JP2005090456A - Power generation control device for idling stop vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power generation control device for an idling stop vehicle, improving drivability by actualizing smooth start of the vehicle even during prohibiting idling stop control where generating load is increased. <P>SOLUTION: During prohibiting the idling stop control (YES in Step S2), even in the case that SOC for a battery is less than a preset value Ksoc and requires an increase of target generating voltage V of an alternator for charge (YES in Step S12), when the travel of the vehicle is started (YES in Step S14), the target generating voltage V is held down to a second set value VL until a timer TMR gets to zero to reduce generating load on an engine (Steps S20, S22). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a power generation control device for an idle stop vehicle that temporarily automatically stops an engine when the vehicle is stopped.

  2. Description of the Related Art In recent years, idle stop vehicles have been put into practical use in which an engine is automatically stopped temporarily for the purpose of reducing fuel consumption and emission when the vehicle is stopped due to traffic light or traffic jams. In the idle stop control performed in this idle stop vehicle, the engine is stopped when an engine stop condition such as a brake operation, a vehicle speed of 0 km / h, and a shift position of the automatic transmission is a D (drive) position is satisfied. When the engine start condition indicating the driver's intention to start, such as stopping the brake operation, is satisfied, the engine is started by the starter to prepare for the start.

  In this type of idle stop vehicle, if the engine is stopped when the SOC (state of charge) of the battery mounted on the vehicle is low, the starter motor cannot be started due to insufficient driving force of the starter motor at the subsequent start. There is a fear. Therefore, in this situation, the idle stop control is prohibited, and even if the engine stop condition is satisfied, the engine operation is continued to prevent the start failure.

While the idle stop control is prohibited, the power generation amount of the alternator is controlled to increase in order to recover the lowered SOC early, so the power generation load acting on the engine inevitably increases and the vehicle starts in this state. If this happens, there will be a problem that dullness will occur and drivability will deteriorate.
On the other hand, there has been proposed an idle stop vehicle that reduces the power generation load during prohibition of idle stop control (see, for example, Patent Document 1). In the idle stop vehicle described in Patent Document 1, the power generation amount of the alternator is reduced during idle operation of the engine while the idle stop control is prohibited, thereby reducing the power generation load and suppressing the deterioration of fuel consumption. .
JP 2000-192830 A

  Even in the idle stop vehicle of the above-mentioned Patent Document 1, when the engine rotational speed increases with the start of the vehicle and deviates from the idle range, the decrease in the power generation amount of the alternator is interrupted and the normal power generation control is resumed. Of course, the power generation load acting on the engine has increased, and the deterioration of drivability due to the above-mentioned slack cannot be avoided. In addition, although the power generation amount is increased for the recovery of the SOC, the power generation amount during the idle operation is reduced, so that the recovery of the SOC and the resumption of the idle stop control are delayed. This caused a problem that the fuel consumption and emission reduction effect of stop control was hindered.

  An object of the present invention is to realize smooth vehicle start-up and improve drivability even during the prohibition of idle stop control in which the power generation load increases, while ensuring sufficient power generation and restarting idle stop control early. An object of the present invention is to provide a power generation control device for an idle stop vehicle.

  In order to achieve the above object, the invention according to claim 1 executes idle stop control for starting the engine when a preset engine start condition is satisfied while stopping the engine when a preset engine stop condition is satisfied. In addition, in an idle stop vehicle that prohibits idle stop control when a preset prohibition condition is satisfied, a remaining capacity estimating means that estimates a remaining capacity of a battery mounted on the vehicle, and a start detection means that detects the start of the vehicle, The engine is activated when the remaining capacity of the battery estimated by the remaining capacity estimating means is less than a preset first predetermined value and the start of the vehicle is detected by the start detecting means while the idle stop control is prohibited. Power generation amount suppression means for suppressing the power generation amount of the power generation means driven by the power generator.

