JP3599955B2

JP3599955B2 - Vehicle charge control device

Info

Publication number: JP3599955B2
Application number: JP15023197A
Authority: JP
Inventors: 昭治堺; 博英佐藤
Original assignee: Denso Corp; Nippon Soken Inc
Current assignee: Denso Corp; Soken Inc
Priority date: 1997-05-22
Filing date: 1997-05-22
Publication date: 2004-12-08
Anticipated expiration: 2017-05-22
Also published as: JPH10327542A

Description

【０００１】
【発明の属する技術分野】
本発明は車両に搭載されたバッテリの充電を制御する車両用充電制御装置に関する。
【０００２】
【従来の技術】
車両用充電制御装置は、バッテリ電圧が調整電圧となるようにオルタネータのフィールド電流がレギュレータにより制御されるようになっている。現在の車両用充電制御装置では、調整電圧はバッテリの充電を効率よく行うためにバッテリの定格電圧（例えば１２Ｖ）よりも高く（１３．５〜１４．５Ｖ程度）設定されている。しかしながら高速走行状態で電気負荷が低負荷状態のときには過充電気味となってエンジンの負担を増大し燃費を悪化させる上、バッテリの液減りを助長する。そこで特開昭６２−３７０２５号公報記載の自動車用蓄電池充電システムでは、バッテリ電圧を検出し、これが所定の値よりも低下すると過放電状態と判断して調整電圧を高く設定して充電受け入れ性を高め、検出されたバッテリ電圧が所定の値よりも高いときには過充電状態と判断して調整電圧を低く設定して充電受け入れ性を抑制するようにしている。
【０００３】
【発明が解決しようとする課題】
ところで特開昭６２−３７０２５号公報記載の自動車用蓄電池充電システムでは、バッテリが満充電に近くバッテリ電圧が高ければ調整電圧が低く設定される。しかしバッテリ電圧はバッテリ放電状態となるアイドリング時であっても充電分極の影響で通常よりも高めに検出されるから高負荷で低速走行が続くとバッテリが過放電に到るまで調整電圧が高く設定されずに充電不足を生じ、エンジン再始動時に必要なバッテリ残量を確保できないおそれがある。
【０００４】
また交通が比較的良好に流れてバッテリ電圧が平均的に高くとも、電気負荷が過大であればバッテリの充電を十分に行い得ず、かかる場合に調整電圧を低く設定するのでは充電不足となってしまうおそれがある。
【０００５】
そこで本発明では、簡単な構成で車両の走行状態や電気負荷の状態に応じて適切な充電制御を行い過充電による燃費の悪化やバッテリの液減りを防止するとともに、バッテリの充電不足をも防止することのできる車両用充電制御装置を提供することを目的とする。
【０００６】
【課題を解決するための手段】
発明者等は電気負荷が低いほど、車速が高いほどすなわちバッテリの充電が十分に行い得る状態にあるほどバッテリ電圧のばらつきが小さく、一方、電気負荷が高いほど、車速が低いほどすなわちバッテリの充電が十分に行い得ない状態にあるほどバッテリ電圧のばらつきが大きいという知見を得た。本発明はかかる知見に基づいてなされたもので、請求項１記載の発明では、バッテリ電圧が予め設定した調整電圧となるようにオルタネータを制御するレギュレータを備えた車両用充電制御装置に、所定時間におけるバッテリ電圧のばらつきを演算するばらつき演算手段と、ばらつき演算手段により演算されたバッテリ電圧のばらつきが小さいほど調整電圧を低く設定する調整電圧設定手段とを設ける。
【０００７】
バッテリ電圧のばらつきが小さいほどバッテリの充電が十分に行い得る状態と判断できるから、調整電圧を低く設定することによりバッテリの過充電や液減りが防止されエンジン負荷が軽減され燃費が向上する。逆にバッテリ電圧のばらつきが大きいほどバッテリの充電が十分に行い得ない状態と判断できるから、調整電圧を高く設定することにより充電不足が防止される。
【０００８】
