JP2006081331A - Controller for vehicular alternator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller for a vehicular alternator capable of preventing an occupant from having an uncomfortable feeling caused by variations in the intensity of a headlamp at voltage switching, in the vehicular alternator which is constituted so as to gradually decrease voltage in conducting switching control of generated voltage between a first voltage for promoting charging into a battery and a second voltage for inhibiting charging into the battery. <P>SOLUTION: In switching the first voltage V1 to the second voltage V2, a generated voltage Va is reduced at a reducing speed k corresponding to a battery charging state so that the reducing speed of the battery voltage Vb may be roughly constant regardless of a charging state (remaining battery capacity C) of the battery 3. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a control device for a vehicle generator that supplies electric power to a vehicle electrical load and charges a battery, and belongs to the technical field of power generation voltage control of a vehicle generator.

  A vehicle such as an automobile is provided with a battery for supplying electric power to an electric load such as an air conditioner or a headlamp, and a generator for supplying electric power to the electric load and charging the battery. For example, as disclosed in Patent Document 1, for the purpose of regeneration of braking energy and improvement in fuel efficiency of the engine, when the vehicle is in a deceleration state, the vehicle is controlled to a first voltage that promotes charging of the battery. In the non-decelerating state, the second voltage may be controlled to suppress charging of the battery.

  By the way, if the power generation voltage is controlled to be switched between the first voltage and the second voltage as described above, the brightness of the headlamp may change when the voltage is switched, and the passenger may feel uncomfortable. For example, as disclosed in Patent Document 2, when the generated voltage is switched, there is one in which the voltage is gradually changed by a predetermined voltage every predetermined time, that is, at a predetermined voltage change rate.

JP-A-5-137275 JP-A-5-103433

  By the way, when the power generation voltage of the generator is switched from the first voltage to the second voltage, the battery terminal voltage decreases following the decrease in the power generation voltage. The rate of decrease of the battery terminal voltage in this transient state Is dependent on the remaining battery capacity at the time of switching (battery charge state) due to the discharge characteristics of the battery. For example, as shown in FIG. 7, when the remaining capacity of the battery is large, it becomes smaller (slowly decreases), When the remaining capacity is small, it becomes large (decreases rapidly). In other words, just by controlling the generated voltage as in the above-mentioned Patent Document 2, the rate at which the battery terminal voltage decreases does not become constant, resulting in variations in the speed of change in the brightness of the headlamps, which makes the passenger feel uncomfortable enough Cannot be resolved.

  Therefore, the present invention switches the generated voltage to a first voltage that promotes charging of the battery and a second voltage that suppresses charging of the battery, and switches from the first voltage to the second voltage. Provided is a control device for a vehicular generator that can prevent a passenger from feeling uncomfortable due to a change in the brightness of a headlamp at the time of voltage switching in a vehicular generator configured to gradually decrease the voltage at the time The task is to do.

  In order to solve the above problems, the present invention is configured as follows.

  First, an invention according to claim 1 of the present application (hereinafter referred to as a first invention) includes a battery that supplies electric power to a vehicle electric load including a headlamp, and an electric power that is driven by an engine to supply the electric load and the battery. The generator to be supplied, driving state detection means for detecting the driving state of the vehicle, and charging of the generator with the generated voltage of the generator in accordance with the driving state of the vehicle detected by the driving state detection means And a power generation voltage control means for gradually reducing the power generation voltage when switching from the first voltage to the second voltage. The vehicle generator control device is provided with a charge state detection means for detecting the charge state of the battery, and the generated voltage control means is configured to switch from the first voltage to the second voltage. As the rate of decrease in serial regardless battery charge state detected by the charge state detecting means battery terminal voltage is substantially constant, the power generation voltage and decreases at a decrease rate corresponding to the battery state of charge.

