Patent Description:
Cooking appliances are used to cook food, and are installed in the kitchen to cook food according to a user's intention. The cooking appliances can be classified in various ways, based on a heat source or a type, and the sort of fuel.

Additionally, the cooking appliances can be categorized into an open type cooking appliance in which food is placed in an open space, and a sealed type cooking appliance in which food is placed in a closed space, based on a way of cooking food. The sealed type cooking appliance includes an oven, a microwave oven and the like, and the open type cooking appliance includes a cooktop, a hob, a griddle and the like.

In the sealed type cooking appliance, a space, in which food is placed, is shielded, and the shielded space is heated to cook food. The sealed type cooking appliance is provided with a cooking space in which food is placed and which is shielded when the food is cooked. In the cooking space, food is actually cooked.

The sealed type cooking appliance is provided with a rotatable door that optionally opens and closes the cooking space. The rotatable door is installed at a main body by a door hinge provided between the main body, having the cooking space therein, and the door, and can rotate with respect to a body portion where the door and the main body are coupled through the door hinge to selectively open and close the cooking space.

A heat source is disposed in an inner space of the cooking space opened and closed by the door, to heat the cooking space. The heat source includes a gas burner or an electric heater and the like.

The cooking space includes an electronic component space in an upper portion thereof. In the electronic component space, electronic components required for operating the sealed type cooking appliance can be disposed. The electronic component space is formed as a space separate from the cooking space.

In the electronic component space, a cooling fan for cooling the electronic component space is disposed. The cooling fan can be provided in the form of a centrifugal fan such as a sirocco fan, and can be disposed eccentrically to a rear of the electronic component space. The cooling fan can suction external air to cool an inside of the electronic component space and can forcibly blow hot air in the electronic component space out of the sealed type cooking appliance to cool the electronic component space.

When the cooling fan is out of order, the electronic component space cannot be cooled properly. This causes an excessive increase in temperatures of electronic components in the electronic component space and a failure of the electronic components.

<CIT> discloses an operating method for electric fan unit of cooking appliance. <CIT> discloses an oven which comprises a thermal heating element having cooking area with an adjacent switching area for controlling the oven operation. <CIT> discloses an oven which has a ventilation system capable of providing reduced temperature, where low moisture exhaust air is provided. <CIT> discloses a fan apparency arrangement for an appliance having a cooling fan for moving cooling air through an airflow pathway.

The present disclosure is directed to a cooking appliance and a method for controlling the same having an improved structure in which a failure of a cooling fan may be quickly found.

The present disclosure is also directed to a cooking appliance and a method for controlling the same having an improved structure in which a failure of an electronic component, caused by overheating, may be prevented.

The present disclosure is also directed to a method for controlling a cooking appliance, which may help to find a failure of the cooling fan quickly and may be applied to various types of ovens having different sizes of a cooking space and heat generating capacity.

The present disclosure is also directed to a method for controlling a cooking appliance, which may help to find a failure of the cooling fan quickly and may be effectively applied to a cooking appliance in which a plurality of units is stacked on top of one another.

To achieve the above aims, in a cooking appliance according to one aspect, a temperature measuring unit may be disposed at a supporter configured to support a circuit board, a cool air passage may be formed between a casing and the circuit board, and the temperature measuring unit may measure a temperature in the cool air passage.

Based on results of the temperature measuring unit's measurement of temperatures, a failure of a cooling fan may be found quickly.

The cooking appliance according to the invention controls an operation of a heating unit using results of monitoring of an increase per unit time in temperature of the cool air passage formed between the casing and the circuit board. Here, an increase per unit time in temperature means an increase rate of temperatures measured by a temperature measuring unit.

Accordingly, a failure of the cooling fan may be found quickly and a cooking operation may stop immediately, thereby protecting electronic components from a failure caused by overheating.

Additionally, a method for controlling a cooking appliance according to another aspect, determination on whether the cooling fan stops operating may be made based on results of monitoring of an increase per unit time in temperature in the cool air passage, and when it is determined that the cooling fan stops operating, the heating unit may stop operating.

Accordingly, a control operation to stop the cooking appliance from operating at a time of failure of the cooling fan may be applied to various types of ovens having different sizes of cooking space and heat generating capacity.

With the above configuration, a failure of a cooling fan in all units of a cooking appliance in which a plurality of units is stacked on top of one another may be effectively found.

According to another aspect, when a difference between a current temperature value and a previous temperature value, measured predetermined time prior to measurement of the current temperature value, is equal to and greater than a predetermined difference, it may be determined that the cooling fan stops operating.

According to another aspect, when events, in which a difference between a current temperature value and a temperature value measured predetermined time prior to measurement of the current temperature value is equal to or greater than a predetermined difference, occur predetermined consecutive times, it may be determined that the cooling fan stops operating.

A cooking appliance according to the invention, including a casing provided with a cooking space therein, a heating unit configured to heat the cooking space, and an electronic component space provided outside the casing, may include a circuit board disposed in the electronic component space; a supporter configured to space the circuit board from the casing and to support the circuit board; a cooling fan configured to generate a flow of cool air passing through a cool air passage that is surrounded by the casing, the circuit board and the supporter; a temperature measuring unit installed at the supporter and configured to measure temperatures in the cool air passage; and a controller configured to control an operation of the heating unit based on an increase per unit time in temperatures measured by the temperature measuring unit. Here, an increase per unit time in the temperatures means an increase rate of the temperatures.

The controller may stop the heating unit from operating when the increase per unit time in temperatures measured by the temperature measuring unit exceeds a predetermined value.

The temperature measuring unit may be disposed between the casing and the circuit board.

The electronic component space is disposed upon the casing. The supporter comprises an air guide disposed laterally adjacent to the circuit board, protruding from the casing upward, and blocking a lateral side of the cool air passage. The temperature measuring unit may be installed at the air guide.

The electronic component space may be disposed in the upper portion of the casing. A door may be disposed at a front of the casing to cover the cooling space. The cooling fan may be disposed rearward from the door. The temperature measuring unit may be disposed between the door and the cooling fan.

The temperature measuring unit may be disposed closer to the door than to the cooling fan.

A method for controlling the cooking appliance according to another aspect may include a monitoring step of monitoring an increase per unit time in temperatures in the cool air passage; a determining step of determining whether the cooling fan stops operating or not based on the monitored increase per unit time, i.e. based on results monitored in the monitoring step; and an operation controlling step of stopping the heating unit from operating when it is determined that the cooling fan stops operating.

The monitoring step may include a temperature measuring step of measuring temperatures in the cool air passage at a first predetermined time interval, and a comparing step of comparing a current value of one of the temperatures that are currently measured in the temperature measuring step with a previous value of one of the temperatures that were measured a second predetermined time before the current value is measured in the temperature measuring step. A time span of the second predetermined time may be greater than the first predetermined time interval.

The determining step may include determining that the cooling fan stops operating when a difference between the two measured values compared in the comparing step is equal to or greater than a predetermined difference.

The comparing step may be repeated at a third predetermined time interval which is less than the time span of the second predetermined time. The determining step may include determining that the cooling fan stopped operating when events, in which the difference between the two measured values compared in the comparing step is equal to or greater than the predetermined difference, occur predetermined consecutive times or greater.

The predetermined difference may be three to five °C. The time span of the second predetermined time may be five to seven minutes. The third predetermined time interval may be <NUM> to <NUM> seconds. The predetermined consecutive times may be two to four times.

The comparing step may start after a time point when a temperature measured in the temperature measuring step equal to or greater than a predetermined comparison initiation temperature.

Additionally, the comparing step may start after the second predetermined time passes from the time point when a temperature measured in the temperature measuring step reaches the predetermined comparison initiation temperature or greater.

The cooking appliance may include a first unit disposed in an upper portion of the cooking appliance and a second unit disposed at a position lower than the first unit, the first unit and the second unit may respectively include the casing, the heating unit and the cooling fan, the temperature measuring unit may be disposed in the first unit, and the operation controlling step may include stopping the heating unit from operating when at least any one of the cooling fan of the first unit and the cooling fan of the second unit stops operating.

