JP2010140657A - Induction heating cooking appliance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an induction heating cooking appliance capable of restraining common-mode noise generated at an inverter circuit from sneaking into an AC power source side, without complexifying a structure. <P>SOLUTION: A terminal of a grounding capacitor (a grounding part of a circuit board 46) constituting a noise filter unit 7b and a body case 2 are electrically connected through a board-case connecting part 68 at a position where the circuit board 46 and the body case 2 are opposed to each other. Further, the body case 2 and a grounding wire 67c (the earth) of a power source cord 67 are electrically connected at a case-power source connecting part 69 fitted at a position different from the board-case connecting part 68. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an induction heating cooker including an inverter circuit that receives power from an AC power supply and supplies a high-frequency current to a heating coil, and a noise filter circuit interposed between the AC power supply and the inverter circuit.

An inverter circuit that supplies a high-frequency current to a heating coil for induction-heating the cooking vessel has a high frequency and a high voltage, and therefore needs to be insulated from a casing made of metal. For this reason, the electric circuit unit including the inverter circuit is accommodated in a case made of an insulating material. In addition, a noise filter circuit is interposed between the AC power supply and the inverter circuit in order to prevent high-frequency noise (common mode noise) generated by the inverter circuit from entering the AC power supply side (for example, Patent Documents). 1-3).
Japanese Patent No. 3469056 Japanese Patent No. 2997633 JP 2006-086095 A

  In the noise filter circuit having the above-described conventional configuration, the earth terminal of the earth capacitor for short-circuiting the common mode noise and returning it to the inverter circuit side is, for example, drawn out of the case using a lead wire, Electrically connected. For this reason, a long lead wire is used. Such a long lead wire becomes an inductance with respect to a high frequency noise component of, for example, several MHz to several tens of MHz generated in the inverter circuit, and high frequency resistance is increased due to a skin effect.

  For this reason, the impedance between the earth terminal of the earth capacitor and the housing is increased, and common mode noise is less likely to be short-circuited by the earth capacitor. As a result, when the common mode noise circulates to the AC power supply side, a failure due to noise occurs in other devices connected to the AC power supply. In order to prevent this noise disturbance, it is also conceivable that a noise prevention coil or the like is interposed in the power cord connected to the lead wire or the AC power source. However, in this case, since the number of parts increases, the configuration becomes complicated and the cost increases.

  This invention is made | formed in view of the said situation, The objective provides the induction heating cooking appliance which can suppress that the common mode noise which arises in an inverter circuit wraps around to an alternating current power supply side, without complicating a structure. There is.

  In order to achieve the above-described object, an induction heating cooker according to the present invention includes a top plate on which a cooking container is placed, a heating coil that is disposed below the top plate and that induction-heats the cooking container, and an alternating current. An inverter circuit that receives a supply of power from a power source and supplies a high-frequency current to the heating coil, and an earth capacitor that is interposed between the AC power source and the inverter circuit, and has a common mode coil and one terminal connected to a ground potential A noise filter circuit comprising: a printed circuit board on which the inverter circuit and the noise filter circuit are mounted; a substrate case made of an insulating material in which the printed wiring board is accommodated; and the heating coil and the substrate case A housing made of a metallic material, and the printed wiring board is attached to the housing via the substrate case. The housing is grounded via a ground wire, and one terminal of the earth capacitor and the housing are electrically connected at a position where the printed wiring board and the housing face each other, The housing and the ground wire are electrically connected at a position different from a position where the printed wiring board and the housing face each other.

  According to the present invention, the terminal on the ground potential side of the earth capacitor constituting the noise filter circuit and the housing made of the metal material are electrically connected to the printed wiring board on which the noise filter circuit is mounted and the housing. Connected to. For this reason, the terminal on the ground potential side of the earth capacitor can be connected to the housing at a short distance, and the impedance between them can be reduced. Therefore, the noise suppression effect by the noise filter circuit can be enhanced without complicating the configuration, and the common mode noise generated in the inverter circuit can be suppressed from flowing to the AC power supply side.

