JP3922100B2 - Actuator for drive switching device - Google Patents

Description

表１に示すように４つの端子ａ、ｂ、ｃ、ｄの接触状態が変化することでリミットスイッチ３６の設定位置Ｉ〜Ｖを検出し、更に設定位置がＩ〜Ｖのどの位置にあるかによって車両の駆動状態の設定位置Ａ〜Ｃ、及びそれらの中間位置が検出される。ここで、設定位置Ａは２輪駆動、設定位置Ｂは４輪駆動（センターデフフリー）、設定位置Ｃは４輪駆動（センターデフロック）に対応するロッド３３の軸方向位置を示している。尚、リミットスイッチ３６の端子ａはアースであり、常時接触している。
【００１９】
アクチュエータ部３０とともに駆動切換装置用アクチュエータを構成する制御機構４０について説明する。制御機構４０は、バッテリーＢＡＴから供給される電圧を所定の駆動電圧に変換する電源回路４８と、モータ３１に流れる電流を検出する電流検出回路４５と、電源回路４８とモータ３１との間に配設されモータ３１の通電・非通電を切替可能な通電切替回路４２と、電流検出回路４５が検出する電流に基づいてモータ３１を駆動するべく、通電切替回路４２を作動する演算処理装置としてのＣＰＵ４１を備えている。
【００２０】
通電切替回路４２は、リレー４３Ａ、４３Ｂとスイッチングパワー素子であるＦＥＴ４４を有しており、リレー４３ＡとＦＥＴ４４とが共にオン、或いはリレー４３ＢとＦＥＴ４４とが共にオンのときにのみモータ３１が通電し、リレー４３ＡとＦＥＴ４４の少なくともいずれかがオフのとき、或いはリレー４３ＢとＦＥＴ４４の少なくともいずれかがオフのときにはモータ３１が非通電となるようにリレー４３Ａ、４３ＢとＦＥＴ４４とが配設されている。本実施の形態では、通電切換回路４２は２つのリレー４３Ａ、４３Ｂを有しているが、これは、モータ３１を正転方向に回転させるときにオンするリレー４３Ａと、モータ３１を逆転方向に回転させるときにオンするリレー４３Ｂであり、駆動状態の切替時に２つのリレー４３Ａ、４３Ｂが同時にオンすることはない。また、ＦＥＴ４４はモータ３１とアースとの間に設けられることにより、１つのＦＥＴで２つのリレー４３Ａ、４３Ｂに対応した構造となっている。尚、図４に示す構成以外にも、リレー４３Ａとリレー４３ＢとでそれぞれのＦＥＴが対応するようにＦＥＴを２個配設してもよい。
【００２１】
電流検出回路４５は、抵抗４７に流れる電流をオペアンプ４６にて基準電流値Ｉ０、第１所定電流値Ｉ１、第２所定電流値Ｉ２と比較することで、モータ３１に流れる電流がこれら電流値に達しているか否かを検知している。尚、基準電流値Ｉ０は、ＣＰＵ４１が検出可能な電流のうち最も小さな値である。
【００２２】
ＣＰＵ４１は、電源回路４８、車速、手動スイッチ５０のオン・オフ、リミットスイッチ３６の各端子ｂ、ｃ、ｄの接触・非接触、及び電流検出回路が検出する電流を入力して、これら入力された信号に応じた駆動状態となるようにモータ３１の回転方向及び通電電流を算出し、この算出された回転方向及び電流値を出力すべくリレー４３Ａ、４３Ｂ及びＦＥＴ４４のオン・オフを出力する。モータ３１に流れる電流に関しては、抵抗４７に流れる電流をオペアンプ４６にて各電流値と比較することで、モータ３１に流れる電流が基準電流値Ｉ０、第１所定電流値Ｉ１、或いは第２所定電流値Ｉ２に達しているか否かを検知している。
【００２３】
駆動切替装置用アクチュエータの故障の検出について、図５のフローチャートを用いて説明する。電源回路４８からＣＰＵ４１に電圧が供給されてイグニッションスイッチＩＧがオンされると図５のフローチャートがスタートする。先ず、ステップＳ１０でリレー４３Ａをオンするとともにリレー４３Ｂをオフする。そしてステップＳ１１にてＦＥＴ４４をオフする。次に、ステップＳ１２に進んでモータ３１に流れる電流Ｉが基準電流値Ｉ０より大きいか否かを判断する。ＦＥＴ４４がＣＰＵ４１の指示通りにオフされていればモータ３１には電流が流れないので、ＦＥＴ４４がオン故障していない限り電流Ｉは基準電流値Ｉ０より大きくならない。ＦＥＴ４４がオン故障しておらず、ステップＳ１２で電流Ｉが基準電流値Ｉ０以下であると判断された場合にはステップＳ１３に進み、リレー４３Ａをオフするとともにリレー４３Ｂをオンする。そして、ステップＳ１４にて、ステップＳ１２と同様に電流Ｉが基準電流値Ｉ０より大きいか否かを判断する。ステップＳ１４の実行時にはＦＥＴ４４がオフされているので、ＦＥＴ４４がオン故障していない限り電流Ｉは基準電流値Ｉ０より大きくならない。ＦＥＴ４４がオン故障しておらず、ステップＳ１４で電流Ｉが基準電流値Ｉ０以下であると判断された場合にはステップＳ１５に進む。
【００２４】
ステップＳ１６に進むとリレー４３Ａ、４３Ｂをともにオフし、ステップＳ１７にてＦＥＴ４４をオンする。そして、ステップＳ１７に進み、ステップＳ１２及びステップＳ１４と同様に電流Ｉが基準電流値Ｉ０より大きいか否かを判断する。ステップＳ１７の実行時にはリレー４３Ａ、４３Ｂがともにオフされているため、リレー４３Ａ或いはリレー４３Ｂのいずれかがオン故障していない限り、モータ３１に電流は流れない。リレー４３Ａ、４３Ｂがともにオン故障しておらず、ステップＳ１７で電流Ｉが基準電流値Ｉ０以下であると判断されると、ステップＳ１９に進んで後述する通常通電制御を実行する。
