JP2001309690A - Drive device of electric load - Google Patents

Abstract

PROBLEM TO BE SOLVED: To contrive the small size and low cost of a heating element and contrive the small size and low cost of a whole device in the drive device of electric load provided with a plurality of the heating elements. SOLUTION: In an H bridge circuit for motor drive, low side transistors (FET) Tr3, Tr4 are approximated and mounted on a substrate 44, and a copper foil pattern for heat conduction PT is formed on the rear face of the substrate 44. When a motor is driven, any one of the transistors Tr3, Tr4 is always turned off, and the other is driven in duty. Heat generated from the radiation part of the transistor (drain terminal D3 or D4) during operation is conducted and absorbed to the radiation part of the transistor during non-operation through the insulator of the substrate 44 and a copper foil pattern PT well. Thereby since the temperature of the transistor is reduced during operation, the transistor of large on-resistance and small chip size can be used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a driving device for driving an electric load such as a motor, and more particularly to a driving device for an electric load using a plurality of driving elements.

[0002]

2. Description of the Related Art Conventionally, information from various switches and sensors provided in various parts of a vehicle is input to a microcomputer and various calculations are performed based on the information. 2. Description of the Related Art An electronic control device that controls a vehicle by being driven has been widely known.

[0003] In particular, with the recent rapid computerization of vehicle systems, various mechanisms are driven by driving motors, such as opening and closing control of a throttle valve in an internal combustion engine, idle speed control, and shift range switching control of an automatic transmission. The systems that operate are increasing. In a driving device for driving a motor, various driving circuits are configured according to the type of the motor to be used and the control method. For example, six driving elements such as power transistors are provided, and these are driven by PWM.
A so-called H-bridge circuit, which includes a drive circuit that supplies three-phase alternating current to an AC motor by controlling it, and four drive elements, and controls energization of a DC motor by controlling on / off of these drive elements. Alternatively, a drive circuit of a step motor or the like is well known.

In such a motor drive circuit, the rotational direction, rotational position, torque, etc. of the motor are controlled by sequentially energizing (turning on) a plurality of drive elements or adjusting the duty ratio of the energized drive elements. Thus, a controlled object such as a valve opening can be appropriately driven and controlled.

A drive element such as a power transistor easily generates heat when energized. Therefore, when selecting a drive element, the operating conditions (current value, current value,
A component having a power loss within a usable range is appropriately selected in consideration of the energization time, the duty, and the like. Also, a method of improving the heat radiation performance by attaching a radiation fin to the driving element so that the driving element can be used for a driving element having a large power loss (that is, a large amount of heat generation) is generally used.

In recent years, radiation fins that dissipate heat to the above-described device housing have been abolished, and small drive elements that dissipate heat to the substrate, such as surface-mounted components and elements with heat sinks, have been adopted. By selecting the drive element in consideration of the heat radiation performance in the state of being mounted on the device, the size and cost of the entire device can be reduced.

In this case, if a driving element having a smaller on-resistance (in other words, a smaller power loss) is used,
Further, the size of the device can be reduced by reducing the size of the driving element. That is, the smaller the element, the worse the heat radiation performance. Therefore, the on-resistance of the element is reduced to suppress the amount of heat generation, thereby trying to cover the deterioration of the heat radiation performance.

[0008]

However, by using such a driving element having a small on-resistance, it is possible to reduce the size of the driving element. However, in order to reduce the on-resistance, an internal chip (semiconductor) is required. It is necessary to use a drive element having a large chip size, which increases the cost of the drive element. That is, although the size of the entire drive element (package) can be reduced, the internal chip must be increased accordingly, and the reduction in size and cost of the drive element cannot be achieved at the same time.

As a method for solving such a problem, for example, Japanese Patent Application Laid-Open Publication No. 6-507049 discloses that good heat radiation from an output component (heat-generating component) can be achieved by using an apparatus housing or the like. A method for doing so is disclosed. Specifically, heat-generating components provided with cooling fins are formed on the both sides of the outer peripheral portion of the substrate in a ring shape. They are arranged so that they come into contact with each other. Further, a casing (device housing) for accommodating the substrate and the like is also configured to be in thermal contact with the coating on the outer peripheral portion of the substrate, so that a heat-radiating component or the like is not separately added to the heat-generating component. Good heat dissipation is realized.

[0010] However, in the above method, although the heat radiation performance is improved, it is necessary to provide a coating for heat radiation on the outer peripheral portion of the substrate, and the substrate becomes correspondingly large. In addition, since all of the plurality of heat-generating components are arranged annularly on the outer periphery of the substrate, the distance between the heat-generating components and the external input / output terminals (such as connectors) on the substrate becomes longer, and a thick wiring pattern is not formed longer. Will not get.

As a result, although the components can be reduced in size, the size of the substrate is increased and the size of the entire device is increased, resulting in an increase in cost. A control circuit for controlling the operation of the heat-generating component is also provided on the board, but a thick wiring pattern from the heat-generating component disposed on the outer periphery of the board to the connector passes near the control circuit. Therefore, the control circuit may malfunction due to electromagnetic noise radiated around the wiring pattern by a current flowing through the wiring pattern (for example, a current for driving an external load).

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and in a driving apparatus for an electric load having a plurality of heating elements, the heating elements can be reduced in size and cost, and the entire apparatus can be reduced in size and cost. The purpose is to reduce costs.

