperature detecting element deviates greatly to the higher temperature side than the actual temperature of the cooking container, the detected temperature of the second temperature detecting element is the first It becomes higher than the detection temperature of 1 temperature detection element. On the other hand, since the second temperature detection element is not affected by the heat from the cooking container, the heat influence from the burner is small, and the difference between the first temperature detection element and the actual temperature of the cooking container is small. The detected temperature of the second temperature detecting element is lower than the detected temperature of the first temperature detecting element. Therefore, it is possible to grasp the thermal effect of the burner based on the magnitude relationship between the detected temperature of the first temperature detecting element and the detected temperature of the second temperature detecting element.

  Then, as in the overheat prevention device of the present invention, the upper limit temperature is set according to the rising speed of the detection temperature of the first temperature detection element, and the detection temperature of the first temperature detection element and the detection temperature of the second temperature detection element are set. If it is changed according to the magnitude relationship, the overheating of the contents such as oil in the cooking container can be surely prevented, and premature cutting can be prevented.

That is , when the upper limit temperature is set lower than when the temperature increase rate of the detected temperature of the first temperature detection element is equal to or higher than a predetermined speed, the rate of increase of the detected temperature of the first temperature detection element is set according to the present invention. If the detected temperature of the first temperature sensing element is higher than the detected temperature of the second temperature sensing element (in this state, the detected temperature of the first temperature sensing element and the cooking container the actual difference between the temperature lower), because the maximum temperature rise rate of the temperature detected by the first temperature sensing element is configured to set equal to the time is equal to or higher than the predetermined speed, the contents of the cooking vessel Can be reliably prevented from overheating. According to this configuration, the rate of increase in the detection temperature of the first temperature detection element is less than the predetermined rate, and the detection temperature of the second temperature detection element is higher than the detection temperature of the first temperature detection element. Sometimes (in this state, the difference between the temperature detected by the first temperature detecting element and the actual temperature of the cooking container is large), the upper limit temperature is set high, and premature disconnection is prevented.

  In the embodiment described later, the combustion restriction means corresponds to the processing in steps S15 and S16 in FIG. 2, and the upper limit temperature setting means corresponds to steps S1 to S14 in FIG. It is processing of.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. 1 is a cross-sectional view of an example of a stove provided with a pan bottom temperature sensor according to the present invention, FIG. 2 is a flowchart showing overheat prevention control in the stove of FIG. 1, and FIG. 3 is a first and second temperature detection of the pan bottom temperature sensor. It is a graph which shows the change of the detection temperature of an element, and the actual temperature of oil.

  With reference to FIG. 1, 1 is a top plate which covers the upper surface of a stove main body (not shown), and is formed of heat resistant glass such as ceramic glass. The top plate 1 is provided with a burner opening 2, and a burner 3 is disposed in the stove body so as to face the burner opening 2. Then, the cooking container P placed on the top plate 1 via the virtues 4 is heated by the flame of the burner 3 rising through the burner opening 2. The burner 3 is constituted by an internal flame type burner formed by forming a large number of inward flame holes 3b in an annular burner body 3a. The burner 3 is provided with a thermocouple 3c for detecting a flame, an ignition electrode (not shown), and a secondary air guide 5 positioned above the burner body 3a. Further, a protective member 2a for preventing cracking is attached to the opening edge of the burner opening 2.

  Below the space surrounded by the burner main body 3a, an annular juice receiving tray 6 that receives the spillage falling from the burner opening 2 is arranged. In the inner circumferential space of the soup pan 6, a longitudinal support pipe 7 is arranged in the vertical direction fixed to the stove body, and the pan bottom temperature sensor 8 is supported by the support pipe 7. A heat shield cylinder 9 surrounding the pan bottom temperature sensor 8 is formed integrally with the soup pan 6 so that the flame and hot air of the burner 3 do not reach the pan bottom temperature sensor 8.

