JP2006161756A - Power control unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power control unit which can prevent momentary cutoff of a relay. <P>SOLUTION: The power control unit is provided with an engine ECU50; an ignition switch 60; a power supply relay 70; and a power source 80 etc.The engine ECU50 is connected to the power source 80, being a loaded battery, through the ignition switch 60 and a power supply relay 70. Further, the engine ECU50 is provided with a power supply relay drive circuit 10; a power circuit 20; a microcomputer 30; and a delay circuit 40 etc. In the power control unit, when the ignition switch 60 is turned ON, an on-signal indicating that the ignition switch is turned ON is inputted into the microcomputer 30 and the emitter of a transistor 13 and inputted into the power supply relay drive circuit 10 after only a delay time set at the delay circuit 40 elapses. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a power supply control device.

  Conventionally, there has been an electronic control device including a power supply relay disclosed in Patent Document 1.

  The electronic control device shown in Patent Document 1 includes an ECU including a power circuit, a CPU, and the like, and a power switch, an actuator, and a power supply relay connected to the ECU.

  In this electronic control device, when the power switch is turned on, the contact of the power supply relay is turned on. And the power supply voltage from a power supply is applied to ECU via the contact of a power supply relay. That is, the power supply voltage from the power supply is applied to the CPU via the contact of the power supply relay and the power supply circuit.

When the power switch is turned off, the supply of the power supply voltage to the ECU is held until the actuator shutdown operation by the CPU is completed. Then, when the actuator shutdown operation by the CPU is completed, the power supply relay is turned off and the power supply to the ECU is stopped.
JP-A-5-18315

  However, in the power supply control device in Patent Document 1, the time from when the power supply relay is turned off to when the power switch is turned on cannot be controlled. In this case, if the power switch is turned on immediately after the power supply relay is turned off, the power supply relay may be instantaneously interrupted. Further, even when the supply of power supply voltage to the ECU is not maintained from when the power switch is turned off until the shutdown operation is completed, the power switch is switched from off to on in a short time. There was a possibility that the power supply relay could be momentarily interrupted. As described above, when the power supply relay is momentarily cut off, there is a possibility that the contact of the power supply relay is fixed.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a power supply control device that can prevent the relay contact from being stuck due to instantaneous interruption of the relay.

  In order to achieve the above object, a power supply control device according to claim 1 is a power supply control circuit for controlling power supply from a power supply to an electric load, and a signal for instructing connection between the electric load and the power supply. A power switch means for outputting; a relay means for electrically connecting the electrical load and the power source when in the on state; and a relay means for interrupting an electrical connection between the electrical load and the power source when in the off state; Relay driving means for turning on the relay means based on a signal instructing connection of the power supply, and a delay circuit for delaying the time from the output of the signal instructing connection to the power supply to turning on the relay means It is characterized by this.

  Thus, by providing a delay circuit that delays the time from the output of the signal instructing connection of the power supply to the ON state of the relay means, the connection of the power supply is instructed immediately after the relay means is turned OFF. Even when a signal is output, it is possible to secure a time until the relay means is turned on, so that an instantaneous interruption of the relay can be prevented.

  Further, in the power supply control device according to claim 2, the power switch means instructs disconnection of the connection between the electric load and the power supply. When a signal instructing connection with the power supply is output, the relay means A relay holding signal for holding the ON state is output to the relay driving means, and a cutoff control means for stopping output of the relay holding signal after a predetermined time when a signal instructing disconnection of the connection is output is provided. It is what.

  As described above, when a signal instructing connection to the power supply is output, the relay unit is kept on, and when a signal instructing disconnection is output, the relay unit is turned off after a predetermined time. Even in the case where the control means is provided, it is possible to prevent the relay contacts from being stuck due to the instantaneous interruption of the relay by electrically connecting with the electric switch means without going through the delay circuit.

  According to a third aspect of the present invention, when the signal for instructing the disconnection of the connection is output, the disconnection control means outputs a signal for instructing the connection with the power source during a predetermined time. If the signal that instructs connection to the power supply is not output, the relay holding signal output is stopped, and if the signal that instructs connection to the power supply is output, the relay holding signal is output. It is provided with the interruption | blocking control means which maintains the output of (2).