【００２５】
ここで、ＦＥＴ４４がオン故障している場合には、モータ３１に電流が流れてステップＳ１２にて電流Ｉが基準電流値Ｉ０より大きいと判断され、ステップＳ１８に進む。ＦＥＴ４４がオン故障している場合には、モータ３１に電流が流れてステップＳ１４にて電流Ｉが基準電流値Ｉ０より大きいと判断され、ステップＳ１８に進む。また、リレー４３Ａ、４３Ｂのいずれかがオン故障している場合にも、モータ３１に電流が流れてステップＳ１７にて電流Ｉが基準電流値Ｉ０より大きいと判断され、ＦＥＴ４４のオン故障時と同様にステップＳ１８に進む。ステップＳ１８では、運転者による駆動状態の切替要求があってもモータ３１に通電しないように、リレー４３Ａ、４３Ｂ及びＦＥＴ４４をオフする。そして、リレー４３Ａ、４３Ｂ或いはＦＥＴ４４がオン故障していることを運転者に知らせるべく、図示しないインジケータを点灯させる。
【００２６】
次に、ステップＳ１９の通常通電制御について、図６のフローチャート及び図７〜図１０のタイムチャートを用いて説明する。本実施の形態では、車両の駆動状態が４輪駆動（センターデフフリー）から４輪駆動（センターデフロック）へ切替わるときの各構成の作動を用いて説明する。図７および図９はモータ３１に流れる電流と時間、図８および図１０はロッド３３のストロークと時間の関係をそれぞれ示している。
【００２７】
制御がスタートすると、先ずステップＳ１００に進んで、駆動切替装置１０に切替の要求があったか否かを判断すべく、手動スイッチ５０がオンされたか否かを判定する。手動スイッチ５０がオンされたと判定されると、切替要求有りと判断してＹｅｓと判定されてステップＳ１１０に進んでＣＰＵ４１がリレー４３Ａ、４３Ｂ及びＦＥＴ４４のオン・オフ信号を出力し、モータ３１への通電を開始する（ｔ０）。
【００２８】
そして、ステップＳ１２０に進んで、モータ３１への通電開始によりモータ３１に流れる突入電流を意図的に抑える制御（突入制御）が完了したか否かを判断する。このステップＳ１２０では、実際にはステップＳ１１０でモータ３１への通電が開始されてから所定の時間（ｔ１）が経過したか否かを判定している。ステップＳ１２０は、時間（ｔ１）が経過するまで繰り返し処理される。
【００２９】
ステップＳ１２０でＹｅｓと判定されると、ステップＳ１３０に進んでモータ３１を常時通電する制御を実行する。ステップＳ１３０の常時通電が開始すると、安定した電流Ｉ２がモータ３１に流れて出力軸３１Ａが回転駆動し、出力機構３２を介してロッド３３が軸方向に変位する。時間ｔ０〜ｔ２まではロッド３３の軸方向の変位は規制されることなく時間に比例してロッド３３がストロークする。尚、時間ｔ０〜ｔ２の間でスパイラルスプリング３５Ｂに作用する荷重は各部材の摺動抵抗だけである。
【００３０】
次に、ステップＳ１４０にて、表１で示したリミットスイッチ３６の設定位置に基づいて、ロッド３３の移動が完了したか（ロッド３３が所望の位置に移動したか）否かを判定する。ここで、ロッド３３のストロークに伴うセンターデフロックシフトフォーク１７の軸方向の変位に際して、スリーブ１７Ａの内外周に形成されたスプラインとセンターデフユニット１３に形成されたスプラインとが噛合うと、センターデフユニット１３の遊星歯車機構が作用しないようにスリーブ１７Ａが遊星歯車機構を一体回転させてセンターデフロック状態となって、ロッド３３の移動が完了する。しかしながら、スリーブ１７Ａが軸方向に変位してもセンターデフフリーの状態では遊星歯車機構が作用しているためにスリーブ１７Ａの内外周に形成されたスプラインとセンターデフユニット１３に形成されたスプラインとは直ぐには噛合わず、スリーブ１７Ａのスプラインとセンターデフユニット１３のスプラインとが噛合ってロッド３３の移動が完了するまでは、スパイラルスプリング３５Ｂが弾縮した状態（以下、待ち状態と称す）を保持している。この待ち状態には、ロッド３３が軸方向に変位できない状態（第１状態）と、ロッド３３が所定の負荷を受けながら軸方向に変位する状態（第２状態）の２つの状態があり、これらの状態の下では、モータ３１に流れる電流値は徐々に大きくなる。
【００３１】
ロッド３３の移動が完了していないときにはステップＳ１４０でＮｏと判定されて、ステップＳ１５０に進む。ステップＳ１５０にて、モータ３１に流れる電流が第２所定電流値Ｉ２以上であるか否かが判定される。上述した第１状態或いは第２状態の下ではスプラインが正常に噛合っていないためモータ３１に負荷がかかり、モータ３１に流れる電流は第２所定電流値Ｉ２以上になる。尚、第２所定電流値Ｉ２は、スプラインが正常に噛合った状態でロッド３３が余分な負荷を受けることなく移動するときにモータ３１に流れる電流値Ｉｓよりも若干大きい電流値に設定されており、電流値Ｉｓは、時間ｔ１からｔ２の範囲においてモータ３１に流れる電流値と同等の値である。
【００３２】
モータ３１に流れる電流が第２所定電流値Ｉ２以上であると、ステップＳ１５０でＹｅｓと判定されて、ステップＳ１６０に進む。ステップＳ１６０では、モータ３１に流れる電流が第１所定電流値Ｉ１（Ｉ１＞Ｉ２）より小さいか否かが判定される。尚、第１所定電流値Ｉ１は、モータ３１への通電が行われているにもかかわらずスプラインが噛合わずにロッド３３がロック状態となってロッド３３が作動不可となる第１状態において、モータ３１に流れる電流値となるように設定されている。つまり、第１所定電流値Ｉ１は、モータ３１の出力軸３１Ａが回転できない状態でモータ３１への通電が制限されないとき（常時通電時）に、モータ３１を流れるであろうと推測される電流値である。
