JP2009278727A - Motor controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor controller which effectively reduces generation of noise and effectively eliminates resultant heating. <P>SOLUTION: The motor controller CTL includes: a closed circuit having a direct-current motor M, a current smoothing coil L3, and a diode D6 connected in series; a power MOSFET placed between the closed circuit and a ground line; and a drive unit that on/off-controls the power MOSFET. A first circuit board 11 with the power MOSFET mounted thereon is separated from a second circuit board 10 with a microcomputer MIC including the drive unit mounted thereon. These circuit boards are so constructed that the thermal conductivity of the first circuit board 11 is higher than the thermal conductivity of the second circuit board 10. The two circuit boards are adjacently placed on a single heat sink 12. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a motor control device for an internal combustion engine, and more particularly to a motor control device that can effectively prevent adverse effects caused by heat generation of a switching element that drives a fuel pump.

  In an internal combustion engine such as an automobile engine, fuel in a fuel tank is pumped to a fuel injection valve by a fuel pump and injected into an intake pipe to form an air-fuel mixture. Further, a part of the pumped fuel is returned to the fuel tank via the pressure regulator, so that the fuel pressure is adjusted to a predetermined value. The fuel injection amount is controlled by the opening time of the fuel injection valve.

  The fuel pump is generally composed of a DC motor such as a brush motor or a brushless motor, and the necessary fuel is pumped by controlling the current of the DC motor by a motor control device.

By the way, as a motor control device in such an internal combustion engine, for example, the invention described in Patent Document 1 is known.
JP 2007-231907 A

  In the motor control device described in Patent Document 1, the fuel pressure is measured by a pressure sensor, and the fuel pump discharge pressure is adjusted by controlling the fuel pump drive signal so that the fuel pressure approaches the target pressure. Since such a configuration is adopted, the motor control device of the cited document 1 can perform its own operation without receiving control from an ECU (Engine Control Unit).

  In the above configuration, as a general rule, since it is a one-sided control that depends only on the pressure sensor not involving the ECU, optimal control cannot always be realized. That is, it is considered preferable to realize optimal motor control based on a command signal from the ECU that comprehensively controls the operation of the internal combustion engine.

  Further, in the above invention, since no arbitrary configuration is adopted for the countermeasure against heat generation of the control board, the heat generated by the switching element that drives the fuel pump directly reaches the CPU circuit, which causes the thermal runaway of the CPU circuit. There is a fear.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a motor control device that can effectively prevent adverse effects caused by heat generation of a switching element that drives a fuel pump.

  In order to solve the above problems, the present invention provides a closed circuit including a series connection of a direct current motor, a current smoothing coil, and a diode, and a switching element disposed between the closed circuit and a ground line. A motor control device having a drive unit for ON / OFF control of the switching element, the first circuit board having the switching element mounted thereon, and the second circuit board having the semiconductor element constituting the drive unit mounted thereon , And the first circuit board is configured such that the thermal conductivity of the first circuit board is higher than the thermal conductivity of the second circuit board, while the two circuit boards are placed adjacent to each other on a single heat dissipation member. ing.

  According to the present invention, since the first circuit board on which the switching element is mounted is a separate board from the second circuit board on which the other semiconductor elements are mounted, the heat generated by the switching element directly reaches other semiconductor elements. There is nothing. Therefore, for example, even if the linear operation time of the switching element is prolonged, it is possible to prevent thermal runaway of the semiconductor element due to heat generated in the switching element.

  The adverse effect of heat generation of the first circuit board is eliminated by improving the thermal conductivity of the first circuit board and the configuration of the heat dissipation member. In addition, since the first and second circuit boards are arranged adjacent to each other, there is no possibility that the mutual wiring route is prolonged.

  Hereinafter, the present invention will be described in more detail based on examples. FIG. 1 is a block diagram illustrating an overall configuration of a fuel supply device EQU including a motor control device CTL of an embodiment.

  The illustrated fuel supply unit EQU includes a fuel pump FP that sucks fuel stored in the fuel tank TN, a filter Fi that passes fuel pumped from the fuel pump FP, and fuel that is pumped via the filter Fi. A receiving delivery pipe DP, a pressure regulator PR that adjusts the fuel pressure by returning the fuel to the fuel tank TN when the fuel pressure of the delivery pipe DP exceeds a predetermined value, and a motor control device CTL that controls the operation of the fuel pump FP; The engine control device ECU (hereinafter abbreviated as ECU) for controlling the operation of the motor control device CTL and a battery BT of about DC12V are configured.

