JP2014060206A - Circuit board unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit board whose EMC is improved and installation place is prevented from being limited to an area of a ground potential.SOLUTION: A circuit board unit includes: an upper case 13 and a lower case 15 which are assembled to each other and which have an inner space surrounded by conductors covered with an insulator; and a substrate on which a circuit equipped with an element generating an electromagnetic interference wave is mounted, which has an area of a ground potential and a ground terminal 23B electrically connected to the area of the ground potential, and which is housed in the space by electrically connecting conductors of the upper case 13 and the lower case 15 to the area of the ground potential.

Description

  The present invention relates to a circuit board unit.

  An inverter circuit using a switching element such as an FET (electrolytic effect transistor) is mounted on the motor drive control device. Since the inverter circuit switches a large current supplied from a vehicle-mounted battery, an electromagnetic interference wave is easily generated during operation.

  Patent Document 1 discloses a motor controller in which EMC (electromagnetic compatibility) is improved by providing a protective wire net that shields electromagnetic interference waves on one side of a circuit board. Further, in Patent Document 2, the EMC is obtained by electrically connecting the ground potential region of the circuit board to a metal case covering one side of the circuit board, and further fixing the case to the ground potential portion of the vehicle. An improved control device is disclosed.

Japanese Patent Laid-Open No. 05-15107 JP 2006-108398 PR

  However, both the motor controller disclosed in Patent Document 1 and the control device disclosed in Patent Document 2 are provided with a metal conductor on one side of the circuit board, and electromagnetic interference from the side where the metal conductor is not provided. There was a problem of insufficient wave shielding.

  In the motor controller disclosed in Patent Document 1, since the protection wire mesh is not grounded, the electrical energy accumulated in the protection wire mesh is re-radiated as an electromagnetic wave outside the protection wire mesh by receiving the electromagnetic interference wave. There was a problem that.

  In addition, the control device disclosed in Patent Document 2 has a problem that the metal case does not have a coating of resin or the like, and the installation location is limited to a region showing the ground potential in the vehicle.

  The present invention has been made in view of the above, and it is an object of the present invention to improve a EMC and to provide a circuit board unit whose installation location is not limited to a ground potential region.

  In order to solve the above-described problem, a circuit board unit according to claim 1 includes a case including a space surrounded by a conductor covered with an insulator except for a part, and an element that generates an electromagnetic interference wave. And a ground potential region and a ground terminal electrically connected to the ground potential region, and a part of the conductor of the case is electrically connected to the ground potential region. And a substrate housed in the space of the case.

  The circuit board unit accommodates a board on which a circuit including an element that generates an electromagnetic interference wave is mounted in a space of a case that forms a space surrounded by a conductor covered with an insulator. When stored, the conductor is electrically connected to the ground potential region of the substrate. Thereby, the electromagnetic interference wave generated from the element on the substrate can be shielded by the conductor of the case.

  The circuit board unit includes a ground terminal that is electrically connected to the ground potential region of the substrate and grounds the conductor of the case via the ground potential region of the substrate. Since the electric energy generated inside the conductor by shielding the interfering electromagnetic wave is released to the outside through the ground terminal, re-radiation of the electromagnetic wave due to the electric energy accumulated in the conductor can be suppressed, and EMC can be improved. .

  In addition, since the case conductor is covered with an insulating material, the circuit board unit is not limited to the ground potential region.

  The circuit board unit according to claim 2 is the circuit board unit according to claim 1, wherein the case includes an upper case and a lower case formed by covering a conductor with an insulator, and the upper case and the case. Each of the lower cases has a protrusion that sandwiches the substrate in the ground potential region as a part of the case, and the conductor of the upper case and the lower case are sandwiched by the protrusion. The conductor and the ground potential region are electrically connected, and the substrate is housed in a space formed by combining the upper case and the lower case.

  According to this substrate unit, the EMC can be improved by covering the substrate with a case made of a conductor, and assembly is facilitated by making the case into a vertically divided type. In addition, according to this substrate unit, the upper case and the lower case each have the protrusions that sandwich the substrate in the ground potential region, so that only the substrate ground potential region is in contact with the substrate inside the case. Can be held in space.