請求項２記載の発明では、バッテリ電圧のばらつきとともに平均値演算手段により上記所定時間におけるバッテリ電圧の平均値を演算し、これらの結果に基づいてアイドル回転数設定手段がアイドル回転数を増減する構成とする。
【０００９】
アイドル回転数設定手段は、バッテリ電圧のばらつきとバッテリ電圧の平均値とをそれぞれその所定のしきい値と比較し、バッテリ電圧のばらつきがそのしきい値以上であればバッテリの充電が十分に行い得ない状態と判断し、アイドル回転数の目標値を上げることにより充電不足が防止される。またバッテリ電圧のばらつきがそのしきい値以下でありかつバッテリ電圧の平均値がそのしきい値よりも低いとき充電量の少ないアイドル状態が続いているものと判断し、アイドル回転数の目標値を上げることにより充電不足が防止される。バッテリ電圧のばらつきがそのしきい値以下であってもバッテリ電圧の平均値がそのしきい値よりも高いとき交通が良好に流れ過大な電気負荷もなくバッテリの充電が十分に行い得る状態と判断し、アイドル回転数の目標値を下げることによりバッテリの過充電や液減りが防止されエンジン負荷が軽減され燃費が向上する。
【００１０】
請求項３記載の発明では、上記アイドル回転数設定手段を、上記アイドル回転数の目標値の一回ごとの増減補正量を一定量とし、上記調整電圧設定手段を、調整電圧の下げ補正をアイドル回転数の目標値が所定値以下のときにのみ行うように設定する。
【００１１】
上記アイドル回転数の目標値の一回ごとの増減補正量を一定量とすることでアイドル回転数が急変しない。また上記アイドル回転数の目標値が所定値以下に達してから調整電圧の下げ補正が行われるから、エンジン負荷が急変しない。しかして走行中に調整電圧やアイドル回転数が変更されても運転者の受ける違和感が解消される。
【００１２】
【発明の実施の形態】
本発明の車両用充電制御装置の説明に先立ち発明者等の得た知見について説明する。発明者等は走行状態（例えば平均車速）および電気負荷と、所定時間におけるバッテリ電圧のばらつきたる標準偏差の関係を測定した。その結果、図４に示すようにバッテリ電圧の標準偏差は、平均車速が大きいほど、電気負荷が小さいほど小さく、一方平均車速が低いほど、電気負荷が大きいほど大きいことが分かった。これは平均車速が低いほど、電気負荷が大きいほど充電の要請に比して充電不足傾向となって充電が十分に行い得ないためバッテリ電圧が変動するのに対し、平均車速が大きいほど、電気負荷が小さいほど充電の要請に比して十分充電を行い得る状態にありバッテリ電圧が変動しないものと認められる。本発明はかかる知見を調整電圧等の適正化に応用したものである。
【００１３】
図１に本発明の車両用充電制御装置を用いたバッテリ充電システムの構成図を示す。このシステムは車両のエンジンルーム内に設置される。バッテリ１０の充電を制御する車両用充電制御装置はレギュレータ２０、エンジン制御ＥＣＵ３０により構成され、バッテリ電圧が調整電圧になるようにレギュレータ２０がオルタネータ４０を制御するとともに、エンジン制御ＥＣＵ３０が図略のエンジンの制御をするようになっている。
【００１４】
レギュレータ２０はオルタネータ４０に装着されており、スイッチング素子としてのスイッチングトランジスタ２１がこれに直列に接続されたフィールドコイル４１の導通と遮断とを行う一般的な構成で、スイッチングトランジスタ２１の制御を行うコンパレータ２２と充電制御ＥＣＵ２３とを備えている。
【００１５】
２入力の電圧比較手段であるコンパレータ２２は、これより出力される二値信号がレギュレータ２０のスイッチングトランジスタ２１をオンオフするようになっている。コンパレータ２２は、その＋入力端子にはバッテリ１０電圧が入力し、−入力端子には充電制御ＥＣＵ２３から調整電圧が入力しており、スイッチングトランジスタ２１に出力される二値信号はバッテリ１０電圧と調整電圧の比較により与えられる。
【００１６】
充電制御ＥＣＵ２３は、ＣＰＵ２３ａ、メモリ２３ｂ等を備える一般的なマイクロコンピュータであり、これにバッテリ１０の電圧が入力し、バッテリ電圧について所定時間における平均値（以下、バッテリ平均電圧）とばらつきたる標準偏差とを演算し、これら演算結果に基づいて調整電圧およびアイドル回転数の目標値の設定を行うようになっている。
【００１７】
エンジン制御ＥＣＵ３０には充電制御ＥＣＵ２３で設定されたアイドル回転数の目標値が入力し、エンジン制御ＥＣＵ３０がエンジンのアイドル回転数を目標値に調整するようになっている。