(First embodiment)
Hereinafter, a first embodiment in which the present invention is applied to a stationary induction heating cooker (IH cooking heater) will be described with reference to FIGS.
FIG. 1 is an exploded perspective view of an induction heating cooker. As shown in FIG. 1, a main body 1 of an induction heating cooker is mounted on a main body case 2 (corresponding to a casing) made of a rectangular box-shaped metal material whose upper surface is open, and an upper surface of the main body case 2. And a top plate assembly 3. The top plate assembly 3 includes a top plate 4 made of glass, for example, and a top plate frame 5 made of metal, for example, aluminum, that supports the top plate 4. A cooking container W (see FIG. 3) is placed on the top surface of the top plate 4.

  A fan device 6 and an electric circuit unit 7 (see FIG. 2), which will be described later, are arranged on one side in the main body case 2 as viewed from the front, and a roaster unit 8 is arranged on the left side which is the other side. It is installed. In the main body case 2, a partition plate 10 extending in the front-rear direction is provided between the right fan device 6 and the electric circuit unit 7 and the left roaster unit 8. The inside of the main body case 2 is divided into left and right by the partition plate 10.

  The roaster unit 8 is provided with a roaster heater (not shown) disposed in a roaster casing 11 whose front surface is open, and a drawer unit 14 having a door 13 is detachably provided. A tray and a grill (both not shown) are attached to 14. A roaster exhaust port 15 is provided upward at the rear of the roaster casing 11. A roaster exhaust port 5a (indicated by a dotted line in FIG. 1) communicating with the roaster exhaust port 15 is provided at the rear of the top plate frame 5, and the air in the roaster casing 11 is supplied to the roaster exhaust port. It is discharged through the portion 15 and the roaster exhaust port 5a. A main body exhaust port 5b (shown by a dotted line in FIG. 1) is formed at the rear of the top plate frame 5 so as to be positioned on the left side of the roaster exhaust port 5a. The roaster exhaust port 5a and the main body exhaust port 5b are covered with an exhaust port cover 9 having a large number of ventilation holes.

  A partition 16 is disposed in the upper part of the main body case 2 so as to be positioned below the top plate 4. The partition 16 is arranged in a state straddling the right fan device 6 and the electric circuit unit 7 and the left roaster unit 8. The partition 16 is made of a non-magnetic conductive material, for example, aluminum, and forms a shallow rectangular container having a side wall 16a that rises on the outer periphery in a frame shape. The upper end of the side wall 16a Are in close contact with the lower surface of the top plate 4 through packing 17 (see FIG. 2) provided over the entire circumference. Here, the partition 16 is provided so as to partition the space below the top plate 4 into an upper space 18 and a lower space 19 (see FIG. 2). The upper space 18 formed between the top plate 4 and the partition 16 is a space in which the space between the top plate 4 and the partition 16 is sealed via the packing 17.

  In the upper space 18 in the partition 16, a plurality, in this case, two heating coils 21 and 22 for induction heating are arranged. These heating coils 21 and 22 are for induction heating the cooking vessel W placed on the top plate 4. The heating coils 21 and 22 are supported by the coil base 23 and are urged toward the upper top plate 4 by a spring 24 (see FIG. 2). A gap is formed so that the wind passes between the inner surface and the inner surface. A temperature sensor 25 (see FIG. 2) is provided at the center of the coil base 23 of each of the heating coils 21 and 22. The temperature sensor 25 is for detecting the temperature of the cooking container W placed on the top plate 4.

  Two communicating portions 26 each having an opening are formed in the right front portion of the partition 16 so as to be positioned in front of the right coil 22. In addition, an exhaust port 27 including an opening is formed in the left rear portion of the partition 16 so as to be positioned behind the left heating coil 21, and the right heating coil is formed in the rear of the left and right central portions of the partition 16. An exhaust port 28 is formed on the left rear side of 22.

  A terminal block opening 29 is formed at the center of the partition 16 so as to be positioned between the left and right heating coils 21 and 22. A part of the relay terminal block 30 is inserted into the terminal block opening 29, and the terminal block opening 29 is closed by the relay terminal block 30. The relay terminal block 30 is at the upper end portion of the partition plate 10 and is fixed to the center portion in the front-rear direction. The relay terminal block 30 is for electrically connecting the electric circuit unit 7 and the heating coils 21 and 22.

