JP7558096B2 - Cooking equipment - Google Patents

Description

The technology disclosed in this specification relates to a cooking device.

Patent Document 1 discloses a cooking device. The cooking device includes a burner, a heating chamber that heats an object to be heated with combustion gas from the burner, an exhaust duct through which exhaust gas from the heating chamber flows, an air passage disposed above the heating chamber and through which air flows in from the outside through the air intake port and flows out to the outside through the exhaust port, and a circuit board, a cooling fan, and a temperature detection means disposed in the air passage. The cooling fan is used to cool the circuit board. The temperature detection means detects the temperature in the air passage. An abnormality in the cooling fan is detected when the temperature detection means detects a high temperature.

JP 2020-153556 A

In cooking appliances such as those described above, when the power is turned off, the cooling fan may also stop accordingly. When the burner is ignited and the power is turned off to stop the cooling fan, the cooling fan stops while the temperature in the air passage remains high. If the power is then turned back on after a relatively short time has passed, the temperature detected by the temperature detection means becomes high. In such cases, even when there is no abnormality in the cooling fan, it may be erroneously determined that there is an abnormality in the cooling fan based on the detected temperature.

This specification discloses a technology that more accurately detects abnormalities in a cooling fan that cools a circuit board.

The cooking device disclosed in this specification includes a burner, a heating chamber that heats an object to be heated by combustion gas from the burner, an exhaust duct through which exhaust gas from the heating chamber flows, an air passage arranged above the heating chamber and through which air flows in from the outside through an air inlet and flows out to the outside through an exhaust port passes, a circuit board arranged in the air passage, a cooling fan arranged in the air passage, a temperature detection means arranged in the air passage, and a control unit. The control unit can execute a cooling fan normal operation control that operates the cooling fan at a normal rotation speed, and a cooling fan limited operation control that operates the cooling fan at a rotation speed lower than the normal rotation speed for a predetermined time from the ignition of the burner or a first detection time that is a predetermined time during the heating operation of the burner. When a first detection temperature, which is a detection temperature detected by the temperature detection means during the execution of the cooling fan limited operation control, satisfies a predetermined condition, the control unit determines that an abnormality has occurred in the cooling fan and reduces the firepower of the burner.

In the above-mentioned cooking device, when the first detection temperature during the execution of the cooling fan limited operation control satisfies a predetermined condition, it is determined that an abnormality has occurred in the cooling fan, and the heat of the burner is reduced. When the cooling fan is operating normally, the first detection temperature during the execution of the cooling fan limited operation control shows a behavior according to the rotation speed of the cooling fan. On the other hand, when an abnormality has occurred in the cooling fan, the first detection temperature during the execution of the cooling fan limited operation control shows a behavior unrelated to the rotation speed of the cooling fan. Therefore, by using the first detection temperature, it is possible to accurately determine whether or not there is an abnormality in the cooling fan even in a state where the detection temperature becomes high (for example, when the cooking device is reused immediately after use, etc.) .

In the cooking device disclosed in this specification, the predetermined condition may include that when the cooling fan normal operation control is executed immediately before the cooling fan limited operation control is executed, the judgment value calculated based on the second detection temperature, which is the detection temperature detected by the temperature detection means during the execution of the cooling fan normal operation control, and the first detection temperature is within a predetermined range. According to this configuration, the second detection temperature during the execution of the cooling fan normal operation control and the first detection temperature during the execution of the cooling fan limited operation control executed subsequently are used to judge whether the predetermined condition is satisfied. When the cooling fan is operating normally, the second detection temperature during the execution of the cooling fan normal operation control is less likely to rise, and the first detection temperature during the execution of the cooling fan limited operation control is more likely to rise. On the other hand, when an abnormality occurs in the cooling fan, there is no change in the ease of rise of the detection temperature (i.e., the second detection temperature and the first detection temperature) between the execution of the cooling fan normal operation control and the execution of the cooling fan limited operation control. Therefore, by using the first detection temperature and the second detection temperature, it is possible to accurately determine whether or not there is an abnormality in the cooling fan.

