JP2001209436A - Cooling device for ecu - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device that controls an internal temperature of ECU below a reference temperature without using a large size heat sink and a large electric fan. SOLUTION: The voltage (+B) from D.C constant voltage power supply is converted into two level constant voltage by a transistor 24 and a voltage switching part 25 and is supplied to inside of a ECU 20 as a power supply voltage Vth. The internal temperature of the ECU 20 is measured by a thermister 23, in the case that measured internal temperature of the ECU 20 exceeds a reference temperature, the power supply voltage Vth is changed towarda small consumption power of the transistor 24, then the internal temperature makes low. Further, the internal electric current value makes low by changing the control mode, the internal temperature makes further lower.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ECU cooling device for lowering the internal temperature of an electronic control unit called an ECU, and more particularly, to the control of the internal temperature of an ECU used for controlling a power train of a vehicle equipped with an engine. The present invention relates to an ECU cooling device suitably used for management.

[0002]

2. Description of the Related Art In a vehicle equipped with an engine, a power train such as an engine and a transmission is provided with an E.
It is controlled extensively and collectively by the CU. EC
U is usually mounted in the engine room of the vehicle, but since the engine room is in a severe environment, the ECU mounted in the engine room has a thermal environment for preventing overheating. Protective measures are needed. In particular, it is important to protect the regulator, which is a large heat source in the ECU.

That is, in an ECU for controlling a power train of a vehicle equipped with an engine, a battery voltage (14
V) is converted into a constant power supply voltage of about 5 V by a regulator using a transistor and supplied to the ECU, and various devices including the CPU in the ECU are driven by the power supply voltage. The transistor constituting the regulator generates a large amount of heat among various devices in the ECU, and it is important to suppress the temperature to be equal to or lower than the allowable upper limit of the junction temperature in order to prevent destruction.

As a protection measure, conventionally, a transistor constituting a regulator is attached to a heat sink to promote heat dissipation of the transistor. Further, an electric fan provided in the engine room lowers the temperature in the engine room to promote heat radiation of the heat sink.

Japanese Patent Application Laid-Open No. H11-198492 discloses that a thermistor is brought into contact with a heat sink for fixing a transistor (FET), and the number of rotations of an electric fan is controlled based on a temperature signal output from the thermistor. There is disclosed a configuration for cooling to prevent a rise in temperature of an electronic device.

[0006]

However, in each of the above-described configurations, the EC in the thermally severe engine room is not provided.
In order to effectively cool U, especially the transistor constituting the regulator, a large heat sink having good heat dissipation is required, and a large electric fan is required.

There is no particular problem if there is room in the engine room, but in recent vehicles, the space in the engine room is small, and a large ECU having a heat sink with good heat dissipation, a large electric motor, It is not easy to provide a fan or the like. Therefore, there is a demand for downsizing of a device for cooling the inside of the engine room.

The present invention has been made to solve such a problem. It is an object of the present invention to control the internal temperature of an ECU to a reference value or less without depending on the enlargement of a heat sink and the size of an electric fan. An object of the present invention is to provide an ECU cooling device.

[0009]

SUMMARY OF THE INVENTION An ECU cooling apparatus according to the present invention has an EC having an internal power supply which converts a voltage from a DC constant voltage power supply to a constant voltage by a transistor and supplies the same to the inside.
An ECU cooling device for lowering the internal temperature of U,
Temperature measuring means for measuring the internal temperature of the CU; and when the internal temperature of the ECU measured by the temperature measuring means exceeds a reference temperature, a power supply voltage in the ECU is changed in a direction to reduce power consumption of the transistor. And means for performing the above, whereby the above object is achieved.

Further, the ECU cooling device of the present invention is an ECU cooling device for converting the voltage from a DC constant voltage power supply to a constant voltage by a transistor and lowering the internal temperature of an ECU having an internal power supply to be supplied to the inside. Temperature measurement means for measuring the internal temperature of the ECU, means for reducing the internal current value of the ECU by changing the control mode when the internal temperature of the ECU measured by the temperature measurement means exceeds the reference temperature, And the above object is achieved.

