JP6123777B2 - Automatic engine stop control device - Google Patents

Description

  The present invention relates to an engine automatic stop control device that controls idle stop of an engine for driving a vehicle.

  2. Description of the Related Art In recent years, vehicles equipped with a storage battery made of an electric double layer capacitor, a lithium ion secondary battery or the like apart from a lead battery are known. In such a vehicle, during the engine operation, the power demand is covered by the storage battery, and the lead battery hardly discharges the power. Therefore, during idle stop, assuming that discharge of power from the lead battery is allowed, the condition of the remaining capacity of the storage battery is eliminated from the idle stop condition, and if the lead battery is above the lower limit voltage, the idle stop is permitted. A technique has been proposed.

  Patent Document 1 discloses a technique for prohibiting an idle stop when the in-vehicle battery is deteriorated to some extent.

JP 2010-116044 A

  By the way, the usage mode of a vehicle changes with users who get on. For example, in a vehicle that mainly travels in an urban area where there are many signals, since the travel and stop are frequently performed, a sufficient deceleration period cannot be secured. Therefore, in such a vehicle, if the condition of the remaining capacity of the storage battery is removed from the idle stop condition, the engine is idle-stopped despite the insufficient charging of the storage battery using the deceleration period. In this case, the power demand during idle stop and return from idle stop is covered by the lead battery, and the life of the lead battery is shortened.

  On the other hand, in a vehicle that mainly travels in a suburb with few traffic lights, traveling and stopping are not performed as frequently as in an urban area, so a sufficient deceleration period can be secured. Therefore, in such a vehicle, even if the condition of the remaining capacity of the storage battery is eliminated from the idle stop condition, the engine is idle-stopped after the storage battery is sufficiently charged using the deceleration period. As a result, power demand during idle stop and return from idle stop is covered by the storage battery, and the life of the lead battery is extended.

  As described above, if the condition of the remaining capacity of the storage battery is eliminated from the idle stop condition, a difference in the life of the lead battery occurs depending on the usage mode of the vehicle, which gives an unfair feeling to the user.

  In addition, since the patent document 1 is not provided with a storage battery other than the vehicle-mounted battery, the premise is different from the present invention. Moreover, in patent document 1, the countermeasure for suppressing deterioration of a vehicle-mounted battery is not taken at all.

  An object of the present invention is to provide an automatic engine stop control device that can suppress the difference in the life of lead batteries between vehicles regardless of the usage mode of the vehicles.

An engine automatic stop control device according to an aspect of the present invention includes:
An engine automatic stop control device for controlling idle stop of an engine for driving a vehicle,
Lead battery,
A storage battery having a faster charge / discharge rate than the lead battery;
The power in at least one of the lead battery and the storage battery is used to restart the engine in an idle stop state, and is driven by the engine at least when the vehicle is decelerated to generate power. The lead battery and the storage battery Generator with motor function to charge
A current detection unit for detecting a current flowing in the lead battery;
An integration unit that calculates the charge / discharge amount integrated value by integrating the charge current value and the discharge current value of the lead battery detected by the current detection unit;
When the calculated charge / discharge amount integrated value is equal to or less than a first threshold indicating that the amount of use of the lead battery is high with respect to the number of idle stops, the idle stop is permitted regardless of the remaining capacity of the storage battery. The charging / discharging integrated value is larger than the first threshold value, and if the remaining capacity of the storage battery is larger than a predetermined second threshold value, an idle stop control unit that permits the idle stop is provided.

  According to this aspect, for the vehicle in which the charge / discharge amount integrated value of the lead battery is equal to or less than the first threshold and the use amount of the lead battery is not higher than the number of idle stops, the idle stop is performed regardless of the remaining capacity of the storage battery. Is allowed. Such a vehicle corresponds to a vehicle that can secure a sufficient deceleration period, is idle-stopped in a state in which the storage battery is sufficiently charged, and has almost no electric power discharged from the lead battery during the idle-stop and return from the idle-stop. . Therefore, such a vehicle is allowed to positively discharge electric power from the lead battery during idle stop and when returning from idle stop.

  On the other hand, for a vehicle in which the accumulated charge / discharge amount of the lead battery is greater than the first threshold and the amount of use of the lead battery is high with respect to the number of idle stops, the idle stop is not performed unless the remaining capacity of the storage battery is equal to or greater than the second threshold. Not allowed. Such a vehicle is a vehicle in which the deceleration period cannot be secured sufficiently, the vehicle is idle-stopped in a state where the storage battery is not sufficiently charged, and the electric power is discharged from the lead battery during the idle-stop and when returning from the idle-stop. To do. Therefore, for such a vehicle, since idle stop is prohibited, deterioration of the lead battery is suppressed.