In the cooking device disclosed in this specification, the predetermined condition may include that when the cooling fan normal operation control is executed following the execution of the cooling fan limited operation control, the judgment value calculated based on the second detection temperature, which is the detection temperature detected by the temperature detection means during the execution of the cooling fan normal operation control, and the first detection temperature is within a predetermined range. According to this configuration, the first detection temperature during the execution of the cooling fan limited operation control and the second detection temperature during the execution of the cooling fan normal operation control executed subsequently thereto are used to judge whether the predetermined condition is satisfied. When the cooling fan is operating normally, the second detection temperature during the execution of the cooling fan normal operation control is less likely to rise, and the first detection temperature during the execution of the cooling fan limited operation control is more likely to rise. On the other hand, when an abnormality occurs in the cooling fan, there is no change in the ease with which the detection temperature (i.e., the second detection temperature and the first detection temperature) rises between the execution of the cooling fan normal operation control and the execution of the cooling fan limited operation control. Therefore, by using the first detection temperature and the second detection temperature, the presence or absence of an abnormality in the cooling fan can be accurately determined.

In the cooking device disclosed in this specification, the judgment value may be the difference between the time rate of change of the first detected temperature and the time rate of change of the second detected temperature. The predetermined condition may include the difference being smaller than a predetermined range. With this configuration, the difference between the first detected temperature and the second detected temperature can be appropriately compared.

FIG. 1 is a diagram showing a schematic configuration of a cooking device according to an embodiment of the present invention. 6 is a flowchart showing an example of a process for detecting an abnormality in a cooling fan. 6 is a flowchart showing an example of a process in a state where the temperature in the electrical equipment compartment is high (hot start state); FIG. 6 is a diagram for explaining a temperature change in the electrical equipment room during processing in a hot start state. 6 is a flowchart showing an example of a process in a state where the temperature inside the electrical equipment compartment is low (cold start state). FIG. 6 is a diagram for explaining a temperature change in the electrical equipment room during processing in a cold start state.

(Example)
The cooking device 10 of this embodiment shown in Fig. 1 is a convection oven for commercial use. The cooking device 10 includes a housing 12, a heating chamber 14, a burner chamber 16, a circulation fan chamber 18, and an electrical equipment chamber 20. The heating chamber 14, the burner chamber 16, the circulation fan chamber 18, and the electrical equipment chamber 20 are housed inside the housing 12.

The heating chamber 14 is equipped with multiple trays 22 arranged in a vertical line. An object to be heated W, such as food ingredients or cooking containers, can be placed on each tray 22. With the front door 24 open, the user can put the object to be heated W in and take it out of the heating chamber 14. The front door 24 can be opened and closed by rotating the lower end of the front door 24 back and forth relative to the housing 12 as a rotation axis.

The burner chamber 16 is disposed below the heating chamber 14. The burner chamber 16 is provided with a burner 26 that burns fuel gas. Fuel gas is supplied to the burner 26 from a gas supply pipe (not shown). The gas supply pipe is provided with a gas on-off valve and a gas flow rate control valve (not shown). When an igniter (not shown) performs an ignition operation with the gas on-off valve of the gas supply pipe open, the burner 26 ignites. The flame power of the burner 26 can be adjusted by adjusting the opening of the gas flow rate control valve of the gas supply pipe during combustion of the burner 26. When the gas on-off valve of the gas supply pipe is closed during combustion of the burner 26, the burner 26 is extinguished. The front end of the burner chamber 16 is provided with an air inlet 28 through which air flows in from the outside. The rear end of the burner chamber 16 is connected to the lower end of the combustion gas passage 30.

The combustion gas passage 30 extends vertically along the rear surface of the heating chamber 14. A filter 32 is disposed between the heating chamber 14 and the combustion gas passage 30. A circulation fan chamber 18 is disposed behind the combustion gas passage 30. The combustion gas passage 30 and the circulation fan chamber 18 are in communication with each other via an opening 34.

A circulation fan 36 is disposed in the circulation fan chamber 18. The circulation fan 36 is driven to rotate by a fan motor 38. The lower part of the circulation fan chamber 18 is connected to the rear end of the circulation passage 40. The front end of the circulation passage 40 opens at the bottom inside the heating chamber 14.

The front end of the exhaust passage 42 is connected to the top of the heating chamber 14. The rear end of the exhaust passage 42 is connected to the bottom end of the exhaust duct 44. The exhaust duct 44 extends in the vertical direction. The top end of the exhaust duct 44 opens into the cooling passage 46. The top end of the cooling passage 46 is connected to an exhaust port 48 formed on the top surface of the housing 12.

