JP4479522B2 - Electronic equipment - Google Patents

Description

The present invention relates to an electronic device using the wiring structure of the wiring connected to the opposing circuit board.

  Conventionally, hydraulic power steering for assisting the steering operation of the vehicle is known, but in recent years, electric power steering (EPS) in which steering is driven by a motor instead of hydraulic pressure has appeared.

  In such an EPS, an electronic device for driving a motor mounted on a steering part has an electric circuit on which a switching element for driving the motor is incorporated on the board, and the switching element is emitted from the switching element on the outer edge of the board. A heat sink that releases the generated heat is fixed.

  However, it has been found that the electronic device structure as described above has insufficient cooling of the switching element. Therefore, in order to further improve the heat dissipation of the switching element, a dedicated metal substrate on which the switching element is mounted is prepared, and an electronic device having a three-dimensional structure is manufactured.

  Such an electronic device having a three-dimensional structure includes a first board having an electric circuit that generates and outputs a drive signal for driving a steering by a motor, and inputs electric power and a drive signal from the first board to the motor. A second substrate provided with a switching element for outputting a drive signal is housed in a case. These first and second substrates are arranged so that the surfaces on which the electric circuits are installed face each other.

  And the electrical connection with the said 1st board | substrate and the 2nd board | substrate is achieved by the bus bar which is metal wiring. This bus bar is formed, for example, by pressing a metal plate. Such an end of the bus bar is connected between the first substrate and the second substrate, whereby the first substrate and the second substrate are electrically connected.

  However, in the above conventional technique, when the bus bar for supplying power and the bus bar for ground are connected between the first substrate and the second substrate, respectively, the bus bar and the wiring in each substrate are used to connect each substrate. A loop is formed in the space, and a leakage magnetic field, that is, a radiation magnetic field is generated from the loop according to the direction of the flowing current.

  Since a high-frequency large current for supplying power to the switching element flows through these power supply and ground bus bars, a strong radiating magnetic field corresponding to the large current is generated from the loop.

  The space between the substrates has nothing to block the radiated magnetic field. Therefore, this radiated magnetic field leaks to the outside from the connector portion of the case housing the electronic device. The radiated magnetic field leaking from the case in this way affects, for example, the in-vehicle radio (particularly the AM band).

  A loop is also formed by the bus bar that outputs a switching signal to the motor. However, since the current flowing through the bus bar is smaller than the current flowing through the power source and the ground, for example, the influence of the radiated magnetic field on the radio is affected. Is small.

  Also, because the bus bar has inductance, when the switching current flows through the bus bar, the current source is lost when switching the current, and a surge occurs, destroying the elements forming the electric circuit and the electric circuit itself. There is a possibility.

In view of the above points, and an object thereof is to provide an electronic device using the wiring structure capable of reducing the radiation field and inductance.

In order to achieve the above object, according to the first aspect of the present invention, the first bus bar (50) and the second bus bar (60) have portions that are parallel to each other, and between the portions that are parallel to each other. The distance is smaller than at least one of the distance between the first connection point and the second connection point and the distance between the third connection point and the fourth connection point, and flows to the first bus bar. A wiring structure in which the direction of current and the direction of current flowing in the second bus bar are reversed is applied, and the switching elements (31 to 34) mounted on the second substrate are power supplies mounted on the first substrate. Electric power is supplied from the capacitor (23) via the terminal, the first bus bar, and the second bus bar. The wiring provided on the first substrate, the wiring provided on the second substrate, and the first bus bar , And the second busbar The surface of the loop (LP) having the largest area formed by projecting onto an arbitrary surface perpendicular to the substrate and the surface of the opening (12) for the connector in the case are in a vertical positional relationship. It is characterized in that there.

  In this way, the distance between the portions where the bus bars are parallel to each other is made smaller than between the connection points provided on each substrate. Thereby, the area of the loop formed by the first bus bar, the second bus bar, the first substrate, and the second substrate can be reduced. Therefore, the radiation magnetic field leaking from the surface of the loop can be reduced.

