HK40048105B - Cooking device - Google Patents

Description

Heating cooker

Technical Field

This disclosure relates to a heating cooker for heating and cooking an object housed in a heating chamber.

Background Technology

In heating cookers, various functions such as microwave heating, radiant heating, hot air circulation heating, and steam heating are provided to ensure appropriate heating and cooking corresponding to the cooking content of the food being heated (see, for example, Patent Document 1). For optimal heating and cooking of the food using these functions, temperature management within the heating chamber where the food is housed is crucial. In temperature management within the heating chamber, a temperature detection unit is particularly required to possess the following qualities: high accuracy in detecting the temperature of the area containing the food being heated, and excellent responsiveness for instantaneous detection without any time lag.

Furthermore, in a heating cooker, if microwave heating is performed in an empty state inside the heating chamber without any food being heated, this is known as "dry heating." In this case, the microwaves emitted into the heating chamber are not absorbed and instead return as reflected waves to the microwave generating unit, potentially damaging it. Therefore, it is essential to immediately detect such "dry heating" and stop the heating process, and notify the user.

Existing technical documents

Patent documents

Patent Document 1: International Publication No. 2015/118867

Summary of the Invention

As mentioned above, temperature management within the heating chamber is crucial in heating cookers, requiring a temperature detection unit with excellent accuracy and responsiveness. Furthermore, reliably detecting "dry heating" states in heating cookers, especially when performing microwave heating, is an important issue to prevent actual "dry heating."

The purpose of this disclosure is to provide a heating cooker capable of accurately detecting the temperature inside the heating chamber, and being able to detect it immediately when microwave heating is performed in a "dry" state.

One aspect of the heating cooker disclosed herein includes: a heating chamber for housing an object to be heated; a circulating fan for drawing in air from the heating chamber and blowing the drawn-in air into the heating chamber; an internal flow path forming section disposed inside the heating chamber and defining the flow rate and direction of the air blown from the circulating fan into the heating chamber; and an internal temperature detection sensor disposed inside the heating chamber within the air circulation path formed by the internal flow path forming section, and positioned at a predetermined distance from the internal flow path forming section.

According to this disclosure, the temperature inside the heating chamber can be detected with high precision, and it can be detected immediately when microwave heating is performed in a "dry burning" state.

Attached Figure Description

Figure 1 is a perspective view showing the appearance of the heating cooker according to Embodiment 1 of the present invention.

Figure 2 is a perspective view showing the state of the heating cooker in Embodiment 1 with the door open.

Figure 3 is a longitudinal sectional view of the heating cooker of Embodiment 1.

Figure 4 is a magnified cross-sectional view of the temperature sensor inside the chamber.

Figure 5 is a front view showing the inner wall that forms the back of the heating chamber.

Figure 6 is a front view showing a portion of the hot air circulation heating section in the hot air circulation area.

Figure 7 is an exploded perspective view of the hot air circulation heating section in the hot air circulation area.

Figure 8 is a perspective view of the hot air circulation heating section in the hot air circulation area.

Figure 9 is a side sectional view showing the configuration of the flow path forming section inside the heating chamber.

Figure 10 is a cross-sectional view of the flow path formation section inside the heating chamber near the top surface of the heating chamber, viewed from above.

Figure 11 is a perspective view of the air duct in the flow path forming section of the heating chamber.

Figure 12A is a top view showing the air duct of the flow path forming part in the heating chamber.

Figure 12B is a front view of the air duct forming part of the heating chamber.

Figure 12C is a rear view of the air duct in the flow path forming section of the heating chamber.

Figure 13 is a schematic cross-sectional view showing the flow of air convecting inside the heating chamber by driving a circulating fan in the structure of the heating cooker of Embodiment 1.

Figure 14 is a top view of the bottom of the heating chamber from above.

Figure 15 shows the location of the temperature detection sensor inside the chamber near the top surface of the heating chamber during the verification experiment.

Figure 16 is a graph showing the results of an experiment comparing the temperature inside the chamber with the center temperature of the heating chamber under various heating modes by placing the temperature sensor inside the chamber at a specific location.

Detailed Implementation

Hereinafter, as specific embodiments of the heating cooker of this disclosure, a heating cooker having microwave heating, radiant heating, and hot air circulation heating functions will be described with reference to the accompanying drawings. Furthermore, the heating cooker of this disclosure is not limited to the structure of the heating cooker described in the following embodiments, but includes structures based on technologies with the same technical concepts as those described in the following embodiments.

Furthermore, the numerical values, shapes, structures, steps (processes, modes), and order of steps shown in the following embodiments are merely examples and are not intended to limit the invention to the scope of this disclosure. Elements in the following embodiments that are not described in the independent claims representing the highest-level concept are described as arbitrary elements. Additionally, in each embodiment, the same reference numerals are used to denote the same elements, and descriptions are sometimes omitted. Furthermore, for ease of understanding, the drawings schematically represent the respective constituent elements.

First, various methods of heating cooking appliances disclosed herein are illustrated.

The heating cooker of the first aspect of this disclosure includes: a heating chamber for housing an object to be heated; a circulating fan for drawing in air from the heating chamber and blowing the drawn-in air into the heating chamber; an internal flow path forming section disposed inside the heating chamber and defining the flow rate and direction of the air blown from the circulating fan into the heating chamber; and an internal temperature detection sensor disposed inside the heating chamber within the air circulation path formed by the internal flow path forming section, and positioned at a predetermined distance from the internal flow path forming section.

In the second aspect of the heating cooker disclosed herein, in the first aspect, the internal temperature detection sensor is configured to operate when the circulating fan is running.