[0013]

Means for Solving the Problems and Effects of the Invention The driving device according to claim 1 has been made to solve the above problems.
It has a plurality of heating elements provided in a current supply path to one or a plurality of electric loads. Then, among the plurality of heating elements, at least two heating elements that are not continuously energized with each other are mounted close to the substrate, and between the closely mounted heating elements, A heat conducting member is provided.

The drive elements mounted close to each other do not operate continuously (become energized), and a period occurs in which one of the heating elements does not operate (becomes non-energized). Therefore, when one of the heating elements is not operating, the heat generated from the other operating heating element can be absorbed by the non-operating heating element via the heat conducting member. Performance is better,
More current can flow through the drive element. This means that it is possible to use a heating element having a larger power loss (for example, a smaller element size) during energization.

Therefore, according to the first aspect of the present invention, the heat generated by the operating heating element is absorbed by the non-operating heating element when the adjacently mounted heating element is not operating. Therefore, it is possible to reduce the size of the heating element and reduce its cost. This also makes it possible to reduce the size and cost of the entire apparatus.

The heating element may be, for example, an active element such as a power transistor, or a passive element such as a resistor or a solenoid. The heating elements mounted close to each other do not operate continuously. Anything that can absorb heat can be used. In addition, the term “not continuously energized” as used herein does not necessarily mean that one of the heating elements must not be in an energized state during driving of the electric load. The case where the element is always in the energized state and the energization to the other heating element is duty-controlled. That is,
There is a period during which power is not supplied to one of the electric loads while the electric load is being supplied to the electric load. Any period may be used as long as heat generated by the operating heating element can be absorbed by the non-operating heating element.

Here, as the heat conduction member, for example, a wiring pattern formed on a substrate may be used. Here, the wiring pattern refers to a conductive metal formed on the substrate on which the heating element is mounted, such as a well-known copper foil pattern or through hole formed on the substrate for electric conduction. With this configuration, the wiring pattern on the substrate can be effectively used as a heat conducting member without providing a new component only for heat conduction, so that the driving device can be further reduced in size and cost can be reduced. Can be

Further, as described above, the present invention can be applied to any heating element such as a resistor and a power transistor. However, as described in claim 3, the conduction path of the electric load is turned on / off. It is more effective when applied to a switching element. That is, for example, a switching element such as a power transistor conducts and cuts off a current supplied to an electric load, and the amount of the supplied current is also a relatively large current necessary for driving the electric load. A large amount of heat is generated from the switching element when energized. Therefore, by mounting a plurality of switching elements that are not continuously energized close to each other via the heat conductive member, it is possible to reduce the size of the switching element that generates a large amount of heat.

Further, the plurality of heating elements mounted close to the substrate may be mounted so that the substrate is sandwiched between the front and back surfaces of the substrate. With this configuration, it is not necessary to separately provide a heat conduction member, and heat can be conducted at a portion of the substrate between the heating elements mounted on the front and back surfaces. That is, heat can be directly and planarly transmitted through the substrate, and the heat radiation effect is further enhanced, as compared with the case where the substrate is arranged close to the same surface on the substrate. for that reason,
In addition to the downsizing of the heating element, the mounting area on the substrate can be reduced by mounting on the front and back surfaces, so that the entire driving device can be further downsized.

The relative positional relationship between the heating elements mounted on the front and back surfaces is such that, in consideration of good thermal conductivity, the heating elements are mounted on the front and back surfaces at the same position on the board (that is, the heating elements are mounted on the board). It is desirable that they are completely mounted on the front and back surfaces of the board at the same position, but it is not necessary to completely mount them on the board. However, it is sufficient if it is implemented so that it exists.

Here, the invention according to claims 1 to 4 includes, as described in claim 5, four switching elements as heating elements, and an H bridge circuit composed of the four switching elements. The present invention can be applied to a drive device capable of controlling the direction of current supply to one motor as an electric load. And, of the four switching elements,
Two switching elements that are not continuously energized are mounted close to each other.

Normally, when the motor is driven by the H-bridge circuit, the direction of power supply to the motor is controlled by appropriately controlling the on / off of the four switching elements. Therefore, all four switching elements are not turned on at the same time when the motor is driven. Therefore, if two of the four switching elements, which are not continuously energized, are mounted so as to be close to each other, the heat generated by the switching element during operation is reduced by the other of the closely mounted switching elements. It can be absorbed by the switching element.

Therefore, the present invention is applied to an H bridge circuit having a large number (four) of switching elements (claims 1 to 4).
When applying, the four switching elements are reduced in size,
This is more effective because the motor drive device can be reduced in size and cost.

When the motor is driven by the H-bridge circuit, for example, two switching elements connected to one of the positive and negative polarities of the power supply are used to select the direction of conduction (direction selection side). In general, two switching elements connected to the other polarity are used for energization control (energization control side).

That is, for example, one of the two switching elements on the direction selection side is always turned on, and one of the two switching elements on the conduction control side is always turned off. This determines the direction of power supply to the motor.
Then, when the other switching element (direction selection side drive element) on the direction selection side is turned off and the other element (current control side drive element) on the conduction control side is turned on, power is supplied to the motor.

In order to control the amount of current supplied to the motor, for example, duty control may be performed on the energization control side drive element. Due to the generated magnetic energy (arcing energy), the current flowing through the motor does not immediately become zero. Therefore, for example, by turning on the switching element that was turned off on the direction selection side at the same time as turning off the energization control side drive element, the two switching elements on the direction selection side and the motor
A free-wheeling circuit is formed, which can consume the magnetic energy of the motor and reduce the current to zero.

