JP2003011829A - Control unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small and inexpensive control unit for a motor-driven power steering device remarkably improved in applicability and mounting performance to comparatively large vehicles with increased motor current. SOLUTION: A driving circuit 32 and a shunt resistance 39 are mounted on a metal board 60. A control circuit 33 and connectors 71-74 or the like are mounted on a base material 70. A structure (an interior is a two-piece structure) is provided attaching the metal board 60 and the base material 70 to a radiating case 50 in a laminated state. A connection between the metal board 60 and the base material 70 is realized by fitting a power terminal 62 and a signal terminal 63 on the metal board 60 composed of separated individual terminals in through-holes 75 and 76 of the base material 70 during assembly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control unit for an electric power steering device in a vehicle.

[0002]

2. Description of the Related Art Generally, an electric power steering apparatus detects a steering torque generated on a steering shaft by a steering wheel operation by a torque sensor, and accordingly an assist motor (hereinafter, simply referred to as a motor) attached to a steering shaft or the like. ), A current is supplied from the vehicle battery to generate steering assist torque. This electric power steering device is difficult to generate a large steering assist torque as compared with a hydraulic type, so that it has been mainly used in light vehicles in the past, but it is easy to control electronically or a hydraulic pump is used. It has various advantages such as no need for oil pipes and oil pipes, and has a simpler structure. In recent years, it has been considered to be applied to small vehicles with a displacement of 1800CC level, and may be applied to even larger vehicles in the future. There is. In addition, for the current control of the assist motor in this electric power steering device, a drive circuit including an H-bridge circuit that is normally composed of four (or four sets) FETs (field effect transistors) is used, and a microcomputer (hereinafter, referred to as A control circuit including a microcomputer) controls the assist motor through this drive circuit.
It is driven by the WM (pulse width modulation) method. Also generally,
In this type of device, a power supply backup capacitor (usually an electrolytic capacitor) and a choke coil are connected to a high-potential power supply line that supplies power from the vehicle battery to the drive circuit, which causes ripple current problems and large currents. The problem of temporary power supply voltage drop due to wiring resistance or the problem of noise is solved. A shunt resistor is connected to, for example, a low-potential power line to detect the motor current. In some cases, a power relay for opening and closing the power supply line or the motor energization line is also provided. Then, the drive circuit, the control circuit, or the large current circuit component such as the power source backup capacitor is
It is provided by being mounted on a circuit board in one unit called a control unit, and this control unit (hereinafter, simply referred to as a unit) is arranged in, for example, a gap invisible to passengers in the passenger compartment. .

By the way, a control unit of a conventional electric power steering apparatus has a structure in which one circuit board is housed in a metal case, and the circuit board has a structure as shown in FIG. 9, for example. Was becoming. That is,
The basic structure is the same as that of a so-called printed circuit board, in which a circuit conductor, a passive element, etc. are formed on a resin substrate having an insulating property by a conductor pattern formed by a printed wiring technique.
The above-mentioned FET, power source backup capacitor, or the like, or components such as an IC chip or a power relay forming the above-mentioned control circuit are mounted. By the way, Figure 9
In the circuit board 1 shown in FIG. 2, reference numeral 2 is a resin-molded FET chip, reference numeral 3 is a power source backup capacitor, and reference numeral 4 is the control circuit described above. It is an IC chip of a microcomputer (hereinafter, referred to as a microcomputer chip). Also, reference numeral 5
What is indicated by is a bus bar (conductive plate) that constitutes a circuit conductor through which a large amount of current flows in a motor energizing line, and what is indicated by reference numeral 6 is a radiator that mainly dissipates heat generated in FET2. Reference numeral 7 is a power relay that opens and closes the energization line of the motor under the control of the microcomputer chip 4.

Since a maximum current of about 35 A flows through the assist motor even in the case of a light vehicle, it is necessary to form the energizing line of the assist motor with the conductor pattern on the circuit board 1 having a limited thickness. It was practically impossible in terms of heat generation and space on the substrate. Therefore, the energizing line and the like are configured by mounting the above-mentioned bus bar 5 having a width and thickness significantly larger than the conductor pattern on the circuit board 1 on the circuit board 1. Further, the amount of heat generated in the FET 2 is very large depending on the operating state, and if left unattended, the temperature rises to about several hundred degrees Celsius in a short time. Therefore, the radiator 6 is made of aluminum or the like having a high thermal conductivity, and is placed at the end of the circuit board 1 in parallel with each FET 2 while being joined to the back surface of the FET 2.

[0005]

The control unit of the conventional electric power steering apparatus described above is particularly large-sized vehicle (the current of the assist motor is, for example, 60 to 8).
However, the following problems have been encountered in terms of applicability to devices (which need to be set to 0A) and mountability. (B) In the conventional configuration, when the motor current increases due to application to a relatively large vehicle, the temperature of the printed circuit board rises due to self-heating, and the thermal stress on the solder joints of self-heating components such as shunt resistors is also increased. Is large, and sufficient resistance cannot be obtained in terms of thermal shock due to self-heating. Further, when a large current is continuously applied, the solder may melt and cause a defective connection of components (for example, the shunt resistor described above). (B) Further, since the H-bridge circuit pattern is long, there is a possibility that the radio noise characteristic will deteriorate due to the increase in current and exceed the allowable range. (C) Further, since the components are arranged two-dimensionally on one printed circuit board, the size of the circuit board in the plane direction becomes large and the weight becomes heavy. In particular, in the case of a relatively large vehicle such as a small car, the current of the assist motor is, for example, 80 A at maximum, so that the radiator and the above-mentioned bus bar become extremely large, and the size and weight of the entire unit are directly maintained. As a result, the entire unit becomes extremely large and heavy. In the case of a small automobile, the problem of voltage drop due to wiring resistance between the unit and the motor cannot be ignored due to the increase in the current of the assist motor, and the control unit is practically used in a situation where the wiring cannot be made thick in terms of cost. Must be placed near the assist motor (that is, in the engine room), but as described above, when the unit becomes large, it becomes extremely difficult to place it in the gap in the engine room, and it is difficult to install the device in small vehicles. The application itself becomes difficult in terms of cost and space.

The control unit shown in FIG. 8 is proposed by the applicant in order to cope with the above-mentioned large current. In this unit 10, a metal substrate 12 is attached to the lower surface of a base substrate 11, then this intermediate assembly is assembled to a resin case 13 to which a heat sink 15 (heat sink) is previously attached, and then an insulating substrate 14 (printed circuit board). After mounting on the upper surface of the base substrate 11,
The cover member 16 is attached to the resin case 13 so as to cover the upper surfaces of the base substrate 11 and the insulating substrate 14. The base substrate 11 is a metal substrate 12 or an insulating substrate 14.
Is a support member that is mounted in a stacked manner, and is also a circuit board for mounting the circuit component (large current component) through which a large current flows, such as the power backup capacitor and the power relay described above. The base substrate 11 is formed by integrating a circuit conductor constituting member including a plurality of metal fittings with a resin base material by insert molding.