  Therefore, this aspect can suppress the time difference until the lead battery reaches the end of its life between the vehicle that can sufficiently secure the deceleration period and the vehicle that cannot secure the deceleration period.

In the above aspect,
The idle stop control unit may increase the first threshold as the number of idle stops increases.

  According to this aspect, since the first threshold value increases as the number of idle stops increases, a vehicle with a higher battery usage with respect to the number of idle stops is less likely to be idle stopped, and deterioration of the lead battery is suppressed. Even in a vehicle where the amount of use of the lead battery is not high with respect to the number of idle stops, the lead battery deteriorates over time. In this aspect, since the first threshold value is increased as the number of idle stops increases, such a vehicle is idle stopped without considering the remaining capacity of the storage battery until the lead battery reaches the end of its life. . As a result, the number of idle stops can be increased for such vehicles.

In the above aspect,
The idle stop control unit may increase the second threshold as the calculated charge / discharge amount integrated value increases.

  According to this aspect, since the second threshold value increases as the charge / discharge amount integrated value increases, a vehicle with a high usage amount of the lead battery with respect to the number of idling stops is set to the idling stop as the deterioration of the lead battery proceeds. It becomes difficult to suppress the deterioration of the lead battery.

In the above aspect,
In the case where the calculated charge / discharge amount integrated value is not less than the first threshold value and the remaining capacity of the storage battery is not more than the second threshold value, the idle stop control unit determines that the remaining capacity is the second threshold value. The engine may be idle-stopped after the storage battery is forcibly charged by the generator with motor function until.

  According to this aspect, a vehicle having a high usage amount of the lead battery with respect to the number of idle stops is idled after the remaining capacity of the storage battery is forcibly set to the second threshold value by forced charging. Therefore, this aspect can be idle-stopped without putting a burden on a lead battery with respect to such a vehicle.

In the above aspect,
The idle stop control unit may perform the forced charging by causing the generator with a motor function to generate power even when the vehicle is accelerated.

  According to this aspect, since the generator with a motor function is generated not only when the vehicle is decelerated but also when accelerating, the remaining capacity of the storage battery can be set to the second threshold value in a short time.

In the above aspect,
The idle stop control unit may detect a degree of deterioration of the storage battery, and increase the second threshold as the detected degree of deterioration increases.

  As the capacitor degrades, the discharge rate increases. According to this aspect, since the second threshold value increases as the degree of deterioration of the storage battery increases, it is possible to avoid a situation where the power of the storage battery is insufficient during idle stop and the lead battery is used.

  ADVANTAGE OF THE INVENTION According to this invention, the time difference until the lead battery becomes a lifetime between the vehicle which could fully ensure the deceleration period, and the vehicle which could not be ensured can be suppressed.

1 is a circuit diagram showing an electrical configuration of a vehicle equipped with an engine automatic stop control device according to an embodiment of the present invention. It is a block diagram which shows the control system of the automatic stop control apparatus of the engine of this Embodiment. It is a graph which shows the characteristic of a 1st threshold value, a vertical axis | shaft shows the charging / discharging amount integrated value (Ah), and the horizontal axis has shown the frequency | count of IS. It is a flowchart which shows the process of the automatic stop control apparatus of the engine in this Embodiment. It is a graph which shows the characteristic of a 2nd threshold value, the vertical axis | shaft shows the 2nd threshold value and the horizontal axis has shown the charging / discharging amount integrated value. It is a graph which shows a correction characteristic, A vertical axis | shaft has shown the correction value and the horizontal axis has shown the deterioration degree.

(1) Overall Configuration of Vehicle FIG. 1 is a circuit diagram showing an electrical configuration of a vehicle equipped with an engine automatic stop control device according to an embodiment of the present invention. In the present embodiment, for example, a four-wheeled vehicle can be used as the vehicle. The vehicle shown in the figure includes an engine 1, a belt drive starter (hereinafter referred to as B-ISG2), a battery 3, a capacitor 4, a step-down circuit 5, an electric load 6, a gear drive starter 7 (Sta), The transmission 8 includes a differential 9, a wheel 10, a wheel shaft 11, a cooperative brake 12, a bypass relay 13, a voltage sensor 14, a current sensor 15, a capacitor relay 16, and a voltage sensor 17.