【００１８】
上記車両用充電制御装置の作動を説明する。図２は充電制御ＥＣＵ２３のＣＰＵ２３ａの処理フローで、車両のイグニションキー（以下、ＩＧキー）がオンされると開始する。まずステップＳ１でカウンターｉと、所定時間におけるバッテリ平均電圧〈Ｖ〉および標準偏差ｓの算出に利用するｔ，ｔ’とを「０」に初期化する。ｔは所定時間に読み込まれたバッテリ電圧の和を算出するための変数で、ｔ’は所定時間に読み込まれたバッテリ電圧の二乗和を算出するための変数である。また調整電圧Ｖｍを１４．２Ｖ、アイドル回転数の目標値Ｎａを所定値たる最低回転数、例えば５５０ｒｐｍに設定する。
【００１９】
ステップＳ２〜Ｓ５はばらつき演算手段および平均値演算手段としての作動で、ステップＳ２では、１秒ごとにバッテリ電圧Ｖｉを読み込むとともにカウンターｉを１増やす。
【００２０】
ステップＳ３では、カウンターｉを所定時間、ここでは２００秒で除したときの余りが「０」かどうかを判定する。これにより２００秒経過したか経過前かが知られ、余りが「０」でない場合すなわち２００秒経過前はステップＳ４に進み、変数ｔをｔ＋Ｖｉに、変数ｔ’をｔ’＋Ｖｉ ^２に更新してステップＳ１６に進み、ＩＧキーがオフしていなければステップＳ２に戻る。しかしてステップＳ４において１秒間隔で読み込まれたＶｉ，Ｖｉ ^２が積算される。
【００２１】
ステップＳ３において余りが「０」になると、すなわち２００秒経過するとステップＳ３からステップＳ５に進む。ステップＳ５では２００秒間におけるＶｉの和（ｔ）を式（１）に代入してバッテリ平均電圧〈Ｖ〉を算出し、これとＶｉの二乗和（ｔ’）とを式（２）に代入して２００秒間におけるバッテリ電圧の標準偏差ｓを算出する。
【００２２】
【数１】

【００２３】
ステップＳ６〜Ｓ１４は調整電圧設定手段およびアイドル回転数設定手段としての作動で、２００秒間におけるバッテリ平均電圧〈Ｖ〉と標準偏差ｓとに基づき調整電圧Ｖｍ、アイドル回転数目標値Ｎａの設定を行う。
【００２４】
ステップＳ６では標準偏差ｓの値を所定のしきい値例えば０．３５と比較する。このしきい値は、車速や電気負荷等が異なる種々の実走行状態においてバッテリ電圧を測定して各状態下におけるバッテリ電圧の標準偏差を演算し、車速や電気負荷等からバッテリ１０の充電が十分行い得ると認められる状態と充電が十分行い得ないと認められる状態とを分類する標準偏差の値に設定する。標準偏差ｓが０．３５よりも大きければ充電が十分行い得ない状態と判断して調整電圧Ｖｍを高めの１４．２Ｖにし（ステップＳ７）、アイドル回転数の目標値Ｎａを５０ｒｐｍ増加する（ステップＳ８）。続くステップＳ９ではアイドル回転数の目標値Ｎａを上限値以下に抑える上限補正を行う。すなわちステップＳ８において補正されたアイドル回転数の目標値Ｎａが最大回転数、例えば８００ｒｐｍよりも大きい場合には、目標値Ｎａを８００ｒｐｍとする。このステップＳ７〜Ｓ９により充電が促進され充電不足が防止される。
【００２５】
かかる調整電圧Ｖｍおよびアイドル回転数の目標値Ｎａの補正の後はｔ，ｔ’を「０」にリセットして（ステップ１５）次の２００秒間に備え、ステップ１６に進む。
【００２６】
ステップＳ６において標準偏差ｓの値が０．３５よりも小さければ十分充電を行い得る状態と判断しステップＳ１０に進む。ステップＳ１０はステップＳ５において演算されたバッテリ平均電圧〈Ｖ〉を所定のしきい値、例えば１３Ｖと比較する。このしきい値はバッテリ１０の内部起電圧以上であればよいが、望ましくは本実施形態のように内部起電圧よりも若干高めに設定しておく。バッテリ平均電圧〈Ｖ〉が１３Ｖよりも低ければ、バッテリ電圧の変動が小さいが充電量が少ない状態すなわちアイドリング状態と判断し、上記ステップＳ８に進みアイドル回転数の目標値Ｎａを増加する。これによりバッテリ１０の充電不足が防止される。
【００２７】
なおステップＳ１０においてバッテリ平均電圧〈Ｖ〉が１３Ｖよりも高ければ充電が十分に行い得る状態すなわち比較的交通の流れがよく電気負荷も過大なものではない状態と判断しステップＳ１１に進む。
【００２８】