The metal substrate 12 is an aluminum substrate on which an H bridge circuit including an FET and a shunt resistor are mounted.
It is attached to the lower surface side of the base substrate 11 by adhesion or the like,
The circuit connection with the base substrate 11 is realized by wire bonding. The back surface (lower surface) of the metal substrate 12 is a heat sink 1.
The heat generated in the H-bridge circuit or the like is efficiently radiated. The resin case 13 has a frame-like shape as a whole that can accommodate the base substrate 11 and the like, is a member that constitutes the outer wall of the side surface of the unit 10, and is also a connector 17, 1 for external wiring.
8 and 19 are members integrally provided. Insulating substrate 1
Reference numeral 4 (printed circuit board) mounts a small current component such as a microcomputer chip. The circuit connection between the insulating substrate 14 and the base substrate 11 or the resin case 13 is performed by the lead terminal 2 provided on the base substrate 11 or the resin case 13.
It is realized by press-fitting 0, 21 (press-fit terminals) into the through holes 22, 23 of the insulating substrate 14 during assembly.

With the structure of the control unit shown in FIG. 8, since each circuit component is mounted on the optimal substrate for each function and each substrate is stacked around the base substrate 11, the current is increased. The problem of thermal shock can be solved, the unit can be downsized, and the mountability on the vehicle is improved. However, even with this configuration, the base substrate 1
Since the pattern shape of the power pattern (conductor pattern forming the power supply line and the energization line of the motor) in 1 is complicated and long, the problem of deterioration of radio noise characteristics remains. Further, since the inside of the unit has a three-piece structure in which three substrates are stacked and arranged, a new problem arises that a considerable increase in cost cannot be avoided due to an increase in the number of assembling steps and the number of parts. Therefore, the present invention solves the above-mentioned problems, and particularly, the applicability to a relatively large vehicle in which the motor current increases and the mountability thereof are remarkably improved, and the electric power having excellent radio noise characteristics and cost is also provided. It is intended to provide a control unit for a steering device.

[0009]

A control unit of an electric power steering apparatus according to the present invention is a control unit of an electric power steering apparatus for generating a steering assist torque by an assist motor connected to a steering system of a vehicle. A drive circuit including a switching element that connects each coil terminal of the assist motor to a high-potential power line or a low-potential power line in a switchable manner,
A control circuit that controls the operation of the assist motor by controlling the operation of the switching element of the drive circuit, a base material made of metal, a metal substrate on which the drive circuit is mounted, and a base material made of an insulating material. In addition, the control circuit is mounted, an insulating substrate on which a connector for external connection is mounted, and a heat dissipation case made of metal that forms an outer wall of the unit are provided, and the metal board and the insulating substrate are the heat dissipation case. The signal connection, which is mounted so as to overlap with each other, is connected to the signal line and the power line between the metal substrate and the insulating substrate, and is connected to each other when the substrates are relatively mounted. Part and the power connection part, respectively.

Here, the "driving circuit" mounted on the metal substrate may be a circuit including a bridge circuit for PWM driving the assist motor. Further, the "switching element" includes an FET that constitutes a bridge circuit when the assist motor is PWM-driven. Further, the "control circuit" mounted on the insulating substrate is a circuit including, for example, a microcomputer and its peripheral circuits (peripheral circuits in which a large current does not flow). In addition, large current components such as power supply backup capacitors (usually electrolytic capacitors), noise countermeasure choke coils, power relays that open and close motor energization lines, and shunt resistors for current detection are insulated or metal substrates. It may be mounted on any of the above. However, in consideration of heat dissipation, of these large current components, the component (e.g., shunt resistor) in which heat generation is a particular problem should be mounted on a metal substrate. The "power line" means a power supply line through which a large current flows and a motor energization line.

According to the present invention, since the internal structure of the unit is a two-piece structure in which two substrates (a metal substrate and an insulating substrate) are stacked and arranged, the number of assembling steps and the number of parts are reduced, and the productivity is improved. The cost increase is avoided.
Moreover, each circuit component is mounted on the optimal board for each function,
The substrates are stacked and arranged. Therefore, the unit can be significantly downsized, and the mountability on the vehicle is significantly improved. That is, first, a drive circuit including a switching element that switches the energization state of the assist motor and generating a large amount of heat is
High heat dissipation is ensured by mounting on a metal substrate with good thermal conductivity. As a result, the width and spacing of the conductor patterns on the metal substrate forming the circuit conductor of the drive circuit can be set narrower than in the conventional case, and the area of the drive circuit mounting portion, and thus the area of the entire metal substrate, can be reduced. In addition, the control circuit, in which a small amount of current flows, is mounted on an ordinary insulating substrate and can be arranged within the minimum necessary area. Therefore, it is possible to avoid the interference between the mounted components on the metal substrate and the mounted components on the insulating substrate, reduce the distance between the two substrates, and reduce the space for arranging each substrate and its mounted components in the thickness direction. Becomes Moreover, by stacking the metal substrate and the insulating substrate,
The size in the plane direction is greatly reduced as a whole. Therefore, the size of the unit in the plane direction is significantly reduced, and the size of the unit in the thickness direction can be made approximately the same as the conventional size, and the weight can be reduced accordingly.
Therefore, even in a relatively large vehicle in which the current amount of the assist motor is large, the unit can be highly applicable and easily mounted.

A more preferable structure of the present invention is one in which the back surface of the metal substrate is joined to the inner surface of the heat dissipation case forming the outer wall of the unit. With such a configuration, it is possible to ensure high heat dissipation of the heat generated in the metal substrate while avoiding an increase in the number of parts. This is because the heat dissipation case, which is a heat dissipation member, constitutes the outer wall, so that the member (cover member) that constitutes the outer wall of the portion where the heat dissipation member is provided becomes unnecessary, and the heat dissipation member joined to the metal substrate Since the outer surface is exposed to the outside air,
High heat dissipation is obtained.

Further, according to a more preferable configuration of the present invention, the signal connection portion and / or the power connection portion is a concave terminal (for example, a through hole) provided on the insulating substrate.
And a convex terminal provided on the metal substrate and fitted in the concave terminal, wherein the convex terminal is a discrete terminal surface-mounted by cream solder on a predetermined conductor pattern of the metal substrate. Is. Here, "separate terminals"
Means a single terminal constituted by a member separate from the conductor of the board, and does not include the conductor of the board or the electrode of the connector. With such a configuration, the signal connection portion and / or the power connection portion can be easily realized by surface mounting of discrete terminals or formation of through holes,
More productive.