  B-ISG2 and capacitor 4 are electrically connected via line L1. The step-down circuit 5 is provided on a line L <b> 2 that connects the connection point K <b> 1 with the capacitor 4 and the electric load 6. The bypass relay 13 is provided on the line L3 connected in parallel with the step-down circuit 5. The battery 3 is electrically connected to the electric load 6 and the gear-driven starter 7 via a connection point K2 on the output side of the step-down circuit 5, and the negative electrode is grounded. The voltage sensor 14 is electrically connected to the connection point K2. A current sensor 15 is electrically connected to the negative electrode of the battery 3. A capacitor relay 16 is provided on the path L1. A voltage sensor 17 is electrically connected between the capacitor 4 and the capacitor relay 16.

  The engine 1 is provided in the engine room of the vehicle and runs the vehicle. As the engine 1, for example, a reciprocating engine or a diesel engine can be adopted.

  A B-ISG (belt-driven integrated starter generator) 2 restarts the engine 1 in an idle stop (hereinafter referred to as “IS”) state using electric power from at least one of the capacitor 4 and the battery 3. In addition, power is generated from the engine 1 at least when the vehicle is decelerated, and electric power is supplied to the capacitor 4, the battery 3, and the electric load 6. Here, when restarting the engine 1, the B-ISG 2 mainly uses power from the capacitor 4, and uses power from the battery 3 when the remaining capacity of the capacitor 4 is low.

  Specifically, the B-ISG 2 includes a motor generator 21, a rotor pulley 22 coupled to the rotor shaft of the motor generator 21, a crank pulley 23 coupled to the crankshaft of the engine 1, and the rotor pulley 22 and the crank pulley 23. And a wound belt 24. Here, the B-ISG 2 supplies power to the engine 1 via the crankshaft when the engine 1 is restarted.

  The B-ISG 2 generates power by rotating a rotor included in the motor generator 21 that rotates in conjunction with the crankshaft of the engine 1 in a magnetic field, and according to the increase or decrease of the current to the field coil that generates the magnetic field. Adjust the generated current. The B-ISG 2 includes a rectifier (not shown) that converts the generated AC power into DC power. That is, the electric power generated by the B-ISG 2 is converted to direct current by the rectifier and then transmitted to the capacitor 4, the battery 3, and the electric load 6.

  The battery 3 is a lead battery and is electrically connected to the B-ISG 2 and stores electric power generated by the B-ISG 2. Lead batteries store electrical energy by chemical reaction and are not suitable for rapid charge and discharge. However, the lead storage battery has a characteristic that it can store a relatively large amount of power because it easily secures a charging capacity.

  The capacitor 4 is, for example, an electric double layer capacitor, and is electrically connected to the B-ISG 2 and stores electric power generated by the B-ISG 2. Unlike a lead storage battery, an electric double layer capacitor stores electricity by physical adsorption of electrolyte ions. For this reason, the electric double layer capacitor has the characteristics that it can be charged / discharged relatively quickly and the internal resistance is small.

  The step-down circuit 5 is composed of, for example, a DCDC converter, and steps down the voltage supplied from the B-ISG 2 and the capacitor 4 to a predetermined voltage and supplies the voltage to the electric load 6.

  The electrical load 6 is composed of one or more electrical components that are driven by a predetermined voltage output from the step-down circuit 5. In the present embodiment, for example, an EPAS (electric power steering mechanism), an air conditioner, an audio, and a glow path are employed as the electric load 6, but these are examples.

  The gear driven starter 7 is driven when the engine 1 is started to crank the engine 1. Here, the gear-driven starter 7 includes a starter motor 71, a pinion 72, and the like, and the pinion 72 transmits the power of the starter motor 71 to the ring gear 111 provided in the engine 1 to crank the engine 1. In the present embodiment, the gear driven starter 7 cranks the engine 1 mainly when the engine 1 is started by turning on the ignition key.

  The transmission 8 is configured by, for example, a manual transmission, an automatic transmission, or a CVT, and changes the rotational speed of the engine 1 to a rotational speed suitable for traveling. The differential 9 automatically increases the driving force of the outer wheel by the resistance of the inner wheel caused by the curve so that the vehicle can smoothly bend the curve. The wheel shaft 11 transmits the power of the engine 1 to the wheel 10 via the transmission 8 and the differential 9. The cooperative brake 12 cooperatively controls the regenerative brake and the hydraulic brake according to the operation amount of the foot brake pedal 121.

  The voltage sensor 14 measures the voltage of the battery 3. The current sensor 15 measures the current flowing through the battery 3. The capacitor relay 16 is turned off when the capacitor 4 is disconnected from the circuit, and is turned on when the capacitor relay 16 is incorporated in the circuit. The voltage sensor 17 measures the voltage of the capacitor 4.

