JPH09151781A - Power supply control device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently perform supply of power in the case that an on-vehicle battery is formed in a multipower source. SOLUTION: A battery 10 is constituted of the first power source 11 supplying power mainly to a large power load of starter 5 or the like and the second power source 12 supplying power mainly to a small power load of ECU20 or the like. A normal-close battery control relay 18 is provided between output terminals of the first/second power sources 11, 12 of the battery 10. When a starter switch 8 is turned on, the battery control relay 18 is turned off (open), and also supply of power relating to the starter 5 is started after the relay 18 is placed completely in an off-condition. Thereafter, when the starter switch 8 is turned off, the battery control relay 18 is turned on (close). In a constitution thus provided, when the starter is driven, without supplying power of the second power source 12 to the starter, stable action of the engine control ECU20 or the like is ensured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle power supply control device.

[0002]

2. Description of the Related Art Electric equipment for vehicles is designed to be operated by power supply from an on-vehicle battery. For example, a large amount of electric power is consumed when a starter is driven when the engine is started, which causes a voltage drop of the on-vehicle battery. As a countermeasure against this voltage drop, an expensive electronic device (ECU or the like) or an electric device such as an injector, whose operation is guaranteed even at a low voltage, is generally used, and even when the battery voltage drops or fluctuates, the electric device is operated. I was trying to prevent malfunction. However, according to the above measures, cost increase cannot be avoided, and in particular, due to the large number of electronic devices mounted in recent years,
The problem of cost increase has always been pointed out. On the other hand, in the "in-vehicle multi-power source battery" disclosed in JP-A-57-197751, a starter and a desired electric device (EC
U) and U) are proposed to be supplied with power from separate power sources.

[0003]

When the battery has multiple power sources as described above, the problem is how efficiently the battery can supply power to various electric devices, that is, how to utilize the full battery capacity. However, the specific structure is not disclosed in the above-mentioned conventional publication, and a technique capable of efficiently supplying electric power in such a multiple power source structure of a battery has been desired.

The present invention has been made in view of the above problems, and an object thereof is to control the power supply of a vehicle capable of efficiently supplying electric power when the on-vehicle battery has multiple power supplies. To provide a device.

[0005]

In the power supply control device for a vehicle according to the present invention, a first power supply for supplying power to a large power load such as a starter and a small power load such as an electronic device. It is assumed that a vehicle-mounted battery including a second power source for supplying electric power to the vehicle is provided.

According to the first aspect of the invention, at least the flow of current from the second power source to the first power source is blocked between the output terminal of the first power source and the output terminal of the second power source. A means for preventing energization is provided. With this configuration, for example, when the starter is driven when the engine is started (when a large electric power load is driven), the drive power is supplied to the starter by the first power source, but the energization blocking means transfers the power from the second power source to the first power source. Is blocked, so
The power of the second power supply is not supplied to the starter. Therefore, stable operation of the electronic device or the like that operates according to the power supply from the second power supply is ensured, and in turn, the power supply in the on-vehicle battery having multiple power supplies can be efficiently performed.

According to a second aspect of the invention, in the first aspect of the invention, the energization blocking means opens and closes between the output terminal of the first power source and the output terminal of the second power source. Consists of. Then, the determination means determines whether or not there is a drive command for a large power load such as a starter. When it is determined that there is a drive command for the large power load, the power supply control means opens the opening / closing switch and starts the power supply to the large power load after the opening operation of the switch, and thereafter, the power by the large power load. After the consumption is completed, the open / close switch is closed.

In this case, for example, when the starter is driven, the conduction between the first power source and the second power source is cut off by the opening operation of the open / close switch. As a result, as in claim 1, the second
Since the power of the power supply is not supplied to the starter, the stability of the voltage supplied to the electronic device or the like is ensured and the stable operation of the device or the like is guaranteed. In particular, according to the configuration of the present claim, the opening / closing switch is opened in response to the drive command to the starter or the like, and the power supply to the starter or the like is started (permitted) after the opening operation is completed. A more reliable operation can be realized. Further, according to the configuration of the present invention, the open / close switch is closed except when the starter or the like is driven. Therefore, the RAM data in the memory can be backed up by both the first and second power supplies, and The electronic device can always be operated with high accuracy.

