JP4844440B2 - Battery charger - Google Patents

Description

  The present invention relates to a battery charger for supplying electric power to an electric load during idling stop, and belongs to the field of battery charge / discharge control.

  Conventionally, there are vehicles described in Patent Document 1 and Patent Document 2 in which two batteries are mounted in a vehicle that performs idling stop. These take into consideration that the starter supplied with power from the battery has more opportunities to start the engine than a vehicle that does not perform idling stop. The former includes a battery that supplies power to the starter when the vehicle is started, and a battery that supplies power to the starter when the engine that is idling is restarted. On the other hand, in the latter, one of the two batteries is mounted as a spare. In this way, the engine is reliably started by the starter.

JP 2005-36795 A Japanese Patent No. 3812259

  However, when two batteries are mounted, the two batteries are charged by one alternator, and the battery may be deteriorated depending on the charging method. For example, when charging two batteries at the same time, if one battery is fully charged and the other battery is not fully charged, one battery is fully charged until the other battery is fully charged Nevertheless, it will be charged. That is, one battery is overcharged. If this overcharge continues for a long time (when it takes time until the other battery is fully charged), one battery may be deteriorated.

  Therefore, an object of the present invention is to provide a battery charging device that can suppress deterioration of each battery in a vehicle equipped with two batteries that are charged simultaneously.

In order to solve the above-described problem, the invention according to claim 1 of the present application stops an engine when a predetermined idling stop condition is satisfied, and stops idling when a predetermined restart condition is satisfied. A battery charging device comprising: an automatic stop control means for restarting the power supply; a first battery for supplying power to the electric load during idling stop; and a second battery for supplying power to the starter. A generator that is always connected to the first battery and capable of changing a power generation voltage, a switching means that connects or disconnects the power generator and the second battery, and a power generation voltage of the power generator. by controlling the state of said switching means, a charge control unit that controls charging for said first battery and said second battery, the first battery and before And a charging state detecting means for detecting a state of charge of the second battery, said charging control means, said charging state detection means, the first battery and the second battery is not both fully charged Is detected, the switching means is set to the connected state and the power generation voltage of the generator is set to the Hi voltage to charge the first battery and the second battery, and then the charge state detecting means However , when it is detected that the second battery is in a fully charged state before the first battery , the switching means is turned off, and only the first battery is charged with the Hi voltage, said charging state detection means, wherein when the first battery is detected that been fully charged earlier than the second battery is a predetermined value reduction than the Hi voltage generated voltage of the generator Characterized in that charging the second battery Te.

  According to a second aspect of the present invention, in the battery charging device according to the first aspect, the capacity of the second battery is set smaller than that of the first battery.

  According to the first aspect of the present invention, the generator that charges the first battery that is always connected and the second battery that is selectively connected by the switching means is configured to change the generated voltage. . If the second battery is first fully charged while the two batteries are being charged, the second battery and the generator are disconnected via the switching means. Thereby, the second battery in the fully charged state is charged until the first battery is fully charged, that is, overcharge of the second battery is suppressed. As a result, the deterioration of the second battery is suppressed.

  On the other hand, when the first battery is fully charged during charging of the two batteries, the power generation voltage of the generator is reduced by a predetermined value. Thereby, the voltage applied to the fully charged first battery is low until the second battery is fully charged. Thereby, although the charging of the first battery is continued, the applied voltage is low, so that the overcharging of the first battery is suppressed as compared with the case where the power generation voltage of the generator is not reduced by a predetermined value. As a result, deterioration of the first battery is suppressed.

  According to the invention described in claim 2, the capacity of the second battery is set smaller than that of the first battery. Thereby, in charge of two batteries, possibility that a 2nd battery will be in a full charge state before a 1st battery becomes high. Accordingly, the first battery is prevented from being charged until the first battery is fully charged before the second battery and the first battery is fully charged until the second battery is fully charged. The battery is less likely to be overcharged. As a result, deterioration of the first battery is suppressed.

