Convection oven

Abstract

To provide a convection oven which can effectively perform radiation heating and convection heating while considering characteristics of a heater.SOLUTION: A convection oven 1 of the invention includes: a heating chamber 120 in which an objected to be heated (a heated object) is heated; cooking tray receivers 130 provided on both side walls of the heating chamber 120; a blower 140 which is disposed at a blower chamber 121 formed through the top surface wall of the heating chamber 120; and a plurality of heating members 150 each including a heating element which generates heat by energization. The heating member 150 includes, as upper heaters 150A, a sheath heater 151A, 151B, which is formed by enclosing a nichrome wire with a metal pipe and mainly emits a far infrared ray, and a carbon heater 152A which is formed by enclosing a carbon filament with a glass pipe and mainly emits an intermediate infrared ray. The sheath heater 151A used as the upper heater is disposed so as to receive air supplied from an air outlet 122. The heating member 150 includes the sheath heater 151B as a lower heater 150B.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a convection oven, and more particularly to a technique for effectively performing heating and cooking in order to accommodate a variety of cooking modes. [Background technology]

[0002] A convection oven is provided with a tray on which an object to be heated, such as bread or pizza, is placed in a heating chamber, heaters that generate heat by resistance heating are disposed above and below the tray in the heating chamber, and the object to be heated on the tray is cooked by radiant heat from the heaters. Also, the air blown into the heating chamber from a blower is heated by the heat from the heater and convected, thereby achieving uniform heating by convection.

[0003] Conventional convection ovens often use sheathed heaters, whose surface becomes very hot. Sheathed heaters are formed by surrounding a nichrome wire, which generates heat when electricity is passed through it, with a metal pipe placed between them and an insulator. The metal pipe surrounding the nichrome wire has a high thermal conductivity, so it easily transfers heat to the airflow, and sheathed heaters are often used as heating elements for convection ovens.

[0004] By the way, a sheath heater is a heater that mainly radiates so-called far-infrared rays, which have a long wavelength among infrared rays. Although far-infrared rays can effectively heat the surface of an object compared to near-infrared rays and mid-infrared rays, which have a short wavelength, they cannot reach the inside of an object and have the property that they are difficult to heat the inside of an object. In addition, the heater itself has a weakness in that it does not start up well and the start-up speed is slow. Therefore, when using a sheath heater for oven cooking, it takes a long time to preheat. Furthermore, the response to the electric power is poor, so heating elements using sheath heaters generally have poor controllability.

[0005] Therefore, when using a convection oven that only uses a sheath heater to cook food that requires slow heating, such as whole roasted chicken, gratin, or baked goods, not only will it take a long time to preheat and cook the food, but the surface may burn and the inside may not be cooked.

[0006] In addition to the need for a convection oven to slowly heat food such as roasted chicken, gratin, or baked goods, it is also required to heat to a high temperature in a relatively short time, such as toasting bread or baking pizza. However, with a convection oven that uses only a sheath heater, it is difficult to heat food to a crisp in a short time.

[0007] In view of such circumstances, a technique has been proposed for constructing a convection oven using various types of heaters (Patent Document 1).

[0008] The convection oven described in Patent Document 1 is equipped with a first heater that emits far-infrared rays near the ceiling wall that divides the heating chamber, and a second heater that contributes to convection heating on the rear wall. The combination of the first heater that emits far-infrared rays and the second heater that contributes to convection heating provides effective heating.

[0009] However, even in a convection oven such as that disclosed in Patent Document 1, heating by radiation relies on the first heater that emits far-infrared rays, which have poor responsiveness, and it is difficult to perform cooking such as toasting bread to a crisp in a short period of time.

[0010] Furthermore, if a heater that radiates near-infrared or mid-infrared rays, which have a short rise time and easily penetrate into an object, is used as a heater for convection heating, the filament that generates heat when electricity is passed through it is surrounded by a glass tube such as quartz glass, so the surface temperature of the glass tube is low and the thermal conductivity of the glass tube is not high, so the heat generated by the filament cannot be effectively converted into convection heat. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Patent Publication No. 2022-088138 Summary of the Invention [Problem to be solved by the invention]

[0012] The present invention has been made in consideration of these problems, and has an object to provide a convection oven that can effectively perform radiant heating and convection heating while taking into account the characteristics of the heater. [Means for solving the problem]

[0013] The present invention provides the following solutions.