Further, in the invention according to claim 2,
As described in claim 3, the determination means may be configured to determine the presence / absence of a drive command for the starter as a large power load depending on whether or not the starter switch is on. Further, as described in claim 4, the power supply control means is configured to open / close the switch when the voltage value of the first power supply is restored to a predetermined voltage due to reduction of power consumption or battery charging accompanying engine operation. It may be configured to close the switch.

According to a fifth aspect of the invention, in the first aspect of the invention, the energization blocking means is connected in a forward direction from the output terminal of the first power source to the output terminal of the second power source. It is configured to consist of a diode.
In this case, the diode blocks the power supply from the second power supply to the first power supply, and the operation accuracy of the electronic device or the like can be reliably ensured even when a large power load such as a starter is driven.

Further, in the invention described in claim 6, in the invention described in any one of claims 1 to 4, a shared charging device for charging the first and second power sources of the battery in accordance with the operation of the vehicle engine. The first power source and the charging device are always connected, and the second power source and the charging device are connected via the energization blocking means. In this case, the battery (first power source and second power source) can be charged by the shared charging device during the self-sustained operation after the start of the vehicle engine. That is, even when the battery has multiple power sources, a multi-system charging device is not required, which contributes to cost reduction.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. The vehicle control system in the present embodiment is an electronic control unit (hereinafter, referred to as E
CU), and the ECU is
It operates by power supply from an on-vehicle battery or power supply from an alternator as a charging device. Also,
The vehicle-mounted battery according to the present embodiment has a multi-power source structure, and supplies power to a first power source mainly for supplying power to a large power load such as a starter and mainly to a small power load such as an ECU and other electric circuits. And a second power supply for supplying. Hereinafter, a vehicle control system equipped with a battery having the above-described multi-power source structure will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an outline of a vehicle control system according to this embodiment. In FIG. 1, an engine 1 is a spark ignition type gasoline injection engine, and a crankshaft 2 of the engine 1 is connected to a flywheel 3. A ring gear 4 is provided on the outer circumference of the flywheel 3, and a pinion gear 6 of a starter 5 is engaged with the ring gear 4 so as to be able to move forward and backward. The starter 5 is driven according to the ON operation of the starter switch 8 by the driver, and the drive of the starter 5 provides the initial rotation (about 200 to 300 rpm) necessary for starting the engine 1.

Here, the starter switch 8 is turned on / off when a driver operates an ignition key (not shown).
It is turned off and is actually E for engine control.
The key switch 7 for supplying electric power to various electric devices such as the CU 20 is turned on and off. That is, when the ignition key is operated, first, the key switch 7 is turned on, and when the ignition key is further operated while the key switch is on, the starter switch 8 is turned on. When the starter switch 7 is turned on, the ON signal is input to the engine control ECU 20, and the ECU 20 determines that the starter switch = ON.

The battery 10 has a multi-power source structure including the first power source 11 and the second power source 12 as described above, and the ratio of the capacities of the first and second power sources 11 and 12 is, for example, about 8: It is configured to be 2. That is, the first power supply 11 is mainly for supplying electric power to the starter 5 and other large electric power loads 9, and naturally a large capacity is required. Examples of components corresponding to the large power load 9 include a power seat actuator, a power window actuator, and a lamp. A starter relay 13, which is a normally open electromagnetic relay, is connected between the first power source 11 and the starter 5. That is, the starter relay 13
Then, in the non-excited state of the relay coil 13a, the relay contact 1
3b is held in the open position, and the relay contact 13b is shifted to the closed position while the relay coil 13a is excited. The opening / closing operation of the starter relay 13 is controlled by the engine control ECU 20 described later.