  If a signal instructing connection to the power supply is output during the period from when the signal that shuts off the power supply is output until the output of the relay holding signal is stopped, the relay holding signal is output due to the influence of the delay circuit. The relay means may be turned on immediately after stopping. That is, there is a possibility that the relay means is instantaneously turned off.

  However, as shown in claim 3, when a signal instructing disconnection of the connection is output, monitoring of the signal instructing connection with the power source is started and a signal instructing connection with the power source is output. In this case, by maintaining the output of the relay holding signal, it is possible to continue the ON state of the relay unit without setting the relay unit to the OFF state, so that instantaneous interruption of the relay unit can be reliably prevented.

  According to a fourth aspect of the present invention, when the signal for instructing connection with the power supply is output after the relay holding signal is stopped, the shutoff control means maintains the stop of the relay holding signal output. It is characterized by this.

  Even after the relay holding signal is stopped, the cutoff control means is in operation for a short time. In such a situation, if a signal instructing connection to the power supply is output, the relay holding signal that has been stopped will be output, and the relay means may be in a state of being momentarily interrupted There is. However, as described in claim 4, when a signal instructing connection of the power source is output between the time when the relay holding signal is stopped and the time when the relay means is turned off, the output of the relay holding signal is stopped. By maintaining this, the instantaneous interruption of the relay means can be surely prevented.

  Further, as shown in claim 5, the power switch means may be at least one of an ignition switch, a door opening / closing switch, and a fuel lid opening switch mounted on the vehicle. The delay circuit can be an RC delay circuit comprising a resistor and a capacitor.

  Further, the relay driving means comprises a transistor and an OR circuit connected to the base of the transistor, as shown in claim 7, the emitter terminal of the transistor being connected to the power switch, and the collector terminal being a coil of the relay means. The OR circuit can take the logical sum of the signal indicating the connection of the power source delayed by the delay circuit and the relay holding signal.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of a power supply control device according to an embodiment of the present invention. FIG. 2 is a block diagram showing a schematic configuration of the delay circuit in the embodiment of the present invention. In the present embodiment, an example in which the power supply control device of the present invention is applied to an engine control device 50 (hereinafter also referred to as an engine ECU) will be described.

  The power supply control device in the present embodiment includes an engine ECU 50, an ignition switch 60, a power supply relay 70, a power supply 80, and the like.

  The engine ECU 50 is connected to a power source 80 that is a vehicle-mounted battery via an ignition switch 60 and a power supply relay 70, and is connected to an actuator such as an injector or an igniter of an engine (not shown). The engine ECU 50 includes a power supply relay drive circuit 10, a power supply circuit 20, a microcomputer 30, a delay circuit 40, a circuit device (not shown), and the like.

  The power supply relay drive circuit 10 includes an OR circuit 11, a NOT circuit 12, a transistor 13, and the like.

  The OR circuit 11 is a 2-input OR circuit, the first input terminal (a terminal) is connected to the ignition switch 60 via the buffer and delay circuit 40, and the second input terminal (b terminal) is a microcomputer. 30. The output terminal of the OR circuit 11 is connected to the base of the transistor 13 via the NOT circuit 12. The OR circuit 11 takes a logical sum of an ignition signal input via the buffer and delay circuit 40 and indicating that the ignition switch 60 is on / off and a relay holding signal described later, and calculates the logical sum. The result is output to the base of the transistor 13 via the NOT circuit 12.

  The emitter of the transistor 13 is connected to the ignition switch 60 via the diode D1, and is connected to the relay contact 72 of the power supply relay 70 via the diode D2. The collector of the transistor 13 is connected to the relay coil 71 of the power supply relay 70.

  The power supply circuit 20 is connected to the relay contact 72 of the power supply relay 70, the microcomputer 30, other circuit devices (not shown), and the like, and is also connected to the ground. When power is supplied from the power supply 80, the power supply circuit 20 generates a predetermined constant voltage and supplies this constant voltage to the microcomputer 30 and other circuit devices.