  FIG. 1 shows an electric system of a vehicle according to an embodiment of the present invention. The system 10 includes a starter 14 for starting an engine 12, an alternator 16 driven by the engine 12 to generate electric power, An electric load (for example, an AT pump) 18 that is driven by the electric power generated by the alternator 16, a main battery (corresponding to the first battery described in the claims) 20 that stores the electric power generated by the alternator 16, and a sub. A battery (corresponding to the second battery) 22, a power relay 24, and a charge relay (corresponding to switching means) 26 are included.

  The engine 12 is configured to be executed by the starter 14 when starting the vehicle or restarting after returning from the idling stop state.

  The alternator 16 is configured to be able to change the setting of the generated voltage to a predetermined high voltage (Hi voltage) and a predetermined low voltage (Low voltage). The predetermined value described in the claims corresponds to the difference between the Hi voltage and the Low voltage.

  The main battery 20 is mainly for supplying electric power to the electric load 18, and is mounted on the vehicle as a dedicated battery for supplying electric power to the electric load 18 that is driven during idling stop. The main battery 20 is always connected to the alternator 16, and when the alternator 16 is driven by the engine 12, the main battery 20 stores a part of the electric power generated by the alternator 16 (the remainder is supplied to the electric load 18). . The main battery 20 is always connected to the electric load 18, and the electric load 18 is started (for example, the car navigation system, which is an electric load, is started when an occupant pushes a start switch, or an ignition key is occupant). When the AT pump, which is an electric load, is started by turning on the electric load, the electric load 18 starts to be supplied with electric power.

  Further, the main battery 20 is connected to the starter 14 via the power relay 24 and selectively supplies power to the starter 14. The timing at which the main battery 20 supplies power to the starter 14 will be described later.

  The sub-battery 22 is mounted on the vehicle as a dedicated battery that supplies power to the starter 14. The sub-battery 22 is always connected to the starter 14 and starts supplying power to the starter 14 when the starter 14 starts.

  The sub-battery 22 is connected to the alternator 16 via the charge relay 26, and is selectively connected to the alternator 16 for charging.

  The power relay 24 is configured to connect the main battery 20 and the starter 14 when the ignition key is turned on by the occupant and the starter 14 starts the engine 12 (not including restart of the engine that has stopped idling). ing. Other than that, the main battery 20 and the starter 14 are disconnected.

The charge relay 26 is configured to disconnect the alternator 16 and the sub battery 22 during idling stop. Further, while the engine 12 is being driven, the alternator 16 and the sub-battery 22 are connected only when the sub-battery 22 is charged, and the others are disconnected.

  Further, as shown in FIG. 2, the vehicle has a control system 50 centered on an engine control unit (ECU) 52. The control system 50 centering on the ECU 52 includes a main battery current sensor 54 and a sub battery current sensor 56.

  The main battery current sensor 54 is configured to detect a value of current flowing in and out of the main battery 20 and to output a signal corresponding to the detected value to the ECU 52.

  The sub-battery current sensor 56 is configured to detect a value of current flowing into and out of the sub-battery 22 and to output a signal corresponding to the detected value to the ECU 52.

  The ECU 52 is configured to output control signals to the engine 12, the starter 14, the alternator 16, the switch 24, and the switch 26.

  Specifically, the ECU 52 is configured to stop the engine 12 when a predetermined idling stop condition is satisfied. The predetermined idling stop condition is satisfied, for example, when a passenger pauses the vehicle and a few seconds elapse. For example, when the vehicle speed is zero, the vehicle speed sensor (not shown) detects that the vehicle speed is zero, and the ignition key switch (not shown) detects that the ignition key is turned on for a few seconds. Is done.

  Further, the ECU 52 restarts the engine 12 when detecting that the occupant has requested to start the vehicle during the idling stop. In addition, it can confirm that a passenger | crew requested | required start of a vehicle, for example by detecting the operation | movement which an accelerator pedal sensor (not shown) steps on an accelerator pedal.