According to a more preferred structure of the present invention, conductor layers forming the conductor pattern are formed at four corners of a predetermined area of the predetermined conductor pattern of the metal substrate to which the seating surfaces of the loose terminals are soldered. A resist pattern which does not exist and which covers the surface of the conductor pattern is formed up to the peripheral edge of the predetermined area, and a step portion corresponding to the thickness of the resist pattern is formed on the peripheral edge of the predetermined area. It has been done. Here, the “resist pattern” means an insulating layer that protects the surface of the substrate. With such a configuration, in the reflow process of the cream solder, the surface tension of the solder acts to direct the loose terminals toward the center of the predetermined region, and the self-positioning of the loose terminals is automatically performed. The function of alignment is realized and the assemblability is further improved. That is,
The convex terminals positioned with high precision can be configured by simply surface-mounting the discrete terminals, and thus the signal connection portion and / or the power connection portion can be formed by a simple process (that is, at low cost). It can be manufactured with high precision.

Further, a more preferable structure of the present invention is such that a hole into which the cream solder is inserted is formed in the seat surface of the loose terminal. With such a configuration,
The edge distance of the solder fillet formed on the seating surface of the loose terminal is increased, and the thermal shock resistance of the connecting portion (the signal connecting portion and / or the power connecting portion) formed by the loose terminal is improved.

[0016] In a further preferred structure of the present invention, the loose terminal is formed by bending a band-shaped material, and is bent substantially at a right angle from a seat surface of the loose terminal toward a tip portion fitted in the concave terminal. A plurality of parts (preferably a total of 5 positions from the first bent part to the fifth bent part) are provided. In addition, when the said bending part is provided in total 5 places from a 1st bending part to a 5th bending part, the magnitude | size of the part from a 2nd bending part to a 3rd bending part changes from a 4th bending part to a 5th bending part. It is preferable that it is larger than the parts up to. With such a configuration, the center of gravity of the loose terminals is lowered, and the self-sustaining stability of the loose terminals is enhanced, so that the mounting work of the loose terminals becomes easier. Further, even if a force is applied from the insulating substrate to the tip end side (fitting portion) of the loose terminal due to thermal deformation, for example, the loose terminal is flexibly deformed, and this force is applied to the bearing surface of the loose terminal (that is, to the metal substrate). It is possible to sufficiently alleviate the transmission to the soldering portion), which can prevent the occurrence of defective connection of the soldering portion due to heat generation (that is, the stress at the time of heat generation can be relaxed and the thermal shock resistance can be improved. ). Because the loose terminals are made of a strip-shaped material, it is possible to give sufficient flexibility to the external force in the plate thickness direction by setting the plate thickness thin. Further, as described above, the structure having a plurality of bent portions can impart considerable flexibility to an external force in the lateral direction orthogonal to the plate thickness direction. In addition, it bends at 5 points and
With the configuration in which the portion from the bent portion to the third bent portion is set to be relatively large, it can be configured to bend more sufficiently with respect to an external force in the lateral direction orthogonal to the plate thickness direction.

Further, in a more preferable structure of the present invention, a plurality of power patterns of the insulating substrate for connecting the power connecting portion and the corresponding terminals of the connector are formed in the thickness direction of the insulating substrate. The conductor layers have a multilayer structure in which they are connected by through holes in the same pattern, and further, they are arranged substantially linearly and in parallel from the power connecting portion to the terminals of the connector. With such a configuration, the power pattern can be made much more compact than in the conventional case where a power pattern having a complicated and long shape is provided by a single conductor layer or bus bar located on the substrate surface side. It is possible to obtain a sufficiently large conductor cross-sectional area. Therefore, it is possible to improve the radio noise characteristic and to cope with a large current in the specifications of the power pattern (in other words, it is possible to suppress heat generation due to the pattern resistance when the current increases).

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First, an example of a circuit configuration of the electric power steering device will be described with reference to FIG. This device controls an assist motor 31 (hereinafter, simply referred to as a motor 31 in some cases) that is connected to a steering system of a vehicle and generates a steering assist torque, and the motor 31 via a drive circuit 32 (H bridge circuit). This control circuit 3 is based on the outputs of the control circuit 33 and the power supply (battery) 34 of the vehicle.
3, a power supply circuit 35 for supplying a predetermined electric power, and a torque sensor 36 for detecting the steering torque of the steering system. In FIG. 6, reference numeral 30 is a control unit (hereinafter, simply referred to as unit 30) of the electric power steering device.

Further, in FIG. 6, reference numeral 37 denotes an ignition switch of the vehicle, which functions as a start switch of the control circuit 33 in this device. The reference numeral 38 indicates a current of the motor 31 (hereinafter,
It is an electrolytic capacitor that backs up the power supply when the motor current (sometimes simply referred to as motor current) increases. Reference numerals 38a and 38b denote electromagnetic relays (to be exact, contacts of the electromagnetic relays), and the coils of these electromagnetic relays (power relays) are driven and controlled by the control circuit 33 via a circuit (not shown). It is composed. The electromagnetic relay 38a is a power supply relay that opens and closes between the energization line L1 (high-potential power supply line) of the unit 30 and the positive electrode of the power supply, and the electromagnetic relay 38b is a motor that opens and closes the energization line L3 between the drive circuit 32 and the motor 31. It is a relay. These electromagnetic relays are maintained in an open state when the device is not in operation to avoid generation of a large current due to, for example, reverse battery connection (connecting a battery of a vehicle with opposite polarity). Also, if a ground fault occurs during operation of the device, the relay is also switched to the open state in order to avoid generation of a large current due to this fault, malfunction of the motor, or regenerative lock. It is configured to shut off the power line. The regenerative lock here is
FE described later that constitutes the drive circuit 32 (H bridge circuit)
Due to a short circuit failure (ON failure) of T, both terminals of the coil of the motor are connected, so-called regenerative braking force is generated in the motor, and the handle connected to the motor becomes difficult to rotate or rotates. It is a phenomenon that makes operation impossible. To solve such a regenerative lock problem with a relay, it is necessary to provide a relay in the energization line between the H bridge circuit and the motor, like the electromagnetic relay 38b.

The reference numeral 39 indicates the drive circuit 3.
2 is a resistor connected to the ground side, and this resistor 39
The voltage corresponding to the voltage drop of is input to the control circuit 33 by the input line 40. Since the voltage value input from the input line 40 is naturally proportional to the motor current, the control circuit 33 can detect the motor current value from this voltage value, and the resistor 39 and the input line 40 are connected to the motor current. Substantially constitutes the current detection means. Reference numeral 41 is a choke coil for suppressing noise generation, which is connected in series to the energization line L1. The reference numeral 42 indicates the drive circuit 3
2 and a shunt resistor 39 are thermistors for detecting the temperature of the heat generating portion. The drive circuit 32, the control circuit 33, the power supply circuit 35, the electrolytic capacitor 38, the electromagnetic relay 38b, the shunt resistor 39, the choke coil 41, the thermistor 42, and the like are unit components provided in the unit 30. In this case, the electromagnetic relay 38a is provided outside the unit 30 (that is, on the vehicle side), but may be provided inside the unit 30.

