JPH05139222A - Power supply for master unit of multiple harness system - Google Patents

Abstract

PURPOSE:To prevent any skipped reading of I/O) loads of a master unit and a local unit for automotive multiple harness system, in the power supply of the master unit, by feeding electric power from the second power supply in the master unit if a battery to the master unit is disconnected or shut down instantaneously. CONSTITUTION:The power supply fed from a battery enters a voltage regulator 4 through a surge absorption circuit 3, and is connected to a microcomputer 7 and I/Os 8, 9. There is also provided a communication circuit 10 which carries out multiple communication with local units 11, 12. Moreover, the second power supply 15 is formed in parallel between the surge absorption circuit 3 and the voltage regulator 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power source for a master unit of an automobile multiple harness system.

[0002]

2. Description of the Related Art In recent years, in automobiles and the like, the number of electrical components has greatly increased due to the addition of high functionality, etc.
Multiple harnesses are being adopted to simplify and reduce the weight of wire harnesses. In this multi-harness system, there are a master unit with a built-in microcomputer and a local unit without a built-in microcomputer. These units are used as master units for switches, sensors, lamps, motors, etc., which are installed closest to each other. It is connected to a unit or a local unit, is connected by multiplex transmission between the units, and is output to the output terminal of the terminal unit or the master unit based on the input / output information processed by the master unit.

As a conventional example, as shown in Japanese Utility Model Publication No. 3-32443, there is a system power supply which can reduce the power consumption of a battery as much as possible and stop the power supply to the system at an abnormal voltage. Be done.

However, as a problem in operating a multiple harness system of an automobile, when the battery is usually exhausted or the power supply is interrupted, the function of the master unit is stopped before the whole system goes down. If the power is restored again, there is a possibility that the data etc. of an object moving due to mechanical inertia will be missed while the master unit is stopped.

[0005]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to supply power to at least a communication circuit which controls multiplex communication of a microcomputer of a master unit and other local units when a battery is removed or a momentary interruption occurs. It is necessary to continue to monitor the status of the master unit and local unit.

Further, depending on the power supply capability, the power supply to the necessary parts of the master unit can be increased by stopping the flow to the other and at the same time cutting off the power supply to a part of the master unit. is there.

[0007]

As a first means, there is a method of inserting a large-capacity capacitor surge absorbing circuit, which supplies power only when the battery is disconnected or momentary interruption, between the voltage regulators.

As the second means, in addition to the first means,
There is a method of inserting a diode in the forward direction between the battery positive terminal and the surge absorption circuit.

As a third means, in addition to the second means, a signal for voltage detection is taken from the positive electrode side terminal of the battery and the anode side of the diode, and a power source for a part of the master unit is supplied according to the signal. It is a method of cutting supply.

[0010]

The function of the first means is to supply power to the master unit from the large-capacity capacitor when the battery is disconnected or momentary disconnection occurs, and the I / O load to the master unit or the local unit is eliminated due to the battery displacement or instantaneous interruption. The master unit continues to function until it is stopped electrically or mechanically, thus preventing data skipping.

Further, normally, by not supplying power, the withstand voltage of the capacitor can be suppressed to a low level, and a larger capacity capacitor can be used.

The function of the second means is to prevent the current from flowing out to another unit which receives the power supply from the battery with the common harness at the time of battery disconnection or momentary interruption, and for a longer time. Power can be supplied to the master unit by the capacitor of the first means.

The operation of the third means is that by stopping the supply of power to unnecessary portions in the master unit, it is possible to supply power to the master unit by the capacitor of the first means for a longer time. Become.

[0014]

EXAMPLE A first example will be described with reference to FIG.

The master unit 1 is supplied with power from the positive electrode of the battery 2, and is connected to a resistor and a surge absorbing circuit of a Zener diode. The Zener diode used in the surge absorbing circuit is usually 24 V or more, and has a function of absorbing a surge when an abnormal voltage such as a load dump surge is applied. A voltage regulator is connected next to the surge absorbing circuit, the capacitor 5 in the input section is for removing the power supply ripple, and a withstand voltage higher than that of the surge absorbing Zener diode is used. The capacitor 6 connected to the output of the voltage regulator is also for smoothing the output voltage, and is normally output by about 5V due to the system power supply in the unit. In the master unit 1, a microcomputer and I /
O8 and 9 are connected. A communication circuit 10 for multiplex communication with other local units 11 and 12 is connected to the microcomputer, and transmission / reception of data with the local unit is controlled by the microcomputer. The local units 11 and 12 also have communication circuits 13 and 14, which transmit the input signal of each local unit in response to a signal from the master unit.
Output to the load according to the output from the master unit. The nearest input / output load is connected to the master unit and local unit.