ステップＳ１１ではアイドル回転数の目標値Ｎａが最低回転数（ここでは５５０ｒｐｍ）と等しいかどうかを判定する。等しくない場合、すなわちアイドル回転数の目標値Ｎａが最低回転数よりも高ければステップＳ１２に進みアイドル回転数の目標値Ｎａを５０ｒｐｍ減少せしめてステップＳ１３に進む。ステップＳ１３ではアイドル回転数の目標値Ｎａを下限値以上に保つ下限補正を行う。すなわちステップＳ１２において補正されたアイドル回転数の目標値Ｎａが最低回転数５５０ｒｐｍよりも小さい場合には、目標値Ｎａを５５０ｒｐｍとする。かかるステップＳ１２，Ｓ１３によりバッテリ１０の過充電や液減りが防止されるとともにエンジン負荷が軽減し燃費が向上する。
【００２９】
ステップＳ１１においてアイドル回転数の目標値Ｎａが最低回転数のときはステップＳ１４に進み調整電圧Ｖｍを低めの１３．５Ｖとする。これによりバッテリ１０の過充電や液減りが防止されるとともにエンジン負荷が軽減し燃費が向上する。
【００３０】
なおアイドル回転数の目標値Ｎａの下げ補正（ステップＳ１２）と調整電圧Ｖｍの下げ補正（ステップＳ１４）とは、上記ステップＳ１１〜Ｓ１４の手順より知られるごとくアイドル回転数の目標値Ｎａの下げ補正（ステップＳ１２）が段階的に行われて徐々にアイドル回転数の目標値Ｎａが低下し、最低回転数５５０ｒｐｍに下がってから調整電圧Ｖｍの下げ補正（ステップＳ１４）が行われる。かかる手順とするのは、アイドル回転数の目標値Ｎａが急変した場合や、高アイドル回転数の下における調整電圧Ｖｍの変更でエンジン負荷が急変した場合に運転者が違和感を覚えるため、これを避けていわゆるドライバビリティを向上せしめるためである。
【００３１】
アイドル回転数の目標値Ｎａの下限補正（ステップＳ１３）、調整電圧Ｖｍの下げ補正（ステップＳ１４）の後はステップＳ１５からステップＳ１６に進む。
【００３２】
なおＩＧキーがオフされると（ステップＳ１６）本ルーチンは終了する。
【００３３】
図３は実際のバッテリ電圧の経時変化の一例を示し、図３（Ａ）は渋滞走行時のもので電気負荷が中負荷（４０Ａ相当）である。このときの標準偏差ｓは０．６６０（＞０．３５）であった。かかる場合には、本発明によれば充電が十分に行い得ない状態と判断され調整電圧Ｖｍが高く設定され、アイドル回転数の目標値Ｎａが増加されて、充電が促進される。これにより過放電が防止される。
【００３４】
一方、図３（Ｂ）は高速走行時のもので電気負荷が常用負荷（１０Ａ相当）である。このときの標準偏差ｓは０．００３（＜０．３５）であった。かかる場合には、本発明によればバッテリ平均電圧も１４．２０Ｖと高く充電が十分に行い得る状態と判断され調整電圧Ｖｍが低く設定され、アイドル回転数の目標値Ｎａが減じられ、充電が抑制される。これにより過充電が防止され燃費が向上する。
【００３５】
なお本実施形態では調整電圧Ｖｍはバッテリ電圧の標準偏差ｓにより二値をとるようにしたが、バッテリ電圧の標準偏差ｓに応じてさらに細かく異なる値をとるようにしてもよい。
【００３６】
アイドル回転数の目標値Ｎａの１回ごとの増減量は一定量とするのではなくバッテリ電圧の標準偏差ｓの大きさに応じて設定し、バッテリの充電が十分に行い得ない状態に迅速に対処するようにしてもよい。
【００３７】
装置の構成を簡単にするにはアイドル回転数の目標値の補正を省略して調整電圧のみの補正としてもよいし、所定時間におけるバッテリ電圧のばらつきとして標準偏差に代えて所定時間におけるバッテリ電圧の最大値と最小値の偏差を用いることもできる。
【００３８】
またエンジン制御ＥＣＵと充電制御ＥＣＵとは別体とするのではなく、統合して１つのＥＣＵとしてもよい。
【図面の簡単な説明】
【図１】本発明の車両用充電制御装置の構成図である。
【図２】本発明の車両用充電制御装置の作動を説明するフローチャートである。
【図３】（Ａ），（Ｂ）は本発明の車両用充電制御装置の作動を説明する第１、第２のグラフである。
【図４】本発明の発明者らが得た知見を説明するグラフである。
【符号の説明】
１０バッテリ
２０レギュレータ
２３充電制御ＥＣＵ
２３ａＣＰＵ（調整電圧設定手段、ばらつき演算手段、平均値演算手段、アイドル回転数設定手段）
３０エンジン制御ＥＣＵ
４０オルタネータ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a vehicle charge control device that controls charging of a battery mounted on a vehicle.