  From here, the control regarding the charge with respect to the main battery 20 and the subbattery 22 which ECU52 performs is demonstrated.

  First, the ECU 52 is configured to monitor (monitor) the states of the main battery 20 and the sub battery 22 based on signals output from the main battery current sensor 54 and the sub battery current sensor 56. This is for detecting that the main battery 20 and the sub battery 22 are fully charged. The alternator 16 and the charge relay 26 are controlled based on the state of the main battery 20 and the sub battery 22 being monitored.

  In the normal mode, the ECU 52 causes the alternator 16 to generate electric power while maintaining the generated voltage at the low voltage, and causes the charge relay 26 to disconnect the alternator 16 and the sub-battery 22. That is, only the main battery 20 is charged.

  Further, the ECU 52 executes a simultaneous charging mode in which both the main battery 20 and the sub battery 22 are charged simultaneously.

  This simultaneous charging mode is started after the engine 12 is started when the vehicle is started or after the engine 12 is restarted while idling is stopped.

  After the engine 12 is started at the time of starting the vehicle, the power stored in the main battery 20 and the sub battery 22 is supplied to the starter 14 and the engine 12 is started. Therefore, the main battery 20 and the sub battery 22 are not fully charged. Therefore, the ECU 52 executes the simultaneous charging mode.

  On the other hand, even after restarting the engine 12 during idling stop, the power stored in the sub battery 22 is supplied to the starter 14 and the engine 12 is started, so the sub battery 22 is not fully charged. Moreover, since the main battery 20 is also supplying electric power to the electric load 18 during idling stop, it is not in a fully charged state. Therefore, the ECU 52 executes the simultaneous charging mode.

  The simultaneous charging mode is started when the power generation voltage of the alternator 14 is set to the Hi voltage. That is, the main battery 20 and the sub battery 22 are rapidly charged.

  The simultaneous charging mode is completed when either the main battery 20 or the sub-battery 22 is fully charged first and the other battery is fully charged after a delay. That is, the mode is shifted from the simultaneous charging mode to the normal mode.

  This will be described with reference to FIGS.

  First, when the simultaneous charging mode is executed, the sub battery 22 is fully charged before the main battery 20 (FIG. 3) and the main battery 20 is fully charged before the sub battery 22 (FIG. 4). )

  The ECU 52 monitors the charging current of the main battery 20 and the sub-battery 22 based on the outputs from the main battery current sensor 54 and the sub-battery current sensor 56 during the simultaneous charging mode, and as shown in FIG. When the charging current (solid line) 22 becomes equal to or lower than the determination current before the charging current (one-dot chain line) of the main battery 20, it is determined that the sub-battery 22 is fully charged before the main battery 20. The value of the determination current is a value indicating that the battery is fully charged when the value is less than or equal to this value.

  When the sub battery 22 is fully charged, the ECU 52 causes the charge relay 26 to disconnect the alternator 14 and the sub battery 22. Thereby, the charging of the sub battery 22 is terminated while the charging of the main battery 20 is continued. In other words, the fully charged sub battery 22 is prevented from being overcharged until the main battery 20 is fully charged. As a result, the deterioration of the sub battery 22 is suppressed.

  Subsequently, when the charging current of the main battery 20 becomes equal to or lower than the determination current, the ECU 52 determines that the main battery 20 is fully charged, and the ECU 52 changes the power generation voltage of the alternator 14 from the Hi voltage to the Low voltage. Change to That is, the simultaneous charging mode is completed and the normal mode is entered.

  On the other hand, as shown in FIG. 4, when the charging current of the main battery 20 becomes a determination value or less before the charging current of the sub-battery 22, the ECU 52 causes the main battery 20 to be fully charged before the sub-battery 22. It is determined that it has become.