On the upper surface, which is inside the partition 16, is positioned between the two heating coils 21, 22 adjacent to the left and right, and between the front communication portion 26 and the rear exhaust ports 27, 28, The 1st partition part 36 extended in the left-right direction is provided, and the 2nd partition part 37 which partitions off between the right-and-left adjacent exhaust ports 27 and 28 is provided in the rear part side of this 1st partition part 36. . The upper surface of the partition 16 is between the outer periphery of the coil base 23 of the left heating coil 21 and the left side wall 16a, and between the outer periphery of the coil base 23 of the right heating coil 22 and the right side wall 16a. The third partitioning portions 38 for connecting the two are provided.
An operation panel unit 42 including an operation unit 40 including a switch and a display unit 41 is provided in front of the partition 16. The operation panel unit 42 is covered with a cover portion 42 a provided at the front portion of the top plate frame 5.

  Next, the configuration of the electric circuit unit 7 and the fan device 6 will be described with reference to FIG. FIG. 2 is a longitudinal side view taken along line XX in FIG. The electric circuit unit 7 and the fan device 6 are provided in a substrate case 45 made of an insulating material. The substrate case 45 is disposed on the right side of the partition plate 10 in the lower space 19 of the main body case 2. A circuit board 46 made of a single printed wiring board is accommodated at the bottom of the board case 45. Thereby, the circuit board 46 is fixed to the bottom of the main body case 2 via the board case 45. Further, the circuit board 46 is disposed so as to be parallel to the bottom surface of the main body case 2.

  The electric circuit unit 7 is configured by mounting electric components 66 described later on the circuit board 46. The electric circuit unit 7 includes an inverter circuit 88 that supplies a high-frequency current to the heating coils 21 and 22, a control circuit 97 that controls the inverter circuit 88 and the like, and a noise filter circuit 80 (see FIG. 4). Electric power is supplied to such an electric circuit unit 7 through a power cord 67.

  In the present embodiment, the control unit 7a is configured by the inverter circuit 88 and the control circuit 97 and the portion of the circuit board 46 on which these are mounted. In addition, the noise filter unit 7b is configured by the noise filter circuit 80 and a portion of the circuit board 46 on which these are mounted.

  A first intake duct 47 is provided on the rear side of the substrate case 45 in the main body case 2. The upper portion of the first intake duct 47 is an intake port 48, and the intake port 48 is a first intake port 49 (shown by a dotted line in FIG. 1) provided on the right side of the rear portion of the top plate frame 5. ). The first intake port 49 also corresponds to the main body intake port. The first intake port 49 is covered with an intake port cover 49a having a large number of ventilation holes. The first air intake duct 47 has a vent 50 formed in the front portion and a falling wall 51 provided in the upper part of the inside, and air is sucked from the first air intake 49 and the air intake 48. The configuration is such that the outside air (outside air) is detoured in a U shape so that it flows under the falling wall 51 and flows toward the vent 50. The falling wall 51 has an effect of preventing water or the like from entering the first air intake duct 47 from the first air intake port 49 and the air intake port 48 into the vent 50 side. .

  The fan device 6 is attached to the upper part of the rear part of the substrate case 45 so as to be positioned above the circuit board 46. The fan device 6 includes a cooling fan 53 that is a vertical centrifugal fan, a fan motor 54 that rotationally drives the cooling fan 53, and a fan casing 55 that surrounds the cooling fan 53. The fan motor 54 is attached to the upper part of the fan casing 55 by screws 55a, and the rotating shaft 54a faces downward. The upper surface of the fan casing 55 and the lower surface of the partition 16 are spaced apart. The discharge port 56 of the fan casing 55 is directed forward, and the top end portion 56 a of the upper portion of the discharge port 56 is directed upward and is in contact with the lower surface of the partition 16. The cooling fan 53 is configured such that the rotating shaft 54a of the fan motor 54 serving as the rotating shaft of the cooling fan 53 is positioned in front of the first intake port 49 and faces the lower side of the right heating coil 22. Yes.

  An upper suction port 57 having a shape larger than that of the fan motor 54 is formed in the upper portion of the fan casing 55. The upper suction port 57 is located between the cooling fan 53 and the partition 16 and thus the right heating coil 22 and communicates with the vent 50 of the first intake duct 47. When the cooling fan 53 is rotationally driven by the fan motor 54, outside air (cooling air) is sucked into the upper suction port 57 through the first intake duct 47. A path through which the outside air passes is defined as a first intake path 58.

  A lower suction port 59 is formed at a lower portion of the fan casing 55 at a position corresponding to a lower portion of the upper suction port 57. In this case, the fan device 6 is attached to the substrate case 45 in a state in which the lower end portion 6a is spaced upward from the bottom portion 45a of the substrate case 45, and the lower end portion 6a of the fan device 6 and the bottom portion 45a of the substrate case 45 are mounted. The circuit board 46 is arranged between the two.