  The operation of the vehicle shown in FIG. 1 will be briefly described. First, when the ignition key is turned on, the gear-driven starter 7 is driven by the power from the battery 3 to crank the engine 1 and the engine 1 is started.

  At the time of deceleration of the vehicle, the B-ISG 2 generates power with the power from the engine 1. The electric power generated by the B-ISG 2 is stored in the capacitor 4. The power generated by the B-ISG 2 is stepped down by the step-down circuit 5 and supplied to the electric load 6, and the surplus power is charged to the battery 3.

  When a predetermined IS condition that the vehicle stops is satisfied, the engine 1 is shifted to the IS state. On the other hand, when a predetermined IR (idle stop restart) condition is established in the IS state, the B-ISG 2 is driven by the electric power from the capacitor 4 to restart the engine 1. Further, when the power demand of the electric load 6 is high and the current flowing through the line L2 exceeds a predetermined value, the bypass relay 13 is turned on, and the line L3 becomes a bypass path of the step-down circuit 5. Thereby, the electric power of the capacitor 4 and the B-ISG 2 is not stepped down by the step-down circuit 5 and is supplied to the electric load 6 through the line L3. As a result, the driving of the electric load 6 can be continued.

  Further, when the power of the battery 3 is insufficient during restart from the IS, the PCM 210 shown in FIG. 2 turns on the bypass relay 13 to supply the power of the battery 3 to the B-ISG 2.

  The capacitor 4 is an example of a storage battery, the B-ISG 2 is an example of a generator with a motor function, and the current sensor 15 is an example of a current detection unit. In the present embodiment, the capacitor 4 is employed as the storage battery. However, this is merely an example, and any storage battery may be employed as long as the storage battery has a faster charge / discharge rate than the battery 3. For example, a lithium secondary battery may be employed as the storage battery.

(2) Control System FIG. 2 is a block diagram showing a control system of the engine automatic stop control device of the present embodiment. As shown in the figure, an automatic engine stop control device includes a power train control module (PCM) 210, an accelerator SW (abbreviation of switch, the same applies hereinafter) 201, a foot brake SW 202, a vehicle speed sensor 203, a current sensor 15, a voltage. The sensor 14, the voltage sensor 17, the B-ISG 2, the gear drive starter 7, and the injector 206 are provided. The PCM 210 is electrically connected to each component shown in the block of FIG. 2 such as the accelerator SW 201 and the foot brake SW 202 via various signal lines.

  The accelerator SW 201 detects that the accelerator pedal is turned on by operating the accelerator pedal, and outputs a detection signal indicating the accelerator pedal ON and the amount of operation of the accelerator pedal to the PCM 210.

  The foot brake SW 202 detects that the foot brake pedal 121 is turned on by the operation of the foot brake pedal 121 (see FIG. 1), and sends a detection signal indicating the ON of the foot brake pedal 121 and the operation amount of the foot brake pedal 121 to the PCM 210. Output to.

  The vehicle speed sensor 203 detects the traveling speed of the vehicle and outputs a detection signal indicating the detected speed to the PCM 210.

  The current sensor 15 measures both the discharge current and the charge current flowing through the battery 3 and outputs them to the PCM 210. The voltage sensor 14 measures the voltage of the battery 3 and outputs it to the PCM 210 as described with reference to FIG. The voltage sensor 17 measures the voltage of the capacitor 4 and outputs it to the PCM 210.

  The B-ISG 2 and the gear drive starter 7 are the same as those described with reference to FIG. 1 and are driven under the control of the PCM 210. The injector 206 injects fuel into the engine 1 under the control of the PCM 210.

  The PCM 210 is constituted by, for example, a microcomputer including a CPU, a ROM, a RAM, and the like, or a dedicated hardware circuit, and controls the entire control system of the vehicle. In the present embodiment, the PCM 210 includes functional blocks of an integration unit 211, an IS control unit 212, an IS flag storage unit 213, an IS number storage unit 214, and an integration value storage unit 215. These functional blocks may be realized, for example, by the CPU executing a control program stored in the ROM, or may be realized by a dedicated hardware circuit.

  The integration unit 211 calculates the charge / discharge amount integrated value by integrating the charge current value and the discharge current value of the battery 3 detected by the current sensor 15. Here, the charge / discharge amount integrated value is the sum of the integrated value of the discharge current and the integrated value of the charge current from the start of use of the battery 3 to the present time. That is, the deterioration of the battery 3 depends on the usage amount such as how many amperes of current are charged and discharged. Therefore, the integrating unit 211 calculates an integrated charge / discharge amount value in order to estimate the deterioration of the battery 3. The calculated charge / discharge amount integrated value is stored in the integrated value storage unit 215.