  The circuit board unit according to claim 3 is the circuit board unit according to claim 2, wherein the board has the region of the ground potential at a portion where the protrusion of the upper case and the protrusion of the lower case abut. The protrusions of the upper case and the protrusions of the lower case are exposed at the tops of the protrusions, and the exposed conductors are electrically connected to the ground potential region.

  According to this substrate unit, the conductor is exposed at the top of each of the upper case protrusion and the lower case protrusion, and the exposed conductor is brought into contact with the ground potential region of the substrate. As a result, the conductors of the upper case and the lower case are electrically connected to the ground terminal via the ground potential region of the substrate, and through the ground terminal, the conductors of the upper case and the lower case are shielded by interference electromagnetic waves. The generated electrical energy can be released to the outside.

  The circuit board unit according to claim 4 is the circuit board unit according to claim 2, wherein the protrusion of the upper case, the region of the ground potential of the substrate, and the protrusion of the lower case are formed by a conductive fixture. As a result, the upper case conductor, the lower case conductor, and the ground potential region of the substrate are electrically connected.

  According to this circuit board unit, the board, the upper case, and the lower case can be pressed and fixed together in the area of the ground potential of the board, and assembly is facilitated.

  The circuit board unit according to claim 5 is the circuit board unit according to any one of claims 1 to 4, wherein the ground terminal is connected to a ground potential region of the vehicle.

  According to this circuit board, by connecting the ground terminal to the ground potential region of the vehicle, the electrical energy generated inside the conductors of the upper case and the lower case due to shielding of the disturbing electromagnetic wave can be released to the outside.

It is the schematic which shows the structure of the motor unit using the circuit board unit which concerns on embodiment of this invention. It is sectional drawing which shows an example of a structure of the motor unit using the circuit board unit which concerns on embodiment of this invention. It is a figure which shows an example of fixation with the upper case of a circuit board unit which concerns on embodiment of this invention, a board | substrate, and a lower case. It is a figure which shows an example of the board | substrate which concerns on embodiment of this invention.

  FIG. 1 is a schematic diagram showing a configuration of a motor unit 10 using a circuit board unit according to the present embodiment. The motor unit according to the present embodiment in FIG. 1 is a so-called blower motor unit used for blowing air from an in-vehicle air conditioner as an example.

  The motor unit 10 according to the present embodiment relates to a three-phase motor having an outer rotor structure in which a rotor 12 is provided outside a stator 14. The stator 14 is an electromagnet in which a lead wire is wound around a core member, and constitutes three phases of a U phase, a V phase, and a W phase.

  Each of the U phase, V phase, and W phase of the stator 14 generates a so-called rotating magnetic field by switching the polarity of the magnetic field generated by the electromagnet under the control of the drive control circuit of the motor mounted on the substrate 22.

  A rotor magnet is provided inside the rotor 12, and the rotor magnet rotates the rotor 12 by responding to the rotating magnetic field generated in the stator 14.

  The rotor 12 is provided with a shaft 11 and rotates integrally with the rotor 12. Although not shown in FIG. 1, in this embodiment, the shaft 11 is provided with a multi-blade fan such as a so-called sirocco fan, and the multi-blade fan rotates together with the shaft 11 so It becomes possible.

  The substrate 22 is provided with a heat sink 21 that dissipates heat generated from elements on the substrate 22. The substrate 22 provided with the heat sink 21 is housed in the lower case 15, and is covered with the upper case 13 except for the cooling protrusion 21 </ b> A of the heat sink 21, and the stator 14 is attached to the substrate 22 via the upper case 13.

  The substrate 22 is provided with a fixing portion 22A to which the lower case 15 and the upper case 13 are fixed. The fixing portion 22A is a hole through which a fastener such as a bolt, a rivet, or a clip is passed. Further, a substrate fixing protrusion 15A is provided at a position corresponding to the fixing portion 22A of the lower case 15. Although not shown in FIG. 1, substrate fixing protrusions 13 </ b> A are also provided at positions corresponding to the fixing portions 22 </ b> A of the upper case 13.