Further, the first bus bar and the second bus bar are made parallel to each other and the distance between them is further reduced, thereby generating mutual inductance so that the self-inductance of each bus bar is eliminated by the mutual inductance. Thereby, the inductance of the whole loop can be reduced. Therefore, even if the power supplied to each bus bar is switched at a high frequency, it is possible to prevent the occurrence of an overvoltage, that is, a surge that occurs when switching the current. Using such a wiring structure, the first substrate and the second substrate are electrically connected. As a result, an electronic device free from leakage of the radiated magnetic field can be provided, and for example, the in-vehicle radio can be prevented from being affected by the radiated magnetic field. Further, the surface of the loop and the surface of the opening are in a vertical positional relationship. Thereby, the direction of the radiation magnetic field leaking from the surface of the loop can be made parallel to the surface of the opening. Therefore, the radiant magnetic field leaking from the surface of the loop can be prevented from leaking outside through the opening of the case.

  In the invention according to claim 2, in the first bus bar and the second bus bar, the distance between the parts parallel to each other is the distance between the first connection point and the second connection point, the third connection point and the second bus bar. When the distance between the four connection points is smaller than at least one of the distances, at least one of the first bus bar and the second bus bar is in parallel with at least one of the first substrate and the second substrate. It is characterized by.

  In this way, each bus bar is brought close to and parallel to the substrate. Thereby, the area of the loop formed by each substrate and each bus bar can be reduced. In addition, mutual inductance between the wiring in each substrate and each bus bar can be generated, and the inductance of the bus bar can be reduced.

  In the invention according to claim 3, the first substrate and the second substrate are provided with a conductor layer on the surface or inside thereof, and the first bus bar and the second bus bar are close to the first substrate or the second substrate. And the direction of the current flowing in the parallel part and the direction of the current flowing in the conductor layer provided on the first substrate or the second substrate are arranged to be opposite to each other. Yes.

  Thus, the direction of the current flowing through the first bus bar and the second bus bar and the direction of the current flowing through the conductor layers of the first substrate and the second substrate are arranged in opposite directions. As a result, mutual inductance can be generated and inductance can be reduced by eliminating the inductance of each bus bar.

In the invention according to claim 4 , the first bus bar and the second bus bar have portions that are parallel to each other, and the distance between the portions that are parallel to each other is such that the first connection point and the second connection point are The distance between the third connection point and the distance between the third connection point and the fourth connection point, and the direction of the current flowing in the first bus bar and the direction of the current flowing in the second bus bar And the wiring provided on the first substrate, the wiring provided on the second substrate, the first bus bar, and the second bus bar are each projected onto an arbitrary surface perpendicular to the first substrate. The surface of the loop (LP) having the largest area and the surface of the opening (12) for the connector in the case have a vertical positional relationship.

  Thereby, mutual inductance is produced by the portions where the bus bars are parallel to each other, and the self-inductance of each bus bar can be reduced. In addition, since the loop surface having the largest area formed by each wiring or each bus bar and the surface of the connector opening are in a vertical relationship, it is possible to prevent the radiation magnetic field generated from the loop from leaking from the opening.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. The electronic device shown in the present embodiment drives a motor, for example, in electric power steering of a vehicle.

  FIG. 1 is an overall schematic cross-sectional view of an electronic device according to an embodiment of the present invention. FIG. 2 is an overall circuit diagram of the electronic device shown in FIG. As shown in FIG. 1, the electronic device includes a case 10, a first substrate 20, a second substrate 30, a heat sink 40, a first bus bar 50, a second bus bar 60, and a connector 70. Has been.

  The case 10 forms the outer shape of the electronic device and is made of, for example, a metal containing iron. The case 10 also serves to prevent leakage of a radiated magnetic field, which will be described later, to the outside.

  The first substrate 20 is a printed circuit board that includes an electric circuit that outputs a voltage, a signal, and the like to a second substrate 30 described later. Specifically, as shown in FIG. 2, a drive circuit 21 that generates and outputs a switching signal in response to a command from an ECU (not shown) is provided. The drive circuit 21 receives information on the torque and rotation speed of the motor MO from a microcomputer (not shown) installed on the first substrate 20, and generates and outputs a switching signal according to these parameters.

  In addition, a π-type filter 22 is provided on the first substrate 20. The π-type filter 22 employs a power supply capacitor 23, which eliminates delay in power supply of the battery PW and makes the voltage supplied from the battery PW constant. As such a power supply capacitor 23, for example, an electrolytic capacitor is employed. The drive circuit 21 and the π-type filter 22 correspond to the electric circuit of the present invention.

