CN105357790A - Double-tube microwave oven adopting circularly polarized helical antennae as radiators - Google Patents

Abstract

The invention provides a double-tube microwave oven adopting circularly polarized helical antennae as radiators and belongs to food cooking. The double-tube microwave oven comprises a casing, a heating chamber formed in the casing, an electric appliance box isolated from the heating chamber, an oven door as well as a panel provided with a circuit control button or knob, wherein the electric appliance box comprises an upper assembly of a magnetron and an L-shaped energy-feed waveguide tube thereof, a lower assembly of a magnetron and an L-shaped energy-feed waveguide tube thereof, a power supply, a fan and a circuit board, and lower identical structures, the upper assembly of the magnetron and the L-shaped energy-feed waveguide tube thereof and the lower assembly of the magnetron and the L-shaped energy-feed waveguide tube thereof adopt identical structure, and each L-shaped energy-feed waveguide tube is formed by combining a vertical waveguide tube and a horizontal waveguide tube provided with a waveguide outlet; the circularly polarized helical antennae are arranged at the waveguide outlets of the energy-feed waveguide tubes respectively, top ends of the antennae are arranged on the outer surface of a bottom plate or a top plate of the heating chamber correspondingly, and both the bottom plate and the top plate of the oven chamber are insulating dielectric plates. The double-tube microwave oven adopting the circularly polarized helical antennae as the radiators has the characteristics of simple structure, light oven body weight, high power density inside the oven chamber, high power, uniform microwave radiation and heating of heated materials, high heating speed, long service life, low production cost and the like and is particularly applicable to places such as a fast food restaurant, a restaurant, a hotel and the like which requires fast heating.

Description

A Double Tube Microwave Oven Using Circularly Polarized Helical Antenna as Radiator

technical field

The invention belongs to microwave ovens for food cooking, in particular to a double-tube microwave oven using a circularly polarized helical antenna as a radiator to radiate high-speed rotating electromagnetic waves (the rotation rate is the same as the operating frequency of the microwave source) to make heating (resonance ) Microwave oven in which the microwave radiation in the cavity and the object to be heated are heated evenly. When the microwave operating frequency is 2450MHz, the microwave rotation rate is 2.45×10 ⁹ r/sec (that is, the ultra-high-speed rotation speed is 1470×10 ⁸ rpm ).

Background technique

It has been nearly 70 years since the microwave oven was invented. Traditional microwave ovens include a shell, a microwave heating (resonance) cavity inside the shell, and a microwave-containing magnetron (microwave generator) and its energy-feeding waveguide isolated from the microwave heating cavity. , switching power supply (or transformer), cooling fan, electrical box including the control circuit board, the furnace door and circuit control panel on the front of the shell; the feeding of the microwave power usually has the following methods, one. The turntable Type microwave oven: this type of microwave oven is to open a rectangular window from an appropriate position on a side wall (usually the right side) of the microwave oven cavity, and this window is connected with the energy-feeding waveguide of the magnetron (microwave source). linear polarization field, and directly radiate microwaves (power) with a fixed electric field direction into the furnace cavity. The heating uniformity of the object to be heated (placed) on it, the household microwave oven commonly used by people many years ago is this type of turntable microwave oven. Although this type of microwave oven solves the heating (heating) uniformity problem to a certain extent, but Due to the complex structure, the weight of the furnace, and the periodic changes in the heating temperature of the object to be heated, the overall (especially the solid object) is still not evenly heated; second. Flat-plate microwave oven: This type of microwave oven feed waveguide is located at the bottom or bottom of the furnace cavity and the top, open a window directly on the top of the wide side of the waveguide, and install an insulating medium shaft in the center of the feed hole (square hole), and place an asymmetrical metal blade on the top of the shaft, and place it at the bottom of the shaft (outside the waveguide) ) to install a slow rotating motor, which drives the top blades to rotate through the rotating shaft, forming a so-called "mode stirrer". The object is evenly heated, but the power density in the furnace cavity and the uniform heating of the heated object are still difficult to effectively improve; the patent document with the announcement number CN204574146U and the invention name "Microwave Oven" belongs to this type of flat-panel microwave oven. The microwave oven is equipped with a waveguide and the first and second microwave stirring devices with drive motors respectively located on the bottom and top of the oven cavity (accommodating cavity) in order to make the microwave distribution in the oven cavity more uniform; in addition, Another flat-panel microwave oven is based on the above-mentioned structure, and the rotating shaft in the mode stirrer is replaced by a metal shaft, which forms an active antenna together with the metal blades, and the microwave power is directly radiated from the antenna blades into the oven cavity. In addition, a few years ago, Japan's Matsushita Corporation once launched a commercial dual-source microwave oven on the market, but its energy feeding device uses an active antenna, which rotates at a slow speed with a motor, and the two antennas are placed in the oven cavity respectively. The bottom and top of the microwave oven rotate in opposite directions relative to each other, and radiate microwave power to the food placed between the two antennas to achieve the purpose of rapid and uniform heating; It is complicated, the production cost is high, and there are still the problems of microwave distribution in the furnace cavity and poor heating of the object to be heated. The publication number is CN204648356U, and the patent document titled "Microwave Oven" is aimed at the disadvantages of the above-mentioned patented technology, such as complex structure, on the basis of improving a design of a microwave oven. The microwave oven is arranged on the outside of the box. Multiple magnetrons are arranged on the same waveguide, and the stirring motor is also arranged on the waveguide, and its main shaft is placed inside the waveguide, and the main shaft is connected with stirring blades. The microwave oven uses multiple magnetrons to share one waveguide tube and a stirring motor to reduce the production cost and overcome the high production cost defect of the previous patented technology. The microwave of each branch enters the through hole from the same microwave outlet, but there are disadvantages of microwave interference and affecting its power output;