In the cooking device 10, when the circulation fan 36 is rotated and the burner 26 is burned, the combustion gas from the burner 26 flows from the burner chamber 16 through the combustion gas passage 30 into the circulation fan chamber 18, and is sent out to the bottom of the heating chamber 14 through the circulation passage 40. The combustion gas that flows into the heating chamber 14 flows around the object W to be heated placed on the tray 22, heating the object W. A part of the combustion gas in the heating chamber 14 is sucked into the combustion gas passage 30 through the filter 32 by the rotation of the circulation fan 36, and is sent out to the bottom of the heating chamber 14 again through the circulation fan chamber 18 and the circulation passage 40. The remaining combustion gas in the heating chamber 14 flows into the exhaust duct 44 through the exhaust passage 42, flows from the upper end of the exhaust duct 44 toward the exhaust port 48, and is discharged to the outside of the housing 12. The air for combustion in the burner 26 is drawn into the burner chamber 16 from outside the housing 12 through the air intake 28 by the rotation of the circulation fan 36.

The cooling passage 46 is disposed above the heating chamber 14, the combustion gas passage 30, the circulation fan chamber 18, and the exhaust passage 42. The cooling passage 46 covers the upper surfaces of the heating chamber 14 and the exhaust passage 42, and surrounds the exhaust duct 44. An air intake port 50 is formed at the front end of the cooling passage 46.

The front door 24 is equipped with an inner cooling passage 52 and an outer cooling passage 54. The inner cooling passage 52 is formed in a shape that covers the front surface of the heating chamber 14. The outer cooling passage 54 is formed in a shape that covers the front surface of the inner cooling passage 52. An air supply port 56 through which air flows in from the outside is formed at the lower end of the inner cooling passage 52. An air supply port 58 through which air flows in from the outside is formed at the lower end of the outer cooling passage 54. The upper end of the inner cooling passage 52 is connected to the outer cooling passage 54 through an opening 60. An exhaust port 62 is formed on the rear surface of the top of the outer cooling passage 54. The exhaust port 62 is located in a position that is close to and faces the air supply port 50 of the cooling passage 46 when the front door 24 is closed.

When the cooking device 10 heats the object W in the heating chamber 14 with the combustion gas, the air in the cooling passage 46 is pulled by the flow of exhaust gas discharged from the exhaust duct 44 to the exhaust port 48, and is also discharged to the exhaust port 48. This air flow causes air to flow into the air intake port 56 and the air intake port 58 of the front door 24. The air that flows into the air intake port 56 flows from the bottom to the top of the inner cooling passage 52, and then flows into the outer cooling passage 54 through the opening 60. The air that flows into the air intake port 58 flows from the bottom to the top of the outer cooling passage 54. The air flowing through the inner cooling passage 52 and the outer cooling passage 54 can prevent the front surface of the front door 24 from becoming too hot due to the heat from the heating chamber 14. The air that flows to the upper end of the outer cooling passage 54 is discharged from the exhaust port 62 and flows into the cooling passage 46 through the air intake port 50. The air that flows into the cooling passage 46 flows from the front to the rear along the top surface of the heating chamber 14, and is then exhausted through the exhaust port 48.

The electrical equipment room 20 is disposed above the heating chamber 14 and in front of the exhaust duct 44. A cooling passage 46 is interposed between the electrical equipment room 20 and the heating chamber 14. A cooling passage 46 is also interposed between the electrical equipment room 20 and the exhaust duct 44. An operation board 64 is disposed at the front end of the electrical equipment room 20. The operation board 64 is connected to an operation panel 66 provided on the front surface of the housing 12. The operation panel 66 is provided with a display unit (not shown) that displays the state of the heating cooker 10 to the user, and an operation unit (not shown) that receives operation input from the user to the heating cooker 10. The operation board 64 is a circuit board that controls the operation of the display unit of the operation panel 66 and detects operation input from the user to the operation unit of the operation panel 66. A control board 68 is disposed behind the operation board 64 of the electrical equipment room 20. The control board 68 is connected to the operation board 64. The control board 68 is a circuit board that controls the operation of each electrical component of the cooking appliance 10.