  The internal combustion engine of the embodiment is a gasoline engine, and a fuel injection valve EJ that receives fuel from a delivery pipe DP is disposed in a cylinder head of a cylinder block having a plurality of cylinders. The fuel injection valve EJ is configured to inject fuel into the intake port to form an air-fuel mixture, and the air-fuel mixture is ignited by an ignition plug PG disposed in the cylinder head. The operations of the fuel injection valve EJ and the spark plug PG are controlled by the ECU.

  The fuel pump FP of the embodiment is configured by a brush motor M. Then, when the duty ratio of the drive pulse DV supplied from the motor control device CTL is appropriately changed, the average current of the brush motor M is changed to control the pumping amount of the fuel.

  The duty ratio of drive pulse DV is determined based on command signal SG transmitted from ECU to motor control device CTL. The command signal SG is a 1-bit signal in this embodiment, and a control table TBL provided in the motor control device CTL is referred to based on the pulse width of the command signal SG. The control table TBL of the motor control device CTL uniquely defines the relationship between the pulse width of the command signal SG received from the ECU and the duty ratio of the drive pulse DV to be output to the brush motor M.

  In this embodiment, since the duty ratio of the drive pulse DV is determined based on the control table TBL, the relationship between the pulse width of the command signal SG and the duty ratio of the drive pulse DV can be set optimally. That is, even if the change width of the pulse width of the command signal SG is the same, the change width of the duty ratio of the drive pulse DV can be finely changed as necessary. Further, the ECU grasps the operating state of the internal combustion engine based on signals from sensors arranged in each part of the internal combustion engine, and outputs a command signal SG so as to obtain an optimal fuel pumping amount, thereby realizing optimal control. can do.

  As illustrated, the motor control device CTL is configured to output an abnormality signal ER to the ECU. The abnormality signal ER is output when an abnormality is detected in the switching element that outputs the drive pulse DV or when a voltage abnormality of the battery BT is detected. In this embodiment, a power MOSFET is used as a switching element. Specifically, a voltage abnormality between the drain and source of the MOSFET, an excessive drain current, and a battery voltage abnormality are detected.

  When any abnormality is detected, an abnormality signal ER is output from the pump control circuit CTL to the ECU. The detected abnormality content includes the pulse width of the abnormality signal ER and the serial binary signal based on the abnormality signal ER. It is specified by data.

  As described above, the ECU and the pump control circuit CTL communicate in one direction with the command signal SG and the abnormality signal ER each having a 1-bit length. Therefore, when an accurate pulse width cannot be maintained due to noise or the like, malfunction of the pump control circuit CTL or erroneous recognition of the ECU occurs, so that a circuit configuration with particularly excellent noise resistance is required.

  FIG. 2 is a circuit diagram of the pump control circuit CTL configured based on the above request. The illustrated pump control circuit CTL includes a one-chip microcomputer MIC (hereinafter abbreviated as a microcomputer) having a plurality of analog input terminals ANi and digital input / output terminals INi and OUTi, and a power MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). And a motor drive unit MOT driven by an ON / OFF operation. Hereinafter, the power MOSFET may be simply referred to as FET.

  As described above, since the fuel pump FP is configured by the brush motor M, the motor driving unit SW only needs to have a very simple circuit configuration including a single switching element FET. That is, in the brush motor M, the rotor is rotated by sliding the commutator and the brush, so that switching control for changing the direction of the coil current according to the rotation angle of the rotor is not required as in the case of the brassless motor. It becomes. Further, the energy conversion efficiency can be improved as compared with the brushless motor.

The overall configuration of the circuit diagram of FIG. 2 is outlined. The illustrated pump control circuit CTL includes a power supply unit 1 that steps down a battery voltage BT of about 12 V to generate a power supply voltage Vcc (for example, 5 V) of the control circuit, A signal input unit 2 that transmits a command signal SG received from the ECU to the digital input terminal IN1 of the microcomputer MIC, a buffer circuit 3 that receives the drive pulse DV output from the digital output terminal OUT1 of the microcomputer MIC, and a drain-source voltage of the FET A voltage monitoring unit 4 that monitors V _D , a current monitoring unit 5 that monitors the drain current _{ID of the} FET, a signal output unit 6 that transmits an abnormal signal ER output to the digital output terminal OUT2 of the microcomputer MIC to the ECU, A motor drive unit MOT controlled by the ON / OFF operation of the FET and a microcomputer MIC It has been.