In the second aspect of the third-party heating cooker disclosed herein, the wall constituting the heating chamber further has multiple openings, including a first opening group and a second opening group. The first opening group is disposed in the central region of the wall, drawing in air from the heating chamber by means of the operation of the circulating fan. The second opening group is disposed near the top surface of the wall, blowing air towards the vicinity of the top surface of the heating chamber by means of the operation of the circulating fan. The internal flow path forming part and the internal temperature detection sensor are disposed near the top surface of the heating chamber.

The heating cooker of the fourth aspect of this disclosure, in the third aspect, includes a flow path forming portion in the heating chamber comprising: an air duct that accelerates the flow rate of the air blown by the circulating fan toward the vicinity of the top surface of the heating chamber; and at least one air guide that directs the blowing direction from the air duct at least downward toward the heating chamber.

In the fifth aspect of the heating cooker disclosed herein, in the fourth aspect, the internal temperature detection sensor is configured in the circulation path from the air blown out of the air duct to the air guide component.

In the fifth embodiment of the heating cooker of the sixth aspect of this disclosure, the at least one air guide component has a first air guide component, in the circulation path, the air blown from the air duct first reaches the first air guide component of the at least one air guide component, and the internal temperature detection sensor is disposed at a predetermined distance from the position of the first air guide component.

In the seventh aspect of the heating cooker disclosed herein, in the sixth aspect, the detection end of the internal temperature detection sensor is disposed at a height of half the protrusion height of the first air guide member protruding from the top surface of the heating chamber.

In any of the first to seventh embodiments of the heating cooker disclosed herein, the heating cooker further comprises a hot air circulation heating unit, the hot air circulation heating unit including a heat source for circulating hot air to heat an object housed in the heating chamber. The circulation fan and the flow path forming portion within the heating chamber are included in the hot air circulation heating unit.

The heating cooker of the ninth aspect disclosed herein, in any of the first to eighth aspects, further includes a microwave heating unit, which comprises a microwave generating unit and a microwave supply unit for microwave heating an object housed in the heating chamber. The chamber temperature detection sensor is configured to operate as a detector for detecting "dry heating" during microwave heating.

In any of the first to ninth embodiments of the heating cooker disclosed herein, the heating cooker further comprises a radiant heating unit, which includes a heat source for radiantly heating an object housed in the heating chamber. The internal temperature detection sensor is disposed directly above the heat source of the radiant heating unit, located near the top surface of the heating chamber.

(Implementation Method 1)

Hereinafter, the heating cooker according to Embodiment 1 of the present invention will be described with reference to the accompanying drawings. FIG1 is a perspective view showing the appearance of the heating cooker 1 of Embodiment 1. In the heating cooker 1 shown in FIG1, the door 4 provided on the front is in a closed state. FIG2 is a perspective view showing the state in which the door 4 of the heating cooker 1 of Embodiment 1 is opened.

The heating cooker 1 in Embodiment 1 is a commercial heating cooker, for example, a cooker capable of heating with a high output used in convenience stores or food stores. In the heating cooker 1, microwave heating, radiant heating, and hot air circulation heating are selectively performed individually, sequentially, or in parallel, depending on the cooking content.

As shown in Figures 1 and 2, the heating cooker 1 includes: a main body 2 having a heating chamber 5; a mechanical chamber 3 located below the main body 2 and supporting the main body 2; and a door 4 provided on the front surface of the main body 2 in an openable and closable manner. Additionally, an operation display 6 is provided on the front of the main body 2 for displaying the user's settings and settings for the heating cooker 1.

The heating chamber 5 of the main body 2 has a roughly rectangular space with an opening at the front. It is sealed by closing the front opening using a door 4, and houses the food to be heated. The food stored in the heating chamber 5 is heated and cooked using a hot air circulation heating mechanism located at the rear of the heating chamber 5, a radiant heating mechanism located near the top surface, and a microwave heating mechanism located below the bottom surface of the heating chamber 5. The bottom surface of the heating chamber 5 is made of a material that easily transmits microwaves, such as glass or ceramic.

The heating chamber 5 is internally configured to house a shelf 7 for holding the object to be heated and a tray 8 positioned below the shelf 7 to receive grease or other substances dripping from the object. The shelf 7 is, for example, a stainless steel wire frame, composed of a mesh structure for holding the object to be heated. The tray 8 is made of ceramic, specifically cordierite (a ceramic composed of magnesium oxide, aluminum oxide, and silicon oxide). Cordierite possesses properties of low thermal expansion and excellent thermal shock resistance.

Figure 3 is a longitudinal sectional view of the heating cooker 1 according to Embodiment 1. In Figure 3, a door 4 is provided on the right side, which is the front of the heating cooker 1. In this specification, the side with the door 4 of the heating cooker 1 is described as the front (front view), and its opposite side (the left side in Figure 3) is described as the rear (back view).

As shown in Figure 3, a grid heater 9 constituting the radiant heating section 20 is provided near the top surface of the heating chamber 5. The grid heater 9, which serves as a heat source, is composed of a sheathed heater and is positioned near the top surface with a curved shape (see Figure 10). The grid heater 9 is driven and controlled in a grid mode (radiant heating operation) where the food housed in the heating chamber 5 is heated and cooked using radiant heat.