In other words, in this case, the arc-quenching energy when the power supply to the motor is turned off is consumed on the direction selection side, and the two switching elements on the direction selection side both have a period in which current flows at the same time. In the two switching elements on the conduction control side, there is no period in which current flows at the same time.

Therefore, in the driving device for driving the motor by the H-bridge circuit according to the fifth aspect,
As described in, two switching elements connected to either the positive or negative polarity of the power supply of the motor, and in order to control the direction and magnitude of the current when the motor is energized, When one is always off and the other is duty-controlled, it is particularly effective to mount the two switching elements in close proximity.

In this way, one of the two switching elements mounted close to each other is always turned off, and there is no period in which both are energized at the same time. Will be In this case, the effect of the present invention can be obtained even if switching elements having a period during which they are simultaneously turned on are mounted close to each other. Performance will be slightly worse.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. [First Embodiment] FIG. 1 is a schematic configuration diagram showing the configuration of a throttle control system for a vehicle to which the present invention is applied.

As shown in FIG. 1, the throttle control device according to the present embodiment includes a throttle valve 1 for adjusting a flow rate of air flowing through an intake air pipe 7 toward an internal combustion engine 9.
And a motor 2 for rotating the throttle valve 1, which is connected to a rotation shaft of the throttle valve 1, and attached to a throttle body (not shown) for detecting the opening of the throttle valve 1. A throttle opening sensor 3 for outputting a voltage proportional to the throttle opening, a pedal position sensor 4 for detecting an operation amount of the accelerator pedal 8 by the driver and outputting a voltage proportional to the operation amount, and a throttle opening sensor 3 and a signal (output voltage) from the pedal position sensor 4, and in accordance with these input signals, an electronic controller for controlling the energization of the motor 2 in order to control the opening of the throttle valve 1 to a desired opening. A control device 5, a battery 6 mounted on the vehicle to supply power to the motor 2, and an energization path from the battery 6 to the electronic control device 5 Composed of the ignition switch 7 for for passing or blocking. The motor 2 is a well-known DC motor in which the rotation direction is controlled by the energization direction and the rotation torque is controlled by the amount of current.

The electronic control unit 5 is mainly composed of a microcomputer (hereinafter simply referred to as "microcomputer") 11, a motor drive circuit 12, and a current detection circuit 13, the details of which are shown in FIG. Show. The microcomputer 11
It is a well-known device having a CPU, a ROM, a RAM, an I / O, a bus line, and the like. The microcomputer 11 inputs the output voltage from the throttle opening sensor 3 after being divided by the resistors R1 and R2, and the output voltage from the pedal position sensor 4 is divided by the resistors R3 and R4. And the output voltage from the current detection circuit 13 is input after being divided by the resistors R5 and R6. Then, based on these input signals (voltages), a control signal for controlling energization to the motor 2 is output to the drive logic unit 21 in the motor drive circuit 12.

Although not shown, the microcomputer 11 supplies the input voltage, the engine speed, the cooling water temperature,
Various signals such as intake / exhaust temperature and battery voltage are also input, and control of each part of the vehicle (for example, ignition timing control and idle speed control) is performed based on these various input signals. The power for operating the microcomputer 11 is also supplied from the battery 6 via the ignition switch 7.

The motor drive circuit 12 includes four N-channel MOS type FETs (field effect transistors, hereinafter simply referred to as "transistors") Tr1, Tr2, Tr3, T
An H-bridge circuit composed of r4 is provided. Specifically, the drains of the transistors Tr1 and Tr2 (high-side transistors) are connected to the positive electrode side of the battery 6 through an ignition switch 7, and
The sources of r3 and Tr4 (low-side transistors) are connected to a power supply line (ground line) at the same potential as the negative electrode side of the battery 6 via a resistor R11 in the current detection circuit 13. The four transistors Tr1 to Tr1
Tr4 corresponds to a switching element as a heating element of the present invention.

The source of the transistor Tr2 is connected to the drain of the transistor Tr3, and the connection point A is connected to one end of the motor 2, and the transistor Tr2
The source 1 is connected to the drain of the transistor Tr4, and the connection point B is connected to the other end of the motor 2. Although the motor 2 is actually provided near the throttle valve 1 as shown in FIG. 1, in FIG.
Are described together with the motor 2.

In such an H-bridge circuit, when all of the transistors Tr1, Tr2, Tr3 and Tr4 are in the off state, if the high-side transistor Tr1 and the low-side transistor Tr3 are simultaneously turned on, the motor 2 Current flows from the connection point B to the connection point A, whereby the motor 2 can be rotated (closed rotation) in the direction in which the throttle valve 1 is closed. Conversely, if the high-side transistor Tr2 and the low-side transistor Tr4 are turned on at the same time, a current flows from the connection point A to the connection point B with respect to the motor 2 to move the motor 2 in a direction to open the throttle valve 1. (Open rotation).

In order to control the rotational position of the motor 2 (and thus the opening of the throttle valve 1), the current Im flowing through the motor 2 may be controlled. For example, when the motor 2 is to be closed and rotated, the high-side transistor Tr1 is kept in the on state, the low-side transistor Tr4 is kept in the off state, and the low-side transistor Tr3 and the high-side transistor Tr2 are turned on and off. This is performed by alternately switching off states.