【００３３】
ステップＳ１６０においてモータ３１の電流が第１所定電流値Ｉ１以上である場合（図６の時間ｔ３）には、ステップＳ１６０にてＮｏと判定され、ステップＳ１８０へと進む。この場合には、スプラインが噛合わずにロッド３３がロック状態となってロッド３３が作動不可となる第１状態と判断される（図７の時間ｔ２からｔ５）。
【００３４】
ステップＳ１８０に進むと、モータ３１の発熱を抑えるべく、モータ３１の通電電流を制限する。ステップＳ１８０では、ＰＷＭ制御によりモータ３１に流れる電流を第３所定電流Ｉ３（Ｉ１＞Ｉ３＞Ｉ２）に設定するとともにＯＮ・ＯＦＦ制御により電流の通電・非通電を行うように設定されている。具体的には、一旦ステップＳ１８０が実行されると、ＰＷＭ制御にてモータ３１の電流を第３所定電流値Ｉ３とし、カウンタを１つインクリメントする。ステップＳ１８０が実行されるとステップＳ１４０に戻り、再びロッド３３の移動が完了したか否かを判定する。ステップＳ１８０の処理はロッド３３の移動が完了しないかぎり繰り返し実行され、カウンタの値がＮ１になるまでモータへの通電電流は第３所定電流値Ｉ３を維持し続ける。カウンタの値がＮ１になるとカウンタをクリアし、通電電流のＯＮ制御からＯＦＦ制御に切替わる。その後、ステップＳ１８０を実行するときにはモータ３１への通電を停止するとともにカウンタを１つインクリメントする。ロッド３３の移動が完了、或いはモータ３１に流れる電流の値が変化しないかぎり更にステップＳ１８０が繰り返し実行され、カウンタの値がＮ２になるまでモータへの通電は行われない。そして、カウンタの値がＮ２になるとカウンタをクリアし、電流のＯＦＦ制御から再びＯＮ制御に切替わる。このように、ロッド３３の移動が完了することなくステップＳ１８０が繰り返し（Ｎ１＋Ｎ２以上）実行されると、モータ３１への通電電流のＰＷＭ制御およびＯＮ・ＯＦＦ制御が行われて、過電流によるモータ３１の発熱を抑える。ここで、ステップＳ１８０の実行によって図６の時間ｔ３〜ｔ５であらわされるＰＷＭ制御及びＯＮ・ＯＦＦ制御を併せて間欠通電制御１と称する。尚、出力軸３１Ａはサイクロイドギヤ３４を介して回転吸収機構３５に連結されているので、モータ３１が非通電（ＯＦＦ制御中）になっても出力軸３１Ａが逆方向に回転することはなく、電流の通電・非通電のＯＮ・ＯＦＦ制御が可能になる。
【００３５】
ステップＳ１６０においてモータ３１の電流が第１所定電流値Ｉ１より小さい場合（図８の時間ｔ３）には、ステップＳ１６０でＹｅｓと判定され、ステップＳ１７０へと進む。ステップＳ１６０でＹｅｓと判定されたときには、モータ３１を流れる電流は第２所定電流値Ｉ２と第１所定電流値Ｉ１との間である。この場合には、ロッド３３は作動しているが、モータ３１の出力軸３１Ａには負荷がかかっている第２状態と判断される（図９の時間ｔ３からｔ４）。この第２状態は、例えば、スプラインが完全には噛合っていないがモータ３１の駆動により得られるロッド３３の推力によってゆっくりとスプラインが噛合っていく場合や、遊星歯車機構の作動により遊星歯車機構のスプラインの側面とロッド３３のスプラインの側面との摺接時の負荷が大きい場合などが考えられる。ステップＳ１７０では、ステップＳ１５０でＹｅｓと判定されてからの時間が、所定時間ｔｓ以上であるか否かを判定している。つまり、モータ３１が第２状態になってからの時間が所定時間ｔｓを経過したか否かを判定している。ステップＳ１７０における所定時間ｔｓは、モータ３１の第２状態が継続されたときのモータ３１の発熱量が、モータ３１の許容発熱量を越えない範囲となるようにあらかじめ設定されており、モータ３１に流れる電流の値に応じて設定されている。モータ３１が第２状態であるが所定時間ｔｓを越えていなければ、ステップＳ１７０にてＮｏと判定され、ステップＳ１３０に戻りモータ３１へ常時通電する。第２状態が所定時間ｔｓ以上継続されると（図８の時間ｔ４）、ステップＳ１７０にてＹｅｓと判定され、ステップＳ１９０に進む。
【００３６】
ステップＳ１９０に進むと、モータ３１の発熱を抑えるべく、モータ３１の通電電流を制限する。ステップＳ１９０では、ＰＷＭ制御によりモータ３１に流れる電流を第２所定電流Ｉ２に設定するとともにＯＮ・ＯＦＦ制御により電流の通電・非通電を行うように設定されている。具体的には、一旦ステップＳ１９０が実行されると、ＰＷＭ制御にて第２所定電流値Ｉ２を維持し、カウンタを１つインクリメントする。ステップＳ１９０が実行されるとステップＳ１４０に戻り、再びロッド３３の移動が完了したか否かを判定する。ステップＳ１９０の処理はロッド３３の移動が完了しないかぎり繰り返し実行され、カウンタの値がＮ３になるまでモータへの通電電流は第２所定電流値Ｉ２を維持し続ける。カウンタの値がＮ３になるとカウンタをクリアし、通電電流のＯＮ制御からＯＦＦ制御に切替わる。その後、ステップＳ１９０を実行するときにはモータ３１への通電を停止するとともにカウンタを１つインクリメントする。ロッド３３の移動が完了、或いはモータ３１に流れる電流の値が変化しないかぎり更にステップＳ１９０が繰り返し実行され、カウンタの値がＮ４になるまでモータへの通電は行われない。そして、カウンタの値がＮ４になるとカウンタをクリアし、電流のＯＦＦ制御から再びＯＮ制御に切替わる。このように、ロッド３３の移動が完了することなくステップＳ１９０が繰り返し（Ｎ３＋Ｎ４以上）実行されると、モータ３１への通電電流のＰＷＭ制御およびＯＮ・ＯＦＦ制御が行われて、過電流によるモータ３１の発熱を抑える。ここで、ステップＳ１９０の実行によって図８の時間ｔ４〜ｔ５であらわされるＰＷＭ制御及びＯＮ・ＯＦＦ制御を併せて間欠通電制御２と称する。
