EP1793171A1

EP1793171A1 - Heating cooking apparatus

Info

Publication number: EP1793171A1
Application number: EP05728923A
Authority: EP
Inventors: Yukishige Shiraichi; Mitsuo Ohuchi; Rika Nozawa
Original assignee: Sharp Corp
Current assignee: Sharp Corp
Priority date: 2004-08-31
Filing date: 2005-04-11
Publication date: 2007-06-06
Also published as: RU2007111953A; WO2006025133A1

Abstract

There is provided a heating cooker (1, 2) capable of heating cooking an object to be heated without causing unevenness. The heating cooker (1, 2) includes an air blower (20) for blowing air in a predetermined flow direction, and a heating room (12) having a wall face (32) for housing the object (S) to be heated. Outlets (18a, 18b, 18c, 18d) for blowing air sent from the air blower (20) are formed in the wall face (32) of the heating room (12), and air-flow intercepting walls for intercepting air flows are formed and positioned in the flow direction side with respect to the outlets (18a, 18b, 18c, 18d). The air-flow intercepting walls include air-direction changeable members (50a, 50b, 50c, 50d) for changing air flows which are blown from the outlets (18a, 18b, 18c, 18d), the air-direction changeable members (50a, 50b, 50c, 50d) being positioned at the end portions of the outlets (18a, 18b, 18c, 18d) in the flow direction side.

Description

TECHNICAL FIELD

The present invention generally relates to a heating cooker and, more particularly, to a heating cooker capable of uniformly heating and cooking foodstuffs as objects to be heated.

BACKGROUND ART

A conventional heating cooker such as a convection oven includes a fan for forcibly circulating hot air within a heating room. The conventional heating cooker circulates the hot air within the heating room with the fan to increase a cooking speed and uniformize temperature distribution within the heating room for improving baking performance.
A heating cooker has, depending on a model, an oven cooking function, an electromagnetic-wave heating cooking function, a dielectric-heating cooking function, a steam cooking function or at least two cooking functions selected from these cooking functions.
Fig. 16 is a front view illustrating a conventional heating cooker. Fig. 17 is a view illustrating directions of air flows caused by a centrifugal fan within an air blower. Fig. 18 is a view illustrating heating distribution near a surface of a mount plate placed on an upper stage of the conventional heating cooker. Fig. 19 is a view illustrating directions of air flows within a heating room of the conventional heating cooker.
As shown in Fig. 16, a conventional heating cooker 3 is provided with a heat-insulated box body 11, a heating room 12 which is provided in the box body 11 to cook therein an object to be heated, a heat-insulating door 15 which freely opens/closes a front opening of the heating room 12, a heater 13 for generating hot air, an air blower 20, an operation unit 16 by which a user inputs commands, and a controller (not shown) which controls the heater 13 and the air blower 20. Herein, the object to be heated is a unit of a matter to be cooked.
The heating room 12 has right and left side walls 31, a back wall 32, a top wall 33 and a bottom wall 34. The air blower 20 is provided at a back side of the back wall 32. Supporting portions 19 for attachably/detachably supporting mount plates 40a and 40b are formed on the side walls 31 at upper and lower portions thereof. In the back wall 32, an inlet 17 and outlets 18a to 18d each of which consists of a plurality of holes are formed. The inlet 17 is placed at the center of the back wall 32.
The outlets are constituted by the first outlet 18a, the second outlet 18b, the third outlet 18c and the fourth outlet 18d. The first outlet 18a is placed above the upper mount plate 40a and is formed into a band shape along longer sides of the back wall 32. The second outlet 18b and the fourth outlet 18d are placed at an intermediate position between the upper mount plate 40a and the lower mount plate 40b and in the vicinity of the right and left side walls 31. The second outlet 18b and the fourth outlet 18d are formed from a plurality of holes arranged in a circular shape with a small region. The third outlet 18c is placed below the lower mount plate 40b and is formed into a band shape along the longer sides of the back wall 32.
As shown in Figs. 16 and 17, the air blower 20 includes a centrifugal fan 22, a driving motor (not shown) for rotating and driving the centrifugal fan 22 in a direction shown by arrows, and a fan casing 21 which pivotally supports the centrifugal fan 22. An inlet of the centrifugal fan 22 faces the inlet 17. The annular heater 13 such as a sheathed heater is placed around the centrifugal fan 22. The fan casing 21 covers the back side of the back wall 32 to form a space surrounding the centrifugal fan 22 and the heater 13.
In Fig. 17, when the fan casing 21 is viewed from the front side, D indicates a first corner positioned at an upper left portion in the fan casing 21, E indicates a second corner positioned at an upper right portion in the fan casing 21, F indicates a third corner positioned at a lower right portion in the fan casing 21, and G indicates a fourth corner positioned at a lower left portion in the fan casing 21.
In the heating cooker 3 configured as described above, the mount plate 40a on which an object to be heated is mounted is placed into the heating room 12. When the content of cooking is input through the operation unit 16, the controller drives and controls the heater 13, the air blower 20 and the like on the basis of the commands input from the operation unit 16, to start heating and cooking of the object to be heated.
Air blown from the centrifugal fan 22 is heated by the heater 13 within the fan casing 21 to be hot air. The hot air is blown from the outlets 18a to 18d. The hot air blown from the outlets 18a to 18d flows toward the front face of the heating room 12, impinges to the door 15 to change its flow direction, is concentrated at the center, and then is drawn into the fan casing 21 through the inlet 17 by a drawing force of the air blower 20.
Within the fan casing 21, as shown by solid-line arrows I in Fig. 17 arid broken-line arrows I in Fig. 19, air is spirally flowed toward the four corners D to G of the fan casing 21 by a centrifugal force of rotation, while being along a rotation direction of the centrifugal fan 22 (a clockwise direction). Consequently, for example, in the case where the outlet is formed into a band shape along the longer sides of the back wall 32 as the first outlet 18a and the third outlet 18c, as shown in Fig. 19, air is blown into the heating room 12 by spiral air flows within the fan casing 21. The air blown into the heating room 12 flows toward the door 15 along the side walls 31, the top wall 33 and the bottom wall 34. Heat is accumulated at the side wall 31 in the flow direction side along the rotation direction of the centrifugal fan 22, namely, at a downstream side of flows, thereby resulting in uneven temperature distribution within the heating room 12.
Consequently, for example, there will be induced heating distribution on the upper mount plate 40a in which excessively-heated portions are spread in the object to be heated S in the vicinity of the side wall 31 in the flow direction side, as shown in Fig. 18. Further, such heating distribution will be also induced below the lower mount plate 40.
A possible reason for the occurrence of such uneven heating distribution (heating unevenness) is the biased air flows caused by spiral air flows specific to the centrifugal fan 22. The air is blown into the heating room 12 while being biased toward the flow direction side, as shown by the solid-line arrows H in Fig. 19.
Further, there will also be uneven heating distribution (heating unevenness) in the opposite side from the flow direction side, which is induced by the following reason, even though it does not cause improper baking conditions.
Within the fan casing 21, air is spirally flowed toward the four corners D to G of the fan casing 21 as shown by the solid-line arrows I in Fig. 17. These spiral air flows are blown out from the four corners D to G of the fan casing 21 having the effect of guiding flows into the heating room 12. Consequently, a greater quantity of air is blown from the four corners D to G of the fan casing 21 than from the outlets provided at the intermediate positions between the four corners D to G. Namely, there will be differences in the quantity of blown air at the outlet at the first corner D and the outlet provided at the intermediate position between the first corner D and the second corner E, thus resulting in heating unevenness in the object to be heated which is housed within the heating room 12.
Furthermore, hot air blown into the heating room 12 from the outlets 18a to 18d causes flows along the rotation direction of the centrifugal fan 22 due to influences of the spiral air flows. Namely, air blown from the outlet at the second corner E is flowed along the side wall 31 in flow direction side due to spiral flows, and thus hot air is concentrated at the side wall 31 in the flow direction side on the upper mount plate 40a. This results in heating unevenness in the object to be heated which is housed within the heating room 12.
Therefore, Japanese Examined Patent Publication No. 7-111256 (Patent Literature 1) discloses a heating cooker provided with a wind-direction plate within an air blower for restricting air flows, in order to improve heating unevenness in a rotation direction of a centrifugal fan, which is caused by spiral air flows which are specific to the centrifugal fan.
Japanese Unexamined Patent Publication No. 2003-168551 (Patent Literature 2) discloses a heating cooker having a high-frequency heating device or a controller placed under a heating room to increase a volume of the heating room in a lateral-width direction. This can increase a dimension of a mount plate in the lateral-width direction, thus enabling selecting a mounting position depending on an object to be heated which is intended to be heated and cooked. This can overcome baking unevenness.
Furthermore, in the conventional heating cooker, the difference between the quantity of air blown from the outlet at the first corner D and the quantity of air blown from the outlet provided at the intermediate position between the first corner D and the second corner E will cause high-temperature portions at the center of the heating room 12.
Further, hot air blown from the centrifugal fan 22 is concentrated and compressed at the four corners D to G of the fan casing 21. Thus, air blown from the four corners D to G of the fan casing 21 will be blown at a larger velocity than air blown from the outlets provided at the intermediate positions between the four corners D to G. Consequently, for example, hot air blown from the outlet at the first corner D will flow toward the door 15 near the side wall 31 at the opposite side from the flow-destination side on the upper mount plate 40a without abiding at the side of the back wall 32. This results in portions which are not heated or insufficiently-heated portions at the side of the back wall 32 and high-temperature portions at the side of the door 15 on the upper mount plate 40a, as shown in Fig. 18.
Therefore, Japanese Unexamined Patent Publication No. 63-14016 (Patent Literature 3) discloses a heating cooker in which an opening area of an outlet is inversely varied in accordance with a quantity of air, along a end portion of the outlet which generates a large quantity of air by the rotation of a centrifugal fan and along a end portion of the outlet which generate a small quantity of air, in order to uniformize a heating temperature within a heating room.
Japanese Unexamined Patent Publication No. 2004-93092 (Patent Literature 4) discloses a heating cooker including a heater (sheathed heater) which is double-wound around a hot-air fan 18 and also shaped to have at least a single-wound portion even between respective heater end portions to be outwardly drawn, in order to uniformize a heating temperature within a heating room.
Patent Literature 1: Japanese Examined Patent Publication No. 7-11256
Patent Literature 2: Japanese Unexamined Patent Publication No. 2003-168551
Patent Literature 3: Japanese Unexamined Patent Publication No. 63-14016
Patent Literature 4: Japanese Unexamined Patent Publication No. 2004-93092