<Power supply unit 1>
The power supply unit 1 includes a noise prevention filter in which a coil L1 and two electrolytic capacitors C1 and C2 are connected in a π-type, and cancels noise superimposed on the supply line of the battery voltage BT, thereby reducing the DC voltage. B1 is generated. The electrolytic capacitor C2 has a larger capacity than the electrolytic capacitor C1.

  On the other hand, since the direct current level of the battery voltage BT varies according to the operating state of the internal combustion engine, after the direct current variation is absorbed in the current limiting resistor R1 and the Zener die auto ZD1, a stabilized power source such as a three-terminal regulator is provided. The voltage is stepped down by the circuit RG to generate a power supply voltage Vcc of DC5V. The stabilizing power supply circuit RG is connected to a protective diode D1 and capacitors C3 and C4 for voltage stabilization.

  The DC voltage B1 is divided by the voltage dividing resistors R2 and R3, and then supplied to the analog input terminal AN1 of the microcomputer MIC via a low-pass filter circuit including a capacitor C6 and a resistor R7. The analog input terminal AN1 is connected to an A / D converter built in the microcomputer. In the microcomputer MIC, the level of the DC voltage B1 is abnormal by operating the A / D converter periodically (for example, every several milliseconds). Is to be detected.

  Therefore, when the voltage level of the DC voltage B1 rises abnormally for some reason, the microcomputer MIC immediately detects the abnormality and outputs an abnormality signal ER to the ECU. Further, a fail safe operation for avoiding an abnormal operation of the fuel pump FP can be executed. For example, the duty ratio calculated from the control table TBL is corrected downward to lower the average current of the brush motor M.

<Signal input unit 2>
The signal input unit 2 includes a switching element Q1 that receives a command signal SG from the ECU, voltage dividing resistors R8 and R9 that convert the output voltage of the switching element Q1, a comparator by an OP amplifier AP1 that operates with a single power source Vcc, A low-pass filter that receives the TTL level command signal SG output from the OP amplifier AP1. The low-pass filter includes a resistor R14 and a capacitor C8, and the voltage across the capacitor C8 is supplied to the digital input terminal IN1 of the microcomputer MIC through the resistor R14.

  Since the output part of the OP amplifier AP1 of the embodiment is an open collector, the output terminal of the OP amplifier is connected to the power supply line Vcc through the pull-up resistor R13. A power supply capacitor C7 is connected to the power supply line Vcc.

  As shown in the drawing, the command signal SG whose level is converted by the DC voltage B1 and the voltage dividing resistors R8 and R9 is supplied to the inverting input terminal (−) of the OP amplifier AP1. Protection diodes D2 and D3 are connected to the inverting input terminal (−), and the diodes D2 and D3 are connected to the power supply line and the ground line.

  On the other hand, voltage dividing resistors R10 and R11 are connected to the non-inverting input terminal (+) of the OP amplifier AP1 in order to generate a reference voltage for the comparator. Further, the hysteresis characteristic of the comparator is realized by connecting a feedback resistor R12 between the output terminal of the OP amplifier AP1 and the non-inverting input terminal (+).

  Hereinafter, this hysteresis characteristic will be schematically described. First, it is assumed that the output of the OP amplifier AP1 (comparator) is at the H level (= VH) because the command signal SG is at the L level. In this case, the voltage of the inverting input terminal (−) is approximately B1 * R8 / (R9 + R8) when the ON resistance of the switching element Q1 is ignored.

  On the other hand, the voltage of the non-inverting input terminal (+) is approximately Vcc * R11 / (R11 + R) when simplified to VH = Vcc. Since VH = Vcc is simplified, R is a parallel combined resistance of R10 and R12.

The voltage at the non-inverting input terminal (+) in this operating state means the reference voltage REF _{H of the} comparator, but the reference voltage REF _H increases from Vcc * R11 / (R11 + R10) by the feedback resistance R12. A noise margin for the command signal SG is secured. That is, even if the voltage level which is essentially B1 * R8 / (R9 + R8) increases due to the superimposed noise, the microcomputer is not used unless the increased voltage level exceeds the reference voltage REF _H = Vcc * R11 / (R11 + R). The command signal SG transmitted to the MIC is not garbled.