  The second substrate 30 is a substrate on which switching elements 31 to 34 for driving the motor MO that assists the rotation of the steering are mounted. The second substrate 30 is made of, for example, a metal plate of Al (aluminum) in order to absorb heat generated from the switching element 31. In the present embodiment, the switching elements 31 to 34 are prepared as discrete components in which, for example, a MOSFET is formed, and are installed on the second substrate 30 so that the back surface is in contact with the surface of the second substrate 30. .

  In the first and second substrates 20 and 30, a conductor layer is formed on the surface or inside thereof. Here, the conductor layer refers to wiring constituting a circuit or plate-shaped wiring such as solid GND. That is, in the present embodiment, the conductor layer is a general term for wiring through which current flows.

  The switching elements 31 to 34 receive power from the π-type filter 22 of the first substrate 20 via first and second bus bars 50 and 60 (to be described later), and receive a switching signal from the drive circuit 21 via a bus bar (not shown). input. The back surfaces of the switching elements 31 to 34 are fixed to the second substrate 30 by soldering, and heat generated from the switching elements 31 to 34 is absorbed by the second substrate 30.

  The heat sink 40 is a known heat radiating member made of metal. For example, Al is adopted for such a heat sink 40. In the heat sink 40, the area of the surface on which the second substrate 30 is installed is larger than the area of the second substrate 30, and the second substrate 30 is fixed to one side surface by screws.

  As shown in FIG. 1, the end portion 11 of the case 10 is caulked and fixed on the opposite side of the heat sink 40 from the second substrate 30, so that the heat sink 40 is exposed from the case 10. Thereby, the heat generated from the switching elements 31 to 34 can be released to the outside of the case 10 via the second substrate 30 and the heat sink 40.

  The electrical connection between the substrates 20 and 30 is achieved by a bus bar formed as a wiring by, for example, pressing a metal plate. In the present embodiment, the first and second bus bars 50 and 60 relating to the power source of the battery PW will be described in particular.

  The drive circuit 21 provided on the first substrate 20 and the switching elements 31 to 34 installed on the second substrate 30 are also electrically connected by a bus bar. Further, the switching elements 31 to 34 and the first substrate are connected to each other. The electrical connection with 20 is also made by bus bars, but these bus bars are omitted.

  As described above, the first and second bus bars 50 and 60 are wirings for electrical connection between the first substrate 20 and the second substrate 30. Such first and second bus bars 50, 60 are formed by forming a base material of, for example, Cu (copper) and plating the surface. As shown in FIG. 1, the first and second bus bars 50 and 60 are arranged in a space between the substrates 20 and 30, and the end portions thereof are soldered to the substrates 20 and 30. ing.

  In the present embodiment, the first bus bar 50 functions as a positive electrode of the battery PW, and the second bus bar 60 functions as a negative electrode of the battery PW.

  The connector 70 is fixed to the substrate 20 and serves as an interface with an external circuit. A plurality of L-shaped terminals 24 that are electrically connected to the first substrate 20 are fixed to the connector 70. When an external wiring connector is connected to the connector 70, the external wiring is electrically connected to the microcomputer or the π-type filter 23 provided on the first substrate 20 via the terminal 24. The above is the configuration of the electronic device according to the present embodiment.

  Next, the form of the first and second bus bars 50 and 60 will be described in detail. FIG. 3 is a view showing only the first and second substrates 20 and 30 and the first and second bus bars 50 and 60 in FIG.

  As shown in FIG. 3, the linear first bus bar 50 used as a positive electrode is connected to each of the substrates 20 and 30 in a vertical direction. On the other hand, the second bus bar 60 includes a first straight portion 61, a second straight portion 62, and a third straight portion 63, and each of these sides has a U-shape. The first straight portion 61 of the second bus bar 60 is parallel to the surface of the first substrate 20, the second straight portion 62 is parallel to the first bus bar 50, the third straight portion 63 is parallel to the surface of the second substrate 30, and The end portions of the first straight portion 61 and the third straight portion 63 are connected to the substrates 20 and 30 so as to be close to each other.