Therefore, even when idling stop control is prohibited and the remaining capacity of the battery is less than the first predetermined value and it is necessary to increase the power generation amount of the power generation means for charging, the power generation amount suppression means generates power when starting the vehicle. Since the power generation amount of the means is suppressed, the power generation load acting on the engine as the power generation means is driven is reduced, and smooth start of the vehicle without wobbling is realized.
In addition, since the target power generation voltage is suppressed only when the vehicle starts, for example, after the vehicle starts, the power generation suppression by the power generation suppression means is stopped to ensure a sufficient power generation amount of the power generation means, and the remaining capacity of the battery Can be recovered quickly, and the idle stop control being prohibited can be resumed early.

According to a second aspect of the present invention, in the first aspect, the power generation amount suppression means decreases the suppression amount of the power generation means with respect to the power generation amount as time elapses from the start of the vehicle.
Therefore, since the amount of suppression by the power generation amount suppression means decreases with the passage of time from the start of vehicle start-up, the power generation amount is suppressed with a large amount of suppression at the beginning of the start and the power generation load acting on the engine is sufficiently reduced. Acceleration feeling according to the driver's accelerator depression can be obtained, but the subsequent power generation amount gradually increases as the suppression amount decreases, resulting in a stepped acceleration feeling compared to a sudden increase in power generation amount. Is prevented.

According to a third aspect of the present invention, in the first aspect, the remaining power of the battery estimated by the remaining capacity estimating means is determined by the remaining power estimating means when the power generation amount suppressing means performs the engine stop condition based on the establishment of the engine stop condition. When it becomes less than the second predetermined value set in advance, the setting of the power generation amount of the power generation means is suppressed.
Therefore, when the idle stop control is executed and the engine is stopped, the remaining capacity of the battery gradually decreases. However, when the remaining capacity becomes less than the second predetermined value, the power generation amount is set by the power generation amount suppression means. It is suppressed. If the remaining capacity of the battery is reduced, there is a risk that the drive power of the starter motor will become insufficient when the engine is subsequently started. However, the power generation load acting on the engine is suppressed because the power generation amount setting of the power generation means is suppressed. Even with a starter motor with insufficient driving force, the engine can be normally cranked and started quickly.

As described above, according to the power generation control device for the idle stop vehicle of the first aspect of the present invention, the vehicle can be smoothly started even during the prohibition of the idle stop control in which the power generation load is increased, and the drivability can be improved. Sufficient power generation can be secured and the idle stop control can be resumed early.
According to a power generation control device for an idle stop vehicle of a second aspect of the invention, in addition to the first aspect, the power generation amount of the power generation means is gradually increased after starting the vehicle, thereby accelerating the driver according to the accelerator depression. In addition, it is possible to prevent stepping of acceleration and further improve drivability.

  According to the power generation control device for an idle stop vehicle of the invention of claim 3, in addition to claim 1, the setting of the power generation amount of the power generation means is suppressed when the remaining capacity of the battery is reduced during the engine stop by the idle stop control. In addition, the power generation load acting on the engine at the subsequent start can be reduced, and the vehicle can be started quickly by the quick start.

[First Embodiment]
Hereinafter, a first embodiment of a power generation control device for an idle stop vehicle embodying the present invention will be described.
FIG. 1 is an overall configuration diagram showing a power generation control device for an idle stop vehicle according to the present embodiment, and an engine 1 mounted on the idle stop vehicle is configured as an intake pipe injection type gasoline engine. A throttle valve 3 and a fuel injection valve 4 are provided in the intake passage 2 of the engine 1, and the fuel injected from the fuel injection valve 4 after the flow rate of intake air introduced into the intake passage 2 is adjusted by the throttle valve 3. And is introduced into the combustion chamber 5. In the combustion chamber 5, the air-fuel mixture is ignited by a spark plug 6 at a predetermined timing, and the combustion gas after combustion is discharged to the outside through the exhaust passage 7, a catalyst and a silencer (not shown).