  The pan bottom temperature sensor 8 includes a heat collecting plate 80 that comes into contact with the bottom surface of the cooking container P, and a first temperature detecting element 81 made of a thermistor attached to the lower surface of the heat collecting plate 80. Then, the temperature of the cooking container P is detected by the first temperature detection element 81 via the heat collecting plate 80. Further, in order to eliminate the influence of the radiant heat from the heat shield cylinder 9 on the first temperature detection element 81, the pot bottom temperature sensor 8 surrounds the inner cylinder 82 and the inner cylinder 82 whose upper ends are closed by the heat collecting plate 80. An outer cylinder 83 is provided. The inner cylinder 82 and the outer cylinder 83 are caulked and fixed to each other at their lower ends. The inner cylinder 82 is slidably fitted on a spring receiver 7 a attached to the upper end of the support pipe 7. A spring 84 is interposed between the spring receiver 7a and a spring receiver 82a attached to the upper portion of the inner cylinder 82, and the pan bottom temperature sensor 8 is urged upward and supported by the spring 84 with respect to the support pipe 7. Yes. Therefore, when the cooking container P is placed on the Gotoku 4, the heat collecting plate 80 reliably contacts the bottom surface of the cooking container P by the biasing force of the spring 84.

  At the upper end of the outer cylinder 83, a lid portion 83a is provided for making the space between the outer cylinder 83 and the inner cylinder 82 a substantially closed heat insulating space. The lid 83 a is not in contact with the inner cylinder 82 and the heat collecting plate 80, and prevents the heat from the outer cylinder 83 that receives radiant heat from the heat shield cylinder 9 from being transmitted to the first temperature detection element 81. I can do it.

  However, even if the outer cylinder 83 is provided in this manner, the first temperature detecting element 81 cannot be completely prevented from being affected by the radiant heat from the heat shield cylinder 9 or the heat from the flame of the burner 3. In particular, the position of the upper end of the heat shield tube 9 is such that the heat shield tube 9 does not come into contact with the bottom surface of the container when a cooking container such as a wok is used, and the stability of the container is not impaired. In addition, the gap is set lower than the upper edge of the virtues 4, so that there is a gap between the upper end of the heat shield cylinder 9 and the bottom surface of the cooking vessel P, and the combustion hot air of the burner 3 enters the gap, and the first The temperature detection element 81 may be affected by heat from the burner 3.

Therefore, the pan temperature sensor 8 is provided with a second temperature detection element 85 made of a thermistor or the like attached to the upper inner surface of the outer cylinder 83 , and the second temperature detection element 85 causes a thermal effect from the burner 3 and the heat shield cylinder 9. To be able to grasp. Of course, the second temperature detecting element 85 is positioned below the heat collecting plate 80 and does not contact the bottom surface of the cooking container P. The lead wire 85a of the second temperature detection element 85 is inserted into the inner cylinder 82 through a hole formed in a portion above the spring receiver 82a of the inner cylinder 82, and together with the lead wire 81a of the first temperature detection element 81. It is connected to the controller 10 through the support pipe 7.

  When fried food cooking is performed, the controller 10 is a solenoid valve 11 provided in the gas supply path to the burner 3 when the temperature detected by the first temperature detecting element 81 of the pan bottom temperature sensor 8 rises to a predetermined upper limit temperature. Is closed to stop the combustion of the burner 3. The details of the overheat prevention control will be described below with reference to FIG. The controller 10 has a relatively low first set temperature YT1 (eg, 270 ° C.), an intermediate second set temperature YT2 (eg, 280 ° C.), and a relatively high third set temperature YT3 (eg, the upper limit temperature). 290 ° C.). Further, in the overheat prevention control, in order to estimate the amount of oil in the cooking container P, the detection temperature TH1 of the first temperature detection element 81 in the first temperature range determined based on the first set temperature YT1 is set. The rising speed and the rising speed of the detected temperature TH1 of the first temperature detecting element 81 in the second temperature range determined with the second set temperature YT2 as a reference are measured. Then, two set temperature differences ΔT1a (for example, 40 ° C.) and ΔT1b (for example, 20 ° C.) for defining the first temperature range and two set temperature differences ΔT2a (for example, for defining the second temperature range) 40 ° C.) and ΔT2b (for example, 20 ° C.) are stored in the controller 10.

  In the overheat prevention control, first, in step S1, whether or not the detected temperature TH1 of the first temperature detecting element 81 is equal to or higher than a temperature (lower limit of the first temperature range) lower than the first set temperature YT1 by ΔT1a. Is determined. When TH1 ≧ YT1−ΔT1a, the time measuring operation of the first timer is started in step S2. Next, in step S3, it is determined whether or not the detected temperature TH1 of the first temperature detecting element 81 is equal to or higher than a temperature lower than the second set temperature YT2 by ΔT2a (the lower limit value of the second temperature range), When TH1 ≧ YT2−ΔT2a, the timing operation of the second timer is started in step S4.