【００３７】
第１状態から間欠通電制御１を行った後にスリーブ１７Ａのスプラインとセンターデフユニット１３のスプラインとが噛合ってロッド３３が所望の位置に近づく、或いは第２状態から間欠通電制御２を行った後にロッド３３が徐々に動作して所望の位置に近づくと、スパイラルスプリング３５Ｂは弾縮状態から非弾縮状態に移行していくので、スパイラルスプリング３５Ｂの荷重が小さくなる。したがって、モータ３１の出力軸３１Ａにかかる負荷は小さくなり、モータ３１を流れる電流は第３所定電流値Ｉ３或いは第２所定電流値Ｉ２より小さくなる（図６および図８の時間ｔ５）。そしてモータ３１を常時通電する制御を実行（時間ｔ６）する。この状態で常時通電が開始されると安定した電流Ｉｓがモータ３１に流れて出力軸３１Ａが回転駆動し、スリーブ１７Ａがスプラインに沿って駆動状態の切替え完了の位置まで変位する（時間ｔ６からｔ７）。ロッド３３の移動が完了するとリミットスイッチ３６が所望の位置に切替えられるので、ステップＳ１４０にて、ロッド３３の移動が完全に完了したと判断されて、ステップＳ２２０に進んでモータ３１への通電を停止するとともに、本制御を一旦終了する。このように、上述した各ステップが実行されることで、モータ３１の発熱を抑えながら駆動切替装置の４輪駆動（センターデフフリー）から４輪駆動（センターデフロック）への切替えが完了する。
【００３８】
上述した実施の形態では、ＦＥＴ及びリレーのオン故障を検出してから通常通電制御を実行するようにしたが、本発明は、上述した実施形態に限定されるものではなく、これ以外にも以下のオン故障の検出が考えられる。一般的にスイッチング素子がオン・オフするのに要する時間は、リレーがオン・オフするのに要する時間に比べて非常に短い。したがって、例えば通常通電制御中に切替要求があった後、リレーがオンに移行するまでのリレーがオフとなっている間にスイッチング素子をオンすることで、リレーのオン故障を検出することができる。具体的には、ステップＳ１１０とステップＳ１２０との間に、ステップＳ１５からＳ１７の処理を実行するようにして達成される。これによると、駆動切替装置用アクチュエータの応答性を損なうことなく、且つ切替要求が有る度にリレーのオン故障を検出することができるので、好適である。
【００３９】
更に、例えばＦＥＴのオン故障を検出する際に、リレー４３Ａ、２を同時にオンするとともにＦＥＴをオフし、モータ３１に電流が流れていればＦＥＴのいずれかがオン故障していると判断するようにしてもよい。具体的にはステップＳ１０でリレー４３Ａ、２を同時にオンし、ステップＳ１３とステップＳ１４を省略することで達成される。これによると、ＦＥＴのオン故障の検出に要する処理が少なくなって、好適である。
【００４０】
【発明の効果】
本発明によると、駆動状態の切替時におけるモータの通電制御に用いられているリレーとＦＥＴのオン・オフを操作することで、新たに監視回路を設けることなくリレー或いはＦＥＴのオン故障を検出することができ、これらの故障の検出に際して部品点数が増加することがない。
【図面の簡単な説明】
【図１】本発明の実施の形態における駆動切換装置の断面図である。
【図２】本実施の形態における駆動切替用アクチュエータの断面図である。
【図３】図２のＡ視図である。
【図４】本実施の形態における制御機構の回路図である。
【図５】本実施の形態における制御機構による故障検出の処理を示すフローチャートである。
【図６】本実施の形態における制御機構による通常通電制御を示すフローチャートである。
【図７】本実施の形態における駆動切替用アクチュエータに係るタイムチャートである。
【図８】本実施の形態における駆動切替用アクチュエータに係るタイムチャートである。
【図９】本実施の形態における駆動切替用アクチュエータに係るタイムチャートである。
【図１０】本実施の形態における駆動切替用アクチュエータに係るタイムチャートである。
【符号の説明】
１０・・・駆動切替装置
３０・・・アクチュエータ部
３１・・・モータ
３２・・・出力機構
３３・・・ロッド（出力部材）
３４・・・サイクロイドギヤ（逆転禁止機構）
３５・・・回転吸収機構
３６・・・リミットスイッチ
４０・・・制御機構
４１・・・ＣＰＵ（演算処理装置）
４２・・・通電切替回路
４３Ａ、４３Ｂ・・・リレー
４４・・・ＦＥＴ（ＦＥＴ）
４５・・・電流検出回路
４８・・・電源回路
５０・・・手動スイッチ（切替要求検出機構）