As described above, when the cooking device 10 heats the object W in the heating chamber 14 with combustion gas, air flows through the cooling passage 46 between the electrical equipment chamber 20 and the heating chamber 14. This prevents the electrical equipment chamber 20 from becoming too hot due to heat from the heating chamber 14. In addition, when the cooking device 10 heats the object W in the heating chamber 14 with combustion gas, air flows through the cooling passage 46 between the electrical equipment chamber 20 and the exhaust duct 44. This prevents the electrical equipment chamber 20 from becoming too hot due to heat from the exhaust duct 44.

The front end of the electrical equipment room 20 is connected to an air intake port 70 formed on the front surface of the housing 12. The rear end of the electrical equipment room 20 is connected to an exhaust port 72 formed on the top surface of the housing 12. A cooling fan 74 is disposed behind the control board 68 of the electrical equipment room 20. The cooling fan 74 is driven to rotate by a fan motor (not shown). When the cooling fan 74 rotates, air flows into the electrical equipment room 20 from the outside of the housing 12 through the air intake port 70, and air flows out of the electrical equipment room 20 to the outside of the housing 12 through the exhaust port 72. The air flow in the electrical equipment room 20 cools the operation board 64 and the control board 68 disposed inside the electrical equipment room 20. In addition, an inclined surface 76 inclined from the horizontal plane is provided at the lower part of the rear end of the electrical equipment room 20. A temperature sensor 78 is provided on the inclined surface 76. The temperature sensor 78 is positioned opposite the exhaust duct 44 across the cooling passage 46.

The process of detecting an abnormality in the cooling fan 74 will be described below with reference to Figures 2 to 6. In this embodiment, when the heating operation is started, it is detected whether or not an abnormality has occurred in the cooling fan 74. When the user issues an instruction to start the heating operation via the operation panel 66, the control board 68 executes the process shown in Figure 2.

When the start of the heating operation is instructed, the control board 68 judges whether the temperature detected by the temperature sensor 78 is equal to or lower than a predetermined temperature (e.g., 50°C) (S12). If only a short time has passed since the previous heating operation ended, the entire heating cooker 10 remains hot, and the temperature in the electrical equipment chamber 20 is also high. If the temperature in the electrical equipment chamber 20 is higher than the predetermined temperature (NO in step S12), not much time has passed since the previous heating operation ended, and the control board 68 judges that the temperature in the electrical equipment chamber 20 is high (hereinafter also referred to as a hot start state). Therefore, the control board 68 executes processing in the hot start state (S14). On the other hand, if the temperature in the electrical equipment chamber 20 is equal to or lower than the predetermined temperature (YES in step S12), time has passed since the previous heating operation ended, and the control board 68 judges that the temperature in the electrical equipment chamber 20 has become low (hereinafter also referred to as a cold start state). Therefore, the control board 68 executes processing in a cold start state (S16).

First, the processing in the hot start state will be described. When it is determined that the state is the hot start state (NO in step S12), the control board 68 ignites the burner 26 (S22) as shown in FIG. 3. This starts heating the object W to be heated in the heating chamber 14. Here, the cooling fan 74 is not driven and is stopped. Hereinafter, the control by the control board 68 to perform heating operation while driving the cooling fan 74 may be referred to as "cooling fan normal operation control", and the control by the control board 68 to perform heating operation without driving the cooling fan 74 may be referred to as "cooling fan limited operation control". Therefore, in the subsequent steps, cooling fan limited operation control is executed.

Next, the control board 68 acquires the temperature detected by the temperature sensor 78 (S24). As shown in FIG. 4, the control board 68 acquires the temperature T1 in the electrical equipment room 20 at time t1 when the burner 26 is ignited (i.e., when the heating operation starts).

As shown in FIG. 3, the control board 68 then waits until a predetermined time has elapsed since igniting the burner 26 (NO in step S26). Once the predetermined time has elapsed (YES in step S26), the control board 68 acquires the temperature detected by the temperature sensor 78 (S28). As shown in FIG. 4, the control board 68 acquires the temperature T2 inside the electrical equipment compartment 20 at time t2, a predetermined time after the start of the cooling fan limited operation control.