That is, the N-channel transistor Tr
1, Tr2, Tr3, and Tr4 are turned on when the drive signals O1, O2, O3, and O4 input to the gates are at a high level (hereinafter, referred to as "H level"). As shown in FIG. 3, during the closed rotation, the drive signal O1 of the transistor Tr1 is set to the H level,
By holding the drive signal O4 of the transistor Tr4 at a low level (hereinafter, referred to as “L level”), the transistor Tr1 is turned on and the transistor Tr4 is turned off. Then, the transistors Tr2 and Tr3 include:
By inputting drive signals O2 and O3 of different levels, which are duty-controlled in accordance with the target throttle opening, the on / off states of the transistors Tr2 and Tr3 are alternately inverted (duty drive).

As a result, when the drive signal O2 goes low and the drive signal O3 goes high, the transistor Tr2 is turned off and the transistor Tr3 is turned on.
The motor current Im increases in the negative direction (that is, the current flowing from the connection point B to the connection point A increases). When the drive signal O2 is at the H level and the drive signal O3 is at the L level and the transistor Tr2 is turned on and the transistor Tr3 is turned off, the magnetic energy (arc extinguishing energy) accumulated in the motor 2 causes the transistor Tr2 to turn off. Tr
1, Tr2 and the motor 2 cause a circulating current to flow through a closed circuit (a circulating circuit) formed on the high side, and the motor current I
m decays.

On the other hand, when the motor 2 is opened, the drive signal O2 of the transistor Tr2 is set to H level as shown in FIG.
By keeping the drive signal O3 of the transistor Tr3 at the L level, the transistor Tr2 is turned on and the transistor Tr3 is turned off. By inputting drive signals O1 and O4 of different levels, duty-controlled according to the target throttle opening, to the transistors Tr1 and Tr4,
The on / off states of r1 and Tr4 are alternately reversed (duty drive).

As a result, when the drive signal O1 goes low and the drive signal O4 goes high, the transistor Tr1 is turned off and the transistor Tr4 is turned on.
The motor current Im increases. Then, the drive signal O1 becomes H
When the transistor Tr1 is turned on and the transistor Tr4 is turned off when the level and the drive signal O4 become L level, the transistors Tr1, Tr2 and the motor 2 are driven by the magnetic energy (arc extinguishing energy) accumulated in the motor 2. A circulating current flows through the formed circulating circuit, and the motor current Im also attenuates.

That is, the two transistors Tr1 and Tr2 on the high side are used for selecting the energizing direction, and the two transistors Tr3 and Tr4 on the low side are used for controlling the energizing time. In both cases of the closed rotation and the open rotation, the motor 2 includes the transistor Tr3
A torque corresponding to the on / off time ratio (duty ratio) of the transistor Tr4 (during open rotation) or the transistor Tr4 (during open rotation) is generated, and the opening of the throttle valve 1 is rotated to a desired position.

The drive logic unit 21 outputs a signal (for example, an H level signal of 5 V or an L level signal of 0 V) for turning on / off each of the transistors Tr 1 to Tr 4 based on a control signal from the microcomputer 11. Pre-driver 2
2a, 22b, 22c and 22d. The pre-drivers 22a, 22b, 22c, and 22d output signals from the driving logic unit 21 to the respective transistors T.
r1 to Tr4 are voltages that can actually be driven (for example,
The level is raised to an H level signal of 12 V or 20 V (when driving the high side transistor) or an L level signal of 0 V) and output to the transistors Tr1 to Tr4 as drive signals O1 to O4, respectively.

Further, the current detection circuit 13 includes the operational amplifier 1
3a and the resistors R7 to R11. Based on the voltage across the resistor R11 inserted in series in the energizing path of the motor 2, the motor 2 or an abnormality in the H-bridge circuit for driving the motor 2 (disconnection, Short circuit).
The output (abnormality detection signal) from the current detection circuit 13 is
The input to the drive logic unit 21 and the drive logic unit 21
Is such that when the current flowing through the motor 2 exceeds a predetermined upper limit, each transistor Tr1
To Tr4. The output from the current detection circuit 13 is divided by resistors R5 and R6,
When an abnormality occurs, the microcomputer 11 stores the occurrence of the abnormality as a diagnosis code and turns on a warning light (not shown) provided on an instrument panel in the cab to drive the occurrence of the abnormality. Also inform others.

Incidentally, the motor drive circuit 1 of the present embodiment
When the energization of the motor 2 is controlled by turning on and off the four transistors Tr1 to Tr4 as shown in FIG. 2, when the transistors Tr1 to Tr4 are energized (on), the on-resistance of each transistor Tr1 to Tr4 is controlled. As a result, a power loss occurs inside the element, and as a result, heat is generated. Therefore, it is necessary to appropriately release the heat generated in each of the transistors Tr1 to Tr4 to the outside when energized.

In this case, each of the transistors Tr1 to Tr4
Of course, a general heat radiation method such as providing a separate heat radiator is also possible, but in this case, the problem described in the related art arises. Therefore, in the present embodiment, focusing on the fact that all four transistors Tr1 to Tr4 are not turned on at the same time, for example, the two transistors Tr3 and Tr4 on the low side are placed close to the substrate as shown in FIG. And implemented. FIG. 4A is an explanatory view showing a state where two transistors Tr3 and Tr4 on the low side are mounted on a substrate, and FIG. 4B is a schematic view of a cross section AA in FIG. FIG.