ＢＡＴ・・・バッテリー[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an actuator of a drive switching device that switches the driving state of a vehicle from two-wheel drive to four-wheel drive or from four-wheel drive to two-wheel drive by controlling energization to a motor, and particularly to a motor. The present invention relates to the detection of a failure of the mechanism that controls the energization of the motor.
[0002]
[Prior art]
As a conventional actuator for a drive switching device, there is a technique disclosed in JP-A-8-223983. In this publication, a motor that generates an output torque corresponding to an energization current, a rod that reciprocates in the axial direction, and an output torque of the motor that is converted into axial thrust and transmitted to the rod, the motor is energized. A power transmission mechanism that reversely rotates the motor with a load on the rod when stopped, and energization of the motor for a predetermined time (1 second), and when a current exceeding the predetermined value flows to the motor, the current is PWM (pulse width modulation) ) Disclosed is a technology that employs a thrust actuator that includes a motor drive circuit that limits the energization current so that the output torque does not exceed a predetermined torque as an actuator for a switching device that switches between two-wheel drive and four-wheel drive. ing.
[0003]
According to this technology, the energization current flowing through the motor is limited and the output torque of the motor is suppressed, so that a large load is not applied to the rod and the power transmission mechanism, and the power transmission mechanism and components can be downsized. .
[0004]
[Problems to be solved by the invention]
In the drive wheel switching device actuator of the type disclosed in the above publication, when monitoring whether the relay and the power switching element in the motor drive circuit are normally turned on or off, when the motor is not energized The switching power element is on / off controlled at a predetermined timing, and the monitoring circuit determines whether or not the switching power element is normal.
[0005]
However, the above-described monitoring circuit is a circuit provided for determining whether or not the switching power element is normal, and there is a problem that the number of components increases by providing the monitoring circuit.