  Next, in step S5, it is determined whether or not the detected temperature TH1 of the first temperature detecting element 81 is equal to or higher than a temperature lower than the first set temperature YT1 by ΔT1b (the upper limit value of the first temperature range). When TH1 ≧ YT1−ΔT1b, the timing operation of the first timer is terminated in step S6. Therefore, the time t1 counted by the first timer is equal to the time required for the detected temperature TH1 of the first temperature detecting element 81 to rise from the lower limit value to the upper limit value of the first temperature range, This is a parameter representing the rising speed of the detected temperature TH1 of the first temperature detecting element 81 in the temperature range. Next, in step S7, it is determined whether or not the time t1 of the first timer is equal to or shorter than a predetermined set time Yt1 (for example, 20 seconds), that is, the detected temperature TH1 of the first temperature detecting element 81 in the first temperature range. It is determined whether or not the rising speed is equal to or higher than a predetermined speed. If t1 ≦ Yt1, it is determined that the amount of oil in the cooking container P is small, and the upper limit temperature Tmax is set to the first set temperature YT1 in step S8.

  When t1> Yt1, the magnitude relationship between the detected temperature TH1 of the first temperature detecting element 81 and the detected temperature TH2 of the second temperature detecting element 85 is determined in step S9. Each line of A1, A2, and A3 in FIG. 3 indicates the detected temperature TH1 and the second temperature of the first temperature detecting element 8 when 1 liter of oil is put in an aluminum pan and the burner 3 is burned with strong fire. The detection temperature TH2 of the detection element 85 and the actual temperature of the oil are shown, and the lines B1, B2, and B3 in the figure show that 1 liter of oil is put in an aluminum pan and the burner 3 is set to medium heat ( The detected temperature TH1 of the first temperature detecting element 8, the detected temperature TH2 of the second temperature detecting element 85, and the actual temperature of the oil when burned at a heating power of about 70% of the strong fire) are shown. In medium heat, the thermal effect from the burner 3 on the first temperature detection element 81 is small, the difference between the detected temperature TH1 of the first temperature detection element 81 and the actual temperature of the oil is small, and the first The detection temperature TH1 of the temperature detection element 81 is higher than the detection temperature TH2 of the second temperature detection element 85. On the other hand, in a strong fire, the thermal effect from the burner 3 on the first temperature detection element 81 is increased, and the difference between the detection temperature TH1 of the first temperature detection element 81 and the actual temperature of the oil is increased. The detection temperature TH2 of the second temperature detection element 85 is higher than the detection temperature TH1 of the first temperature detection element 81. Since the amount of oil is as large as 1 liter, the rising speed of the detected temperature TH1 of the first temperature detecting element 8 in the temperature range is slower than the predetermined speed in both high and medium fires.

  If it is determined in step S9 that TH1> TH2, the process proceeds to step S8, where the upper limit temperature Tmax is set to the first set temperature YT1. If it is determined in step S9 that TH2 ≧ TH1, the process proceeds to step S10, in which the detected temperature TH1 of the first temperature detecting element 81 is lower than the second set temperature YT2 by ΔT2b (second temperature range). It is determined whether or not the upper limit value is exceeded. Then, when TH1 ≧ YT2−ΔT2b, the time measuring operation of the second timer is terminated in step S11. Accordingly, the time t2 measured by the second timer is equal to the time required for the detected temperature TH1 of the first temperature detecting element 81 to rise from the lower limit value to the upper limit value of the second temperature range. Next, in step S12, it is determined whether or not the time t2 of the second timer is equal to or shorter than a predetermined set time Yt2 (for example, 30 seconds). If t2 ≦ Yt2, it is determined that the amount of oil in the cooking container P is not as much as the left, and the upper limit temperature Tmax is set to the second set temperature YT2 in step S13. If t2> Yt2, Then, it is determined that the amount of oil in the cooking container P is large, and the upper limit temperature Tmax is set to the third set temperature YT3 in step S14.

  When the upper limit temperature Tmax is set in steps S8, S13, and S14, the process proceeds to step S15 to determine whether or not the detected temperature TH1 of the first temperature detecting element 81 is equal to or higher than the upper limit temperature Tmax. When TH1 ≧ Tmax is established, the solenoid valve 11 is closed in step S16, and combustion of the burner 3 is stopped.