  Further, the invention according to claim 2 of the present application (hereinafter referred to as the second invention) according to the first invention is the engine speed detecting means for detecting the engine speed as the driving state detecting means, and whether the vehicle is in a decelerating state. And an engine speed detected by the engine speed detecting means in a state where the deceleration state detecting means detects whether the vehicle is in a decelerating state. When the engine speed is equal to or higher than the first predetermined rotational speed, the fuel supply to the engine is cut, and after the fuel supply cut, the engine rotational speed decreases to a second predetermined rotational speed lower than the first predetermined rotational speed. Is provided with fuel supply control means for resuming fuel supply to the engine, and when the deceleration state detecting means detects deceleration of the vehicle, the power generation voltage control means sets the power generation voltage of the generator to the first. And after the generated voltage is controlled to the first voltage by the generated voltage control means, the generated voltage control means causes the generated voltage to decrease at a rate corresponding to the state of charge of the battery. A reduction start rotational speed setting means for setting the power generation voltage decrease start rotational speed so that the power generation voltage decreases to the second voltage in the vicinity of the second predetermined rotational speed when the voltage is decreased from one voltage to the second voltage; Further, the decrease start rotation speed setting means sets the decrease start rotation speed at a predetermined time before the engine rotation speed decreases to the decrease start rotation speed set by the setting means. When the engine speed is reduced to the reduction start speed, the power generation voltage starts decreasing at the speed of decrease.

  The invention according to claim 3 of the present application (hereinafter referred to as the third invention) is provided with deceleration detecting means for detecting deceleration of the engine speed in the deceleration state in the second invention, and starts to decrease. When setting the power generation voltage decrease start rotation speed, the rotation speed setting means sets the decrease start rotation speed lower when the deceleration detected by the deceleration detection means is small than when it is large. Features.

  In the invention according to claim 4 of the present application (hereinafter referred to as the fourth invention), in any one of the first invention to the third invention, the charging state detection means detects the remaining capacity of the battery as the charging state of the battery. The generated voltage control means, when switching from the first voltage to the second voltage, reduces the decrease rate of the generated voltage when the remaining capacity of the battery detected by the charge state detecting means is small compared to when it is large. It is characterized by that.

  Next, the effect of the present invention will be described.

  First, according to the first invention, the generated voltage is controlled to be switched between the first voltage that promotes charging of the battery and the second voltage that suppresses charging of the battery. When switching to, the generated voltage is reduced at a rate that corresponds to the battery charge state so that the rate at which the battery terminal voltage decreases is substantially constant regardless of the battery charge state. The change in length is substantially constant regardless of the state of charge of the battery, so that a sense of incongruity of the occupant is eliminated, and regeneration of braking energy and improvement in fuel consumption of the engine by the power generation voltage switching control can be achieved.

  When the vehicle is in a deceleration state, engine fuel cut control may be performed for the purpose of improving the fuel consumption of the engine. That is, when the vehicle is in a deceleration state and the engine speed is equal to or higher than the first predetermined speed, the fuel supply to the engine is cut, and after the fuel supply is cut, the engine speed is set to the first predetermined speed. When the engine speed is reduced to a second predetermined rotational speed lower than the engine speed, the fuel supply to the engine is resumed, and fuel is consumed if the above-described power generation voltage is controlled to the first voltage during the fuel cut. It is possible to charge the battery without any charge, so that it is possible to reduce the load on the engine when the fuel is not being cut, in other words, when the fuel is not being cut. Can be made.

  Here, when the fuel cut is executed as described above, the engine speed is lower than that at the start of the fuel cut when the fuel supply is restarted. is there. Therefore, it is conceivable to reduce the power generation voltage of the generator to the second voltage at the rate of decrease before the engine speed decreases to the second predetermined speed. If not set, for example, the charging period of the battery by the first voltage during fuel cut is shortened, and the effect of improving fuel efficiency is impaired.