On the other hand, the second power source 12 of the battery 10 is mainly for supplying electric power to the engine control ECU 20, the small electric power load 14, the injector 15, the igniter 16, etc., and has a relatively small capacity. To be done. Air-conditioner control E is equivalent to the small electric power load 14.
Examples include a CU, a meter control ECU, an inter-ECU communication device, and the like.

The second power source 12 is electrically connected to the engine control ECU 20, the small load power 14 and the like via the key switch 7 and the main relay 17. Main relay 1
Reference numeral 7 is a normally open electromagnetic relay, and the relay 17 is turned “on” (closed) when the key switch 7 is turned on. That is, when the key switch 7 is turned off, the relay coil 17a is not excited and the relay contact 17b is held in the open position. When the key switch 7 is turned on, the relay coil 17a is excited and the relay contact 17b is shifted to the closed position. As the main relay 17 is closed, electric power is supplied to the engine control ECU 20 and other small electric power loads 14.

A battery control relay 18, which is a normally closed electromagnetic relay, is connected between the output terminal of the first power supply 11 and the output terminal of the second power supply 12 of the battery 10. That is, in the battery control relay 18, the relay setting 18b is held in the closed position when the relay coil 18a is not excited, and the relay coil 18a
The relay contact 18b is shifted to the open position in the excited state. The opening / closing operation of the battery control relay 18 is controlled by the engine control ECU 20.

The engine control ECU 20 is mainly composed of a well-known microcomputer, and a CPU 21, which controls its operation, receives a predetermined constant voltage Vcc (= 5V) generated by a constant voltage circuit 22. It is being supplied. That is, the constant voltage circuit 22 functions as a CPU power supply, and the power supply voltage VB2 of the second power supply 12 is used.
(About 14V) is converted into a constant voltage Vcc. The constant voltage circuit 22 also serves as a backup power source for backing up the RAM data in the engine control ECU 20, and the reference numeral 23 in the drawing denotes a backup power supply from the battery 10 to the engine control ECU 20. The backup power supply line for is shown. Engine control ECU
Various detection data indicating an engine operating state is input to a sensor group 20 (not shown), and the ECU 20 controls the fuel injection amount by the injector 15 and the ignition timing control by the igniter 16 based on the detection data.

Further, the engine control ECU 20 is provided with a first transistor Tr1 for controlling the opening / closing of the battery control relay 18 and a second transistor Tr2 for controlling the opening / closing of the starter relay 13. , These transistors Tr1 and Tr2 are CPU21
ON / OFF according to the output signal of the. More specifically, when the first transistor Tr1 is turned on, the battery control relay 18 is opened (OFF), whereby the first transistor Tr1 is turned on.
The power supply 11 and the second power supply 12 are cut off. When the second transistor Tr2 is turned on, the starter relay 13
Is closed (ON), whereby power is supplied from the first power supply 11 to the starter 5. In the present embodiment, the CPU 21 constitutes the judging means and the power supply controlling means.

The alternator 25 serves to charge the battery 10 and supply electric power to various electric devices during normal traveling of the vehicle. The rotating shaft 26 of the alternator 25 is a belt 27 on the crankshaft 2 of the engine 1. Driven through. The general configuration of the alternator 25 will be briefly described below with reference to FIG. In FIG. 2, an alternator 25 is a stator coil 29 that generates a three-phase AC that is 120 ° out of phase with a rotor coil 28 that is rotated as the engine 1 is operated.
A rectifying diode 30 for converting the three-phase alternating current generated in the stator coil 29 into a direct current; and an IC regulator 31 for adjusting the voltage generated by the alternator 25.
And The IC regulator 31 includes a battery voltage control circuit 32 for controlling the battery voltage to a desired regulated voltage (for example, 14.5 V), a transistor Tr3 that is turned on / off by the control circuit 32, and a counter electromotive force absorbing device. And a diode DI.