As shown in FIG. 4B, the transistor T
r4 is a surface mounting component molded with resin, and the back surface (drain) of the transistor chip B4 is directly joined to a metal drain terminal D4. The drain terminal D4 also has a role as a heat sink for radiating heat generated from the transistor chip B4.

Surface (source) of transistor chip B4
Is a metal source terminal S by wire bonding W4.
4 is connected. Although not shown, the gate of the transistor chip B4 is also connected to a metal gate terminal G4 by wire bonding.
The entire component including the transistor chip B4 and the wire bonding W4 is covered with a package M4 formed by resin molding.

The other three transistors Tr1, Tr
2, Tr3 is also a surface mount mold component having a structure completely similar to that of the transistor Tr4, and therefore, detailed description is omitted. Then, the two transistors Tr3 and Tr4 on the low side are mounted close to each other on the substrate 44 as shown in FIG.
Drain terminal D3, source terminal S3, gate terminal G3
Are the lands LD3 and L3 formed on the substrate 44, respectively.
Soldered to S3 and LG3. Transistor T
The drain terminal D4, the source terminal S4, and the gate terminal G4 of r4 are also the lands LD formed on the substrate 44, respectively.
4, LS4, and LG4. Substrate 44
Is a well-known double-sided printed circuit board having a desired copper foil pattern (including lands) formed on both sides of a plate-shaped insulator.

The drain terminals D3 and D4 of the transistors Tr3 and Tr4 are formed on a wiring pattern (copper foil pattern) PD on the substrate 44, on which a resist is applied.
3, a predetermined lead 45 of the connector 45 via the PD 4
a, 45b, and is connected to the motor 2 (not shown in FIG. 4) via the connector 45.
Each of the wiring patterns PD3 and PD4 is formed in a wide range as shown in FIG. 4 in order to improve conduction of heat generated from each of the transistors Tr3 and Tr4 (to be described in detail later), and both are close to each other. It is formed as follows.

On the other hand, the source terminals S3 and S4 are electrically connected via wiring patterns PS3 and PS4, through holes 46a and 46b, and a wiring pattern PG34 formed on the back surface of the substrate 44. This source terminal S3,
S4 and the gate terminals G3 and G4 are all wired to predetermined portions on the substrate 44 via a wiring pattern (not shown), but the details thereof are omitted here.

A copper foil pattern PT is formed on the back surface of the substrate 44 in a range corresponding to the back surface of each of the transistors Tr3 and Tr4. Since the copper foil pattern PT is not for transmitting an electric signal, the copper foil pattern PT is not electrically connected to other components, wiring patterns, and the like, and as will be described later, a heat radiating portion of the two transistors Tr3 and Tr4. (Drain terminals D3, D4) are provided to improve conduction of heat generated from the drain terminals D3 and D4.
Together with the wiring patterns PD3 and PD4, it corresponds to the heat conducting member of the present invention.

As described above, since the power supply to the motor 2 is controlled by the four transistors Tr1, Tr2, Tr3, Tr4, when power is supplied to each transistor, heat is generated inside the element (transistor chip). Therefore, the two transistors Tr3 and Tr4 mounted close to each other also
Although heat is generated at the time of energization, two transistors Tr
3. No current is continuously supplied to Tr4 at the same time. That is, as described with reference to FIG. 3, when the motor 2 is closed, the transistor Tr4 is always off, and the transistor Tr4 is turned off.
By controlling the duty of the motor 3, the amount of current supplied to the motor 2 is controlled. On the other hand, when the motor 2 is open, the transistor Tr3 is always off, and the transistor Tr4
, The amount of current supplied to the motor 2 is controlled.

That is, since one of the transistors is always turned off and the other transistor is energized, heat is generated only from one of the energized transistors while the motor 2 is driving. become. Therefore, as shown in FIG. 4, the two transistors Tr3,
By mounting the transistor Tr4 close to the transistor (in other words, the drain terminals D3 and D4 as the heat radiator) close to each other, the heat generated from the active transistor is transmitted to the heat radiator (drain terminal) of the inactive transistor. If this is the case, the heat dissipation from the transistor will be better performed.

Here, when the two transistors Tr3 and Tr4 are closely mounted on the same surface of the substrate 44 as described above, the drain terminals D3 and D4 are not directly thermally connected to each other, so that the operation is not performed. The heat generated from the transistor in the middle is transmitted through the substrate 44 in the horizontal direction to the inactive transistor through the insulator constituting the substrate 44 directly. However, the insulator (eg, glass cloth epoxy) of the substrate 44 has a higher thermal resistance and is less likely to conduct heat than metals such as copper.

Therefore, in the present embodiment, a copper foil pattern PT for heat conduction is provided on the back surface of the substrate 44, and heat conduction between the two transistors Tr3 and Tr4 is performed through this, so that heat is generated. Good conduction was achieved.
That is, by providing the copper foil pattern PT, the heat generated from one of the active transistors is more likely to be conducted in the thickness direction of the substrate 44 (that is, Conduction is faster and more efficient (to the back side of 44). For example, the transistor Tr
The heat generated from the transistor chip B4 is transmitted from the drain terminal D4 to the land LD4.
Heat is dissipated to D4. Then, the heat conducted to the wiring pattern PD4 around the drain terminal D4 as described above is also transmitted to the copper foil pattern PT on the back surface through the substrate 44.