As shown in FIG. 3, the control board 68 then calculates the time rate of change Δ1 of the detected temperature during execution of the cooling fan limited operation control (S30) using the temperature T1 acquired in step S24 and the temperature T2 acquired in step S28. As shown in FIG. 4, the time rate of change Δ1 is, for example, the temperature gradient from time t1 to time t2.

As shown in FIG. 3, the control board 68 then drives the cooling fan 74 (S32). As a result, in the subsequent steps, the cooling fan normal operation control is executed. Next, the control board 68 acquires the temperature detected by the temperature sensor 78 (S34). Next, the control board 68 waits until a predetermined time has elapsed since the start of driving the cooling fan 74 (NO in step S36). When the predetermined time has elapsed (YES in step S36), the control board 68 acquires the temperature detected by the temperature sensor 78 (S38). The temperature acquired here is the temperature in the electrical equipment room 20 at a time (time t3 in FIG. 4) after the predetermined time has elapsed since the cooling fan normal operation control was changed to. If an abnormality occurs in the cooling fan 74 and the cooling fan 74 does not operate normally, the electrical equipment room 20 will not be cooled. For this reason, as shown by the dashed line at the bottom of Figure 4, if an abnormality occurs in the cooling fan 74, the temperature inside the electrical equipment chamber 20 will rise further during the predetermined time that elapses in step S34, and the temperature T3 at time t3 will be higher than the temperature T2 at time t2. On the other hand, as shown by the solid line at the bottom of Figure 4, if the cooling fan 74 operates normally, the temperature inside the electrical equipment chamber 20 will drop during the predetermined time that elapses, and the temperature T4 at time t3 will be lower than the temperature T3 at time t3 when the cooling fan 74 does not operate normally.

As shown in FIG. 3, the control board 68 then calculates the time rate of change Δ2 of the detected temperature during execution of the cooling fan normal operation control (S40) using the temperature acquired in step S34 (temperature T2 in FIG. 4) and the temperature acquired in step S38 (temperature T3 or temperature T4 in FIG. 4). As shown in FIG. 4, the time rate of change Δ2 is, for example, the temperature gradient between time t2 and time t3. When the cooling fan 74 does not operate normally, the temperature changes from temperature T2 to temperature T3, so the time rate of change Δ2 is large. On the other hand, when the cooling fan 74 operates normally, the temperature changes from temperature T2 to temperature T3, so the time rate of change Δ2 is small.

As shown in FIG. 3, the control board 68 then determines whether the absolute value of the difference between the time rate of change Δ1 of the detected temperature during the execution of the cooling fan limited operation control calculated in step S30 and the time rate of change Δ2 of the detected temperature during the execution of the cooling fan normal operation control calculated in step S40 is greater than a predetermined value (S42). The predetermined value is a value for determining whether the time rate of change Δ1 and the time rate of change Δ2 change little or much, and is stored in advance in the memory (not shown) of the control board 68. As shown by the dashed line at the bottom of FIG. 4, if the cooling fan 74 does not operate normally, the inside of the electrical equipment room 20 is not cooled even during the execution of the cooling fan normal operation control (between time t2 and time t3), and the temperature in the electrical equipment room 20 rises even during the execution of the cooling fan normal operation control (between time t2 and time t3) in the same way as during the execution of the cooling fan limited operation control (between time t1 and time t2). Therefore, there is almost no difference between the time rate of change Δ1 and the time rate of change Δ2. Therefore, if the absolute value of the difference between the time rate of change Δ1 and the time rate of change Δ2 is equal to or less than a predetermined value (NO in step S42), the control board 68 determines that an abnormality has occurred in the cooling fan 74. The control board 68 then extinguishes the burner 26 and stops the heating operation (S44). Thereafter, the control board 68 notifies the user via the operation panel 66 that the heating operation has ended abnormally (S46).