DISCLOSURE OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

Japanese Examined Patent Publication No. 7-11256 improves the bias of blown air caused by spiral air flows which are specific to a centrifugal fan by providing air-direction plates within an air blower. However, heating unevenness in a direction toward a door can not be alleviated by simply installing the air-direction plates. In general, when an object which intercepts natural air flows such as an air-direction plate is installed, this increase the resistance to blown air, thus reducing the quantity of air blown from the outlet. Thus, a traveling distance of air proceeding toward the door is reduced in the heating room. This weakens the heating of objects to be heated which are placed apart from the outlets, in comparison with objects to be heated which are placed in the vicinity of the outlets. Consequently, further consideration of the air-direction plates must be made, or otherwise there will still exist the problem of heating unevenness in the direction toward the door.
Further, according to Japanese Unexamined Patent Publication No. 2003-168551 , the height-wise dimension is made greater than the lateral-width-wise dimension, and thus end faces of the air blower at the top-wall side and the bottom-wall side are extended in the lateral-width direction. This facilitates spiral air flows at the extended end faces, thus causing the direction of air blown from the outlets to be further oriented along the rotation direction of the centrifugal fan. This makes it difficult to flow air toward the door of the heating room. Furthermore, since the outlets are further separated from the outer perimeter of the centrifugal fan, there is the problem of reduction of air blown from the outlets.
In Japanese Unexamined Patent Publication No. 63-14016 , the opening area of the outlets is varied to adjust the quantity of air blown from the outlets. However, such a shape can achieve only the adjustment of the quantity of air in the lateral-width-wise direction of the heating room, and can not alleviate the heating unevenness as shown in Fig. 18.
In Japanese Unexamined Patent Publication No. 2004-93092 , the quantity of air blown from the outlets is adjusted by utilizing a portion of the heater. However, this is not preferable in terms of the heat efficiency, since the shape of the heater is restricted in order to alleviate the bias of air blows. This may induce heating unevenness depending on the shape of the heater.
Therefore, it is an object of the present invention to provide a heating cooker capable of uniformly heating and cooking an object to be heated without causing unevenness.
It is another object of the present invention to provide a heating cooker capable of uniformly heating and cooking an object to be heated without causing unevenness, by guiding air flows toward a door within a heating room.
It is still another object of the present invention to provide a heating cooker capable of uniformly heating and cooking an object to be heated without causing unevenness, by preventing bias of air flows within a heating room.

MEANS FOR SOLVING THE PROBLEMS

A heating cooker according to the present invention includes an air blower for blowing air in a predetermined flow direction, and a heating room having a wall face for housing an object to be heated. Outlets for blowing air sent from the air blower are formed in the wall faces of the heating room. Air-flow intercepting walls for intercepting air flows are formed to be positioned in the flow direction side with respect to the outlets.
With the heating cooker according to the present invention, the air-flow intercepting walls for intercepting air flows are positioned in the flow direction side with respect to the outlets and therefore air is blown from the outlets while impinging on the air-flow intercepting walls. Air blown from the outlets will not be accumulated at the wall face at the flow direction side and thus air blown into the heating room will be uniformly spread, thus preventing occurrence of heating unevenness in the object to be heated.
With the heating cooker according to the present invention, since the air-flow intercepting walls for intercepting air flows are positioned in the flow direction side with respect to the outlets, air is blown into the heating room through the outlets positioned in the opposite side from the flow direction side, and air will not be blown from the flow direction side into the heating room. Consequently, even if air blown from the opposite side from the flow direction side reaches the wall face at the flow direction side within the heating room due to air flows caused by the air blower, air will not be accumulated and air blown into the heating room will be uniformly spread, thus preventing occurrence of heating unevenness in the object to be heated.
With a heating cooker according to an aspect of the present invention, preferably, the air-flow intercepting walls may include air-direction changeable members for changing air flows which are blown from the outlets and the air-direction changeable members are positioned at the end portions of the outlets in the flow direction side.
In this case, air changes its flow direction on impinging on the air-direction changeable members and then is blown from the outlets. The air blown from the outlets flows toward the front side of the heating room, namely toward the door. Consequently, air will not be accumulated at the wall face at the flow direction side, and therefore air blown into the heating room will be uniformly spread, thus preventing occurrence of heating unevenness in the object to be heated.
With a heating cooker according to an aspect of the present invention, preferably, the outlets are formed at the region extending from the end portion of the wall face of the heating room in the opposite side from said flow direction side to the proximity of the middle portion of the wall face.
In this case, air is blown into the heating room from the outlets positioned in the opposite side from the flow direction side, and there is no air blown into the heating room from the flow direction side. Consequently, even if air blown from the opposite side from the flow direction side reaches the wall face at the flow direction side within the heating room due to air flows caused by the air blower, air will not be accumulated and air blown into the heating room will be uniformly spread, thus avoiding concentration of heat at the wall face in the flow direction side within the heating room. Further, since the flow direction of air which is blown from the outlets are changed by the air-direction changeable members, air will be evenly spread to the door. This can uniformize the temperature distribution within the heating room.
Further, with a heating cooker according to an aspect of the present invention, preferably, the air blower includes a centrifugal fan. Preferably, the centrifugal fan is placed to face the middle portion of the wall face of the heating room. Preferably, the air-direction changeable members are positioned within the region between two parallel lines passing through the most flow direction side point and the most counter flow direction side point on the outer circle defined by the centrifugal fan.
In this case, the direction of air proceeding toward the flow direction side can be changed by the air-direction changeable members and thus air with a large air velocity can be blown into the heating room. This can increase the traveling distance of air proceeding toward the door of the heating room.
In the aforementioned preferable heating cooker, preferably, the outlets are formed at an upper portion, an intermediate portion and a lower portion of the wall face of the heating room and the outlets formed at the intermediate portion of the wall face of the heating room are placed at the both sides of the centrifugal fan.
In this case, air can be blown from the upper portion, the intermediate portion and the lower portion of the heating room, thus providing a more uniform temperature within the heating room.
With a heating cooker according to an aspect of the present invention, preferably, the air-direction changeable members are placed such that they extend from near the outer perimeter of the wall face of the heating room toward the center thereof in the proximity of the edge of the wall face of the heating room.
In the aforementioned preferable heating cooker, more preferably, the air-direction changeable members are placed such that they are inclined with respect to the flow direction.
In the aforementioned preferable heating cooker, more preferably, the end portions of the air-direction changeable members near the outer perimeter of the wall face of the heating room are positioned in the flow direction side and the end portions of the air-direction changeable members near the center of the wall face of the heating room are positioned in the opposite side from the flow direction side.
In this case, the air-direction changeable members will not steeply guide air flows toward the opposite side from the flow direction side to intercept air. This can prevent extreme concentrations of hot air at the end portion of the outlets in the flow direction side, and a part of the blown air can be flowed to the flow direction side. There will be no occurrence of high-temperature portions near the end portion of the outlets in the flow direction side and also there will be no occurrence of low-temperature portions in the flow direction side, which can alleviate heating unevenness in the object to be heated.
With a heating cooker according to another aspect of the present invention, preferably, the wall face of the heating room includes closed regions including no outlets formed therein and blowoff regions including the outlets formed therein. Preferably, the closed regions include the air-flow intercepting walls positioned in the flow direction side of the wall face of the heating room and the blowoff regions include the outlets positioned in the opposite side from the flow direction side of the wall face of the heating room.
In this case, air can be blown into the heating room from the outlets in the opposite side, and there is no air blown into the heating room from the flow direction side. Consequently, air blown from the opposite side will reach the wall face at the flow direction side due to air flows from the air blower, and air will be evenly spread in the width-wise direction of the heating room. This can prevent heat accumulation at the wall face in the flow direction side, thus uniformizing the heating condition within the heating room.
With a heating cooker according to another aspect of the present invention, preferably, the blowoff regions are biased toward the opposite side from the flow direction side of the wall face of the heating room.
With a heating cooker according to another aspect of the present invention, preferably, the wall face of the heating room is constituted by a first region in the flow direction side and a second region in the opposite side from the flow direction side and the blowoff regions include a part of the first region.
In this case, air is not blown into the heating room from the flow direction side and hot air is not concentrated in the flow direction side within the heating room more than necessary, thus preventing heat accumulation in the vicinity of the side wall in the flow direction side.
With a heating cooker according to another aspect of the present invention, preferably, plural mount plates on which the object to be heated is mounted are placed within the heating room at upper and lower positions and the blowoff regions are placed at a position above the mount plate placed at the uppermost stage and at a position below the mount plate placed at the lowermost stage.
In this case, air from the air blower is not blown out from the flow direction side at a position above the mount plate placed at the uppermost stage or a position below the mount plate placed at the lowermost stage.
With a heating cooker according to another aspect of the present invention, preferably, the blowoff regions are formed to have an opening area which gradually decreases toward the opposite side from the flow direction side.
With a heating cooker according to another aspect of the present invention, preferably, the heating room includes a rectangular wall face, when the height of the wall face of the heating room is defined as T, the width is defined as W and the height-to-width ratio is defined as P = T/W, P is 0.7 or less, and as to the straight line connecting the upper end and the lower end of the end portion of the blowoff regions at the opposite side from the flow direction side, when the height from the upper end to the lower end is defined as t, the width thereof in the width-wise direction of the wall face of the heating room is defined as w and the inclination thereof is defined as p = t/w, P is equal to or greater than p.
In this case, at the end portion of the blowoff region at the opposite side, air is concentrated to the opposite side by air flows from the air blower and the air is blown therefrom. However, at the end portion of the blowoff region at the opposite side, the edge is formed to have the aforementioned inclination p, and therefore all the air concentrated at the opposite side will not be blown out. Consequently, air which has not been blown out can be efficiently directed to the flow direction side. This eliminates the difference in the quantity of blown air over the region from the opposite side to the flow direction side of the outlets, thus preventing concentration of air at the middle portion of the heating room.
Further, since the edge is formed to have the aforementioned inclination p at the end portion of the blowoff region in the opposite side, there is no air blown from the portion which could blow air with a largest velocity. Namely, air is blown from more counter-flow direction outlets than the portion which could blow air with a largest velocity. Consequently, air is blown from the outlets with substantially the same blowing velocity, at the end portion in the opposite side, the middle portion and the end portion in the flow direction side. This can equalize the traveling distances of air within the heating room to send uniform air into the heating room, thus alleviating heating unevenness in the object to be heated.
With a heating cooker according to the present invention, the heating room includes a rectangular wall face, and the outlets are formed along the horizontal edge of the rectangular shape defined by the wall face.
With the aforementioned preferable heating cooker, when the height of the wall face of the heating room is defined as T, the width is defined as W and the height-to-width ratio is defined as P = T/W, P is 0,7 or less.
This can reduce air concentrated at the corners positioned at the flow direction side along the longer sides of the wall face of the heating room which are the horizontal edges thereof and in the opposite side along the shorter sides of the wall face of the heating room which are the vertical edges thereof. This can eliminate the difference in the quantity of blown air between the opposite side and the flow direction side of the outlets, thereby uniformizing the temperature distribution, or the heating condition, within the heating room.