  An alternator 8 is disposed on one side of the engine 1, and a pulley 8 a of the alternator 8 is connected to a crank pulley 11 of the engine 1 by a belt 12 together with a water pump pulley 9 and an idler pulley 10. While the alternator 8 is connected to a battery 13 mounted on the vehicle, it is also connected to an electric load 14 such as a vehicle lamp or an air conditioner (hereinafter referred to as an air conditioner). It is rotationally driven together with the water pump pulley 9 via the belt 12 to generate electric power that covers charging of the battery 13 and power consumption by the electric load 14.

A starter motor 15 is provided on one side of the engine 1, and the starter motor 15 is configured to crank the engine 1 by engaging a pinion gear (not shown) with a ring gear on the engine 1 side. The engine 1 configured as described above is connected to an automatic transmission and mounted on a vehicle.
On the other hand, an ECU 21 provided with an input / output device (not shown), a storage device (ROM, RAM, BURAM, etc.), a central processing unit (CPU), a timer counter, etc. provided for storage of a control program, a control map, etc. (Engine control unit) is installed. On the input side of the ECU 21, the battery 13, a brake sensor 22 that detects a brake operation by the driver, a vehicle speed sensor 23 (start detection means) that detects the vehicle speed V, a shift position of the automatic transmission (a shift that is switched by an automatic shift). A shift position sensor 24 that detects the shift lever position selected by the driver, not the gear), a crank angle sensor 25 that outputs an SGT signal at predetermined intervals as the engine 1 rotates, and various other switches and sensors. Is connected. Further, the fuel injection valve 4, the spark plug 6, the alternator 8, the starter motor 15, and other devices are connected to the output side of the ECU 21.

The ECU 21 executes various controls for operating the engine 1 such as fuel injection control and ignition timing control based on each detection information described above, while fuel consumption and emission are stopped while the vehicle is stopped due to a signal waiting or traffic jam. In order to reduce the engine idling stop control, the engine 1 is automatically stopped temporarily.
Further, the ECU 21 estimates the SOC (remaining capacity) of the battery 13 based on the charge / discharge state of the battery 13 (remaining capacity estimating means), and determines the power generation state of the alternator 8 based on the target power generation voltage V set from the SOC. In addition to the control, when the SOC of the battery 13 is low, the idle stop control prohibiting process and the power generation suppression of the alternator 8 at the start of the vehicle are performed. Therefore, the outline of the idle stop control and the power generation control of the alternator 8 performed in connection with the idle stop control will be described below.

First, idle stop control will be described. Engine stop and engine start in the idle stop control are performed based on the establishment of preset engine stop conditions and engine start conditions.
In the present embodiment, the following three requirements are set as the engine stop condition, and it is determined that the engine stop condition is satisfied when all these requirements are satisfied.

1) The brake operation is detected by the brake sensor 22,
2) The vehicle speed V detected by the vehicle speed sensor 23 is 0 km / h,
3) The shift position detected by the shift position sensor 24 is a travel position such as D (drive), or N (neutral).
In the present embodiment, the following two requirements are set as engine start conditions. When both of these requirements are satisfied, that is, when it is considered that the driver is willing to start, the engine start condition is satisfied. It is determined that

4) When the brake sensor 22 releases the brake operation,
5) The shift position detected by the shift position sensor 24 is a travel position such as D,
Therefore, when the vehicle stops due to a signal waiting or traffic jam, it is determined that the engine stop condition is satisfied based on the above requirements 1) to 3), the engine 1 is stopped by stopping the fuel injection control, and then the driver When the start operation is performed, it is determined that the engine start condition is satisfied based on the requirements 4) and 5), and the engine 1 is started by restarting the fuel injection control and cranking the starter motor 15.