On the other hand, as shown by the solid line at the bottom of FIG. 4, when the cooling fan 74 operates normally, the interior of the electrical equipment room 20 is cooled during the execution of the cooling fan normal operation control (between time t2 and time t3), and the temperature in the electrical equipment room 20 drops or is less likely to rise during the execution of the cooling fan normal operation control (between time t2 and time t3) than during the execution of the cooling fan limited operation control (between time t1 and time t2). Therefore, the time change rate Δ2 is smaller than the time change rate Δ1, and the time change rates Δ1 and Δ2 are significantly different. Therefore, if the absolute value of the difference between the time change rates Δ1 and Δ2 is greater than a predetermined value (YES in step S42), the control board 68 determines that the cooling fan 74 is normal. Then, the control board 68 continues the heating operation (S48). In this embodiment, the time change rate Δ2 is the time change rate from when the cooling fan 74 starts to be driven until a predetermined time has elapsed (i.e., between time t2 and time t3 in FIG. 4), but is not limited to this configuration. For example, the time change rate Δ2 may be the time change rate from when a predetermined time (e.g., a first predetermined time) has elapsed since the cooling fan 74 is driven until a further predetermined time (e.g., a second predetermined time different from the first predetermined time) has elapsed (i.e., between time t2' and time t3 in FIG. 4).

Next, the process in the cold start state will be described. When it is determined that the cold start state has occurred (NO in step S12 in FIG. 2), the control board 68 ignites the burner 26 (S52), as shown in FIG. 5. The control board 68 also drives the cooling fan 74 (S54). As a result, normal operation control of the cooling fan is performed in the subsequent steps.

Next, the control board 68 acquires the temperature detected by the temperature sensor 78 (S56). As shown in FIG. 6, the control board 68 acquires the temperature T5 in the electrical equipment compartment 20 at time t4, which is the start of the heating operation.

As shown in FIG. 5, the control board 68 then waits until a predetermined time has elapsed since the start of the heating operation (NO in step S58). After the predetermined time has elapsed (YES in step S58), the control board 68 acquires the temperature detected by the temperature sensor 78 (S60). In the cold start state, the normal operation control of the cooling fan is executed simultaneously with the start of the heating operation. Therefore, as shown by the dashed line in the lower part of FIG. 6, if an abnormality occurs in the cooling fan 74 and the cooling fan 74 does not operate normally, the interior of the electrical equipment compartment 20 is not cooled and the temperature T6 at time t5 becomes high. On the other hand, as shown by the solid line in the lower part of FIG. 6, if the cooling fan 74 operates normally, the interior of the electrical equipment compartment 20 is cooled and the temperature T7 at time t5 becomes lower than the temperature T6.

As shown in FIG. 5, the control board 68 then uses the temperature acquired in step S56 (temperature T5 in FIG. 6) and the temperature acquired in step S60 (temperature T6 or temperature T7 in FIG. 6) to calculate the time rate of change Δ3 of the detected temperature when the cooling fan 74 is driven and the heating operation is performed (S62). As shown in FIG. 6, the time rate of change Δ3 is, for example, the temperature gradient between time t4 and time t5. As shown by the dashed line at the bottom of FIG. 6, when the cooling fan 74 does not operate normally, the temperature changes from temperature T5 to temperature T6, so the time rate of change Δ3 is large. On the other hand, as shown by the solid line at the bottom of FIG. 6, when the cooling fan 74 operates normally, the temperature changes from temperature T5 to temperature T7, so the time rate of change Δ3 is small.

As shown in FIG. 5, the control board 68 then stops driving the cooling fan 74 (S64). Therefore, in the following steps, the cooling fan limited operation control is executed. Next, the control board 68 acquires the temperature detected by the temperature sensor 78 (S66). Next, the control board 68 waits until a predetermined time has elapsed since the start of the cooling fan limited operation control (NO in step S68). When the predetermined time has elapsed (YES in step S68), the control board 68 acquires the temperature detected by the temperature sensor 78 (S70). The temperature acquired here is the temperature in the electrical equipment room 20 at a time (time t6 in FIG. 6) after the predetermined time has elapsed since the change to the cooling fan limited operation control. Therefore, regardless of whether an abnormality has occurred in the cooling fan 74, the temperature in the electrical equipment room 20 rises significantly. As shown in the lower part of FIG. 6, between time t5 and time t6, the temperature rise rate (slope) detected by temperature sensor 78 is the same when an abnormality occurs in cooling fan 74 (see the dashed line at the bottom of FIG. 6) and when cooling fan 74 is operating normally (see the solid line at the bottom of FIG. 6). When an abnormality occurs in cooling fan 74, temperature T6 at time t5 is high, so temperature T8 at time t6 is also high. On the other hand, when cooling fan 74 is operating normally, temperature T7 at time t5 is lower than temperature T6, so temperature T9 at time t6 is also lower than temperature T8.