[0006]
Therefore, in order to solve the above problems, the present invention provides a drive switching device actuator that can determine whether or not a switching power element is normal without increasing the number of components as much as possible. And
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the invention of claim 1 is directed to a motor that is rotationally driven in accordance with an energization current, an output mechanism that outputs rotational torque of an output shaft of the motor, and rotation of the motor via the output mechanism. An output member capable of transmitting a thrust according to the torque and switching the driving state of the vehicle according to the displacement of the position; a switching request detecting mechanism for detecting whether or not there is a request to switch the driving state of the vehicle; A drive switching device actuator comprising: a control mechanism that controls driving of the motor based on an output from the switching request detection mechanism, wherein the control mechanism converts a voltage supplied from the battery into a predetermined drive voltage. Power supply circuit, a current detection circuit for detecting a current flowing through the motor, and an energization switching that is arranged between the power supply circuit and the motor and can be switched between energization and de-energization of the motor And an arithmetic processing unit that operates the energization switching circuit to drive the motor based on the current detected by the current detection circuit. The energization switching circuit includes a relay and a switching power element. The relay and the switching power element are energized only when both of the relay and the switching power element are on, and the motor is de-energized when at least one of the relay and the switching power element is off. A switching power element is provided, The current detection circuit, the relay, and the switching power element are connected in series, When the request for switching the driving state of the vehicle is not detected by the switching request detection mechanism, the arithmetic processing unit turns on one of the relay or the switching power element and turns off the other of the relay or the switching power element. Instruct A current flowing in a series circuit including the relay, the switching power element, and the motor, When the current detection circuit detects, The arithmetic processing unit includes: The actuator for the drive switching device is characterized in that it is determined that the other of the relay or the switching power element is out of order.
[0008]
The operation of the actuator for the drive switching device according to claim 1 will be described. When switching of the driving state is requested by the switching request detection mechanism, the energization switching circuit is operated by the arithmetic processing unit to energize the motor, and rotational torque is transmitted from the output shaft to the output member via the output mechanism. . At this time, the drive state may not be switched smoothly, and the output member may not operate or may operate while receiving an excessive load. In such a case, if energization of the motor is continued, the motor will generate excessive heat. However, in the present invention, the arithmetic processing unit turns on the relay and the power switching element based on the current detected by the current detection circuit.・ By turning off, the current flowing to the motor is limited. Therefore, heat generation of the motor can be suppressed without overcurrent flowing through the motor. To further explain the limitation of the energization current, the switching power element on / off operation cycle with respect to the relay is very small. Therefore, during the switching of the driving state, the switching power element is turned on / off while the relay remains on. By repeatedly switching off, the energization current to the motor is limited. When the switching of the driving state is completed, the energization switching circuit is operated so as to turn off both the relay and the switching power element.
[0009]
Here, the energization switching circuit has a configuration in which current does not flow to the motor when at least one of the relay and the switching power element is turned off unless the relay and the switching power element have failed. For the actuator having such a configuration, when it is detected that a current flows through the motor in a state where one of the relay or the switching power element is turned on and the other is turned off, the other of the relay or the switching power element is It can be regarded as a failure state (hereinafter referred to as “on failure”) that is not turned off while maintaining the on state.
[0010]
Thus, according to claim 1, the energization switching circuit for energization control of the motor at the time of switching the driving state uses the relay and the switching power element, and the relay and the switching power element are turned on / off. By operating, it is possible to detect an on-failure of the relay or the switching power element without providing a new monitoring circuit, and the number of parts does not increase when these failures are detected.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a cross-sectional view of a drive switching device 10 that employs an actuator for a drive switching device in the present embodiment. In FIG. 1, hatching is omitted except for some components so that each component is not easily seen.
[0012]
The drive switching device 10 is disposed between an input shaft 24 which is an output of a transmission (not shown), a front wheel drive shaft 12 and a rear wheel drive shaft 11 of the vehicle, and is an actuator for a drive switching device which will be described later. This is a device that switches the driving state of the vehicle to three states, that is, two-wheel drive, four-wheel drive (center differential lock), and four-wheel drive (center differential free) by operation. And a manual switch 50 as a switching request detection mechanism that detects whether or not there is a request to switch the driving state of the vehicle in accordance with an operation by the occupant. In addition to the three states, the drive switching device 10 according to the present embodiment is configured to be able to switch the final reduction ratio during four-wheel drive between a high gear and a low gear by the reducer 23. The high gear and the low gear are switched by manually switching the high & low shift lever 20 from the driver's seat. A rotational driving force is transmitted to the rear wheel drive shaft 11 via the input shaft 24, and the rotational driving force of the rear wheel drive shaft 11 can be transmitted from the center differential unit 13 to the front wheel drive shaft 12 via the silent chain 19. Has been. The center differential unit 13 is a device that absorbs the difference in rotational speed between the front wheel drive shaft 12 and the rear wheel drive shaft 11, and is constituted by a planetary gear mechanism.
[0013]
The configuration of the drive switching device 10 will be described. The drive switching device 10 includes a first shaft 14 that is coupled to a rod 33 that is an output member of the actuator unit 30 of the actuator for the drive switching device, a second shaft 15 that is disposed in parallel with the first shaft 14, A two-wheel drive / four-wheel drive shift fork 16 and a center differential lock shift fork 17 which are arranged so as to be axially movable within a predetermined range with respect to the first shaft 14 and the second shaft 15; Sleeves 16A and 17A fixed to the ends are provided. The first shaft 14 and the second shaft 15 are formed with a plurality of large-diameter portions 14A and 15A to define the axially movable range of the shift forks 16 and 17 with respect to the shafts 14 and 15, respectively. As the shaft 14 moves in the axial direction and the shift forks 16 and 17 are caught by the large diameter portions 14A and 15A, the respective axial positions of the shift forks 16 and 17 are defined.