A microwave heating unit 21 is provided in the mechanical chamber 3 located below the bottom surface of the heating chamber 5. The main components of the microwave heating unit 21 include a magnetron 15 (a microwave generating unit), an inverter 16 (driving the magnetron 15), and a cooling fan 17 (cooling the internal components of the mechanical chamber 3), all driven and controlled by a control unit described later. The microwave heating unit 21 also includes a waveguide 18 that guides the microwaves generated by the magnetron 15 towards the heating chamber 5, and a microwave supply unit 19 that radiates the microwaves guided by the waveguide 18 into the interior of the heating chamber 5. The microwave supply unit 19 is located at the center of the bottom surface of the heating chamber 5 and has an opening forming the upper surface of the end of the waveguide 18. Furthermore, a stirrer 23 is provided above the microwave supply unit 19 to stir the microwaves radiated from it. The stirrer 23 is driven to rotate by a stirrer drive unit (motor: not shown) located within the mechanical chamber 3 and has blades for stirring the radiated microwaves. Therefore, in the heating cooker 1 of Embodiment 1, the microwaves after stirring are uniformly radiated from below the bottom surface of the heating chamber 5 into the interior of the heating chamber 5.

In addition, in the heating cooker 1 of Embodiment 1, in addition to the radiant heating unit 20 and the microwave heating unit 21, a hot air circulation heating unit 22 is also provided as the heating and cooking source, and is driven and controlled by a control unit (not shown) including a microcomputer. As part of the structure of the hot air circulation heating unit 22, a convection heater 10, serving as a heat source for hot air circulation heating, a circulating fan 11, serving as an air supply source, and a fan drive unit 12 (motor) for driving the circulating fan 11 are provided behind the back of the heating chamber 5. Multiple openings are formed in the inner wall 5a, which forms the back of the heating chamber 5. Through these openings, air from the heating chamber 5 is drawn in and blown out into the heating chamber 5 by means of the convection heater 10 and the circulating fan 11. Furthermore, the hot air circulation heating unit 22 includes an air duct 13 and an air guide member 14, described later. The air duct 13 and the air guide member 14 are located near the top surface of the heating chamber 5, defining the airflow speed and blowing direction towards the heating chamber 5. In this disclosure, the air duct 13 and the air guide component 14 are disposed inside the heating chamber 5, forming an internal flow path forming section 60 that defines the flow rate and direction of the air blown from the circulating fan 11 into the heating chamber 5. The internal flow path forming section 60 forms a circulation path for the air blown into the heating chamber 5.

As described above, in the heating cooker 1 of Embodiment 1, a radiant heating unit 20, a microwave heating unit 21, and a hot air circulation heating unit 22 are provided for heating and cooking the food stored in the heating chamber 5. In this heating cooker 1, an internal temperature detection sensor 50 is provided near the top surface of the heating chamber 5 to detect the internal temperature of the heating chamber 5. Furthermore, a thermistor is used as the internal temperature detection sensor 50.

Figure 4 is an enlarged cross-sectional view of the chamber temperature sensor 50. As shown in Figure 4, the thermistor chip 51, which serves as the sensing end of the chamber temperature sensor 50, is housed inside the protruding end of a protective tube 52 (e.g., a thin-walled stainless steel tube) that is closed at the end. The gap between the thermistor chip 51 and the protective tube 52 is filled with a heat-resistant inorganic filler 53 with excellent thermal conductivity. The chamber temperature sensor 50 configured in this way is positioned approximately at the center of the top surface of the heating chamber 5 (see Figure 3). Furthermore, a smaller thermal time constant, which affects the responsiveness of the thermistor, is a superior characteristic; however, in this configuration, the value, including the protective tube 52, is set to within 60 seconds.

[Location of the internal temperature sensor 50]

The position of the chamber temperature sensor 50 is closely related to the positions of the various components in the aforementioned radiant heating unit 20, microwave heating unit 21, and hot air circulation heating unit 22. Specifically, the chamber temperature sensor 50 is positioned at a specific location within the circulation path formed by the hot air circulation heating unit 22. The temperature detection operation of the chamber temperature sensor 50 is performed when at least the circulation fan 11 of the hot air circulation heating unit 22 is running; therefore, the structure of the hot air circulation heating unit 22 will be described first.

[Structure of hot air circulation heating unit 22]

The hot air circulation heating unit 22 has a convection heater 10, which serves as the heat source for hot air circulation heating, a circulating fan 11, which serves as the air supply source, and a fan drive unit 12 (motor) for driving the circulating fan 11, etc., provided behind the heating chamber 5. Multiple openings are formed in the inner wall 5a forming the back of the heating chamber 5. The convection heater 10, circulating fan 11, fan drive unit 12, and other components of the hot air circulation heating unit 22 are arranged in the hot air circulation heating area located behind this inner wall 5a. Furthermore, as components of the hot air circulation heating unit 22, there are air ducts 13 and air guide components 14 located near the top surface inside the heating chamber 5, which form the flow path forming section 60 within the heating chamber. Details regarding the arrangement, function, and structure of the air duct 13 and air guide components 14, which form the flow path forming section 60 within the heating chamber, will be described later.

Figure 5 is a front view showing the inner wall 5a, which forms the back of the heating chamber 5. As shown in Figure 5, multiple openings 25 (25a, 25b) are formed in the central side region A and the top surface near region B of the inner wall 5a by punching. These openings 25 have an opening shape that prevents microwaves from radiating into the heating chamber 5 from leaking out. The first opening 25a, formed in the central portion of the inner wall 5a, i.e., the central side region A, serves as an intake port for drawing air from the heating chamber 5 in the rearward direction. In addition, the second opening 25b, formed in the top surface near region B, which extends in the width direction (left-right direction) near the top surface of the inner wall 5a, serves as an outlet for blowing air (hot air) into the heating chamber 5. In the structure of Embodiment 1, an example is given where the first opening 25a and the second opening 25b have the same opening shape, but the desired shape is formed according to the specifications (suction volume/blowing volume, etc.) of the heating cooker 1.