  When the charge / discharge amount integrated value calculated by the integration unit 211 is equal to or less than the first threshold value indicating that the usage amount of the battery 3 is high with respect to the number of ISs, the IS control unit 212 is independent of the remaining capacity of the capacitor 4. IS is permitted, and if the charge / discharge amount integrated value is larger than the first threshold value, the IS is permitted if the remaining capacity of the capacitor 4 is larger than a predetermined second threshold value.

  A vehicle with a lot of driving in an urban area has a lot of low-speed driving, so that a sufficient deceleration period cannot be secured, and the engine 1 is brought into the IS state even though the remaining capacity of the capacitor 4 is low. In this case, the battery 3 covers the power demand during the IS and when returning from the IS state. Therefore, in such a vehicle, if the engine 1 is set to the IS state regardless of the remaining capacity of the capacitor 4, the electric power discharged from the battery 3 further increases, and the deterioration of the battery 3 is promoted.

  On the other hand, since a vehicle that frequently travels in the suburbs and the countryside can secure a sufficient deceleration period, the engine 1 is brought into the IS state after the capacitor 4 is sufficiently charged. In this case, the power demand during IS and return from the IS state is mainly covered by the capacitor 4. Therefore, in such a vehicle, the electric power discharged from the battery 3 does not increase, and deterioration of the battery 3 is suppressed.

  In this way, regardless of the remaining capacity of the capacitor 4, if the mode in which the engine 1 is shifted to the IS state is adopted, the vehicle traveling in the urban area has a longer life of the battery 3 than the vehicle traveling in the suburbs or the countryside. It gives an unfair feeling to both users. Therefore, in this embodiment, the IS control unit 212 adopts the above-described configuration to solve such a problem.

  FIG. 3 is a graph showing the characteristics of the first threshold, where the vertical axis indicates the charge / discharge amount integrated value (Ah), and the horizontal axis indicates the number of ISs. A straight line G30 indicates the first threshold value. The straight line G30 has a characteristic of increasing linearly as the number of IS increases. The upper region across the straight line G30 is a capacitor condition required region, and the lower region is a capacitor condition unnecessary region. The capacitor condition required region is a region where the capacitor condition is imposed when the engine 1 is set to the IS state. The capacitor condition unnecessary region is a region where no capacitor condition is imposed when the engine 1 is set to the IS state. The capacitor condition is a condition that the remaining capacity of the capacitor 4 is larger than the second threshold value.

  A vehicle in which the usage mode of the battery 3 belongs to the capacitor condition required region is a vehicle in which the usage amount of the battery 3 is large with respect to the number of ISs and sufficient electric power cannot be accumulated in the capacitor 4 during deceleration. Therefore, the vehicle condition in which the usage mode of the battery 3 belongs to the capacitor condition necessary region is imposed a capacitor condition when the engine 1 is set to the IS state. Therefore, in this vehicle, if the remaining capacity of the capacitor 4 is less than or equal to the second threshold and the remaining capacity of the capacitor 4 is insufficient, the engine 1 is not brought into the IS state. Thereby, deterioration of the battery 3 is suppressed.

  For example, the point P2 represents a point where the IS number is X2 times and the charge / discharge amount integrated value is E2. On the other hand, the first threshold value corresponding to the IS number of times X2 is E0 (X2). For this reason, the charge / discharge amount integrated value E2 is larger than the first threshold value E0 (X2), and the point P2 belongs to the capacitor condition necessary region. Therefore, the capacitor condition is imposed on the vehicle whose usage mode of the battery 3 is the point P2 at the time of IS transition.

  Even in such a vehicle, the deceleration period may be sufficiently secured. In this case, since sufficient electric power is stored in the capacitor 4, it is preferable to set the engine 1 to the IS state. Therefore, in the present embodiment, even if the usage mode of battery 3 is a vehicle belonging to the capacitor condition required region, if the remaining capacity of capacitor 4 is larger than the second threshold, engine 1 is set to the IS state. Thereby, the fuel consumption improvement of the engine 1 can be aimed at.

  Here, as the second threshold value, for example, the remaining IS of the capacitor 4 that can return the engine 1 from the IS state even if the engine 1 is brought into the IS state for the IS time required to be secured at least. Capacity can be adopted.