EFFECTS OF THE INVENTION

The present invention enables heating and cooking foodstuffs as objects to be heated, without causing heating unevenness therein.
According to an aspect of the present invention, it is possible to ensure air velocities which can provide sufficient traveling distances of air blown from the outlets in the depth-wise direction and also prevent partial concentration of air in the lateral-width-wise direction of the heating room, with the relationship between the positions of the outlets in the wall face of the heating room and the air-direction changeable members provided in the flow direction side with respect to the positions of the outlets. By creating such air flows within the heating room, it is possible to maintain the uniformity of the temperature distribution in the lateral-width-wise direction within the heating room and also prevent the nonuniformity of the temperature distribution in the depth-wise direction within the heating room, thus eliminating heating unevenness in the object to be heated.
According to another aspect of the present invention, since the outlets are provided in the opposite side from the flow direction side, air is not blown into the heating room from the flow direction side, thus preventing heat accumulation in the vicinity of the wall face in the flow direction side. Consequently, air blown from the outlets provided in the wall face is sent without being biased in the lateral-width-wise direction and in the depth-wise direction within the heating room, and air is evenly impinged on the object to be heated on the mount plate, thus enabling heating cooking without causing heating unevenness.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a front view illustrating a heating cooker according to an embodiment of the present invention.
Fig. 2 is a side cross sectional view illustrating the heating cooker according to the embodiment of the present invention.
Fig. 3 is a view illustrating a centrifugal fan in the heating cooker according to the embodiment of the present invention, which is viewed from a back wall.
Fig. 4 is a view illustrating the back wall in the heating cooker according to the embodiment of the present invention, which is viewed from a fan casing.
Fig. 5 is a view illustrating the directions of blown air in the heating cooker according to the embodiment of the present invention.
Fig. 6 is a view illustrating, in detail, the outlets in the heating cooker according to the embodiment of the present invention.
Figs. 7(a) to 7(f) are views illustrating the temperature distributions near a surface of an upper mount plate for respective different positions of a first air-direction changeable member in the heating cooker according to the embodiment of the present invention.
Figs. 8(a) to 8(f) are views illustrating the temperature distributions near the surface of the upper mount plate for respective different height-to-width ratios (P = T/W) of the wall face of the heating room in the heating cooker according to the embodiment of the present invention.
Fig. 9 is a front view illustrating a heating cooker according to another embodiment of the present invention.
Fig. 10 is a side cross sectional view illustrating the heating cooker according to another embodiment of the present invention.
Fig. 11 is a front view illustrating directions of air flows in the heating cooker according to another embodiment of the present invention.
Fig. 12 is a view illustrating temperature distribution near a surface of an upper mount plate in the heating cooker according to another embodiment of the present invention.
Fig. 13 is a view illustrating, in detail, outlets in the heating cooker according to another embodiment of the present invention.
Figs. 14(a) to 14(e) are views illustrating the temperature distributions near the surface of the upper mount plate for respective different positions of the outlets end portion in the flow direction side in the heating cooker according to another embodiment of the present invention.
Fig. 15 is a view illustrating the temperature distributions near the surface of the upper mount plate for respective different height-to-width ratios (P = T/W) of the wall face of the heating room and for respective different inclinations (p = t/w) of the shape of the end portion of the outlets in the opposite side in the heating cooker according to another embodiment of the present invention.
Fig. 16 is a front view illustrating a conventional heating cooker.
Fig. 17 is a view illustrating air flows of a centrifugal fan in the conventional heating cooker.
Fig. 18 is a view illustrating temperature distribution near a surface of an upper mount plate in the conventional heating cooker.
Fig. 19 is a view illustrating directions of blown air in the conventional heating cooker.