In this case, the drive circuit 32 has four field effect transistors SW1 to SW4 (hereinafter, referred to as FETS).
W1 to SW4) are connected to the motor 31 in an H-bridge type, and each FETS is a switching element constituting the H-bridge circuit.
W1 to SW4 operate according to the PWM drive signal output from the control circuit 33. By this operation of each FET SW1 to SW4, each coil terminal of the motor 31 is
Energization line L1 with a duty ratio according to the M drive signal
(High potential power supply line) or energization line L2 (low potential power supply line) is intermittently connected. In addition, each FET SW1
-SW4 are, in this case, N-channel enhancement type MOSFETs, and due to their structure diodes D1-D4.
4 (parasitic diode) is built in between drain and source.

The control circuit 13 is composed of a circuit including a microcomputer, and in order to generate a steering assist torque corresponding to the value of the steering torque detected from the detection signal of the torque sensor 36, the motor corresponding to the steering torque is generated. In addition to the control function in a normal state (normal operating state that is not an abnormal state) of controlling the drive circuit 32 by generating a PWM drive signal with a duty ratio that realizes a target value of current (target current value), for example, a ground fault Is detected and failure response control (FETSW1 to SW
A fail-safe function for avoiding burnout of the FET due to overcurrent by executing processing of turning off all 4 or opening the electromagnetic relay 38a or 38b) is also realized. Also,
The control circuit 33 monitors the temperature condition in the unit 30 by reading a signal from the thermistor 42 or the input line 40, and forcibly reduces the motor current below the target current value as necessary, A fail-safe function (overheat prevention function) for preventing overheating in the unit 30 is also realized. The target current value is a motor current value for generating a target steering assist torque according to (eg, proportional to) the steering torque, but this parameter is also taken into consideration in consideration of parameters other than the steering torque (eg, vehicle speed). The target current value may be obtained. For example, even if the steering torque is the same, the target current value is made different depending on the vehicle speed, and the steering assist torque is made slightly different depending on the vehicle speed.

Further, the power supply circuit 35 sets the voltage of the battery 34 (usually 12V to 14V) to a predetermined voltage (for example, 5V).
V) and supplies it to the control circuit 33. The electromagnetic relay 38a may be provided in the energization line L2 between the drive circuit 12 and the negative electrode (that is, the ground) of the power supply 34, and the electromagnetic relay 38b may be provided between the drive circuit 12 and the motor 31. It may be provided in the other energization line L4. Although not shown, the control circuit 3
Each switching element (FET SW1 to SW4) of the drive circuit 12 is provided in or near the CP 3 in the CP of the control circuit 33.
FET consisting of a transistor for driving by the command of U
A drive circuit, a filter circuit that smoothes a signal input from the input line 40 or the like, or an A / D converter (not shown) that digitizes an input signal (analog signal) from the input line 40 or the thermistor 42. Are provided as needed. Further, normally, a vehicle speed detection signal used for setting the PWM drive signal is input to the control circuit 33 from a vehicle speed sensor provided in the vehicle.

Next, an example of the structure of the unit 30 will be described. FIG. 1 is an exploded perspective view of a main part of the unit 30. 2A is a perspective view of the unit 30 (cover removed state), and FIG. 2B is a unit 30.
3 is a perspective view (completed state) of FIG. As shown in FIGS. 1 and 2A, the unit 30 of this embodiment is roughly divided into
A heat dissipation case 50, a metal substrate 60, an insulating substrate 70,
It is composed of a cover 80 (shown in FIG. 2A). Moreover, the assembly procedure is extremely simple as follows. That is, first, as shown in FIG. 1, the metal substrate 60 and the insulating substrate 70 are sequentially attached to the heat dissipation case 50 with screws 91 and 92, and then the cover 80 is attached to the heat dissipation case 50 with screws 93 as shown in FIG. It will be completed.

Each component will be described below. First, the heat dissipation case 50 has a box shape with an open upper surface, is made of, for example, aluminum (including aluminum alloy) die casting, is a support member to which the metal substrate 60 and the insulating substrate 70 are attached in an overlapping manner, and is also a unit of the unit 30. The cover member covers one surface side, and further functions as a heat sink for heat dissipation. As shown in FIG. 1, in the heat dissipation case 50, a bonding surface 51 to which the lower surface (back surface) of the metal substrate 60 is bonded.
Are provided, and screw holes 52 for screwing the screws 91 are formed at the four corners of the joint surface 51. Supporting portions 53 that support the insulating substrate 70 by contacting the four corners of the insulating substrate 70 are formed at the four corners inside the heat dissipation case 50, and the screws 92 are screwed into the upper surface of the supporting portion 53. A screw hole 54 for forming is formed. Further, a cutout portion 55 for arranging connectors 71 to 74, which will be described later, in an exposed state outside the unit is formed at one end of the heat dissipation case 50.

Next, the metal substrate 60 will be described. The metal substrate 60 is the surface of the aluminum plate which is the base material (mounting surface side)
An insulating layer is formed on the substrate, a conductor pattern as a circuit conductor is further formed thereon by a printed wiring technique, and parts such as a switching element forming the drive circuit 32 are mounted on a predetermined portion of the conductor pattern. Is. In addition, in FIG. 1, the upper surface side is the mounting surface of the metal substrate 60. Further, in this case, the circuit elements mounted on the metal substrate 60 are those surrounded by the one-dot chain line in FIG. 6, that is, the switching elements (FET SW1 to SW4).
A shunt resistor 39 and a thermistor 42.
In FIG. 1, reference numeral 61 denotes an FET chip corresponding to the switching elements (FET SW1 to SW4), and in this case, two FET chips are mounted side by side. The shunt resistor 39 and the thermistor 42 are not shown in FIG. 1 to avoid complication. As shown in FIG. 1, power terminals 62 and signal terminals 63 (separate terminals), which correspond to the convex terminals of the present invention, are mounted on the upper surface of the metal substrate 60 in line by surface mounting with cream solder. Has been.

Of these, the power terminal 62 is the metal substrate 60.
A power connection unit that realizes the connection of the four power lines (the power supply lines L1 and L2 and the energization lines L3 and L4 described above) between the insulating substrate 70 and the insulating substrate 70. This power terminal 62 is shown in FIG. 3 (FIG. 3A is a side view, FIG.
(B) is a bottom view, FIG. 3 (c) is a front view, and FIG. 3 (d) is a perspective view), as shown in FIG. As shown in FIGS. 3 (a) and 3 (d), there are a total of 5 bent portions that bend from the seat surface 62a toward the tip portion 62b at a substantially right angle from the first bent portion K1 to the fifth bent portion K5.
The second bending portion K2 to the third bending portion K are provided at some places.
The length L1 of the portion up to 3 is longer than the length L2 of the portion from the fourth bent portion to the fifth bent portion, and the position of the center of gravity is a low position as indicated by reference numeral G1 in FIG. Is set to. Further, as shown in FIGS. 3B and 3D, a circular hole 62c (through hole) into which the cream solder for surface mounting is inserted is formed in the bearing surface 62a of the power terminal 62.