  The board 22 is provided with an external connection connector 23 to which electric power is supplied from the in-vehicle battery and a control signal related to the in-vehicle air conditioner is input via a control device such as an ECU (Electronic Control Unit). Yes. Among the terminals constituting the external connection connector 23, the power supply terminal 23A is a terminal to which approximately 12V DC power is supplied from the vehicle-mounted battery. The ground terminal 23B is a grounding terminal connected to the ground potential of the vehicle. Further, the control signal terminal 23C is a terminal to which a control signal related to the vehicle-mounted air conditioner is input.

  In the present embodiment, a substrate 22 provided with a heat sink 21 is housed in a space surrounded by the upper case 13 and the lower case 15, and the substrate 22 is fixed to the upper case 13 and the lower case 15 in this embodiment. This board unit 18 is assumed.

  Next, the configuration of the motor unit 10 incorporating the substrate unit according to the present embodiment will be described with reference to cross-sectional views. FIG. 2 is a cross-sectional view showing an example of the configuration of the motor unit 10 using the circuit board unit according to the present embodiment.

  As shown in FIG. 2, the shaft 11 is provided with a pair of bearings 11A, and the bearings 11A are fixed to the support portion 11B. The shaft 11 is supported rotatably by the bearing 11A with respect to the support portion 11B.

  A coil 14 </ b> A is wound around the stator 14. The coil 14A is provided so as to constitute three phases of a U phase, a V phase, and a W phase whose electrical phases are shifted by 120 degrees. By alternately energizing, a predetermined rotating magnetic field is formed around the stator 14.

  A rotor magnet 12 </ b> A is provided on the inner surface of the rotor 12. The rotor magnet 12A is formed so that one side in the radial direction of the rotor 12 is an N pole and the other side is an S pole.

  The rotor magnet 12A is provided so as to face the stator 14 outside the stator 14 along the radial direction of the rotor 12. When the above-described coil 14A is energized and a rotating magnetic field is formed around the stator 14. Rotational force around the shaft 11 is generated in the rotor magnet 12A due to the interaction between the rotating magnetic field and the magnetic field formed by the rotor magnet 12A, whereby the shaft 11 rotates.

  The stator 14 is installed on the upper case 13. The upper case 13 is combined with the lower case 15 to form a space for housing the substrate 22, and the substrate 22 is fixed by the substrate fixing protrusion 13 A of the upper case 13 and the substrate fixing protrusion 15 A of the lower case 15.

  The upper case 13 is a conductor 13B covered with an insulator, and the lower case 15 is a conductor 15B covered with an insulator. The conductors 13B and 15B are for shielding electromagnetic interference radiated from the elements mounted on the substrate 22, and mainly press the conductors formed of a metal such as copper, brass, iron or aluminum. Molded ones are used. In addition to metals, non-metals that have conductivity and can shield electromagnetic interference such as conductive resins or pitch-based carbon fibers may be used.

  On the substrate 22, on the side opposite to the side where the heat sink 21 for heat dissipation is provided, elements such as FETs 41 C and 41 F, capacitors 42 D and 42 E related to switching of power supplied to the stator 14, and these elements are controlled. A microcomputer (CPU) 31 is mounted.

  The power controlled by the switching of the FETs 41C, 41F, etc. is supplied to the stator 14 via the power supply terminal 24B.

  In FIG. 2, a bracket 51 (not shown in FIG. 1) is fixed to the upper case 13 via a fixing bolt 53. The bracket 51 has a plurality of leg portions 51A to which a fixing tool such as a bolt can be applied on the outer peripheral portion, and is a member for fixing the motor unit 10 at a predetermined position by the fixing tool.

  FIG. 3 is a diagram showing an example of fixing the upper case 13, the substrate 22, and the lower case 15 of the circuit board unit according to the embodiment of the present invention. FIG. 3A is a diagram illustrating an example of the arrangement of conductors in the upper case 13, the substrate fixing protrusion 13A, the lower case 15, and the substrate fixing protrusion 15A.

  The board fixing protrusion 13A is provided with a conductor 13B continuously from the upper case 13, and the board fixing protrusion 15A is provided with a conductor 15B continuously from the lower case 15.