EXPLANATION OF SYMBOLS

1, 2: heating cooker, 12: heating room, 18a: first outlet, 18b: second outlet, 18c: third outlet, 18d: fourth outlet, 20: air blower, 22: centrifugal fan, 31: side wall, 32: back wall, 33: top wall, 34: bottom wall, 40a: upper mount plate, 40b: lower mount plate, 50a: first air-direction changeable member, 50b: second air-direction changeable member, 50c: third air-direction changeable member, 50d: fourth air-direction changeable member, S: object to be heated

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, one embodiment of the present invention will be described on the basis of the drawings. Fig. 1 is a front view illustrating a heating cooker according to one embodiment of the present invention. Fig. 2 is a side cross sectional view illustrating the heating cooker along with the directions of air flows (arrows). Fig. 3 is a view illustrating a centrifugal fan from a back wall side. Fig. 4 is a view illustrating the back wall viewed from a fan casing side. Fig. 5 is a view illustrating directions of air flows within the heating cooker.
As shown in Figs. 1 and 2, a heating cooker 1 according to the present invention includes a heat-insulated box body 11 which is opened at the front face, a heating room 12 provided within the box body 11 for housing an object to be heated S, a heater 13 for heating the object to be heated S, an air blower 20 for blowing hot air heated by the heater 13 and a controller (not shown) for controlling the heater 13 and the air blower 20.
A heat-insulation door 15 is provided at the front side of the box body 11 such that it can be freely opened and closed, and there is provided an operation unit 16 for inputting commands from a user. The controller, which is constituted by microcomputers, controls the air blower 30, the heater 13 or the like on the basis of commands input from the operation unit 16.
The heating room 12 has two side walls 31, a back wall 32, a top wall 33 and a bottom wall 34. A fan casing 21 for the air blower 20 is mounted on the back side of the back wall 32. On the right and left side walls 31, upper and lower supporting portions 19 for supporting mount plates 40a and 40b are formed such that they protrude therefrom at two stages. The mount plates 40a and 40b are constituted by a plate-shaped mounting portion having an area equivalent to the horizontal cross section of the heating room 12 in order to enable mounting the object to be heated S thereon and a flange-shaped edge portion formed around the mounting portion. Since the edge portions of the mount plates 40a and 40b are supported by the supporting portions 19, the mount plates 40a and 40b are housed within the heating room 12. The mount plate to be mounted at an upper portion is referred to as an upper mount plate 40a and the mount plate to be mounted at a lower portion is referred to as a lower mount plate 40b.
The air blower 20 is constituted by a centrifugal fan 22 and a motor 23 for rotating and driving the centrifugal fan 22 as shown by arrows in Figs. 1 and 3. The centrifugal fan 22 is rotatably supported to the fan casing 21 and placed such that it faces the back wall 32. The rotation shaft of the centrifugal fan 22 is positioned at the center of the back wall 32. The heater 13 is concentrically placed about the centrifugal fan 22. The fan casing 21 includes two side surfaces 21a, a back surface 21b, a top surface 21c and a bottom surface 21d, as shown in Fig. 3.
As shown in Fig. 5, since the centrifugal fan 22 rotates in the clockwise direction as shown by arrows, hot air is centrifugally blown from the centrifugal fan 22. This creates hot air flows proceeding outwardly as shown by broken-line arrows B, along the direction of the rotation of the centrifugal fan 22.
In the back wall 32, there are formed an inlet 17 for drawing air from the heating room 12 into the fan casing 21 and outlets 18a to 18d for blowing hot air heated by the heater 13 into the heating room 12. The inlet 17 is placed at the center of the back wall 32 and faces the inlet of the centrifugal fan 22. The inlet 17 is formed from plural holes so as to have a circular shape.
The outlets 18a to 18d are formed from a plurality of holes which are gathered together and have a diameter of about 5 mm. By forming the outlets 18a to 18d from plural gathered holes with a punched-hole shape, there may be provided effects of preventing leakage of electromagnetic waves to the outside of the heating room 12 in the case of concurrently utilizing electromagnetic-wave heating and also effects of preventing a person from suffering from incised wounds and the like, when he inserts his fingertip into the holes in cleaning the inside of the heating room 12.
The outlets 18a to 18d are constituted by the upper first outlet 18a, the second outlet 18b and the fourth outlet 18d at intermediate positions and the lower third outlet 18c. The first outlet 18a is placed above the upper mount plate 40a and formed to have a band shape along the longer sides of the back wall 32 which are the horizontal edges thereof. The second outlet 18b is placed at an intermediate position between the upper mount plate 40a and the lower mount plate 40b and in the vicinity of the right side wall 31 when the heating room 12 is viewed from the front side and formed to be a round shape with a small region. The third outlet 18c is placed below the lower mount plate 40b and formed to be a band shape along the longer sides of the back wall 32. The fourth outlet 18d is placed at an intermediate position between the upper mount plate 40a and the lower mount plate 40b and in the vicinity of the left side wall 31 when the heating room 12 is viewed from the front side and are formed to be a round shape with a small region. The second outlet 18b and the fourth outlet 18d are symmetrically placed with respect to the inlet 17 such that they sandwich the inlet 17.
The first outlet 18a and the third outlet 18c are formed from plural rows of holes which are evenly spaced apart from one another along the longer sides of the back wall 32 and have substantially a rectangular shape. The first outlet 18a is formed to have an opening area which gradually decreases toward the hot-air-flow direction side. Namely, near the end portion of the first outlet 18a in the flow direction side, the number of vertically-arranged punched holes decreases from three to two and one in the flow direction direction, and therefore the opening area of the first outlet 18a gradually decreases toward the flow direction side. Near the end portion of the first outlet 18a in the flow direction side, the edge thereof defined by the arranged punched holes, in the flow direction side, is inclined along the direction of flow. There is not formed more flow direction outlet than the edge of the first outlet 18a defined by the arranged punched holes in the flow direction side.
Here, "the flow direction side" means the side toward which the centrifugal fan 22 rotates or the downstream side of air flows caused by the centrifugal fan 22, and "the opposite side from the flow direction side" means the opposite side from the side toward which the centrifugal fan 22 rotates, or the upstream side of air flows caused by the centrifugal fan 22. In the present embodiment, at an upper portion of the heating room 12 such as a region above the upper mount plate 40a, the flow direction side corresponds to the right-half side of the heating room 12 when the heating room 12 is viewed from the front side and the opposite side corresponds to the left-half side thereof. At a lower portion of the heating room 12 such as a region below the lower mount plate 40b, the flow direction side corresponds to the left-half side of the heating room 12 when the heating room 12 is viewed from the front side and the opposite side corresponds to the right-half side thereof. At an intermediate portion of the heating room 12 such as the region between the upper mount plate 40a and the lower mount plate 40b, on the right of the centrifugal fan 22, the flow direction side corresponds to the lower-half side of the heating room 12 when the heating room 12 is viewed from the front side and the opposite side corresponds to the upper-half side thereof, while on the left of the centrifugal fan 22 the flow direction side corresponds to the upper-half side and the opposite side corresponds to the lower-half side.
The end portion of the first blowing openings 18a in the flow direction side is positioned between the vertical straight line passing through the most flow direction side point on the outer circle defined by the centrifugal fan 22 and the vertical straight line passing through the most counter flow direction side point on the outer circle defined by the centrifugal fan 22. The end portion of the first outlet 18a at the opposite side is positioned in the vicinity of the side wall 31 in the opposite side. As shown in Fig. 6, the end portion of the first outlet 18a in the flow direction side is positioned within the region between the two vertical straight lines L passing through the most flow direction side point and the most counter flow direction side point on the outer circle defined by the centrifugal fan 22. Consequently, there will be no air blown from the flow direction side into the heating room 12 and hot air will not be concentrated at the flow direction side within the heating room 12 more than necessary, thereby preventing heat accumulation in the vicinity of the side wall 31 at the flow direction side.
The third outlet 18c is placed at the position which is rotationally displaced by 180 degrees from the first outlet 18a about the center shaft of the centrifugal fan 22, namely the center of the back wall 32, and is formed to have a shape similar to that of the first outlet 18a. Further, the end portion of the third outlet 18c in the flow direction side is positioned between the vertical straight line passing through the most flow direction side point on the outer circle defined by the centrifugal fan 22 and the vertical straight line passing through the most counter flow direction side point on the outer circle defined by the centrifugal fan 22. As shown in Fig. 6, the end portion of the third outlet 18c in the flow direction side is positioned within the region between the two vertical straight lines L passing through the most flow direction side point and the most counter flow direction side point on the outer circle defined by the centrifugal fan 22. The end portion of the third outlet 18c in the opposite side is positioned in the vicinity of the side wall 31 in the opposite side.
As shown in Fig. 4, as an embodiment of air-flow intercepting walls, there are provided air-direction changeable members 50a to 50d for changing the directions of air flows, at the end portions of the respective outlets 18a to 18d in the flow direction side. The respective air-direction changeable members 50a to 50d are placed on the back side of the back wall 32, namely within the fan casing 21. The air-direction changeable members are constituted by the first air-direction changeable member 50a, the second air-direction changeable member 50b, the third air-direction changeable member 50c and the fourth air-direction changeable member 50d. Each of the air-direction changeable members 50a to 50d is formed from a metal plate or the like, which is folded at a right angle into an L-shape. The air-direction changeable members 50a to 50d have press-contact portions 51 pressure-bonded to the back wall 32 through adhesive or welding so that the air-direction changeable members 50a to 50d are secured thereto. The guide surfaces 52 of the air-direction changeable members 50a to 50d to which hot air will impinge are positioned such that they are substantially perpendicular to the back wall 32. The arrows shown in Fig. 4 indicate the direction of rotation of the centrifugal fan.
The first air-direction changeable member 50a is provided along the hypotenuse connecting the uppermost vertex and the lowermost vertex of the end portion of the first outlet 18a at the flow direction side. The upper side of the first air-direction changeable member 50a is proximal to the top surface 21c within the fan casing 21 and the rear side of the first air-direction changeable member 50a is proximal to the back surface 21b within the fan casing 21.
Namely, the first air-direction changeable member 50a is inclined with respect to the direction of air flows. The first air-direction changeable member 50a is installed such that the end portion of the first air-direction changeable member 50a near the top surface 21c (the outer end portion) is positioned in the flow direction side and the end portion thereof near the center is positioned in the opposite side.