The operation of the alternator 25 will be briefly described. For example, when the rotation of the alternator 25 increases at the time of starting the engine, the IC regulator 31 becomes P
The transistor Tr3 is continuously turned on while detecting the terminal voltage.
N operation. As a result, the power generation voltage of the alternator 25 rises rapidly, the voltage at the B terminal exceeds the battery voltage, and the charging current flows through the battery 10. And
When the ON state of the transistor Tr3 is continued, the voltage of the B terminal rises. After that, when the voltage of the S terminal exceeds the adjustment voltage (for example, 14 V), the battery voltage control circuit 32 detects this and turns off the transistor Tr3. As a result, the exciting current of the rotor coil 28 is attenuated via the counter electromotive force absorbing diode DI, and the B terminal voltage is also reduced.

When the voltage at the S terminal becomes lower than the adjustment voltage, the battery voltage control circuit 32 detects this,
The transistor Tr3 is turned on again. As a result, the exciting current of the rotor coil 28 increases and the B terminal voltage also increases. After that, the transistor Tr3 repeats the ON / OFF operation, so that the voltage of the S terminal (battery voltage) is controlled to a constant value (adjusted voltage).

Next, the operation of the vehicle control system configured as described above will be described. FIG. 3 is a time chart illustrating the control operation in the present control system, and the figure particularly shows the operation contents when the engine is started. The operation at each time in the figure will be described below in order.

When the key switch 7 is operated to the ON position at time t1, the main relay 17 is turned on accordingly.
The state becomes the N state. As a result, the engine control EC is transferred from the battery 10 via the key switch 7 and the main relay 17.
Electric power supply to the U20, the small electric power load 14 and the like is started, and the ECU 20 and the like are brought into an operating state.

At time t2, the starter switch 8 turns off.
When operated N, the engine control ECU 20 detects the ON signal of the starter switch 8, and as a result, the battery control relay 18 is switched from ON to OFF. That is, the CPU 21 in the engine control ECU 20 turns on the first transistor Tr1, whereby the relay coil 18a of the battery control relay 18 is excited and the relay contact 18b operates in the open position.

After that, the battery control relay 18 is turned on.
The starter relay 13 is switched from OFF to ON after the elapse of a predetermined time T required to shift from the (open) state to the complete OFF (closed) state. That is, the CPU 21 in the engine control ECU 20 turns on the second transistor Tr2, whereby the relay coil 13a of the starter relay 13 is excited and the relay contact 13b operates in the closed position. As a result, electric power is supplied from the first power source 11 to the starter 5 via the starter relay 13, and the starter 5 starts driving. Then, the starter 5 is driven to give the engine 1 initial rotation.

During the cranking period in which the starter 5 is driven (the ON period of the starter relay 13), the first power source 11
Since the starter 5 is supplied with electric power, the voltage VB1 of the first power supply 11 is significantly lower than the rated voltage (12V). On the other hand, since the battery control relay 18 is turned off and the connection between the second power source 12 and the starter 5 is cut off, the voltage VB2 of the second power source 12 is maintained at the rated voltage (12V). In addition, near the end of the cranking period, in addition to reducing the power consumption of the starter 5, the alternator 2 due to the increase in the engine speed is also added.
5, the charging of the first power supply 11 is started, and the first power supply 11
The voltage VB1 of is gradually increased.

When the starter switch 8 is turned off at time t3, the starter relay 13 is immediately turned off accordingly.
F will be done. That is, the CPU 21 uses the second transistor Tr2
Is turned off. Then, the starter 5 that has been the load of the engine 1 is disconnected, so that the engine speed reaches a predetermined speed or more (for example, 500 rpm), and the voltage VB2 of the second power supply 12 is a predetermined voltage (for example, 1
The battery control relay 18 is switched from OFF to ON at time t4 when the battery control relay 18 is charged to 1 V or more. That is, the CPU 21 turns off the first transistor Tr1.
F. After that, the engine speed is maintained at a predetermined idle speed (about 700 rpm), and the first power source 1
The voltages of the first and second power supplies 12 are controlled by the alternator 25 to a predetermined regulated voltage (14V).

According to the above operation, the voltage VB1 of the first power source 11 decreases with the starter driving, while the voltage VB2 of the second power source 12 hardly decreases, and the voltage VB2 from the second power source 12 does not decrease. Engine control ECU by power supply
20 and other small power loads 14 operate while maintaining good condition.