  Next, since the command signal SG is at the H level, it is assumed that the output of the OP amplifier AP1 (comparator) is at the L level (= VL). In this case, the voltage at the inverting input terminal (−) is approximately B1, assuming that the OFF resistance of the switching element Q1≈∞. On the other hand, the voltage at the non-inverting input terminal (+) is approximately Vcc * R′1 / (R10 + R ′) when VL = 0. In addition, since it is simplified as VL = 0, R ′ is a parallel combined resistance of R11 and R12.

The voltage at the non-inverting input terminal (+) in this operating state means the reference voltage REF _{L of the} comparator, but the reference voltage REF _L is lower than Vcc * R11 / (R11 + R10) by the feedback resistance R12. A noise margin for the command signal SG is ensured. That is, even if the voltage level that is essentially B1 is reduced by the superimposed noise, the voltage level is transmitted to the microcomputer MIC as long as the reduced voltage level does not fall below the reference voltage REF _L = Vcc * R ′ / (R10 + R ′). The command signal SG is not garbled.

  In this embodiment, the 1-bit command signal is transmitted in one direction without returning the confirmation signal of the command signal SG from the ECU to the pump control circuit CTL. As described above, the noise resistance is improved. Since the configuration is adopted, it is possible to prevent the malfunction of the internal combustion engine due to the garbled command signal. Further, by adopting a circuit configuration with improved noise resistance, the entire circuit configuration including the transmission path to the ECU can be simplified and the entire apparatus can be downsized.

<Buffer circuit 3>
The buffer circuit 3 includes a low-pass filter that receives a TTL level driving pulse DV set at a predetermined duty ratio from the digital output terminal OUT1 of the microcomputer MIC, a pair of switching elements Q5 and Q6 whose input terminals are commonly connected, It is composed of a current limiting resistor R23 and protective diodes D4 and D5.

  The two switching elements Q5 and Q6 are not particularly limited, but a C-MOSFET (Complementary MOS FET) is used here for the purpose of suppressing heat generation by suppressing current consumption. That is, a P-channel MOSFET and an N-channel MOSFET are connected in series between the power supply line and the ground line, and the current limiting resistor R23 is connected to the connection point. The two switching elements Q5 and Q6 are complementarily turned on. When the input is at the L level, the upper switching element Q5 (P-MOS FET) is turned on, and when the input is at the H level. The lower switching element Q6 (N-MOS FET) is turned on.

<Motor drive unit MOT>
The motor drive circuit MOT includes a brush motor M that constitutes a fuel pump, a choke coil L3 that smoothes the drive current of the brush motor M, a diode D6 that blocks a reverse current, and a noise blocking coil L2. A switching element that short-circuits a part of a closed circuit constituted by each element to the ground line is mainly configured. A film capacitor C13 is connected between the connection point of the brush motor M and the choke coil L3 and the ground line, and a DC voltage corresponding to the duty ratio of the drive pulse DV is maintained.

  In this embodiment, the switching element is composed of a power MOSFET. The drain terminal of the power MOSFET is connected to the connection point between the coil L3 and the diode D6, and the source terminal is connected to the ground. A protective diode D7 that absorbs reverse voltage is connected between the drain and source terminals. The power MOSFET and the protection diode D7 are integrated to form a single switching element (may be abbreviated as power chip PWR).

The power MOSFET is provided with a current detection terminal SEN so that a sense current I _SEN about 1/500 times the drain current _ID flows out. Although the internal configuration leading to the current detection terminal SEN is appropriate, for example, the sense current I _SEN can be obtained by dividing the source region into a main source part and a sub-source part. Alternatively, a configuration in which a current mirror circuit is formed inside the element to obtain the sense current I _SEN may be used.

  In any case, a capacitor C12 and a resistor R24 are connected in series between the gate terminal and the drain terminal of the power MOSFET to form a delay circuit. This delay circuit is provided to slow down the ON / OFF transition operation in the power MOSFET. In addition, it is the same meaning to provide the low-pass filter by resistance R22 and the capacitor | condenser C11 in the digital output terminal OUT1 of microcomputer MIC.