[0002]
[Prior art]
In the vehicle charge control device, the field current of the alternator is controlled by a regulator so that the battery voltage becomes the regulated voltage. In the current vehicle charge control device, the adjustment voltage is set higher (about 13.5 to 14.5 V) than the rated voltage (for example, 12 V) of the battery in order to charge the battery efficiently. However, when the electric load is low in a high-speed running state, the vehicle tends to be overcharged, increasing the load on the engine, deteriorating the fuel consumption, and promoting the reduction of the battery fluid. Therefore, in the vehicle storage battery charging system described in Japanese Patent Application Laid-Open No. Sho 62-37025, the battery voltage is detected, and when the battery voltage falls below a predetermined value, it is determined that the battery is overdischarged and the adjustment voltage is set high to improve the charge acceptability. When the detected battery voltage is higher than a predetermined value, it is determined that the battery is overcharged, and the adjustment voltage is set low to suppress the charge acceptability.
[0003]
[Problems to be solved by the invention]
By the way, in the vehicle battery charging system described in Japanese Patent Application Laid-Open No. Sho 62-37025, the adjustment voltage is set low if the battery is near full charge and the battery voltage is high. However, the battery voltage is detected higher than usual due to the influence of charge polarization even during idling when the battery is in the battery discharge state, so if the vehicle continues to run at high load and at low speed, the adjustment voltage is set high until the battery reaches overdischarge There is a possibility that the battery may be insufficiently charged and the required battery level at the time of restarting the engine may not be secured.
[0004]
Also, even if traffic flows relatively well and the battery voltage is high on average, the battery cannot be charged sufficiently if the electric load is excessive, and in such a case, setting the adjustment voltage low will result in insufficient charging. There is a risk that it will.
[0005]
Therefore, in the present invention, appropriate charging control is performed with a simple configuration in accordance with the running state of the vehicle and the state of the electric load, thereby preventing deterioration of fuel efficiency and battery drain due to overcharging, and also preventing insufficient battery charging. It is an object of the present invention to provide a vehicular charge control device that can perform the charging.
[0006]
[Means for Solving the Problems]
The inventors have found that the lower the electric load, the higher the vehicle speed, that is, the state in which the battery can be sufficiently charged, the smaller the variation in the battery voltage. On the other hand, the higher the electric load, the lower the vehicle speed, that is, the more the battery charge, It has been found that the more the battery cannot be operated, the greater the variation in battery voltage. The present invention has been made based on such knowledge, and in the invention according to claim 1, a vehicle charging control device including a regulator for controlling an alternator so that a battery voltage becomes a preset adjustment voltage is provided for a predetermined time. And an adjustment voltage setting means for setting the adjustment voltage to be lower as the variation of the battery voltage calculated by the variation calculation means is smaller.
[0007]
It can be determined that the smaller the variation in the battery voltage, the more the battery can be charged. Therefore, by setting the adjustment voltage low, overcharging and fluid reduction of the battery are prevented, the engine load is reduced, and fuel efficiency is improved. Conversely, it can be determined that the greater the variation in the battery voltage, the more the battery cannot be charged. Therefore, by setting the adjustment voltage high, insufficient charging is prevented.
[0008]
According to the present invention, the average value of the battery voltage during the predetermined time is calculated by the average value calculating means together with the variation of the battery voltage, and the idle speed setting means increases or decreases the idle speed based on the result. And
[0009]
The idle speed setting means compares the variation of the battery voltage and the average value of the battery voltage with the respective predetermined threshold values, and if the variation of the battery voltage is equal to or more than the threshold value, the battery is sufficiently charged. It is determined that the state cannot be obtained, and the target value of the idle speed is increased to prevent insufficient charging. When the variation of the battery voltage is equal to or less than the threshold value and the average value of the battery voltage is lower than the threshold value, it is determined that the idle state where the charge amount is small continues, and the target value of the idle speed is set. Raising prevents a shortage of charge. If the average of the battery voltage is higher than the threshold even if the variation of the battery voltage is equal to or less than the threshold, it is determined that the traffic is good and the battery can be sufficiently charged without an excessive electric load. However, by lowering the target value of the idle speed, overcharging of the battery and reduction of the liquid level are prevented, engine load is reduced, and fuel efficiency is improved.