  When the main battery 20 is fully charged, the ECU 52 changes the power generation voltage of the alternator 16 from the Hi voltage to the Low voltage. Thus, the voltage applied to the fully charged main battery 20 is lowered until the sub battery 22 is fully charged. Although charging of the main battery 20 is continued, the applied voltage is low, so overcharging of the main battery 20 is suppressed as compared with the case where the power generation voltage of the alternator 16 is maintained at the Hi voltage without changing to the Low voltage. As a result, deterioration of the main battery 20 is suppressed.

  Subsequently, when the charging current of the sub-battery 22 becomes equal to or less than the determination current, that is, when the sub-battery 22 is fully charged, the ECU 52 causes the charge relay 26 to disconnect the alternator 14 and the sub-battery 22. Then, the simultaneous charging mode is completed and the normal mode is entered.

  An example of the flow of this simultaneous charging mode will be described with reference to the flow shown in FIG.

  First, as shown in the figure, the ECU 52 starts the engine 12 with the starter 14 (S100). If the start is when the vehicle is started, the power of the main battery 20 and the sub battery 22 is supplied to the starter 14. On the other hand, when restarting the engine during idling stop, the power of the sub-battery 22 is supplied to the starter 14.

  Next, in S110, the ECU 52 starts reading signals from the main battery current sensor 54 and the sub battery current sensor 56. That is, monitoring of the state of the main battery 20 and the sub battery 22 is started.

  Subsequently, in S120, the ECU 52 turns on the charge relay to connect the alternator 16 and the sub battery 22. Thereby, simultaneous charging of the main battery 20 and the sub battery 22 is started.

  In S130 after S120, the ECU 52 changes the power generation voltage of the alternator 16 from the Low voltage to the Hi voltage. Start fast charging.

  In S140, the ECU 52 confirms whether or not the sub-battery 22 is fully charged based on the signal from the sub-battery current sensor 56 that has started reading in S110. If confirmed, in S150, the charge relay 26 is turned off and the alternator 16 and the sub-battery 22 are disconnected. Subsequently, when the fully charged state of the main battery 20 is confirmed in S160, the power generation voltage of the alternator 14 is changed to a Low voltage in S170, and signals are read from the main battery current sensor 54 and the sub battery current sensor 56 in S220. End the simultaneous charging mode (transfer to the normal charging mode).

  On the other hand, if it is not confirmed in S140 that the sub-battery 22 is fully charged, in S180, the ECU 52 is fully charged based on the signal from the main battery current sensor 54 that has started reading in S110. Check if it is in a state. When it is confirmed, the generated voltage of the alternator 14 is changed to a low voltage in S190. Subsequently, when the fully charged state of the sub battery 22 is confirmed in S200, the alternator 16 and the sub battery 22 are disconnected by turning off the charge relay 26 in S210. Then, in S220, reading of the signals from the main battery current sensor 54 and the sub battery current sensor 56 is finished, and the simultaneous charging mode is finished (transition to the normal charging mode).

  If the fully charged state of the main battery 20 is not confirmed in S180, the process returns to S140.

  Although the present invention has been described with reference to the above-described embodiment, the present invention is not limited to this.

  For example, in the above-described embodiment, the capacities (maximum chargeable amount) of the main battery and the sub battery are not limited, but the capacity of the sub battery may be set smaller than that of the main battery.

  In this case, if two batteries are charged simultaneously (when the above-described simultaneous charging mode is executed), the possibility that the sub-battery is fully charged before the main battery is higher than that in the above-described embodiment. Thus, the main battery is prevented from being charged until the main battery is fully charged before the sub battery and the sub battery is fully charged, that is, the main battery is less likely to be overcharged. Become. As a result, deterioration of the main battery is suppressed.