  However, according to the second invention, when the generated voltage is decreased from the first voltage to the second voltage at a decrease rate according to the remaining capacity of the battery, the generated voltage reaches the second voltage in the vicinity of the second predetermined rotational speed. Since the generation voltage reduction start rotational speed is set so as to decrease, it is possible to prevent the occurrence of engine stall while preventing the passenger from feeling uncomfortable due to the change in brightness of the headlamp, and the engine rotational speed is set to the second predetermined speed. The battery can be charged with the first voltage until the rotation speed decreases to the vicinity of the rotation speed, and the regeneration of the braking energy and the improvement of the fuel consumption can be further effectively achieved.

  It is most preferable that the generated voltage is reduced to the second voltage just when the engine speed is reduced to the second predetermined speed, but a little before or slightly before the time when the engine speed is reduced to the second predetermined speed. Even if the power generation voltage is lowered to the second voltage later, the effects of the present invention can be achieved.

  Further, according to the third invention, in the second invention, when setting the power generation voltage decrease start rotational speed, when the deceleration is small, the power generation voltage decrease start rotational speed is made lower than when the deceleration is large. When the voltage is switched from the first voltage to the second voltage, the generated voltage can be accurately reduced to the second voltage in the vicinity of the second predetermined rotational speed regardless of the magnitude of the deceleration. It is possible to effectively regenerate braking energy and improve fuel efficiency.

  Further, the fourth aspect of the present invention embodies a battery state-of-charge detection means. According to the fourth aspect of the present invention, when the remaining capacity of the battery is small, the rate of decrease in the generated voltage is made smaller than when the remaining capacity is large. That is, since the generated voltage is gradually reduced, the battery terminal voltage decrease rate is moderate even when the remaining battery capacity is small. As a result, the battery terminal voltage decrease rate is substantially constant regardless of the remaining battery capacity. It will be.

  Hereinafter, embodiments of the present invention will be described.

  As shown in FIG. 1, a vehicle 1 according to the present embodiment includes a battery 3 that supplies power to a vehicle electrical load 2 such as an air conditioner, a headlamp, and a defogger, and the vehicle electrical load driven by an engine. 2 and a generator 4 for supplying power to the battery 3. The battery 3 is a lead storage battery generally used for automobiles, and the generator 4 includes an alternator and a regulator for adjusting the generated voltage.

  The vehicle 1 is provided with a control unit 10 that controls the generated voltage Va of the generator 4. The control unit 10 includes a signal from a current sensor 11 that detects the charge / discharge current I of the battery 3. A signal from the vehicle speed sensor 12 that detects the vehicle speed S, a signal from the accelerator opening sensor 13 that detects the accelerator opening A, and a signal from the engine rotation sensor 14 that detects the engine speed Ne are input. .

  The control unit 10 detects the initial charge state of the battery 3, that is, the initial capacity of the battery 3 (remaining capacity at the time of engine start) from the charge / discharge current I detected by the current sensor 11 when the engine is started. The current remaining capacity C of the battery 3 is calculated by adding the charge / discharge current I detected by the current sensor 11 to the capacity, that is, the state of charge of the battery 3 is detected.

  The control unit 10 determines the power generation voltage Va of the generator 4 based on the signals from the various sensors and the battery remaining capacity C when the remaining capacity C is equal to or higher than the first capacity (for example, 60% of the battery rated capacity). According to the flowchart of FIG. 2 to be described later, the first voltage V1 (for example, 14.5V) that promotes the charging of the battery 3 and the charging of the battery 3 that is lower than the first voltage V1 are suppressed to a discharged state. When switching to the second voltage V2 (for example, 12V) and the remaining battery capacity C is smaller than the first capacity, the second capacity is larger than the first capacity (for example, 80% of the rated battery capacity) until the second capacity is reached. After controlling to 1 voltage V1, it returns to the voltage switching control by the flowchart of FIG.