When the first unit operates, the comparing step may start from a time point when a temperature measured in the temperature measuring step reaches a first predetermined comparison initiation temperature or greater, and when the second unit operates, the comparing step may start from a time point when a temperature measured in the temperature measuring step reaches a second predetermined comparison initiation temperature or greater. The second predetermined comparison initiation temperature may be lower than the first predetermined comparison initiation temperature.

Using a cooking appliance and a method for controlling the same according to the present disclosure, a failure of a cooling fan may be quickly determined based on results of a temperature measuring unit's measurement of temperatures.

Additionally, when electronic components do not cool properly due to a failure of the cooling fan, the failure of the cooling fan may be quickly determined and a cooking operation may stop immediately, thereby protecting the electronic components from a failure caused by overeating.

Further, when the cooling fan fails, this control operation of stopping the operation of the cooking appliance at a time point of failure of the cooling fan may be applied to various types of ovens having different sizes of cooking space and heat generating capacity.

Furthermore, a failure of at least one cooling fan in a cooking appliance having a plurality of units stacked on top of one another may be effectively determined, and accordingly, electronic components may be protected from a failure caused by overheating.

Below, preferred embodiments according to the disclosure are specifically described with reference to the accompanying drawings. In the drawings, identical reference numerals can denote identical or similar components.

When one component is described as being "in an upper portion (or a lower portion)" of another component, or "on (or under)" another component, one component can be placed on the upper surface (or under the lower surface) of another component, and an additional component may be interposed between another component and one component on (or under) another component.

When one component is described as being "connected", "coupled", or "connected" to another component, one component can be directly connected, coupled or connected to another component. However, it is also to be understood that an additional component can be "interposed" between the two components, or the two components can be "connected", "coupled", or "connected" through an additional component.

The singular forms "a", "an" and "the" are intended to include the plural forms as well, unless explicitly indicated otherwise. It should be further understood that the terms "comprise" or "have" and the like, set forth herein, are not interpreted as necessarily including all the stated components or steps but can be interpreted as excluding some of the stated components or steps or can be interpreted as including additional components or steps.

<FIG> is a front perspective view showing a cooking appliance according to the invention, and <FIG> is a front perspective view showing a portion separated from the cooking appliance in <FIG>. <FIG> is a rear perspective view showing the cooking appliance in <FIG>, and <FIG> is a front perspective view showing the cooking appliance in <FIG> without a door.

Referring to <FIG>, the cooking appliance may include a first unit <NUM> in an upper portion of the cooking appliance, and a second unit <NUM> in a lower portion of the cooking appliance.

The first unit <NUM> and the second unit <NUM> may all be a sealed type cooking appliance such as an electric oven and the like, but not limited.

For example, the cooking appliance may include an electric oven as the first unit <NUM> in the upper portion thereof, and a gas oven as the second unit <NUM> in the lower portion thereof. On the contrary, the cooking appliance may include a gas oven as the first unit <NUM> in the upper portion thereof, and an electric oven as the second unit <NUM> in the lower portion thereof.

In another example, instead of an oven, another sort of sealed type cooking appliance such as a microwave oven may be used as the first unit <NUM> or the second unit <NUM>, or an open type cooking appliance such as a cooktop, a hob, a griddle and the like may be used as the first unit <NUM> and disposed onto the second unit <NUM>.

Hereunder, a configuration of a cooking appliance including electric ovens as the first unit <NUM> and the second unit <NUM> is described as an example. In the description, a configuration of the first unit <NUM> is mainly described.

Referring to <FIG>, a main body <NUM> may form an exterior of the first unit <NUM>. The main body <NUM> may have a shape including an approximate cuboid shape, and may be made of a material having predetermined strength to protect various components installed in an inner space thereof.

The main body <NUM> may include a casing <NUM> forming a skeleton of the main body <NUM>, and a front panel <NUM> disposed at a front of the casing <NUM> and forming a front surface of the main body <NUM>. The casing <NUM> may have a cooking space <NUM> therein, and an opening configured to open the cooking space <NUM> forward may be formed inside the front panel <NUM>.

The main body <NUM> has the cooking space <NUM> therein. The cooking space <NUM> may have a hexahedron shape a front surface of which is open. With the cooking space <NUM> closed, an inner space of the cooking space <NUM> may be heated to cook food. That is, in the cooking appliance, the inner space of the cooking space <NUM> may be a space where food is actually cooked.

The cooking appliance is provided with a heating unit configured to heat the cooking space <NUM>. As an example not according to the invention, a convection unit <NUM> may be provided as the heating unit on a rear side of the cooking space <NUM>. The convection unit <NUM> may heat the inner space of the cooking space <NUM> as a result of convection of hot air. Additionally, an upper heater configured to heat the inner space of the cooking space <NUM> from an upper side of the cooking space <NUM> is provided as the heating unit on the upper side of the cooking space <NUM>, and a lower heater configured to heat the inner space of the cooking space <NUM> from a lower side of the cooking space <NUM> may be provided as the heating unit on the lower side of the cooking space <NUM>.

The main body <NUM> may be provided with a door <NUM> configured to swivel and selectively open and close the cooking space <NUM>, at a front thereof. The door <NUM> may be a pull-down type door that opens and closes the cooking space <NUM> in a way that an upper end of the door <NUM> swivels with respect to a lower end of the door <NUM> in an up-down direction.

The door <NUM> may have a hexahedron shape having a predetermined thickness as a whole, and may have a handle <NUM> on a front surface thereof. A user may grip the handle <NUM> to swivel the door <NUM>.

A control panel <NUM> may be provided in an upper portion of a front surface of the cooking appliance, i.e., on a front surface of an upper portion of the casing <NUM>. The control panel <NUM> may form a portion of an exterior of the front surface of the cooking appliance. The control panel <NUM> may include a knob <NUM> for controlling an operation of the cooking appliance, a display <NUM> configured to display an operation state of the cooking appliance, and the like.

An electronic component space <NUM> is provided outside the casing <NUM>. The electronic component space <NUM> may be disposed in the upper portion of the casing <NUM> and behind the control panel <NUM>. In the electronic component space <NUM>, a space for installing electronic components may be formed.

A front surface of the electronic component space <NUM> may be shielded by the front panel <NUM>. The front panel <NUM> may be disposed between the casing <NUM> and the door <NUM>. The front panel <NUM> may be disposed in a way that at least a portion of the front panel <NUM> blocks a front of the electronic component space <NUM>. For example, an upper area of the front panel <NUM> disposed in an upper portion of the cooking space <NUM>, may shield the front surface of the electronic component space <NUM>.

The front panel <NUM> may have an inlet <NUM>. The inlet <NUM> may be formed on the front panel <NUM> in a way that penetrates in a front-rear direction. The inlet <NUM> may form a passage for introducing air outside the electronic component space <NUM> into the electronic component space <NUM> on the front panel <NUM>.

Upper, lateral and rear boundary surfaces of the electronic component space <NUM> may be defined by an electronic component space cover <NUM> covering the electronic component space <NUM> from above. Additionally, the lower boundary surface of the electronic component space <NUM> may be defined by an upper surface of the casing <NUM>.

<FIG> is a rear perspective view showing the cooking appliance in <FIG> without some components, and <FIG> is an enlarged rear perspective view showing a portion of "VI" in <FIG>. <FIG> is a side view showing the cooking appliance in <FIG>, and <FIG> is a view showing a flow of cool air in the cooking appliance of <FIG>.

In <FIG>, the electronic component space cover, a circuit board, a supporter and the like are omitted. In <FIG>, the electronic component space cover is omitted.

The upper surface of the casing <NUM> may include a first area 11a, and a second area <NUM>1b, as illustrated in <FIG>.