  As described above, in this embodiment, the transition characteristics in the ON operation and OFF operation of the power MOSFET are intentionally smoothed to prevent the generation of high-frequency noise accompanying the steep ON / OFF transition operation. As a result of the gradual transition operation, the power loss during the transition operation increases and the heat generation of the power MOSFET is promoted, but in this embodiment, a unique heat dissipation configuration is provided to effectively cope with the heat generation of the switching element. (This point will be described later).

  FIG. 3 is a diagram for explaining the operation content of the motor drive unit MOT including a delay circuit including the capacitor C12 and the resistor R24. The brush motor M is repeatedly driven / regenerated by the drive pulse DV output from the microcomputer MIC, and rotates at a speed corresponding to the average current determined by the battery voltage BT and the duty ratio of the drive pulse DV.

  First, consider a transition operation in which the digital output terminal OUT1 of the microcomputer MIC is at the L level and the switching element Q5 is turned on (see FIG. 3A). In this case, the charging route of Q5 → R23 → C12 → R24 functions together with the charging route of the stray capacitance Cf of Q5 → R23 → FET to increase the voltage of the gate terminal of the power MOSFET. However, since the charging route of Q5 → R23 → C12 → R24 is functioning, the voltage increases gradually corresponding to the time constant, and the power MOSFET does not immediately turn on. That is, the power MOSFET performs an ON operation after executing a linear operation (a drain current is proportional to the gate voltage) for a predetermined delay time.

  When the power MOSFET is turned on, a closed circuit of the brush motor M → the coil L3 → the power MOSFET is formed, and a drive current flows through the brush motor M. In the ON state, the power MOSFET has an internal resistance of about 3.8 mΩ, and the capacitor C12 is charged to the maximum level in the direction shown in FIG.

  Next, consider a transition operation in which the digital output terminal OUT1 of the microcomputer MIC transitions to the H level and the switching element Q6 is turned off (see FIG. 3B). In this case, the discharge route of R24.fwdarw.C12.fwdarw.R23.fwdarw.Q6 functions together with the discharge route of the stray capacitance Cf.fwdarw.R23.fwdarw.Q6 of the FET to reduce the voltage at the gate terminal of the power MOSFET. However, since the discharge route of R24.fwdarw.C12.fwdarw.R23.fwdarw.Q6 is functioning, the voltage decreases gradually corresponding to the time constant, and the power MOSFET does not immediately turn off. That is, also in this case, the power MOSFET performs the OFF operation after executing the linear operation for a predetermined delay time.

  In this way, when the power MOSFET is turned off, a closed circuit of the brush motor M → the coil L3 → the diode D6 → the coil L2 is configured, and a regenerative current flows through the brush motor M. Note that the coil L2 is not necessarily arranged in a closed circuit in which a regenerative current flows, and may have a circuit configuration as shown in FIG. 5, for example. In the circuit configuration of FIG. 5, the power supply unit 1 and the motor drive unit MOT are separated, and the drive current of the brush motor M flows through the coil L2. Regardless of which circuit configuration is employed in FIGS. 1 and 5, the coil L2 functions to reduce noise superimposed on the power supply line from the battery BT, and is set to an inductance value that achieves this purpose. Note that the coil L2 may be omitted in the circuit configuration of FIG. 5, and the circuit configuration of FIG. 6 may be employed instead of FIG.

FIG. 3C is a time chart showing the drain current _ID and the drain-source voltage V _D during the ON / OFF transition operation of the power MOSFET. As described above, in the present embodiment, a predetermined linear operation time occurs as a result of the delay operation by the capacitor C12 and the like, and power loss during that time cannot be ignored, but there is no steep rising or falling operation, so there is no high frequency. Noise generation is effectively prevented. Also, ringing, overshoot, undershoot, etc. are avoided.

<Voltage monitoring unit 4>
Next, the voltage monitoring unit 4 will be described. The voltage monitoring unit 4 includes a series circuit of a resistor R25 and a capacitor C14, an inverting amplifier circuit that amplifies the voltage across the capacitor C14, and a low-pass filter circuit that includes a resistor R28 and a capacitor C16. The inverting amplifier circuit includes a single power supply OP amplifier AP2, an input resistor R26, a feedback resistor R27, and a filter capacitor C15.

  A resistor R25 is connected to the drain terminal of the power MOSFET, and the resistor R25 and the capacitor C14 constitute a low-pass filter circuit that eliminates noise. The capacitor C15 also has improved noise resistance.