The signal terminal 63 is connected to a plurality of signal lines (each FET SW1) between the metal substrate 60 and the insulating substrate 70.
~ SW4 drive line, the above-mentioned current detection signal input line 40, the temperature signal input line from the thermistor 42, etc.) is configured to realize a signal connection portion. This signal terminal 63 is also shown in FIG. 4 (FIG. 4A is a side view,
4 (b) is a bottom view, FIG. 4 (c) is a front view, and FIG. 4 (d).
Is a perspective view), and is made by bending a metal strip. Then, as shown in FIGS. 4 (a) and 4 (d), there are a total of three bending portions bent from the seat surface 63a toward the tip portion 63b at substantially right angles from the first bending portion K6 to the third bending portion K8. The position of the center of gravity G2 is also provided in FIG.
As shown in (a), the structure has a low center of gravity set at a low position. In addition, the bearing surface of the signal terminal 63 is also shown in FIG.
As shown in (b) and (d), a circular hole 63c (through hole) into which the cream solder for surface mounting enters is formed. When the power terminals 62 and the signal terminals 63 have such a low center of gravity structure, it is possible to obtain self-sustaining stability in which these terminals are stably maintained in a proper posture in which they are erected straight.

Then, in the metal substrate 60, the portion of the power connection portion on which the convex terminal (power terminal 62) is surface-mounted is configured as shown in FIGS. 5 (a) and 5 (b), for example. There is. That is, in the predetermined conductor pattern 64 to which the power terminal 62 is connected by cream solder,
At the four corners of the quadrangular predetermined area 65 to which the seat surface 62a of the power terminal 62 is soldered, there are provided pattern cut-out portions 66 in which the conductor layer forming the conductor pattern 64 does not exist, and the surface of the conductor pattern 64. A resist pattern 67 (shown in FIG. 5B) covering the above is formed up to the peripheral edge of the predetermined region 65, and a step portion corresponding to the thickness of the resist pattern 67 is formed on the peripheral edge of the predetermined region 65. The predetermined area 65 is the seat surface 62a of the power terminal 62.
The shape corresponds to the shape of the above, and is slightly larger than the seat surface 62a. With this configuration, in the reflow process of the cream solder, the surface tension of the solder directs the power terminals 62 (separate terminals) toward the center of the predetermined region 65, as shown by the arrow in FIG. 5B. The present inventors have confirmed by experiments that the self-alignment function of automatically positioning the power terminal 62 at an appropriate position is realized by the above-mentioned action.

Next, the insulating substrate 70 will be described. The insulating substrate 70 is, for example, a circuit board (for example, a microcomputer chip or a transistor that constitutes its input / output circuit) that constitutes the control circuit 33 by forming a predetermined conductor pattern on a substrate made of synthetic resin by a printed wiring technique, Other circuit elements not mounted on the metal substrate 60 (for example, the power supply circuit 35, the electrolytic capacitor 38, the electromagnetic relay 38b shown in FIG. 6,
And choke coil 41), and further connectors 71, 72, 73, 74 (shown in FIGS. 1 and 2) for external wiring are mounted, and basically the same configuration as a general printed circuit board. Is. Connectors 71, 72, 73,
74, the connector member, which is a component different from the board, is the insulating board 70.
It is screwed to one edge of the. Where the connector 71
Is a connector to which the wiring of the energization line connected to each coil terminal of the motor 31 is connected, and the connector 72 is
A connector to which a power supply wiring connected to the positive electrode or the ground of the battery 34 is connected.
Is a connector to which various signal lines (signal lines of input / output signals with respect to the outside of the unit of the control circuit 33) such as the ignition switch (start switch 37) and the torque sensor 36 are connected. The arrangement direction of these connectors 71 to 74 is parallel to the arrangement direction of the convex terminals (power terminal 62 and signal terminal 63) of the metal substrate 60 described above in the assembled state.

In this insulating substrate 70, the convex terminals (power terminal 62 and signal terminal 63) of the metal substrate 60 described above are used.
As shown in FIG. 1, through holes 75 and 76 corresponding to concave terminals with which the convex terminals are fitted are provided at positions opposite to.
Are formed side by side in a row, and as shown in FIG. 1, the tip ends 62b and 63b of the convex terminals are moved by parallel movement when the insulating substrate 70 is attached to the heat dissipation case 50 (the one to which the metal substrate 60 is attached). Are configured to fit together in these concave terminals. That is, the inserting operation of the convex terminal into the concave terminal is a normal operation when the insulating substrate 70 is attached (in FIG. 1, the insulating substrate 70 is positioned and kept horizontal and lowered to the heat dissipation case 50 or the like). This can all be achieved by the pressing operation).
The installation of 0 (excluding the screwing operation of the screw 92) and the terminal joining for electrical connection are completed. The convex terminals (power terminal 62 and signal terminal 63) and these concave terminals (through holes 75, 76) form the power connection portion and the signal connection portion of the present invention, respectively. Here, the through holes 76 are provided in the number (seven in this case) corresponding to the signal terminals 63, and the tip end portions 63b of the respective signal terminals 63 have a shape dimension that can be easily inserted at the time of the attachment.
Further, the through holes 75 are provided in the number (that is, four) corresponding to the power terminals 62, and the tip portions 62b of the respective power terminals 62 have such a shape dimension that they can be easily inserted at the time of the attachment.

Further, an enlarged view of the insulating substrate 70 shown in FIG.
Of the four through holes 75, the through holes 75a forming the energization line L4 of the motor 31 (see FIG. 6) are shown in FIG.
Is arranged at the most side edge portion (the lowermost portion in FIG. 5C) of the insulating substrate 70, and the energization line L3 of the motor 31 (see FIG. 6).
The through hole 75b constituting the reference hole) is formed adjacent to the inside of the through hole 75a. The through hole 75c forming the low potential power line L2 (see FIG. 6) is formed adjacent to the inside of the through hole 75b, and the through hole 75d forming the high potential power line L1 (see FIG. 6) is formed. , Is formed adjacent to the inside of the through hole 75c. In addition, as shown in FIG. 5C, an edge portion of the insulating substrate 70 where the connectors 71 and 72 are provided is shown in FIG.
, The through holes 71a, 71b, 72c, to which the terminals of these connectors 71, 72 are respectively connected,
72d is the above-mentioned through hole 75 (75a to 75d)
It is formed by being arranged side by side in a line in parallel with. Here, the through hole 71a is connected to a terminal (a terminal connected to one terminal of the motor 31) corresponding to the energization line L4 of the connector 71, and the through hole 71a.
b is connected to a terminal (a terminal connected to the other terminal of the motor 31) corresponding to the energization line L3 of the connector 71. The through hole 72c is connected to a terminal (terminal connected to the ground) corresponding to the power supply line L2 of the connector 72, and the through hole 72d is a terminal corresponding to the power supply line L1 of the connector 72 (power supply). It is connected to a terminal connected to the positive electrode of the power source 34) via the relay 38a.