  A vehicle in which the usage mode of the battery 3 belongs to the capacitor condition unnecessary region is a vehicle in which the usage amount of the battery 3 is low with respect to the IS number and sufficient electric power is accumulated in the capacitor 4 during deceleration. In such a vehicle, since the deterioration of the battery 3 has not progressed, from the viewpoint of positively allowing the use of the battery 3 during IS even if sufficient power cannot be secured in the capacitor 4 during deceleration. It is preferable to discharge power from the battery 3. Therefore, in the present embodiment, in the vehicle in which the usage mode of the battery 3 belongs to the capacitor condition unnecessary region, the engine 1 is set to the IS state without imposing the capacitor condition. Thereby, since use of the battery 3 is permitted during IS, the situation where only the capacitor 4 is used and the battery 3 is hardly used can be avoided.

  For example, the point P1 represents a point where the IS count is X1 and the charge / discharge amount integrated value is E1. On the other hand, the first threshold value corresponding to the number of IS times X1 is E0 (X1). For this reason, the charge / discharge amount integrated value E1 is equal to or less than the first threshold value E0 (X1), and the point P1 belongs to the capacitor condition unnecessary region. Therefore, the vehicle whose usage mode of the battery 3 is the point P2 is not subjected to the capacitor condition at the time of IS transition.

  Returning to FIG. 2, the IS control unit 212 permits IS by setting the IS flag stored in the IS flag storage unit 213 to a value (for example, 0) indicating permission of IS. On the other hand, the IS control unit 212 may prohibit the IS by setting the IS flag to a value (for example, 1) indicating that the IS is prohibited. When the IS flag is set to 0, the vehicle is set to the IS permission state, and the engine 1 is set to the IS state when a predetermined IS condition is established such that the vehicle stops. On the other hand, when the IS flag is set to 1, the vehicle is set to the IS prohibited state, and the engine 1 is not set to the IS state even if the IS condition is satisfied.

  Further, the IS control unit 212 manages the number of ISs executed from the start of use of the engine 1 to the present time. For example, every time the engine 1 is brought into the IS state once, the IS control unit 212 increments the IS number stored in the IS number storage unit 214 by one.

  The IS flag storage unit 213 stores the IS flag managed by the IS control unit 212. The IS count storage unit 214 stores the IS count managed by the IS control unit 212. The integrated value storage unit 215 stores the charge / discharge amount integrated value calculated by the integrating unit 211.

  FIG. 4 is a flowchart showing the process of the engine automatic stop control apparatus according to the present embodiment. This flowchart is executed periodically after the ignition key of the vehicle is turned on, for example. First, in S301, the PCM 210 reads detection signals from the accelerator SW 201, the foot brake SW 202, and the vehicle speed sensor 203, and at the same time, the capacitor voltage from the voltage sensor 17 (Capa), the battery voltage from the voltage sensor 14 (Bat), and the current sensor 15. Read battery current from.

  Next, the integration unit 211 calculates the current charge / discharge amount integrated value E by adding the battery current read in S301 to the charge / discharge amount integrated value stored in the integrated value storage unit 215 (S302).

  Next, the IS control unit 212 calculates the remaining capacity Q of the capacitor 4 using the capacitor voltage read in S301 (S303). Here, the remaining capacity Q is calculated by Q = CV, for example, where C is the capacitance of the capacitor 4 and V is the capacitor voltage read in S301.

  Next, the IS control unit 212 sets a first threshold value E (X) corresponding to the current IS number X (S304). Here, the IS control unit 212 stores in advance the straight line G30 shown in FIG. 3, and the first threshold value E (X) corresponding to the current IS number X may be set using the straight line G30.

  Next, the IS control unit 212 determines whether or not the charge / discharge amount integrated value E calculated in S304 is larger than the first threshold value E (X) (S305). If charge / discharge amount integrated value E> first threshold value E (X) (Y in S305), IS control unit 212 determines that it is necessary to impose a capacitor condition, and remaining capacity Q calculated in S303 is the second threshold value. If larger than Q0 (S306Y), it is determined that the capacitor condition is satisfied, and the process proceeds to S308.

  On the other hand, if the charge / discharge amount integrated value E is equal to or less than the first threshold value E (X) in S305 (N in S305), the IS control unit 212 determines that it is not necessary to impose a capacitor condition, and the process proceeds to S308. .

  In S306, if the remaining capacity Q is equal to or less than the second threshold value Q0 (N in S306), the IS control unit 212 determines that the capacitor condition is not satisfied, and advances the process to S307.

  In S307, the IS control unit 212 forcibly charges the capacitor 4 (S307), and returns the process to S306. That is, by repeating the loop of S306 and S307, the capacitor 4 is forcibly charged until it reaches the second threshold value Q0.