[0014] A convection oven according to a first feature comprises a heating chamber for heating an object to be heated, a cooking dish tray provided on both side walls of the heating chamber and for placing a cooking dish on which the object to be heated is placed, a blower disposed in a blower chamber formed through the top wall of the heating chamber and for supplying air toward the heating chamber from an air outlet provided in the top wall, and a plurality of heating elements having heating elements that generate heat when electricity is passed through them, the heating elements including a sheathed heater formed by surrounding a nichrome wire with a metal pipe and emitting mainly far-infrared rays, and a carbon heater formed by surrounding a carbon filament with a glass tube and emitting mainly mid-infrared rays, and the sheathed heater is disposed to receive air supplied from the air outlet.

[0015] According to the first aspect of the invention, not only a sheathed heater that emits far-infrared rays is used as a heating element, but also a carbon heater that emits mid-infrared rays that have a short warm-up time and easily penetrate into the interior of an object, so that heat can be applied thoroughly to the interior while shortening preheating and heating times. Also, the sheathed heater, which is surrounded by a metal pipe with high thermal conductivity, is arranged to receive air supplied from the air outlet, so that the heat emitted from the sheathed heater can be effectively transferred to the air flow, generating large convection heat and improving the heating performance as a convection oven.

[0016] The invention relating to the second feature is the invention relating to the first feature, wherein the air outlets are multiple openings densely arranged toward the center of the top wall, and the heating member includes an upper heater arranged above the cooking dish holder, and the upper heater comprises multiple sheath heaters and carbon heaters, and the carbon heaters are arranged closer to the end of the top wall than the sheath heaters.

[0017] According to the invention relating to the second feature, since the air outlets are multiple openings densely arranged on the center side of the top wall, an air flow can be generated in a substantially vertical downward direction toward the heating chamber, and the high-temperature air that tends to stagnate in the upper part of the heating chamber can be uniformly convected in the heating chamber. In addition, although the carbon heater is surrounded by a glass tube that is weak against impact, it is used as an upper heater arranged above the cooking dish holder, so that the risk of damage due to contact with an object or the like can be reduced. Moreover, since the carbon heater is arranged on the end side of the top wall relative to the sheathed heater, the risk of contact with an object or the like is lower. Furthermore, since multiple sheathed heaters are arranged to receive air supplied from the air outlets arranged on the center side of the top wall, and multiple carbon heaters are arranged on the end side of the sheathed heater, when heating by convection, the heat generated from the sheathed heater is mainly used. And, when heating by radiation, radiant heat can be emitted from the carbon heaters arranged on both ends of the top wall toward the entire cooking dish, and uniform radiation heating can be performed.

[0018] The third feature of the invention is the second feature of the invention, further comprising a sheathed heater disposed approximately directly below the air outlet.

[0019] According to the third feature of the invention, the sheathed heater is provided approximately directly below the air outlet, so that the heat generated by the sheathed heater can be directly transferred to the air blown approximately vertically downward from the air outlet, and a large amount of convection heat can be generated even with a small amount of electricity.

[0020] The invention of the fourth feature is an invention of any one of the first to third features, which includes a lower heater arranged below the cooking dish holder, and the lower heater includes a sheathed heater formed by surrounding a nichrome wire with a metal pipe and emitting mainly far infrared rays.