  The vehicle 1 is in a decelerating state when the engine rotational speed Ne detected by the engine rotational sensor 14 is equal to or higher than a first predetermined rotational speed ε (hereinafter referred to as “fuel cuttable rotational speed ε”). The fuel supply to the engine is resumed when the fuel supply to the engine is cut and the engine speed Ne drops to a second predetermined speed β (hereinafter referred to as “fuel return speed β”; β <ε). It is comprised so that.

  Hereinafter, the generated voltage control by the control unit 10 will be described in detail with reference to the flowchart of FIG.

  First, in step S1, various signals of the vehicle speed S, the accelerator opening A, and the engine speed Ne detected by the various sensors are input, and the current remaining capacity C of the battery 3 is input. In step S2, Based on the vehicle speed S and the accelerator opening A, it is determined whether or not the vehicle is decelerating. Here, it is determined that the vehicle is decelerating when the vehicle speed S is not 0 (zero) and the accelerator opening A is 0 (zero). If it is not decelerating in step S2 (NO), in step S3, the generated voltage Va of the generator 4 is controlled to the second voltage V2, and if it is decelerating (YES), in step S4, the current engine It is determined whether or not the fuel is being cut. If the fuel cut is not in progress (NO), the power generation voltage Va of the generator 4 is controlled to the second voltage V2 in the above-described step S3. If the fuel cut is in progress (YES), in step S5, the current It is determined whether or not the engine speed Ne has decreased to a power generation voltage decrease start rotational speed γ, which will be described later. If the rotation speed has not decreased below the decrease start rotational speed γ (NO), the generated voltage Va is controlled to the first voltage V1 in step S6. Next, in step S7, it is determined whether or not the current engine speed Ne has decreased below the determined engine speed α. Here, the determination rotational speed α is smaller than the fuel-cuttable rotational speed ε and larger than the decrease start rotational speed γ and the fuel return rotational speed β, and is set in advance. If the engine speed does not fall below the determined rotational speed α (NO), the process returns. If the rotational speed falls below the determined rotational speed α (YES), the generated voltage Va is determined based on the current remaining battery capacity C in step S8. Is set to a power generation voltage decrease rotational speed γ (hereinafter referred to as “decrease start rotational speed γ”) that starts a decrease toward the second voltage V2, and a return speed k of the power generation voltage Va is set, and the process returns.

  Here, as shown in the map of FIG. 3, the decrease rate k is set to a larger value as the remaining battery capacity C is smaller, that is, when the battery charge state is not good. This is because if the rate of decrease of the battery terminal voltage Vb when switching the generated voltage Va is made constant regardless of the remaining battery capacity C, the generated voltage decreases as the remaining battery capacity C decreases for the reason described in the background art. This is because Va needs to be lowered gradually.

  Further, as shown in the map of FIG. 4, the decrease start rotation speed γ is a value smaller than the determination rotation speed α and larger than the fuel return rotation speed β, and the first generation voltage Va is reduced at the decrease speed k. When the voltage V1 is decreased to the second voltage V2, the remaining battery capacity C is set such that the generated voltage Va is decreased to the second voltage V2 when the engine speed Ne is decreased to the fuel return speed β. The smaller the value is, that is, the better the battery is charged, the smaller the value is set to a value closer to the fuel return speed β. Note that the map of the reduction start rotational speed γ in FIG. 4 is for the case where the deceleration of the engine rotational speed Ne is an average deceleration in a normal operating state, and as will be described later, the map rotates according to the deceleration. The number γ may be corrected.

  On the other hand, if it is determined in step S5 that the current engine speed Ne has decreased below the predetermined engine speed γ (YES), in step S9, the generated voltage Va is directed toward the second voltage V2 at a decreasing speed k. Reduce.

  Next, the effect | action by this Embodiment is demonstrated.