The first area 11a may correspond to a portion disposed approximately at a center of the upper surface of the casing <NUM>, and the second area 11b may correspond to a surrounding portion encircling the first area 11a. The first area 11a may be disposed further upward than the second area 11b, and a step may be formed between the first area 11a disposed upward and the second area 11b disposed downward.

As described above, various types of electronic components may be disposed in the electronic component space <NUM>. According to the invention, a circuit board <NUM> is disposed in the electronic component space <NUM>, as illustrated in <FIG>. The circuit board <NUM> may be provided with various types of elements, a circuit and the like in relation to receipt of an operation signal, generation of a control signal for controlling an operation of the heating unit and the like input through the control panel <NUM>.

The circuit board <NUM>, as illustrated in <FIG>, may be disposed in the upper portion of the casing <NUM> through a supporter <NUM>. The supporter <NUM> may support the circuit board <NUM> while spacing the circuit board <NUM> from the casing <NUM>. For example, the supporter <NUM> may be disposed in the upper portion of the casing <NUM>, and the circuit board <NUM> may be coupled to the supporter <NUM> at a position where the circuit board <NUM> is spaced upward from the casing <NUM>. Accordingly, the circuit board <NUM> may be spaced a predetermined distance apart from the casing <NUM>.

The supporter <NUM> may include a support plate <NUM>, an air guide <NUM>, and a rear plate <NUM>.

The support plate <NUM> may form a flat surface in parallel with the upper surface of the casing <NUM>. The support plate <NUM> may be spaced a predetermined distance from the upper surface of the casing <NUM>. An upper surface of the supporter <NUM> may be defined by the support plate <NUM>. That is, the support plate <NUM> may form the upper surface of the supporter <NUM>.

The circuit board <NUM> may be mounted onto an upper surface of the support plate <NUM>, for example. The circuit board <NUM> may be accommodated in a board case <NUM>, and the board case <NUM> may be coupled to the support plate <NUM> in a state of being mounted onto the upper surface of the support plate <NUM>.

The board case <NUM> may have a plurality of coupling projections <NUM>. Each of the coupling projections <NUM> may be provided in a way that protrudes to an outside of the board case <NUM> in a lateral direction thereof. In a state where each coupling projection <NUM>, provided as described above, and the support plate <NUM> contact each other in the up-down direction, the coupling projection <NUM> and the support plate <NUM> may be coupled using a screw. Accordingly, the board case <NUM> and the support plate <NUM> may be coupled.

That is, the board case <NUM> may be fixed onto the upper surface of the support plate <NUM>, and the circuit board <NUM> may be accommodated in the board case <NUM>. Thus, the circuit board <NUM> may be fixed onto the upper surface of the support plate <NUM>.

The air guide <NUM> may be disposed in a lower portion of the support plate <NUM>, i.e., between the upper surface of the casing <NUM> and the support plate <NUM>. According to the invention, the air guide <NUM> may be disposed in a lateral portion of the circuit board <NUM>. The air guide <NUM> may be formed into a flat surface in parallel with a side 11c of the casing <NUM> and may form a side of the supporter <NUM>.

The support plate <NUM> may have a length greater than a length of the circuit board <NUM> in the front-rear direction. The air guide <NUM> may have a length corresponding to the front-rear length of the support plate <NUM>.

The air guide <NUM> may be coupled to the upper surface of the casing <NUM>, and the support plate <NUM>. To this end, the air guide <NUM> may have a lower end coupling surface 37a and an upper end coupling surface 37b, respectively at a lower end and an upper end thereof.

The lower end coupling surface 37a may be disposed at the lower end of the air guide <NUM> and formed into a flat surface in parallel with the upper surface of the casing <NUM>. The upper end coupling surface 37b may be disposed at the upper end of the air guide <NUM> and formed into a flat surface in parallel with the support plate <NUM>. For example, the lower end coupling surface 37a and the upper end coupling surface 37b may be formed in a way that a portion of an upper side of the air guide <NUM> and a portion of a lower side of the air guide <NUM> are bent.

The lower end coupling surface 37a may be coupled to the upper surface of the casing <NUM> in contact with the upper surface of the casing <NUM>. The upper end coupling surface 37b may be coupled to the support plate <NUM> in contact with a lower surface or the upper surface of the support plate <NUM>. The lower end coupling surface 37a and the casing <NUM>, and the upper end coupling surface 37b and the support plate <NUM> may be screw-coupled.

For example, the casing <NUM>, the air guide <NUM>, and the support plate <NUM> may also be coupled, in a way that the coupling projection <NUM>, the support plate <NUM> and the upper end coupling surface 37b are coupled by a single screw at a time, in a state where the coupling projection <NUM>, the support plate <NUM> and the upper end coupling surface 37b overlap in the up-down direction.

As a result of coupling among the casing <NUM>, the air guide <NUM> and the support plate <NUM>, the support plate <NUM> may be spaced from the upper surface of the casing <NUM> by an approximate height of the air guide <NUM>. Accordingly, the circuit board <NUM> supported by the support plate <NUM> may also be spaced from the upper surface of the casing <NUM> by an approximate height of the air guide <NUM>.

Additionally, the support plate <NUM> may be coupled to the front panel <NUM> disposed at a front thereof. For example, a portion of an upper end of the front panel <NUM> may be bent to form a coupling surface in parallel with the support plate <NUM>, and a portion of the support plate <NUM> may protrude toward the front panel <NUM> to be coupled to the coupling surface of the front panel <NUM>.

Like the air guide <NUM>, the rear plate <NUM> may be disposed in the lower portion of the support plate <NUM>, i.e., between the upper surface of the casing <NUM> and the support plate <NUM>. Additionally, the air guide <NUM> may be disposed at a rear of the circuit board <NUM>. The rear plate <NUM> may be formed into a flat surface in parallel with a rear surface 11d of the casing <NUM> and may form a rear surface of the supporter <NUM>.

The rear plate <NUM> may be disposed between a cooling fan <NUM> described below and the circuit board <NUM>. The rear plate <NUM> may form a blocking wall that blocks between the cooling fan <NUM> and the circuit board <NUM>.

Unlike the air guide <NUM> mounted onto the first area 11a of the upper surface of the casing <NUM>, the rear plate <NUM> may be mounted onto the second area <NUM>1b of the upper surface of the casing <NUM>. That is, the rear plate <NUM> may be disposed further upward than the air guide <NUM> and may protrude further upward than the air guide <NUM> and the circuit board <NUM>. The rear plate <NUM> may be coupled to at least any one of the air guide <NUM> and the support plate <NUM> and fixed to the rear of the circuit board <NUM>.

A cool air passage <NUM> may be formed between the upper surface of the casing <NUM>, and the support plate <NUM> spaced apart from each other. The cool air passage <NUM> may form a space encircled (i.e. surrounded) by the upper surface of the casing <NUM>, the support plate <NUM> and the air guide <NUM>. A front of the cool air passage <NUM> may be blocked by the front panel <NUM>, and a rear of the cool air passage <NUM> may be blocked by the rear plate <NUM>.

That is, an upper surface of the cool air passage <NUM> may be defined by the support plate <NUM>, and a side of the cool air passage <NUM> may be defined by the air guide <NUM>, and a front surface and a rear surface of the cool air passage <NUM> may be respectively defined by the front panel <NUM> and the rear plate <NUM>.

The cool air passage <NUM>, as illustrated in <FIG> and <FIG>, may connect to the inlet <NUM> formed on the front panel <NUM>. That is, the inlet <NUM> may form a passage for introducing air outside the cooking appliance into the cool air passage <NUM> on the front panel <NUM>, as illustrated in <FIG>.

Further, an outlet <NUM> may be formed on the rear plate <NUM> in a way that penetrates in the front-rear direction. The cool air passage may connect to the outlet <NUM>, and the outlet <NUM> may form a passage for allowing air in the cool air passage <NUM> to pass through the rear plate <NUM> on the rear plate <NUM>.