The second air-direction changeable member 50b is provided at the end portion of the second outlet 18b in the flow direction side. Further, the second air-direction changeable member 50b is positioned such that it is substantially parallel with the longer sides of the wall face of heating room 12 and also is substantially perpendicular to the shorter sides of the wall face of the heating room 12. The second air-direction changeable member 50b is proximal to a side surface 21a within the fan casing 21 and also is proximal to the back surface 21b within the fan casing 21. The second air-direction changeable member 50b is formed to have a lateral width greater than the lateral width of the second outlet 18b. The fourth air-direction changeable member 50d has the same shape as that of the second air-direction changeable member 50b and is placed such that the second and fourth wind- direction changing members 50d and 50b are point-symmetry with respect to the center of the centrifugal fan 22.
The third air-direction changeable member 50c is provided along the hypotenuse connecting the uppermost vertex and the lowermost vertex of the end portion of the third outlet 18c in the flow direction side. The lower side of the third air-direction changeable member 50c is proximal to the bottom surface 21d within the fan casing 21 and the rear side of the third air-direction changeable member 50c is proximal to the back surface 21b within the fan casing 21.
In the heating cooker 1 configured as described above, the centrifugal fan 22 creates circumferentially-flowing hot air. The hot air flowing within the fan casing 21 as shown by broken-line arrows B is blown into the heating room 12 through the outlets 18a to 18d, as shown by solid-line arrows A in Fig. 5. Even when the mount plate 40a and 40b is mounted on the upper or lower stage, hot air passes over the surface and the bottom surface of the mount plate 40a and 40b. In Fig. 5, the solid-line arrows A indicate hot air flows within the heating room 12 and the broken-line arrows B indicate hot air flows within the air blower 20.
The first air-direction changeable member 50a formed at the end portion of the first outlet 18a in the flow direction side intercepts hot air flowing toward the second corner E of the fan casing 21. The hot air impinged on the first air-direction changeable member 50a is subjected to forces of circumferential flow components generated by the centrifugal fan 22 and is blown into the heating room 12 through the first outlet 18a diagonally forward toward the flow direction side. Namely, hot air is blown from the end portion of the first blowing openings 18a in the flow direction side with a greater velocity than when there is no air-direction changeable member.
The hot air flows toward the door 15 of the heating room 12. Furthermore, since the first outlet 18a are not formed up to the vicinity of the side wall 31 at the flow direction side, the hot air blown from the first outlet 18a will not be concentrated at the flow direction side above the upper mount plate 40a. Consequently, air will not be accumulated at the side wall 31 in the flow direction side and hot air blown into the heating room 12 will be uniformly spread, thereby alleviating heating unevenness in the object to be heated S.
Further, since the first air-direction changeable member 50a is inclined with respect to the direction of air flows, hot air flows will not be steeply guided toward the opposite side and thus will not be intercepted. Therefore, extreme concentration of hot air will not occur at the end portion of the first outlet 18a in the flow direction side. Some hot air can be fed to the flow direction side. Hot air blown from the end portion of the first outlet 18a in the flow direction side also flows toward the flow direction side, thus causing flows proceeding toward the side wall 31 along the back wall 32. There will be no occurrence of high-temperature portions near the end portion of the first outlet 18a in the flow direction side and also there will be no occurrence of low-temperature portions in the flow direction side, which can alleviate heating unevenness in the object to be heated.
Further, the first air-direction changeable member 50a is provided proximally to the top surface 21c and the back surface 21b in the fan casing 21. Hot air is directed toward the outer perimeter of the fan casing 21 by the centrifugal fan 22, and hot air can be efficiently collected and guided into the heating room 12 by virtue of the existence of the first wind-direction changing member 50a. Furthermore, since the first air-direction changeable member 50a is in intimate contact with the back wall 32, there will no leakage of hot air through between the first air-direction changeable member 50a and the back wall 32. Consequently, hot air can be collected without wasting it, and therefore the quantity of hot air blown from the first outlet 18a can be increased as much as possible. By combination of these effects provided by the first air-direction changeable member 50a, hot air flows capable of traveling sufficient distances throughout a wide region can be created. The hot air flows blown from the third outlet 18c near the bottom surface of the lower mount plate 40b are similar to the aforementioned hot air flows.
Further, the second air-direction changeable member 50b intercepts hot air proceeding toward the third corner F. The hot air impinged on the second air-direction changeable member 50b changes its flow direction at substantially a right angle and then is blown through the second outlet 18b toward the door 15. This can provide hot air flows with greater air velocities, which can reach the vicinity of the door 15, in compassion with the case where there is no air-direction changeable member. Further, the hot air flows toward the inlet 17 and thus circulates. Hot air flows caused by hot air blown from the fourth outlet 18d are similar to the aforementioned hot air flows. Consequently, it is possible to ensure sufficient hot air, thus uniformizing the temperature distribution at the intermediate portion between the upper and lower mount plates 40a and 40b within the heating room.
From above, when performing heating cooling with the heating cooker 1 configured as previously described, hot air is blown from the outlets 18a to 18d uniformly in the lateral-width direction of the heating room 12 and then is uniformly spread in the depth-wise direction, thereby providing a uniform temperature distribution within the heating room 12. This enables cooking without causing heating unevenness.
The temperature distribution at the region between the upper mount plate 40a and the top wall 33 of the heating room 12, namely the temperature distribution near the surface of the upper mount plate 40a, varies depending on the position of the first air-direction changeable member 50a. Therefore, there will be described the temperature distribution at the surface of the upper mount plate 40a when the position of the first air-direction changeable member 50a is changed, on the basis of Fig. 6 and Figs. 7(a) to 7(f). Fig. 6 is a view illustrating the outlets in detail, and Figs. 7(a) to 7(f) are views illustrating the temperature distribution near the surface of the upper mount plate for respective different positions of the first air-direction changeable member 50a, wherein there are shown the results of varying the position of the first air-direction changeable member 50a while the upper and lower mount plates are housed within the heating room and hot air is blown from all the outlets. The arrows shown in Fig. 6 indicate the direction of the rotation of the centrifugal fan 22.
Further, in Fig. 6, E3 indicates a position on the vertical straight line passing through the rotation shaft of the centrifugal fan 22, namely a position on the bisector which evenly divides the back wall 32 into two parts, and E6 indicates a position in the vicinity of the side wall 31 at the flow direction side. E5 indicates the intermediate position between E3 and F6, E1 indicates the intermediate position between the side wall 31 at the opposite side and E3, E2 indicates the intermediate position between E1 and F3, and E4 indicates the intermediate position between E3 and F5.
When the first air-direction changeable member 50a is positioned at E5 or E6, hot air can be easily flowed toward the flow direction side within the heating room 12 and the effect of blowing hot air by the effects of the first air-direction changeable member 50a is degraded, as shown in Figs. 7(e) and 7(f). This reduces the traveling distance of hot air flowing toward the door 15. Consequently, high-temperature portions will occur in the flow direction side near the back wall 32 within the heating room 12 while low-temperature portions will occur near the door 15 at the opposite side.
When the first air-direction changeable member 50a is positioned at E1, hot air can not easily proceed toward the flow direction side within the heating room 12 and also hot air is excessively concentrated at the end portion of the first outlet 18a in the opposite side and then blown therefrom, as shown in Fig. 7(a). This induces concentration of high-temperature portions at the opposite side within the heating room 12.
When the first air-direction changeable member 50a is positioned at E2, E3 or E4, it is possible to adequately achieve both the blowing of hot air toward the flow direction side within the heating room 12 and the effect of blowing hot air by the effects of the first air-direction changeable member 50a, as shown in Figs. 7(b), 7(c) and 7(d). Namely, it is possible to provide a preferable temperature distribution within the entire heating room 12. However, when the first air-direction changeable member 50a is positioned at E2 or E4, there are found some bias of hot air and some nonuniformity in the temperature distribution in the lateral-width-wise direction of the heating room 12, near the door 15 within the heating room 12, as shown in Figs. 7(b) and 7(d). This is because the positions of E2 and E4 are in the opposite side or the flow direction side beyond the position between the vertical straight line passing through the most flow direction side point on the outer circle defined by the centrifugal fan 22 and the vertical straight line passing through the most counter flow direction side point on the outer circle defined by the centrifugal fan 22. Namely, when the hot air from the centrifugal fan 22 changes its direction by the first air-direction changeable member 50a, the hot air flows are tend to be biased in the lateral-width direction of the heating room 12.
Therefore, it is preferable that the first air-direction changeable member 50a is positioned between the vertical straight line passing through the most flow direction side point on the outer circle defined by the centrifugal fan 22 and the vertical straight line passing through the most counter flow direction side point on the outer circle defined by the centrifugal fan 22, as the case of E3, namely within the region between the two straight vertical lines passing thorough the most flow direction side point and the most counter flow direction side point on the outer circle defined by the centrifugal fan 22, as shown in Fig. 6. In this case, it is possible to cause the temperature distribution within the heating room 12 to be more preferably uniformized.
Further, the aforementioned embodiment can provide the aforementioned effects without suffering from adverse influences of the height-to-width dimension ratio of the heating room 12. Here, as shown in Fig. 6, the height-wise length of the heating room 12 is designated as T, the lateral-width-wise length thereof is designated as W and the height-to-width dimension ratio thereof is designated as P = T/W.
Here, there will be described, using Figs. 8(a) to 8(f), the temperature distributions on the upper heating plate 40a for respective parameters, wherein the height-to-width ratio (P = T/W) of the heating room 12 is used as an independent parameter and the height-to-width ratio P is set to 1.0, 0.7 and 0.5. Figs. 8(a) to 8(f) are views illustrating the temperature distributions near the surface of the upper mount plate for different height-to-width ratios (P = T/W) of the heating room and illustrates the results of varying the value of the height-to-width ratio (P = T/W) of the heating room while the upper and lower mount plates are housed within the heating room and hot air is blown from all the blowing openings, by making comparison between a conventional heating cooker and the heating cooker according to the present embodiment. Further, in Figs. 8(a) to 8(f), the height-wise length T of the heating room 12 is maintained constant and the lateral-width-wise length W is varied, and therefore the lateral width increases with decreasing value of the height-to-width ratio (P = T/W) of the heating room 12.