  It is assumed that the vehicle 1 is decelerating and the fuel cut is being performed, and the power generation voltage Va of the generator 4 is controlled to the first voltage V1. In this case, according to the present embodiment, when the engine speed Ne decreases to the determination speed α, the power generation voltage Va decreases at the rate k and the decrease start speed γ based on the remaining battery capacity C at this time. Is set. When the engine speed Ne decreases to the decrease start speed γ, the generated voltage Va begins to decrease at the decrease speed k toward the second voltage V2, and the engine speed Ne reaches the fuel return speed β. Almost simultaneously with the decrease, the voltage decreases to the second voltage V2.

  In this case, according to the present embodiment, the rate of decrease k decreases as the remaining battery capacity C decreases as shown in FIG. 3, and the decrease start rotational speed γ decreases as shown in FIG. The lower the C, the higher. For example, when the remaining battery capacity C is large (for example, when the remaining capacity C is c1), as shown in FIGS. 3 and 4, the decrease speed k is a relatively large value k1, and the decrease start rotational speed γ is the fuel return. It becomes a low value γ1 in the vicinity of the rotational speed β. According to this, as indicated by the symbol A in FIG. 5, the generated voltage Va decreases relatively rapidly from the point where the engine speed Ne is close to the fuel return speed β, and the fuel return speed at the engine speed Ne. The voltage drops to the second voltage V2 almost simultaneously with the drop to β. At that time, since the battery terminal voltage Vb decreases after the decrease in the generated voltage Va due to the large remaining capacity C, even if the generated voltage Va is decreased relatively abruptly as described above, As shown in (b), it will gradually decrease.

  On the other hand, when the remaining battery capacity C is small (for example, when the remaining capacity C is c2), the decrease speed k is a relatively small value k2, and the decrease start rotational speed γ is considerably higher than the fuel return rotational speed β. The value is γ2. According to this, as indicated by the symbol C in FIG. 5, the generated voltage Va gradually decreases from a point in time before the engine speed Ne decreases to the fuel return speed β, and the fuel return at the engine speed Ne occurs. The second voltage V2 is reached almost simultaneously with the decrease to the rotational speed β. At this time, the battery terminal voltage Vb reacts sensitively to the decrease in the generated voltage Va due to the small remaining capacity C. However, since the decrease in the generated voltage Va itself is performed slowly, As shown in FIG. 4, the battery capacity gradually decreases with a slope approximately the same as that when the remaining battery capacity C is large.

  As described above, according to the present embodiment, the power generation voltage Va is controlled to be switched between the first voltage V1 that promotes charging of the battery 3 and the second voltage V2 that suppresses charging of the battery 3. , When switching from the first voltage V1 to the second voltage V2, the battery charge state (battery remaining capacity) is set so that the rate of decrease of the battery terminal voltage Vb becomes substantially constant regardless of the battery charge state (battery remaining capacity C). C), the generated voltage Va is decreased at a decrease rate k according to C), so that the change in the brightness of the headlamp at the time of switching the generated voltage is substantially constant regardless of the state of charge of the battery 3, and the passenger's uncomfortable feeling is eliminated. At the same time, regeneration of braking energy and improved fuel consumption of the engine can be achieved by power generation voltage switching control.

  Further, when the generated voltage Va is reduced from the first voltage V1 to the second voltage V2 at the rate of decrease k corresponding to the remaining capacity C of the battery 3, the generated voltage Va is in the vicinity of the fuel return rotational speed β in the vicinity of the second voltage V2. Since the generation voltage decrease start rotational speed γ is set so as to decrease to the maximum, the occurrence of engine stall can be prevented while preventing the passenger from feeling uncomfortable due to the change in brightness of the headlamp, and the engine rotational speed Ne is The battery 3 can be charged with the first voltage V1 until the fuel revolution speed Ne is substantially reduced, and braking energy regeneration and fuel efficiency can be further effectively achieved.