The internal temperature of the ECU is affected not only by the external temperature of the ECU but also by the amount of internal heat generated from control devices and the like in the ECU and the power consumption of the transistors. The lower the temperature, the lower the internal temperature. Therefore, the internal temperature can be reduced by changing the power supply voltage in the ECU so that the power consumption of the transistor is reduced.

Further, the power consumption of a transistor is represented by the product of the amount of voltage change by the transistor and the internal current of the ECU. Therefore, by reducing the internal current value of the ECU by changing the control mode, the power consumption of the transistor can be reduced. Power consumption is reduced, and the internal temperature can be reduced.

[0013] By using a combination of the change of the power supply voltage in the ECU and the reduction of the internal current value, or by combining them with an electric fan,
The cooling performance is further improved, and the performance of the ECU is gradually reduced due to a change in the power supply voltage in the ECU and a decrease in the internal current value, thereby alleviating adverse effects on various controls by the ECU.

The change of the control mode for decreasing the internal current value is performed, for example, in a vehicle equipped with an engine.
For example, a change from the normal traveling mode to the power save mode (evacuation traveling mode) is performed. By selecting the power save mode (evacuation traveling mode), the load on a control device such as a CPU mounted in the ECU is reduced, and the internal current value is reduced, so that the power consumption of the transistor is reduced.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a conceptual diagram of an engine room showing how the ECU cooling device of the present invention is mounted. EC of the present invention
The U cooling device is provided to cool an ECU (electronic control device) 20 mounted in an engine room 11 of the vehicle 10 in order to control a power train of the vehicle 10.

The engine room 11 is provided with a power train such as an engine, a motor and a transmission, an ECU 20 for controlling the power and the lane, and an electric fan 30. The electric fan 30 is provided in the engine room 1
1, the outside air is sucked into the engine room 11 from the front of the vehicle 10 through the radiator, so that the cooling water in the radiator, the inside of the engine room 11, the ECU 20 in the engine room 11, etc. Force cooling.

The ECU 20 is disposed at the rear of the engine room 11 in a state housed in a case 40.
Cooling air from the electric fan 30 provided at the front of the engine room is introduced into the case 40 by the duct 41. FIG. 2 is a schematic configuration diagram of the ECU 20. As shown in FIG. 2, the ECU 20 in the engine room 11 for controlling the power train includes a main CPU 21 and a sub CPU 22, a thermistor 23 for measuring the temperature inside the ECU 20, and a transistor 24 for driving various devices. And a regulator as a configured internal power supply.

Transistor 24 Constituting Regulator
Are attached to a heat sink 26 for heat dissipation. The heat sink 26 is connected to the case 4 via the duct 41.
In order to increase the heat radiation effect by the outside air introduced inside
The ECU 2 is disposed so as to face the duct 41,
The transistor 24 is mounted on the surface facing the inside of the transistor 0.

The transistor 24 supplies a constant voltage of a battery voltage (+ B) from, for example, a 14 V battery, which is a DC constant voltage source, to the voltage switching unit 25. 24 is converted into two types of power supply voltages Vth. First level power supply voltage Vt
h is VL corresponding to the normal voltage within the specification of the power supply voltage Vth, and is set to 5.0 V in the present embodiment. The power supply voltage Vth of the second level is VL (5.0
V) higher than VH. VH is an upper limit value in the specification of the power supply voltage Vth or a value close thereto, and is set to 5.5 V in the present embodiment.

That is, the voltage switching unit 25 operates based on an instruction by an electric signal from the outside,
VL (5.0 V) or VH (5.5 V) is generated by controlling the operating state of the main CPU 21 and the sub CPU 22 as the power supply voltage Vth.
To supply. In a state in which VH (5.5 V) is generated, a voltage drop by the transistor 24 is smaller in a state in which VH (5.5 V) is generated than in a state in which VH (5.5 V) is generated.
4 is reduced.

On the other hand, the main CPU 21 and the sub CPU
The control unit 22 executes, for example, opening degree control of an electric throttle 50 provided in an air supply system of an engine, change operation control of an automatic transmission 60, and various other controls on a power train.

The thermistor 23 outputs to the main CPU 21 a signal corresponding to the internal temperature Tecu of the ECU 20, especially the temperature near the transistor 24.