[0021] According to the fourth aspect of the invention, the lower heater is provided below the cooking dish tray, so that heat generated in the lower part of the heating chamber can be used to effectively apply heat. Also, the lower heater is a sheathed heater surrounded by a metal pipe, so that the heater can be prevented from being damaged by objects falling on it. Effect of the Invention

[0022] According to the present invention, it is possible to provide a convection oven that is capable of effectively performing radiant heating and convection heating while taking into consideration the characteristics of the heater. [Brief description of the drawings]

[0023] [Figure 1] Fig. 1 is a perspective view of a convection oven according to the present invention as seen from the front, with Fig. 1(a) showing a state as seen from diagonally below, and Fig. 1(b) showing a state as seen from diagonally above. [Diagram 2] Fig. 2 is a perspective view of the convection oven according to the present invention as seen from the front, with Fig. 2(a) showing a state as seen from diagonally above and Fig. 2(b) showing a state as seen from diagonally below. [Diagram 3] FIG. 3 is a cross-sectional view taken along line AA in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that this is merely an example, and the technical scope of the present invention is not limited to this example.

[0025] The overall configuration of a convection oven 1 according to this embodiment will be described with reference to FIGS. 1 to 3.

[0026] Fig. 1 is a perspective view of a convection oven according to the present invention as viewed from the front. Fig. 1(a) shows a state as viewed from diagonally below, and Fig. 1(b) shows a state as viewed from diagonally above. Fig. 2 is a perspective view of a convection oven according to the present invention as viewed from the front. Fig. 2(a) shows a state as viewed from diagonally above, and Fig. 2(b) shows a state as viewed from diagonally below. Fig. 3 is a cross-sectional view taken along line AA in Fig. 2(b).

[0027] As shown in Figures 1 and 2, the convection oven 1 of the present invention is composed of a convection oven body 110, a heating chamber 120, a cooking dish receiver 130, a blower 140, a heater 150, an operation unit 160, and a control unit (not shown).

[0028] Convection oven body 110 is formed in a substantially rectangular parallelepiped shape, and defines inside a heating chamber 120. A front opening through which objects to be heated can be put in and taken out is provided on the front surface of convection oven body 110, and the front opening is covered by a door body 111 which can be opened and closed.

[0029] The heating chamber 120 heats an object to be heated placed on a cooking tray (not shown) using a heater 150 and a blower 140, and has a substantially rectangular parallelepiped shape. The heating chamber 120 has a substantially rectangular top wall 121 that defines its upper end, and the top wall 121 is provided with an air outlet 122 for supplying airflow from the blower 140 (described later) into the heating chamber 120. The air outlet 122 is a plurality of openings provided concentrically so that the central side of the substantially rectangular top wall 121 is densely packed.

[0030] The cooking tray support 130 is for placing a cooking tray (not shown) on which an object to be heated is placed, and in this embodiment, is configured by steps formed in the front-rear direction at a predetermined height on the left and right walls. That is, the cooking tray (not shown) is attached to and detached from the heating chamber 120 by sliding it in the front-rear direction along the cooking tray support 130 while the door body 111 is open. In this embodiment, the cooking tray support 130 is provided at a plurality of heights, and the height at which the cooking tray is placed can be changed depending on the size of the object to be heated and the cooking mode set by the operation unit 160.

[0031] The blower 140 generates an airflow for convection heating of the object to be heated in the heating chamber 120, and is installed in a blower chamber 141 formed above the top wall 121 constituting the heating chamber 120, as shown in Fig. 3. The rotating shaft of the blower 140 extends in a substantially vertical direction, and an airflow is generated by driving the rotating shaft by a motor (not shown). The top wall 121 is provided with an air outlet 122, and the airflow generated by the blower 141 flows downward substantially vertically from the air outlet 122 toward the heating chamber 120.

[0032] The heating member 150 is a heating element for generating radiant heat and convection heat, and includes a heating element that generates heat when electricity is applied. The convection oven 1 in this embodiment includes multiple types of heating members 150, and includes an upper heater 150A in the upper portion of the heating chamber 120, i.e., above the cooking dish receiver 130, and a lower heater 150B in the lower portion of the heating chamber 120, i.e., below the cooking dish receiver 130, as the heating member 150.