  FIG. 3B is a diagram illustrating an example of a manner in which the substrate 22, the upper case 13, and the lower case 15 are secured to ensure electrical connection between the ground potential region of the substrate 22 and the conductors 13 </ b> B and 15 </ b> B. .

  As shown in FIG. 3B, a fixing sleeve 22A of the substrate 22 is provided with a conductor sleeve 22B electrically connected to the ground potential region of the substrate, and a conductive fastener such as a metal fixing bolt 54 is provided. Then, the lower case 15, the substrate 22, and the upper case 13 are fastened together. The portions of the board fixing projections 13A and the board fixing projections 15A that are in contact with the fixing bolts 54 expose the conductors. As a result, the sleeve 22 </ b> B and the conductor 15 </ b> B showing the ground potential in the conductor 13 </ b> B and the substrate 22 are electrically connected via the fixing bolt 54. In the present embodiment, instead of the sleeve 22B, a circuit pattern of a ground potential region covering the side surface of the hole of the fixing portion 22A of the substrate 22 may be provided.

  The conductors 13B and 15B are exposed at the top end surface 13C of the substrate fixing protrusion 13A and the top end surface 15C of the substrate fixing protrusion 15A, respectively, and the exposed conductors 13B and 15B are connected to the ground potential region of the substrate 22. You may make it contact.

  Subsequently, the substrate 22 of the circuit board unit according to the present embodiment will be described with reference to FIG. FIG. 4 is a diagram illustrating an example of the substrate 22 according to the present embodiment.

  FIG. 4A is a plan view of the substrate 22 on the side on which the stator 14 is attached. A heat sink 21 is attached to the substrate 22, and the heat sink 21 is provided with a plurality of pin-shaped cooling projections 21 A for heat dissipation.

  4A, near the center of the substrate 22, power supply terminals 24A, 24B, and 24C that supply power to the U phase, V phase, and W phase of the stator 14 are provided.

  4B is a side view of the substrate 22, and FIG. 4C is a plan view of the substrate 22 showing a surface opposite to the side on which the stator 14 is attached.

  In FIG. 4C, an inverter circuit 40 for controlling power supplied to the U phase, V phase, and W phase of the stator 14 is mounted on the substrate 22. The inverter circuit 40 of the substrate 22 according to the present embodiment is a voltage source inverter that operates as a voltage source by connecting large-capacitance capacitors 42A, 42B, 42C, and 42D in parallel to a DC side circuit.

  The inverter circuit 40 includes FETs 41A, 41B, 41C, 41D, 41E, and 41F as switching elements. The FETs 41A and 41D switch the power supplied to the U phase, the FETs 41B and 41E switch to the V phase, and the FETs 41C and 41F switch to the W phase.

  The inverter circuit 40 on the substrate 22 is provided with a coil 43 for removing noise, as well as a reverse connection prevention FET 44 and a large-capacitance capacitor 42E for circuit protection. A microcomputer 31 for controlling the inverter circuit 40 is mounted on the substrate 22.

  The substrate 22 is provided with ground potential regions 26A, 26B, and 26C whose potential is the ground potential. In FIG. 4A, for example, the ground potential region 26A is provided around the pair of fixing portions 22A, and the region around one fixing portion 22A and the region around the other fixing portion 22A are continuous. It is electrically connected by being composed of a circuit pattern. The ground potential region 26 </ b> A is electrically connected to the ground terminal 23 </ b> B of the external connection connector 23.

  In FIG. 4C, for example, ground potential regions 26B and 26C are provided around the pair of fixed portions 22A.

  In the ground potential region 26B and the ground potential region 26C, the circuit pattern is not continuous on the side shown in FIG. However, if possible in the configuration of the substrate, the ground potential region 26B and the ground potential region 26C may be connected by a circuit pattern. Furthermore, the ground potential regions 26B and 26C and the ground terminal 23B may be connected on the side shown in FIG.

  When the fixing portion 22A of the substrate 22, the substrate fixing protrusion 13A of the upper case 13, and the substrate fixing protrusion 15A of the lower case 15 are fixed, the conductor 13B of the upper case 13 and the conductor 15B of the lower case 15 are grounded. The terminal 23B is electrically connected via the ground potential regions 26A, 26B, and 26C of the substrate 22.

