JP3554568B2 - Control device for internal combustion engine - Google Patents

Description

[0001]
[Industrial applications]
The present invention of a motor vehicle control device, and more particularly, to an improvement of the power supply circuit.
[0002]
[Prior art]
2. Description of the Related Art In recent years, in automobiles and the like, the number of electrical components has been significantly increased due to the addition of high functions and the like, so that multiple harnesses have been adopted in order to simplify and reduce the weight of wire harnesses. In this multiplex harness system, there are a master unit with a built-in microcomputer and a local unit without a microcomputer, and switches, sensors, lamps, motors, etc., which are installed in the vicinity, are mastered in accordance with their respective input / output characteristics. It is connected to a unit or a local unit, connected between the units by multiplex transmission, and output to an output terminal of the terminal unit or the master unit based on input / output information processed by the master unit.
[0003]
As a conventional example, as shown in Japanese Utility Model Publication No. 3-32443, there is a system power supply that reduces the power consumption of a battery as much as possible and stops the power supply to the system when an abnormal voltage is applied.
[0004]
However, as a problem in operating a multi-harness system of an automobile, when a battery loss or a momentary power interruption, which is common, is taken into consideration, the function of the master unit stops before the entire system goes down. When the power supply is restored again, there is a possibility that data or the like of a moving object due to mechanical inertia may be missed while the master unit is stopped.
[0005]
[Problems to be solved by the invention]
Therefore, an object of the present invention is to supply power to at least a microcomputer of a master unit and a communication circuit for multiplex communication with other units at least when a battery is disconnected or an instantaneous interruption occurs. certain of the state to the point to continue to monitor.
[0006]
Another object of the present invention is to prevent the protection power of the master unit from leaking to other units when the battery is disconnected or a momentary interruption occurs.
[0007]
Further, by shutting off the power supply to a part of the master unit, the power supply capability to the necessary part of the master unit is improved.
[0008]
[Means for Solving the Problems]
The above object is achieved by inserting a power supply circuit having a capacitor for supplying power to a microcomputer or a communication circuit between the surge absorbing circuit and the input side capacitor of the voltage regulator in place of the battery when the battery is disconnected or momentary interruption. It is achieved.
[0009]
Specifically, the power supply circuit is a series connection circuit of a Zener diode connected in a forward direction when viewed from the ground and a resistor connected between the power supply line and the ground, and connected between the power supply line and the ground. A series connection circuit of a diode connected in a forward direction as viewed from the ground and the another capacitor,
A connection point between the resistor and the Zener diode and a connection point between the diode and the another capacitor are electrically connected.
[0010]
More specifically, the surge absorbing circuit includes a diode connected in a forward direction as viewed from the terminal side, and a Zener diode connected between a cathode of the diode and ground in a forward direction as viewed from the ground side. It is constituted by.
[0011]
More specifically, the input potential of the surge absorbing circuit is monitored, and when the potential becomes equal to or lower than a predetermined value, power supply to a part of the master unit is cut off.
[0012]
According to the present invention configured as described above, when the battery is disconnected or a momentary interruption occurs, the power is supplied to the master unit from the capacitor of the power supply circuit in addition to the ripple removing capacitor on the input side of the voltage regulator, and the battery is disconnected or The master unit continues to function until the I / O load of the master unit or another unit is electrically or mechanically stopped due to a momentary interruption, thereby preventing data from being skipped.
[0013]
Also, by not supplying power normally, the withstand voltage of the capacitor constituting the power supply circuit can be kept low, and a capacitor with a larger capacity can be used.
[0014]
According to the preferred embodiment, the battery has a function of preventing a current from flowing out of the capacitor of the power supply circuit to another unit at the time of disconnection or momentary interruption, and power can be supplied to the master unit by the capacitor of the power supply circuit for a longer time. .
[0015]
According to another preferred embodiment, the supply of power to unnecessary portions in the master unit is stopped, so that power can be supplied to the master unit by the capacitor of the power supply circuit for a longer time.
[0016]
【Example】
The first embodiment will be described with reference to FIG.
[0017]
The master unit 1 receives power supply from the positive electrode of the battery 2, and is connected to a surge absorbing circuit 3 including a resistor 31 and a zener diode 32.
[0018]
The Zener diode 32 used in the surge absorbing circuit 3 is usually of a voltage of 24 V or more, and has a function of absorbing a surge when an abnormal voltage such as a load dump surge is applied.
[0019]
A voltage regulator 4 is connected next to the surge absorbing circuit 3, and a capacitor 5 in the input section is used for removing a power supply ripple, and a withstand voltage larger than that of the surge absorbing zener diode 32 is used.
[0020]
The capacitor 6 connected to the output of the voltage regulator 4 is for smoothing the output voltage, and usually outputs a voltage of about 5 V for the system power supply in the unit.
[0021]
In the master unit 1, a microcomputer 7 and I / Os (input / output interfaces) 8, 9 are connected.
[0022]
Also the microcomputer 7 a communication circuit 10 for multiplex communication with other local units 11, 12 are connected and controls transmission and reception of data between the local unit 11 or the like by the microcomputer 7.
[0023]
Note that the local units 11 and 12 also have communication circuits 13 and 14, and transmit input signals of the local units 11 and 12, etc., and output signals from the master unit 1 according to signals from the master unit. in response to output to the load. The nearest input / output load is connected to the master unit 1 , the local units 11, 12, and the like.
[0024]
Here, the second power supply 15 is connected in parallel between the surge absorbing circuit 3 and the voltage regulator 4.
[0025]
The circuit of the power supply 15 (that is, the power supply circuit) includes a simple power supply including a resistor 15a and a zener diode 15b for charging the large-capacity capacitor 15C, and a diode 15d for supplying power when the battery is disconnected or momentary interruption. ing.
[0026]
If there is enough space, the capacity of the high voltage (35V) capacitor 5 for absorbing ripple connected to the input side of the voltage regulator 4 may be increased, but it is uneconomical because it is unnecessary during normal operation. Therefore, in this embodiment, a capacitor 15c is separately provided as the second power supply.
[0027]
As the capacitor 15c, a large-capacity capacitor having a low withstand voltage (for example, 16 V) can be used.
[0028]
However, here, when the voltage regulator 4 that operates to a lower voltage is used, the operation maintaining time by the second power supply 15 can be lengthened.
[0029]
In this embodiment, the surge absorbing circuit 3 is constituted by the resistor 31 and the Zener diode 32, but the same effect can be obtained by using a varistor.
[0030]
The second embodiment will be described with reference to FIG.
[0031]
The second embodiment is different from the first embodiment in that the resistor 31 of the surge absorbing circuit 3 from the battery positive electrode is replaced with a diode 33.
[0032]
This can prevent the current of the second power supply 15 from flowing out to the other units 11 and 12 connected to the harness 17 when the battery is disconnected or momentary interruption, and the master unit 1 can be prevented from being discharged by the second power supply 15. operation can be maintained longer.
[0033]
The third embodiment will be described with reference to FIG.
[0034]
In the third embodiment , a voltage signal is detected by a voltage detection circuit 19 from a connection point indicated by reference numeral 18 on the battery side of the diode 33 of the second embodiment or the resistor 31 of the first embodiment. It has a means 20 for shutting off power supply to a unit (for example, 9) which does not require power supply when the potential becomes lower than a predetermined value at the time of disconnection.
[0035]
According to the present embodiment, since the current consumption of the master unit 1 can be reduced to the minimum, the operation of the master unit 1 by the second power supply 15 can be maintained for a longer time.
[0036]
In the present embodiment, the voltage is detected by the voltage detection circuit 19 and the control is performed using the means 20 for shutting off the power supply. However, the same effect can be obtained by performing the same using the microcomputer 7.
[0037]
【The invention's effect】
According to the present invention, in the control device for the internal combustion engine, even when the battery is disconnected or momentary interruption occurs, the power can be supplied from the second power supply to the master unit. On the other hand, the operation state of the system can be constantly monitored without the control device skipping over the data.
[0038]
Moreover, it can be realized with a simple circuit configuration without increasing the capacity of a high-voltage capacitor for absorbing ripple which is not frequently used.
[Brief description of the drawings]
1 is a diagram showing a first embodiment.
2 is a diagram showing a second embodiment.
3 is a diagram showing a third embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Master unit, 2 ... Battery, 3 ... Surge absorption circuit, 4 ... Voltage regulator, 7 ... Microcomputer, 8, 9 ... I / O input / output circuit, 10 ... Communication circuit, 11,
12 local unit, 15 second power supply, 16 diode, 19 voltage detection circuit, 20 means for interrupting power supply.

