CN105357790B - A kind of two-tube micro-wave oven for making radiator using spiral antenna with circular polarization - Google Patents

Abstract

The invention belongs to a double-tube microwave oven with a circularly polarized helical antenna as a radiator for food cooking. tube and its "L"-shaped energy-feeding waveguide composed of a vertical waveguide and a horizontal waveguide with a waveguide outlet, electrical boxes including power supplies, fans, and circuit boards, furnace doors, and circuit control buttons or knobs Circularly polarized helical antennas are installed at the waveguide exits of each energy-feeding waveguide, and the top of each antenna is placed on the bottom or top of the heating chamber. The bottom and top of the furnace are insulating dielectric plates . The invention has the characteristics of simple structure, light furnace body, high power density and high power in the furnace cavity, uniform heating of microwave radiation and heated objects, fast heating speed, long service life, and low production cost. It is especially suitable for microwave ovens. In fast food restaurants, restaurants, hotels and other places that require rapid heating.

Description

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

technical field

The invention belongs to a microwave oven for food cooking, in particular 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 with microwave radiation in the cavity and uniform heating of the object to be heated. 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 of 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, the diameter (minor diameter) φ3.0mm of helix, pitch t=5mm, the number of turns n=4, (helical antenna) bar body 7-1 height 15mm, diameter φ3.0mm; Power supply 9 present embodiment adopts switch power supply.

Claims (5)

1. a kind of two-tube micro-wave oven for making radiator using spiral antenna with circular polarization, including micro-wave oven casing, in housing Heating chamber and isolate with heating chamber set containing the electricity including microwave magnetron and its energy regenerative waveguide, power supply, fan, circuit board Device case, located at the positive fire door of housing, the panel with circuit control button or knob, it is characterised in that the microwave magnetron and Its energy regenerative waveguide is the identical microwave magnetron of symmetrically arranged upper and lower two nested structure and its energy regenerative waveguide, each Spiral antenna with circular polarization is further respectively had at the waveguide outlet of energy regenerative waveguide, and each energy regenerative waveguide is by vertical waveguide " L " shape energy regenerative waveguide combined with the horizontal rectangular waveguide with waveguide outlet, the bottom plate and top plate of the heating chamber It is insulation medium board；Bottom microwave magnetron is anchored on the top of lower vertical waveguide and top microwave magnetron is then tight The bottom of upper vertical waveguide is fixed in, it exports aerial head and is then respectively placed in the waveguide of corresponding position, bottom energy regenerative The waveguide outlet of waveguide is located at the top of its horizontal rectangular waveguide and the waveguide outlet of top energy regenerative waveguide is then located at it The bottom of horizontal rectangular waveguide, waveguide outlet center line are respectively positioned on the center line of microwave heating chamber, upper and lower circular polarisation spiral The top of antenna is then respectively placed on the outer surface of microwave heating chamber top top plate and lower raft and passes through helical antenna Body of rod perpendicular fastener on the inwall of the rectangular waveguide of corresponding waveguide outlet institute face, heating chamber bottom and top Insulation medium board and the metallic plate of four sides in heating chamber are sealedly and fixedly connected.

2. make the two-tube micro-wave oven of radiator using spiral antenna with circular polarization as described in claim 1, it is characterised in that the circle Polarization helical antenna is isodiametric cylindrical helical antenna, and meets this condition of D/ λ=0.25~0.46, to form axial direction Radiation mode, in formula：The wavelength that big footpath that D is cylindrical helical antenna, λ are operational microwave, and the helical antenna shank diameter , its height identical with the diameter of helical antenna wire body is then equal with the distance between the upper and lower inwall of horizontal rectangular waveguide.

3. make the two-tube micro-wave oven of radiator using spiral antenna with circular polarization as described in claim 1, it is characterised in that described to add The bottom plate and top plate of hot chamber are insulation medium board, and its material is glass plate, microcrystal glass plate or ceramic wafer.

4. make the two-tube micro-wave oven of radiator using spiral antenna with circular polarization as described in claim 1, it is characterised in that " L " The distance between vertical waveguide and the forward and backward inwall of horizontal rectangular waveguide are equal in shape energy regenerative waveguide, the vertical ripple Conduit includes activation fragment, middle part transition waceguide section and the rectangular waveguide section being connected with microwave magnetron, wherein：Activation fragment it is vertical, 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 The distance between the left and right inwall of activation fragment is identical, and narrow side is then identical with the distance between the left and right inwall of rectangular waveguide section, The ratio between the distance between the distance between left and right inwall of rectangular waveguide section and the left and right inwall of activation fragment are 1 ﹕ 2.0-3.0.

5. make the two-tube micro-wave oven of radiator using spiral antenna with circular polarization as described in claim 1, it is characterised in that the band The distance between upper and lower inwall of horizontal rectangular waveguide of waveguide outlet and the left and right inwall of rectangular waveguide section in vertical waveguide The distance between it is identical；And the waveguide outlet is rectangular opening or round mouth.