  Here, the IS control unit 212 may force-charge the capacitor 4 by causing the B-ISG 2 to generate power not only when the vehicle decelerates but also when the vehicle accelerates. Specifically, when the vehicle is decelerating and accelerating, the IS control unit 212 may forcibly charge the capacitor 4 by passing a current through the field coil of the B-ISG 2. When the B-ISG 2 is generated during acceleration, it is normally prohibited because it generates power using fuel. However, in the present embodiment, the B-ISG 2 generates power even during acceleration. As a result, the capacitor 4 is quickly charged until the remaining capacity Q reaches the second threshold value Q0. In addition, the time of acceleration refers to a state where the accelerator pedal is depressed and fuel is supplied to the engine 1, for example.

  In S308, the IS control unit 212 determines whether or not the IS condition is satisfied. Here, the IS condition is established when all the following conditions (i) to (iv) are satisfied.

(I) When accelerator SW 201 outputs a detection signal indicating OFF (ii) When foot brake SW 202 outputs a detection signal indicating ON (iii) When vehicle traveling speed (vehicle speed) is smaller than threshold TH1 (iv) When the voltage (battery voltage) of the battery 3 measured by the voltage sensor 14 is larger than the threshold value TH2, the conditions (i) and (ii) take into account that the vehicle has entered a deceleration state. The condition (iii) takes into consideration that the vehicle speed of the vehicle that has entered the deceleration state has become low enough to allow the engine 1 to be in the IS state. Therefore, as the threshold value TH1, an empirically obtained vehicle speed that does not hinder the running of the vehicle even when the engine 1 is shifted to the IS state can be employed. The condition (iv) considers whether or not the battery 3 stores electric power that can restart the engine 1. Therefore, the threshold value TH2 is the lower limit value of the remaining capacity of the battery 3 at which the gear-driven starter 7 can restart the engine 1 even if the engine 1 fails to restart using B-ISG2. Empirically obtained values can be used.

  In S308, when the IS condition is satisfied (Y in S308), the IS control unit 212 executes IS and sets the engine 1 to the IS state. On the other hand, if the IS condition is not satisfied (N in S308), the process returns to S301, and the processes after S301 are executed again. In S309, the IS control unit 212 increments the number of ISs by one.

  As described above, according to the present embodiment, since the deceleration time cannot be sufficiently secured, the remaining capacity of the capacitor 4 is less than the second threshold value for the vehicle in which the usage amount of the battery 3 is high with respect to the IS number. If not, IS is not allowed. On the other hand, for vehicles in which the deceleration time is sufficiently secured and the usage amount of the battery 3 is not high with respect to the number of ISs, the discharge of power from the battery 3 is unconditionally during the IS and when returning from the IS. Is allowed.

  Therefore, it is possible to suppress a time difference until the battery 3 reaches the end of its service life between the vehicle that has sufficiently secured the deceleration time and the vehicle that has not been able to ensure the deceleration time.

  It should be noted that this embodiment can employ the following modifications.

(1) Modification 1
In the above embodiment, the second threshold value Q0 has been described as a fixed value. In the first modification, the second threshold value Q0 is increased as the charge / discharge amount integrated value increases.

  FIG. 5 is a graph showing the characteristics of the second threshold value Q0. The vertical axis represents the remaining capacity of the capacitor 4, and the horizontal axis represents the charge / discharge amount integrated value. A straight line G50 indicates the second threshold value Q0. The straight line G50 has a characteristic of increasing linearly as the charge / discharge amount integrated value increases. As the second threshold value Q0 is larger, the capacitor condition becomes stricter and the engine 1 is less likely to be in the IS state. Further, as the charge / discharge amount integrated value increases, the deterioration of the battery 3 progresses. Further, just because the capacitor condition is satisfied, not all the electric power is supplied by the capacitor 4 during the IS and when returning from the IS. For example, if the power demand of electrical components such as an air conditioner is high, the power of the battery 3 is used. Therefore, refraining from executing IS is effective in suppressing deterioration of the battery 3. Therefore, in Modification 1, as the charge / discharge amount integrated value increases, the second threshold value is increased to make the capacitor condition stricter. Thereby, deterioration of a battery can be suppressed.

  In order to realize this, the IS control unit 212 stores in advance the characteristics of the second threshold value Q0 indicated by the straight line G50. Then, in S306, the IS control unit 212 specifies the second threshold value Q0 corresponding to the current charge / discharge amount integrated value from the stored characteristics of the second threshold value Q0, and sets the specified second threshold value Q0 as the remaining capacity Q. Compare.

(2) Modification 2
In the above embodiment, the deterioration of the capacitor 4 is not taken into consideration. In the second modification, the second threshold value Q0 is increased as the capacitor 4 deteriorates.