[0010]
According to the third aspect of the present invention, the idle speed setting means sets the amount of increase / decrease correction for each time the target value of the idle speed to a fixed amount, and the adjustment voltage setting means sets the idle voltage to the correction value for adjusting the reduction of the adjustment voltage. It is set to be performed only when the target value of the rotation speed is equal to or less than a predetermined value.
[0011]
The idling speed does not suddenly change by setting the amount of increase / decrease correction for each time of the target value of the idling speed to be constant. In addition, since the correction of the adjustment voltage is corrected after the target value of the idling speed has reached the predetermined value or less, the engine load does not suddenly change. Thus, even if the adjustment voltage or the idling speed is changed during traveling, the uncomfortable feeling experienced by the driver is eliminated.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Prior to describing the vehicle charging control device of the present invention, knowledge obtained by the inventors will be described. The inventors measured the relationship between the running state (for example, the average vehicle speed) and the electric load, and the standard deviation of the battery voltage during a predetermined time. As a result, as shown in FIG. 4, it was found that the standard deviation of the battery voltage was smaller as the average vehicle speed was larger and the electric load was smaller, while it was larger as the average vehicle speed was lower and the electric load was larger. This is because the lower the average vehicle speed and the higher the electric load, the lower the tendency of charging compared to the request for charging and the charging cannot be performed sufficiently, so that the battery voltage fluctuates. It is recognized that the smaller the load, the more the battery can be charged compared to the request for charging and the battery voltage does not fluctuate. The present invention applies such knowledge to the adjustment of the adjustment voltage and the like.
[0013]
FIG. 1 shows a configuration diagram of a battery charging system using the vehicle charging control device of the present invention. This system is installed in the engine room of the vehicle. The vehicle charge control device that controls charging of the battery 10 includes a regulator 20 and an engine control ECU 30. The regulator 20 controls the alternator 40 so that the battery voltage becomes the regulated voltage, and the engine control ECU 30 controls the engine engine (not shown). Control.
[0014]
The regulator 20 is mounted on the alternator 40, and has a general configuration in which a switching transistor 21 as a switching element turns on and off a field coil 41 connected in series with the alternator 40. A comparator that controls the switching transistor 21 is provided. 22 and a charge control ECU 23.
[0015]
The comparator 22 serving as a two-input voltage comparing means is configured such that a binary signal output from the comparator 22 turns on and off the switching transistor 21 of the regulator 20. The comparator 22 has a + input terminal to which the voltage of the battery 10 is input, a − input terminal to which an adjustment voltage is input from the charge control ECU 23, and a binary signal output to the switching transistor 21 being adjusted to the battery 10 voltage. Given by voltage comparison.
[0016]
The charge control ECU 23 is a general microcomputer including a CPU 23a, a memory 23b, and the like. The voltage of the battery 10 is input to the microcomputer, and the standard deviation of the battery voltage varies from an average value for a predetermined time (hereinafter, battery average voltage). Are calculated, and the target values of the adjustment voltage and the idle speed are set based on the calculation results.
[0017]
The target value of the idling speed set by the charging control ECU 23 is input to the engine control ECU 30, and the engine control ECU 30 adjusts the idling speed of the engine to the target value.
[0018]
The operation of the vehicle charging control device will be described. FIG. 2 is a processing flow of the CPU 23a of the charge control ECU 23, which is started when an ignition key (hereinafter, IG key) of the vehicle is turned on. First, in step S1, a counter i and t and t 'used for calculating a battery average voltage <V> and a standard deviation s during a predetermined time are initialized to "0". t is a variable for calculating the sum of the battery voltages read at a predetermined time, and t ′ is a variable for calculating the sum of squares of the battery voltage read at a predetermined time. Further, the adjustment voltage Vm is set to 14.2 V, and the idle speed target value Na is set to a predetermined minimum speed, for example, 550 rpm.
[0019]
Steps S2 to S5 are operations as the variation calculation means and the average value calculation means. In step S2, the battery voltage Vi is read every second and the counter i is increased by one.