[0033] As shown in FIG. 1(a) and FIG. 2(a), the upper heater 150A includes a sheathed heater 151A formed by surrounding a nichrome wire with a metal pipe and emitting mainly far infrared rays, and a carbon heater 152A formed by surrounding a carbon filament with a glass tube and emitting mainly mid-infrared rays. The sheathed heater 151A constituting the upper heater 150A is disposed along the width direction directly below the air outlet 122 so as to receive air supplied from the air outlet 122. In addition, no reflector or the like is provided around the sheathed heater 151A, so that the heater surface receives air and can directly transfer heat. The carbon heater 152A constituting the upper heater 150A is disposed along the width direction at a position farther from the air outlet 122 than the sheathed heater 151A. As shown in FIG. 3, in this embodiment, the upper heater 150A is composed of two sheathed heaters 151A and two carbon heaters 152A, and the two sheathed heaters 151A are disposed directly below the air outlet 122 and toward the center of the heating chamber 120 in the front-to-rear direction, while the two carbon heaters 152A are disposed closer to the end of the heating chamber 120 in the front-to-rear direction than the sheathed heaters 151A.

[0034] In general, sheathed heaters are formed by surrounding a nichrome wire, which is the heating element, with a metal pipe, and mainly emit far-infrared rays. Far-infrared rays have difficulty penetrating into objects, so they only heat the very surface (0.1 to 0.2 mm). The maximum temperature of the heater is 600 to 800°C, and the radiated heat density is about 5 W / cm2, so the energy density is low. In addition, it takes several minutes to start up, and the responsiveness to current is low. Due to these characteristics, sheathed heaters are suitable for heating the surface, but heat is difficult to transmit to the inside of the heated object, so they are not suitable for slowly heating large objects.

[0035] On the other hand, carbon heaters are formed by surrounding a carbon filament, which is the heating element, with an insulator such as an inert gas in a quartz glass tube, and mainly emit mid-infrared radiation. Mid-infrared radiation easily penetrates into the interior of an object, making it suitable for heating the interior of a lump of heated material, especially one that contains a lot of moisture. The maximum temperature of the heater is 900 to 1,100°C, and the radiated heat density is about 14 W / cm2, making it a high energy density. It has a short start-up time of just a few seconds, excellent response to current flow, and easy temperature control.

[0036] In this embodiment, a sheath heater 151A and a carbon heater 152A are used in combination as the upper heater 150A.

[0037] 1(b) and 2(b), the lower heater 150B includes a sheathed heater 151B that is formed by surrounding a nichrome wire with a metal pipe and mainly emits far infrared rays. As shown in FIG. 3, the sheathed heater 151B constituting the lower heater 150B is disposed in two pieces along the width direction near the bottom wall of the heating chamber 120.

[0038] Operation unit 160 is formed on the upper front surface of convection oven body 110, and is composed of knobs for operating and setting heating time and cooking mode.

[0039] The convection oven 1 configured in this way uses not only the sheathed heaters 151A and 152A that emit far-infrared rays as the heating members 150, but also the carbon heater 151B that emits mid-infrared rays that have a short rise time and easily penetrate into the interior of an object, so it is possible to thoroughly apply heat to the interior while shortening the preheating and heating times. In addition, the use of a sheathed heater and a carbon heater in combination allows infrared rays of a wide range of wavelengths to be emitted simultaneously, reproducing the infrared wavelengths of charcoal grilling, which is ideal for searing and other cooking, thereby improving the taste of the heated food.

[0040] In addition, since the sheathed heater 151A, which is formed by surrounding it with a metal pipe with a high thermal conductivity, is arranged to receive air supplied from the air outlet 122, the heat generated from the sheathed heater 151A can be effectively transferred to the air flow, generating a large amount of convection heat and improving the heating performance of the convection oven 1.

[0041] Since the air outlets 122 are multiple openings densely arranged on the center side of the top wall, an air flow can be generated in a substantially vertically downward direction toward the heating chamber 120, and the high-temperature air that tends to stagnate in the upper part of the heating chamber 120 can be circulated uniformly within the heating chamber 120. Although the carbon heater 152A is surrounded by a glass tube that is weak against impacts, it is used as the upper heater 150A disposed above the cooking dish receiver 130, and therefore the risk of damage due to contact with an object or the like can be reduced.