  As shown in FIG. 3, the first board 20, the first bus bar 50, the second board 30, and the second bus bar 60 are arranged between the boards 20 and 30 according to the form and arrangement of the bus bars 50 and 60 as described above. Is formed as one loop LP. As shown in FIG. 3, the loop LP is formed by projecting each substrate 20, 30 and each bus bar 50, 60 onto a plane perpendicular to each substrate 20, 30. Here, the area of the region surrounded by the loop LP (the region indicated by the oblique lines in FIG. 3) is referred to as a loop area LS.

  In the present embodiment, as described above, the substrates 20 and 30 and the bus bars 50 and 60 are arranged in parallel and close to each other. For this reason, the loop area LS can be reduced. Thereby, the radiation magnetic field generated from the loop LP can be reduced by forming the loop LP.

  Also, the first bus bar 50 and the second straight portion 62 of the second bus bar 60 are close to each other, and the first and third straight portions 61 and 63 of the second bus bar 60 and the wirings in the respective substrates 20 and 30 (conductor layer). ) Are close to each other. Here, mutual inductance is generated by the current flowing through the first bus bar and the direction of the current flowing through the second bus bar. Further, mutual inductance is generated by the current flowing through the bus bars 50 and 60 and the current flowing through the conductor layers of the substrates 20 and 30. At this time, the direction of the current flowing through the first bus bar 50 and the direction of the current flowing through the second bus bar 60 are opposite to each other. In addition, the direction of the current flowing through the first straight line portion 61 and the third straight line portion 63 of the second bus bar 60 that are parallel to each other close to the substrates 20 and 30, and the current flowing through the conductor layers of the substrates 20 and 30. The directions are opposite to each other. As a result, the self-inductance of each bus bar 50, 60 is eliminated by the mutual inductance. As a result, the inductance of the entire loop LP can be reduced, and the occurrence of overvoltage, that is, surge, which occurs when switching the switching current supplied to the switching elements 31 to 34 can be prevented.

  Subsequently, a relationship between a surface formed by the loop LS (hereinafter referred to as a loop surface) and the opening surface of the opening 12 of the case 10 will be described. First, as shown in FIG. 1, the loop surface is parallel to the xy plane. On the other hand, in the case 10, an opening 12 is provided at a place where the connector 70 is installed. The opening surface of the opening 12 of the case 10 is parallel to the yz plane as shown in FIG.

  Therefore, in this embodiment, the loop surface and the opening surface have a vertical relationship. That is, since the direction of the radiated magnetic field leaking from the loop surface is parallel to the opening surface, the radiating magnetic field can be prevented from leaking from the opening surface. Further, as shown in FIG. 1, by arranging the loop surface at a position farther from the opening surface, the radiated magnetic field leaking from the loop LP is kept away from the opening surface, and the radiated magnetic field is generated outside the case 10. I try not to leak.

  The closer the angle formed between the loop surface and the opening surface is, the more the radiated magnetic field leaking from the loop surface can be prevented from leaking from the opening surface, and the angle formed between the loop surface and the opening surface should be vertical. Most preferred.

  Subsequently, the operation of the EPS in the electronic device shown in FIGS. 1 and 2 will be described. First, a power supply for the battery PW and a command for assisting the rotation of the steering are input to the circuit on the first substrate 20 from the outside via the connector 70. The power source of the battery PW is input to the switching elements 31 to 34 on the second substrate 30 via the π-type filter 22 on the first substrate 20 and the bus bars 50 and 60. Further, a microcomputer (not shown) on the first substrate 20 that has received a command from the ECU generates and outputs a switching signal in accordance with a signal for driving the motor MO input from the ECU.

  The switching signal output from the drive circuit 21 is input to the switching elements 31 to 34 on the second substrate 30 via a bus bar (not shown). And the output according to a switching signal in the switching elements 31-34 is input into the motor MO installed in the steering via the bus bar which is not shown in figure, the 1st board | substrate 20, and a connector. Thus, the steering is driven by the motor MO.

  As described above, in the present embodiment, the distance between the portions where the bus bars 50 and 60 are parallel to each other is made smaller than between the connection points provided on the substrates 20 and 30. . Thereby, the area of the loop LP formed by the first bus bar 50, the second bus bar 60, the first substrate 20, and the second substrate 30 can be reduced. Therefore, the radiation magnetic field leaking from the surface of the loop LP can be reduced.