  As shown in the figure, the output of the low pass filter by the resistor R28 and the capacitor C16 is supplied to the analog input terminal AN2 of the microcomputer MIC. The analog voltage supplied to the analog input terminal AN2 is digitally converted by an AD converter built in the microcomputer MIC.

The voltage V _{D at} the drain terminal of the power MOSFET is substantially zero when the power MOSFET is turned on, but increases to the highest level determined by the duty ratio of the drive pulse DV when the power MOSFET is turned on (FIG. 3C). However, when the power MOSFET deteriorates and the internal resistance during the OFF operation decreases, the voltage V _{D at the} drain terminal does not increase to a predetermined level. When the drain-source is short-circuited, the drain terminal voltage V _D becomes zero.

Therefore, in this embodiment, the analog voltage supplied to the analog input terminal AN2, the microcomputer MIC is by obtaining regularly AD converter monitors the voltage V _D of the drain terminal. When the voltage V _{D at the} drain terminal does not rise to a predetermined level, an abnormal signal ER indicating that fact is output to the ECU. In this embodiment, since the drain terminal voltage V _D is grasped at an analog level, it is possible to appropriately cope with the abnormal level.

<Current monitoring unit 5>
The current monitoring unit 5 includes a parallel circuit of a resistor R29 and a capacitor C17 connected to the current detection terminal SEN of the power MOSFET, an inverting amplifier circuit that receives the voltage across the resistor R29 and the capacitor C17, and a low-pass filter that includes a resistor R32 and a capacitor C19. It consists of and. The inverting amplifier circuit includes a single power supply OP amplifier AP3, an input resistor R30, a filter capacitor C18, and a feedback resistor R31.

  The output of the low-pass filter by the resistor R32 and the capacitor C19 is supplied to the analog input terminal AN3 of the microcomputer MIC. The analog voltage supplied to the analog input terminal AN3 is digitally converted by an AD converter built in the microcomputer MIC.

As shown in the figure, in the current monitoring unit 5, the sense current I _SEN of the power MOSFET flows through the resistor R29, so that a voltage proportional to the sense current I _SEN is supplied to the analog input terminal AN3. Here, since the sense current I _SEN is about 1/500 times as large as the drain current _ID , the microcomputer MIC periodically AD-converts and monitors the analog voltage of the analog input terminal AN3, thereby monitoring the drain current I It is possible to detect an abnormal current flowing through _D excessively.

By the way, conventionally, for the purpose of such current monitoring, a shunt resistor is arranged in the current path of the drain current _ID . In the configuration using the shunt resistor, even if the drain current _ID is 10 A, which is a normal level, for example, to obtain a detection voltage of 1 V, a shunt resistor of 100 mΩ is necessary, and a power loss of 10 W occurs. Therefore, an expensive shunt resistor that can withstand the heat generated by the power loss is necessary. However, in this embodiment, since the sense current I _SEN that is approximately 1/500 times proportional to the drain current _ID is used, even if the detection sensitivity is increased, no adverse effect due to power loss occurs.

<Signal output unit 6>
The signal output unit 6 includes a low-pass filter that receives the abnormal signal ER from the digital output terminal OUT2 of the microcomputer MIC. The low-pass filter includes a resistor R15 and a capacitor C9, and the abnormal signal ER that has passed through the low-pass filter is transmitted to the ECU via, for example, a current amplification circuit.

The abnormal signal is either (a) the battery voltage BT becomes an abnormally high level, (b) the drain voltage V _D when the power MOSFET is OFF, or (c) when the power MOSFET is ON. It occurs when the drain current _ID becomes abnormally high. The abnormality content is specified by the pulse width of the abnormality signal ER.

  Next, the structure of the bump control device CTL will be described. As shown in FIG. 4A, this device CTL closes the resin case 13 and the heat sink 12 in which the two circuit boards 10 and 11 are arranged adjacent to each other, the resin case 13 that houses the circuit elements for the filter operation. And it is comprised with the case cover (not shown) which integrates the whole. In the present embodiment, the circuit of FIG. 2 is realized as a whole by using two circuit boards 10 and 11 instead of a single circuit board. Therefore, the optimum heat dissipation performance of the power chip PWR can be realized without particularly increasing the manufacturing cost. Hereinafter, this point will be specifically described.

