JP2003013796A - Electronic control device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a proper fail-safe function while simplifying constitution and reducing cost. SOLUTION: An ECU 10 is furnished with a main CPU 11 to practice engine control and a sub CPU 12 to practice throttle control. The sub CPU 12 computes a throttle opening command value necessary for the throttle control and outputs a control signal to a driver IC 14 in accordance with its computed result. An electric power source shut-off circuit 15 is provided between the driver IC 14 and a constant voltage electric power source Vcc. The driver IC 14 is furnished with a control circuit 16 to which the constant voltage electric power source Vcc is supplied and a driving stage circuit 17 of its subsequent stage. Supply of the constant voltage electric power source Vcc to the control circuit 16 is shut off by the electric power source shut-off circuit 15 at the time when abnormality is generated in a control system including each of the CPUs 11, 12. Consequently, driving of a throttle motor 22 is stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic control device for a vehicle, and the control device is embodied as an electronic throttle control device or the like.

[0002]

2. Description of the Related Art As a conventional technique of this type, Japanese Patent Laid-Open No. 7-4
In the electronic throttle control device of Japanese Patent No. 294, a main CPU (engine control module) for performing engine control and a sub CPU for performing throttle control
(Throttle control module) is provided. Further, the throttle valve and the motor are connected via an electromagnetic clutch, and the driving of the motor and the electromagnetic clutch is controlled by the sub CPU. Furthermore, as a fail-safe in the event of a failure of any of the control systems, a motor drive power cutoff circuit for cutting off the power supply to the motor and an electromagnetic clutch drive power supply for cutting off the power supply to the electromagnetic clutch. And a shutoff circuit.

In the above structure, when the control system is normal, power is supplied to the motor driving bridge circuit and the electromagnetic clutch driving circuit via the motor driving and electromagnetic clutch driving power cutoff circuits. On the other hand, when an abnormality occurs in the control system, either the main CPU or the sub CPU outputs a signal to the power cutoff circuit to the electromagnetic clutch driving and motor driving power cutoff circuits. The circuit shuts off power to the motor drive bridge circuit and the electromagnetic clutch drive circuit. As a result, fail-safe is performed when an abnormality occurs.

[0004]

The power cutoff circuit for driving the electromagnetic clutch or for driving the motor described above has no problem in supplying power to the driving circuits (motor driving bridge circuit and electromagnetic clutch driving circuit) ahead of the normal system. In order to be able to supply, it is generally composed of an FET capable of passing a current of 20 amperes or more. In this case, the FET has a problem that the element itself is expensive and the number of assembling steps is high. Further, since the FET generates a large amount of heat due to its current capacity, a heat sink for heat dissipation is required. Therefore, there is a problem that the cost is increased and the mounting area of the circuit board is increased.

The present invention has been made in view of the above problems, and an object thereof is to realize an appropriate fail-safe function while simplifying the configuration and reducing the cost. An electronic control device for a vehicle is provided.

[0006]

According to the first aspect of the present invention, the control amount of the actuator is calculated by the microcomputer, and the output circuit generates the drive signal to the actuator based on the control amount. In this case, the output circuit operates by being supplied with a constant-voltage control power supply.
Then, when an abnormality occurs in the control system including the microcomputer, the power supply cutoff circuit cuts off the supply of the control power supply to the output circuit. When the control power supply to the output circuit is cut off, the drive signal generating function of the output circuit is stopped. Therefore, the drive of the actuator is stopped.

In the present invention, the output circuit has a constant voltage (for example, 5
Since the control power source of V) is used, the current consumption thereof is relatively small, and the power source cutoff circuit can be realized by energizing or interrupting a small current. Therefore, the actuator (motor)
Unlike the conventional device in which a large current flowing through the device is energized or de-energized, the power cutoff circuit can be simplified in configuration. As a result, it is possible to realize an appropriate fail-safe function while simplifying the configuration and reducing the cost.