  The microcomputer 30 includes a well-known CPU for executing a program, a nonvolatile EEPROM for storing a program executed by the CPU and data referred to when the program is executed, and a volatile memory for temporarily storing calculation results of the CPU. As a RAM. When the ignition switch 60 is turned on, the microcomputer 30 outputs a relay holding signal for holding the ON state of the power supply relay 70 (relay contact 72). When the ignition switch 60 is turned off, the microcomputer 30 performs a shutdown process such as storing data in an EEPROM or diagnosing a failure of an actuator (not shown) according to a program, and outputs a relay holding signal when the shutdown process ends. Stop.

  As shown in FIG. 2, the delay circuit 40 is an RC delay circuit including a resistor 41 and a capacitor 42. An ignition signal indicating ON / OFF of the ignition switch 60 is input to the delay circuit 40, delayed by a predetermined delay time (for example, 100 ms) determined by the RC time constant, and then supplied to the power supply relay drive circuit 10 (OR circuit 11). Entered. The delay circuit 40 is not limited to the RC delay circuit, and an ignition signal is delayed by a predetermined delay time (for example, 100 ms) and input to the power supply relay drive circuit 10 (OR circuit 11). Anything is acceptable. The delay time may be a time that does not cause an instantaneous interruption of the power supply relay 70.

  The ignition switch 60 is turned on / off when the driver operates the ignition key. The power supply relay 70 includes a relay coil 71, a relay contact 72, and the like. In addition, the power supply relay 70 may cause a problem with an instantaneous interruption.

  Here, the malfunction which arises with the momentary interruption | blocking of the power supply relay 70 is demonstrated. As will be described later, when the power supply relay 70 is turned on, the ignition switch 60 is turned on. When the power supply relay 70 is turned off, the ignition switch 60 is turned off and the microcomputer 30 holds the relay. This is done by stopping the output of the signal. Therefore, the case where the power supply relay 70 is turned on is not synchronized with the case where the power supply relay 70 is turned off. That is, the ignition 60 may be turned on immediately after the power supply relay 70 is turned off.

  In this way, if the ignition 60 is turned on immediately after the power supply relay 70 is turned off, the power supply relay 70 may be momentarily cut off, and accordingly, the engine ECU 50 is connected to the engine ECU 50. There is a possibility that the power supply is instantaneously interrupted.

  When the power supply relay 70 is interrupted instantaneously, heat is generated by the occurrence of arc discharge at the relay contact 72, and the relay contact 72 may be fixed, which is not preferable. In general, circuit devices such as various ICs generate an internal reset when power is supplied. However, when the power supply to the engine ECU 50 is momentarily interrupted as described above, the power is supplied again in a state where the power supply voltage is not sufficiently lowered, and therefore, the internal reset may not be executed normally. If the internal reset is not executed normally, the output of the circuit device does not become an expected value, and a malfunction may occur.

  Here, the operation of the power supply control device according to the present embodiment will be described with reference to the drawings. FIG. 3 is a timing chart for explaining the operation of the power supply control device according to the embodiment of the present invention.

  First, when the ignition switch 60 is turned on (time point A in FIG. 3), an ignition signal indicating that the ignition switch 60 is turned on (hereinafter also referred to as an on signal) is input to the IGSW terminal of the engine ECU 50. The ON signal is input to the emitter of the transistor 13 via the delay circuit 40 and the power supply relay drive circuit 10 (a terminal of the OR circuit 11), the c terminal of the microcomputer 30, and the diode D1. However, since the ON signal is input to the power supply relay drive circuit 10 (a terminal of the OR circuit 11) via the delay circuit 40, at the time of A in FIG. Only input to the emitter.

  When a delay time determined by the RC time constant of the delay circuit 40 elapses after the ignition switch 60 is turned on, the on signal is input to the power supply relay drive circuit 10 (a terminal of the OR circuit 11). At this time, the relay holding signal from the microcomputer 30 is not output, and the power supply relay driving circuit 10 outputs the driving circuit signal from the collector of the transistor 13 to the REL terminal.

