JP6237488B2 - Vehicle power supply - Google Patents

Description

  The present invention relates to a vehicle power supply device.

  In order to collect energy at the time of deceleration of the vehicle (regenerative function), a power supply device having a capacitor in addition to a normal auxiliary battery has become widespread. In such a power supply device, a DC / DC converter is provided between an alternator, an auxiliary battery, or the like and a capacitor in order to adjust the voltage.

In such a power supply device, when power is supplied to the starter for restarting the internal combustion engine stopped by idling stop, control using the power of the capacitor instead of the secondary battery may be performed.
Patent Document 1 describes a method for determining the internal resistance of a capacitor.

JP 2013-233011 A

  In the prior art, since constant idling stop control is used regardless of the internal resistance value of the capacitor, there is a possibility that restart from idling stop may not be possible if the internal resistance value of the capacitor increases.

  For example, when the internal resistance of the capacitor increases due to a decrease in capacitor temperature, capacitor deterioration, or the like, the voltage applied to the starter decreases, which may make it impossible to restart the internal combustion engine.

  The present invention has been made to solve such a problem, and provides a vehicle power supply device that can avoid an event that it is impossible to restart from an idling stop regardless of the internal resistance value of the capacitor. The purpose is to provide.

The power supply device for a vehicle according to the present invention is a power supply device for a vehicle, and includes a secondary battery, an auxiliary device and a DC / DC converter, a secondary battery and an auxiliary device connected in parallel to the secondary battery. In contrast, a capacitor connected via a DC / DC converter and a starter connected to the capacitor, the DC / DC converter includes an internal resistance value measuring means for measuring the internal resistance value of the capacitor, and a power source The device changes the control related to idling stop of the internal combustion engine that is started using a starter according to the internal resistance value of the capacitor, and when the internal resistance value exceeds the first threshold, the control is to prohibit the idling stop. When the internal resistance value exceeds the second threshold value and is less than the first threshold value, the voltage of the capacitor during idling stop is set to a predetermined lower limit voltage that can start the internal combustion engine. And control to a value above a predetermined lower limit voltage value, Ru value der internal resistance value represents the lower limit of the startup possible voltage value of the internal combustion engine when a first threshold value.

  According to such a configuration, the control related to the idling stop of the internal combustion engine is changed according to the internal resistance value of the capacitor.

Internal resistance value is less than the first threshold value exceeds a second threshold, and the voltage of the capacitor exceeds the lower limit voltage value, and can supply power to the auxiliary machine from both the secondary battery and the capacitor, and the secondary When electric power needs to be supplied from the battery or the capacitor to the auxiliary machine, the electric power may be supplied from the capacitor to the auxiliary machine.
The control for setting the voltage of the capacitor to be equal to or higher than the lower limit voltage value may include control for prohibiting the supply of power from the capacitor to the auxiliary machine when the voltage of the capacitor is equal to or lower than the lower limit voltage value.
The control for setting the voltage of the capacitor to be equal to or higher than the lower limit voltage value may include control for starting the internal combustion engine when the voltage of the capacitor becomes equal to or lower than the lower limit voltage value during idling stop .

  According to the vehicle power supply device of the present invention, the control related to the idling stop of the internal combustion engine is changed according to the internal resistance value of the capacitor, so that the restart from the idling stop can be performed regardless of the internal resistance value of the capacitor. It is possible to avoid the phenomenon of being impossible.

  For example, when the internal resistance increases to some extent, the idling stop itself is avoided by prohibiting the idling stop, so that it is also possible to avoid the event that the restart from the idling stop cannot be performed.

It is a figure which shows the structure containing the power supply device of the vehicle which concerns on Embodiment 1 of this invention. It is a figure explaining the measurement principle of the internal resistance value of the capacitor of FIG. It is a figure which shows the example of the control which concerns on the idling stop of an internal combustion engine changed according to the internal resistance value of the capacitor of FIG.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration including a power supply device 1 according to Embodiment 1 of the present invention.
The power supply device 1 is a power supply device for a vehicle and supplies power to a load mounted on the vehicle. The load is, for example, the auxiliary machine 2.

  The power supply device 1 includes an alternator 3, an auxiliary battery 4, a capacitor 5, a DC / DC converter 6, and a starter 7. The alternator 3 functions as a generator. The auxiliary battery 4 is a secondary battery, for example, a lead battery. The capacitor 5 is, for example, an electric double layer capacitor (EDLC).