More specifically, as described in claim 2, the power cutoff circuit has a switching element for connecting and disconnecting an electrical connection between the control power supply and the output circuit, The switching element may be turned on / off by a microcomputer. In this case, it is not necessary to use an expensive element such as an FET for passing a large current as the switching element. Moreover, since heat generation of the element is suppressed, a heat sink for heat dissipation is not required, and the mounting area on the circuit board can be reduced.

According to the third aspect of the present invention, the output circuit is provided at a subsequent stage of the control circuit to which the constant-voltage control power source is supplied, and is provided to the actuator when power is supplied from the vehicle battery. And a drive stage circuit for controlling the energization amount of. The power cutoff circuit cuts off the supply of control power to at least the control circuit. In this case, the power supply is cut off in the control circuit at the stage prior to the drive stage circuit, and there is no need for a configuration in which the power supply path from the vehicle-mounted battery to the drive stage circuit is cut off.

According to a fourth aspect of the present invention, there is provided an electronic control device for a vehicle comprising a plurality of microcomputers, wherein any of the plurality of microcomputers can perform power shutoff by the power shutoff circuit.
In this case, even if an abnormality occurs in any one of the microcomputers, the power supply can be properly cut off by another normal microcomputer.

Also, in the vehicle electronic control unit according to the present invention, which comprises a main microcomputer for engine control and a sub-microcomputer for throttle control, the power can be properly cut off by a normal microcomputer. Like

On the other hand, according to the sixth aspect of the invention, when an abnormality occurs in the control system including the microcomputer, the output of the microcomputer is fixed at a predetermined logic level and all the drive signals are turned off. As a result, similarly to the case of cutting off the supply of the control power supply to the output circuit, the function of generating the drive signal as the output circuit is stopped. Therefore, the drive of the actuator is stopped. In such a case, as in the case of the invention of claim 1, unlike the conventional device in which a large current flowing through the actuator (motor) is energized or de-energized, the structure is simplified and the cost is reduced, and the The fail-safe function can be realized.

More specifically, as the invention of claim 6, as described in claim 7, the output of the microcomputer is fixed to a predetermined logic level in the middle of the signal path from the microcomputer to the output circuit. It is advisable to provide the signal fixing circuit.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) A first embodiment of the present invention will be described below with reference to the drawings. In the present embodiment, the present invention is embodied as an electronic throttle control device for a vehicle-mounted engine, and the control device includes a plurality of CPUs as "microcomputers". The details will be described below.

FIG. 1 is a block diagram showing the outline of an electronic throttle control device. In FIG. 1, an ECU 10 is a main CPU that executes engine control such as fuel injection and ignition.
11 and a sub CPU 12 that performs throttle control, and these CPUs 11 and 12 are connected so that they can communicate in both directions.

The operation of the main CPU 11 is monitored by the monitoring circuit 13. That is, the main CPU 11
A WDC (watchdog clear) signal that repeats ON / OFF at a constant cycle is output to the monitoring circuit 13, and when the monitoring circuit 13 loses the periodicity of the WDC signal, the main C
It is considered that an abnormality has occurred in the PU 11, and the main CPU 11 concerned
A reset signal is output to. Similarly, sub C
The operation of the PU 12 is monitored by the main CPU 11. That is, the sub CPU 12 outputs the WDC signal to the main CPU 11, and the main CPU 11 outputs WD.
When the periodicity of the C signal is broken, it is considered that an abnormality has occurred in the sub CPU 12, and a reset signal is output to the sub CPU 12. The main CPU 11 to the sub CPU 1
Alternatively, the WDC signal may be output to the output terminal 2.

The sub CPU 12 inputs detection signals such as accelerator opening and throttle valve opening, and calculates the throttle opening command value and the like necessary for throttle control. Then, based on the calculation result, a control signal is output to the driver IC 14 as an "output circuit".

The driver IC 14 has a battery power source VB.
In addition to being connected, a constant voltage power supply Vcc is connected.
The constant voltage power supply Vcc is a power supply generated as a control power supply by a power supply circuit (not shown), and its voltage value is lower than the battery voltage (for example, 14 volts) and is about 5 volts. The driver IC 14 is connected to the throttle motor 22 in the throttle actuator 21,
The throttle motor 22 drives a throttle valve (not shown) to adjust the amount of intake air to the engine.

