JP2017052473A - On-vehicle power supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an on-vehicle power supply device in which power supply from a secondary battery to the outside is hardly disturbed by a failure or the like of a main battery.SOLUTION: An on-vehicle power supply device 100 includes a main battery 1, a secondary battery 2, a conductor part 31, a main feeding end 33a, a secondary feeding end 33b, and a drive circuit 32. The conductor part 31 is normally in a conduction state, and is changeable from the conduction state to a non-conduction state. The secondary battery 2 is connected to the main battery 1 through the conductor part 31. The main feeding end 33a supplies power from the main battery 1 to an important load 6. The secondary feeding end 33b supplies power from the secondary battery 2 to the important load 6. The drive circuit 32 changes the conductor part 31 from a conduction state to a non-conduction state due to voltage reduction of the main battery 1.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an on-vehicle power supply device, and more particularly to an on-vehicle power supply device including a plurality of types of batteries.

  In recent years, motorization of vehicle loads has progressed. Some loads that are electrified perform functions related to running, steering, and stopping. Therefore, loss of battery function (including its malfunction: the same shall apply hereinafter) should be avoided. Therefore, a technique for mounting a sub battery (hereinafter referred to as “sub battery”) as a backup of the power source has been proposed (see Patent Document 1 below).

  In Patent Document 1, power is supplied from a main battery (hereinafter referred to as “main battery”) and a sub battery to an important load (hereinafter referred to as “important load”) to be backed up.

JP2015-83404A

  In Patent Document 1, if the charging rate of the sub battery is outside the proper range, the sub battery is shut off from the power feeding path using a switch. However, when the switch is not cut off, the main battery and the sub battery are connected via an important load.

  Therefore, when a ground fault occurs on the main battery side and the control device that controls the switch fails, there is a concern that the secondary battery may not be able to secure power supply to the important load due to the ground fault on the main battery side. is there.

  Accordingly, an object of the present invention is to provide an in-vehicle power supply device in which power supply from the sub battery to the outside is not easily hindered due to a failure of the main battery or the like.

  The in-vehicle power supply device includes an in-vehicle main battery, a conductor portion that is normally in a conductive state and can be changed from the conductive state to the non-conductive state, and an in-vehicle auxiliary device connected via the conductor portion. A battery, a main power feeding end for feeding power from the main battery to the load, a sub power feeding end for feeding power from the sub battery to the load, and the conductor portion from the conductive state due to a voltage drop of the main battery. And a drive circuit for changing to a conductive state.

  According to such an in-vehicle power supply device, power supply from the sub battery to the outside is hardly hindered due to a failure of the main battery or the like.

It is a figure which shows the vehicle-mounted power supply device which concerns on embodiment. It is a figure which shows a part of vehicle-mounted power supply device concerning the deformation | transformation of embodiment.

  The on-vehicle power supply device according to the embodiment will be described below. FIG. 1 is a circuit diagram showing a connection relationship between an important load 6 and other general loads 5 and an in-vehicle power supply device 100 that supplies power to them.

<Configuration>
The in-vehicle power supply device 100 includes a main battery 1 (described as “main BAT” in the figure), a sub battery 2 (described as “sub BAT” in the figure), a relay 31, a drive circuit 32, a main power supply end 33a, and a sub power supply end. 33b. The general load 5 is a load that is not subject to backup of the sub-battery 2, and is, for example, an in-vehicle air conditioner. Since the general load 5 is a known load and does not have a characteristic characteristic in the present embodiment, detailed description thereof is omitted.

  The main battery 1 is charged from the outside of the in-vehicle power supply device 100. Specifically, the main battery 1 is connected to an on-vehicle alternator 9 (indicated by the symbol “ALT” in the figure) by a wiring L 9 and is charged by the power generation function of the alternator 9.

  The relay 31 functions as a normally closed type switch. That is, the relay 31 can be grasped as a conductor portion that is normally in a conductive state and can be changed from a conductive state to a non-conductive state.