  The conductors 13B and 15B accumulate electrical energy by shielding electromagnetic interference radiated from elements on the substrate 22, but in the present embodiment, the accumulated electrical energy is transmitted via the ground terminal 23B. It can be discharged to the outside, for example, the ground potential region of the vehicle.

  The path for discharging the stored electrical energy can be arbitrarily routed from the ground terminal 23B, and the upper case 13 and the lower case 15 are each covered with an insulator, so that the substrate according to the present embodiment The unit is not limited to an area where the installation location is ground potential.

  As described above, according to the present embodiment, a board on which a circuit having a plurality of elements that generate electromagnetic interference waves is mounted is housed in a case made of a conductor covered with an insulator. The electromagnetic interference generated from the upper element can be shielded by the conductor of the case.

  According to the present embodiment, since the conductor is covered with the insulator in the case, the installation location is not limited to the ground potential region. In addition, since the electrical energy accumulated in the conductor of the case can be released to the outside through the ground potential region of the substrate and the terminal of the substrate, re-radiation of electromagnetic waves due to the electrical energy accumulated in the conductor can be suppressed, and EMC Can be improved.

  In this embodiment, the case for storing the substrate is composed of an upper case and a lower case. However, the case is an envelope formed of a conductor covered with an insulator, for example, and the conductor of the envelope is the ground potential of the substrate. The substrate may be stored in the envelope by being electrically connected to the region.

DESCRIPTION OF SYMBOLS 10 ... Motor unit, 11 ... Shaft, 11A ... Bearing, 11B ... Support part, 12 ... Rotor, 12A ... Rotor magnet, 13 ... Upper case, 13A ... Substrate fixing projection, 13B ... conductor, 13C ... end face, 14 ... stator, 14A ... coil, 15 ... lower case, 15A ... substrate fixing projection, 15B ... conductor , 15C ... end face, 18 ... substrate unit, 21 ... heat sink, 21A ... cooling projection, 22 ... substrate, 22A ... fixing part, 22B ... sleeve, 23 ... External connector, 23A: power supply terminal, 23B: ground terminal, 23C: control signal terminal, 24A, 24B, 24C ... power supply terminal, 26A, 26B, 26C: ground Potential region, 31 ... Microcomputer, 40 ... inverter circuit, 41A, 41B, 41C, 41D, 41E, 41F ... FET, 42A, 42B, 42C, 42D, 42E ... capacitor, 43 ... coil, 44 ... reverse connection Prevention FET, 51 ... Bracket, 51A ... Leg, 53 ... Fixing bolt, 54 ... Fixing bolt

Claims (5)

A case with a space surrounded by a conductor covered with an insulator except for a part,
A circuit including an element that generates an electromagnetic interference wave is mounted, and has a ground potential region and a ground terminal electrically connected to the ground potential region. A part of the case is included in the ground potential region. A substrate that is electrically connected to be housed in the space of the case;
Circuit board unit including. The case consists of an upper case and a lower case formed by covering the conductor with an insulator,
The upper case and the lower case each have a protrusion that sandwiches the substrate in the ground potential region as a part of the case, and the conductor of the upper case is sandwiched by the protrusion. The conductor of the said lower case and the area | region of the said grounding potential are electrically connected, and the said board | substrate is accommodated in the space formed by combining the said upper case and the said lower case. Circuit board unit. The substrate has a region of the ground potential at a portion where the protruding portion of the upper case and the protruding portion of the lower case abut,
3. The circuit board according to claim 2, wherein the protrusions of the upper case and the protrusions of the lower case are exposed at the tops thereof, and the exposed conductors are electrically connected to the ground potential region. unit.   The protrusion of the upper case, the ground potential region of the substrate, and the protrusion of the lower case are pressed and fixed by a conductive fixture, so that the conductor of the upper case and the lower case are fixed. The circuit board unit according to claim 2, wherein a conductor of the case is electrically connected to the ground potential region of the board.   The circuit board unit according to claim 1, wherein the ground terminal is connected to a ground potential region of a vehicle.

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