[0020]
In step S3, it is determined whether the remainder obtained by dividing the counter i by a predetermined time, here, 200 seconds, is “0”. Or prior to the expiration or was thereby passed 200 seconds is known, is prior to the expiration case that is 200 seconds, the remainder is not "0", the flow proceeds to step S4, the variable t to t + Vi, by updating 'the t' variable t to + Vi ² The process proceeds to step S16, and if the IG key is not turned off, the process returns to step S2. Thus read at one second intervals in step S4 Vi, Vi ² is integrated.
[0021]
When the remainder becomes “0” in step S3, that is, when 200 seconds have elapsed, the process proceeds from step S3 to step S5. In step S5, the sum (t) of Vi for 200 seconds is substituted into equation (1) to calculate the battery average voltage <V>, and this and the sum of squares of Vi (t ') are substituted into equation (2). To calculate the standard deviation s of the battery voltage for 200 seconds.
[0022]
(Equation 1)

[0023]
Steps S6 to S14 are operations as the adjustment voltage setting means and the idle speed setting means, and set the adjustment voltage Vm and the idle speed target value Na based on the battery average voltage <V> and the standard deviation s for 200 seconds. .
[0024]
In step S6, the value of the standard deviation s is compared with a predetermined threshold value, for example, 0.35. This threshold value is obtained by measuring the battery voltage in various actual running states having different vehicle speeds, electric loads, and the like, calculating the standard deviation of the battery voltage in each state, and sufficiently charging the battery 10 based on the vehicle speed, the electric load, and the like. The value is set to the value of the standard deviation which classifies a state recognized as being able to be performed and a state recognized as being unable to perform charging sufficiently. If the standard deviation s is larger than 0.35, it is determined that charging cannot be performed sufficiently, and the adjustment voltage Vm is increased to 14.2 V (step S7), and the target value Na of the idle speed is increased by 50 rpm (step S7). S8). In a succeeding step S9, an upper limit correction for keeping the target value Na of the idling rotational speed below the upper limit value is performed. That is, when the target value Na 2 of the idle speed corrected in step S8 is larger than the maximum speed, for example, 800 rpm, the target value Na 2 is set to 800 rpm. By these steps S7 to S9, charging is promoted and insufficient charging is prevented.
[0025]
After the correction of the adjustment voltage Vm and the target value Na of the idle speed, t and t 'are reset to "0" (step 15), and the process proceeds to step 16 in preparation for the next 200 seconds.
[0026]
If the value of the standard deviation s is smaller than 0.35 in step S6, it is determined that the battery can be charged sufficiently, and the process proceeds to step S10. In step S10, the average battery voltage <V> calculated in step S5 is compared with a predetermined threshold value, for example, 13V. The threshold value may be equal to or higher than the internal electromotive voltage of the battery 10, but is desirably set slightly higher than the internal electromotive voltage as in the present embodiment. If the battery average voltage <V> is lower than 13 V, it is determined that the battery voltage fluctuation is small but the charge amount is small, that is, the idling state, and the process proceeds to step S8 to increase the target value Na of the idle speed. This prevents the battery 10 from being insufficiently charged.
[0027]
If the average battery voltage <V> is higher than 13 V in step S10, it is determined that charging can be sufficiently performed, that is, the flow of traffic is relatively high and the electric load is not excessive, and the process proceeds to step S11.
[0028]
In step S11, it is determined whether or not the idle speed target value Na is equal to the minimum speed (here, 550 rpm). If they are not equal, that is, if the idle speed target value Na is higher than the minimum rotation speed, the process proceeds to step S12, in which the idle speed target value Na is reduced by 50 rpm, and the process proceeds to step S13. In step S13, a lower limit correction for maintaining the target value Na of the idle speed at or above the lower limit is performed. That is, when the target value Na 2 of the idle speed corrected in step S12 is smaller than the minimum speed 550 rpm, the target value Na 2 is set to 550 rpm. By these steps S12 and S13, overcharging and liquid reduction of the battery 10 are prevented, the engine load is reduced, and fuel efficiency is improved.
[0029]
When the target value Na of the idle speed is the minimum speed in step S11, the process proceeds to step S14, and the adjustment voltage Vm is set to a lower value of 13.5V. As a result, overcharging and liquid reduction of the battery 10 are prevented, the engine load is reduced, and fuel efficiency is improved.
