JP2015150956A - Battery system for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery system for a vehicle suppressing occurrence of start failure of an engine by eliminating insufficient charging of a first storage battery that supplies electric power to a starter.SOLUTION: A battery system for vehicle is equipped with first and second storage batteries mounted on a vehicle that contains an engine. In a case where a charge rate of a first storage battery 11 is a charge start threshold value or less with no power generation margin, inner opening/closing means 24 of a second storage battery 12 is controlled to be an open state.

Description

  The present invention relates to a vehicle battery system including first and second storage batteries mounted on a vehicle including an engine, and more particularly to charging of first and second storage batteries by power generation by an alternator.

  For vehicles such as automobiles, lamps such as headlights, small lights, brake lamps, interior lights, drive motors such as power windows, wipers, air conditioners and radiator fans, starters at the start of engines, audio, navigation Various electric devices (electric loads) such as devices are mounted. And the electric power consumed by these electric loads is supplied by the storage battery which can be charged / discharged. Further, the vehicle is provided with an alternator (generator) driven by an engine, and the storage battery is appropriately charged with electric power generated by the alternator.

  In recent years, vehicles equipped with a plurality of storage batteries have been put into practical use in order to increase the electric load and improve the fuel efficiency of the vehicle. For example, a first storage battery that is a lead battery for supplying electric power to an electric load including a starter for starting the engine, and a second storage battery that is connected in parallel to the first storage battery. There is something that was made.

  In the vehicle battery system provided with such a first storage battery and a second storage battery, the first and second storage batteries may be charged simultaneously. Specifically, for example, an opening / closing means such as a relay is arranged in a connection wiring connecting the alternator and the lead storage battery (first storage battery) and the lithium ion storage battery (second storage battery), and the opening / closing means is opened and closed. Charging and discharging from the second storage battery are controlled (see Patent Document 1).

JP 2013-198318 A

  If it is going to charge the 1st storage battery and the 2nd storage battery simultaneously as mentioned above, the 1st and 2nd storage battery cannot fully be charged, but the charge amount of each storage battery will fall extremely. There is a fear. For example, in a situation where the power consumed by the electric load during idling is relatively large, etc., there is a possibility that the alternator has a small power generation margin and each storage battery cannot be charged.

  And if the charge amount of the 1st storage battery falls extremely, when starting an engine after that, a starter cannot be operated satisfactorily and there exists a possibility of causing starting failure of an engine.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a vehicle battery system capable of suppressing the occurrence of engine start failure by eliminating insufficient charging of the first storage battery. To do.

  According to a first aspect of the present invention for solving the above-mentioned problems, a first storage battery for supplying power to a starter for starting an engine, a first storage battery connected in parallel with the first storage battery, and the first storage battery A vehicle battery system comprising: a second storage battery having an internal opening / closing means for switching a connection state between the first storage battery and an alternator connected to the first storage battery and the second storage battery to generate electric power by driving the engine, Charge state detection means for detecting a charge state of the first storage battery; charge control means for controlling the power generation state of the alternator and the open / close state of the internal opening / closing means based on a detection result of the charge state detection means; and the alternator Power generation margin determination means for determining whether or not there is a power generation margin, and the charge control means is configured to determine a charging rate of the first storage battery by the charge state detection means. When the vehicle is detected to be equal to or less than a predetermined charging start threshold, and the power generation margin determining means determines that there is no power generation margin, the internal opening / closing means is controlled to be opened. In the battery system.

  In the first aspect, the occurrence of insufficient charging of the first storage battery can be suppressed, and the starter can be driven well when the engine is started.

  According to a second aspect of the present invention, in the vehicular battery system according to the first aspect, the charge control means controls the internal opening / closing means to an open state, and then the charge state detection means causes the first storage battery to In the vehicle battery system, the internal opening / closing means is controlled to be closed when it is detected that the charging rate is equal to or higher than a predetermined charging end threshold value higher than the charging start threshold value.

  In the second aspect, the number of operations of the internal opening / closing means can be minimized.