Figure 6 is a front view showing a portion of the hot air circulation heating unit 22 arranged in the hot air circulation heating area. Figure 6 shows the state with the inner wall 5a removed, and the position of the heating chamber 5 is near the front side of Figure 6. Figure 7 is an exploded perspective view of the hot air circulation heating unit 22 arranged in the rear direction of the inner wall 5a. As shown in Figures 6 and 7, a convection heater 10 is arranged in the rear direction of the inner wall 5a in the hot air circulation heating unit 22. The convection heater 10 is constructed by forming a sheathed heater in a vortex shape. The vortex portion of the convection heater 10 is opposite to the central side region A of the inner wall 5a, and the air drawn in from the first opening 25a of the central side region A is heated by the convection heater 10.

A circulating fan 11 for drawing in air from the heating chamber 5 and a fan drive unit (motor) 12 are provided on the rear side of the convection heater 10. The circulating fan 11 is a centrifugal fan, which draws in air from its central part and blows it out in a centrifugal direction. The air drawn in from the heating chamber 5 by the circulating fan 11 is heated by the convection heater 10 to become hot air. It passes through the catalyst 26 for purification and is drawn out in a centrifugal direction by the circulating fan 11 inside the hot air circulation frame 28.

An air guiding frame 27 and a hot air circulation frame 28, which have air guiding functions, are provided around the convection heater 10 and the circulating fan 11. The air guiding frame 27 has: a first air guide 27a, which is a circular frame arranged to surround the convection heater 10; and a second air guide 27b, which guides the air blown towards the centrifugal direction of the circulating fan 11 to be blown along the top surface of the heating chamber 5. The air guiding frame 27 is fixed to the hot air circulation frame 28, which is a quadrilateral frame shaped to surround the air guiding frame 27. The area defined by the first air guide 27a of the circular frame is opposite to the central part of the inner wall 5a, i.e., the central side region A. Therefore, the air drawn in from the heating chamber 5 through the central side region A of the inner wall 5a is guided to the position of the convection heater 10 and heated, becoming hot air, and then drawn into the central part of the circulating fan 11. The hot air drawn in from the central part of the circulating fan 11 is guided by the second air guide 27b arranged around the circulating fan 11 to be blown along the top surface.

The hot air guided towards the vicinity of the top surface by the second air guide 27b comes into contact with the inner surface of the hot air circulation frame 28 near the top surface and is delivered to the heating chamber side (front view). A plate-shaped third air guide 28a is provided on the inner surface of the hot air circulation frame 28 near the top surface to blow the hot air delivered near the top surface by the second air guide 27b approximately evenly along the top surface of the heating chamber 5. The third air guide 28a in Embodiment 1 is described as a specific example, but multiple third air guides may also be arranged side-by-side. In the structure of Embodiment 1, since the rotation direction of the circulating fan 11 is clockwise when viewed from the heating chamber side, the third air guide 28a extends along the inner surface of the hot air circulation frame 28 near the top surface at approximately one-third of the distance from the left end when viewed from the heating chamber side, guiding the hot air towards the heating chamber side. The position of the third air guide 28a is appropriately set according to the specifications of the circulating fan 11 and the shape of the hot air circulation frame 28. Furthermore, the hot air circulation frame 28 is disposed inside the insulation frame 30 through the insulation material 29. Therefore, the heat from the hot air circulation frame 28 will not be transferred to the outside of the device.

Figure 8 is a perspective view of the hot air circulation heating unit 22 in the hot air circulation area (the area behind the inner wall 5a). As shown in Figure 8, air drawn in through the central part of the hot air circulation area (the central side area A of the inner wall 5a) is guided by the first air guide 27a and heated into hot air by the convection heater 10, and then drawn into the circulation fan 11. The hot air drawn into the circulation fan 11 is blown out towards the vicinity of the top surface of the heating chamber 5 by means of the second air guide 27b disposed on the outside of the circulation fan 11 and the hot air circulation frame 28 (including the third air guide 28a).

[Position of the internal temperature sensor 50 relative to the air duct 13 and air guide component 14]

As described above, the hot air blown towards the vicinity of the top surface of the heating chamber 5 flows in a circulation path formed within the internal space of the heating chamber 5 via the air duct 13 and the air guide component 14 in the hot air circulation heating section 22 on the side of the heating chamber. These air ducts 13 and air guide components 14 constitute the internal flow path forming section 60 of the heating chamber.

Figure 9 is a side sectional view showing the arrangement of the air duct 13 and air guide component 14 in the internal flow path forming section 60 of the heating chamber 5. In Figure 9, the right side of the heating chamber 5 is the rear-facing area where the convection heater 10 and the circulating fan 11 are installed, and the left side of the heating chamber 5 is the front-facing area. Figure 9 shows the main structure arranged inside the heating chamber 5, omitting other structures. Figure 10 is a sectional view of the area near the top surface of the heating chamber 5 viewed from above, showing the arrangement of the air duct 13, air guide component 14, and grille heater 9, etc. In Figure 10, hot air flows from the upper side to the lower side.

Hot air blown from near the top surface of the inner wall 5a of the heating chamber 5 is adjusted to the desired air pressure (flow velocity) by the air duct 13 and the air guide component 14, and flows in the circulation path inside the heating chamber 5. The air duct 13 is structured such that the hot air blown from the area B near the top surface of the inner wall 5a is concentrated and throttled, and blown towards the grille heater 9 located near the top surface of the heating chamber 5 at the desired air pressure.