Then, in the insulating substrate 70, the concave terminals (through holes 75a to 75a) constituting the power connecting portion are formed.
(d) and the corresponding terminals (through holes 71a, 71b, 72c, 72d) of the connectors 71 and 72, the conductor pattern (ie, power pattern) of the insulating substrate 70 is the thickness of the insulating substrate 70. It has a multi-layer structure in which a plurality of conductor layers formed in the same direction are connected by through holes in the same pattern, and further, the concave terminals and the terminals of the connector are arranged substantially linearly and in parallel. That is, as shown in FIG.
5a and the through hole 71a are electrically connected by a power strip P1 which is provided in the insulating substrate 70 and has a horizontally long strip shape as a whole, and the through hole 75b and the through hole 71b.
Are electrically connected by power patterns P2 and P3 that are horizontally long and are provided as a whole adjacent to and parallel to the power pattern P1. Further, the through hole 75c and the through hole 72c are provided adjacent to and in parallel with the power patterns P2 and P3, and the power pattern P4 has a horizontally long strip shape as a whole.
The through hole 75d and the through hole 72d are provided in parallel with each other adjacent to the power pattern P4 and have a horizontally long strip-shaped power pattern P5, P as a whole.
Conducted by 6.

Here, the respective power patterns P1 to P6 are
The four conductor layers formed in the thickness direction of the insulating substrate 70 have the same pattern as a through hole (for example, the through hole 7).
5a to 75d and through holes 71a, 71b, 72c,
72d) has a multi-layer structure. In the case of a general printed circuit board, four conductor layers are formed in the thickness direction, of which the conductor layer on the most front surface side is used alone for a circuit formed on the front surface, and the conductor layer on the most rear surface side is The two inner conductor layers that are used independently for the circuits formed on the back surface are generally used separately for the power supply or the ground. However, in the case of the insulating substrate 70, these four conductor layers have the same pattern shape and are connected by through holes to form the power patterns P1 to P6. In addition, in FIG. 5, the above-described electrolytic capacitor 3 mounted on the insulating substrate 70 is used.
8, the motor relay 38b, the choke coil 41, and the connectors 71 and 72 are indicated by a chain line. Among them, the electrolytic capacitor 38 is connected between the power patterns P4 and P5 (that is, between the high potential power line L1 and the ground). ,
The motor relay 38b is connected between the power patterns P2 and P3 (that is, on the motor energization line L3), and the choke coil 41 is connected between the power patterns P5 and P6 (that is, on the high potential power supply line L1).

The mounting surface of the circuit component of the insulating substrate 70 is, in this case, the inner surface of the unit (lower face in FIG. 1) in the assembled state, and the circuit component on the insulating substrate 70 is mounted on the metal substrate 60. It is arranged on substantially the same plane as the circuit components. Therefore, the metal substrate 60 and the insulating substrate 7
In the end, all the circuit components mounted on any of 0 are accommodated in the minimum necessary space in the thickness direction of the unit 30 (within the same thickness as in the case of a single substrate). Furthermore, in the thickness direction of the entire unit 30 (see FIG.
The size in the vertical direction (in FIG. 2) is the same as the thickness of a large component (eg, electrolytic capacitor 38) mounted on each substrate, and the thickness of the heat dissipation case 50 and the cover 80 are relatively small.
It is about the same as the slight thickness of.

Next, the cover 80 will be described. The cover 80 is made of, for example, press working of a plate material made of steel, and as shown in FIG. 2, a cover main body portion 81 that covers the opening side of the heat dissipation case 50 (the back surface side of the insulating substrate 70) is attached to the vehicle body. The fixing leg members 82 and 83 are fixed by spot welding, for example. This cover body 8
The peripheral edge of No. 1 is joined to the peripheral edge on the opening side of the heat dissipation case 50 (excluding the arrangement portion of the connectors 71 to 74) in the mounted state, and an adhesive agent is applied to this joint portion as necessary, A so-called adhesive seal is applied.

Next, the production process of the unit 30 until shipment will be described. The unit 30 can be easily manufactured by a relatively simple flow as shown in FIG. 7, for example. That is, an aluminum substrate (a component of the metal substrate 60 not mounted) or a printed circuit board (a component of the insulating substrate 70 not mounted) on which a predetermined conductor pattern or resist pattern is formed is manufactured, and the above-mentioned FET chip 61 or Power terminal 62
Etc., or circuit components such as a microcomputer chip are surface-mounted. In the case of the metal substrate 60, the surface mounting here is performed as follows, for example. First, a solder printing step of applying cream solder to a predetermined area of the aluminum substrate is performed using a mold (mask) for applying cream solder. For example, cream solder is applied to the predetermined area 65 (shown in FIG. 5) where the above-described power terminal 62 is mounted, without excess or deficiency. Next, a chip mounting step of positioning and mounting the above-mentioned FET chip 61 and the like on an aluminum substrate by using an automatic machine such as a chip mounter is executed. Then, a terminal automatic mounting step of positioning and mounting the above-mentioned power terminal 62 and signal terminal 63 on an aluminum substrate using an automatic machine is executed. After that, the aluminum substrate is put into a heating tank to temporarily melt the cream solder, and then the reflow process of cooling and hardening the cream solder is executed. In the reflow process, the self-alignment function and the self-sustaining property of the power terminals 62 and the like described above work, so that the power terminals 62 and the like are placed at the proper positions only by performing such a simple and easy surface mounting step. It will be mounted in a proper posture.

Next, for the aluminum substrate (metal substrate 60), as shown in FIG. 7, after the surface mounting process is completed, a characteristic inspection is performed, and then a heat radiating grease printing process is performed. The heat dissipation grease printing process is performed on the back side of the aluminum substrate (heat dissipation case 5
Grease that enhances heat transfer is applied to the joint surface (0). On the other hand, for the printed circuit board (insulating substrate 70), after the surface mounting process is completed, the odd-shaped component that cannot be connected by cream solder is soldered (irregular component soldering), and then the ICT and the substrate coating process are performed. Here, ICT is an in-circuit test. And
The step of sequentially assembling the aluminum substrate (metal substrate 60) and the printed circuit board (insulating substrate 70) completed in this way into the heat dissipation case 50 manufactured by aluminum die casting as described above (aluminum substrate assembly, printed circuit board assembly).
To execute. Next, after performing a necessary soldering after assembling the board, for example, a step of soldering the fitting portions of the power terminals 62 and the signal terminals 63 from the back surface (the upper surface in FIG. 1) of the insulating board 70, adjustment ( For example, soldering correction) and inspection (for example, visual inspection) are executed. afterwards,
The final characteristic inspection is performed after the assembly process of attaching the cover 80 to attach the cover 80, and the product is shipped.

According to the configuration of the unit 30 described above, various practically excellent effects as described below can be obtained. (1) That is, the unit 30 has a two-piece structure in which two substrates (a metal substrate 60 and an insulating substrate 70) are stacked and arranged, so that the number of assembly steps and the number of parts are reduced, and the productivity is improved. It is possible to improve and avoid cost increase (compared to the configuration shown in FIG. 8, the cost can be significantly reduced). Moreover, the respective circuit components are mounted on the optimum substrate for each function, and the respective substrates are stacked. Therefore, the unit can be significantly downsized, and the mountability on the vehicle is significantly improved.