Here, the second power source 15 is inserted in parallel between the surge absorbing circuit 3 and the voltage regulator.

The circuit is composed of a resistor 15a for charging the large capacity capacitor 15C, a simple power source composed of a Zener diode 15b, and a diode 15d for supplying power when the battery is disconnected or momentary interruption occurs.

If the space is large, the capacity of the voltage regulator input capacitor 5 can be increased by the high withstand voltage (35 V), but it is not necessary during normal operation. 15c is provided. As a result, it is possible to use a capacitor having a low breakdown voltage (for example, 16 V) and a larger capacity. However, when the voltage regulator 4 that operates to a lower voltage is used, the operation maintaining time by the second power supply can be lengthened.

In the present invention, the surge absorbing circuit 3 is composed of a resistor and a Zener diode, but the same effect can be obtained by using a varistor.

The second embodiment will be described with reference to FIG.

The second embodiment differs from the first embodiment in that the resistance of the surge absorbing circuit diagram from the positive electrode of the battery is a diode 4.

This makes it possible to prevent the current from flowing out of the battery positive electrode 2 to the other unit connected to the harness 17 when the battery is removed or when there is a momentary interruption, and the operation of the master unit can be maintained longer by the second power source. ..

A third embodiment will be described with reference to FIG.

In the third embodiment, the voltage signal from the battery side of the diode of the second embodiment or the resistor of the first embodiment is detected by the voltage detection circuit 19, and a unit (power supply is not required at the time of battery disconnection or momentary interruption) ( For example, it has means 20 for cutting off the power supply to 9).

According to this embodiment, the current consumption of the master unit can be reduced to the minimum, so that the operation of the master unit by the second power source can be maintained for a longer time.

In the present embodiment, the voltage detection circuit 19 controls the voltage by using the means 20 for detecting the voltage and cutting off the power supply. However, the same effect can be obtained even if the same operation is performed by using the microcomputer 7. ..

[0027]

The effect of the present invention is that, in the multiple harness system for automobiles, even if the battery is removed or the battery is momentarily disconnected, the master unit can be supplied with power by using the second power source. With respect to the electrical and mechanical inertial operation of the I / O load, the operating state of the system can be monitored without skipping data reading.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment.

FIG. 2 is a diagram showing a second embodiment.

FIG. 3 is a diagram showing a third embodiment.

[Explanation of symbols]

1 ... Master unit, 2 ... Battery, 3 ... Surge absorbing circuit, 4 ... Voltage regulator, 7 ... Microcomputer, 8, 9 ... I / O input / output, 10 ... Communication circuit, 1
1, 12 ... Local unit, 15 ... Second power supply, 16
... Diode, 19 ... Battery voltage detection circuit, 20 ... Means for cutting off power supply.

Claims (3)

[Claims] 1. A component for generating a master unit power supply by a voltage regulator via a surge absorption circuit, a microcomputer to which the unit power supply is supplied, an I / O circuit thereof, and a master unit for a terminal for inputting a positive electrode of a battery. In a master unit power supply of a multi-harness system consisting of a communication circuit that transmits a serial signal to a local unit connected by multiplex communication, when the battery voltage between a surge absorption circuit and a voltage regulator of the master unit falls below a certain value. A power supply for a master unit of a multi-harness system, which has a second power supply capable of supplying power only for a certain period of time. 2. The power supply for a master unit of a multi-harness system according to claim 1, wherein the battery positive input terminal and the surge absorbing circuit are connected by a diode in the forward direction when viewed from the battery positive electrode. 3. The voltage detection circuit according to claim 2, wherein a signal is taken out from the anode side of the diode connected in the forward direction to a voltage detection circuit, and when the voltage becomes a certain value or less, a part of I / O load of the circuit in the master unit is applied. Power supply for the master unit of the multiple harness system, which is characterized by shutting off the power supply.