Figure 11 is a perspective view of the air duct 13. Figure 12A is a top view of the air duct 13, Figure 12B is a front view of the air duct 13, and Figure 12C is a rear view. As shown in Figures 11, 12A, 12B, and 12C, the outlet 13b of the air duct 13 is significantly smaller than the inlet 13a, forming a smaller cross-sectional area ratio of 30% to 50%. As a result, a high-velocity airflow with greater force is blown out from the outlet 13b of the air duct 13. In addition, a partition plate 13c is provided in the air duct 13 to divide the internal space of the air duct 13 into two parts. The partition plate 13c is arranged such that the airflow blown out from the outlet 13b of the air duct 13 is approximately equal on both sides. In the structure of Embodiment 1, the air delivered from the circulating fan 11 enters at an angle relative to the inlet 13a of the air duct 13, therefore the partition plate 13c is offset from the center position. That is, the upstream side of the inlet 13a (the opening portion on the right side of the inlet 13a in Figure 11) is designed to be slightly smaller.

As shown in Figures 9 and 10, the air blown forward from the outlet 13b of the air duct 13 is substantially parallel to the top surface of the heating chamber 5. A grille heater 9, which extends in a curved manner parallel to the top surface of the heating chamber 5, is provided near the top surface of the heating chamber 5, so the air from the outlet 13b is blown onto the grille heater 9. Two air guide members 14 (14a, 14b) are arranged side-by-side between the curved portions on the upstream and downstream sides of the grille heater 9. Therefore, the air blown towards the top surface of the heating chamber 5 contacts the first air guide member 14a and the second air guide member 14b in sequence. In the structure of Embodiment 1, a structure with two air guide members 14 (14a, 14b) on the upstream and downstream sides is described, but this disclosure is not limited to two; the appropriate number is set according to the specifications of the heating cooker, the shape of the heating chamber 5, etc.

In the structure of Embodiment 1, the first air guide component 14a and the second air guide component 14b are fixed to the top wall of the heating chamber 5 and are respectively arranged to face the outlet 13b of the air duct 13. The center of the outlet 13b of the air duct 13 in the width direction is located on the center line P of the heating chamber 5 from the back to the front (see FIG10). In addition, the centers of the first air guide component 14a and the second air guide component 14b in the width direction are located on the center line P, and the first air guide component 14a and the second air guide component 14b extend orthogonally to the center line P. Therefore, the first air guide component 14a and the second air guide component 14b have contact surfaces orthogonal to the actual blowing direction of the air blown out from the outlet 13b of the air duct 13 (the downward direction in FIG10).

As shown in Figure 9, the height (protrusion dimension from the top surface) of the first air guide component 14a and the second air guide component 14b is set such that the upstream first air guide component 14a is lower than the downstream second air guide component 14b, and the lower ends of the first air guide component 14a and the second air guide component 14b are located below the lower surface of the grille heater 9. Furthermore, the width (dimension in the width direction of the heating chamber 5) of the first air guide component 14a and the second air guide component 14b is set such that the first air guide component 14a is narrower than the second air guide component 14b. With this configuration and arrangement of the first air guide component 14a and the second air guide component 14b, the air blown from the outlet 13b of the air duct 13 sequentially contacts the first air guide component 14a and the second air guide component 14b, blowing downwards approximately from the top surface of the heating chamber 5.

The chamber temperature sensor 50 is disposed in the circulation path from the outlet 13b of the chamber 13 to the first air guide component 14a, relative to the air duct 13 and the air guide components 14b configured as described above. In the structure of Embodiment 1, it is disposed directly in front of the upstream side of the first air guide component 14a. Specifically, the thermistor chip 51, which is the detection end of the chamber temperature sensor 50, is preferably disposed at a position 5mm to 15mm upstream of the contact surface of the first air guide component 14a. In this disclosure, the position 5mm to 15mm upstream of the contact surface of the first air guide component 14a is a position near the first air guide component 14a, indicating a position directly in front of the first air guide component 14a. That is, in this disclosure, "nearby of the first air guide component 14a" refers to "a position 5mm to 15mm away from the first air guide component 14a", and "the position directly in front of the first air guide component 14a" refers to "a position 5mm to 15mm away from the first air guide component 14a upstream". Furthermore, in this embodiment, "nearby of the first air guide component 14a" is also referred to as "a position separated from the first air guide component 14a by a predetermined distance", and "the position directly in front of the first air guide component 14a" is also referred to as "a position separated from the first air guide component 14a by a predetermined distance upstream".

Furthermore, the thermistor chip 51 of the internal temperature sensor 50 is positioned at approximately half the height of the contact surface of the first air guide component 14a. Specifically, if the height of the first air guide component 14a (the protruding dimension from the top surface) is set to 25mm to 33mm, then the height of the thermistor chip 51 (the protruding length from the top surface) is preferably set to 12mm to 16mm.

As described above, the internal temperature detection sensor 50 is positioned relative to the air duct 13 and the air guide component 14 at a specific location. In the heating cooker 1 of Embodiment 1, the internal temperature detection sensor 50 detects the internal temperature at least when an air circulation path is formed inside the heating chamber 5 by the driving of the circulating fan 11. That is, the internal temperature detection sensor 50 detects the internal temperature when it comes into contact with the air circulating inside the heating chamber 5. In the heating cooker 1 of Embodiment 1, when the circulating fan 11 is not driven (i.e., when no heating or cooking is being performed), the temperature detection operation of the internal temperature detection sensor 50 stops. This is to avoid the risk that, although no heating or cooking is being performed when the circulating fan 11 is stopped, if temperature detection continues, the internal temperature may be mistakenly detected as an abnormal temperature due to the residual heat on the surface of the grille heater 9 and the effect of the stopping of the circulating fan 11.