Further, the driver IC 14 and the constant voltage power supply Vc
A power cutoff circuit 15 is provided between the power supply circuit c and the power supply line c. The power supply cutoff circuit 15 supplies or cuts off the constant voltage power supply Vcc to the driver IC 14. The power cutoff circuit 15 is operated by either the main CPU 11 or the sub CPU 12.

Next, detailed configurations of the driver IC 14 and the power cutoff circuit 15 will be described with reference to FIG. As shown in FIG. 2, the driver IC 14 includes a control circuit 16 that receives a throttle opening command signal from the sub CPU 12, and a drive stage circuit 17 that is the subsequent stage. That is, the control circuit 16 receives the throttle opening command signal from the sub CPU 12, generates a motor drive signal based on the opening command signal, and outputs the motor drive signal to the drive stage circuit 17. In addition, the control circuit 16 also has a function of detecting an overcurrent flowing in the drive stage circuit 17 and performing abnormality diagnosis.

The drive stage circuit 17 is a gate circuit G1 to G4 for inputting a motor drive signal output from the control circuit 16.
And an H bridge circuit 18 including transistors Tr1 to Tr4. Gate circuits G1 to G4
A constant voltage power supply Vcc is supplied to the H bridge circuit 18
Is supplied with a battery power source VB.

The power shutoff circuit 15 inputs the power shutoff signals from the main CPU 11 and the sub CPU 12.
A gate circuit 19 and a transistor 20 (switching element) that is turned on or off according to the output of the AND gate circuit 19 are provided. In this case, if the transistor 20 is ON, the constant voltage power supply Vcc is supplied to the control circuit 16 and the gate circuits G1 to G4 of the driver IC 14,
The throttle motor 22 is supplied with the battery power VB and is driven as instructed by the sub CPU 12. In contrast,
If the transistor 20 is off, the constant voltage power supply Vc
The supply of c is cut off, the throttle motor 22 cannot receive the supply of the battery power source VB, and the driving is stopped. In the configuration of FIG. 2, the constant voltage power supply Vcc is supplied to the gate circuits G1 to G4.
B may be supplied.

Next, the main CPU 11 and the sub CPU 1
The power shutdown procedure according to No. 2 will be described with reference to the flowchart of FIG. Here, FIG. 3A shows a power shutoff procedure by the main CPU 11 and FIG. 3B shows a power shutoff procedure by the sub CPU 12, and these processes are carried out at a constant time cycle.

In FIG. 3A, first, step 101
Then, it is determined whether or not there is a system abnormality in the main CPU 11, and in the following step 102, it is determined whether or not there is a system abnormality in the sub CPU 12. At this time, if there is a system-related abnormality such that one of the CPUs cannot correctly capture the various sensor detection values or cannot correctly output the control signal to the various actuators, the occurrence of the abnormality is reported. To be determined. If a system abnormality has occurred, the process immediately proceeds to step 104, where the power shutoff circuit 15 shuts off the power. That is, the transistor 20 in the power cutoff circuit 15 is turned off.
Then, the supply of the constant voltage power supply Vcc to the driver IC 14 (particularly the control circuit 16) is stopped. As a result, the driving of the throttle motor 22 is stopped and a desired fail-safe function can be realized.

If no system abnormality has occurred in each of the CPUs 11 and 12, the process proceeds to step 103 and the sub C
It is determined whether or not there is an abnormal operation of the PU 12. At this time, based on the WDC signal from the sub CPU 12,
Twelve operation abnormalities are determined. And the sub CPU 12
When the abnormality occurs, the process proceeds to step 104, and the power shutoff circuit 15 shuts off the power.