The cooling fan <NUM> may be disposed near the rear surface of the casing <NUM> while disposed in the electronic component space <NUM>. The cooling fan <NUM> may include a turbo fan disposed on the upper surface of the casing <NUM>. The cooling fan <NUM> may suction air at a front of the electronic component space <NUM> and discharge the air to a space at the rear of the cooking space <NUM>.

Additionally, a lower through hole, communicating with the space at the rear of the cooking space <NUM> and being open forward, may be provided in a lower portion of the front of the main body <NUM>.

When the cooling fan <NUM> operates, external air in the lower portion of the front of the main body <NUM> may be introduced into the door <NUM> through an air flow hole provided in a lower portion of the door <NUM> and then may rise, as illustrated in <FIG>. In this process, the door <NUM>, heated by air delivered from the cooking space <NUM> to the door <NUM>, may cool.

The air rising in the door <NUM> may be introduced into the electronic component space <NUM> through an air flow hole provided in an upper portion of the door <NUM> and through the inlet <NUM> formed on the front panel <NUM> in a penetrating manner. The air introduced into the electronic component space <NUM> may be suctioned to the cooling fan <NUM>, may cool electronic components in the electronic component space <NUM>, may be discharged to the space at the rear of the cooking space <NUM>, and then may be discharged to the front of the main body <NUM>.

The air introduced into the electronic component space <NUM> through the inlet <NUM>, i.e., most of the cool air, may pass through the cool air passage <NUM>. The flow of the cool air may be guided by the air guide <NUM> disposed on the side of the cool air passage <NUM>.

The cool air introduced into the cool air passage <NUM> may cool the electronic components such as the circuit board <NUM> supported by the supporter <NUM>, may escape from the cool air passage <NUM> through the outlet <NUM> and may be suctioned into the cooling fan <NUM>.

Referring to <FIG>, a space between the cool air passage <NUM> and the cooling fan <NUM> may be blocked by the rear plate <NUM>, and a passage between the cool air passage <NUM> and the cooling fan <NUM> may be formed only by the outlet <NUM>. Accordingly, cool air introduced into the cool air passage <NUM> may cool the circuit board <NUM> and the like while staying in the cool air passage <NUM> for a short period of time instead of immediately escaping from the cool air passage <NUM>, and then may be discharged out of the cool air passage <NUM> through the outlet <NUM>.

Thus, a temperature of the air introduced into the cool air passage <NUM> may be similar to a temperature of the air heat-exchanged with the circuit board <NUM> and the like, e.g., a temperature of the circuit board <NUM>, rather than a temperature of the cool air before the introduction of the cool air into the inlet <NUM>.

The cooking appliance further includes a temperature measuring unit100. The temperature measuring unit <NUM> may be provided to measure temperatures of the electronic components disposed in the electronic component space <NUM>. The temperature measuring unit <NUM> may be provided to measure a temperature of the circuit board <NUM>, for example.

The temperature measuring unit <NUM> is installed at the supporter <NUM> and supported by the supporter <NUM>. The temperature measuring unit <NUM> measures a temperature in the cool air passage <NUM> to indirectly measure the temperature of the circuit board <NUM>. The temperature measuring unit <NUM> may measure the temperature of the circuit board <NUM> as described above, and measurements of the temperature measuring unit <NUM> may be used as data for determining whether the cooling fan <NUM> operates.

The temperature measuring unit <NUM> may include a thermistor installed at the supporter <NUM> and configured to measure a temperature in the cool air passage <NUM>, for example.

The temperature measuring unit <NUM> may be disposed between the upper surface of the casing <NUM>, and the circuit board <NUM>. An up-down position of the temperature measuring unit <NUM> may be between the upper surface of the casing <NUM>, and the circuit board <NUM>. Additionally, a front-rear position of the temperature measuring unit <NUM> may overlap a position of the circuit board <NUM>.

Specifically, the temperature measuring unit <NUM> is installed at the air guide <NUM>. The air guide <NUM> may be a component between the upper surface of the casing <NUM>, and the circuit board <NUM>. Further, the air guide <NUM> may be a component disposed in lateral portions of the circuit board <NUM> and the cool air passage <NUM>.

Since the temperature measuring unit <NUM> is installed at the air guide <NUM>, the temperature measuring unit <NUM> may be disposed between the upper surface of the casing <NUM>, and the circuit board <NUM>. Additionally, since at least a portion of the temperature measuring unit <NUM> protrudes toward the cool air passage <NUM>, the temperature measuring unit <NUM> may be disposed at a position that overlaps the position of the circuit board <NUM>, and at least a portion of the temperature measuring unit <NUM> may be disposed in the cool air passage <NUM>.

The disposition of the temperature measuring unit <NUM> between the upper surface of the casing <NUM> and the circuit board <NUM>, and the disposition of the temperature measuring unit <NUM> in the cool air passage <NUM> may produce the following effects.

During cooking in the coking space <NUM>, a temperature in the cooking space <NUM> may rise due to heat generated by the heating unit. Additionally, a temperature of the casing <NUM> encircling an outside of the cooking space <NUM> may also rise. That is, during cooking in the cooking space <NUM>, the temperature of the casing <NUM> may remain high.

Accordingly, when the temperature measuring unit <NUM> is disposed in contact with the casing <NUM> or disposed at a position very close to the casing <NUM>, the temperature of the casing <NUM> may significantly affect results of the temperature measuring unit <NUM>'s measurement of temperatures. That is, a temperature measured by the temperature measuring unit <NUM> may be almost similar to the temperature of the casing <NUM>.

Thus, since the results of the temperature measuring unit <NUM>'s measurement are greatly affected by the temperature of the casing <NUM> regardless of whether cool air is passing through the cool air passage <NUM>, it is difficult to determine whether the cooling fan <NUM> operates, based on the results of the temperature measuring unit <NUM>'s measurement.

When the cooking appliance described above operates, the circuit board <NUM> may generate heat during its operation. Accordingly, a temperature of the circuit board <NUM> may rise. Additionally, since heat generated through the casing <NUM> affects the temperature of the circuit board <NUM>, the temperature of the circuit board <NUM> may rise while the cooking appliance operates.

Accordingly, when the temperature measuring unit <NUM> is disposed in contact with the circuit board <NUM> or disposed at a position very close to the circuit board <NUM>, the temperature of the circuit board <NUM> may significantly affect the results of the temperature measuring unit <NUM>'s measurement of temperatures. That is, a temperature measured by the temperature measuring unit <NUM> may be almost similar to the temperature of the circuit board <NUM>.

Thus, since the results of the temperature measuring unit <NUM>'s measurement are greatly affected by the temperature of the circuit board <NUM> regardless of whether cool air is passing through the cool air passage <NUM>, it is difficult to determine whether the cooling fan <NUM> operates, based on the results of the temperature measuring unit <NUM>'s measurement.

Considering this, the temperature measuring unit <NUM> may be disposed between the upper surface of the casing <NUM>, and the circuit board <NUM>, and may be somewhat spaced apart from the casing <NUM> and the circuit board <NUM>.

In an example, the temperature measuring unit <NUM> may be spaced the same distance respectively apart from the upper surface of the casing <NUM> and the circuit board <NUM>. In another example, considering the temperature of the casing <NUM> higher than that of the circuit board <NUM>, the temperature measuring unit <NUM> may be disposed at a position a little closer to the circuit board <NUM> than to the upper surface of the casing <NUM>. In this case, certainly, the temperature measuring unit <NUM> may not be disposed in contact with the circuit board <NUM> or may not be disposed at a position too close to the circuit board <NUM>.

The front-rear position of the temperature measuring unit <NUM> may be between the door <NUM> and the cooling fan <NUM>, and may be disposed closer to the door <NUM> than to the cooling fan <NUM>.

The cooling fan <NUM> may be disposed in the electronic component space <NUM>, and disposed eccentrically to a rear of the electronic component space <NUM>. That is, the cooling fan <NUM> may be disposed near the rear surface of the casing <NUM>.