Thereby, above-mentioned conventional microwave ovens all exist need to adopt electric motor and be provided with blade stirrer or (loading) turntable this kind of more complicated rotating system, and because what adopted is the motor transmission system of slow-speed rotating electric motor or belt deceleration mechanism, the stirring blade The rotation speed is limited or the microwaves of each branch enter the through hole from the same microwave outlet. The microwaves interfere with each other and affect their power output, and the microwave power density is low, and the heated object is still heated unevenly.

Contents of the invention

The purpose of the present invention is to aim at the defect that background technology exists, research and design a kind of double tube microwave oven that adopts circularly polarized helical antenna as radiator, to reach the structure of simplified microwave oven, furnace body weight is light, effectively improve heating chamber (oven chamber) The power density, microwave radiation and the heated object are heated evenly, the heating speed is fast, the service life is extended, and the production cost is reduced.

The solution of the microwave oven of the present invention is to adopt two sets of microwave energy feeding systems, and each set of systems uses a circularly polarized helical antenna as a microwave radiator, which is arranged at the waveguide outlet and placed on the outer bottom and top of the oven cavity respectively. And respectively cooperate with the magnetron and the "L" shaped waveguide composed of the vertical waveguide and the horizontal waveguide with the waveguide outlet, through the circularly polarized helical antenna arranged at the two waveguide outlets in the axial radiation mode from the bottom and the The top directly radiates high-speed rotating microwaves (electromagnetic waves) into the furnace cavity; that is, the present invention adopts two symmetrically arranged energy feeding systems with the same structure, one set is located at the outer bottom of the furnace cavity, and the other is located outside the furnace cavity. On the top, two sets of energy feeding systems directly radiate high-speed rotating microwaves into the furnace cavity in an axial radiation mode from bottom to top and top to bottom respectively, so as to achieve the purpose of the invention. Thereby the present invention adopts circularly polarized helical antenna to make the double-tube microwave oven of radiator and comprises microwave oven shell, is located at the heating cavity in the shell and is isolated from heating cavity and contains microwave magnetron and its energy-feeding waveguide, power supply, fan , the electrical box including the circuit board, the furnace door on the front of the shell, and the panel with circuit control buttons or knobs. The key is that the microwave magnetron and its energy-feeding waveguide are symmetrically arranged upper and lower two A microwave magnetron and its feeding waveguide with the same structure are provided, and circularly polarized helical antennas are respectively arranged at the waveguide exits of each feeding waveguide, and each feeding waveguide is composed of a vertical waveguide and a band The "L" shaped energy-feeding waveguide is composed of horizontal rectangular waveguides at the waveguide exit. The bottom plate and the top plate of the furnace cavity are both insulating dielectric plates; The upper microwave magnetron is fastened to the lower part of the upper vertical waveguide, and its output antenna heads are respectively placed in the corresponding waveguides, and the waveguide exit of the lower energy-feeding waveguide is set on the top of its horizontal rectangular waveguide. The waveguide exit of the upper feeding waveguide is set at the bottom of its horizontal rectangular waveguide, the centerline of the waveguide exit is located on the centerline of the microwave heating cavity, and the tops of the circularly polarized helical antennas are respectively placed in the corresponding microwave heating cavity The outer surface of the bottom or top plate and the rod body of the helical antenna are vertically fastened to the inner wall of the rectangular waveguide facing the corresponding waveguide outlet. Metal (wall) plates are sealed and fixedly connected.