  According to a third aspect of the present invention, in the vehicle battery system according to the first or second aspect, a first electric circuit including the starter and the first storage battery, and a second electric circuit including the second storage battery. A battery system for a vehicle, further comprising an external opening / closing means capable of interrupting a flow of electricity from the second electric circuit side to the first electric circuit side in a connection wiring connecting the circuit. It is in.

  In the third aspect, even when the engine is started in a state where the flow of electricity from the second electric circuit side to the first electric circuit side is blocked by the external opening / closing means unit, the starter is operated well. Therefore, it is possible to suppress the occurrence of engine start failure.

  In this invention, the extreme fall of the charge amount of a 1st storage battery can be suppressed. Therefore, the starter can always be operated satisfactorily by supplying power from the first storage battery, and the occurrence of engine start failure can be suppressed.

It is a figure showing composition of a battery system for vehicles concerning one embodiment of the present invention. It is a figure showing composition of a battery system for vehicles concerning one embodiment of the present invention. It is a figure showing composition of a battery system for vehicles concerning one embodiment of the present invention.

  Hereinafter, a vehicle battery system according to an embodiment of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, a vehicle battery system 10 according to the present embodiment supplies power to various electric loads mounted on a vehicle, and includes a first storage battery 11 and a second storage battery 12. It has a storage battery. The first storage battery 11 is composed of a lead battery, and the second storage battery 12 is composed of a nickel metal hydride battery or a lithium ion battery. The second storage battery 12 according to this embodiment includes a battery cell unit 13, and although not shown, the battery cell unit 13 includes a plurality of, for example, about 10 battery cells (nickel metal hydride batteries) in series. Connected to and configured.

  The first storage battery 11 and the second storage battery 12 are connected in parallel. Specifically, the vehicle battery system 10 includes a first electric circuit 14 including a first storage battery 11 and a second electric circuit 15 including a second storage battery 12, and the first electric circuit 14 includes the first electric circuit 14 including the first storage battery 11. The electric circuit 14 and the second electric circuit 15 are connected via a connection wiring 16.

  The first electric circuit 14 includes, together with the first storage battery 11, an alternator (generator) 18 that is driven by the engine 17 to generate electric power, a starter 19 for starting the engine 17, and a first electric load 20. Are connected in parallel. Further, the first electric circuit 14 is provided with a battery sensor (first charge state detection means) 21 for detecting a charge state of the first storage battery 11, for example, a charge rate (SOC), a temperature and the like. The first electric load 20 is an electric load that may be restarted when the engine 17 is started, that is, an electric load that causes no problem if electric power is supplied while the vehicle is running. A headlamp, a heater, etc. are mentioned.

  On the other hand, the second electric circuit 15 is configured by connecting the second storage battery 12 and the second electric load 22 in parallel. In contrast to the first electrical load 20, the second electrical load 22 is preferably an electrical load that is not restarted when the engine 17 is started. For example, a car navigation device, audio, or the like can be given. It is done. Note that the separation of the first electric load 20 and the second electric load 22 of various electric loads is not limited to the above-described one, and may be appropriately set as necessary.

  The connection wiring 16 that connects the first electric circuit 14 and the second electric circuit 15 cuts off the flow of electricity from the second electric circuit 15 side to the first electric circuit 14 side. A possible external relay unit (external opening / closing means) 23 is provided. The external relay unit 23 includes a rectifying unit 23b formed of a diode together with the switch unit 23a.

  As shown in FIG. 1, when the switch unit 23a is in the closed state (connected state), the charging state of the first storage battery 11 and the second storage battery 12, the power generation state of the alternator 18, the first and second electric power The flow of electricity from the first electric circuit 14 side to the second electric circuit 15 side also changes from the second electric circuit 15 side to the first electric power according to the power consumption consumed by the loads 20 and 22 and the like. An electrical flow to the circuit 14 side can also occur. That is, electric power may be supplied from the first storage battery 11 or the alternator 18 to the second electric load 22, or electric power may be supplied from the second storage battery 12 to the first electric load 20.