[0030]
Note that the lowering correction of the idle speed target value Na 2 (step S12) and the lowering correction of the adjustment voltage Vm (step S14) include the lowering correction of the idle speed target value Na 2 as is known from the procedures of steps S11 to S14. (Step S12) is performed in a stepwise manner, and the idle speed target value Na gradually decreases, and after decreasing to the minimum rotation speed of 550 rpm, the adjustment correction of the adjustment voltage Vm is performed (step S14). Such a procedure is used because the driver may feel uncomfortable when the target value Na of the idle speed suddenly changes or when the engine load suddenly changes due to the change of the adjustment voltage Vm under the high idle speed. This is to avoid so-called drivability.
[0031]
After the lower limit correction of the idle speed target value Na 1 (step S13) and the correction of the adjustment voltage Vm lowering (step S14), the process proceeds from step S15 to step S16.
[0032]
When the IG key is turned off (step S16), this routine ends.
[0033]
FIG. 3 shows an example of the actual change over time of the battery voltage. FIG. 3A shows a state during traffic congestion, and the electric load is a medium load (equivalent to 40 A). The standard deviation s at this time was 0.660 (> 0.35). In such a case, according to the present invention, it is determined that charging cannot be performed sufficiently, the adjustment voltage Vm is set high, the target value Na of the idle speed is increased, and the charging is promoted. This prevents overdischarge.
[0034]
On the other hand, FIG. 3B shows a case where the vehicle is running at a high speed and the electric load is a normal load (corresponding to 10 A). The standard deviation s at this time was 0.003 (<0.35). In such a case, according to the present invention, it is determined that the battery average voltage is as high as 14.20 V and charging can be sufficiently performed, the adjustment voltage Vm is set low, the target value Na of the idle speed is reduced, and the charging is performed. Be suppressed. This prevents overcharging and improves fuel efficiency.
[0035]
In the present embodiment, the adjustment voltage Vm takes two values according to the standard deviation s of the battery voltage. However, the adjustment voltage Vm may take a more minutely different value according to the standard deviation s of the battery voltage.
[0036]
The amount of increase / decrease of the target value Na of the idle speed at each time is set not according to the constant amount but according to the magnitude of the standard deviation s of the battery voltage. You may make it cope.
[0037]
In order to simplify the configuration of the apparatus, the correction of the target value of the idle speed may be omitted and the correction of only the adjustment voltage may be performed. The deviation between the maximum and minimum values can also be used.
[0038]
Further, the engine control ECU and the charge control ECU may be integrated into one ECU, instead of being formed separately.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a vehicle charging control device of the present invention.
FIG. 2 is a flowchart illustrating the operation of the vehicle charging control device according to the present invention.
FIGS. 3A and 3B are first and second graphs for explaining the operation of the vehicle charging control device of the present invention.
FIG. 4 is a graph illustrating the findings obtained by the inventors of the present invention.
[Explanation of symbols]
10 Battery 20 Regulator 23 Charge control ECU
23a CPU (adjustment voltage setting means, variation calculation means, average value calculation means, idle speed setting means)
30 Engine control ECU
40 alternator

Claims

In a vehicle charging control device including a regulator that controls an alternator that generates power by an engine driving force to charge a vehicle-mounted battery so that the battery voltage becomes a preset adjustment voltage, the variation of the battery voltage in a predetermined time is reduced. A charge control device for a vehicle, comprising: a variation calculation means for calculating; and an adjustment voltage setting means for setting the adjustment voltage to be lower as the variation in the battery voltage calculated by the variation calculation means is smaller.

2. The vehicle charge control device according to claim 1, wherein an average value calculating means for calculating an average value of the battery voltage during the predetermined time, and the variation of the battery voltage calculated by the variation calculating means is set to a predetermined threshold value. Comparing the average value of the battery voltage calculated by the average value calculation means with the predetermined threshold value, and when the variation of the battery voltage is larger than the threshold value and when the variation of the battery voltage is larger than the threshold value. The idle speed target value is increased either when the average value of the battery voltage is smaller than the threshold value and the average value of the battery voltage is smaller than the threshold value. Vehicle charging provided with idle speed setting means for lowering the target value of the idle speed when the value is larger than the threshold value Control device.

3. The charge control device for a vehicle according to claim 2, wherein the idle speed setting means sets the amount of increase / decrease correction for each time of the target value of the idle speed to a fixed amount, and the adjustment voltage setting means adjusts the adjustment voltage. A charge control device for a vehicle, wherein a reduction correction is performed only when a target value of an idle speed is equal to or less than a predetermined value.