  A first air duct 60 extending in the front-rear direction is provided at the center in the left-right direction of the front lower portion of the substrate case 45, and the upper portion of the front portion of the substrate case 45 is positioned above the first air duct 60. The second air duct 61 is provided. Among these, the rear part of the 1st ventilation duct 60 is connected to the lower part of the discharge port 56 of the fan casing 55, and the front part is opening. A guide plate 62 is provided at the lower part of the rear part of the first air duct 60. The rear end portion of the upper portion of the guide plate 62 is connected to the lower end portion of the discharge port 56 of the fan casing 55, and the lower end portion of the front portion of the guide plate 62 is in contact with the upper surface of the circuit board 46. In this case, a part of the cooling air discharged from the discharge port 56 of the fan casing 55 flows forward through the first air duct 60.

  A switching element (for example, IGBT) 66a and a heat radiating member 66b of an inverter that generates a large amount of heat among electrical components are disposed in a portion of the circuit board 46 that is located in the first air duct 60. Accordingly, the switching element 66a and the heat radiating member 66b are cooled by the cooling air passing through the first air duct 60.

  The rear part of the second air duct 61 communicates with the upper part of the discharge port 56 of the fan casing 55, and the front part communicates with the communication part 26 of the partition 16. The bottom surface 61 a of the second air duct 61 is an inclined surface that increases from the rear portion toward the communication portion 26. In this case, a part of the cooling air discharged from the discharge port 56 of the fan casing 55 is guided to the communication part 26 through the second air duct 61. A rear partition portion between the first air duct 60 and the second air duct 61 is used as a flow dividing plate portion 63, and the cooling air discharged from the discharge port 56 of the fan casing 55 is cooled by the flow dividing plate portion 63. The first air duct 60 side and the second air duct 61 side are divided.

  Although not shown in detail in the lower part of the substrate case 45, a second air intake path 65 is formed in a state of being separated from the first air duct 60 and the guide plate 62. The rear part of the second intake path 65 communicates with the lower intake port 59 of the fan casing 55, and the front part is connected to the machine via a second intake port (not shown) formed at the bottom of the main body case 2. It communicates with the outside. In the circuit board 46, a part of the electrical component 66 that generates a relatively small amount of heat is disposed in a portion corresponding to the outside of the first air duct 60 and the lower part of the fan casing 55. When the fan device 6 is driven, these electric components are cooled by the cooling air sucked into the fan casing 55 from the lower suction port 59 through the second air intake path 65 through the second air intake port (not shown). It is designed to be cooled.

  Between the front portion of the substrate case 45 and the back surface of the front portion of the main body case 2, an auxiliary plate 70 having an L shape as viewed from above is provided. The auxiliary plate 70 and the front portion of the substrate case 45 are provided. An auxiliary duct 71 is formed by the front wall of the main body case 2 and the front portion of the partition plate 10. The lower portion of the auxiliary duct 71 communicates with the front opening of the first air duct 60, and the cooling air that has passed through the first air duct 60 is discharged to the auxiliary duct 71. Two vent holes 72 made of rectangular holes are formed in the front portion of the partition plate 10 so that the cooling air passing through the auxiliary duct 71 is guided to the left roaster unit 8 side. Yes. A decorative cover 73 is attached to the right part of the front surface of the main body case 2.

  On the bottom surface of the main body case 2, a diaphragm portion 2 a is provided at a position facing the rear portion of the circuit board 46. In addition, an opening 45b (see FIG. 3) is provided at a position facing the aperture 2a at the bottom of the substrate case 45. Although details will be described later, the ground portion of the circuit board 46 and the aperture portion 2a are electrically connected via a substrate-housing connection portion 68. A housing-power supply connection 69 is provided at the rear of the main body case 2. The power lines 67 a and 67 b of the power cord 67 are connected to the rear part of the circuit board 46. The ground wire 67 c of the power cord 67 and the main body case 2 are electrically connected at the casing-power source connection portion 69.

  Although not shown in detail, the housing-power supply connecting portion 69 is fixed by screwing a screw inserted into a hole provided in the main body case 2 into a nut, and a ground wire 67c between the screw and the nut. What is necessary is just to set it as the structure which inserts | pinches the edge part. Further, the three-terminal plug of the power cord 67 is connected to a commercial AC power source (corresponding to an AC power source, indicated by reference numeral 81 in FIG. 4).