The process of FIG. 3 (b) generally conforms to the process of FIG. 3 (a). In steps 201 and 202, each CP is processed.
It is determined whether or not there is a system abnormality in U, and in step 203, it is determined whether or not there is an operation abnormality in the main CPU 11. In step 203, the main CPU abnormality is determined by the data exchanged between the CPUs 11 and 12 or the presence / absence of the WDC signal from the main CPU 11. And
If either of the steps 201 and 202 is YES or the step 203 is NO, the process proceeds to step 204 and the power shutoff circuit 15 shuts off the power.

According to this embodiment described in detail above, the following effects can be obtained. The control circuit 16 is a constant voltage power supply Vc
Since c (for example, 5 V) is used as a driving power source, its current consumption is relatively small, and the power source cutoff circuit 15 can be realized by energizing or interrupting a small current. Therefore, unlike the conventional device in which a large current flowing through the actuator (motor) is energized or deenergized, the power cutoff circuit 15 can be simplified in configuration. As a result, it is possible to realize an appropriate fail-safe function while simplifying the configuration and reducing the cost.

Particularly in this case, it is not necessary to use an expensive element such as an FET for flowing a large current as the transistor 20 (switching element) in the power cutoff circuit 15. Moreover, since heat generation of the element is suppressed, a heat sink for heat dissipation is not required, and the mounting area on the circuit board can be reduced.

Since power can be cut off by the power cutoff circuit 15 in either the main CPU 11 or the sub CPU 12, even if an abnormality occurs in any one of the CPUs, the power cutoff can be properly performed by another normal CPU.

(Second Embodiment) Next, a second embodiment of the present invention will be described focusing on the differences from the above-described first embodiment. FIG. 4 is a circuit diagram showing the configuration of the driver IC 14 in the present embodiment,
This structure is adopted by replacing the structure shown in FIG. That is, in FIG. 4, the power cutoff circuit 15 is deleted as a difference from FIG. 2, and the control circuit 1 in the driver IC 14 is removed.
6 and the gate circuits G1 to G4 are constantly supplied with the constant voltage power supply Vcc. A signal fixing circuit 3 is newly provided in the middle of the signal path from the sub CPU 12 to the control circuit 16.
1 is provided.

In this configuration, the main CPU 11 or sub C
When an abnormality occurs in the control system including the PU 12, the signal fixing circuit 31 fixes the output of the sub CPU 12 to the logic L level or the logic H level. As a result, all the motor drive signals of the control circuit 16 are turned off. In such a case, as in the case of shutting off the supply of the constant voltage power supply Vcc to the control circuit 16 (first embodiment), the function of generating the drive signal as the control circuit 16 is stopped. Therefore, the driving of the throttle motor 22 is stopped. Incidentally, the signal fixing circuit 31 is configured to be operated by either the main CPU 11 or the sub CPU 12.

However, in the present embodiment, the signal fixing circuit 31 is not provided and the main CPU 11 or the sub CPU 1
The configuration may be such that the output of the sub CPU 12 is forcibly fixed to the logical L level or the logical H level by the step 2.

Also in the present embodiment, as in the first embodiment, unlike the conventional device that energizes or interrupts energization of a large current flowing through the actuator (motor),
It is possible to realize an appropriate fail-safe function while simplifying the configuration and reducing the cost.

The present invention can be embodied in the following modes other than the above. In the above-described embodiment, as shown in FIG. 2 and the like, the driver I is constituted by the control circuit 16 and the drive stage circuit 17.
Although C14 is configured, part or all of the drive stage circuit 17 may be provided outside the driver IC. For example, drive stage circuit 1
7 transistors Tr1 to Tr4 are provided outside the driver IC. In addition, as the configuration of the driver IC 14, from the battery power source VB to the constant voltage power source V in the driver IC 14.
It may be configured to generate cc. In this case, a power cutoff circuit 15 is provided in the constant voltage power supply line including the battery power supply VB and the constant voltage power supply Vcc, and the power supply cutoff circuit 15 cuts off the supply of the constant voltage power supply Vcc to the control circuit 16. That is, in each of the above constant voltage power supply lines, current consumption is small, and the above-described excellent effects can be obtained. The power cutoff circuit 15 may be provided inside or outside the driver IC 14.