[0042] Moreover, since the carbon heater 152A is disposed closer to the end of the top wall than the sheathed heater 151A, there is less risk of contact with objects. Furthermore, since the multiple sheathed heaters 151A are disposed to receive air supplied from the air outlet 122 disposed on the center side of the top wall, and the multiple carbon heaters 152A are disposed closer to the end than the sheathed heater 151A, when heating by convection, the heat emitted from the sheathed heater 151A is mainly used. When heating by radiation, the carbon heaters 152A disposed on both ends of the top wall can emit radiant heat toward the entire cooking dish, allowing uniform radiation heating.

[0043] In addition, since the sheathed heater 151A is provided approximately directly below the air outlet 122, the heat generated by the sheathed heater 151A can be directly transferred to the air blown approximately vertically downward from the air outlet 122, and a large amount of convection heat can be generated even with a small amount of electricity.

[0044] Furthermore, since the lower heater 150B is provided below the cooking tray receiver 130, heat generated at the lower part of the heating chamber 120 can be used to effectively apply heat. Also, since the lower heater 150B is a sheathed heater 151B surrounded by a metal pipe, the heater is less likely to be damaged even if an object falls, and it can be used safely. In particular, by using the sheathed heater 151A provided as the upper heater 150A and the sheathed heater 151B provided as the lower heater 150B in combination, it becomes easier to control the multi-function oven during low-temperature cooking.

[0045] For example, when toasting bread using the convection oven 1 configured as above, although it is necessary to apply heat to the inside of the bread, the main heating required is to brown the surface. In this case, heating using the sheathed heaters 151A and 151B is suitable, but since the sheathed heaters 151A and 151B take time to heat up, cooking takes a long time if they are used alone. For this reason, a heating method is required that uses both the carbon heater 151B and the sheathed heaters 151A and 151B to complete heating in a short time and to brown the surface to a suitable degree.

[0046] In this embodiment, the carbon heater 152A is configured as the upper heater 150A and is arranged at the same height as the sheath heater 151A, but this is not limited to this and the heater may be arranged at another height as long as it can perform effective heating by radiation.

[0047] Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments. Furthermore, the effects described in the embodiments of the present invention are merely a list of the most preferable effects resulting from the present invention, and the effects of the present invention are not limited to those described in the embodiments of the present invention.

[0048] Furthermore, the above-described embodiment has been described in detail in order to clearly explain the present invention, and the present invention is not necessarily limited to having all of the configurations described. [Industrial Applicability]

[0049] INDUSTRIAL APPLICABILITY The convection oven of the present invention is useful as a cooking device for cooking food such as bread. [Explanation of symbols]

[0050] 1. Convection oven 110 Convection oven body 120 Heating chamber 130 Cooking dish holder 140 Blower 150 Heating member 150A Top Heater 151A Sheathed heater 151B Carbon heater 150B Lower Heater 151B Sheathed heater 160 Operation section

Claims

1. A heating chamber for heating an object to be heated; A cooking tray holder is provided on both side walls of the heating chamber and is used to place a cooking tray on which the object to be heated is placed; a blower that is disposed in a blower chamber formed through a top wall of the heating chamber and supplies air to the heating chamber through an air outlet provided in the top wall; A plurality of heating members each having a heating element that generates heat when energized; The heating member includes an upper heater disposed above the cooking dish support, the upper heater being a sheath heater formed by surrounding a nichrome wire with a metal pipe and emitting mainly far infrared rays, and a carbon heater formed by surrounding a carbon filament with a glass tube and emitting mainly mid-infrared rays, a sheathed heater used as the upper heater is disposed so as to receive air supplied from the air outlet; The heating member includes a lower heater disposed below the cooking dish tray, the lower heater being formed by surrounding a nichrome wire with a metal pipe and emitting mainly far infrared rays. Convection oven.

2. The sheath heater is provided substantially directly below the air outlet.

2. The convection oven of claim 1.

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