  In the normal mode described above, when it is detected that the stored amount of the main battery is equal to or lower than a predetermined lower limit amount based on a signal from the main battery current sensor (when a current value corresponding to the predetermined lower limit amount is detected) ) In order to charge the main battery with a larger charge amount, the ECU may be configured to set the power generation voltage of the alternator to the Hi voltage. The predetermined lower limit is a value that may cause the battery to deteriorate when the predetermined lower limit is reached. In this case, after detecting that the main battery is fully charged, the power generation voltage of the alternator is returned to the Low voltage. As a result, deterioration of the main battery due to the amount of electricity stored in the main battery being equal to or less than the lower limit amount is suppressed.

  Furthermore, when it is detected that the storage amount of the sub battery has become equal to or less than a predetermined lower limit amount based on the signal of the sub battery current sensor in the normal mode (when a current value corresponding to the predetermined lower limit amount is detected). In order to charge the sub-battery, the ECU may be configured to control the charge relay to connect the alternator and the sub-battery. The predetermined lower limit is a value that may cause the battery to deteriorate when the predetermined lower limit is reached. Thereby, the deterioration of the sub-battery due to the amount of power stored in the sub-battery being equal to or lower than the lower limit amount is suppressed.

  In this case, when the amount of power stored in the sub-battery becomes equal to or less than the predetermined lower limit amount, the control content related to charging performed by the ECU differs depending on whether or not the main battery is fully charged.

  If the main battery is in a fully charged state when the amount of electricity stored in the sub-battery falls below a predetermined lower limit amount, the sub-battery is charged while maintaining the power generation voltage of the alternator at the low voltage. That is, the same control as that performed when the main battery is fully charged first in the simultaneous charging mode described above is executed. This suppresses the main battery from being overcharged until the sub battery is fully charged.

  On the other hand, if the main battery is not fully charged when the amount of power stored in the sub-battery is equal to or less than the predetermined lower limit, that is, if both the two batteries are not fully charged, the above-described simultaneous charging mode is executed.

  As described above, according to the present invention, when two batteries are mounted in a vehicle that performs idling stop, charging that suppresses deterioration of the two batteries is possible. Therefore, there is a possibility of being suitably used in the field of manufacturing industries for vehicles that perform idling stop.

1 is a diagram schematically showing an electric system of a vehicle including a battery charging device according to an embodiment of the present invention. It is a figure which shows roughly the control system of the vehicle containing the charging device of the battery concerning one Embodiment of this invention. It is a figure which shows the control in case a sub battery becomes a full charge state previously. It is a figure which shows the control in case a main battery will be in a full charge state previously. It is a figure which shows the flow of an example of the flow of simultaneous charging mode.

Explanation of symbols

16 Generator (alternator)
18 Electric load 20 First battery (main battery)
22 Second battery (sub battery)
26 Switching means (charge relay)

Claims (2)

Automatic stop control means for stopping the engine when a predetermined idling stop condition is satisfied and restarting the engine when the predetermined restart condition is satisfied, and electric power to the electric load during the idling stop A battery charging device comprising: a first battery for supplying power; and a second battery for supplying power to the starter,
A generator that is constantly connected to the first battery and capable of changing a generated voltage;
Switching means for connecting or disconnecting the generator and the second battery;
Charge control means for controlling the generated voltage of the generator and the state of the switching means, and performing charge control for the first battery and the second battery;
Charging state detection means for detecting a charging state of the first battery and the second battery;
The charge control means includes
When the charging state detecting means detects that the first battery and the second battery are not fully charged, the switching means is connected, and the generated voltage of the generator is set to the Hi voltage. Set to charge the first battery and the second battery, then
It said charging state detection means, wherein when the second battery is detected that been fully charged before the said first battery, said switching means and the disconnected state, the first battery at Hi Voltage Only charge
It said charging state detection means, wherein when the first battery is detected that been fully charged earlier than the second battery is a power generation voltage of the generator is lowered by a predetermined value than the Hi voltage A battery charger for charging the second battery . The battery charger according to claim 1, wherein
The battery charging device, wherein a capacity of the second battery is set smaller than that of the first battery.

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