  It is most preferable that the power generation voltage Va is reduced to the second voltage V2 just when the engine speed Ne is reduced to the fuel return speed β, but at the time when the engine speed Ne is reduced to the fuel return speed β. Even if the power generation voltage Va drops to the second voltage V2 slightly before or after a while, the above-described effects can be achieved.

  Specifically, when the remaining capacity C of the battery 3 is small, the rate of decrease k of the generated voltage Va is reduced, that is, the generated voltage Va is gradually decreased, compared to when the remaining capacity C is large. Even when C is small, the rate of decrease of the battery terminal voltage Vb becomes gradual. As a result, the rate of decrease of the battery terminal voltage Vb becomes substantially constant regardless of the remaining capacity C of the battery 3.

  In the above embodiment, when setting the decrease start rotation speed γ and the decrease speed k of the generated voltage Va, based on the battery charge state (battery remaining capacity C) at the time when the power generation voltage Va decreases below the determination rotation speed α. However, the present invention is not limited to this. For example, the battery detected at any timing from when the fuel cut is started until the engine speed Ne decreases to the above-described determination speed α. 3 may be set based on the state of charge 3. In addition, it is based on the latest charge state that it is based on the battery charge state (battery remaining capacity C) at the time of decreasing to the said determination rotation speed (alpha), and is the best.

  Further, in the above embodiment, when detecting the initial charge state of the battery 3, the detection is made from the charge / discharge current detected by the current sensor 11 when the engine is started. The determination may be made from the voltage Vb.

  By the way, the time required for the engine speed Ne to decrease from the decrease start speed γ to the fuel return speed β depends on the operating state of the vehicle, for example, the deceleration of the engine speed Ne. Therefore, as shown in FIG. 6, when the map of the above-mentioned reduction start rotational speed γ (FIG. 4) is set with reference to a case where the deceleration is medium, for example, when the deceleration is large, the power generation voltage Va is The engine speed Ne decreases to the fuel return speed β earlier than the second voltage V2 as shown by, while the generated voltage Va is a sign when the deceleration is small. As shown by the symbol F, the engine speed Ne decreases to the second voltage V2, while the engine speed Ne decreases to the fuel return speed β later than that. That is, a difference occurs between the time when the engine speed Ne decreases to the fuel return speed β and the time when the generated voltage Va decreases to the second voltage V1, and the above-described braking energy regeneration and engine fuel efficiency improvement are reduced. End up.

  Therefore, for example, when the deceleration is small, the reduction start rotational speed γ is corrected to a lower value γs than when the deceleration is medium, and when the deceleration is large, the decrease is smaller than when the deceleration is medium. The starting rotational speed γ is corrected to a large value γl. According to this, when the deceleration is small, the generated voltage Va begins to decrease as indicated by the sign key when the engine speed Ne decreases to the rotational speed γs, and when the deceleration is large, the engine speed Ne. When the engine speed decreases to the rotational speed γl, the power generation voltage Va begins to decrease as indicated by the reference sign K. In either case, the time when the engine speed Ne decreases to the fuel return speed β and the power generation voltage Va The time when the voltage drops to the second voltage V1 coincides with high accuracy, so that regeneration of braking energy and improvement of fuel efficiency of the engine can be effectively achieved.

  That is, when the reduction start rotational speed γ is set, when the deceleration is small, if the reduction start rotational speed γ is made lower than when it is large, power generation is performed when switching from the first voltage V1 to the second voltage V2. The voltage Va can be accurately reduced to the second voltage V2 in the vicinity of the fuel return rotational speed β, and as a result, regeneration of braking energy and improvement in fuel efficiency can be achieved more effectively. is there.

  The present invention can be widely applied to control devices for vehicle generators.