On the upper mount plate 40a within the heating room 12 of a conventional heating cooker shown in Figs. 16 to 19, in the case where P is 0.7 or less, hot air blown from the first outlet 18a does not reach the side of the door 15, as shown in Figs. 8(a) to 8(c). Consequently, there prominently appears a temperature difference between the side of the door 15 and the side of the back wall 32 on the upper mount plate 40a.
On the other hand, on the upper mount plate 40a within the heating room 12 of the heating cooker according to the present embodiment, hot air blown from the first outlet 18a reaches the side of the door 15 for any value of the height-to-width ratio (P = T/W) of the heating room. Thus, there is a small temperature difference between the side of the door 15 and the side of the back wall 32 on the upper placing plate 40a. Therefore, the heating cooker according to the present embodiment can prominently offer the effect of alleviating heating unevenness along the direction toward the door 15 from the back wall 32 within the heating room 12. In particular, in the case where P is 0.7 or less, namely in the case of a heating cooker with a heating room 12 which is plan form in the lateral-width-wise direction, the heating cooker according to the present embodiment can offer more prominent effects.
Further, hot air blown from the third outlet 18c near the bottom surface of the lower mount plate 40b can provide a temperature distribution similar to the temperature distribution provided by the aforementioned hot air flows.
Next, another embodiment of the present invention will be described on the basis of the drawings. Fig. 9 is a front view illustrating a heating cooker according to another embodiment of the present invention. Fig. 10 is a side cross sectional view illustrating the heating cooker along with the directions of air flows (arrows). Fig. 11 is a view illustrating the directions of air flows within the heating cooker. Fig. 12 is a view illustrating the heating distribution near the surface of the upper mount plate. In the description of the structure of the heating cooker 2 according to another embodiment of the present invention, description of the same structures as those of the heating cooker 1 according to one embodiment of the present invention shown in Figs. 1 to 5 will be omitted, and only the structures different therefrom will be described hereinafter. Arrows shown in Fig. 9 indicate the direction of the rotation of the centrifugal fan 22.
The first outlet 18a and the third outlet 18c are formed from plural rows of holes which are evenly spaced apart from one another along the longer sides of the back wall 32 and have substantially a rectangular shape. The rectangular-shaped areas are referred to as blowoff regions and the areas including no hole formed therein at the flow direction side with respect to the blowoff regions are referred to as closed regions. Namely, the closed regions include the air-flow intercepting wall including no hole formed therein which is positioned in the flow direction side of the wall face of the heating room 12, while the blowoff regions include the outlets positioned in the opposite side from the flow direction side of the wall face of the heating room 12.
Here, "the flow direction side" means the side toward which the centrifugal fan 22 rotates or the downstream side of air flows caused by the centrifugal fan 22, and "the opposite side from the flow direction side" means the opposite side from the side toward which the centrifugal fan 22 rotates, or the upstream side of air flows caused by the centrifugal fan 22. In the present embodiment, at an upper portion of the heating room 12 such as a region above the upper mount plate 40a, the flow direction side corresponds to the right-half side of the heating room 12 when the heating room 12 is viewed from the front side and the opposite side corresponds to the left-half side thereof. At a lower portion of the heating room 12 such as a region below the lower mount plate 40b, the flow direction side corresponds to the left-half side of the heating room 12 when the heating room 12 is viewed from the front side and the opposite side corresponds to the right-half side thereof. At an intermediate portion of the heating room 12 such as the region between the upper mount plate 40a and the lower mount plate 40b, on the right of the centrifugal fan 22, the flow direction side corresponds to the lower-half side of the heating room 12 when the heating room 12 is viewed from the front side and the opposite side corresponds to the upper-half side thereof, while on the left of the centrifugal fan 22 the flow direction side corresponds to the upper-half side and the opposite side corresponds to the lower-half side.
The first outlet 18a is formed to have an opening area which gradually decreases toward the opposite side. Namely, near the end portion of the first outlet 18a in the opposite side from the flow direction side, the number of vertically-arranged punched holes decreases from three to two and one in the counter-flow direction direction, and therefore the opening area of the first outlet 18a gradually decreases toward the opposite side from the flow direction side. Near the end portion of the first outlet 18a in the opposite side from the flow direction side, the edge thereof defined by the arranged punched holes, at the opposite side from the flow direction side, is inclined along the direction of flow. There is formed a triangular closed region such as a right-triangular closed region above the hypotenuse connecting the uppermost punched hole and the lowermost punched hole at the end portion of the first outlet 18a in the opposite side from the flow direction side. There is formed no outlet in this triangular closed region.
With the conventional configuration, air is concentrated and compressed at the opposite side of the fan casing 21 by the spiral hot air flows and then the air is blown out from the end portion of the first outlet 18a in the opposite side. However, due to the existence of the triangular closed regions, hot air will not be blown from the portion which could blow air with a greatest velocity. Consequently, hot air will be blown from the first outlet 18a at substantially the same blowing velocity, at the end portion in the opposite side, the middle portion and the end portion in the flow direction side. This can equalize the traveling distances of hot air within the heating room 12 to send uniform hot air into the heating room 12, thereby alleviating the heating unevenness in the object to be heated S.
Further, as shown in Fig. 13, the end portion of the first outlet 18a in the flow direction side is positioned beyond the bisector which evenly divides the back wall 32 into the flow direction region and the opposite region, but within an area including a portion of the flow direction region. More specifically, the end portion of the first outlet 18a in the flow direction side is positioned in the flow direction side with respect to the bisector of the back wall 32, but not beyond the vertical straight line L passing through the most flow direction side point on the outer circle defined by the centrifugal fan 22. Consequently, as shown in Fig. 11, there will be no air blown into the heating room 12 from the flow direction side and thus hot air will not be concentrated at the flow direction side within the heating room 12 more than necessary, thereby preventing heat accumulation in the vicinity of the side wall 31 at the flow direction side.
The second outlet 18b and the fourth outlet 18d are formed from a plurality of holes placed on the right and left of the inlet 17 and are formed to have a circular shape with a small region.
The third outlet 18c is placed at the position which is rotationally displaced by 180 degrees from the first outlet 18a about the center shaft of the centrifugal fan 22, namely the center of the back wall 32. The third outlet 18c is formed to have a shape similar to that of the first outlet 18a. The end portion of the third outlet 18c in the opposite side is formed to have an opening area which gradually decreases toward the opposite side. Namely, near the end portion of the third outlet 18c in the opposite side from the flow direction side, the number of vertically-arranged punched holes decreases from three to two and one in the counter-flow direction direction, and therefore the opening area of the first outlet 18a gradually decreases toward the opposite side from the flow direction side. Near the end portion of the third outlet 18c in the opposite side from the flow direction side, the edge thereof defined by the arranged punched holes, at the opposite side from the flow direction side, is inclined along the direction of flow. There is formed a triangular closed region such as a right-triangular closed region below the hypotenuse connecting the uppermost punched hole and the lowermost punched hole at the end portion of the third outlet 18c in the opposite side from the flow direction side. There is formed no outlet in this triangular closed region. As shown in Fig. 13, the end portion of the third outlet 18c in the flow direction side is positioned in the flow direction side with respect to the bisector of the back wall 32, but not beyond the vertical straight line L passing through the most flow direction side point on the outer circle defined by the centrifugal fan 22.
With the aforementioned configuration, hot air blown by the centrifugal fan 22 flows into the heating room 12 as indicated by the solid-line arrows Ain Fig. 11. Even when the mount plate 40a and 40b is placed at the upper or lower stage; hot air passes over the surface and the bottom surface of the mount plate 40a and 40b. In Fig. 11, the solid-line arrows A indicate hot air flows within the heating room 12 and the broken-line arrows B indicate hot air flows within the air blower 20.
The triangular closed region formed in the opposite side from the flow direction side intercept hot air flows directed into the heating room 12 at the first corner D of the fan casing 21. This reduces the quantity of hot air blown into the heating room 12 at the portion. The hot air which has not been blown out therefrom will be blown out from the region of the first outlet 18a which extends from the middle portion thereof to the end portion in the flow direction side. Consequently, substantially the same quantity of hot air will be blown from the first outlet 18a, at the end portion in the opposite side, the middle portion and the end portion in the flow direction side.
With the conventional configuration, air is concentrated and compressed at the first corner D of the fan casing 21 by the spiral hot air flows and then the air is blown out from the end portion of the first outlet 18a in the opposite side. However, in the present embodiment, due to the triangular closed region, hot air will not be blown from the portion which could blow air with a greatest velocity. Namely, hot air will be blown from the more counter-flow direction first outlet 18a than the portion which could blow air with a greatest velocity. Consequently, hot air will be blown from the first outlet 18a at substantially the same blowing velocity, at the end portion in the opposite side, the middle portion and the end portion in the flow direction side. This can equalize the traveling distances of hot air within the heating room 12 to send uniform hot air into the heating room 12.
Consequently, as shown in Fig. 12, there will be no occurrence of unnatural high-temperature portions on the upper mount plate 40a as shown in Fig. 18 which is an example of the prior art. Namely, there will be no occurrence of unnatural high-temperature portions extending obliquely from the right-front side of the upper mount plate 40a.