Claims (3)

Terminal connected to the positive electrode of the battery,
A voltage regulator connected between a power supply line extending from the terminal and ground,
On the input side of the voltage regulator, a surge absorption circuit connected in parallel with the voltage regulator,
An input-side high-withstand-voltage capacitor for ripple removal connected between the power supply line and ground on the input side of the voltage regulator;
An output-side capacitor for output voltage smoothing connected between the power supply line and ground on the output side of the voltage regulator;
A microcomputer connected between the power supply line and ground on the output side of the voltage regulator;
A communication circuit connected to the power supply line, for connecting the microcomputer and another control unit with a communication line,
A power supply circuit provided between the surge absorption circuit and the voltage regulator, having a large-capacity capacitor having a low withstand voltage different from the input-side high-withstand voltage capacitor,
With
The power supply circuit is connected in series with a resistor connected between the power supply line and ground and a zener diode connected in a forward direction as viewed from the ground, and as viewed from the ground connected between the power supply line and the ground. comprises a series connection circuit of the another capacitor and a forward biased diode Te,
A connection point between the resistor and the zener diode and a connection point between the diode and the another capacitor are electrically connected.
Control device for an internal combustion engine. In those described in claim 1, wherein the surge absorption circuit,
A control device for an internal combustion engine, comprising: a diode connected in a forward direction when viewed from the terminal side; and a Zener diode connected in a forward direction when viewed from the ground side between a cathode of the diode and ground. The voltage detection circuit according to claim 1, wherein the voltage detection circuit detects an input potential of the surge absorption circuit.
A power cutoff circuit that cuts off power supply to a part of the microcomputer when the potential becomes equal to or less than a specific value;
Control apparatus for an internal combustion engine having.

Images