  When this drive circuit signal is output, the relay coil 71 of the power supply relay 70 is excited, the relay contact 72 is turned on, and the power supply relay 70 is turned on. As a result, the power is supplied from the power supply 80 to the + B terminal and the power supply circuit 20 is supplied with power.

  When power is supplied from the power supply 80, the power supply circuit 20 generates a predetermined constant voltage and supplies the constant voltage to the microcomputer 30 or the like. When a constant voltage is supplied from the power supply circuit 20, the microcomputer 30 executes a program to send a relay holding signal for holding the ON state of the power supply relay 70 (relay contact 72) to the b terminal of the OR circuit 11. Output.

  Next, when the ignition switch 60 is turned off (time B in FIG. 3), an ignition signal (hereinafter also referred to as an off signal) indicating that the ignition switch 60 is off is input to the IGSW terminal of the engine ECU 50. The The off signal is input to the emitter of the transistor 13 via the delay circuit 40 and the power supply relay drive circuit 10 (a terminal of the OR circuit 11), the c terminal of the microcomputer 30, and the diode D1. However, the OFF signal is input to the power supply relay driving circuit 10 (a terminal of the OR circuit 11) via the delay circuit 40, and the emitter of the transistor 13 is connected from the + B terminal to the diode D2. Since power is supplied, it is input only to the c terminal of the microcomputer 30 at the time point B in FIG.

  When the delay time determined by the RC time constant of the delay circuit 40 elapses after the ignition switch 60 is turned off, the off signal is input to the power supply relay drive circuit 10 (a terminal of the OR circuit 11). When the off signal is input, the microcomputer 30 performs storage processing of data in the EEPROM and shutdown processing of an actuator (not shown) according to the program, and stops output of the relay holding signal when the shutdown processing ends.

  When the microcomputer 30 stops outputting the relay holding signal, the power supply relay drive circuit 10 stops outputting the drive circuit signal. Then, the relay coil 71 of the power supply relay 70 is de-energized, the relay contact 72 is turned off, and the power supply relay 70 is turned off. As a result, the power supply from the power supply 80 to the + B terminal is cut off and the power supply to the power supply circuit 20 is cut off.

  When the ignition switch 60 is turned on immediately after such a power supply relay 70 is turned off (at time C2), the on signal is output after the delay time has elapsed. a terminal). Therefore, the drive circuit signal to the REL terminal and the power supply from the power source 80 to the + B terminal are also output after the delay time has elapsed. In other words, the power supply relay 70 can be kept off for the delay time, and the instantaneous interruption of the power supply relay 70 and the supply of power to the engine ECU 50 can be prevented.

  Further, the microcomputer 30 checks the ON signal of the ignition switch 60 when the OFF signal of the ignition switch 60 is output. If the microcomputer 30 determines that the ON signal is output, the microcomputer 30 interrupts the shutdown process and maintains the output of the relay holding signal. If the microcomputer 30 determines that the ON signal is not output, the microcomputer 30 continues the shutdown process. Stop the relay holding signal output.

  For example, when the ignition switch 60 is turned on at the time point C1 indicated by the one-dot chain line in FIG. Then, the output of the relay holding signal is maintained. Therefore, the drive circuit signal to the REL terminal and the power supply from the power source 80 to the + B terminal are continued as indicated by the alternate long and short dash line.

  In addition, when the microcomputer 30 checks the ON signal of the ignition switch 60, it is preferable to perform the check immediately before stopping the output of the relay holding signal. By checking the ON signal immediately before stopping the output of the relay holding signal, it is possible to reliably detect whether the ON signal is output.

  Also, if the ON signal output is not detected in the situation where the ON signal is not checked immediately before stopping the relay holding signal output, the ON signal is output immediately after the relay holding signal output is stopped due to the delay time. There is a possibility of being input to the power supply relay drive circuit 10. In this case, there is a possibility that momentary interruption of the power supply relay 70 and momentary interruption of the power supply to the engine ECU 50 may occur.