  FIG. 3 is an enlarged view showing a part of the configuration of FIG. 2, and shows a detailed configuration of the board-housing connection portion 68. As shown in FIG. 3, a ground connection terminal 76 having a U-shaped cross section is inserted into the through holes 74 and 75 provided in the circuit board 46 from below. The ground connection terminal 76 is electrically connected to the through holes 74 and 75 by, for example, soldering at the leg portions 76a and 76b protruding to the upper surface side of the circuit board 46. The through holes 74 and 75 are electrically connected to a ground portion (details will be described later) of the circuit board 46.

  The lower surface of the bottom portion 76 c of the ground connection terminal 76 is located at the lower end of the opening 45 b of the substrate case 45 and is in contact with the upper surface of the aperture portion 2 a of the main body case 2. A hole is provided in the bottom 76c of the ground connection terminal 76 and the central portion of the throttle portion 2a. A screw 77 (corresponding to a locking member) is inserted into these holes from the lower surface side of the throttle portion 2a. The screw 77 is attached to a nut 78 disposed on the upper surface of the bottom 76c of the ground connection terminal 76. Screwed and fixed.

  With such a configuration, the ground portion of the circuit board 46 and the throttle portion 2a are electrically connected through the opening 45b provided in the board case 45 at a position where the circuit board 46 and the main body case 2 face each other. Yes. In the present embodiment, the ground connection terminal 76 and the nut 78 constitute a locked member. If the hole of the ground connection terminal 76 is a screw hole corresponding to the screw 77, the nut 78 can be omitted.

  FIG. 4 schematically shows the electrical configuration of the induction heating cooker. In FIG. 4, the configuration on the operation panel unit 42 side is omitted. First, the structure regarding the heating coil 21 is demonstrated. An AC input terminal of a rectifier 79 formed by connecting diodes in a bridge shape is connected to a commercial AC power supply 81 via a noise filter circuit 80 and a power cord 67.

  The noise filter circuit 80 includes a resistor R1, capacitors C1 to C4, and a common mode coil L1. Between the AC output terminals 81a and 81b of the commercial AC power supply 81, the resistor R1, the capacitor C1 (line-to-line capacitor), and the input terminals of the common mode coil L1 are connected in parallel to each other via a power cord 67. Between the AC input terminals of the rectifier 79, a series circuit of capacitors C2 and C3 (corresponding to an earth capacitor) and a capacitor C4 (line capacitor) are connected in parallel with each other.

  An interconnection point Ne between the capacitors C2 and C3 corresponds to the ground portion of the circuit board 46, and the interconnection point Ne is electrically connected to the main body case 2. A ground terminal 81 c of a commercial AC power supply 81 is electrically connected to the main body case 2 via a power cord 67. The noise filter circuit 80 having such a configuration is a filter for reducing common mode noise, and is provided to prevent high-frequency noise generated in an inverter circuit 88 to be described later from entering the commercial AC power supply 81 side. .

  The DC output terminal of the rectifier 79 is connected to both terminals of the smoothing capacitor 83 via the reactor 82. Both terminals of the smoothing capacitor 83 are connected to arms composed of IGBTs 86 and 87 as positive and negative switching elements via DC buses 84 and 85. Thereby, a half-bridge type inverter circuit 88 is configured. A reflux diode is connected between each collector and emitter of the IGBTs 86 and 87. One terminal of the heating coil 21 is connected to the output terminal of the inverter circuit 88, and resonance capacitors 89 and 90 are connected between the other terminal of the heating coil 21 and the DC buses 84 and 85. Yes. The inverter circuit 88 having such a configuration is for supplying a high-frequency current to the heating coil 21.

  A current transformer 91 is inserted on the AC input side of the rectifier 79, and a detection signal of the current transformer 91 is supplied to a current detection circuit 92. A current transformer 93 is inserted on the output side of the inverter circuit 88, and a detection signal of the current transformer 93 is supplied to the high frequency current detection circuit 94.