FIGS. 4 and 5 are flow charts showing a power supply control process for realizing the above-mentioned operation, in which FIG. 4 shows a battery relay control routine and FIG. 5 shows a starter relay control routine. These routines are executed by the CPU 21 in the engine control ECU 20 at predetermined time intervals. Hereinafter, regarding the routines of FIGS. 4 and 5,
An explanation will be given with reference to the time chart of FIG. 3 described above.

Now, when the routine of FIG. 4 starts,
First, in step 101, the CPU 21 determines whether or not the starter switch 8 is off. For example, when the starter switch 8 is turned on when the engine is started (Fig. 3
Time t2-), step 101 is negatively determined, CP
U21 turns on the first transistor Tr1 to turn off (open) the battery control relay 18 in step 105.
Let it. By turning off this battery control relay 18,
The electrical connection between the first power supply 11 and the second power supply 12 of the battery 10 is cut off.

In step 102, the CPU 21 determines whether the engine speed Ne is equal to or higher than a predetermined speed, and in step 103, the voltage VB1 of the first power source 11 is higher than a sufficiently high voltage (for example, 11 V). It is determined whether or not there is. If either of steps 102 and 103 is not established, the CPU 21 proceeds to step 105 and holds the battery control relay 18 in the OFF (open) state.

If both steps 102 and 103 are established, the CPU 21 proceeds to step 104 and turns on (closes) the battery control relay 18 by the first transistor T.
Drive r1 OFF. That is, in FIG. 3, all the conditions of steps 101 to 103 are satisfied at time t4, and the battery control relay 18 is turned on. As a result, the alternator 25 is applied to the second power supply 12 in addition to the first power supply 11 up to then.
Charging current is supplied from.

On the other hand, when the routine of FIG. 5 starts,
First, in step 201, the CPU 21 determines whether or not the starter switch 8 is ON. For example, when the starter switch 8 is turned on when the engine is started (time t2 in FIG. 3), the affirmative decision is made in step 201, and the CPU
21, the battery control relay 18 is turned off in step 202.
It is determined whether or not it is in the FF (open) state. At this time,
According to the routine of FIG. 4, the battery control relay 18 turns off.
If the FF has been performed, the CPU 21 proceeds to step 203 and determines whether or not a predetermined time T has passed since the battery control relay 18 was turned off. And step 20
When both 2 and 203 are affirmatively determined, the CPU 21 turns on the starter relay 13 in step 204. That is, the second transistor Tr2 is turned on. By the processing of steps 201 to 204, the first power supply 11 and the second power supply 11
The battery control relay 18 between the power sources 12 is surely turned off.
After being (opened), the power supply from the second power source 12 to the starter 5 is started.

On the other hand, when the starter switch 8 is turned off (time t3 in FIG. 3), a negative determination is made in step 201, and the CPU 21 determines in step 205 the starter relay 1
Turn 3 off (open). That is, the second transistor T
Turn off r2.

The effects of this embodiment will be described below. (A) In the present embodiment, the first power source 11 of the battery 10
A normally-closed battery control relay 18 is provided between the output terminal of the battery and the output terminal of the second power supply 12. Then, when the starter switch 8 is turned on, the battery control relay 18 is turned on.
FF (open) (step 105 in FIG. 4),
After the relay 18 is turned off, power supply to the starter 5 is started (step 204 in FIG. 5), and then the battery control relay 18 is turned on when the starter switch 8 is turned off.
N (closed) (step 10 in FIG. 4)
4).

According to this structure, the stable operation of the engine control ECU 20 and the like is guaranteed without supplying the electric power of the second power source 12 to the starter 5 when the starter is driven. Particularly, in the present embodiment, the battery control relay 18
Wait for the required time T during ON-OFF operation of the starter 5
Since it is driven, even more reliable operation can be realized. As a result, it is possible to efficiently supply power when using the battery 10 having multiple power sources.