Since the copper foil pattern PT has a smaller thermal resistance than the insulator of the substrate 44, heat is rapidly transmitted to the entire copper foil pattern PT. The heat transmitted to the entire copper foil pattern PT
Again through the insulator of the substrate 44, it is transmitted to and absorbed by the heat radiating portion (drain terminal D3) and the wiring pattern PD3 of the transistor Tr3 mounted in proximity.

That is, as compared with the case where heat is conducted through the insulator of the substrate 44 in the horizontal direction of the substrate 44 simply by being mounted in close proximity to each other, the use of the copper foil pattern PT on the back surface of the substrate 44 When the heat conduction is performed two-dimensionally (in the thickness direction of the substrate 44), the heat can be more effectively conducted.

Therefore, according to the throttle control system of this embodiment, the two transistors Tr3 and Tr4, which are not continuously energized, are mounted close to each other on the substrate 44, and the drain terminals D3 and D4 are connected to each other. Electrically and thermally connected wiring patterns PD3, PD4 were formed so as to be as wide as possible and as close as possible, and a copper foil pattern PT was provided on the back surface of substrate 44 in a range corresponding to the back surface of transistors Tr3, Tr4. Thus, heat generated from the active transistor can be conducted and absorbed by the non-operating transistor through the insulator of the substrate 44 and the copper foil pattern PT.

As a result, the temperature of the transistor during operation is reduced, and more current can flow through the transistor by the effect of the temperature reduction. In other words, a transistor with a large on-resistance and a smaller chip size can be used in a smaller package with a low allowable loss. Therefore, the cost of the transistor can be reduced, and as a result, the entire electronic control device 5 can be reduced in size and cost.

Further, since the copper foil pattern PT is provided only for heat conduction, it can be used in combination with other signal wiring such as a power supply line and a ground line. [Second Embodiment] The configuration of the throttle control system of the present embodiment is the same as the configuration of the throttle control system of the first embodiment (FIGS. 1 and 2), and a description thereof will be omitted. Hereinafter, the configuration of the throttle control system of the present embodiment will also be described based on FIGS. 1 and 2 of the first embodiment.

In this embodiment, as shown in FIG. 5, during the closed rotation, the driving signal O3 of the transistor Tr3 is held at the H level and the driving signal O2 of the transistor Tr2 is held at the L level, so that the transistor Tr3 is turned on. State, the transistor Tr2 is turned off. The transistors Tr1 and Tr4 have driving signals O of different levels, which are duty-controlled according to the target throttle opening.
1 and O4, the transistors Tr1 and Tr4 are input.
The on / off state of Tr4 is alternately inverted (duty drive).

As a result, when the drive signal O1 is at the H level and the drive signal O4 is at the L level, and the transistor Tr1 is turned on and the transistor Tr4 is turned off,
The motor current Im increases in the negative direction (that is, the current flowing from the connection point B to the connection point A increases). When the drive signal O4 goes high and the drive signal O1 goes low to turn on the transistor Tr4 and turn off the transistor Tr1, the magnetic energy (arc-extinguishing energy) accumulated in the motor 2 causes the transistor Tr4 to turn off. Tr
3, a circulating current flows through a circulating circuit formed on the low side by the Tr 4 and the motor 2, and the motor current Im attenuates.

On the other hand, when the motor 2 is opened, the drive signal O4 of the transistor Tr4 is set to H level as shown in FIG.
By keeping the drive signal O1 of the transistor Tr1 at the L level, the transistor Tr4 is turned on and the transistor Tr1 is turned off. When the drive signal O3 goes low and the drive signal O2 goes high to turn off the transistor Tr3 and turn on the transistor Tr2, the motor current Im increases. When the driving signal O3 goes high and the driving signal O2 goes low to turn on the transistor Tr3 and turn off the transistor Tr2, the magnetic energy (arc-extinguishing energy) accumulated in the motor 2 causes the transistor Tr3 to turn off. A circulating current flows through a circulating circuit formed by Tr3, Tr4 and the motor 2, and the motor current Im also attenuates.

That is, in the present embodiment, contrary to the first embodiment, the two high-side transistors Tr1, T
r2 is used for controlling the conduction time, and the two transistors Tr3 and Tr4 on the low side are used for selecting the conduction direction. When the motor 2 is energized as described above, for example, the high-side transistors Tr1, T2
One of r2 is always off. Therefore, if both transistors can be arranged on the substrate so that the heat generated from the energized transistor is absorbed by the non-energized transistor, the heat radiation performance is improved and the size of the transistor chip can be further reduced.

Therefore, in this embodiment, the two high-side transistors Tr1 and Tr2 are mounted close to each other on the substrate as shown in FIG. FIG. 6A is an explanatory view showing a state in which two high-side transistors Tr1 and Tr2 are mounted on a substrate, and FIG.
It is explanatory drawing showing the outline of section AA in (a).
Note that also in the present embodiment, the four transistors Tr1
Since the structure of Tr4 is the same as the structure shown in FIG. 4 in the first embodiment, the description is omitted here.

Two transistors Tr on the high side
1 and Tr2 are mounted on the substrate 61 in close proximity to each other as shown in FIG. 6A, and the drain terminal D1, the source terminal S1, and the gate terminal G1 of the transistor Tr1 are formed on the substrate 61, respectively. Lands LD1, LS1, LG
1 soldered. The drain terminal D2, the source terminal S2, and the gate terminal G2 of the transistor Tr2 are also connected to lands LD2, LS2,
Soldered to LG2.