  Since the configuration related to the heating coil 22 is the same as the configuration related to the heating coil 21 described above, the same reference numerals as those of the configuration related to the heating coil 21 are given, and description thereof is omitted. The input voltage detection circuit 95 detects the input voltage to the rectifier 79 via the transformer 96. The control circuit 97 is mainly composed of a microcomputer, which includes signals from the current detection circuit 92, the high-frequency current detection circuit 94, and the input voltage detection circuit 95, and operation of the operation panel unit 42 (not shown). The signal from the unit 40 is given. The control circuit 97 controls the drive of the inverter circuit 88 via the photocoupler 98 and the inverter drive circuit 99 based on the given signal, and causes the display unit 41 of the operation panel unit 42 to perform various displays. It has become.

According to the above configuration, the following operations and effects can be obtained.
In the induction heating cooker of this embodiment, the connection point Ne (the ground portion of the circuit board 46) of the capacitors C2 and C3 constituting the noise filter circuit 80 and the main body case 2 grounded via the ground wire 67c are as follows. The circuit board 46 and the main body case 2 are electrically connected via a board-housing connection portion 68 at a position where the circuit board 46 and the main body case 2 face each other. For this reason, it is possible to connect the interconnection point Ne and the main body case 2 at a short distance. Thereby, the impedance (inductance, high frequency resistance, etc.) between the interconnection point Ne and the main body case 2 can be reduced.

  According to such a configuration, the noise suppression effect by the noise filter circuit 80 can be enhanced without complicating the configuration, and the common mode noise generated in the inverter circuit 88 can be prevented from flowing to the commercial AC power supply 81 side. . That is, electronic components, etc.-floating capacitance-main body case 2- through the stray capacitance between the copper foil wiring (pattern) and electronic components on the circuit board 46 on which the inverter circuit 88 is mounted and the main body case 2. It is possible to prevent common mode noise from propagating through the path of the ground wire 67c, the ground, the commercial AC power supply 81, and the electronic components. Therefore, it is possible to suppress the occurrence of a failure due to noise in other devices connected to the commercial AC power supply 81. That is, the noise terminal voltage of the induction heating cooker can be reduced.

The ground wire 67 c of the power cord 67 and the main body case 2 are electrically connected at a housing-power supply connecting portion 69 provided at a position different from the substrate-housing connecting portion 68. Thus, by setting the position where the interconnection point Ne and the main body case 2 are electrically connected to each other and the position where the main body case 2 and the ground wire 67c (ground) are electrically connected are separated from each other, Since the path for the common mode noise to circulate toward the commercial AC power supply 81 becomes longer, the noise suppression effect by the noise filter circuit 80 can be further enhanced.
The circuit board 46 and the bottom surface of the main body case 2 are configured to be parallel to each other. Thereby, it is possible to suppress an increase in the connection distance between the ground portion of the circuit board 46 and the main body case 2 in the board-housing connection part 68.

  The board-housing connection portion 68 includes a ground connection terminal 76 disposed on the circuit board 46 and electrically connected to the interconnection point Ne, and a throttle portion 2a provided in the main body case 2 as a board case. The ground portion of the circuit board 46 and the main body case 2 are electrically connected by contacting through the opening 45b of 45. That is, the circuit board 46 and the main body case 2 are arranged close to each other. According to such a configuration, the impedance between the interconnection point Ne and the main body case 2 can be further reduced. In addition, the circuit board 46 is shielded by the main body case 2 made of a metal material, and noise generated in the inverter circuit 88 can be prevented from propagating to other parts in the main body case 2.

  Further, a screw 77 is inserted from the bottom surface side of the throttle portion 2a into the bottom portion 76c of the ground connection terminal 76 and the central portion of the throttle portion 2a, and the screw 77 is inserted into the top surface of the bottom portion 76c of the ground connection terminal 76. It was set as the structure fixed by screwing in the nut 78 arrange | positioned in (3). Thereby, the contact state between the ground connection terminal 76 and the narrowed portion 2a can be improved, and the impedance between the interconnection point Ne and the main body case 2 can be further reduced.

  The circuit board 46 was composed of a single printed wiring board. That is, the inverter circuit 88 and the noise filter circuit 80 are mounted on the same printed wiring board. In such a configuration, it becomes difficult to sufficiently electrically separate the inverter circuit 88 and the connection terminal to the commercial AC power supply 81 on the substrate, and common mode noise generated by the inverter circuit 88 is generated on the commercial AC power supply 81 side. The possibility of getting around increases. However, according to the configuration of the present embodiment, the noise suppression effect by the noise filter circuit 80 is enhanced. Therefore, even with such a substrate configuration, it is possible to suppress common mode noise from entering the commercial AC power supply 81 side.