Figure 13 schematically illustrates, with arrows, the airflow within the heating chamber 5 driven by the circulating fan 11 in the structure of the heating cooker of Embodiment 1. As shown in Figure 13, the chamber temperature sensor 50 is disposed in direct contact with the air blown out from the outlet 13b of the air duct 13. Specifically, the structure is such that the chamber temperature sensor 50 is reliably exposed to the circulating air that passes through the heating chamber 5 and is blown out from the outlet 13b of the air duct 13 again through the hot air circulation heating area from the central side region of the inner wall. That is, the chamber temperature sensor 50 is disposed in the circulation path inside the heating chamber 5.

As described above, in the structure of the heating cooker of Embodiment 1, the circulating fan 11 is configured to operate continuously during the period when the temperature inside the chamber should be detected, and the stopping of the circulating fan 11 means the cessation of heating and cooking. In the heating cooker of Embodiment 1, the circulating fan 11 operates even when the hot air circulation heating unit 22 is not operating (when the convection heater is not operating) during cooking, thus forming an air circulation path at least inside the heating chamber 5.

[Position of the internal temperature sensor 50 relative to the radiant heating element 20]

Next, the position of the chamber temperature detection sensor 50 relative to the radiant heating unit 20 will be explained. As described above, the radiant heating unit 20 is composed of a grille heater 9 disposed near the top surface of the heating chamber 5. As can be seen from Figures 9 and 10, the grille heater 9 is arranged in a meandering manner parallel to the top surface of the heating chamber 5. The grille heater 9 is disposed on approximately the entire surface near the top surface of the heating chamber 5, from the position directly in front of the outlet 13b of the air duct 13 to the vicinity of the door 4 at the front of the heating chamber 5. In addition, as shown in Figure 10, the grille heater 9 has a high density in the area near the outlet 13b and a low density in the area near the door 4. This is set to heat the interior space of the heating chamber 5 at a uniform temperature, taking into account the wind force of the air blown out from the outlet 13b and the position of the air guide member 14. The position of the grille heater 9 in the height direction is simply the height of the outlet 13b of the air duct 13, and any position where the air from the outlet 13b directly contacts the grille heater 9.

Relative to the heat source of the radiant heating section 20 configured as described above, namely the grid heater 9, the chamber temperature detection sensor 50 is disposed directly above (including approximately directly above) the grid heater 9 located upstream of the first air guide member 14a and closest to the contact surface of the first air guide member 14a (see Figure 9).

[Position of the internal temperature sensor 50 relative to the microwave heating element 21]

Next, the position of the internal temperature detection sensor 50 relative to the microwave heating unit 21 will be explained. As described above, the microwave heating unit 21 includes a magnetron 15 as a microwave generating unit, a microwave supply unit 19 for emitting microwaves into the heating chamber 5, etc., and is disposed below the main body 2 of the heating cooker 1, i.e., the mechanical chamber 3.

As shown in Figures 3 and 13 above, an inverter 16 is positioned in front of the magnetron 15 within the machine chamber 3. A cooling fan 17 is located in front of each inverter 16, drawing in external air from the external air intake (not shown) formed in the front cover 24 of the machine chamber 3 and directing it towards the rear of the machine chamber 3. Thus, the cooling fan 17 sequentially cools the inverter 16 and the magnetron 15. The air cooled by the inverter 16 and the magnetron 15 is guided by a duct (not shown) and exhausted from the rear of the heating cooker 1.

Figure 14 is a top view of the bottom surface of the heating chamber 5, showing two magnetrons 15 (15a, 15b), the bottom surface of the heating chamber 5, and waveguides 18 (18a, 18b) arranged side-by-side from the magnetrons 15 (15a, 15b) to the bottom surface of the heating chamber 5. As shown in Figure 14, the two magnetrons 15 (15a, 15b) are arranged side-by-side adjacent to each other at the rear of the machine room 3.

The output ends of each magnetron 15a and 15b are connected to waveguides 18a and 18b arranged side-by-side below the bottom surface of the heating chamber 5. As shown in Figure 14, one end of each waveguide 18a and 18b is connected to each magnetron 15a and 15b, and microwave emission ports 19a and 19b are formed at the other end. The microwave emission ports 19a and 19b of the waveguides 18a and 18b are connected to the microwave supply section 19, which serves as an opening in the bottom surface of the heating chamber 5, thus becoming a supply port (antenna) for supplying microwaves to the heating chamber 5. A stirrer shaft 31 is provided through the microwave emission ports 19a and 19b connected to the microwave supply section 19. The stirrer shaft 31 is the rotation shaft of a stirrer 23 that stirs the microwaves emitted from the microwave supply section 19, and is located below the bottom surface of the heating chamber 5.

In the heating cooker 1 of Embodiment 1 configured as described above, the internal temperature detection sensor 50 is disposed near the top surface opposite the microwave supply unit 19, positioned upstream of the stirrer shaft 31 (see Figure 14). That is, the internal temperature detection sensor 50 is disposed near the top surface opposite the area between the two microwave emission ports 19a and 19b.

[Verification experiment on the optimization of the position of the temperature sensing sensor 50 inside the chamber]

The inventors of this disclosure conducted an experiment to verify that the temperature detected by the internal temperature sensor 50 is closely related to the positions of the various components in the radiant heating unit 20, the microwave heating unit 21, and the hot air circulation heating unit 22. Based on the results of this verification experiment, the internal temperature sensor 50 in the heating cooker 1 of Embodiment 1 described above is positioned at an optimal location that varies proportionally to the internal center temperature (the temperature at approximately the center of the heating space in the heating chamber 5).

The following describes a verification experiment conducted by the inventors of this disclosure to optimize the chamber temperature detection sensor 50. Figure 15 shows the position of the chamber temperature detection sensor 50 near the top surface of the heating chamber 5 during the verification experiment. Figure 15 is a view of the area near the top surface of the heating chamber 5 from above. In this verification experiment, the chamber temperature detection sensor 50 was installed at four locations (A, B, C, D) near the top surface of the heating chamber 5. Furthermore, in Figure 15, hot air flows downwards from the outlet 13b of the air duct 13.