  On the other hand, the power generation control of the alternator 8 is performed based on a target power generation voltage setting routine shown in FIG. 2, and the ECU 21 executes the routine at a predetermined control interval. First, in step S2, it is determined whether or not idle stop control is currently prohibited. The idle stop control prohibition process is intended to prevent a situation in which the engine 13 is stopped due to insufficient driving force of the stator motor 15 due to engine stop when the SOC of the battery 13 is low. In this case, even if the engine stop condition is satisfied, the operation of the engine 1 is continued to prevent the engine from being unable to start.

  When the determination in step S2 is NO (No), the ECU 21 determines in step S4 whether the engine is currently stopped by the idle stop control, and in step S6, the SOC of the battery 13 is set to a predetermined value Ksoc (preliminary value). It is determined whether it is less than a predetermined value of 2. If any of the determinations in steps S4 and S6 is NO, the process proceeds to step S8 to set the first set value VH as the target power generation voltage V. If both the determinations in steps S4 and S5 are YES (affirmative), the process proceeds to step S10. After the transition and setting the second set value VL (<VH) as the target power generation voltage V (power generation amount suppressing means), the routine is once terminated.

Therefore, during the execution of the idle stop control, the alternator 8 is basically maintained at a sufficient power generation amount based on the first set value VH, while the engine is stopped and the SOC is low (SOC <Ksoc). The power generation amount of the alternator 8 is reduced based on the second set value VL.
On the other hand, when the idling stop control is prohibited, the ECU 21 proceeds from step S2 to step S12 to determine whether the SOC of the battery 13 is less than the predetermined value Ksoc (first predetermined value), and subsequent step S14. Thus, it is determined whether or not the vehicle speed flag F set based on the detection value of the vehicle speed sensor 23 is 1 (that is, during traveling) (start detection means). In step S12, the same predetermined value Ksoc as in step S6 is used, but the determination may be made based on a value different from that in step S6.

  When any of the determinations in steps S12 and S14 is NO, the process proceeds to step S16 to set a predetermined value Ktmr set in advance as the timer TMR, and in step S18, the second set value VL is set as the target generated voltage V. The routine ends later. Accordingly, in this case, the alternator 8 generates power based on the second set value VL, and the timer TMR continues to be set to the predetermined value Ktmr.

  If both the determinations in steps S12 and S14 are YES, it is determined in step S20 whether or not the timer TMR is 0. If the determination is NO, the routine is terminated as it is. When the setting process in step S16 is stopped, the timer TMR is sequentially subtracted from the predetermined value Ktmr, and when the timer TMR becomes 0, the ECU 21 proceeds from step S20 to step S22 to obtain the first target generated voltage V as the first generated voltage V. A set value VH is set (power generation amount suppressing means), and then the routine is terminated.

  Therefore, while the idling stop control is prohibited, basically, the alternator 8 generates power based on the second set value VL, while the SOC decreases (SOC <Ksoc) and the vehicle starts to travel ( In the vehicle speed flag F = 1), when the time corresponding to the predetermined value Ktmr elapses and the timer TMR becomes 0, the power generation amount of the alternator 8 is increased based on the first set value VH.

Next, the setting state of the target generated voltage V performed based on the above-described target generated voltage setting routine of the ECU 21 will be described with reference to the time chart of FIG.
During the execution of the idle stop control, even if the engine 1 is stopped due to the establishment of the engine stop condition (point a in FIG. 3), the first generated power generation voltage V is set as long as the SOC of the battery 13 is equal to or higher than the predetermined value Ksoc. A set value VH is set. Since the alternator 8 does not generate power when the engine is stopped, the SOC of the battery 13 gradually decreases. When the SOC becomes less than the predetermined value Ksoc, the second set value VL is set as the target generated voltage V (point b in FIG. 3). Since the SOC of the battery 13 is low, the driving force of the starter motor 15 becomes insufficient at the subsequent start (point c in FIG. 3), but the power generation load acting on the engine 1 is reduced together with the power generation amount of the alternator 8. Therefore, even if the driving force of the tail starter motor 15 is insufficient, the engine 1 can be normally cranked and the vehicle can be started quickly by quick start.