(Second Embodiment)
Hereinafter, a second embodiment of the present invention in which the configuration of the electrical connection between the ground portion of the circuit board 46 and the main body case 2 is changed will be described with reference to FIG. FIG. 5 is a diagram corresponding to FIG. 3 in the first embodiment, and the same parts as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  In the bottom surface portion of the main body case 2, an aperture portion 2 b is provided in a portion where the circuit board 46 does not exist above. A ground connection terminal 103 having an inverted U-shaped cross section is inserted into the through holes 101 and 102 provided in the circuit board 46 from above. The ground connection terminal 103 is electrically connected to the through holes 101 and 102 by, for example, soldering at the leg portions 103a and 103b protruding to the lower surface side of the circuit board 46. The through holes 101 and 102 are electrically connected to the ground portion of the circuit board 46 (interconnection point Ne between the capacitors C2 and C3).

  A conductor 104 is provided on the lower surface of the substrate case 45. The conductor 104 is a plate made of a conductive material. Note that a copper foil pattern may be used as the conductor 104. The conductor 104 is arranged so that one end side faces the throttle portion 2 b and the other end side faces the ground connection terminal 103.

  A hole is provided in the central portion of the upper side portion 103 c of the ground connection terminal 103. In the conductor 104 and the substrate case 45, a hole is also provided at a position facing the central portion of the upper side portion 103 c of the ground connection terminal 103. Screws 105 (corresponding to locking members) are inserted into these holes from the lower surface side of the substrate case 45, and the screws 105 are nuts 106 disposed on the upper surface of the upper side portion 103c of the ground connection terminal 103. It is fixed by being screwed in.

  A support member 107 made of a cylindrical resin is disposed around the screw 105 between the circuit board 46 and the board case 45. With such a configuration, the ground portion of the circuit board 46 and the conductor 104 are electrically connected via the ground connection terminal 103, the screw 105, and the nut 106. In the present embodiment, the ground connection terminal 103 and the nut 106 constitute a locked member. If the hole of the ground connection terminal 103 is a screw hole corresponding to the screw 105, the nut 106 can be omitted.

  A hole is provided in the central portion of the throttle portion 2b. The conductor 104 is also provided with a hole at a position facing the throttle portion 2b. Screws 108 are inserted into these holes from the upper surface side of the throttle portion 2b. The screws 108 are screwed and fixed to nuts 109 provided on the lower surface of the throttle portion 2b. As a result, the lower surface of the conductor 104 and the upper surface of the diaphragm portion 2b are in contact, that is, the conductor 104 and the diaphragm portion 2b are electrically connected.

  The substrate-chassis connection part 110 of the present embodiment configured as described above is provided with the conductor 104 on the lower surface of the substrate case 45 so as to be interposed between the substrate case 45 and the bottom surface part of the main body case 2. . Then, the ground portion (interconnection point Ne) of the circuit board 46 and the main body case 2 were electrically connected via the conductor 104. Even with such a configuration, since the impedance between the ground portion of the circuit board 46 and the main body case 2 can be reduced, the same operations and effects as in the first embodiment can be obtained.

  If the board case 45 is accommodated in the main body case 2 in a state in which the screw 105 is screwed into the nut 106, and then the assembly work is performed so that the screw 108 is screwed into the nut 109, the workability during the assembly is improved. In addition, since the ground connection terminal 103 is arranged to be inserted from the upper surface of the circuit board 46 (component surface arrangement), it can be hardly affected by vibration during transportation.

  By configuring the conductor 104 in a plate shape, the inductance between the ground portion of the circuit board 46 and the main body case 2 can be reduced. If the conductor 104 is made of a nonmagnetic and low resistance material such as aluminum, for example, the skin effect is reduced, so that the high frequency resistance between the ground portion of the circuit board 46 and the main body case 2 can be reduced. Furthermore, the effect of reducing the common mode noise is further enhanced by the portion where the plate-like conductor 104 and the bottom portion of the main body case 2 face each other as a capacitor.