The main CPU 21 controls the internal temperature of the ECU 20 based on an output signal of a thermistor 23 as a temperature measuring means, based on a sub CPU 22, a voltage switching unit 25, an electric fan 30, an electric throttle 50, an automatic transmission 60 and the like. To control the transistor 2 as the internal temperature of the ECU 20.
The chip temperature Tj of No. 4 is not more than the allowable upper limit Tjmax.

The details of this control will be described below with reference to the flowchart of FIG.

In the ECU cooling apparatus, the routine shown in FIG. 3 is executed at a predetermined time, for example, every 16 ms.

In each routine, first, the internal temperature Tec of the ECU 20 detected by the thermistor 23 in step S1.
The data on u is fetched, and the process proceeds to step S2. In step S2, the internal temperature Tecu is compared with its reference temperature T0. The reference temperature T0 is the value of the transistor 2
4 corresponds to the allowable upper limit value Tjmax of the chip temperature Tj.

If the internal temperature Tecu is equal to or lower than the reference temperature T0, the process proceeds to steps S3 and S4. In step S3, the count time Cfa
n is reset. In step S4, the electric fan 3
An off command is sent to 0. The count time Cfan by the time counter corresponds to the elapsed time from the start of operation of the electric fan 30.

When step S4 is completed, step S5
Then, the process sequentially proceeds to step S6. In step S5,
VL (5.
0V) is supplied to the inside of the ECU 20. In step S6, the normal mode is selected as the traveling mode. In the normal mode, the main CPU 21 and the sub CPU 22 perform normal control on the power train. Thereby, the opening degree of the electric throttle 50 and the change operation of the automatic transmission 60 are controlled as usual.

The internal temperature Tecu of the ECU 20 is equal to the reference temperature T.
When the value is maintained at 0 or less, the ECU 20 maintains the normal performance by repeating this routine, and the transistor 24 is only cooled by the outside air naturally introduced into the case 40. This state is called phase 0.

Here, the chip temperature T of the transistor 24
j is represented by the following equation (1). Tj = Ta + ΔTa + Pc (θjc + θca) (1) In the expression (1), Ta is an external temperature of the ECU 20, that is, an atmosphere temperature in the case 40. Also, ΔTa
Is a difference between the internal temperature Tecu of the ECU 20 and the external temperature Ta of the ECU 20, and corresponds to an internal heat generation amount from a control device or the like in the ECU 20. Pc is the transistor 24
Is the power consumption of the regulator composed of θjc
Is the thermal resistance between the transistor chip and the regulator, θ
ca is the thermal resistance between the regulator and the inside of the ECU.

Since the thermal resistances θjc and θca are basically constant, the chip temperature Tj of the transistor 24 changes according to the magnitude of the power consumption Pc of the regulator constituted by the transistor 24. It also changes depending on the magnitude of Ta (the ambient temperature in the case 40).

The power consumption Pc of the regulator constituted by the transistor 24 is expressed by the following (2). Pc = [+ B (14V) −power supply voltage Vth] × ECU internal current (2) The internal current of the ECU 20 in the equation (2) is determined by, for example, the loads on the main CPU 21 and the sub CPU 22.

The above is the case where the internal temperature Tecu of the ECU 20 is maintained at or below the reference temperature T0. By comparing the internal temperature Tecu with the reference temperature T0 in step S2, the internal temperature Tecu exceeds the reference temperature T0. If this is the case, the process moves to step S7, step S8, and step S9 sequentially.

In step S7, the count time Cfan by the time counter is counted up. Step S
At 8, an ON command is given to the electric fan 30. In step S9, the count time Cfan of the time counter is compared with a first reference time t1 (for example, 10 seconds). And the count time C by the time counter
Until the fan reaches the first reference time (for example, 10 seconds) t1, steps S1-S2-S7-S8-S9-S5
-S6 is sequentially repeated. This is called phase 1.

In the phase 1, the electric fan 30 is driven and the outside air is forcibly supplied into the case 40, so that the external temperature Ta of the ECU 20 (the ambient temperature in the case 40) in the equation (1) decreases. , The chip temperature Tj of the transistor 24 decreases.