  While the idle stop control is prohibited, the operation of the engine 1 is continued even when the engine stop condition is satisfied, and the SOC of the battery is equal to or higher than the predetermined value Ksoc or the vehicle is stopped (vehicle speed). As long as the flag F = 0), the second set value VL is set as the target generated voltage V (point d in FIG. 3). For example, when the SOC of the battery becomes less than the predetermined value Ksoc (point e in FIG. 3), and then the vehicle speed flag F becomes 1 as the vehicle starts (point f in FIG. 3), the timer TMR starts subtraction. When the time corresponding to the predetermined value Ktmr elapses and the timer TMR becomes 0 (point g in FIG. 3), the target generated voltage V is changed from the second set value VL to the first set value VH as indicated by a broken line in the figure. And the power generation amount of the alternator 8 is increased.

  Therefore, even when the SOC of the battery 13 is low (SOC <Ksoc) and the target power generation voltage V of the alternator 8 needs to be increased for charging, the target power generation over a time corresponding to the predetermined value Ktmr at the start of the vehicle. Since the voltage V is suppressed to the second set value VL, the power generation load acting on the engine 1 can be reduced and a smooth vehicle start can be realized, thereby improving drivability.

  Moreover, the target power generation voltage V is suppressed only to the predetermined value Ktmr from the start of the vehicle, and after the predetermined value Ktmr has elapsed, a sufficient power generation amount of the alternator 8 is secured based on the first set value VH. It is possible to quickly recover the SOC of the battery 13 and resume the prohibited idle stop control at an early stage, and as a result, the effect of reducing fuel consumption and emission by the idle stop control can be maximized.

[Second Embodiment]
Next, a second embodiment in which the present invention is embodied in another power generation control device for an idle stop vehicle will be described. The power generation control device of the present embodiment differs from the processing of the ECU 21 regarding the target power generation voltage setting routine in comparison with that of the first embodiment, and the overall configuration is the same as that of the first embodiment shown in FIG. It is. Therefore, parts having the same configuration are denoted by common member numbers, description thereof is omitted, and processing contents of the ECU 21 which are different points are described mainly.

  The ECU 21 executes a target power generation voltage setting routine shown in FIG. 4 at a predetermined control interval. In this routine, steps S102 to S110 are executed in place of steps S20 and S22 in the routine of the first embodiment shown in FIG. 2, and only different processing is shown in FIG. That is, as described in the first embodiment, while the idle stop control is prohibited (step S2 is YES), the SOC of the battery 13 becomes less than the predetermined value Ksoc (step S12 is YES) and the vehicle starts to travel ( When step S14 is YES), the ECU 21 proceeds to step S102.

  In step S102, it is determined whether or not the timer TMR is 0. When the determination is NO, it is determined in step S104 whether or not the preset increase cycle Kt (<Ktmr) of the target generated voltage V has elapsed. If not, the routine is temporarily terminated. If the determination in step S104 is YES due to the elapse of the increase cycle Kt, after adding a predetermined value ΔV (<VH−VL) to the current target generated voltage V (second set value VL in the first case) in step S106. The process proceeds to step S108. In step S108, it is determined whether the target generated voltage V after the addition exceeds the first set value VH. If the determination is NO, the routine is terminated.

Then, until the determination in step S102 becomes YES, the target generated voltage V is added by a predetermined value ΔV in step S106 every increase period Kt, and when the added target generated voltage V exceeds the first set value VH, After moving from step S108 to step S110 and setting the first set value VH as the target generated voltage V, the routine is terminated.
As a result of the above target power generation voltage setting routine, when the idle stop control is prohibited, the SOC of the battery 13 becomes less than the predetermined value Ksoc (point e in FIG. 3), the vehicle speed flag F becomes 1 and the timer TMR is subtracted. When started (point f in FIG. 3), the target generated voltage V is increased by a predetermined value ΔV every increase period Kt starting from the second set value VL and then limited to the first set value VH. After a time corresponding to Ktmr elapses, the timer TMR becomes 0 (point g in FIG. 3).