  As the capacitor 4 deteriorates, the discharge rate increases. For this reason, the capacitor 4 that has deteriorated has a lower rate of decrease in the remaining capacity than the capacitor 4 that has not deteriorated. Therefore, when the second threshold value Q0 is set without taking the deterioration of the capacitor 4 into consideration, when the engine 1 is brought into the IS state using the same capacitor condition as that of the capacitor 4 that has not deteriorated, the capacitor 4 having deteriorated has progressed. The power of the battery 3 is used due to the shortage of the power of the capacitor 4, and there is a possibility that the deterioration of the battery 3 is promoted. Therefore, in the second modification, the above-described aspect is adopted to suppress the deterioration of the capacitor 4.

  In this case, the deterioration of the capacitor 4 may be detected as follows. First, the IS control unit 212 turns off the capacitor relay 16 and turns on the switching element 41, monitors the capacitor voltage with the voltage sensor 17, and resists the power of the capacitor 4 until the capacitor voltage drops from the voltage V1 to the voltage V2. A discharge time is measured via R, and a decrease time from the voltage V1 to the voltage V2 is measured. The voltages V1 and V2 are fixed values, and V1> V2. Then, the IS control unit 212 calculates, for example, the reciprocal of this decrease time as the degree of deterioration of the capacitor 4. In addition, the IS control unit 212 stores in advance correction characteristics in which the degree of deterioration is associated with the correction value of the second threshold value Q0.

  FIG. 6 is a graph showing the correction characteristics, where the vertical axis indicates the correction value and the horizontal axis indicates the degree of deterioration. A straight line G60 is a graph showing the correction characteristics. As indicated by the straight line G60, the correction characteristic has a characteristic that increases linearly as the degree of deterioration increases. The correction value is 1 when the degree of deterioration is 0. That is, when the capacitor 4 is not deteriorated, the correction value is 1, and the second threshold value Q0 is not corrected. On the other hand, since the correction value gradually increases as the degree of deterioration increases, the value of the second threshold value Q0 of the capacitor 4 that has deteriorated is larger than that of the capacitor 4 that has not deteriorated.

  When Modification 2 is combined with Modification 1, the second threshold value Q0 specified using the straight line G50 in Modification 1 may be corrected with the correction value specified using the straight line G60 in Modification 2.

1 Engine 2 B-ISG
3 Battery 4 Capacitor 5 Step-down Circuit 6 Electric Load 7 Gear Drive Starter 14 Voltage Sensor 15 Current Sensor 17 Voltage Sensor 210 PCM
211 Integration Unit 212 IS Control Unit 213 IS Flag Storage Unit 214 IS Number Storage Unit 215 Integrated Value Storage Unit

Claims (6)

An engine automatic stop control device for controlling idle stop of an engine for driving a vehicle,
Lead battery,
A storage battery having a faster charge / discharge rate than the lead battery;
The power in at least one of the lead battery and the storage battery is used to restart the engine in an idle stop state, and is driven by the engine at least when the vehicle is decelerated to generate power. The lead battery and the storage battery Generator with motor function to charge
A current detection unit for detecting a current flowing in the lead battery;
An integration unit that calculates the charge / discharge amount integrated value by integrating the charge current value and the discharge current value of the lead battery detected by the current detection unit;
When the calculated charge / discharge amount integrated value is equal to or less than a first threshold indicating that the amount of use of the lead battery is high with respect to the number of idle stops, the idle stop is permitted regardless of the remaining capacity of the storage battery. If the accumulated charge / discharge value is greater than the first threshold, and the remaining capacity of the storage battery is greater than a predetermined second threshold, the engine is automatically stopped with an idle stop control unit that permits the idle stop. Control device.   The engine automatic stop control device according to claim 1, wherein the idle stop control unit increases the first threshold as the number of idle stops increases.   3. The engine automatic stop control device according to claim 1, wherein the idle stop control unit increases the second threshold value as the calculated charge / discharge amount integrated value increases.   In the case where the calculated charge / discharge amount integrated value is not less than the first threshold value and the remaining capacity of the storage battery is not more than the second threshold value, the idle stop control unit determines that the remaining capacity is the second threshold value. The engine automatic stop control device according to any one of claims 1 to 3, wherein the engine is idle-stopped after the storage battery is forcibly charged by the generator with a motor function until the engine becomes.   The engine automatic stop control device according to claim 4, wherein the idle stop control unit performs the forced charging by causing the generator with a motor function to generate power even when the vehicle is accelerated.   The engine according to any one of claims 1 to 5, wherein the idle stop control unit detects a degree of deterioration of the storage battery and increases the second threshold as the detected degree of deterioration increases. Automatic stop control device.