Further, the end portion of the first outlet 18a in the flow direction side is positioned beyond the bisector which evenly divides the back wall 32 into the flow direction region and the opposite region, but within an area including a portion of the flow direction region. Namely, the end portion of the first outlet 18a in the flow direction side is spaced apart from the end portion of the back wall 32 in the flow direction side. In other wards, the closed region includes the air-flow intercepting wall including no hole formed therein which is positioned in the flow direction side in the back wall 32 of the heating room 12, while the blowoff region includes the outlets positioned in the opposite side from the flow direction side in the back wall 32 of the heating room 12. This can reduce the quantity of hot air flowing in the directions as shown in Fig. 19, namely the quantity of hot air proceeding toward the side wall 31 at the flow direction side within the heating room 12. Therefore, hot air will not be concentrated, and thus there will be no occurrence of excessively-heated portions as shown in Fig. 18. Namely, there will be no occurrence of excessively-heated portions in the right side of the upper mount plate 40a.
Further, since the hot air blown from the first outlet 18a is directed to the flow direction side by the spiral flows generated by the centrifugal fan 22, there will be no occurrence of insufficient heating in the right side portion of the upper mount plate 40a. Thus, as shown in Fig. 12, there will be a heating distribution in which high-temperature portions appear at the middle portion of the upper mount plate 40a and optimally-heated portions are entirely spread. Further, hot air blown from the third outlet 18c near the bottom surface side of the lower mount plate 40b causes a heating distribution similar to that caused by the aforementioned hot air flows.
Consequently, when heating cooking is performed with the heating cooker 2 configured as described above, hot air is evenly blown from the outlets 18a to 18d and there will be provided a uniform heating distribution as shown in Fig. 12. Further, as can be seen from Fig. 12, assuming that the objects to be heated S on the mount plates 40a and 40b are, for example, flat-shaped cake dough which are entirely spread over the mounting portions of the mount plates 40a and 40b, heating unevenness can be entirely alleviated, and high-temperature portions can be created uniformly in the lateral-width-wise direction at the middle portions of the mount plates 40a and 40b, which can alleviate the apparent unnaturalness of the baked color due to heating, thereby enabling proper heating cooking.
The heating distribution at the region between the upper mount plate 40a and the top wall 33 of the heating room 12, namely the heating distribution near the surface of the upper plate 40a, varies depending on the position of the end portion of the first outlet 18a in the flow direction side. Therefore, on the basis of Fig. 13 and Figs. 14(a) to 14(e), there will be described the heating distribution near the surface of the upper mount plate 40a when the position of the end portion of the first outlet 18a in the flow direction side is varied. Fig. 13 is a view illustrating the outlets in detail, and Figs. 14(a) to 14(e) are views illustrating the heating distributions at the surface of the object to be heated S placed on the surface of the upper mount plate, for respective different positions of the end portion of the first outlet 18a in the flow direction side, wherein there are shown the results of varying the position of the end portion of the first outlet 18a in the flow direction side while the upper and lower mount plates are housed within the heating room and hot air is blown from all the outlets. The arrows shown in Fig. 13 indicate the direction of the rotation of the centrifugal fan 22.
Further, E1 in Fig. 13 indicates a position on the vertical straight line passing through the rotation shaft of the centrifugal fan 22, namely a position on the bisector which evenly divides the back wall 32 into two parts, and E5 indicates a position in the vicinity of the side wall 31 at the flow direction side. E2, E3 and E4 indicate positions on respective lines which evenly divide the region between E1 and E5 into four parts.
When the end portion of the first outlet 18a in the flow direction side is positioned at E4 and E5, the quantity of hot air proceeding toward the side wall 31 in the flow direction side within the heating room 12 becomes large, thus resulting in occurrences of excessively-heated portions at the end portion of the upper mount plate 40a in the flow direction side, as shown in Fig. 14(d) and Fig. 14(e). Also, when the end portion of the first outlet 18a in the flow direction side is positioned at E1, the quantity of hot air proceeding toward the end portion of the upper mount plate 40a in the flow direction side becomes smaller, thus resulting in occurrences of insufficiently-heated portions at the right-front portion of the upper mount plate 40a as shown in Fig. 14(a), contrary to when the end portion of the first outlet 18a in the flow direction side is positioned at E4 and E5.
When the end portion of the first outlet 18a in the flow direction side is positioned at E2 and E3, there will be no occurrence of excessively-heated portions and insufficiently-heated portions, thus providing an entirely uniform heating distribution, as shown in Figs. 14(b) and 14(c). Here, when the end portion of the first outlet 18a in the flow direction side is positioned at E2, there is a smaller bias of high-temperature portions toward the right side of the upper mount plate 40a than when the end portion of the first blowing openings 18a in the flow direction side is positioned at E3. Consequently, the appearance of the object to be heated S such as the baked color will be more preferable when the end portion of the first outlet 18a in the flow direction side is positioned at E2.
From above, it is preferable that the end portion of the first outlet 18a in the flow direction side exist at the flow direction side with respect to the bisector of the back wall 32, but not beyond the vertical straight line L passing through the most flow direction side point on the outer circle defined by the centrifugal fan 22.
Near the end portion of the first outlet 18a in the opposite side from the flow direction side, the edge thereof defined by the arranged punched holes, at the opposite side from the flow direction side, is inclined along the direction of flow. There is formed a triangular closed region such as a right-triangular closed region above the hypotenuse connecting the uppermost punched hole and the lowermost punched hole at the end portion of the first outlet 18a in the opposite side from the flow direction side. By setting the inclination of the hypotenuse connecting the uppermost vertex and the lowermost vertex of this right triangle as follows, proper heating can be achieved within the heating room 12. Here, as shown in Fig. 13, the height-wise length of the heating room 12 is designated as T, the lateral-width-wise length thereof is designated as W and the height-to-width dimension ratio thereof is designated as P = T/W. Further, the height-wise length of the hypotenuse of the right triangle is designated as t, the lateral-width-wise length is designated as w, and thus the inclination of the hypotenuse is designated as p = t/w.
Here, there will be described, using Fig. 15, the heating distributions at the region between the upper mount plate 40a and the top wall 33 of the heating room 12, namely the heating distribution near the surface of the upper mount plate 40a, when the height-to-width ratio P is set to 1.0, 0.7 and 0.5 and the height-to-width ratio p of the hypotenuse is set to 1.0, 0.7 and 0.5 wherein the height-to-width ratio (P = T/W) of the heating room and the inclination (p = t/w) of the hypotenuse are used as independent parameters. Fig. 15 is a view illustrating the heating distributions at the surface of the object to be heated S placed on the upper mount plate when the height-to-width ratio (P = T/W) of the heating room and the inclination (p = t/w) of the shape of the end portion of the outlet in the opposite side are varied, wherein there are shown the result of varying the value of the height-to-width ratio (P = T/W) of the heating room and the inclination (p = t/w) of the shape of the end portion of the outlet in the opposite side while the upper and lower mount plates are housed within the heating room and hot air is blown from all the outlets.
In the case where P is 0.7 or less, high-temperature portions are not excessively accentuated at the left-front side of the upper mount plate 40a, thus resulting in a preferable heating distribution, in comparison with other cases. This is because there are smaller concentrations of hot air at the first corner D and the third corner F of the fan casing 21 than those at the second corner E and the fourth corner G.
When P is 0.7 or less, the height-wise dimension of the fan casing 21 is smaller than the lateral-width-wise dimension. Therefore, the quantity of hot air blown from the centrifugal fan 22 to the shorter height-wise edge of the fan casing 21 will be smaller than the quantity of air blown to the longer lateral-width-wise edge of the fan casing 21. Consequently, there will be smaller concentrations of hot air at the first corner D and the third corner F which exist in the opposite side of the longer lateral-width-wise edges than those at the second corner E and the fourth corner G which exist in the opposite side of the shorter height-wise edges. Thus, a smaller quantity of hot air will be blown from the opposite side of the outlet. Consequently, the hot air which has not been blown will flow toward the flow direction side and then is blown from the flow direction side of the outlets. This can provide a proper heating distribution in which high-temperature portions are not excessively biased toward the left-front side of the upper mount plate 40a.
Further, as can be seen from Fig. 15, in the case where P is equal to or greater than p, the right end portion of high-temperature portions is not excessively biased toward the back wall 32 on the upper mount plate 40a and is concentrated at the middle portion. This is because the triangular closed region existing at the end portion of the first outlet 18a in the opposite side reduces the quantity of blown hot air, out of the hot air which has been concentrated at the first corner D within the fan casing 21 by the spiral air flows from the centrifugal fan 22. Consequently, the hot air which has not been blown out therefrom will flow toward the flow direction side and is blown out from the flow direction side of the outlet. This eliminates the difference in the quantity of blown air between the opposite side and the flow direction side of the outlets, thus preventing excessive bias of high-temperature portions toward the back wall, in the flow direction side.
Hot air blown from the third outlet 18c near at the bottom surface side of the lower mount plate 40b causes a heating distribution similar to that caused by the aforementioned hot air flows.
While the examples of applications of the present invention have been described on the basis of the drawings, the present invention is not limited to the aforementioned embodiments and variations and modifications may be made thereto without departing from the scope of the present invention. For example, the present invention can be applied to various types of heating cooker equipped with an axial fan or a turbo fan, etc., as the air blower, instead of a centrifugal fan, to achieve similar effects to the aforementioned effects.
Also, there may be provided an air blower constituted by a fan casing, a heater and a centrifugal fan, within the heating room. In this case, the air blower is placed within the heating room, and therefore the wall faces of the fan casing constitute a portion of the wall faces of the heating room. Therefore, the outlets are formed in the wall faces of the heating room, namely in the wall faces of the fan casing.
Also, the outlets are not limited to be punched hole shapes. Also, instead of providing outlets in the back wall, it is possible to provide blowing openings in the side walls. In such a case, the positions of the outlets must be varied in accordance with the directions of blown air. Also, air-direction changeable members may be curved into a spherical shape.
Also, the position of the centrifugal fan is not limited to the center of the back wall. It is possible to guide hot wind from the centrifugal fan toward the blowing openings by using the flow path such as a pipe, a tube or the like.
The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the aforementioned embodiments. All modifications and variations which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