<Circuit boards 10, 11>
Specifically, the circuit board 10 is a glass epoxy board on which semiconductor elements such as a microcomputer MIC, an OP amplifier, and a diode, capacitors other than the capacitors C1, C2, and C13, resistors, and the like are mounted.

  On the other hand, the circuit board 11 is an aluminum nitride ceramics board on which a power chip PWR is mounted. More specifically, a copper foil layer is provided on the front and back surfaces of the aluminum nitride ceramic substrate by metallization, the power chip PWR is soldered to the upper copper foil layer, and the lower copper foil layer is attached to the heat sink 12. It is glued. The power chip PWR has five connection terminals (FIG. 2), all of which are wire-connected to corresponding portions of the circuit board 10.

  The circuit board 10 and the circuit board 11 are both bonded to the heat sink 12 by an adhesive, but the adhesive of the aluminum nitride ceramics substrate 11 is selected from a material that has better heat transfer than the adhesive of the glass epoxy substrate 10. . In order to increase the heat transfer property of the adhesive, for example, the heat transfer filler may be contained in the adhesive. However, as the heat transfer filler, a metal having high thermal conductivity such as silver, copper, aluminum, alumina, nitriding, etc. Ceramics with high thermal conductivity such as aluminum, silicon carbide and graphite are employed.

  In addition, the aluminum nitride ceramic substrate 11 has excellent characteristics such as higher heat conduction and thermal emissivity and higher heat dissipation than the glass epoxy substrate 10 and the like. Metallization processing is also possible. Therefore, as in this embodiment, the power chip PWR performs a linear operation for a predetermined time, so that even if the amount of heat generation increases (see FIG. 3C), the heat generation can be effectively radiated. The heat dissipation path is: power chip PWR → copper foil layer → aluminum nitride ceramic substrate 11 → copper foil layer → adhesive → heat sink 12.

  In the present embodiment, since the circuit board 10 and the circuit board 11 are not integrated, the heat generated in the aluminum nitride ceramic substrate 11 is not directly transferred to the glass epoxy board 10, and therefore the microcomputer MIC. There is no possibility of adversely affecting the semiconductor element. In addition, since the adhesive of the glass epoxy board | substrate 10 is somewhat inferior in heat conductivity, the heat radiation path | route to the aluminum nitride ceramics substrate 11-> glass epoxy board | substrate 10 is not considered practically.

  On the other hand, when the entire circuit shown in FIG. 2 is mounted on a single board as in the conventional device, the more the circuit board with better heat transfer is used, the more power is transferred from the power chip PWR to the microcomputer MIC. The harmful effect of promoting heat occurs.

<Heatsink 12>
The heat sink 12 is configured by projecting a plurality of fins Fin from a substantially rectangular plate material. The plurality of fins Fin may extend in the longitudinal direction, but in this embodiment, the fins extend in the short direction (width direction). Comparing the case of providing fins extending in the short direction and the case of providing fins extending in the longitudinal direction, taking into account restrictions in the manufacturing process, the fins are provided in the short direction, thereby reducing the total volume of the heat sink 12 Even if it makes it, it can increase a thermal radiation surface area.

  Therefore, in the circuit configuration of this embodiment in which the heat generated from the power chip PWR tends to increase, the fin configuration extending in the short direction is particularly effective. Further, in this embodiment, the heat radiation area is increased by slightly narrowing the pitch of the fins corresponding to the arrangement position where the circuit boards 10 and 11 are mounted.

<Resin case 13>
The resin case 13 is configured such that a connector portion 13B including the connection terminal 14 is connected to one end of a case body portion 13A formed in a box shape. In this embodiment, the connection terminal 14 includes an input terminal for battery voltage, an input terminal for command signal SG, an output terminal for abnormal signal ER, an output terminal for brush motor M (+), an output terminal for brush motor M (- ) And a total of six ground terminals are arranged (see FIG. 2).

  The bottom surface of the case main body 13A is provided with a locking portion for arranging a circuit element for filter operation, and a passage hole through which the connection terminal 20 (FIG. 4 (d)) extending upward from the circuit boards 10 and 11 passes. Is formed. In consideration of heat dissipation of the circuit boards 10 and 11, an open hole is formed above the circuit boards 10 and 11.