(B) The battery control relay 18 is in the ON (closed) state except when the starter 5 is driven. Therefore, both power sources 11 and 12 in the battery 10 can back up the memory or the like, and the electronic device such as the ECU can always be operated with high accuracy. Since the normally closed battery control relay 18 is used,
Even when the ECU is stopped, it is possible to back up with both power supplies 11 and 12.

(C) When the voltage VB1 of the first power supply 11 returns to a predetermined voltage, the battery control relay 18 is turned off.
Since the relay is switched from ON to ON, the voltage VB2 of the second power supply 12 is not lowered when the first power supply 11 and the second power supply 12 are connected due to the relay switching.

(D) In the present embodiment, the first power source 11 of the battery 10 and the alternator 25 are always connected, and the second power source 12 of the battery 10 and the alternator 25 are connected via the battery control relay 18. . In this case, the battery 10 (the first power supply 11 and the second power supply 12) can be charged by the common alternator 25 when the vehicle engine is operating. That is, even when the battery has multiple power sources, a multi-system charging device is not required, which contributes to cost reduction.

(E) In this embodiment, the driver mistakenly turns on the starter key 8 while the engine is operating, and the starter 5 is turned on.
When the battery is driven, the battery control relay 18
Can be turned off, and the voltage drop of the second power supply 12 in such a case can be prevented in advance.

(F) In the present embodiment, the capacity ratio between the first power supply 11 requiring large power and the second power supply 12 requiring small power is set according to each power consumption (in the present embodiment, , 8: 2). That is, when the battery 10 has multiple power sources, each power source has the required minimum capacity, and therefore the battery as a whole does not increase in size.

(Second Embodiment) Next, a second embodiment of the present invention will be described. However, in the configuration and the like of the present embodiment, the description of the common parts with the first embodiment will be omitted, and the differences will be mainly described. That is, in the first embodiment, the battery control relay 18 is composed of a normally closed (normally closed) electromagnetic relay, whereas in the present embodiment, the battery control relay 18 is normally open (normally closed). It has been changed to an open type) electromagnetic relay.

More specifically, in the configuration of FIG. 1, the battery control relay 18 is replaced with a normally open electromagnetic relay. In this case, when the first transistor Tr1 is OFF (when the relay coil 18a is not excited), the battery control relay 18 is turned OFF (opened) and the first power source 11 and the second power source 12 of the battery 10 are connected. The electrical connection is maintained in the disconnected state. In addition, the first transistor Tr1 is O
If N (when the relay coil 18a is excited), the battery control relay 18 is turned on (closed) and the first power supply 11
And the second power supply 12 are electrically connected.

The control operation of the vehicle control system according to the present embodiment will be described below with reference to the time chart of FIG. Now, when the key switch 7 is operated to the ON position at time t11, the main relay 17 is accordingly turned on, and the engine control ECU 20 and the like are activated. Further, when the starter switch 8 is turned on at time t12, the starter relay 13 is accordingly switched from off to on. At this time, in the case of the first embodiment described above, the starter relay 13 was turned on after the battery control relay 18 was reliably turned off. However, in the case of the present embodiment, the battery control relay 18 is turned on.
Is always OFF, so OF of the battery control relay 18
There is no need to wait for the F operating time.

Then, at time t13, the starter switch 8 is turned on.
When is turned off, the starter relay 13 is turned off immediately
Is done. Further, at the time t14 when the engine speed reaches the predetermined speed or more (for example, 500 rpm) and the voltage VB2 of the second power supply 12 is charged to the predetermined voltage (for example, 11 V) or more, the battery control relay 18 is operated.
Is switched from OFF to ON. After that, the engine speed is maintained at a predetermined idle speed (about 700 rpm), and the voltages of the first power supply 11 and the second power supply 12 are controlled by the alternator 25 to a predetermined adjustment voltage (14V). As described above, when the starter is driven when the engine is started, the voltage VB1 of the first power supply 11 largely changes, while the voltage VB2 of the second power supply 12 hardly decreases and stable power supply is possible.