  At least a part of the load (auxiliary machine 2 in the example of FIG. 1), the alternator 3, and the DC / DC converter 6 are connected in parallel to the auxiliary battery 4. Capacitor 5 is connected to auxiliary battery 4 and auxiliary machine 2 via DC / DC converter 6, and starter 7 is connected to capacitor 5 via starter activation switch 7a. In particular, in this embodiment, the capacitor 5 and the starter 7 are connected in parallel to the auxiliary machine 2, the alternator 3 and the auxiliary battery 4 via the DC / DC converter 6.

  Although the internal configuration of the DC / DC converter 6 is not particularly described, the DC / DC converter 6 has a function of converting the voltage of power supplied from at least one of the alternator 3 and the auxiliary battery 4 and supplying the voltage to the capacitor 5. . Further, the DC / DC converter 6 has a function of converting the voltage of the electric power supplied from the capacitor 5 and supplying it to at least one of the auxiliary machine 2, the alternator 3 and the auxiliary battery 4.

  In other words, a part of the load (auxiliary machine 2) is directly connected to the auxiliary battery 4, and is connected to the capacitor 5 via the DC / DC converter 6. For this reason, when the auxiliary machine 2 is supplied with power from the auxiliary battery 4, the voltage of the auxiliary battery 4 is applied as it is. On the other hand, when the auxiliary machine 2 is supplied with electric power from the capacitor 5, the voltage can be controlled via the DC / DC converter 6.

  The starter 7 receives power supplied from the capacitor 5 and starts an internal combustion engine (not shown).

  Although not particularly illustrated, the power supply device 1 includes a control device that controls the operation of the power supply device 1. The control device is constituted by, for example, a computer (for example, a microprocessor or the like) that includes a calculation unit and a storage unit. Although not specified below, the control of the alternator 3, the auxiliary battery 4, the capacitor 5, and the DC / DC converter 6 is executed by this control device. The computer controls only the DC / DC converter 6.

  Further, the DC / DC converter 6 includes internal resistance value measuring means for measuring the internal resistance value of the capacitor 5. The internal resistance value measuring means can be configured using, for example, a voltage measuring means 6a. Such internal resistance value measuring means measures the internal resistance value based on, for example, a change in voltage during charging due to a constant current.

FIG. 2 is a diagram for explaining an example of the principle of measuring the internal resistance value of the capacitor 5 by the internal resistance value measuring means configurable using the voltage measuring means.
First, the control device charges the capacitor 5 with a constant current (current value is I). The voltage V2 at time t1 after the elapse of the predetermined time T1 from the charging start time t0 is measured, and further the voltage V3 at time t2 after the elapse of the predetermined time T2 is measured. Thereafter, the slope a of the voltage from time t1 to t2 is calculated as a = (V3-V2) / (t2-t1). Thereafter, based on the slope a, the voltage V1 at time t0 + 0 immediately after the start of charging is calculated. For example, V1 = V2-a. (T1-t0). Thereafter, the internal resistance value R is calculated based on the voltage V1 and the voltage V0 at time t0-0 immediately before the start of charging. For example, R = (V1-V0) / I.

  The configuration of the internal resistance value measuring means and the internal resistance value measuring method can be realized using any other known technique. Further, information indicating the internal resistance value R (for example, a value of R or a value indicating a range to which R belongs) may be notified to the control device or the like.

Next, the operation of the power supply device 1 according to Embodiment 1 will be described.
When the vehicle is decelerated, the power supply device 1 generates power with the alternator 3. At least a part of the generated electric power charges the capacitor 5 after adjusting the voltage and current by the DC / DC converter 6.

  When the power supply device 1 charges the capacitor 5, the internal resistance value of the capacitor 5 is measured by the internal resistance value measuring unit. Then, the power supply device 1 changes the control related to the idling stop of the internal combustion engine according to the internal resistance value of the capacitor 5.

  FIG. 3 is a diagram illustrating an example of control related to idling stop of the internal combustion engine, which is changed according to the internal resistance value of the capacitor 5. In the example of FIG. 3, the content of the control is changed according to a threshold value related to the internal resistance value of the capacitor 5. In the example of FIG. 3, a first threshold value R1 and a second threshold value R2 are shown as two threshold values (where 0 <R2 <R1).