On the other hand, since the drain terminals D1 and D2 of the transistors Tr1 and Tr2 have the same potential (see FIG. 2), the two drain terminals D and D2 are connected via the wiring pattern PD60.
1 and D2 are electrically connected. The wiring pattern PD60 also has a function as a heat conducting member of the present invention, as described later. The drain terminals D1 and D2 are connected to the battery 6 via a wiring pattern (not shown), and the gate terminals G1 and G2 are also wired to predetermined portions on the substrate 61 via a wiring pattern (not shown). The details are omitted.

As described with reference to FIG. 5, the two transistors Tr1 and Tr2 are not continuously energized at the same time. When the motor 2 is driven, one of the transistors is always off and the other transistor is turned off. Electricity is applied to this. That is, heat is generated only from one of the energized transistors.

Therefore, in the present embodiment, two transistors Tr1 and Tr1 are connected via the wiring pattern PD60.
By conducting heat conduction between the two, it was possible to conduct heat well. That is, the wiring pattern PD60 necessary for the electrical connection between the two drain terminals D1 and D2 is
By forming the wiring between the two drain terminals D1 and D2 at the shortest distance and thickly, the transistor Tr
1. Used as a heat conducting member for performing good heat conduction between Tr2.

Therefore, according to the throttle control system of the present embodiment, the two transistors Tr1 and Tr2, which are not continuously energized, are mounted close to each other on the substrate 61, and the two drain terminals D1 and D2 Are connected by the wiring pattern PD60, the heat generated by the operating transistor is mainly due to the wiring pattern PD6.
Through 0, the heat can be satisfactorily conducted to and absorbed by the heat dissipation portion (drain terminal) of the non-operating transistor. Therefore, the temperature of the transistor during operation is reduced, and the same operation and effect as those of the first embodiment can be obtained.

Further, in this embodiment, the copper foil pattern P is used only for conducting heat as in the first embodiment.
It is not necessary to provide T, etc., and the wiring pattern P
Since D60 can be effectively used as a heat conducting member, the electronic control device 5 can be further reduced in size and cost.

The embodiments of the present invention are not limited to the above-described embodiments, and it goes without saying that various forms can be adopted as long as they fall within the technical scope of the present invention. For example, in the first embodiment, the low-side transistors Tr3 and Tr4 are mounted close to the same surface of the substrate 44. For example, as shown in FIG.
1 may be mounted on the front and back surfaces so as to sandwich the substrate 71.
In this way, the heat radiating portions (the drain terminals D) of the transistors Tr3 and Tr4 on the substrate 71 without the intervention of the copper foil pattern PT as shown in FIG.
(3, D4), heat is conducted directly and planarly in the thickness direction of the substrate 71 at the portion (corresponding to the heat conducting member of the present invention). The wiring patterns PD71 and PD72 connected to the drain terminals can be made smaller, and the transistors Tr3 and Tr3 can be made smaller.
4 also greatly reduces the mounting area. Therefore, the electronic control device 5 can be further reduced in size and cost.

Similarly, in the second embodiment, the high-side transistors Tr1 and Tr2 are mounted close to the same surface of the substrate 61. For example, as shown in FIG.
It may be mounted on the front and back surfaces of the substrate 61 so as to sandwich the substrate 61. In this case, the drain terminals D3 and D4 are at the same potential and are electrically connected through the through-hole 82. However, since heat can be conducted through the through-hole 82, the And the mounting area of the transistors Tr3 and Tr4 is greatly reduced, so that the electronic control device 5 can be further miniaturized.
The price can be reduced.

When the two transistors are mounted on both sides of the substrate as described above, it is preferable to mount the two transistors such that the heat radiation portions (drain terminals) of the two transistors are completely opposed to each other via the substrate. The present invention is not limited to this, and in consideration of the heat radiation performance of components, the transistors may be mounted so that only a part of the heat radiating portions of both transistors face each other.

In the first embodiment, the case where the low-side transistors Tr3 and Tr4 are mounted close to each other is described. However, the high-side transistors Tr1 and T4 are mounted.
Similarly, r2 may be mounted close to each other. In this case, for example, when the motor 2 is to be closed and rotated, the transistor Tr1 is always turned on and the transistor Tr2 is duty-driven, so that during the energization period to the motor 2, a period occurs in which both the transistors Tr1 and Tr2 are turned on. . However, since the transistor Tr2 has a non-conduction period, heat generated from the transistor Tr1 can be absorbed by the transistor Tr2 during the non-conduction period.

Conversely, when the motor 2 is to be opened, the transistor Tr2 is always turned on and the transistor Tr1 is turned on.
In order to drive the duty, two transistors Tr
1 and Tr2 are both turned on, but during the non-conduction period of the transistor Tr1, the transistor Tr2
Can be absorbed by the transistor Tr1.

That is, while the motor 2 is being driven, one of the two transistors mounted close to each other does not necessarily have to be resting, and one of the two transistors is not continuously energized. It is only necessary that the transistors have a non-conduction period.

Therefore, the low-side transistor Tr
3, Tr4 and the high-side transistor Tr1,
If all the transistors Tr2 are mounted close to each other, all four transistors can be reduced in size and cost, and the entire electronic control device 5 can be further reduced in size and cost, which is more effective.