  The sub battery 2 is connected to the main battery 1 via the wiring L2 and the relay 31, and can be charged by at least one of the alternator 9 and the main battery 1 when the relay 31 is in a conductive state. Yes. For example, a lead storage battery is used as the main battery 1, and a lithium ion battery is used as the sub battery 2, for example.

  The important load 6 is a load that is desired to maintain the power supply even when the power supply from the main battery 1 is lost. For example, a shift-by-wire actuator or an electronically controlled braking force distribution system can be cited as an example. .

  The in-vehicle power supply device 100 supplies power to the important load 6 using the main power supply end 33a and the sub power supply end 33b. The main power supply end 33 a is connected to the main battery 1 and is used for power supply from the main battery 1 to the important load 6. The sub power feeding end 33 b is connected to the sub battery 2 and is used for power feeding from the sub battery 2 to the important load 6.

  Diodes 61 and 62 are connected in series between the main power supply end 33a and the sub power supply end 33b with their forward directions being opposite to each other. Such a connection relationship between the diodes 61 and 62 is desirable from the viewpoint of preventing a current from flowing between the main battery 1 and the sub battery 2.

  Here, it is assumed that both the main battery 1 and the sub battery 2 supply a positive voltage with respect to a fixed potential. Therefore, the cathodes of the diodes 61 and 62 are connected to the important load 6 in common.

  The in-vehicle power supply device 100 preferably further includes a fuse connected in series between the general load 5 or the main power supply terminal 33a and the main battery 1 for overcurrent protection. In FIG. 1, a fuse box 4 that stores both a fuse connected in series between the general load 5 and the main battery 1 and a fuse connected in series between the main feeding end 33 a and the main battery 1 is illustrated. Has been. The fuse box 4 and the main battery 1 are connected by a wiring L4.

  The above-described wirings L2, L4, and L9 are realized by on-vehicle wiring called a so-called wire harness.

  The drive circuit 32 drives and opens the relay 31 due to the voltage drop of the main battery 1. Specifically, the drive circuit 32 has an input end 32a, an output end 32c, and a switch 32b. The voltage of the main battery 1 is input to the input terminal 32a. The switch 32b becomes conductive due to a voltage drop at the input end 32a. The output end 32 c is connected to the relay 31.

  The relay 31 has a relay coil 31a and a pair of contacts 31b. The series connection of the switch 32b and the relay coil 31a is connected to the sub battery 2 in parallel. The pair of contacts 31b are provided between the wiring L2 and the sub battery 2 and are turned off / on with respect to energization / non-energization of the relay coil 31a.

  By configuring the relay 31 and the drive circuit 32 in this way, the relay coil 31a is energized when the voltage of the main battery 1 drops, the pair of contacts 31b are turned off, and the sub battery 2 is connected from the wiring L2 to the main battery. The battery 1 is disconnected.

<Operation>
Since the relay 31 is a normally closed type, the main battery 1 and the sub battery 2 are connected in parallel as long as the drive circuit 32 does not pass a current to the relay coil 31a. Therefore, the in-vehicle power supply device 100 supplies power to the outside (in this case, the important load 6) from the main battery 1 through the main power supply end 33a or from the sub battery 2 through the sub power supply end 33b. In addition, the sub battery 2 can be charged from at least one of the main battery 1 via the wiring L2 and the alternator 9 via the wirings L9 and L2.

  Even when both the alternator 9 and the main battery 1 lose their power supply function, power supply from the sub battery 2 to the important load 6 is ensured via the sub power supply end 33 b and the diode 62.

  Further, in the present embodiment, when a ground fault occurs in the main battery 1, the drive circuit 32 causes a current to flow through the relay coil 31a, thereby opening the relay 31 (non-conducting state). As a result, when the voltage of the main battery 1 drops, the sub battery 2 can be disconnected from the wiring L2 and thus from the main battery 1, and the power supply from the sub battery 2 to the important load 6 via the sub power feeding end 33b is performed. It is hard to be disturbed by breakdowns. Since the diodes 61 and 62 are present as described above, it is also possible to prevent current from flowing from the auxiliary power supply end 33b to the main battery 1 via the main power supply end 33a.