  According to the above control, even when the time t1 of the first timer is longer than the predetermined time Yt1, when the detected temperature TH1 of the first temperature detecting element 81 is higher than the detected temperature TH2 of the second temperature detecting element 85, The combustion of the burner 3 is stopped when the detected temperature TH1 of the first temperature detecting element 81 rises to the first set temperature YT1. Here, TH1> TH2 is satisfied when the thermal effect of the burner 3 on the first temperature detecting element 81 is small and the difference between the detected temperature TH1 of the first temperature detecting element 81 and the actual temperature of the oil is also small. By stopping the combustion of the burner 3 at the relatively low first set temperature YT1, overheating of the oil is prevented.

  On the other hand, when the detection temperature TH2 of the second temperature detection element 85 is equal to or higher than the detection temperature TH1 of the first temperature detection element 81, the detection temperature TH1 of the first temperature detection element 81 is the second set temperature YT2. Alternatively, the combustion of the burner 3 is stopped when the temperature rises to the third set temperature YT3. Here, TH2 ≧ TH1 is because the thermal effect of the burner 3 on the first temperature detecting element 81 is large, and the detected temperature TH1 of the first temperature detecting element 81 is greatly shifted to the higher temperature side than the actual temperature of oil. The combustion of the burner 3 is stopped at a relatively high second and third set temperatures YT2 and YT3, so that the combustion of the burner 3 is stopped even though the oil is not overheated. Is prevented.

  As described above, by using the pan bottom temperature sensor 8 including the second temperature detection element 85 between the inner cylinder 82 and the outer cylinder 83, overheating in consideration of the thermal effect of the burner 3 on the first temperature detection element 81 is considered. Preventive control can be performed to achieve both overheating prevention and premature disconnection prevention.

  In the above embodiment, the combustion of the burner 3 is stopped when the detected temperature TH1 of the first temperature detecting element 81 rises to the upper limit temperature Tmax. However, the amount of combustion of the burner 3 is reduced to overheat the oil. It is also possible to prevent this. In the above embodiment, the upper limit temperature Tmax can be variably set in three stages of the first set temperature YT1, the second set temperature YT2, and the third set temperature YT3. However, the upper limit temperature Tmax is higher than the first set temperature YT1. It is also possible to variably set in two stages with the second set temperature YT2. In this case, the steps S3, S4, S10 to S12, and S14 are unnecessary.

  In the above embodiment, only the magnitude of the detected temperature TH1 of the first temperature detecting element 81 and the detected temperature TH2 of the second temperature detecting element 85 is determined, but when TH2> TH1, TH2 It is also possible to set the upper limit temperature Tmax higher as the temperature difference increases in accordance with the temperature difference between TH1 and TH1.

Sectional drawing of an example of a stove provided with the pan bottom temperature sensor concerning this invention. FIG. 2 is a flowchart showing overheat prevention control in the stove of FIG. FIG. 3 is a graph showing changes in the detected temperature of the first and second temperature detecting elements of the pan bottom temperature sensor and the actual temperature of the oil.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 3 ... Burner, 8 ... Pan bottom temperature sensor, 80 ... Heat collecting plate, 81 ... 1st temperature detection element, 82 ... Inner cylinder, 83 ... Outer cylinder, 85 ... 2nd temperature detection element, 10 ... Controller (combustion restriction | limiting) Means, upper limit temperature setting means), P ... cooking container.

Claims (1)

A pan bottom temperature sensor is provided which includes an inner cylinder whose upper end is closed by a heat collecting plate abutting against the bottom surface of the cooking container, and an outer cylinder surrounding the inner cylinder, and a first temperature detecting element is attached to the lower surface of the heat collecting plate. An overheat prevention device in a stove,
Combustion limiting means for stopping the combustion of the burner for heating the cooking container or reducing the amount of combustion when the detection temperature of the first temperature detection element rises to a predetermined upper limit temperature, and detection of the first temperature detection element With an upper limit temperature setting means for variably setting the upper limit temperature according to the rate of increase in temperature within a predetermined temperature range,
The pan bottom temperature sensor is provided with a second temperature detecting element attached to the upper inner surface of the outer cylinder, and the upper limit temperature setting means is more when the detected temperature rise rate of the first temperature detecting element is equal to or higher than a predetermined speed. In addition, the upper limit temperature is set low, and the detected temperature of the first temperature detecting element is higher than the detected temperature of the second temperature detecting element even if the rising speed of the detected temperature of the first temperature detecting element is less than a predetermined speed. When the temperature is higher than the upper limit temperature, the upper temperature limit is set to be equal to that when the detected temperature rise rate of the first temperature detecting element is equal to or higher than a predetermined speed .

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