  As shown in FIG. 3, when the internal resistance value of the capacitor 5 exceeds the first threshold value R <b> 1, the power supply device 1 performs control to prohibit idling stop. For example, even if the internal combustion engine is idling for a long time, the internal combustion engine is not stopped. Here, if the internal resistance value becomes too large, the restart of the internal combustion engine may be impossible, but the value of the first threshold value R1 is set to a value belonging to a range in which the internal combustion engine can be restarted. If this is the case, the internal combustion engine will not stop in a state where the internal resistance has become so large that restarting is impossible.

  When the internal resistance value of the capacitor 5 exceeds the second threshold value R2 and is less than the first threshold value R1, control is performed so that the voltage of the capacitor 5 during idling stop is equal to or higher than a predetermined lower limit voltage value Vth. This Vth is the lower limit voltage value at which the internal combustion engine can be started, for example, when the internal resistance value is R1, and represents the lower limit of the voltage value at which the internal combustion engine can be started (or restarted). .

  The value of Vth does not have to be 10 V, and can be appropriately determined by a person skilled in the art so as to be suitable when the internal resistance value of the capacitor 5 exceeds the second threshold R2 and is less than the first threshold R1. Further, the value of Vth does not necessarily correspond to the actual lower limit voltage value at which the internal combustion engine can be started, and may be set including a certain margin value, for example.

The control for setting the voltage of the capacitor 5 during idling stop to Vth or more may be realized in any way, but for example, the following two specific controls are possible.
As the first specific control, when the voltage of the capacitor 5 is equal to or lower than Vth, it is possible to control to prohibit the supply of power from the capacitor 5 to the auxiliary machine 2. For example, when electric power is supplied from the capacitor 5 to the auxiliary machine 2 and the voltage of the capacitor 5 decreases with this, the time when the voltage of the capacitor 5 becomes Vth or less (or when it becomes equal to Vth) ), The DC / DC converter 6 is shut down, and the supply of power from the capacitor 5 to the auxiliary machine 2 is stopped. The supply of power to the auxiliary machine 2 immediately after that is performed from the auxiliary battery 4, for example. Even when the voltage of the capacitor 5 becomes equal to or lower than Vth, the capacitor 5 can be charged from the alternator 3 or the auxiliary battery 4 via the DC / DC converter 6.

  As described above, the voltage of the capacitor 5 during idling stop is maintained at Vth or higher (in practice, regardless of whether idling is stopped) by the first specific control. When the voltage of the capacitor 5 becomes less than Vth, it can be raised to Vth or more by charging the capacitor 5.

  The second specific control can be a control for starting the internal combustion engine when the voltage of the capacitor 5 becomes Vth or less during idling stop. For example, while the internal combustion engine is idling stopped, electric power is supplied from the capacitor 5 to the auxiliary machine 2 to decrease the voltage of the capacitor 5 and the voltage of the capacitor 5 becomes equal to or lower than Vth (or equal to Vth). At that time, electric power is supplied from the capacitor 5 to the starter 7 to start the internal combustion engine. The supply of power to the auxiliary machine 2 immediately after that is performed from the auxiliary battery 4, for example. Even when the voltage of the capacitor 5 becomes equal to or lower than Vth, the capacitor 5 can be charged from the alternator 3 or the auxiliary battery 4 via the DC / DC converter 6.

  In this way, the voltage of the capacitor 5 during idling stop is maintained at Vth or higher by the second specific control. When the voltage of the capacitor 5 becomes less than Vth, it can be raised to Vth or more by charging the capacitor 5.

  The first specific control and the second specific control may be combined. For example, when the voltage of the capacitor 5 becomes equal to or lower than Vth during idling stop, it is possible to prohibit the supply of electric power from the capacitor 5 to the auxiliary machine 2 and to start the internal combustion engine.

  By either the first specific control or the second specific control, the value of the second threshold value R2 is set so as to belong to a range in which the internal combustion engine can be restarted when the voltage of the capacitor 5 is Vth. If this is done, the internal combustion engine will not stop in a state where the voltage of the capacitor 5 is lowered so that restarting is impossible.