  FIG. 4C is a schematic view showing the resin case 13 in a plan view, and the film capacitor C13, the electrolytic capacitor C1, and the electrolytic capacitor C2 are arranged in a substantially L shape. Further, a choke coil L3 is disposed adjacent to the large electrolytic capacitor C2, and coils L1 and L2 are disposed adjacent to the choke coil L3. The circuit boards 10 and 11 are arranged on the upper surface of the heat sink 12 so as to correspond to the open holes provided on the bottom surface of the case main body 13A.

  Most of the circuit elements housed in the case main body 13A are filter members for exhibiting noise resistance, and generally large elements are required to achieve desired performance. However, in this embodiment, since the transition operation of the power chip PWR is eased to suppress the generation of noise, each filter member can be reduced in size compared with the case of the steep transition operation, and the entire apparatus can be reduced. It can be downsized.

  Further, in this embodiment, the circuit board 11 for the power chip PWR that generates the most heat is composed of an aluminum nitride ceramics substrate with excellent heat dissipation, so that the electrolytic capacitor C2 and the like are close to the power chip PWR. Circuit elements can be arranged, and as a result, the entire apparatus can be downsized in this sense.

  By the way, in this embodiment, the circuit board 10 so that the connection between the circuit elements C1, C2, C13, L1 to L3 accommodated in the case main body 13A and the circuit boards 10 and 11 can be realized by the case main body 13A. , 11, a plurality of connection terminals 20 are extended upward (see FIG. 4D). Therefore, in the present embodiment, the connection work of the connection terminals 20 can be performed in a state where the resin case 13 is covered with the heat sink 12, and the workability is good. Since the resistance welding method is employed for the connection work, the welding work can be completed efficiently in a short time, which contributes to the reduction of manufacturing costs. The resistance welding means a joining method in which a welding current is melted and joined by causing a large current to flow for a short time to generate resistance heat.

  As described above, according to the present embodiment, the motor control device CTL can be extremely miniaturized. Further, heat generated by the power chip PWR due to noise suppression by the delay circuit is effectively radiated by the configuration of the circuit boards 10 and 11 and the heat sink 12. The specific description does not particularly limit the present invention, and various modifications can be made without departing from the spirit of the present invention. In particular, the materials of the circuit boards 10 and 11 and the specific configuration of the heat sink 12 are appropriately changed according to technological progress.

It is a block diagram which shows the whole structure of the fuel supply apparatus which uses the motor control apparatus which concerns on an Example. It is a circuit diagram which shows the circuit structure of the motor control apparatus which concerns on an Example. It is drawing explaining operation | movement of a delay circuit. It is the schematic which shows the apparatus structure of the motor control apparatus which concerns on an Example. It is a circuit diagram which shows the deformation | transformation circuit structure of a motor control apparatus. It is a circuit diagram which shows another modified circuit structure of a motor control apparatus.

Explanation of symbols

M DC motor L3 Current smoothing coil D6 Diode 10 Second circuit board 11 First circuit board MIC Semiconductor element

Claims (7)

A closed circuit including a series connection of a direct current motor, a current smoothing coil, and a diode, a switching element disposed between the closed circuit and a ground line, and a drive unit that controls ON / OFF of the switching element A motor control device comprising:
The first circuit board on which the switching element is mounted and the second circuit board on which the semiconductor element constituting the driving unit is mounted are separate substrates, and the thermal conductivity of the first circuit board is the thermal conductivity of the second circuit board. A motor control device for an internal combustion engine in which the two circuit boards are mounted adjacent to each other on a single heat radiating member while being configured to be higher than the rate.   The motor control device according to claim 1, wherein the first circuit board is made of aluminum nitride ceramics.   The metal layer is formed in the front and back of the 1st circuit board, the said switching element is fixed to the metal layer of the surface side, and the metal layer of the back surface side is adhere | attached on the said heat radiating member. Motor control device.   The motor control device according to claim 1, wherein the first circuit board is made of glass epoxy.   5. The heat transfer rate of the adhesive that bonds the first circuit board to the heat dissipation member is set higher than the heat transfer rate of the adhesive that bonds the second circuit board to the heat dissipation member. The motor control device described in 1. The heat dissipating member is integrally composed of a substantially rectangular plate material and a plurality of fins protruding from the plate material,
The motor control device according to claim 1, wherein the plurality of fins are arranged in a row extending in the width direction.   The motor control device according to claim 6, wherein the heat dissipating surface area is relatively increased by densely setting the arrangement pitch of the plurality of fins corresponding to the arrangement position of the first circuit board.

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