As shown in FIG. 5, the control board 68 then calculates the time rate of change Δ4 of the detected temperature during execution of the cooling fan limited operation control (S72) using the temperature acquired in step S66 (temperature T6 or temperature T7 in FIG. 6) and the temperature acquired in step S70 (temperature T8 or temperature T9 in FIG. 6). As shown in FIG. 6, the time rate of change Δ4 is, for example, the temperature gradient from time t5 to time t6.

5, the control board 68 then determines whether the absolute value of the difference between the time rate of change Δ3 of the detected temperature during the execution of the cooling fan normal operation control calculated in step S62 and the time rate of change Δ4 of the detected temperature during the execution of the cooling fan limited operation control calculated in step S72 is greater than a predetermined value (S74). The predetermined value is a value for determining whether the time rate of change Δ3 and the time rate of change Δ4 change little or greatly, and is stored in advance in the memory (not shown) of the control board 68. In this embodiment, the predetermined value in the processing of the cold start state (the predetermined value used in step S74) is a value different from the predetermined value in the processing of the hot start state (the predetermined value used in step S42 in FIG. 3), but may be the same value. As shown by the dashed line at the bottom of FIG. 6, if the cooling fan 74 does not operate normally, the cooling fan 74 will not operate even during the execution of the cooling fan normal operation control, and the temperature in the electrical equipment room 20 will also rise significantly during this period (between time t4 and time t5). For this reason, there is almost no difference between the time rate of change Δ3 and the time rate of change Δ4. Therefore, if the absolute value of the difference between the time rate of change Δ3 and the time rate of change Δ4 is equal to or less than a predetermined value (NO in step S74), the control board 68 determines that an abnormality has occurred in the cooling fan 74. The control board 68 then extinguishes the burner 26 and stops the heating operation (S76). Thereafter, the control board 68 notifies the user via the operation panel 66 that the heating operation has ended abnormally (S78).

On the other hand, as shown by the solid line at the bottom of FIG. 6, when the cooling fan 74 is driven normally, the inside of the electrical equipment room 20 is cooled during the execution of the cooling fan normal operation control (between time t4 and time t5), and the temperature inside the electrical equipment room 20 is less likely to rise or falls. For this reason, the time change rate Δ3 becomes smaller than the time change rate Δ4, and the time change rates Δ3 and Δ4 are significantly different. Therefore, if the absolute value of the difference between the time change rates Δ3 and Δ4 is greater than a predetermined value (YES in step S74), the control board 68 determines that the cooling fan 74 is normal. Then, the control board 68 continues the heating operation (S80). In this embodiment, the time change rate Δ4 is the time change rate from when the cooling fan 74 is stopped until a predetermined time has elapsed (i.e., between time t5 and time t6 in FIG. 6), but is not limited to such a configuration. For example, the time rate of change Δ4 may be the time rate of change from when a predetermined time (e.g., a first predetermined time) has elapsed since the cooling fan 74 was stopped until a further predetermined time (e.g., a second predetermined time different from the first predetermined time) has elapsed (i.e., between time t5' and time t6 in FIG. 6).

In this embodiment, when the heating operation starts, the cooling fan limited operation control and the cooling fan normal operation control are executed. Then, the temperature rise rate in the electrical equipment compartment 20 while each control is executed is compared, thereby detecting an abnormality in the cooling fan 74. Therefore, it is possible to accurately detect whether the cooling fan 74 is operating normally.

In this embodiment, the predetermined value used in step S42 and step S74 is a constant value stored in advance in the memory (not shown) of the control board 68, but is not limited to this configuration. For example, the predetermined value used in step S42 and step S74 may be corrected based on the temperature acquired when the process for detecting an abnormality in the cooling fan 74 was executed the previous time. The acquired temperature is the temperature acquired in the process of steps S24, S28, S34, and S38 in FIG. 3 when the process for the hot start state is executed, and is the temperature acquired in the process of steps S56, S60, S66, and S70 in FIG. 5 when the process for the cold start state is executed. The temperature acquired in these processes varies depending on the external condition of the cooking appliance 10, such as the outside air temperature. By correcting the predetermined value using the acquired temperature, the process for detecting an abnormality in the cooling fan 74 can be executed taking into account the external condition of the cooking appliance 10. Therefore, the abnormality in the cooling fan 74 can be detected more accurately.