That is, first, the drive circuit 32 and the shunt resistor 39, which generate a large amount of heat, are mounted on the metal substrate 60 having good thermal conductivity to ensure high heat dissipation. As a result, the width and interval of the conductor pattern on the metal substrate 60 forming the circuit conductor of the drive circuit 32 can be set narrower than before.
The area of the drive circuit mounting portion, and thus the area of the entire metal substrate 60, can be reduced. Further, the control circuit 33, which has a small amount of flowing current, is mounted on the insulating substrate 70 which is a normal printed circuit board and can be arranged within the minimum necessary area. Therefore, the interference between the mounted components on the metal substrate 60 and the insulating substrate 70 is avoided, the distance between the two substrates (stacking distance) is reduced, and the space for disposing each of the substrates 60, 70 and the mounted components is reduced. It becomes possible to reduce the thickness in the thickness direction (in this case, the thickness is approximately the same as in the case of a single substrate). Moreover, by stacking the metal substrate 60 and the insulating substrate 70, the size in the plane direction is greatly reduced as a whole. Therefore, the size of the unit in the plane direction is significantly reduced, and the size of the unit in the thickness direction can be made approximately the same as the conventional size, and the weight can be reduced accordingly. Therefore, even for a relatively large vehicle in which the amount of current of the motor 31 is large, high applicability and mountability of the unit can be obtained.

(2) Further, the unit 30 is, in this case, as shown in FIG.
The heat dissipation case 50 is provided so as to form the outer wall on the lower surface side of the metal heat dissipation case 50, and the back surface of the metal substrate 60 is bonded to the inner surface of the heat dissipation case 50. Therefore, it is possible to ensure high heat dissipation of the heat generated in the drive circuit 32 and the like while avoiding an increase in the number of components. This is because the heat dissipating case 50, which is a heat dissipating member, has a structure that constitutes an outer wall, so a member (cover member) that constitutes an outer wall of a portion where the heat dissipating member is provided.
Is unnecessary, and since the outer surface of the heat dissipation member joined to the metal substrate 60 is exposed to the outside air, high heat dissipation is obtained.

(3) Further, in the unit 30, the metal substrate 6
0 and the insulating substrate 70 have a signal connection portion and a power connection portion,
Recessed terminal (through hole 7) provided on the insulating substrate 70.
5, 76) and convex terminals (signal terminals 63, power terminals 62) provided on the metal substrate 60 and fitted in the concave terminals.
The convex terminals are loose terminals that are surface-mounted on the metal substrate 60 with cream solder. Therefore, the signal connection portion and the power connection portion can be easily realized by surface mounting the loose terminals or forming the through holes, and the productivity is further enhanced.

(4) In the unit 30, the metal substrate 5
At the four corners of the predetermined area 65 to which the seat surface of the power terminal 62 (separate terminal) of the conductor pattern 64 of 0 is soldered, the pattern removal portions 66 in which the conductor layers forming the conductor pattern 64 do not exist are provided, and A resist pattern 67 covering the surface of the conductor pattern 64 is formed up to the peripheral edge of the predetermined area 65, and a step portion corresponding to the thickness of the resist pattern 67 is formed on the peripheral edge of the predetermined area 65. Therefore, as described above, in the reflow process of the cream solder, the surface tension of the solder acts to direct the power terminal 62 toward the center of the predetermined region 65, and the power terminal 62 is automatically positioned at the proper position. The self-alignment function is realized, and the assemblability is further improved. That is, by simply surface-mounting the loose terminals that will be the power terminals 62, the power terminals 6 positioned with high accuracy can be obtained.
2 (convex terminal) can be formed, and the power connecting portion between the metal substrate 60 and the insulating substrate 70 can be formed by a simple process (that is,
It can be manufactured with high accuracy (at low cost).

(5) Further, in the unit 30, holes 62c, 63c into which the cream solder is inserted are formed on the bearing surfaces of the power terminals 62 and the signal terminals 63 (loose terminals). For this reason, the distance between the edge surfaces where the fillets of the solder are formed on the bearing surfaces of these loose terminals becomes long, and the connecting portions (the signal connecting portion and the power connecting portion between the metal substrate 60 and the insulating substrate 70) formed by these loose terminals are formed. The thermal shock resistance of is improved.

(6) Further, in the unit 30, the power terminals 62 and the signal terminals 63 (loose terminals) are formed by bending the band-shaped material, and from the seat surface thereof toward the tip end portion fitted into the concave terminal. The power terminal 62 is provided with a plurality of bent portions that bend at substantially right angles, and the bent portions are provided at five locations.
Then, the size of the portion from the second bent portion to the third bent portion is larger than that of the portion from the fourth bent portion to the fifth bent portion. Therefore, the power terminal 62 and the signal terminal 63
Since the center of gravity of the device is low and the self-sustaining stability is improved, the mounting work of these loose terminals becomes easier. Further, even if a force is applied from the insulating substrate 70 to the tip side (fitting portion) of these loose terminals due to, for example, thermal deformation, these loose terminals are flexibly deformed, and this force is applied to the bearing surfaces 62c, 63c (that is, , The soldering part) can be sufficiently mitigated, which can prevent the occurrence of defective connection of the soldering part due to heat generation (that is, the stress at the time of heat generation can be mitigated to improve the thermal shock resistance). it can). Because the power terminal 62 and the signal terminal 63 are made of a strip-shaped material, it is possible to give sufficient flexibility to the external force in the plate thickness direction by setting the plate thickness thin. Further, as described above, the structure having a plurality of bent portions can impart considerable flexibility to an external force in the lateral direction orthogonal to the plate thickness direction. Note that the power terminal 62 described above is particularly used.
Is bent at five points, and the length L1 of the portion from the second bent portion to the third bent portion is set to be relatively large, so that it is more sufficient for the external force in the lateral direction orthogonal to the plate thickness direction. Can be bent.

(7) In the unit 30, the metal substrate 6
0 and the insulating board 70 (through hole 7
5; 75a to 75d) and the corresponding connector 7
1, 72 terminals (through holes 71a, 71b, 72
c, 72d), the power patterns P1 to P6 of the insulating substrate 70 have a multi-layered structure in which a plurality of conductor layers formed in the thickness direction of the insulating substrate 70 are connected by through holes as the same pattern. Further, the power connecting portion and the terminals of the connectors 71 and 72 are arranged substantially linearly and in parallel. For this reason, the power pattern can be remarkably made compact as compared with the conventional case where a power pattern having a complicated and long shape is provided by a single conductor layer or a bus bar located on the substrate surface, and a sufficiently large conductor is used. The cross-sectional area is obtained. Therefore, it is possible to improve the radio noise characteristic and to cope with a large current in the specifications of the power pattern (in other words, it is possible to suppress heat generation due to the pattern resistance when the current increases).