In particular, the low-side transistor Tr
When the transistors Tr3 and Tr4 are mounted close to each other, one of the two transistors is always turned off, and there is no period in which both are energized at the same time. Therefore, heat dissipation is higher than that of the transistors Tr1 and Tr2 on the high side. Well done.
Also in the second embodiment, it is needless to say that the low-side transistors Tr3 and Tr4 may be mounted close to each other, as in the above-described case.

The high-side transistor Tr
The present invention is not limited to the close mounting of the transistors Tr1 and Tr2 or the close mounting of the transistors Tr3 and Tr4 on the low side, and any one of the transistors on the high side and the one on the low side may be mounted close to each other.

Further, the number of transistors mounted close to each other is not limited to two. For example, three transistors may be close to each other, and it is only necessary that all transistors mounted close to each other be continuously supplied with current. Further, in the above-described embodiment, the transistors Tr1 to Tr4 provided in the motor drive circuit 12 for driving one motor 2 are mounted in close proximity to each other.
In addition, when there is a load and a drive element (transistor or the like) for controlling the energization of the load, even if the drive element and one of the transistors of the motor drive circuit 12 are mounted close to each other. Good.

That is, the present invention is applied not only between the elements for controlling the energization of one control target (load) but also between the elements for individually controlling the energization of a plurality of control targets. Can be. Further, the present invention is not limited to a device for driving a DC motor as in the above-described embodiment, but is applied to any drive device, a control device, or the like having a plurality of heating elements, such as a stepping motor drive device or an injector drive device. be able to.

Further, in the above embodiment, the present invention is applied to the four transistors (FETs) constituting the H-bridge circuit. However, the present invention is not limited to the FETs. For example, all power devices such as bipolar power transistors and thyristors can be used. In addition to these active elements, a passive element such as a resistor or a solenoid may be used, and the present invention can be applied to any heat generating element regardless of whether it is active or passive.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating a configuration of a throttle valve control system to which the present invention is applied.

FIG. 2 is a schematic configuration diagram illustrating a configuration of an electronic control device.

FIG. 3 is a time chart illustrating an energization pattern to a motor by an H-bridge circuit according to the first embodiment.

FIG. 4 is an explanatory diagram illustrating a state in which two low-side transistors are mounted on a substrate according to the first embodiment;

FIG. 5 is a time chart showing an energization pattern to a motor by an H-bridge circuit according to a second embodiment.

FIG. 6 is an explanatory diagram illustrating a state in which two high-side transistors are mounted on a substrate according to the second embodiment.

FIG. 7 is an explanatory diagram illustrating another example of the first embodiment in a state where two low-side transistors are mounted on a substrate.

FIG. 8 is an explanatory diagram illustrating another example of the second embodiment in a state where two high-side transistors are mounted on a substrate.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Throttle valve, 2 ... Motor, 3 ... Throttle opening sensor, 4 ... Pedal position sensor, 5 ... Electronic control device,
6 ... battery, 7 ... ignition switch, 8 ... accelerator pedal, 11 ... microcomputer, 12 ... motor drive circuit, 1
3: current detection circuit, 21: drive logic unit, 22a, 2
2b, 22c, 22d ... pre-drivers, 44, 61, 7
1,81 ... board, 45, 63, 73, 83 ... connector,
46a, 46b, 82: through hole, B1, B4: transistor chip, M1, M4: package, W1, W
4: Wire bonding, LD1 to LD4, LS1 to L
S4, LG1 to LG4, LD73, LD74, LD8
1, LD82: Land, PD3, PD4, PD60, P
D71, PD72, PD81, PD82, PS3, PS
4, PG34: wiring pattern, PT: copper foil pattern

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3G065 CA00 DA05 DA06 DA15 GA00 GA08 GA09 GA27 GA41 GA46 HA21 HA22 JA04 JA11 KA02 5H530 AA12 BB18 DD02 DD14 GG05 GG08 5H570 AA21 BB04 CC04 DD06 EE01 GG01 HA08 HB12 MM03

Claims (6)

[Claims] 1. A driving device having a plurality of heating elements provided in an energization path to one or a plurality of electric loads, wherein at least two of the plurality of heating elements which are not continuously energized with each other. A driving device for an electric load, wherein the two heating elements are mounted close to each other on a substrate, and a heat conducting member is provided between the heating elements mounted close to each other. 2. The electric load driving device according to claim 1, wherein the heat conductive member is a wiring pattern formed on a substrate. 3. The electric load according to claim 1, wherein the plurality of heating elements mounted close to the substrate are switching elements that conduct / cut off a current path of the electric load. Drive. 4. The heating element according to claim 1, wherein the plurality of heating elements mounted close to the substrate are mounted on front and back surfaces of the substrate so as to sandwich the substrate. A driving device for an electric load according to claim 1. 5. The electric load is a single motor, the plurality of heating elements are four switching elements forming an H-bridge circuit capable of controlling a direction of current to the motor, and the four switching elements are The two switching elements, which are not continuously energized, are mounted close to each other.
A drive device for an electric load according to any one of the above. 6. The two switching elements mounted close to each other are connected to one of the positive and negative polarities of the power supply of the motor, and when energizing the motor, 6. The electric load driving device according to claim 5, wherein one of the two switching elements is always turned off and the other is duty-controlled in order to control the direction and magnitude of the energizing current. .