Position A is the position used in Embodiment 1, located upstream of the first air guide member 14a and directly above the grille heater 9. Specifically, the thermistor chip 51, which serves as the detection end of the chamber temperature detection sensor 50, is positioned 10 mm upstream of the contact surface of the first air guide member 14a. Preferably, the distance from the thermistor chip 51 to the grille heater 9 is 3 mm to 6 mm. Because the thermistor chip 51 is close to the grille heater 9, the detection response to the operation of the grille heater 9 is good. Furthermore, by positioning it near the center of the first air guide member 14a, the responsiveness to changes in the airflow of the circulating fan 11 is improved. Additionally, when the height of the first air guide member 14a (the protrusion dimension from the top surface of the heating chamber 5) is 30.5 mm, the height of the thermistor chip 51 (the protrusion length from the top surface of the heating chamber 5) is set to 15.5 mm. These values are examples and are not intended to limit this disclosure. At least as the internal temperature detection sensor 50, a thermistor chip 51 as the detection end can be arranged at a height of about half (including approximately half) of the protrusion height of the first air guide component 14a protruding from the top surface.

Position B is located at the left end of the intake 13a inside the air duct 13 in the width direction. Position C is near the outlet 13b, which is approximately in the center inside the air duct 13. Position D is a position offset from the first air guide member 14a in the width direction (specifically, a position 20 mm away from the left end of the first air guide member 14a), where hot air from the outlet 13b does not directly contact the air. Furthermore, in any of positions (A, B, C, D), the height of the thermistor chip 51 (the protruding length from the top surface of the heating chamber 5) is set to 15.5 mm.

Temperature sensors 50 were installed at four locations (A, B, C, D) shown in Figure 15 to detect temperatures under various heating modes. The results were compared with the temperature at the center of the heating chamber 5 (the temperature at approximately the center of the heating space within the heating chamber 5). The results are shown in the graph in Figure 16.

In Figure 16, the vertical axis represents temperature [°C] and input current [A] for each heating mode, and the horizontal axis represents time [s]. In Figure 16, the solid line represents the center temperature inside heating chamber 5, and the dashed line represents the detected temperature at position A. Additionally, a single-dotted line represents the detected temperature at position B, a double-dotted line represents the detected temperature at position C, and a triple-dotted line represents the detected temperature at position D.

As shown in Figure 16, this verification experiment is a temperature verification experiment conducted under various heating modes used in normal heating and cooking. In the structure of the heating cooker of Embodiment 1 (with a change in the position of the internal temperature sensor 50), each heating mode was executed in the order of "preheating mode" → "grid mode" → "grid + convection mode" → "convection mode". The input current waveforms under each heating mode are shown in thin solid lines at the bottom of Figure 16.

As shown in the graph illustrating the results of the verification experiment in Figure 16, the center temperature inside the heating chamber 5 (solid line) corresponds to the detected temperature at position A (dashed line), exhibiting approximately the same variation. The detected temperatures at other positions B, C, and D show significant differences from the center temperature and different states of change. Therefore, it can be understood that position A—located upstream of the first air guide component 14a in the circulation path from the outlet 13b of the air duct 13 to the first air guide component 14a, and directly above (or approximately directly above) the grille heater 9—is the optimal location for equipping the chamber temperature detection sensor 50 in the heating cooker 1. The verification experiment confirms that by equipping the chamber temperature detection sensor 50 at position A, the center temperature inside the chamber and its changes can be reliably detected with high accuracy and excellent responsiveness.

[Detection of "dry burning" in microwave heating mode]

Furthermore, in the verification experiments conducted by the inventors of this disclosure regarding the internal temperature detection sensor 50, even when cooking was performed using the "microwave heating mode," the temperature of the heated object placed approximately in the center of the heating chamber 5 (internal center temperature) could be detected with high accuracy. Additionally, in the "microwave heating mode," when microwave heating was performed without any heated object inside the heating chamber 5, in a so-called "empty heating" state, the internal temperature detection sensor 50 detected a sharp temperature rise immediately after heating began. When microwave heating of the heated object, the internal center temperature did not rise sharply within one minute of the start of "empty heating," indicating that the chamber was in an "empty heating" state.

Thus, shortly after the start of microwave heating, the chamber temperature sensor 50 detects a sharp temperature rise because the air guide component (14a) located near the chamber temperature sensor 50 is heated by the microwaves. The air guide component (14a) located inside the heating chamber 5 is made of ceramic, which is not a conductor but a dielectric with a low dielectric constant. Specifically, the air duct 13 and the air guide component 14 are made of cordierite (a ceramic composed of magnesium oxide, aluminum oxide, and silicon oxide), which has the characteristics of low thermal expansion and excellent thermal shock resistance.

When microwave heating is performed with a large volume of food to be heated inside the heating chamber 5, the food absorbs microwaves and is heated. However, in a "dry heating" state where the food is not inside the heating chamber 5, a small-capacity air guide (14a) or similar component is heated by microwaves, causing its temperature to rise rapidly. As a result, in the "dry heating" state, regardless of microwave heating, the internal temperature sensor 50 located near the air guide (14a) can detect a rapid temperature rise, thus detecting that the appliance is in a "dry heating" state. In the heating cooker of Embodiment 1, when the internal temperature sensor 50 detects a rapid temperature rise in microwave heating mode, it determines that the appliance is in a "dry heating" state, immediately stops the heating operation, and reports to the user that the appliance is in a "dry heating" state.