In addition, in this embodiment, when the heating operation is started, the above process is executed to detect whether the cooling fan 74 is operating normally, but the present invention is not limited to this configuration. The above process may be executed at a timing other than the start of the heating operation to detect whether the cooling fan 74 is operating normally, and for example, the above process may be executed after a predetermined time has elapsed since the start of the heating operation (i.e., in the middle or end of the heating operation).

In addition, in this embodiment, in the cooling fan limited operation control, the heating operation is performed without driving the cooling fan 74, but this configuration is not limited. In the cooling fan limited operation control, the cooling fan 74 may be driven at a rotation speed lower than the rotation speed (normal rotation speed) in the cooling fan normal operation control.

In addition, in this embodiment, in order to detect whether the cooling fan 74 is operating normally, in the processing of the hot start state, the cooling fan limited operation control is executed first, and then the cooling fan normal operation control is executed, and in the processing of the cold start state, the cooling fan normal operation control is executed first, but this configuration is not limited. For example, in the hot start state, the cooling fan limited operation control may be executed first, as in the processing of the cold start state shown in FIG. 5. Also, in the cold start state, the cooling fan normal operation control may be executed first, as in the processing of the hot start state shown in FIG. 3.

Notes regarding the cooking device 10 described in the embodiment are as follows. The electrical equipment chamber 20 in the embodiment is an example of an "air passage", the operation board 64 and the control board 68 are an example of a "circuit board", the control board 68 is an example of a "control unit", and the temperature sensor 78 is an example of a "temperature detection means".

Although the embodiments have been described in detail above, they are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. The technical elements described in this specification or drawings exert technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology exemplified in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of those objectives is itself technically useful.

10: Cooking device 12: Housing 14: Heating chamber 16: Burner chamber 18: Circulation fan chamber 20: Electrical equipment chamber 22: Tray 24: Front door 26: Burner 28: Air inlet 30: Combustion gas passage 32: Filter 34: Opening 36: Circulation fan 38: Fan motor 40: Circulation passage 42: Exhaust passage 44: Exhaust duct 46: Cooling passage 48: Exhaust port 50: Air inlet 52: Inner cooling passage 54: Outer cooling passage 56: Air inlet 58: Air inlet 60: Opening 62: Exhaust port 64: Operation board 66: Operation panel 68: Control board 70: Air inlet 72: Exhaust port 74: Cooling fan 76: Inclined surface 78: Temperature sensor

Claims (4)

Burna and
A heating chamber for heating an object to be heated by the combustion gas from the burner;
An exhaust duct through which exhaust gas from the heating chamber flows;
an air passage disposed above the heating chamber, through which air flows in from the outside through an air supply port and flows out to the outside through an air exhaust port;
a circuit board disposed within the air passage;
A cooling fan disposed within the air passage;
A temperature detection means disposed within the air passage;
A control unit,
The control unit is capable of executing a cooling fan normal operation control for operating the cooling fan at a normal rotation speed, and a cooling fan limited operation control for operating the cooling fan at a rotation speed lower than the normal rotation speed for a predetermined time from ignition of the burner or a first detection time that is a predetermined time during a heating operation of the burner,
When a first detection temperature, which is a detection temperature detected by the temperature detection means while the cooling fan limited operation control is being executed, satisfies a predetermined condition, the control unit determines that an abnormality has occurred in the cooling fan and reduces the flame power of the burner. The cooking device according to claim 1, wherein the predetermined condition includes that when the cooling fan normal operation control is executed immediately before the cooling fan limited operation control is executed, a judgment value calculated based on the first detection temperature and a second detection temperature detected by the temperature detection means during the execution of the cooling fan normal operation control is within a predetermined range. The cooking device according to claim 1, wherein the predetermined condition includes that when the cooling fan normal operation control is executed subsequently to the execution of the cooling fan limited operation control, a judgment value calculated based on the second detection temperature, which is a detection temperature detected by the temperature detection means during the execution of the cooling fan normal operation control, and the first detection temperature, is within a predetermined range. the determination value is a difference between a time rate of change of the first detected temperature and a time rate of change of the second detected temperature,
The cooking device according to claim 2 or 3, wherein the predetermined condition includes that the difference is smaller than a predetermined range.

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