Summarizing the above, the unit 3 of the present embodiment example
0 is compatible with high current, is small and lightweight, has high mountability in a vehicle, has a simple structure, has high productivity, and is relatively inexpensive. Note that the present inventors also perform at least the above-described current limiting (overheating prevention) function based on the detection signal of the thermistor 42, so that even for a relatively large vehicle with a motor current of about 60 A at maximum, The structure of the unit 30 as described above is practicable, and it is superior to the conventional configuration shown in FIG. 9 (or the configuration shown in FIG. 8) in terms of downsizing and the like. Confirmed by tests.

Needless to say, the present invention is not limited to the embodiment described above. For example, the signal terminal 63 in the above-described embodiment may have the same configuration as the power terminal 62 (a configuration having five bent portions). Further, the mounting portion of the signal terminal 63 on the metal substrate 60 may have the same configuration as the mounting portion of the power terminal 62 (the configuration as shown in FIGS. 5A and 5B). In addition, a motor relay such as the electromagnetic relay 38b is not always necessary, and when the above-described regenerative lock does not pose a problem (for example, a clutch is provided between the motor 31 and the steering system to connect the motor 31 and the steering system). It is not necessary if it can be canceled appropriately.

[0049]

According to the present invention, since the internal structure of the unit is a two-piece structure in which two substrates (a metal substrate and an insulating substrate) are stacked and arranged, the number of assembling steps and the number of parts are reduced, and the productivity is improved. And the cost increase is avoided.
Moreover, each circuit component is mounted on the optimal board for each function,
The substrates are stacked and arranged. Therefore, the unit can be significantly downsized, and the mountability on the vehicle is significantly improved. That is, first, a drive circuit including a switching element that switches the energization state of the assist motor and generating a large amount of heat is
High heat dissipation is ensured by mounting on a metal substrate with good thermal conductivity. As a result, the width and spacing of the conductor patterns on the metal substrate forming the circuit conductor of the drive circuit can be set narrower than in the conventional case, and the area of the drive circuit mounting portion, and thus the area of the entire metal substrate, can be reduced. In addition, the control circuit, in which a small amount of current flows, is mounted on an ordinary insulating substrate and can be arranged within the minimum necessary area. Therefore, it is possible to avoid the interference between the mounted components on the metal substrate and the mounted components on the insulating substrate, reduce the distance between the two substrates, and reduce the space for arranging each substrate and its mounted components in the thickness direction. Becomes Moreover, by stacking the metal substrate and the insulating substrate,
The size in the plane direction is greatly reduced as a whole. Therefore, the size of the unit in the plane direction is significantly reduced, and the size of the unit in the thickness direction can be made approximately the same as the conventional size, and the weight can be reduced accordingly.
Therefore, even in a relatively large vehicle in which the current amount of the assist motor is large, the unit can be highly applicable and easily mounted.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a main part of a control unit.

FIG. 2 is a perspective view of a control unit (cover removed state and completed state).

FIG. 3 is a diagram showing a convex terminal (power terminal).

FIG. 4 is a diagram showing a convex terminal (signal terminal).

FIG. 5 is a diagram showing a main part configuration of a metal substrate or an insulating substrate.

FIG. 6 is a diagram showing a circuit configuration of a control unit.

FIG. 7 is a diagram illustrating a production process of a control unit.

FIG. 8 is a diagram showing a comparative example of a control unit.

FIG. 9 is a diagram showing a conventional example of a control unit.

[Explanation of symbols]

30 Control Unit 31 Assist Motor 32 Drive Circuit 33 Control Circuit 50 Heat Dissipation Case 60 Metal Board 62 Power Terminal (Power Connection Section, Convex Terminal, Loose Terminal) 63 Signal Terminal (Signal Connection Section, Convex Terminal, Loose Terminal) 64 Conductor Pattern 65 Predetermined area 66 Pattern removal portion 67 Resist pattern 70 Insulating substrate 71 to 74 Connector 71a, 71b, 72c, 72d Connector terminal 75 (75a to 75d) Through hole (power connection portion, concave terminal) 76 Through hole (signal connection Part, concave terminal) P1 to P6 power pattern

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takeshi Yasuda             Shimogyo-ku, Kyoto-shi Shioji-dori Horikawa Higashiiri Minamifudo-cho             801 OMRON Corporation F-term (reference) 3D033 CA03 CA13 CA16 CA20 CA21                       CA31 CA32

Claims (9)

[Claims] 1. A control unit of an electric power steering apparatus for generating a steering assist torque by an assist motor connected to a steering system of a vehicle, wherein each coil terminal of the assist motor is a high potential power line or a low potential power line. A drive circuit that includes a switching element that is switchably connected to the control circuit; a control circuit that controls the operation of the assist motor by controlling the operation of the switching element of the drive circuit; The mounted metal board, the base material is made of an insulating material, the control circuit is mounted, the insulating board on which the connector for external connection is mounted, and the metal heat dissipation case that forms the outer wall of the unit Wherein the metal substrate and the insulating substrate are attached to the heat dissipation case so as to overlap each other, The connection of the signal line and the power line between the metal substrate and the insulating substrate is realized by a signal connecting portion and a power connecting portion which are provided on each substrate and are joined to each other when the substrates are relatively mounted. A control unit characterized by that. 2. The control unit according to claim 1, wherein a back surface of the metal substrate is joined to an inner surface of the heat dissipation case. 3. The control unit according to claim 1, wherein a shunt resistor for detecting a motor current is mounted on the metal substrate. 4. The signal connecting portion and / or the power connecting portion comprises a concave terminal provided on the insulating substrate, and a convex terminal provided on the metal substrate and fitted in the concave terminal, 4. The control unit according to claim 1, wherein the convex terminals are loose terminals that are surface-mounted by cream solder on a predetermined conductor pattern of the metal substrate. 5. A pattern cutout portion in which a conductor layer forming the conductor pattern does not exist is provided at four corners of a predetermined region of the predetermined conductor pattern of the metal substrate to which the seating surface of the loose terminal is soldered. Further, the resist pattern covering the surface of the conductor pattern is formed up to the peripheral edge of the predetermined area, and a step portion corresponding to the thickness of the resist pattern is formed on the peripheral edge of the predetermined area. The control unit according to claim 4. 6. The control unit according to claim 4, wherein a hole into which the cream solder is inserted is formed on a seating surface of the loose terminal. 7. The loose terminal is formed by bending a band-shaped material, and is provided with a plurality of bent portions that are bent at a substantially right angle from a seat surface of the loose terminal toward a tip portion fitted into the recessed terminal. The control unit according to any one of claims 4 to 6, characterized in that: 8. The bent portion is provided at a total of 5 positions from the first bent portion to the fifth bent portion, and the size of the portion from the second bent portion to the third bent portion is from the fourth bent portion to the fifth bent portion. The control unit according to claim 7, wherein the control unit is larger than the portion up to the five bent portions. 9. The power pattern of the insulating substrate for connecting the power connection portion and the corresponding terminal of the connector is a through hole with a plurality of conductor layers formed in the thickness direction of the insulating substrate as the same pattern. 9. A multilayer structure in which the power connection portion and the terminals of the connector are arranged in a substantially straight line and in parallel with each other. Control unit.