The circuit board <NUM> may be disposed eccentrically to the front of the electronic component space <NUM>. That is, the circuit board <NUM> may be disposed near the control panel <NUM>. Since the control panel <NUM> is disposed at the front of the electronic component space <NUM>, the circuit board <NUM> needs to be disposed eccentrically to the front of the electronic component space <NUM> to simplify a wire connection between the control panel <NUM> and the circuit board <NUM> and make the wire connection more efficient.

When the circuit board <NUM> is disposed eccentrically to the front of the electronic component space <NUM> as described above, i.e., when the circuit board <NUM> is disposed closer to the door <NUM> than to the cooling fan <NUM>, the temperature measuring unit <NUM> needs to be disposed closer to the door <NUM> than to the cooling fan <NUM>. When the temperature measuring unit <NUM> is disposed closer to the door <NUM> than to the cooling fan <NUM>, the temperature measuring unit <NUM> may effectively measure the temperature in the cool air passage <NUM> and may be designed to be fixed to the supporter <NUM>.

As the temperature measuring unit <NUM> becomes closer to the cooling fan <NUM>, the temperature measuring unit <NUM> may be more affected by the cooling fan <NUM> than by the circuit board <NUM>. That is, the results of the temperature measuring unit <NUM>'s measurement may be more affected by whether the cooling fan <NUM> operates than by a temperature of the circuit board <NUM>.

Additionally, when the temperature measuring unit <NUM> is disposed near the cooling fan <NUM>, it is difficult to install the temperature measuring unit <NUM> at the supporter <NUM>. For the temperature measuring unit <NUM> to be disposed near the cooling fan <NUM>, the front-rear length of the supporter <NUM> may excessively increase or an additional structure for fixing the temperature measuring unit <NUM> needs to be added.

Considering this, the temperature measuring unit <NUM> is installed at the supporter <NUM>, specifically, the air guide <NUM>, and may be disposed closer to the door <NUM> than to the cooling fan <NUM> such that at least a portion of the temperature measuring unit <NUM> is disposed in the cool air passage <NUM>.

However, it is undesirable to dispose the temperature measuring unit <NUM> too close to the door <NUM>. While the door <NUM> is opened and closed, hot air in the cooking space <NUM> may be introduced into the electronic component space <NUM> through the inlet <NUM> (see FIG. <NUM>), and the hot air introduced may be a cause for distortion of the results of the temperature measuring unit <NUM>'s measurement.

Accordingly, while the temperature measuring unit <NUM> is disposed between the inlet <NUM> and the cooling fan <NUM>, the temperature measuring unit <NUM> may be spaced from the inlet <NUM> rearward by a predetermined distance.

The predetermined distance may be determined considering a scope affected by the hot air in the cooking space <NUM>, which is introduced into the electronic component space through the inlet <NUM> during the opening and closing of the door <NUM>.

For example, suppose that in the electronic component space <NUM>, an area in a range of <NUM> from the inlet <NUM> in a rearward direction thereof undergoes a rapid increase in its temperature when the door <NUM> is opened and then closed. Then the predetermined distance may be set to <NUM>.

The predetermined distance may be a distance (hereinafter, "circuit board spaced distance") or greater between the circuit board <NUM> and the upper surface of the casing <NUM> that are spaced from each other. For example, if the circuit board spaced distance is <NUM>, the predetermined distance may be set to <NUM> or greater.

This means that the temperature measuring unit <NUM> needs to be spaced from the inlet <NUM> and that the temperature measuring unit <NUM> needs to be spaced from the inlet <NUM> by at least the circuit board spaced distance.

Ordinarily, the circuit board <NUM> may be spaced from the casing <NUM> to such an extent that heat of the casing <NUM> does not directly affect the circuit board <NUM>. Considering this, it may be assumed that an area spaced from the inlet <NUM> rearward by the circuit board spaced distance or greater is not directly affected by hot air that is introduced when the door <NUM> is opened and then closed.

Accordingly, the temperature measuring unit <NUM> may be spaced from the inlet <NUM> by the circuit board spaced distance or greater. Thus, the results of the temperature measuring unit <NUM>'s measurement may not be affected by the hot air that is introduced when the door <NUM> is opened and then closed.

In another example, a scope affected by hot air in the cooking space <NUM>, which is introduced into the electronic component space through the inlet <NUM> during the opening and closing of the door <NUM>, may be actually measured, and based on results of the measurement, the predetermined distance may also be determined.

[Configuration regarding function of detecting failure of cooling fan].

<FIG> is a block diagram schematically showing a configuration of the cooking appliance.

The cooking appliance includes a controller <NUM>, as illustrated in <FIG>. The controller <NUM> may control a cooking operation of the cooking appliance. For example, the controller <NUM> may control operations of the heating unit and the cooling fan <NUM> based on an operation signal input through the knob <NUM> and the like of the control panel <NUM>.

The controller <NUM> may also control an operation of the display <NUM> configured to display an operation state of the cooking appliance. In an example, the controller <NUM> may include a micro controller mounted onto the circuit board <NUM>.

Additionally, the controller <NUM> may stop a cooking operation of the cooking appliance when an increase per unit time in temperatures measured by the temperature measuring unit <NUM> exceeds a predetermined range. Description in relation to this is provided hereunder.

Ordinarily, while the cooking appliance performs a cooking operation, the heating unit H operates, and then temperatures of the casing <NUM> and the circuit board <NUM> may gradually increase. The temperature of the circuit board <NUM> may increase due to heat generated as a result of operation of the circuit board <NUM> or due to the effect of heat of the casing <NUM> on the circuit board <NUM>.

While the heating unit H operates as described above, the cooling fan <NUM> may also operate. When the cooling fan <NUM> operates, external air in the lower portion of the front of the main body <NUM> may be introduced through a lower portion of the door <NUM> and then may be discharged through an upper portion of the door <NUM> while cooling the door <NUM>, and the air discharged through the upper portion of the door <NUM> may be introduced into the cool air passage <NUM> through the inlet <NUM> that is formed on the front panel <NUM> in a penetrating manner.

The cool air introduced into the cool air passage <NUM> may cool the electronic components such as the circuit board <NUM> supported by the supporter <NUM> and the like, may escape from the cool air passage <NUM> through the outlet <NUM>, may be suctioned into the cooling fan <NUM>, may be discharged to the space at the rear of the cooking space <NUM> and then may be discharged to the front of the main body <NUM>.

The space between the cool air passage <NUM> and the cooling fan <NUM> may be blocked by the rear plate <NUM>, and a passage between the cool air passage <NUM> and the cooling fan <NUM> may be formed only by the outlet <NUM>. Accordingly, the cool air introduced into the cool air passage <NUM> may cool the circuit board <NUM> and the like while staying in the cool air passage <NUM> for a short period of time instead of immediately escaping from the cool air passage <NUM>, and then may be discharged out of the cool air passage <NUM> through the outlet <NUM>.

The cooling fan <NUM> and the heating unit H may be disposed in both the first unit <NUM> and the second unit <NUM>. The temperature measuring unit <NUM> may be disposed in at least any one of the first unit <NUM> and the second unit <NUM>. The temperature measuring unit <NUM> is disposed in the first unit <NUM>, for example.

<FIG> is a flow chart schematically showing a process of controlling the cooking appliance, and <FIG> is a flow chart showing processes of detecting a failure of a cooling fan and controlling an operation of a heating unit in the cooking appliance. <FIG> is a flow chart specifically showing a process of detecting a failure of a cooling fan of the cooking appliance, and <FIG> is a graph showing a tendency in a change in temperatures of an electronic component space of the cooking appliance.

Logic of detecting a failure of the cooling fan of the cooking appliance is described hereunder with reference to <FIG>.

Referring to <FIG>, when the cooking appliance operates in a first setting mode, the heating unit H operates. Accordingly, the temperature measuring unit <NUM> may also operate. The first setting mode may involve various cooking operations or a self-cleaning operation of the cooking appliance. Hereunder, the logic of detection a failure of the cooling fan of the cooking appliance is described during the self-cleaning operation of the cooking appliance.