It is a lineblock diagram of facilities for vehicles and a control device concerning an embodiment of the invention. It is an example of the flowchart of electric power generation voltage control. It is a characteristic map of the generation voltage fall speed with respect to a battery remaining capacity. It is a characteristic map of the generation voltage fall start rotation speed with respect to a battery remaining capacity. It is an example of the time chart for demonstrating the effect | action by this Embodiment. It is explanatory drawing about the setting of the generation voltage fall start rotation speed which considered the deceleration of the vehicle. It is explanatory drawing of the battery terminal voltage fall characteristic at the time of power generation voltage switching.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle 2 Electric load for vehicles 3 Battery 4 Generator 10 Control unit (Operation state detection means, power generation voltage control means, charge state detection means, deceleration state detection means, reduction start rotation speed setting means, deceleration detection means)
11 Current sensor 12 Vehicle speed sensor (Driving state detection means)
13 Accelerator opening sensor (operating state detection means)
14 Engine rotation sensor (operating state detection means, engine speed detection means)
α Judgment speed β Fuel return speed (second predetermined speed)
γ Generation voltage drop start rotation speed ε Fuel-cuttable rotation speed (first predetermined rotation speed)

Claims (4)

A battery for supplying electric power to a vehicle electric load including a headlamp; a generator driven by an engine for supplying electric power to the electric load and the battery; operating state detection means for detecting an operating state of the vehicle; In accordance with the driving state of the vehicle detected by the state detection means, the power generation voltage of the generator is switched between a first voltage that promotes charging of the battery and a second voltage that suppresses charging of the battery. And a generator control device for a vehicle provided with a generation voltage control means for gradually decreasing the generation voltage when switching from the first voltage to the second voltage, and detecting the state of charge of the battery. Charge state detection means is provided, and the generated voltage control means switches the battery voltage regardless of the battery charge state detected by the charge state detection means when switching from the first voltage to the second voltage. As the rate of decrease in luster terminal voltage becomes substantially constant, the control unit of the vehicle generator, characterized in the power generation voltage lowering at a reduced speed in accordance with the battery state of charge. As the driving state detecting means, an engine speed detecting means for detecting the engine speed and a deceleration state detecting means for detecting whether or not the vehicle is in a decelerating state are provided, and the vehicle is decelerated by the decelerating state detecting means. When the engine speed detected by the engine speed detecting means is equal to or higher than the first predetermined speed in the state where it is detected that the engine is in a state, the fuel supply to the engine is cut and the fuel supply cut Thereafter, fuel supply control means is provided for restarting fuel supply to the engine when the engine speed has decreased to a second predetermined speed lower than the first predetermined speed. When deceleration of the vehicle is detected by the state detection means, the power generation voltage of the generator is controlled to the first voltage, and the power generation voltage is controlled by the power generation voltage control means. When the generated voltage control means decreases the generated voltage from the first voltage to the second voltage at a decrease rate according to the state of charge of the battery, the generated voltage is near the second predetermined rotation speed. A reduction start rotation speed setting means for setting the power generation voltage decrease start rotation speed so as to decrease to two voltages, and the decrease start rotation speed setting means is configured to start the decrease in which the engine rotation speed is set by the setting means; The decrease start rotation speed is set at a predetermined time before the rotation speed decreases, and the generated voltage control means reduces the generated voltage at the decrease speed when the engine rotation speed decreases to the decrease start rotation speed. 2. The control device for a vehicle generator according to claim 1, wherein the control device is started. A deceleration detecting means for detecting a deceleration of the engine speed in the deceleration state is provided, and the reduction start rotational speed setting means is detected by the deceleration detection means when setting the generated voltage reduction start rotational speed. 3. The control device for a vehicular generator according to claim 2, wherein when the deceleration is small, the lowering rotation speed is set lower than when the deceleration is large. The state of charge detection means detects the remaining capacity of the battery as the state of charge of the battery, and the power generation voltage control means detects the remaining capacity of the battery detected by the state of charge detection means when switching from the first voltage to the second voltage. 4. The control device for a vehicular generator according to any one of claims 1 to 3, wherein when the amount is small, the rate of decrease in the generated voltage is made smaller than when the amount is large.

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