Then, the CPU 21 executes the battery relay control routine shown in FIG. 7 in order to obtain the above operation.
Here, in the routine of FIG. 7, the battery control relay 18
ON / OF of the first transistor Tr1 for opening and closing
Only the F operation (steps 304 and 305) is the ON / OFF operation of the routine of FIG. 4 (steps 104 and 105).
Others are the same as those in FIG. Further, as the starter relay control routine, the routine of FIG. 5 is adopted as it is. However, since the normally open type battery control relay 18 is used in the present embodiment, the battery control relay 18 is switched from ON to OF when the starter is driven when the engine is started.
It is not necessary to wait for the elapse of the required time T until switching to F, and step 203 in FIG. 5 can be omitted (necessary when switching the relay 18 from ON to OFF during engine operation).

As described above, according to the present embodiment, the stable operation of the engine control ECU 20 and the like by the power supply from the second power supply 12 is ensured, and the battery 10 having multiple power supplies is provided as in the first embodiment. When used, power can be efficiently supplied.

(Third Embodiment) Next, a third embodiment of the present invention will be described. However, in the configuration and the like of the present embodiment, description of common parts with the first and second embodiments will be omitted, and differences will be mainly described.

FIG. 8 is a diagram showing the configuration of the vehicle control system in the present embodiment. In the figure, an inter-power diode 35 as an energization blocking means is provided between the output terminal of the first power supply 11 and the output terminal of the second power supply 12 of the battery 10. The diode 35 is connected in the forward direction from the output terminal of the first power supply 11 to the output terminal of the second power supply 12. In this case, electric power is not supplied from the second power supply 12 to the starter 5 and the like when the starter 5 and the large power load 9 are driven, and the voltage of the second power supply 12 is maintained at a predetermined value. When the engine is operating, the charging current from the alternator 25 is supplied to the second power supply 12, the engine control ECU 20, etc. via the inter-power supply diode 35. The voltage of the first power supply 11 and the voltage of the second power supply 12 differ by the amount of the drop of the diode 35 between the power supplies (about 0.7 V), but the voltage of the second power supply 12 is taken in by the alternator 25 and is adjusted to the adjustment voltage. The charging operation is performed by the difference.

As described above, according to this embodiment, the following effects can be obtained. (A) Since the diode 35 between the power supplies blocks the energization from the second power supply 11 to the first power supply 11, stable operation of the engine control ECU 20 and the like can be ensured when the starter is driven. The electric power can be efficiently supplied.

(B) Engine control EC from the first power supply 11
Since electric power can be supplied to the U20 and the like at all times, it is possible to reliably back up the memory and the like. (C) Since the object of the present invention can be realized only by the hardware configuration, the control from the engine control ECU 20 becomes unnecessary.

(D) It is not necessary to provide a plurality of alternators for each power source, and the common alternator can be used to charge the battery and supply power to various electric devices during engine operation. As a result, cost reduction can be realized.

The present invention can be embodied in the following modes in addition to the above embodiments. (1) In the first and second embodiments, when the starter signal is input, the battery control relay 18 is turned off,
Although the connection between the first power source 11 and the engine control ECU 20 and the like is cut off, the battery control relay 18 may be switched to the OFF state when the drive command signal is input by the large power load 9. More specifically, for example, when the power seat switch is turned on,
The ECU detects this and turns off the battery control relay 18.
F. Then, after the battery control relay 18 is surely turned off, power supply from the first power source 11 to the power seat actuator (large power load 9) is permitted,
The actuator is driven. After that, when the power seat switch is turned off, the battery control relay 18 is turned back on. The same process is performed when driving a power window actuator, a lamp, or the like as the large power load 9.

According to the above construction, the power source voltage of various ECUs does not drastically drop when the vehicle is operated in any state, and various control operations can be maintained as normal. As a result, it is possible to continue favorable vehicle running even if the power consumption increases due to the driving of the large power load.