The self-cleaning function of the cooking appliance may involve automatically removing contaminants such as a greasy substance and the like attached (adhering) to a wall of the cooking space. When contaminants such as a greasy substance and the like are attached to a wall of the cooking space, the cooking appliance may perform the self-cleaning function using pyrolysis that is thermal decomposition in which a heat source such as the heating unit H heats the inside of the cooking space to maintain a temperature in the cooking space at a high level for a long period of time and burns out the contaminants.

During the self-cleaning process, the temperature in the cooking space may be maintained at a high level, and accordingly, a temperature of the electronic component space <NUM> may rise. When the cooling fan <NUM> makes operational errors during the self-cleaning process, the temperature of the electronic component space <NUM> may excessively rise, and temperatures of the electronic components in the electronic component space <NUM> may excessively rise.

During the self-cleaning process, the cooking appliance may monitor the temperature in the electronic component space <NUM>. The temperature monitoring of the cooking appliance may involve monitoring an increase per unit time in temperatures in the cool air passage <NUM> using the temperature measuring unit <NUM> and the controller <NUM> (S10). The above step (hereinafter, a "monitoring step (S <NUM>)") may be carried out as follows.

As illustrated in <FIG>, while the self-cleaning function is performed, the temperature measuring unit <NUM> may measure temperatures in the cool air passage <NUM> at a first predetermined time interval (S110; hereinafter, a" temperature measuring step"). It would be better that the first predetermined time interval is short. For example, the first predetermined time interval may be set to less than one second.

Information on the temperatures in the cool air passage <NUM>, obtained by the temperature measuring unit <NUM>, may be transmitted to the controller <NUM> at the first predetermined time interval. The controller <NUM> having received the information on the temperature in the cool air passage <NUM>, obtained by the temperature measuring unit <NUM>, may compare a current value Tc, i.e., a current temperature value in the cool air passage <NUM> with a predetermined comparison initiation temperature T1, T2 and may determine whether the current value Tc is the predetermined comparison initiation temperature T1, T2 or greater.

The predetermined comparison initiation temperature T1, T2 may be set to a temperature of the electronic component space 30a, 30b, which is ordinarily measured during the cooking operation or the self-cleaning operation of the cooing appliance. In this case, the predetermined comparison initiation temperature T1, T2 may be set under the assumption that the cooling fan <NUM> operates normally. That is, the predetermined comparison initiation temperature T1, T2 may be set to an ordinary temperature of the electronic component space when the cooling fan <NUM> operates normally during the cooking operation or the self-cleaning operation of the cooking appliance.

The predetermined comparison initiation temperature T1, T2 may be set to a temperature that can be ordinarily measured in the cool air passage <NUM> on condition that the cooling fan <NUM> operates normally during the self-cleaning operation, for example.

A predetermined comparison initiation temperature T1 during the self-cleaning operation in the first unit <NUM>, and a predetermined comparison initiation temperature T2 during the self-cleaning operation in the second unit <NUM> may be set to a different value.

When the temperature measuring unit <NUM> is installed only in the first unit <NUM>, the temperature measuring unit <NUM> may directly measure a temperature of a corresponding area in an electronic component space 30a (hereinafter, a "first electronic component space") of the first unit <NUM>. Accordingly, there is no big difference between an actual temperature of the first electronic component space 30a and a temperature measured by the temperature measuring unit <NUM>.

However, it is difficult for the temperature measuring unit <NUM>, installed as described above, to directly measure a temperature of an electronic component space 30b (hereinafter, a "second electronic component space") of the second unit <NUM> in the second electronic component space 30b. Accordingly, the temperature measuring unit <NUM> has no option but to indirectly measure a temperature of the second electronic component space 30b. For example, the temperature measuring unit <NUM> may indirectly measure a temperature of the second electronic component pace 30b in a way that measures a temperature of air having passed through the second electronic component space 30b and then introduced into the first electronic component space 30a.

In this case, the temperature of the second electronic component space 30b indirectly measured by the temperature measuring unit <NUM> is certainly less than an actual temperature of the second electronic component space 30b. While air in the second electronic component space 30b moves to the first electronic component space 30a, heat loss may occur, and accordingly, when the air in the second electronic component space 30b arrives at the cool air passage <NUM>, a temperature of the air becomes less than a temperature of the air in the second electronic component space 30b.

Accordingly, when the predetermined comparison initiation temperature T1 during the self-cleaning operation in the first unit <NUM>, and the predetermined comparison initiation temperature T2 during the self-cleaning operation in the second unit <NUM> are set to the same value, the controller <NUM> may make a wrong determination about a state of the second electronic component space 30b.

That is, when a temperature of the second electronic component space 30b, indirectly measured by the temperature measuring unit <NUM>, is less than the predetermined comparison initiation temperature T1 although the temperature of the second electronic component space 30b is the predetermined comparison initiation temperature T1 or greater during the self-cleaning operation in the second unit <NUM>, the controller <NUM> may find that it does not need to determine whether the cooling fan <NUM> stops operating yet.

The predetermined comparison initiation temperature T1 (hereinafter, a "first predetermined comparison initiation temperature") during the self-cleaning operation of the first unit <NUM> may be <NUM> to <NUM>, and the predetermined comparison initiation temperature T2 (hereinafter, a "second predetermined comparison initiation temperature") during the self-cleaning operation of the second unit <NUM> may be <NUM> to <NUM>, for example. In this case, the predetermined comparison initiation temperature T1 of <NUM> to <NUM> during the self-cleaning operation of the first unit <NUM> is determined considering an actual temperature of <NUM> to <NUM> in the second electronic component space 30b at <NUM> to <NUM> measured by the temperature measuring unit <NUM> during the self-cleaning operation of the second unit <NUM>.

However, the figures may not be limited. The first predetermined comparison initiation temperature T1 may be properly set considering a temperature of the first electronic component space 30a, which is ordinarily measured during the self-cleaning operation in the first unit <NUM>, a range of temperatures at which various electronic components in the first electronic component space 30a can operate normally, and the like. Additionally, the second predetermined comparison initiation temperature T2 may be properly set considering a range of temperatures at which various electronic components in the second electronic component space 30b can operate normally, a temperature of the first electronic component space 30a, which is ordinarily measured during the self-cleaning operation in the second unit <NUM>, and the like.

When determining that the current value Tc is equal to or greater than the predetermined comparison initiation temperature in the above process, the controller <NUM> may compare the current value Tc with a previously value Ta that was measured a second predetermined time before the current value is measured (S13; hereinafter, a "comparing step"). A time span corresponding to the second predetermined time may be set to greater than the first predetermined time interval. For example, when the first predetermined time interval is less than one second, the time span of the second predetermined time may be set to one minute or greater.

The time span of the second predetermined time may be five to seven minutes, preferably, six minutes, for example. A specific time span of the second predetermined time is determined considering the following factors.

The first factor may be a time taken for a change in temperatures of the second electronic component space 30b during the self-cleaning operation in the second unit <NUM> to affect the temperature measuring unit <NUM> disposed in the first electronic component space 30a.

During the self-cleaning operation of the second unit <NUM>, a temperature of the second electronic component space 30b indirectly measured by the temperature measuring unit <NUM> may be less than an actual temperature of the second electronic component space 30b, and there is a difference between a time point when a change in the temperatures in the second electronic component space 30b occurs and a time point when the temperature measuring unit <NUM> detects the change. Additionally, it takes a certain amount of time for air in the second electronic component space 30b to move to the first electronic component space 30a, and it takes a certain amount of time for the air to raise a temperature of the first electronic component space 30a.

The second factor is a time taken for a temperature of the first electronic component space 30a or the second electronic component space 30b to rise up to a "dangerous" temperature when the cooling fan <NUM> is out of order, and/or a time for which the electronic components can continue to operate normally or does not fail even though the temperature of the first electronic component space 30a or the second electronic component space 30b has risen up to the dangerous temperature.