  When the main battery 1 is not grounded but an open failure occurs, the relay 31 remains conductive. Therefore, in this case, power supply from the secondary battery 2 to the general load 5 via the wirings L2 and L4 and the fuse box 4 is also realized. Such an open failure does not interfere with the power supply by the secondary battery 2.

  As the switch 32b, for example, a P-channel field effect transistor can be adopted as illustrated. In this case, the input terminal 32a is connected to the gate of the transistor via a resistor. A series connection of the relay coil 31a and the sub battery 2 is connected between the drain and the source. Here, a case where the drain of the transistor is connected to the relay coil 31a via the output end 32c of the drive circuit 32 is exemplified.

  Or, even if the potential difference between the main battery 1 and the sub battery 2 is applied to the gate of the transistor via the input terminal 32a, it is obvious that the same effect is achieved according to the ground fault of the main battery 1.

<Deformation>
Instead of the relay 31, an inflator 31 'that is physically broken by energization may be employed. FIG. 2 is a diagram showing a part of the in-vehicle power supply device according to a modification of the above embodiment.

  The inflator 31 'has an ignition part 31c that ignites when a current flows, and a wiring 31d that is broken by the ignition. The ignition unit 31c is arranged in place of the relay coil 31a. That is, the series connection of the ignition unit 31 c and the switch 32 b (see FIG. 1) is connected in parallel to the sub battery 2. The wiring 31d is arranged in place of the pair of contacts 31b.

  The inflator 31 ′ can be grasped as a conductor portion that is in a conductive state under normal conditions and can be changed from a conductive state to a non-conductive state, like the relay 31.

  Even if such a deformation causes no ground fault in the main battery 1, the wiring 31d does not break, and the in-vehicle power supply device 100 connects the main battery 1 through the main power supply end 33a and the sub battery 2 through the sub power supply end 33b. Power is fed through. When a ground fault occurs in the main battery 1, the wiring 31 d is broken, and the sub battery 2 is disconnected from the wiring L 2 and thus from the main battery 1. Therefore, the same effects as those of the above embodiment can be obtained by such deformation.

  As described above, the present invention has been described in detail. However, the above description is illustrative in all aspects, and the present invention is not limited thereto. It is understood that countless variations that are not illustrated can be envisaged without departing from the scope of the present invention.

1 Main battery 2 Sub battery 6 Important load 31 Relay (conductor part)
31 'Inflator (conductor part)
31a Relay coil 31b A pair of contacts 31c Ignition section 31d Wiring 32 Drive circuit 32a Input end 32b Switch 33a Main power supply end 33b Sub power supply end 100 In-vehicle power supply device

Claims (3)

A main battery for in-vehicle use,
A conductor portion which is in a conductive state at normal time and can be changed from the conductive state to the non-conductive state;
An in-vehicle sub-battery connected to the main battery via the conductor,
A main power supply terminal for supplying power from the main battery to the load;
A sub-feeding end that feeds power from the sub-battery to the load;
A vehicle-mounted power supply device comprising: a drive circuit that changes the conductor portion from the conductive state to the non-conductive state due to a voltage drop of the main battery. The in-vehicle power supply device according to claim 1,
The drive circuit is
An input terminal for inputting the voltage of the main battery;
A switch that conducts due to a voltage drop at the input end,
The conductor portion is a relay coil whose series connection with the switch is connected in parallel to the sub battery,
An in-vehicle power supply device having a pair of contacts that are turned off / on with respect to energization / non-energization of the relay coil between each other. The in-vehicle power supply device according to claim 1,
The drive circuit is
An input terminal for inputting the voltage of the main battery;
A switch that conducts due to a voltage drop at the input end,
The conductor portion is
An ignition unit in which a series connection with the switch is connected in parallel to the sub battery,
A vehicle-mounted power supply device that is an inflator having a wiring that is broken by the ignition unit.

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