The count time Cfan by the time counter
However, if the internal temperature Tecu drops below the reference temperature T0 before the first reference time t1 (for example, 10 seconds) is reached, steps S1-S2-S3-S4-S5-S
Step 6 is repeated, that is, the process returns to the phase 0.

Even if the count time Cfan of the time counter reaches the first reference time t1 (for example, 10 seconds), if the internal temperature Tecu continues to exceed the reference temperature T0,
That is, when the phase 1 is continued, the process sequentially shifts to step S9, step S10, and step S11.

In step S10, VH (5.5 V) higher than VL (5.0 V) is set as the power supply voltage Vth by the ECU.
The voltage switching unit 25 is controlled so as to be supplied to the inside of the power supply 20. In step S11, the count time Cfan of the time counter is compared with a second reference time t2 (for example, 20 seconds) which is larger than the first reference time t1 (for example, 10 seconds). The count time Cfan of the time counter is equal to the second reference time t2 (for example, 20
Seconds) until steps S1-S2-S7-S8
-S9-S10-S11-S6 are sequentially repeated. This is called phase 2.

In phase 2, the electric fan 30 is driven, and the outside air is forcibly supplied into the case 40. At the same time, the power supply voltage Vth in the ECU 20 becomes VL (5.0 V)
To VH (5.5 V). As can be seen from the equation (2), when the power supply voltage Vth in the ECU 20 increases, the amount of voltage drop by the transistor 24 decreases, and the load on the transistor 24 is reduced, so that the transistor 24 is configured. The power consumption Pc of the regulator is reduced. As a result, the power consumption Pc (θjc + θca) in the equation (1) decreases, and the chip temperature Tj of the transistor 24 decreases.

For example, in the equation (2), when the internal current of the ECU 20 is 900 mA, the power supply voltage Vth is set to 5.
When the voltage increases by 0.5 V from 0 V (VL) to 5.5 V (VH), the power consumption Pc of the regulator constituted by the transistor 24 decreases from 8.1 W to 7.65 W, and the chip temperature Tj of the transistor 24 theoretically increases. Is 3.1 ° C. lower than in phase 1.

The performance decrease (-α) of the ECU 20 in the phase 2 is slight because VH (5.5 V) is within the specification of the power supply voltage Vth.

If the internal temperature Tecu falls below the reference temperature T0 before the count time Cfan of the time counter reaches the second reference time t2 (for example, 20 seconds), steps S1-S2-S3-S4 are performed. -Repeat S5-S6, that is, return to phase 0.

If the internal temperature Tecu continues to exceed the reference temperature T0 even if the count time Cfan of the time counter reaches the second reference time t2 (for example, 20 seconds), that is, if the phase 2 continues, the process proceeds to step S12. Transition.

In step S12, the power save mode is selected as the running mode. The power save mode is also called a limp mode (fail mode). In the case of the present embodiment, in this mode, the sub CPU 22 is stopped. Further, the energization of the electric throttle 50 is stopped, the opening thereof is fixed at a fixed value, the change operation is stopped for the automatic transmission 60, and the selected gear is fixed to the fourth gear, for example, in the high range. . At the same time, the check engine lamp, which is a warning light, is turned on. This state is called phase 3.

In the phase 3, while the electric fan 30 continues to be driven, the power supply voltage Vth in the ECU 20 becomes VH
(5.5 V), and the load on the ECU 20 is reduced by selecting the power save mode, so that the internal current is reduced. As a result, the power consumption Pc of the regulator constituted by the transistor 24 is further reduced as compared with the case of the phase 2, and the power consumption Pc (θjc + θ) in the equation (1) is obtained.
As ca) further decreases, the chip temperature Tj of the transistor 24 decreases.

Performance degradation of ECU 20 in phase 3 (−
α) is larger than in phase 2, but the internal heat value ΔTa in equation (1) is lower.