For example, when the dangerous temperature seriously affecting performance and durability of the electronic components is <NUM>, the second predetermined time needs to be set to less than a time period taken for the temperature of the first electronic component space 30a or the second electronic component space 30b to rise to <NUM>.

It is preferable to set the second predetermined time to less than a time period required to suppress an increase in the temperature of the first electronic component space 30a or the second electronic component space 30b before the temperature of the first electronic component space 30a or the second electronic component space 30b rises to <NUM>.

Additionally, the second predetermined time needs to be set to less than a time period for which the electronic components can operate normally or does not fail while the temperature of the first electronic component space 30a or the second electronic component space 30b rises to the dangerous temperature.

The two factors described above being taken into account, the second predetermined time may be set to five to seven minutes, preferably, six minutes but not limited. The second predetermined time may be set differently depending on a size and a material of the casing, capacity and performance of the heat source, performance of the cooling fan and the like.

The comparing step (S13) may be repeated at the third predetermined time interval. It is noteworthy that the comparing step (S13) is carried out on condition that a temperature measured in the temperature measuring step (S11) is the predetermined comparison initiation temperature or greater.

That is, when the condition that a temperature measured in the temperature measuring step (S11) is the predetermined comparison initiation temperature or greater is satisfied, the current temperature value Tc may be compared with the previous temperature value Ta that was measured the second predetermined time before the current temperature value Tc is measured.

If the current temperature value Tc is lower than the predetermined comparison initiation temperature while the comparing step (S13) is repeated, the comparing step (S13) proceeding may stop.

The third predetermined time interval may be set to greater than the first predetermined time interval and less than the time span of the second predetermined time. For example, when the first predetermined time interval is less than one second and the time span of the second predetermined time is set to six minutes, the third predetermined time interval may be set to one second or greater and less than six minutes.

The third predetermined time interval is <NUM> to <NUM> seconds, preferably, <NUM> seconds, for example. The figures were determined for allowing the comparing step (S13) to be repeated about two times to four times within one minute or so. Description in relation to this is provided below.

For example, the comparing step (S13) may start after the second predetermined time passes from a time point when a temperature measured in the temperature measuring step (S11) is the predetermined comparison initiation temperature or greater under a desirable condition that both the two measured values compared in the comparing step (S13) are the predetermined comparison initiation temperature or greater.

The temperature of the electronic component space 30a,30b may increase due to heat generated by the heating unit H while the cooking appliance continues to perform the cooking operation or the self-cleaning operation. Ordinarily, the temperature of the electronic component space 30a, 30b quickly increases until a time point when the temperature of the electronic component space 30a, 30b reaches the predetermined comparison initiation temperature T1, T2 and then increases very smoothly after the time point, and after a certain time point, remains constant.

Given that an ordinary temperature of the electronic component space 30a, 30b during the cooking operation or the self-cleaning operation of the cooking appliance is set to the predetermined comparison initiation temperature, there is no big change in the temperature of the electronic component space 30a,30b after the time point when the temperature of the electronic component space 30a, 30b reaches the predetermined comparison initiation temperature.

When the previous temperature value Ta of the two measured values compared in the comparing step (S13) is the predetermined comparison initiation temperature or less, it is high likely that there is a big difference between the two measured values compared in the comparing step (S13). The difference is likely caused not by a question of whether the cooling fan <NUM> stops operating but by a difference between a gradient of an increase in temperature at the time point when a current value Tc is measured and a gradient of an increase in temperature at the time point when a previous value Ta is measured.

Considering this, to improve accuracy of determining whether the cooling fan <NUM> stops operating using the difference between the current value Tc and the previous value Ta, both the two measured values compared in the comparing step (S13) may be the predetermined comparison initiation temperature or greater, for example.

While the monitoring step (S10) including the comparing step (S13) is repeated, the controller <NUM> may determine whether the cooling fan <NUM> stops operating based on results monitored in the monitoring step (S10) (S20; hereinafter, a "determining step").

The determining step (S20) may involve determining that the cooling fan <NUM> stops operating when the difference between the two measured values, i.e., the current value Tc and the previous value Ta, compared in the comparing step (S13) is a predetermined difference Ts or greater (S21).

Specifically, when the difference between the two measured values compared in the comparing step (S <NUM>) is the predetermined difference Ts or greater predetermined consecutive times or greater, the controller <NUM> may determine that the cooling fan <NUM> stops operating (S23). The predetermined difference Ts may be <NUM> to <NUM>, and the predetermined times may be two to four times, for example.

As described above, when the cooling fan <NUM> operates normally, it is unlikely that there is a big change in the temperatures of the electronic component space 30a,30b after the time point when the temperature of the electronic component space 30a, 30b reaches the predetermined comparison initiation temperature. That is, in a state in which the cooling fan <NUM> operates normally, a change in the temperatures of the electronic component space 30a, 30b is ordinarily less than <NUM> for a time period of the second predetermined time.

Accordingly, when the change in the temperatures of the electronic component space 30a, 30b is noticeably greater than <NUM> for the time period of the second predetermined time, the electronic component space 30a, 30b is not considered to have cooled properly. Additionally, the electronic component space 30a, 30b may not properly cool due to a failure of the cooling fan <NUM>.

Considering this, the determining step (S20) may involve determining that the cooling fan <NUM> stops operating when the difference between the two measured values compared in the comparing step (S13) is equal to or greater than the predetermined difference Ts. Further, the predetermined difference Ts may be set to <NUM> to <NUM>, preferably, <NUM> given that the change in the temperatures of the electronic component space 30a, 30b is ordinarily less than <NUM> for the time period of the second predetermined time, i.e., <NUM> minutes.

When the predetermined difference Ts is set to less than <NUM>, the controller <NUM> is likely to make a wrong determination due to an error in measurement of the temperature measuring unit <NUM> together with an instant change in the operation of the heating unit H and the cooling fan <NUM>. When the predetermined difference Ts is set to greater than <NUM>, the controller is likely to belatedly determine that the cooling fan <NUM> stops operating or unlikely to properly determine that the cooling fan <NUM> stops operating.

Considering this, the predetermined difference Ts may be properly set to a value, corresponding to a lowest temperature, among values that are measured when the cooling fan <NUM> surely stops operating.

Additionally, when the difference between the two measured values compared in the comparing step (S13) is the predetermined difference Ts or greater (hereinafter, a high-temperature detection state") predetermined consecutive times, i.e., two to four consecutive times, or greater, it may be determined that the cooling fan <NUM> stops operating.

Although the predetermined difference Ts is set to a value that is measured when the cooling fan <NUM> surely stops operating, there are times when the difference between the two measured values compared in the comparing step (S13) is greater than the predetermined difference Ts, due to an error in the measurement of the temperature measuring unit <NUM>.

In this case, when immediately determining whether the cooling fan <NUM> stops operating, the controller <NUM> may assume that the cooling fan <NUM> stops operating and stop the cooking operation or the self-cleaning operation of the cooking appliance even though the cooling fan <NUM> operates actually. If this happens repeatedly, the cooking operation or the self-cleaning operation of the cooking appliance may not be properly performed, thereby degrading reliability of the cooking appliance.

Considering this, when the high-temperature detection state occurs at least two or more consecutive times, it may be determined that the cooling fan <NUM> stopped operating.

Without a failure of the temperature measuring unit <NUM>, the high-temperature detection state hardly occurs consecutively and repeatedly due to a temporary error in the measurement of the temperature measuring unit <NUM>. Further, it is impossible that the high-temperature detection state occurs three or more consecutive times due to a temporary error in the measurement of the temperature measuring unit <NUM>. Thus, when the high-temperature detection state occurs three or more consecutive times, it is reasonable to determine that the cooling fan <NUM> stops operating.