  Further, the bus bars 50 and 60 are brought close to the substrates 20 and 30 in parallel. Thereby, the area of the loop LP formed by the substrates 20 and 30 and the bus bars 50 and 60 can be reduced. Further, mutual inductance between the wirings of the substrates 20 and 30 and the bus bars 50 and 60 can be generated. Thereby, the inductance of each bus-bar 50 and 60 can be reduced, and generation | occurrence | production of a surge can be prevented by extension.

  By using the above wiring structure, it is possible to provide an electronic device with a small leakage of the radiated magnetic field, and it is possible to prevent the vehicle-mounted radio from being affected by the radiated magnetic field.

(Second Embodiment)
In the present embodiment, only different parts from the first embodiment will be described. FIG. 4 is a diagram showing only the first and second substrates 20 and 30 and the first and second bus bars 50 and 60 in the second embodiment.

  In the present embodiment, the second bus bar 60 is formed of only the first straight portion 61 and the second straight portion 62, and has an L shape. Specifically, one end of the second straight portion 62 of the second bus bar 60 is bonded to the second substrate 30, and the second straight portion 62 is in parallel with and close to the first bus bar 50. ing. Further, the first straight portion 61 joined perpendicularly to the second straight portion 62 is in a state of being parallel and close to the first substrate 20, and one end thereof is joined to the first substrate 20. ing. Such a second bus bar 60 may be used.

(Third embodiment)
In the present embodiment, only parts different from the first and second embodiments will be described. FIG. 5 is a diagram showing only the first and second substrates 20 and 30 and the first and second bus bars 50 and 60 in the third embodiment.

  In the present embodiment, the second bus bar 60 is formed by only the second straight portion 62 and the third straight portion 63, and has an L shape as in the second embodiment. Specifically, one end of the second straight portion 62 of the second bus bar 60 is joined to the first substrate 20, and the second straight portion 62 is in parallel with and close to the first bus bar 50. ing. Further, the third linear portion 63 joined perpendicularly to the second linear portion 62 is in a state of being parallel and close to the second substrate 30, and one end thereof is joined to the second substrate 30. ing. Such a second bus bar 60 may be used.

(Other embodiments)
Each of the substrates 20 and 30 and each of the bus bars 50 and 60 shown in FIGS. 1 and 3 is drawn two-dimensionally, but each of the bus bars 50 and 60 used in an actual electronic device has a three-dimensional structure. There may be. For this reason, in FIG. 1 and FIG. 3, each bus bar 50, 60 may have a straight line portion extending in the direction perpendicular to the paper surface.

  In the first to third embodiments, only the form of the bus bars 50 and 60 related to the power supplied from the battery PW has been described. For example, the drive circuit 21 on the first board 20 and the second board 30 are provided. Even when electrical connection with the switching elements 31 to 34 is performed by the bus bar, the bus bar may be connected between the first substrate 20 and the second substrate 30 so that the bus bars are parallel and close to each other.

  Furthermore, in the said 1st-3rd embodiment, although the 1st bus bar 50 is comprised only by the linear part, this 1st bus bar is comprised including a some linear part like the 2nd bus bar 60. A thing may be adopted. Even in such a case, the first bus bar 50 is connected between the first substrate 20 and the second substrate 30 so as to be parallel to and close to the second bus bar 6.

1 is an overall schematic cross-sectional view of an electronic device according to an embodiment of the present invention. FIG. 2 is an overall circuit diagram of the electronic device shown in FIG. 1. In FIG. 1, it is the figure which showed only the 1st, 2nd board | substrate and the 1st, 2nd bus bar. In 2nd Embodiment, it is the figure which showed only the 1st, 2nd board | substrate, and the 1st, 2nd bus bar. In 3rd Embodiment, it is the figure which showed only the 1st, 2nd board | substrate and the 1st, 2nd bus bar.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Case, 12 ... Opening part, 20 ... 1st board | substrate, 21 ... Drive circuit,
22 ... π-type filter, 23 ... Power supply capacitor, 24 ... Terminal, 30 ... Second substrate,
31-34 ... switching element, 40 ... heat sink, 50 ... first bus bar,
60 ... second bus bar, 70 ... connector.