(2) In the embodiment shown in FIG. 1, the battery control relay 18 and the starter relay 13 are independent relays, and each relay is an engine control EC.
Although the configuration is controlled by U20, this may be changed as shown in FIG. That is, in FIG. 9, the three-terminal relay 40 is provided between the first power source 11 and the second power source 12 as an energization blocking means. In this case, if the driver turns on the starter switch 8, the connection between the first power supply 11 and the second power supply 12 is cut off, and the first power supply 11 and the starter 5 are connected. When the starter switch 8 is turned off, the connection between the first power supply 11 and the starter 5 is cut off, and the first power supply 11 and the second power supply 12 are connected.

Further, as the three-terminal relay 40, the first
A relay (for example, a relay with an orifice) having a mechanism for delaying the time from the disconnection of the connection between the power supply 11 and the starter 5 to the connection between the first power supply 11 and the second power supply 12 by a predetermined time or more is used. You may. In this case, the first
When the voltage of power supply 11 has returned to a sufficient value, both power supplies 1
1, 12 will be connected.

(3) In the above embodiment, the first power source 11 and the second power source 12 are formed in one battery 10. However, it is also possible to form both of these power sources as separate batteries.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an outline of a vehicle control system according to a first embodiment.

FIG. 2 is a circuit diagram showing an electrical configuration of an alternator.

FIG. 3 is a time chart for explaining the operation of the first embodiment.

FIG. 4 is a flowchart showing a battery relay control routine.

FIG. 5 is a flowchart showing a starter relay control routine.

FIG. 6 is a time chart for explaining the operation of the second embodiment.

FIG. 7 is a flowchart showing a battery relay control routine according to the second embodiment.

FIG. 8 is a configuration diagram showing an outline of a vehicle control system according to a third embodiment.

FIG. 9 is a configuration diagram showing a part of a vehicle control system according to another embodiment.

[Explanation of symbols]

5 ... Starter, 9 ... Large power load, 10 ... Battery, 11
... 1st power supply, 12 ... 2nd power supply, 14 ... Small electric power load, 18
... Battery control relay as energization prevention means (open / close switch), 20 ... Engine control ECU, 21 ... Determination means,
CPU as power supply control means, 25 ... Alternator as charging device, 35 ... Diode between power supplies as current blocking means, 40 ... Three-terminal relay as current blocking means.

Claims (6)

[Claims] 1. A vehicle provided with an on-vehicle battery mainly composed of a first power supply for supplying electric power to a large electric power load such as a starter and a second power supply mainly supplying electric power to a small electric power load such as an electronic device. The power supply control device according to claim 1, wherein at least an energization blocking means for blocking a current flow from the second power supply to the first power supply between the output terminal of the first power supply and the output terminal of the second power supply. A power supply control device for a vehicle, comprising: 2. The energization preventing means comprises an open / close switch that opens and closes between an output terminal of the first power supply and an output terminal of the second power supply, and determines whether or not there is a drive command for a large power load such as the starter. When it is determined that there is a driving command for the large power load, the determination means for determining determines that the open / close switch is opened and the power supply to the large power load is started after the opening operation of the switch. The power supply control device for a vehicle according to claim 1, further comprising a power supply control unit that closes the open / close switch when power consumption ends. 3. The vehicle power supply control device according to claim 2, wherein the determination means determines whether or not there is a drive command for the starter as a large power load, depending on whether or not the starter switch is on. Vehicle power supply control device. 4. The vehicle power supply control device according to claim 2 or 3, wherein the power supply control means sets the voltage value of the first power supply to a predetermined value by reducing the amount of power consumption or charging the battery accompanying the operation of the engine. The power supply control device for a vehicle, which closes the open / close switch when the voltage returns to the above voltage. 5. The power supply control device for a vehicle according to claim 1, wherein the energization prevention means comprises a diode connected in a forward direction from an output terminal of the first power supply to an output terminal of the second power supply. 6. The power supply control device for a vehicle according to claim 1, further comprising a shared charging device that charges the first and second power supplies of the battery, the first power supply and the charging device. While always connecting and
A power supply control device for a vehicle, wherein the second power supply and the charging device are connected via the energization prevention means.