  For example, when the engine 17 is in operation and the charge amount of the second storage battery 12 is sufficient, the switch unit 23a is controlled to be closed. In this state, power is supplied to the first electrical load 20 not only from the first storage battery 11 but also from the second storage battery 12. Thereby, the electric power generation amount of the alternator 18 can be suppressed, and the fuel consumption can be improved accordingly.

  On the other hand, as shown in FIG. 2, when the switch portion 23a is in the open state (disconnected state), only the flow of electricity from the second electric circuit 15 side to the first electric circuit 14 side is blocked. That is, the flow of electricity from the first electric circuit 14 side to the second electric circuit 15 side is maintained by the rectifying unit 23b provided in the external relay unit 23 as indicated by an arrow in the figure. Therefore, in this state, power may be supplied from the first storage battery 11 or the alternator 18 to the second electrical load 22, but power is supplied from the second storage battery 12 to the first electrical load 20. It will never be done.

  Furthermore, the second storage battery 12 includes, for example, a mechanical internal relay (internal opening / closing means) 24, and is configured so that the connection state between the battery cell unit 13 and the connection wiring 16 can be appropriately switched by the internal relay 24. ing. The internal opening / closing means 24 may be constituted by a semiconductor relay or the like in addition to the mechanical relay.

  The external relay unit 23 and the internal relay 24 are appropriately controlled by a battery control unit (BMU) 26 based on a signal from the ECU 25. The BMU 26 controls a battery sensor (first charge state detection means) that detects the charge state of the battery cell unit 13 constituting the second storage battery 12, the external relay unit 23, and the internal relay 24. It consists of a control unit. The BMU 26 is provided in the second storage battery 12 in this embodiment, but may be provided separately from the second storage battery 12.

  The ECU (electronic control unit) 25 includes an input / output device, a storage device that stores a control program, a control map, and the like, a central processing unit, timers and counters, and based on information from various sensors, The overall control of the engine 17 including the starter 19 and the like is performed.

  The ECU 25 also serves as a part of the vehicle battery system 10 according to the present embodiment. For example, the ECU 25 controls the open / close state of the external relay unit 23 and the internal relay 24 via the BMU 26 as described above, and appropriately controls the power generation state (power generation amount) of the alternator 18. Thereby, the charging state (charging rate) of the 1st storage battery 11 and the 2nd storage battery 12 is controlled suitably, supplying desired electric power to various electric loads.

  Hereinafter, an example of storage battery charging control in the vehicle battery system 10 will be described.

  The ECU 25 includes a charge control means 27 and a power generation margin determination means 28 as means for controlling the charging state (charging rate) of the first storage battery 11 and the second storage battery 12.

  The charging control means 27 controls the power generation amount of the alternator 18 according to the charging state (charging rate) of the first storage battery 11 and the second storage battery 12 to charge the first storage battery 11 and the second storage battery 12. Run. In the present embodiment, the battery sensor (first charge state detection means) 21 detects the charge state of the first storage battery 11, and the BMU (second charge state detection means) 26 detects the charge state of the second storage battery 12. Is detected. Then, the charge control means 27 drives the engine 17 so that the power generation amount by the alternator 18 becomes a desired value based on the detection result by the battery sensor 21 and the BMU 26 as well as the driving state and environmental state of the vehicle. Control as appropriate.

  When the first storage battery 11 or the second storage battery 12 is discharged, that is, when the charge rate (SOC) of the first storage battery 11 or the second storage battery 12 is equal to or lower than the charging start threshold, The power generation of the alternator 18 is started and charging of the first storage battery 11 or the second storage battery 12 is started. Then, when the charging end threshold is reached, the power generation of the alternator 18 is ended.

  The charging start threshold and the charging end threshold are appropriately determined according to the characteristics of the storage batteries 11 and 12. In this embodiment, the charging start threshold of the first storage battery 11 is set to 90% and the charging end threshold is set to 95%, the charging start threshold of the second storage battery 12 is set to 30% and the charging end threshold is set to 50%. ing.