The circularly polarized helical antenna is a cylindrical helical antenna of equal diameter, and satisfies the condition of D/λ=0.25～0.46 to form an axial radiation pattern, where D is the major diameter of the cylindrical helical antenna, λ For the wavelength of the working microwave, the diameter of the rod body at the lower end of the helical antenna is the same as that of the helical antenna wire body, and its height is equal to the distance (height) between the upper and lower inner walls of the horizontal rectangular waveguide. The bottom plate and the top plate of the furnace cavity are insulating dielectric plates made of glass plate, glass-ceramic plate or ceramic plate. The distance (i.e. depth) between the vertical waveguide and the front and rear inner walls of the horizontal rectangular waveguide in the "L" shaped energy feeding waveguide is equal, and the vertical waveguide includes (microwave) connected to the microwave magnetron. The excitation section, the middle transitional waveguide section and the rectangular waveguide section, wherein: the longitudinal and cross-sections of the (microwave) excitation section are rectangular, while the longitudinal section of the middle transitional waveguide section is a right-angled trapezoid, the cross-section is a rectangle, and the broadside of the right-angled trapezoid The distance between the left and right inner walls of the excitation section is the same, while the narrow side is the same as the distance between the left and right inner walls of the rectangular waveguide section. The distance between the left and right inner walls of the rectangular waveguide section is the same as the distance between the left and right inner walls of the excitation section. The ratio of the distance between them is 1:2.0-3.0. The distance (height) between the upper and lower inner walls of the horizontal rectangular waveguide with the waveguide outlet is the same as the distance between the left and right inner walls of the rectangular waveguide section in the vertical waveguide; and the waveguide outlet is a rectangular mouth, a square mouth or round mouth.

Because the present invention adopts two sets of microwave energy feeding systems, each set of systems uses a circularly polarized helical antenna as a microwave radiator, which is arranged at the waveguide outlet and placed on the outer bottom and top of the furnace cavity respectively, and is connected with the magnetic The control tube and the "L"-shaped waveguide composed of a vertical waveguide and a horizontal waveguide with a waveguide exit cooperate, and the circularly polarized helical antennas arranged at the exits of the two waveguides are respectively directed from the bottom and top to the furnace chamber in the axial radiation mode. Directly radiate circularly polarized waves rotating at high speed, and the rotation rate is the operating frequency of the microwave source, that is, when the frequency f=2450MHz, the microwave rotation rate is 2.45×10 ⁹ r/sec, which is equivalent to 1470×10 ⁸ The ultra-high-speed rotating wave of rpm; because the power is doubled, the power density in the furnace cavity, the microwave radiation and the heated object are heated evenly, and the heating speed is fast; in addition, the present invention saves the slow rotating motor and Loading turntable or stirring blade, or active antenna and other power and rotating parts, therefore, the present invention has the advantages of simple structure of microwave oven, light weight of furnace body, high power density and high power in the furnace cavity, microwave radiation and heated objects Uniformity, fast heating speed, long service life, and low production cost are especially suitable for fast food restaurants, restaurants, hotels and other places that require rapid heating.

Description of drawings

Fig. 1 adopts circularly polarized helical antenna as the structural representation (sectional view) of radiator microwave oven for the present invention;

In the figure: 1. Housing, 2. Furnace door, 3. Heating chamber, 3-1. Bottom plate of heating chamber, 3-2. Top plate of heating chamber, 4. Electrical box, 5. Magnetron, 6. "L" Shaped waveguide, 6-1. (Microwave) excitation section, 6-2. Transition waveguide section, 6-3. (Vertical waveguide) lower rectangular waveguide section, 6-4. Horizontal rectangular waveguide, 6-5. Waveguide Exit, 7. circularly polarized helical antenna, 7-1. (helical antenna) rod body, 8. circuit board, 9. power supply, 10. fan, 11. panel, 11-1. circuit control knob (or button).