For example, the power supply voltage Vth in the equation (2)
Rises from 5.0 V (VL) to 5.5 V (VH) by 0.5 V, and when the internal current of the ECU 20 decreases from 900 mA to 750 mA, the power consumption Pc of the regulator constituted by the transistor 24 becomes 8. From 1 W to 6.38 W, the chip temperature T of the transistor 24 is reduced.
j is theoretically the power consumption Pc compared to the phase 1
The temperature of the ECU 2 is reduced by 12 ° C.
A temperature decrease due to a decrease in the internal heat generation amount ΔTa due to the performance decrease (−α) of 0 is added, and the overall temperature decrease amount is significantly increased.

As described above, the ECU cooling apparatus according to the present embodiment executes the routine shown in FIG.
By repeatedly executing the process every s, the chip temperature Tj of the transistor 24 as the internal temperature of the ECU 20 can be controlled to be equal to or lower than the allowable upper limit value Tjmax.

Further, for the control, phase 1,
Phase 2 and phase 3 are executed in order. In phase 2, the power supply voltage Vth in the ECU 20 is reduced by the power consumption Pc of the regulator constituted by the transistor 24.
In the phase 3, in addition to this, when the running mode is changed, the internal current of the ECU 20 is reduced, so that only the phase 1 is executed, that is, only the driving of the electric fan 30 is performed. , The load on the electric fan 30 is greatly reduced. As a result, the size of the electric fan 30 can be reduced.

Further, the performance of the ECU 20 is reduced step by step, so that there is almost no possibility that the performance of the ECU 20 will be adversely affected. In addition, since it hardly reaches Phase 3 and is usually limited by Phase 2, secondary adverse effects such as a decrease in running performance are slight.

[0052]

As described above, the ECU cooling device according to the present invention has
When the internal temperature of U is measured and the measured internal temperature of the ECU exceeds the reference temperature, the power supply voltage in the ECU is changed so that the power consumption of the transistors constituting the internal power supply decreases. The temperature inside the ECU can be controlled to be equal to or lower than the reference temperature without depending on the electric fan, the heat sink and the like. Therefore, even when an electric fan, a heat sink, or the like is used, it is possible to reduce the size of the fan and improve the economical efficiency, and at the same time, to reduce the EC in the engine room of a thermally severe and narrow car.
A space for installing the U can be secured.

When the measured internal temperature of the ECU exceeds the reference temperature, the internal current value of the ECU is reduced by changing the control mode, so that the ECU does not depend on an electric fan, a heat sink, or the like. Is controlled to be equal to or lower than the reference temperature. Therefore, even when the electric fan and the heat sink are used, they can be downsized, the economic efficiency can be improved, and the ECU in the engine room of a car that is thermally severe and narrow is narrow.
The space for the installation can be secured.

Also, by combining these,
It is possible to increase the cooling performance by limiting the performance of the ECU step by step.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of an engine room showing a mounting state of an ECU cooling device of the present invention.

FIG. 2 is a schematic configuration diagram illustrating an example of an embodiment of an ECU cooling device of the present invention.

FIG. 3 is a flowchart showing an operation of a CPU used in the ECU cooling device of the present invention.

[Description of Signs] 10 Vehicle 11 Engine room 20 ECU 21 Main CPU 22 Sub CPU 23 Thermistor 24 Transistor 25 Voltage switching unit 26 Heat sink 30 Electric fan 40 Case 50 Electric throttle 60 Transmission

Claims (2)

[Claims] 1. An ECU cooling device for lowering an internal temperature of an ECU having an internal power supply for converting a voltage from a DC constant voltage power supply into a constant voltage by a transistor and supplying the voltage to the inside, wherein the internal temperature of the ECU is measured. Temperature measurement means; and means for changing a power supply voltage in the ECU in a direction to reduce power consumption of the transistor when an internal temperature of the ECU measured by the temperature measurement means exceeds a reference temperature. An ECU cooling device, comprising: 2. An ECU cooling device for lowering an internal temperature of an ECU having an internal power supply for converting a voltage from a DC constant voltage power supply to a constant voltage by a transistor and supplying the voltage to the inside, wherein the ECU measures the internal temperature. A temperature measuring means, and when the internal temperature of the ECU measured by the temperature measuring means exceeds a reference temperature, the control mode is changed to E.
Means for lowering the internal current value of the CU.