  In the case where the internal resistance value of the capacitor 5 exceeds the second threshold value R2 and is less than the first threshold value R1, and the voltage of the capacitor 5 exceeds Vth, the power supply device 1 has the capacitor 5 connected to the auxiliary battery. The power may be controlled to be supplied to the auxiliary machine 2 with priority over 4. In other words, the internal resistance value exceeds the second threshold R2 and is less than the first threshold R1, the voltage of the capacitor 5 exceeds Vth, and power can be supplied from both the auxiliary battery 4 and the capacitor 5 to the auxiliary machine 2 And when it is necessary to supply power from the auxiliary battery 4 or the capacitor 5 to the auxiliary machine 2 (for example, when the alternator 3 is not generating power), the auxiliary battery 4 supplies power to the auxiliary machine 2. The power may be supplied to the auxiliary machine 2 from the capacitor 5 without being supplied.

  As shown in FIG. 3, when the internal resistance value of the capacitor 5 is less than the second threshold value R2, the power supply device 1 performs normal control. For example, during normal driving (for example, when the vehicle is not accelerating or decelerating), the alternator 3 is stopped and the electric charge stored in the capacitor 5 is adjusted after the voltage is adjusted via the DC / DC converter 6. To the machine 2 and the auxiliary battery 4. Further, as the normal control, any known capacitor control in the vehicle power supply device may be included. If the value of the second threshold value R2 is set to a value belonging to a range in which the internal combustion engine can be restarted regardless of the voltage of the capacitor 5, the internal combustion engine can always be restarted.

  As described above, by changing the control as shown in FIG. 3, it is possible to avoid the event that the restart from the idling stop cannot be performed regardless of the internal resistance value of the capacitor 5.

In the first embodiment, the following modifications can be made.
The internal resistance value measuring means may measure the internal resistance value of the capacitor 5 based on a change in voltage during charging instead of charging.

  In the first embodiment, the control is changed based on the two threshold values R1 and R2, but either threshold value may be used. For example, the threshold value may be only the second threshold value R2, normal control may be performed when the internal resistance value is less than R2, and idling stop may be prohibited when the internal resistance value exceeds R2.

  Three or more threshold values may be provided. Further, the value of the lower limit voltage value at which the internal combustion engine can be started may be changed stepwise in the interval between the threshold values. In addition, the lower limit voltage value Vth is the lower limit of the voltage value at which the internal combustion engine can be started (or restarted) when the internal resistance value is R1, but the internal combustion engine start (or The lower limit of the voltage value that can be restarted) may be set to the lower limit voltage value Vth and the voltage of the capacitor 5 may be controlled to be equal to or higher than Vth.

  DESCRIPTION OF SYMBOLS 1 Power supply device, 4 Auxiliary battery (secondary battery), 5 Capacitor, 6 DC / DC converter, 6a Voltage measurement means (internal resistance value measurement means), 7 Starter, R Internal resistance value, R1 1st threshold value, R2 1st 2 threshold.

Claims (4)

A power supply device for a vehicle,
A secondary battery,
An auxiliary machine and a DC / DC converter connected in parallel to the secondary battery;
A capacitor connected to the secondary battery and the auxiliary machine via the DC / DC converter;
A starter connected to the capacitor,
The DC / DC converter includes an internal resistance value measuring means for measuring an internal resistance value of the capacitor,
The power supply device changes the control relating to the idling stop of the internal combustion engine started using the starter according to the internal resistance value of the capacitor,
When the internal resistance value exceeds the first threshold value, control to prohibit idling stop,
If the internal resistance value is less than the second threshold exceeds the first threshold value, the voltage of the capacitor in the idling stop, and control to the start of the internal combustion engine is a predetermined lower limit voltage value or possible ,
The predetermined lower limit voltage value is a value representing a lower limit of a voltage value at which the internal combustion engine can be started when the internal resistance value is the first threshold value.
Vehicle power supply. The internal resistance value exceeds the second threshold and is less than the first threshold;
The voltage of the capacitor exceeds the lower limit voltage value,
When it is possible to supply power to the auxiliary machine from both the secondary battery and the capacitor, and when it is necessary to supply power to the auxiliary machine from the secondary battery or the capacitor, the auxiliary machine can supply the auxiliary machine. machine supplies power to the power supply apparatus for a vehicle according to claim 1. The control for setting the voltage of the capacitor to be equal to or higher than the lower limit voltage value includes control for prohibiting power supply from the capacitor to the auxiliary device when the voltage of the capacitor is equal to or lower than the lower limit voltage value. The power supply device for a vehicle according to 1 or 2 . The control to the voltage of the capacitor the lower limit voltage value or more, comprising a control voltage of the capacitor during idling stop start the internal combustion engine when it becomes less than the lower limit voltage value, claim 1-3 The power supply device for a vehicle according to any one of the above.

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