detailed description

In this embodiment, a household microwave oven with a rated input power of 1200W (output power of 750W) and a microwave operating frequency of 2450MHz is taken as an example: Shell 1. Dimensions (height×width×depth) 480×510×460mm, heating chamber 3. Dimensions (height×width×depth) Width × depth) 300 × 400 × 400mm (48L), heating chamber bottom plate 3-1, top plate 3-2. Tube 5. Model 2M219, operating frequency F=2450MHz, the total height of the vertical waveguides in each "L" shaped waveguide 6 is 185mm, wherein: (microwave) excitation section 6-1 is the longitudinal height of the inner cavity 70mm, the transverse width 40mm, 80mm deep rectangular waveguide, the upper bottom surface of the transitional waveguide section 6-2 is the same as the cross section of the (microwave) excitation section 6-1, and the lower bottom surface is the same as the transverse section of the (vertical waveguide) lower rectangular waveguide section 6-3. Transitional waveguide section with the same cross-section and a height of 65mm, a rectangular waveguide section with a cross-section (width×depth) of 15×81mm and a cavity height of 52mm in the lower rectangular waveguide section 6-3, and a horizontal rectangular waveguide section (with waveguide outlet) 6- 4 is a rectangular waveguide of (height×width×depth) 15×282×81mm, and the waveguide outlet 6-5 adopts a square opening of 80×80mm in this embodiment; ) D=φ50mm, diameter (minor diameter) φ3.0mm of helix, pitch t=5mm, number of turns n=4, (helical antenna) bar body 7-1 high 15mm, diameter φ3.0mm; Power source 10 present embodiment adopts switch power supply.

Claims (5)

1. the two-tube microwave oven adopting spiral antenna with circular polarization to make radiator, comprise micro-wave oven casing, be located at heating chamber in housing and with heating chamber isolate arrange containing microwave magnetron and energy regenerative waveguide thereof, power supply, fan, circuit board is at interior electric appliance box, be located at the fire door in housing front, with the panel of control circui button or knob, it is characterized in that described microwave magnetron and energy regenerative waveguide thereof be symmetrically arranged on, the lower identical microwave magnetron of two nested structures and energy regenerative waveguide thereof, also spiral antenna with circular polarization is respectively equipped with at the waveguide outlet place of each energy regenerative waveguide, and " L " shape energy regenerative waveguide of each energy regenerative waveguide all for being combined with the horizontal rectangular waveguide of band waveguide outlet by vertical waveguide, base plate and the top board of described furnace chamber are insulation medium board, bottom microwave magnetron is anchored on the top of lower vertical waveguide, top microwave magnetron is then anchored on the bottom of upper vertical waveguide, it exports aerial head and is then placed in respectively in the waveguide of corresponding position, the waveguide outlet of bottom energy regenerative waveguide is located at the top of its horizontal rectangular waveguide, the waveguide outlet of top energy regenerative waveguide is then located at the bottom of its horizontal rectangular waveguide, waveguide outlet center line is all positioned on the center line of microwave heating chamber, the top of each spiral antenna with circular polarization to be then placed in respectively on the base plate of corresponding microwave heating chamber or the outer surface of top board and by the body of rod perpendicular fastener of helical antenna in corresponding waveguide export just right rectangular waveguide inwall on, be sealedly and fixedly connected with the metallic plate of four sides in the insulation medium board at top and heating chamber bottom furnace chamber.

2. the two-tube microwave oven adopting spiral antenna with circular polarization to make radiator, it is characterized in that described spiral antenna with circular polarization is isodiametric cylindrical helical antenna, and meet this condition of D/ λ=0.25 ~ 0.46, to form axial radiation pattern, in formula: D is the large footpath of cylindrical helical antenna, λ is the wavelength of operational microwave, the body of rod diameter being located at this helical antenna lower end is identical with the diameter of helical antenna line body, it is highly then equal with the distance between the upper and lower inwall of horizontal rectangular waveguide.

3. adopt spiral antenna with circular polarization to make a two-tube microwave oven for radiator, it is characterized in that the base plate of described furnace chamber and top board are insulation medium board, its material is glass plate, microcrystal glass plate or ceramic wafer.

4. the two-tube microwave oven adopting spiral antenna with circular polarization to make radiator, to it is characterized in that in described " L " shape energy regenerative waveguide before vertical waveguide and horizontal rectangular waveguide, distance between rear inwall is all equal, described vertical waveguide comprises the activation fragment be connected with microwave magnetron, middle part transition waceguide section and rectangular waveguide section, wherein: indulging of activation fragment, cross section is rectangle, and the longitudinal section of middle part transition waceguide section is right-angled trapezium, cross section is rectangle, the broadside of right-angled trapezium and an activation fragment left side, distance between right inside wall is identical, narrow limit then with rectangular waveguide Duan Zuo, distance between right inside wall is identical, rectangular waveguide Duan Zuo, distance between right inside wall and an activation fragment left side, ratio of distances constant between right inside wall is 1 ﹕ 2.0-3.0.

5. adopt spiral antenna with circular polarization to make a two-tube microwave oven for radiator, the distance between the upper and lower inwall of horizontal rectangular waveguide that it is characterized in that described band waveguide outlet is identical with the distance in vertical waveguide between the left and right inwall of rectangular waveguide section; And described waveguide outlet be rectangular opening, square opening or round mouth.