At the predetermined times set to five or more times, more time may be taken to determine whether the cooling fan <NUM> stops operating without improving accuracy of determining whether the cooling fan <NUM> stops operating than at the predetermined times set to two to four times. As the time taken to determine whether the cooling fan <NUM> stops operating increases, the electronic components may be exposed to a high-temperature environment for a longer period of time and more likely to fail.

Considering this, the predetermined times may be set to two to four times, preferably, three times, for example. As a result, the controller <NUM> may determine whether the cooling fan <NUM> stops operating accurately and quickly.

When the difference between the current value Tc and the previous value Ta is the predetermined difference Ts or less in the determining step (S20), a count of the predetermined times may be reset, and the logic of detecting a failure of the cooling fan <NUM> may start again from the beginning.

When the conditions for determining the stop of the operation of the cooling fan <NUM> are all satisfied in the determining step (S20), the controller <NUM> may assume that the cooling fan <NUM> stops operating (S25), and may stop the cooking appliance from operating (S30). When determining that at least any one of the cooling fan <NUM> of the first unit <NUM> and the cooling fan <NUM> of the second unit <NUM> stops operating in the determining step (S20), the controller <NUM> may stop the operations of all the units currently operating. Accordingly, all the heating units H operating may stop operating, and the circuit board <NUM> and the components mounted onto the circuit board <NUM> may also stop operating.

When the cooking appliance continues to perform the cooking operation in a state where the cooling fan <NUM> stops operating, temperatures of the electronic components such as the circuit board <NUM> and the like may excessively increase. If left in this state, the electronic components may fail. Additionally, it is undesirable to keep the cooking appliance performing the cooking operation when the cooling fan <NUM> is out of order.

When it is determined that the cooling fan <NUM> is out of order, the cooking appliance may stop the cooking operation. Accordingly, even when the electronic components do not cool properly due to the failure of the cooling fan <NUM>, an excessive increase in the temperatures of the electronic components, or the failure of the electronic components caused by the increase in the temperatures may be prevented.

Further, the failure of the cooling fan <NUM> may be determined based on the results of the temperature measuring unit <NUM>'s measurement of temperatures. Accordingly, the failure of the cooling fan <NUM> may be quickly determined.

That is, the cooking appliance may quickly determine whether the electronic components cool properly and may stop a cooking operation, when the electronic components do not cool properly due to the failure of the cooling fan <NUM>, thereby preventing the electronic components from overheating and failing.

It is noteworthy that the determination on whether the cooling fan <NUM> fails is made depending on an increase per unit time in temperature. Determining whether the cooling fan <NUM> fails depending on an increase per unit time is one thing, and determining whether the cooling fan <NUM> fails depending on whether a temperature of the electronic component space 30a, 30b reaches a certain temperature is another.

The method of determining whether the cooling fan <NUM> fails depending on whether a temperature of the electronic component space 30a, 30b reaches a certain temperature may hardly be applied to various types of oven having different sizes of cooking space and heat generating capacity. The temperatures of the electronic component space 30a,30b, which are measured when the cooling fan <NUM> fails, may differ depending on capacity and heat generating capacity of an oven, the conditions for cooling of the electronic component space 30a, 30b, and the like.

To apply the method of determining whether the cooling fan <NUM> fails depending on whether a temperature of the electronic component space 30a, 30b reaches a certain temperature, a temperature (hereinafter, a "highest set temperature") as a reference for determining whether the cooling fan <NUM> fails needs to be set differently for each sort of ovens.

That is, in the method of determining whether the cooling fan <NUM> fails depending on whether a temperature of the electronic component space 30a, 30b reaches a highest set temperature, the highest set temperature needs to be set to a different value for each sort of ovens, causing inconvenience.

Additionally, in the method of determining whether the cooling fan <NUM> fails depending on whether a temperature of the electronic component space 30a, 30b reaches a highest set temperature, when the first unit <NUM> is stacked on top of the second unit <NUM> as shown, it is difficult to find a failure of the cooling fan <NUM> installed in the second unit <NUM>.

A temperature of the electronic component space 30a, 30b of the second unit <NUM>, measured by the temperature measuring unit <NUM> in the first unit <NUM>, may be less than an actual temperature of the electronic component space 30a, 30b of the second unit <NUM>.

When the highest set temperature is set with respect to a temperature of the electronic component space 30a, 30b of the first unit <NUM>, a temperature that is measured by the temperature measuring unit <NUM> when the cooling fan <NUM> of the second unit <NUM> fails may rarely reach the highest set temperature. Thus, even when the cooling fan <NUM> of the second unit <NUM> fails, it is difficult to find a failure of the cooling fan <NUM>.

Considering this, a highest set temperature during an operation of the first unit <NUM>, and a highest set temperature during an operation of the second unit <NUM> may be set differently. However, it is difficult to find a failure of the cooling fan <NUM> of the second unit <NUM> in this way when the first unit <NUM> and the second <NUM> operate at the same time.

Determination on whether the cooling fan <NUM> fails or not may be made depending on an increase per unit time in temperature. That is, the coking appliance may check whether a temperature difference between two temperature values, which are measured at different time points having the time difference of the second predetermined time, is the predetermined difference Ts or greater to determine whether the cooling fan <NUM> fails.

Regardless of different sizes of a cooking space and heat generating capacity, ovens have a temperature increase rate within a similar range. Naturally, most ovens having different sizes of cooking space and heat generating capacity have similar tendency in a change in temperatures of the electronic component space 30a, 30b after the time point when the temperature of the electronic component space 30a, 30b reaches the predetermined comparison initiation temperature.

Considering this, the cooking appliance may determine whether the cooling fan <NUM> fails depending on an increase per unit time in temperature, thereby making it possible to apply a control operation to stop the cooking appliance from operating at a time of failure of the cooling fan <NUM> to various types of ovens having different capacity and hear generation quantity on the same basis.

Additionally, the cooking appliance may effectively find out a failure of the cooling fan <NUM> installed in the second unit <NUM> in the lower portion of the cooking appliance in which the first unit <NUM> is stacked on top of the second unit <NUM>.

As long as a current temperature is the predetermined comparison initiation temperature or greater, a failure of the cooling fan <NUM> may be found based on an increase per unit time in temperature regardless of the current temperature.

For example, even if the temperature measured by the temperature measuring unit <NUM> when the cooling fan <NUM> fails during an operation of the second unit <NUM> is less than the temperature measured by the temperature measuring unit <NUM> when the cooling fan <NUM> operates normally during an operation of the first unit <NUM>, as long as an increase per unit time in temperature is the predetermined difference Ts or greater, the cooking appliance may determine that the cooling fan <NUM> stops operating and may stop its operation.

Claim 1:
A cooking appliance comprising:
a casing (<NUM>) provided with a cooking space (<NUM>) therein;
a heating unit (H) configured to heat the cooking space (<NUM>):
an electronic component space (<NUM>) provided outside the casing (<NUM>);
a circuit board (<NUM>) disposed in the electronic component space (<NUM>);
a supporter (<NUM>) configured to space the circuit board (<NUM>) from the casing (<NUM>) and support the circuit board (<NUM>);
a cooling fan (<NUM>) configured to generate a flow of cool air passing through a cool air passage (<NUM>) that is surrounded by the casing (<NUM>), the circuit board (<NUM>) and the supporter (<NUM>);
a temperature measuring unit (<NUM>) installed at the supporter (<NUM>) and configured to measure temperatures in the cool air passage (<NUM>); and
a controller (<NUM>) configured to control an operation of the heating unit (H), wherein, the electronic component space (<NUM>) is disposed upon the casing (<NUM>), and
the supporter (<NUM>) comprises an air guide (<NUM>) disposed laterally adjacent to the circuit board (<NUM>), protruding from the casing (<NUM>) upward, and blocking a lateral side of the cool air passage (<NUM>),
characterized in that controlling the operation of the heating unit (H) by the controller (<NUM>) is performed based on an increase rate of temperatures measured by the temperature measuring unit (<NUM>), and
the temperature measuring unit (<NUM>) is installed at the air guide (<NUM>).