  That is, in the first embodiment, the target power generation voltage V is increased to the first set value VH stepwise after the target generated voltage V is suppressed to the second set value VL for a time corresponding to the predetermined value Ktmr when the vehicle starts. In the present embodiment, the target power generation voltage V is gradually increased from the second set value VL by a predetermined value ΔV every increase period Kt (in other words, the suppression amount for the target power generation voltage V is increased from the vehicle start time). Decreasing with progress).

  Therefore, since the power generation load is sufficiently reduced by suppressing the target power generation voltage V in the vicinity of the second set value VL at the start of the vehicle, an acceleration feeling corresponding to the driver's accelerator depression can be obtained. Since the target power generation voltage V gradually increases to the first set value VH, it is possible to prevent the step of acceleration when the target power generation voltage V increases greatly and stepwise, thereby further improving drivability. it can.

  This is the end of the description of the embodiment, but the aspect of the present invention is not limited to this embodiment. For example, in each of the above embodiments, the engine 1 mounted on the idle stop vehicle is configured as an intake pipe injection type gasoline engine, and the engine 1 is provided with the normal alternator 8. However, the type of the engine 1, the type of the alternator 8, etc. However, the engine 1 may be configured as a diesel engine, or a starter generator having a power generation function and a starter function may be provided in the engine 1 instead of the alternator 8 and the starter motor 15.

  In each of the above embodiments, the brake operation, the vehicle speed of 0 km / h, and the shift position are set to the travel position such as D or the N position as the engine stop condition, and the brake operation is stopped and the shift is set as the engine start condition. Although the position is set to be a traveling position such as D, the stop condition and the start condition are not limited to this. For example, as an engine stop condition, the accelerator operation amount is 0 (during idle operation). May be added.

It is a whole block diagram which shows the electric power generation control apparatus of the idle stop vehicle of 1st and 2nd embodiment. It is a flowchart which shows the target electric power generation voltage setting routine which ECU of 1st Embodiment performs. It is a time chart which shows the setting condition of target electric power generation voltage. It is a flowchart which shows the target electric power generation voltage setting routine which ECU of 2nd Embodiment performs.

Explanation of symbols

1 Engine 8 Alternator (power generation means)
13 battery 21 ECU (remaining capacity estimation means, power generation amount suppression means, start detection means)
23 Vehicle speed sensor (start detection means)

Claims (3)

While the engine is stopped when a preset engine stop condition is satisfied, idle stop control is executed to start the engine when a preset engine start condition is satisfied, and when the preset prohibition condition is satisfied, In an idle stop vehicle that prohibits stop control,
A remaining capacity estimating means for estimating a remaining capacity of a battery mounted on the vehicle;
Start detection means for detecting the start of the vehicle;
When the remaining capacity of the battery estimated by the remaining capacity estimating means is less than a preset first predetermined value and the start of the vehicle is detected by the start detecting means while the idle stop control is prohibited. A power generation control device for an idle stop vehicle, comprising: a power generation amount suppression unit that suppresses a power generation amount of the power generation unit driven by the engine.   2. The power generation control device for an idle stop vehicle according to claim 1, wherein the power generation amount suppression unit decreases the suppression amount of the power generation unit with respect to the power generation amount as time elapses from the start of the vehicle.   The power generation amount suppressing means is a second predetermined preset value in which the remaining capacity of the battery estimated by the remaining capacity estimating means is set in advance while the engine is stopped based on the establishment of the engine stop condition by executing the idle stop control. 2. The power generation control device for an idle stop vehicle according to claim 1, wherein setting of the power generation amount of the power generation means is suppressed when it becomes less than a value.

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