INDUSTRIAL APPLICABILITY

The present invention is applicable to various heating cookers having the oven cooking function, the electromagnetic-wave heating cooking function, the dielectric heating cooking function, the steam cooking function or at least two cooking functions selected from these cooking functions.

Claims

A heating cooker (1, 2) comprising:
an air blower (20) for blowing air in a predetermined flow direction; and

a heating room (12) having a wall face (32) for housing an object (S) to be heated, wherein

outlets (18a, 18b, 18c, 18d) for blowing air sent from said air blower (20) are formed in the wall face (32) of said heating room (12), and

air-flow intercepting walls for intercepting air flows are formed to be positioned in the said flow direction side with respect to said outlets (18a, 18b, 18c, 18d).
The heating cooker (1) according to claim 1, wherein said air-flow intercepting walls include air-direction changeable members (50a, 50b, 50c, 50d) for changing air flows which are blown from said outlets (18a, 18b, 18c, 18d), said air-direction changeable members (50a, 50b, 50c, 50d) being positioned at the end portions of said outlets (18a, 18b, 18c, 18d) in said flow direction side.
The heating cooker (1) according to claim 2, wherein said outlets (18a, 18b, 18c, 18d) are formed at the region lying from the end portion of the wall face of said heating room (12) at the opposite side from said flow direction side to the proximity of the middle portion of the wall face.
The heating cooker (1) according to claim 2, wherein said air blower (20) includes a centrifugal fan (22), said centrifugal fan (22) is placed to face the middle portion of the wall face of said heating room (12), and said air-direction changeable members (50a, 50b, 50c, 50d) are positioned within the region between two parallel lines (L) passing through the most flow direction side point and the most counter flow direction side point on the outer circle defined by said centrifugal fan (22).
The heating cooker (1) according to claim 4, wherein said outlets (18a, 18b, 18c, 18d) are formed at an upper portion, an intermediate portion and a lower portion of the wall face of said heating room (12), and said outlets (18b, 18d) formed at the intermediate portion of the wall face of said heating room (12) are placed at the both sides of said centrifugal fan (22).
The heating cooker (1) according to claim 2, wherein said air-direction changeable members (50a, 50b, 50c, 50d) are placed to extend from near the outer perimeter of the wall face (32) of said heating room (12) toward the center thereof in the proximity of the edge of the wall face of said heating room (12).
The heating cooker (1) according to claim 6, wherein said air-direction changeable members (50a, 50b, 50c, 50d) are placed to be inclined with respect to said flow direction.
The heating cooker (1) according to claim 7, wherein the end portions of said air-direction changeable members (50a, 50b, 50c, 50d) near the outer perimeter of the wall face (32) of said heating room (12) are positioned in said flow direction side, and the end portions of said air-direction changeable members (50a, 50b, 50c, 50d) near the center of the wall face (32) of said heating room (12) are positioned in the opposite side from said flow direction side.
The heating cooker (2) according to claim 1, wherein the wall face (32) of said heating room (12) includes closed regions having no outlets (18a, 18b, 18c, 18d) formed therein and blowoff regions having said outlets (18a, 18b, 18c, 18d) formed therein,
said closed regions include said air-flow intercepting walls positioned in said flow direction side of the wall face (32) of said heating room (12), and
said blowoff regions include said outlets (18a, 18c) positioned in the opposite side from said flow direction side of the wall face (32) of said heating room (12).
The heating cooker (2) according to claim 9, wherein said blowoff regions (18a, 18c) are biased toward the opposite side from said flow direction side of the wall face (32) of said heating room (12).
The heating cooker (2) according to claim 9, wherein the wall face (32) of said heating room (12) is constituted by a first region in said flow direction side and a second region in the opposite side from said flow direction side, and said blowoff regions (18a, 18c) include a part of said first region.
The heating cooker (2) according to claim 9, wherein plural mount plates (40a, 40b) for mounting the object (S) to be heated thereon are placed within said heating room (12) at upper and lower positions, and said blowoff regions (18a, 18c) are placed at a position above said mount plate (40a) placed at the uppermost stage and at a position below said mount plate (40b) placed at the lowermost stage.
The heating cooker (2) according to claim 9, wherein said blowoff regions (18a, 18c) are formed to have an opening area which gradually decreases toward the opposite side from said flow direction side.
The heating cooker (2) according to claim 9, wherein said heating room (12) has a rectangular wall face (32),
when the height of the wall face (32) of said heating room (12) is defined as T, the width thereof is defined as W and the height-to-width ratio thereof is defined as P = T/W, P is 0.7 or less, and
as to the straight line connecting the upper end and the lower end of the end portion of said blowoff regions (18a, 18c) at the opposite side from said flow direction side, when the height from the upper end to the lower end is defined as t, the width thereof in the width direction of the wall face (32) of said heating room (12) is defined as w and the inclination thereof is defined as p = t/w, P is p or more.
The heating cooker (1, 2) according to claim 1, wherein said heating room (12) has a rectangular wall face (32), and
said outlets (18a, 18c) are formed along the horizontal edges of the rectangular shape defining said wall face (32).
The heating cooker (1, 2) according to claim 15, wherein P is 0,7 or less, when the height of the wall face (32) of said heating room (12) is defined as T, the width thereof is defined as W and the height-to-width ratio thereof is defined as P = T/W.