Claims (4)

A first substrate (20) having an electric circuit (21, 22) that is supplied with power through the terminal (24) and driven by the power;
A second substrate (30) disposed to face the first substrate and electrically connected to the electrical circuit;
A first bus bar (50) configured as a plate-like wiring, having one end connected to the first substrate, the other end connected to the second substrate, and supplying the power from the first substrate to the second substrate. And a second bus bar (60),
A first connection point and a second connection point are provided on the first substrate, a third connection point and a fourth connection point are provided on the second substrate, and the first bus bar is connected to the first connection point. Connected between the third connection point, the second bus bar is connected between the second connection point and the fourth connection point,
The first bus bar and the second bus bar have portions that are parallel to each other, and a distance between the portions that are parallel to each other is a distance between the first connection point and the second connection point. The distance between the third connection point and the fourth connection point is smaller than the distance between the third connection point and the fourth connection point. The direction of the current flowing through the first bus bar and the direction of the current flowing through the second bus bar Is an electronic device to which the wiring structure is applied in the reverse direction and assists the operation of the steering by driving a motor (MO) provided in the steering of the vehicle,
The first substrate includes a power supply capacitor (23) to which power is supplied from a power supply (PW), and a drive circuit (21) that generates a switching signal in response to an external command via the terminal. And
The second substrate is provided with switching elements (31 to 34) for driving the motor by outputting a switching voltage corresponding to the switching signal, on a surface opposite to the surface on which the switching element is installed. The heat sink (40) is fixed,
The first board, the second board, and the heat sink are housed in a case (10). The case is provided with an opening (12) and a connector (70) for housing the terminals. ,
The switching element is configured such that electric power is supplied from the power supply capacitor via the terminal, the first bus bar, and the second bus bar,
It is formed by projecting the wiring provided on the first substrate, the wiring provided on the second substrate, the first bus bar, and the second bus bar onto arbitrary surfaces perpendicular to the first substrate, respectively. An electronic device characterized in that the surface of the loop (LP) having the largest area and the surface of the opening (12) for the connector in the case are in a vertical positional relationship. In the first bus bar and the second bus bar, the distance between the parallel parts is a distance between the first connection point and the second connection point, and the third connection point and the fourth connection. When the distance between the first bus bar and the second bus bar is smaller than at least one of the distances between the points, the at least one of the first bus bar and the second bus bar is in parallel with at least one of the first substrate and the second substrate The electronic device according to claim 1. The first substrate and the second substrate are provided with a conductor layer on the surface or inside thereof,
The first bus bar and the second bus bar are provided on the first substrate or the second substrate, and the direction of the current flowing through the first substrate or the portion parallel to the second substrate. The electronic device according to claim 2, wherein the electronic devices are arranged so that directions of currents flowing in the conductor layers are opposite to each other. A first substrate (20) having an electric circuit (21, 22) that is supplied with power through the terminal (24) and driven by the power;
A second substrate (30) disposed to face the first substrate and electrically connected to the electrical circuit;
A first bus bar (50) configured as a plate-like wiring, having one end connected to the first substrate, the other end connected to the second substrate, and supplying the power from the first substrate to the second substrate. And a second bus bar (60),
A first connection point and a second connection point are provided on the first substrate, a third connection point and a fourth connection point are provided on the second substrate, and the first bus bar is connected to the first connection point. Connected between the third connection point, the second bus bar is connected between the second connection point and the fourth connection point,
The first bus bar and the second bus bar have portions that are parallel to each other, and a distance between the portions that are parallel to each other is a distance between the first connection point and the second connection point. , The distance between the third connection point and the fourth connection point is smaller than at least one of the distances, and the direction of the current flowing through the first bus bar and the direction of the current flowing through the second bus bar And are in the opposite direction,
It is formed by projecting the wiring provided on the first substrate, the wiring provided on the second substrate, the first bus bar, and the second bus bar onto arbitrary surfaces perpendicular to the first substrate, respectively. An electronic device characterized in that the surface of the loop (LP) having the largest area and the surface of the opening (12) for the connector in the case are in a vertical positional relationship.

Images