(Other embodiments)
The present invention is not limited to the embodiments described above and illustrated in the drawings, and the following modifications or expansions are possible.
The board-housing connection portion 68 is not limited to the position shown in FIG. 1 and may be provided at a position where the circuit board 46 and the main body case 2 face each other. The method for electrically connecting the ground portion (interconnection point Ne) of the circuit board 46 and the main body case 2 in the substrate-housing connection portion 68 is a method using the throttle portion 2a, the ground connection terminal 76, the screw 77, and the nut 78. Not exclusively. For example, the ground portion of the circuit board 46 and the main body case 2 may be electrically connected using a wire.
The locking member is not limited to a screw, and the locked member is not limited to a ground connection terminal or a nut. For example, the metal member which has a hole as a to-be-latched member may be attached to the circuit board 46, and a metal pin-like member as a locking member may be inserted and inserted into the hole to be locked.

The housing-power supply connecting portion 69 may be provided at a position other than the position where the circuit board 46 and the main body case 2 face each other. The circuit board 46 and the bottom surface portion of the main body case 2 may not be arranged so as to be parallel to each other. For example, the circuit board 46 may be divided into a printed wiring board on which the inverter circuit 88 is mounted and a printed wiring board on which the noise filter circuit 80 is mounted. That is, the circuit board 46 may be composed of a plurality of printed wiring boards.
The inverter circuit 88 is not limited to the half-bridge type, and other configurations such as a full-bridge type may be used. In each said embodiment, although the example which applied this invention to the induction heating cooking appliance which has two IH heating parts (two inverter circuits) was shown, this invention is one IH heating part (one inverter circuit) And an induction heating cooker having three or more IH heating units (three or more inverter circuits). In each of the above-described embodiments, the case where the present invention is applied to a stationary induction heating cooker has been illustrated, but the present invention can also be applied to a built-in induction heating cooker incorporated in a kitchen.

The exploded perspective view of the induction heating cooking appliance which shows the 1st Embodiment of this invention Longitudinal side view along line XX in FIG. The figure which expands and shows the partial structure of FIG. Electrical configuration diagram of induction heating cooker FIG. 3 equivalent view showing the second embodiment of the present invention

Explanation of symbols

  In the drawing, 2 is a main body case (housing), 4 is a top plate, 21 and 22 are heating coils, 45 is a board case, 45b is an opening, 46 is a circuit board (printed wiring board), 67c is a ground wire, 76 , 103 are ground connection terminals (locked members), 77 and 105 are screws (locking members), 78 and 106 are nuts (locked members), 80 is a noise filter circuit, and 81 is a commercial AC power supply (AC power supply). , 88 is an inverter circuit, 104 is a conductor, C2 and C3 are earth capacitors, L1 is a common mode coil, and W is a cooking vessel.

Claims (7)

A top plate on which the cooking container is placed;
A heating coil that is arranged below the top plate and induction-heats the cooking container;
An inverter circuit for receiving a supply of power from an AC power source and supplying a high-frequency current to the heating coil;
A noise filter circuit interposed between the AC power supply and the inverter circuit, and having a common mode coil and an earth capacitor having one terminal connected to a ground potential;
A printed wiring board on which the inverter circuit and the noise filter circuit are mounted;
A substrate case made of an insulating material for accommodating the printed wiring board;
A housing made of a metal material in which the heating coil and the substrate case are accommodated,
The printed wiring board is fixed to the housing via the substrate case,
The housing is grounded via a ground wire,
One terminal of the earth capacitor and the housing are electrically connected at a position where the printed wiring board and the housing face each other,
The induction heating cooker, wherein the casing and the ground wire are electrically connected at a position different from a position where the printed wiring board and the casing face each other.   The induction heating cooker according to claim 1, wherein the printed wiring board is disposed so as to be parallel to the bottom surface of the casing.   The induction heating cooker according to claim 1 or 2, wherein the printed wiring board is composed of one sheet.   The induction heating cooker according to any one of claims 1 to 3, wherein the printed wiring board is disposed at a position close to the casing. The substrate case has an opening,
The induction heating cooker according to any one of claims 1 to 4, wherein one terminal of the earth capacitor and the casing are electrically connected through the opening. A conductor is provided between the substrate case and the housing,
The induction heating cooker according to any one of claims 1 to 5, wherein one terminal of an earth capacitor and the casing are electrically connected via the conductor. A locked member provided on the printed wiring board and electrically connected to one terminal of an earth capacitor;
A locking member that penetrates the substrate case and locks to the locked member;
The induction heating cooking according to any one of claims 1 to 6, wherein one terminal of the earth capacitor and the housing are electrically connected via the locked member and the locking member. vessel.

Images