  At normal time, the charging control means 27 places the internal relay 24 in a connected state when charging the first storage battery 11 and the second storage battery 12 (see FIG. 1). In this state, as indicated by an arrow in the figure, the electric power generated by the alternator 18 is supplied to the first storage battery 11 and the second storage battery 12, and the storage batteries 11 and 12 are charged simultaneously. The term “normal time” as used herein refers to a state in which one or both of the first storage battery 11 and the second storage battery 12 has a discharge tendency, that is, a charge start threshold value or less, but there is a power generation margin of the alternator 18. Say. For example, a state in which the charging rate of the first storage battery 11 is equal to or less than the charging start threshold (90%), but a power generation margin rate of an alternator 18 described later is equal to or greater than a predetermined value corresponds to “normal time”.

  Thereafter, when the charging rate (SOC) of the first storage battery 11 or the second storage battery 12 becomes equal to or higher than the charging end threshold, the power generation amount of the alternator 18 by the engine 17 is suppressed, and the charging of the storage batteries 11 and 12 is ended.

  As described above, the charging control means 27 controls the power generation of the alternator 18 in accordance with the charging states of the first storage battery 11 and the second storage battery 12 at normal times. As described below, the first storage battery 27 11, the internal relay 24 of the second storage battery 12 is opened depending on the state of charge (charge rate) 11 and the determination result of the power generation margin determination means 28.

  The power generation margin determining means 28 determines whether the alternator 18 has a power generation margin. In the present embodiment, it is determined whether the power generation margin of the alternator 18 is equal to or less than a predetermined value. The charge margin (power generation margin rate) is a value indicating how much margin is left in the power generation state of the alternator 18. Specifically, the sum of the amount of power consumed by the first and second electric loads 20 and 22 and the amount of power required to charge the first storage battery 11 and the second storage battery 12. It is a ratio between the value and the maximum power generation amount of the alternator 18. For example, when the total value is equal to or greater than the maximum power generation amount of the alternator 18, the power generation margin rate is 0%.

  The power generation margin determining means 28 determines whether or not there is a power generation margin of the alternator 18, but “no power generation margin” here does not necessarily mean a state where the power generation margin rate is 0%. For example, when the power generation margin rate is temporarily below a predetermined value or when it takes too much time to charge the first storage battery 11 and the second storage battery 12, both the storage batteries 11 and 12 are charged. It also includes a state where there is no room. In the present embodiment, the power generation margin determination unit 28 determines that “there is no power generation margin” when the power generation margin rate is equal to or less than a predetermined value (for example, about 10%).

  The charge control means 27 detects that the charging rate of the first storage battery 11 is equal to or less than the charge start threshold (90%), and further determines that “there is no power generation margin” by the power generation margin determination means 28. That is, when it is determined that the power generation margin is equal to or less than the predetermined value, as shown in FIG. 3, the internal relay 24 included in the second storage battery 12 is controlled via the BMU 26 to open the internal relay 24 ( Disconnected state). As a result, as indicated by an arrow in the figure, the electric power generated by the alternator 18 is supplied to the first storage battery 11 without being supplied to the second storage battery 12.

  Thereby, the 1st storage battery 11 can be charged efficiently. For example, even when the engine 17 is in an idling state and the power consumption consumed by the first electric load 20 and the second electric load 22 is relatively large, the first storage battery 11 is reliably charged. be able to. Therefore, when the engine 17 is subsequently started, the starter 19 can be driven satisfactorily, and the occurrence of start failure of the engine 17 can be suppressed.

  In the vehicle battery system 10 according to the present embodiment, when the engine 17 is started, the switch portion 23a of the external relay unit 23 is in a disconnected state from the viewpoint of safety (see FIG. 2). In this state, the flow of electricity from the first electric circuit 14 side to the second electric circuit 15 side is maintained via the rectifier 23b as described above, but the second electric circuit 15 to the first electric circuit 15 The flow of electricity to the electric circuit 14 side is cut off. Therefore, when the engine 17 is started, the starter 19 is driven only by the electric power supplied from the first storage battery 11. For this reason, if the first storage battery 11 is insufficiently charged, the starter 19 may not be operated satisfactorily.