As described above, in the structure of the heating cooker of Embodiment 1, by placing the internal temperature detection sensor 50 at position A, the internal temperature detection sensor 50 functions as a "dry burning" detector capable of accurately detecting the internal temperature of the heating chamber 5 and detecting "dry burning" during microwave heating in a short time. Consequently, microwaves guided from the magnetron 15 into the heating chamber 5 are reflected back to the magnetron 15, stopping the heating operation before damaging the magnetron 15.

As described above, in the heating cooker of this disclosure, in order to accurately detect the temperature inside the heating chamber, an internal temperature detection sensor is disposed at a specific position in the circulation path inside the heating chamber, enabling high-precision and reliable detection of the internal temperature and its changes. Furthermore, the heating cooker of this disclosure has a structure capable of reliably detecting "dry heating" in "microwave heating mode".

The heating cooker disclosed herein is configured to utilize various heating functions corresponding to the cooking content of the object being heated, appropriately manage the temperature inside the heating chamber, and perform optimal heating and cooking. According to the structure of the heating cooker disclosed herein, temperature management can achieve the following: high accuracy in detecting the temperature of the area containing the object being heated, and excellent responsiveness enabling instantaneous detection without time lag.

Furthermore, the internal temperature detection sensor in the heating cooker of this disclosure functions only when the circulating fan in the hot air circulation heating unit is running. Therefore, the circulating fan of the heating cooker of this disclosure always runs during the period when the internal center temperature should be detected, and the stopping of the circulating fan means the cessation of heating and cooking.

As described above, in Embodiment 1, a specific structure was described, but the heating cooker disclosed herein is a cooker with high reliability and safety, configured to detect the temperature inside the heating chamber with high accuracy and to immediately detect the "dry burning" state during microwave heating.

The present disclosure has been described in some detail in the embodiments, but these structures are illustrative and the details of the structure should vary in the embodiments. In this disclosure, substitutions, combinations, and changes in the order of elements in the embodiments can be made without departing from the scope and spirit of the claimed disclosure.

The heating cooker disclosed herein is a cooker with high reliability, safety, and market value. It can detect the temperature inside the heating chamber with high precision and can detect the "dry burning" state during microwave heating before it damages the microwave generating part.

Symbol Explanation

1. Heating cooker

2. Main Body

3. Machine Room

4 doors

5 Heating Chamber

5a Libi

6. Operation Display Section

7. Loading rack

8 trays

9. Grille heater

10 Convection Heaters

11. Circulating fan

12 Fan drive unit (motor)

13 Air duct

13a Inlet

13b Blowout

13c partition

14 Air guide components

14a First air guide component

14b Second air guide component

15 Magnetrons

16 Inverters

17 Cooling Fan

18 waveguides

19 Microwave Supply Department

20 Radiant Heating Unit

21 Microwave heating section

22 Hot air circulation heating section

23 Mixer

24 Front Cover

25 Opening

50 Internal Temperature Sensors

51 Thermistor Chip

52 Protective tube

53 Heat-resistant inorganic fillers

60 Heating chamber flow path forming section

Claims (6)

1. A heating cooker, the heating cooker comprising: A heating chamber for storing the objects being heated; A microwave heating unit includes a microwave generating unit and a microwave supply unit for microwave heating an object housed in the heating chamber. A circulating fan draws in air from the heating chamber and blows the drawn-in air out of the heating chamber, thus becoming an air supply source that forms a circulating flow path within the internal space of the heating chamber; A convection heater, located on the rear side of the heating chamber, heats the air drawn in from the heating chamber; A flow path forming section is disposed inside the heating chamber, and specifies the flow rate and direction of the air blown from the circulating fan into the heating chamber; and The internal temperature sensor is disposed inside the heating chamber within the air circulation path formed by the flow path forming part inside the heating chamber, and is positioned at a predetermined distance from the flow path forming part inside the heating chamber. The circulating fan is configured to draw in air from the heating chamber through multiple openings in the central region of the wall forming the heating chamber, and to blow air out of the heating chamber through multiple openings in the region near the top surface of the wall. The flow path forming section inside the heating chamber and the temperature detection sensor inside the chamber are located near the top surface of the wall. The flow path forming section within the heating chamber includes: an air duct that accelerates the airflow velocity from the circulating fan towards the vicinity of the top surface of the heating chamber; and an air guide component that directs the airflow direction from the circulating fan towards the vicinity of the top surface of the heating chamber at least downwards. The air guiding component is formed of a dielectric and has a first air guiding component. In the circulation path, the air blown out from the air duct first reaches the first air guiding component in the air guiding component. The temperature sensor inside the chamber is positioned directly in front of the first air guide component in the circulation path from the top surface of the heating chamber to the air guide component. 2. The heating cooker according to claim 1, wherein, The internal temperature sensor is configured to operate when the circulating fan is running. 3. The heating cooker according to claim 1, wherein, The detection end of the temperature sensor inside the chamber is positioned at half the height of the protrusion of the air guide component from the top surface of the heating chamber. 4. The heating cooker according to any one of claims 1 to 3, wherein, The heating cooker also includes a hot air circulation heating unit, which includes a heat source for circulating hot air to heat the object housed in the heating chamber. The circulating fan and the flow path forming part in the heating chamber are included in the hot air circulating heating part. 5. The heating cooker according to any one of claims 1 to 3, wherein, The internal temperature sensor is configured to function as a detector for detecting "dry burning" during microwave heating. 6. The heating cooker according to any one of claims 1 to 3, wherein, The heating cooker also includes a radiant heating element, which comprises a heat source that radiates heat to the object being heated and housed in the heating chamber. The temperature sensor inside the chamber is positioned directly above the heat source of the radiant heating element, which is located near the top surface of the heating chamber.