  However, by checking the ON signal immediately before stopping the output of the relay holding signal, the ON signal is supplied from the output of the relay holding signal even if the ON signal output is not detected. A time until input to the relay drive circuit 10 can be ensured. Therefore, instantaneous interruption of the power supply relay 70 and instantaneous interruption of the power supply to the engine ECU 50 can be prevented.

  In addition, when checking the ON signal immediately before stopping the output of the relay holding signal, the time from the ON signal check timing to the stop of the relay holding signal output is sufficiently shorter than the delay time. The instantaneous interruption of the power supply relay 70 and the instantaneous interruption of the power supply to the engine ECU 50 can be effectively prevented.

  The microcomputer 30 is connected to a capacitor (not shown) or the like inside, and operates even for a short time by discharging from the capacitor after the relay holding signal is stopped. If the relay holding signal is output within a short time after the relay holding signal is stopped, there is a possibility that the power supply relay 70 is momentarily cut off. Therefore, when the ON signal of the ignition switch 60 is output within this short time, the microcomputer 30 keeps the output of the relay holding signal stopped.

  In the present embodiment, the example in which the power supply control device of the present invention is applied to the ignition switch (IGSW) of the engine ECU 80 has been described, but the present invention is not limited to this. For example, the present invention may be applied to all ECUs that need to supply power to the ECU with a switch operated by a user, such as a vehicle door switch or a fuel lid switch.

It is a block diagram which shows schematic structure of the power supply control apparatus in embodiment of this invention. It is a block diagram which shows schematic structure of the delay circuit in embodiment of this invention. It is a timing chart explaining operation | movement of the power supply control apparatus in embodiment of this invention.

Explanation of symbols

10 power supply relay drive circuit, 11 OR circuit, 12 NOT circuit, 13 transistor, 20 power supply circuit, 30 microcomputer, 40 delay circuit, 41 resistor, 42 capacitor, 50 engine control device, 60 ignition switch, 70 power supply relay, 71 Relay coil, 72 Relay contact, 80 Power supply

Claims (7)

A power supply control circuit for controlling power supply from a power supply to an electrical load,
Power switch means for outputting a signal instructing connection between the electric load and the power source;
Relay means for electrically connecting the electrical load and the power source when in an on state, and for disconnecting an electrical connection between the electrical load and the power source when in an off state;
Relay drive means for turning on the relay means based on a signal instructing connection with the power source;
A delay circuit for delaying a time from the output of a signal instructing connection with the power source to turning on the relay means;
A power supply control device comprising:   The power switch means instructs disconnection of the connection between the electric load and the power supply, and a relay for maintaining the ON state of the relay means when a signal instructing connection with the power supply is output. 2. A cutoff control means for outputting a holding signal to the relay driving means and stopping the output of the relay holding signal after a predetermined time when a signal instructing the cutoff of the connection is outputted. The power supply control device described in 1.   When the signal for instructing disconnection of the connection is output, the disconnection control means starts monitoring whether or not a signal for instructing connection with the power source is output during the predetermined time, When the signal instructing connection with the power supply is not output, the output of the relay holding signal is stopped, and when the signal instructing connection with the power supply is output, the output of the relay holding signal is maintained. The power supply control device according to claim 2, further comprising a shutoff control unit.   The shut-off control means maintains the stop of output of the relay holding signal when a signal instructing connection with the power source is output after stopping the relay holding signal. The power supply control device according to claim 3.   The power supply control device according to any one of claims 1 to 4, wherein the power switch means is at least one of an ignition switch, a door opening / closing switch, and a fuel lid opening switch mounted on a vehicle.   6. The power supply control device according to claim 1, wherein the delay circuit is an RC delay circuit.   The relay driving means includes a transistor and an OR circuit connected to the base of the transistor, the emitter terminal of the transistor is connected to a power switch, and the collector terminal is connected to the ground via the coil of the relay means. 3. The OR circuit according to claim 2, wherein the OR circuit takes a logical sum of a signal instructing connection with the power source delayed by the delay circuit and the relay holding signal. The power supply control device according to claim 6.

Images