[0014]
The switching of the drive state by the drive switching device 10 will be described. The drive switching device according to the present embodiment switches the driving state of the vehicle to three states of two-wheel drive, four-wheel drive (center differential lock), and four-wheel drive (center differential free) according to the position of the rod 33. When the first shaft 14 is moved in the axial direction in accordance with the position, the 2WD-4WD switching shift fork 16 and the center differential lock shift fork 17 disposed on the shafts 14 and 15 are moved in the axial direction. The sleeves 16A and 17A provided at the ends of the shift forks 16 and 17 are moved in the axial direction. As a result, the driving state of the vehicle is switched. In the four-wheel drive (center differential free) state, the member on the front wheel drive shaft 12 side and the center differential unit 13 are connected to absorb the difference in rotational speed between the drive shafts 11 and 12 by the planetary gear action of the planetary gear mechanism. However, the rotational driving force of the rear wheel drive shaft 11 is transmitted to the front wheel drive shaft 12 via the silent chain 19. In the four-wheel drive (center differential lock) state, the sleeve 17A is positioned on the upper side of the drawing, the planetary gear mechanism of the center differential unit 13 is locked, the front wheel drive shaft 12 and the rear wheel drive shaft 11 are directly connected, and both drive shafts 11 and 12 are rotationally driven at the same rotational speed. In the two-wheel drive state, the member on the front wheel drive shaft 12 side and the center differential unit 13 are not connected, and the rotational drive force of the input shaft 24 is transmitted only to the rear wheel drive shaft 11.
[0015]
Next, the actuator unit 30 constituting the drive switching device actuator will be described in detail. FIG. 2 is a cross-sectional view of the actuator unit 30 in the present embodiment, and FIG. 3 is a view as viewed in A of FIG. The actuator unit 30 includes a motor 31 that is driven to rotate in accordance with an energization current, an output mechanism 32 that converts the rotational torque of the output shaft 31A of the motor 31 into an axial thrust, and outputs the motor 31 via the output mechanism 32. Is transmitted between a rod 33 as an output member whose position is displaced according to the transmitted thrust, and between the output shaft 31A of the motor 31 and the output mechanism 32. Is disposed between the cycloid gear 34 and the output mechanism 32 as a reverse rotation prohibiting mechanism for prohibiting the rotation of the output shaft 31A by the power transmitted to the output shaft 31A side, and the rotation of the motor 31. And a rotation absorbing mechanism 35 that absorbs the rotation of the motor 31 when the rod 33 cannot reciprocate, and is disposed between the rotation absorbing mechanism 35 and the output shaft 31A. A limit switch 36 for detecting the rotational angle of the force shaft 31A is disposed in the housing 37. A worm gear may be used in place of the cycle load gear 34. Furthermore, the actuator for the drive switching device includes a control mechanism 40 outside the housing 37 that inputs a signal from the outside to select the driving state of the vehicle and outputs the energization to the motor 31 to achieve the selected driving state. Yes. A circuit configuration of the control mechanism 40 is shown in FIG.
[0016]
The rotation absorbing mechanism 35 includes a motor side rotating member 35A capable of transmitting the rotation of the output shaft 31A of the motor 31 via the cycloid gear 34, and one end of the rotation absorbing mechanism 35 fixed to the motor side rotating member 35A and the rotation direction of the motor side rotating member 35A. A spiral spring 35B as an elastic member that can be elastically compressed, an output-side rotating member 35C that is fixed to the other end of the spiral spring 35B and that can transmit a rotational force to the output mechanism 32, a motor-side rotating member 35A, and an output side And a plate 35D disposed between the rotating member 35C.
[0017]
The limit switch 36 has four terminals a, b, c, and d, and detects the rotation angle of the output shaft 31A by changing the combination of contact and non-contact of each terminal according to the rotation angle of the output shaft 31A. Thus, the position of the rod 33 corresponding to the three driving states and the intermediate position of each position can be detected. Table 1 is a table showing the relationship between the contact state of each terminal a, b, c, d of the limit switch 36 and the set position of the driving state of the vehicle. In Table 1, ◯ indicates when the contact is in contact, and the blank indicates when there is no contact.
[0018]
[Table 1]

As shown in Table 1, when the contact state of the four terminals a, b, c, and d changes, the setting positions I to V of the limit switch 36 are detected, and further, the setting position is any of I to V. Thus, the setting positions A to C of the driving state of the vehicle and their intermediate positions are detected. Here, the set position A indicates the two-wheel drive, the set position B indicates the four-wheel drive (center differential free), and the set position C indicates the axial position of the rod 33 corresponding to the four-wheel drive (center differential lock). The terminal a of the limit switch 36 is ground and is always in contact.
[0019]
The control mechanism 40 which comprises the actuator for drive switching devices with the actuator part 30 is demonstrated. The control mechanism 40 includes a power supply circuit 48 that converts a voltage supplied from the battery BAT into a predetermined drive voltage, a current detection circuit 45 that detects a current flowing through the motor 31, and a power supply circuit 48 and a motor 31. An energization switching circuit 42 that can be switched between energization / non-energization of the motor 31 and a CPU 41 as an arithmetic processing unit that operates the energization switching circuit 42 to drive the motor 31 based on the current detected by the current detection circuit 45. It has.