When the throttle actuator has an electromagnetic clutch at least between the throttle valve and the motor, the driver IC side for driving the electromagnetic clutch also has a power cutoff circuit (for example, the power cutoff circuit 15 in FIG. 2). Can be adopted. In such cases,
When an abnormality occurs in the control system, a driver IC for the electromagnetic clutch
The power supply cutoff circuit cuts off the supply of the constant voltage power supply Vcc to the (output circuit). As a result, the above-mentioned excellent effects can be obtained.

In the above embodiment, the ECU has two CPs.
Which CPU is equipped with U (microcomputer)
However, although the power supply can be cut off, the present invention is not limited to this. For example, it may be embodied as an ECU having a single CPU (microcomputer).
Further, the invention can be applied to other than the electronic throttle control device.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an outline of an electronic throttle control device.

FIG. 2 is a circuit diagram showing a detailed configuration of a driver IC and a power cutoff circuit.

FIG. 3 is a flowchart showing a power shutoff procedure by a main CPU and a sub CPU.

FIG. 4 is a circuit diagram showing a detailed configuration of a driver IC in the second embodiment.

[Explanation of symbols]

10 ... ECU, 11 ... Main CPU, 12 ... Sub CP
U, 14 ... Driver IC, 15 ... Power cutoff circuit, 16 ...
Control circuit, 17 ... drive stage circuit, 18 ... H bridge circuit,
20 ... Transistor, 21 ... Throttle actuator, 22 ... Throttle motor, 31 ... Signal fixing circuit.

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3G065 CA38 CA40 DA04 FA01 KA35                       KA36                 3G084 BA00 BA05 BA11 BA16 DA28                       DA36                 3G301 JB03 JB07 LA03 LC03 NE16                       PA11Z PG02Z

Claims (7)

[Claims] 1. A microcomputer for calculating a control amount of an actuator, and an output circuit for generating a drive signal to the actuator based on the control amount calculated by the microcomputer, the output circuit for controlling a constant voltage. An electronic control device for a vehicle that operates by supplying power, comprising a power cutoff circuit for cutting off the supply of control power to the output circuit, and when an abnormality occurs in a control system including a microcomputer, An electronic control unit for a vehicle, characterized in that the supply of control power to the output circuit is interrupted by a power interruption circuit. 2. The power cutoff circuit has a switching element for connecting and disconnecting an electrical connection between a control power supply and the output circuit, and the switching element is turned on / off by a microcomputer. Item 2. The vehicle electronic control unit according to Item 1. 3. The control circuit, to which the output power of the constant voltage is supplied, is provided in the output circuit, and a drive stage circuit which is provided at a subsequent stage of the output circuit and controls an energization amount to an actuator according to power supply from a vehicle battery. And a power cutoff circuit,
3. The vehicle electronic control unit according to claim 1, wherein the supply of control power to at least the control circuit is cut off. 4. An electronic control unit for a vehicle, comprising a plurality of microcomputers, wherein any one of the plurality of microcomputers can be shut down by the power shutoff circuit. An electronic control unit for a vehicle according to item 1. 5. An electronic control device for a vehicle, comprising: a main microcomputer for controlling an engine; and a sub-microcomputer for controlling a throttle, wherein the output circuit generates a drive signal for a throttle actuator. The electronic control device for a vehicle according to any one of claims 1 to 3, wherein any of the microcomputers is configured to perform power shutoff by the power shutoff circuit. 6. A vehicle electronic control device comprising a microcomputer for calculating a control amount of an actuator, and an output circuit for generating a drive signal to the actuator based on the control amount calculated by the microcomputer, the microcomputer comprising: An electronic control device for a vehicle, wherein when an abnormality occurs in a control system including a computer, the output of the microcomputer is fixed to a predetermined logic level and all drive signals are turned off. 7. An electronic control unit for a vehicle according to claim 6, wherein a signal fixing circuit for fixing the output of the microcomputer to a predetermined logic level is provided in the signal path from the microcomputer to the output circuit. The vehicle electronic control device provided.