  However, by opening the internal relay 24 as necessary as described above, the first storage battery 11 can be appropriately charged, and the starter 19 can be operated satisfactorily. Therefore, starting failure of the engine 17 can be suppressed.

  Further, such preferential charging of the first storage battery 11 is terminated when the charging rate of the first storage battery 11 is equal to or higher than the charge end threshold (95%) higher than the charge start threshold, and the second storage battery 12 charging is resumed. Specifically, when the charging rate of the first storage battery 11 is equal to or higher than the charging end threshold, the charging control unit 27 controls the internal relay 24 to be closed (connected state). Thereby, the electric power generated by the alternator 18 is supplied to each of the first storage battery 11 and the second storage battery 12 (see FIG. 1).

  The preferential charging of the first storage battery 11 may be terminated when the above-described start conditions (the charging rate and the power generation margin rate of the first storage battery 11) are not satisfied. It is preferable that the storage battery 11 is terminated when the charging rate of the storage battery 11 becomes equal to or higher than a charging termination threshold.

  If the preferential charging of the first storage battery 11 is terminated when the start condition is no longer satisfied, the internal relay 24 may be frequently opened and closed depending on the driving state of the vehicle. When the internal relay 24 is opened / closed, a relatively loud sound is generated. Therefore, if the opening / closing control of the internal relay 24 is frequently performed, there is a possibility that the passenger may feel uncomfortable. In particular, when the second storage battery 12 is disposed under the floor of the vehicle, it is easy to give the passenger discomfort. However, when the charging rate of the first storage battery 11 becomes equal to or higher than the charging end threshold, the number of opening / closing operations of the internal relay 24 associated with the charging of the first storage battery 11 and the second storage battery 12 is minimized. Can be suppressed.

  As mentioned above, although one Embodiment of this invention was described, of course, this invention is not limited to the above-mentioned embodiment, In the range which does not deviate from the meaning, it can change suitably.

DESCRIPTION OF SYMBOLS 10 Vehicle battery system 11 1st storage battery 12 2nd storage battery 13 Battery cell unit 14 1st electric circuit 15 2nd electric circuit 16 Connection wiring 17 Engine 18 Alternator 19 Starter 20 1st electric load 21 Battery sensor ( First charge state detection means)
22 Second electrical load 23 External relay unit (external switching means)
23a Switch part 23b Rectification part 24 Internal relay (internal switching means)
25 ECU
26 BMU (second charge state detection means)
27 Charging control means 28 Power generation margin judging means

Claims (3)

A first storage battery for supplying power to a starter for starting the engine;
A second storage battery connected in parallel with the first storage battery and having an internal opening / closing means for switching the connection state with the first storage battery;
An alternator connected to the first and second storage batteries and generating electric power by driving the engine;
A vehicle battery system comprising:
Charge state detection means for detecting a charge state of the first storage battery;
Charge control means for controlling the power generation state of the alternator and the open / close state of the internal open / close means based on the detection result of the charge state detection means;
Power generation margin determination means for determining whether there is a power generation margin of the alternator,
The charge control means includes
When it is detected by the charging state detection means that the charging rate of the first storage battery is equal to or less than a predetermined charging start threshold, and further when the power generation margin determination means determines that there is no power generation margin, A vehicle battery system, wherein the opening / closing means is controlled to be in an open state. The vehicle battery system according to claim 1,
After the charge control means controls the internal opening / closing means to be in an open state, the charge state detection means causes the charge rate of the first storage battery to be equal to or higher than a predetermined charge end threshold value higher than the charge start threshold value. When this is detected, the internal opening / closing means is controlled to be closed. The vehicle battery system according to claim 1 or 2,
The first electric circuit is connected to the first electric circuit including the starter and the first storage battery and the second electric circuit including the second storage battery from the second electric circuit side. A vehicle battery system, further comprising external opening / closing means capable of interrupting the flow of electricity to the circuit side.

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