[0020]
The energization switching circuit 42 includes relays 43A and 43B and a switching power element FET 44. The motor 31 is energized only when both the relay 43A and the FET 44 are on or both the relay 43B and the FET 44 are on. The relays 43A, 43B and the FET 44 are arranged so that the motor 31 is de-energized when at least one of the relay 43A and the FET 44 is off, or when at least one of the relay 43B and the FET 44 is off. In the present embodiment, the energization switching circuit 42 has two relays 43A and 43B, which are a relay 43A that is turned on when the motor 31 is rotated in the forward rotation direction, and the motor 31 in the reverse rotation direction. The relay 43B is turned on when rotating, and the two relays 43A and 43B are not turned on at the same time when the driving state is switched. Further, the FET 44 is provided between the motor 31 and the ground, so that one FET has a structure corresponding to the two relays 43A and 43B. In addition to the configuration shown in FIG. 4, two FETs may be arranged so that each of the FETs corresponds to the relay 43 </ b> A and the relay 43 </ b> B.
[0021]
The current detection circuit 45 compares the current flowing through the resistor 47 with the reference current value I0, the first predetermined current value I1, and the second predetermined current value I2 by the operational amplifier 46, so that the current flowing through the motor 31 becomes these current values. Whether or not it has been reached is detected. The reference current value I0 is the smallest value among the currents that can be detected by the CPU 41.
[0022]
The CPU 41 inputs the power supply circuit 48, vehicle speed, on / off of the manual switch 50, contact / non-contact of the terminals b, c, d of the limit switch 36, and the current detected by the current detection circuit. The rotation direction of the motor 31 and the energization current are calculated so that the driving state is in accordance with the received signal, and the relays 43A and 43B and the FET 44 are turned on / off to output the calculated rotation direction and current value. Regarding the current flowing through the motor 31, the current flowing through the resistor 47 is compared with each current value by the operational amplifier 46, so that the current flowing through the motor 31 is the reference current value I 0, the first predetermined current value I 1, or the second predetermined current. It is detected whether or not the value I2 has been reached.
[0023]
Detection of a failure of the actuator for the drive switching device will be described with reference to the flowchart of FIG. When a voltage is supplied from the power supply circuit 48 to the CPU 41 and the ignition switch IG is turned on, the flowchart of FIG. 5 starts. First, in step S10, the relay 43A is turned on and the relay 43B is turned off. In step S11, the FET 44 is turned off. Next, it progresses to step S12 and it is judged whether the electric current I which flows into the motor 31 is larger than the reference electric current value I0. If the FET 44 is turned off as instructed by the CPU 41, no current flows through the motor 31. Therefore, the current I does not become larger than the reference current value I0 unless the FET 44 is turned on. If the FET 44 is not on-failed and it is determined in step S12 that the current I is less than or equal to the reference current value I0, the process proceeds to step S13, where the relay 43A is turned off and the relay 43B is turned on. Then, in step S14, it is determined whether or not the current I is larger than the reference current value I0 as in step S12. Since the FET 44 is turned off when the step S14 is executed, the current I does not become larger than the reference current value I0 unless the FET 44 is turned on. If the FET 44 is not on-failed and it is determined in step S14 that the current I is less than or equal to the reference current value I0, the process proceeds to step S15.
[0024]
In step S16, both the relays 43A and 43B are turned off, and the FET 44 is turned on in step S17. And it progresses to step S17 and it is judged whether the electric current I is larger than the reference electric current value I0 similarly to step S12 and step S14. Since both of the relays 43A and 43B are turned off at the time of execution of step S17, current does not flow through the motor 31 unless either the relay 43A or the relay 43B has an on failure. If neither of the relays 43A and 43B is on-failed and it is determined in step S17 that the current I is less than or equal to the reference current value I0, the process proceeds to step S19 and normal energization control described later is executed.
[0025]
Here, if the FET 44 is on-failed, a current flows through the motor 31, and it is determined in step S12 that the current I is greater than the reference current value I0, and the process proceeds to step S18. If the FET 44 is on-failed, a current flows through the motor 31, and it is determined in step S14 that the current I is greater than the reference current value I0, and the process proceeds to step S18. Even when either of the relays 43A and 43B is on-failed, current flows through the motor 31 and it is determined in step S17 that the current I is larger than the reference current value I0. Proceed to step S18. In step S18, the relays 43A and 43B and the FET 44 are turned off so that the motor 31 is not energized even if the driver requests to switch the driving state. Then, an indicator (not shown) is turned on to inform the driver that the relays 43A, 43B or the FET 44 is on.
[0026]
Next, the normal energization control in step S19 will be described using the flowchart of FIG. 6 and the time charts of FIGS. In the present embodiment, the operation of each component when the driving state of the vehicle is switched from four-wheel drive (center differential free) to four-wheel drive (center differential lock) will be described. 7 and 9 show the relationship between the current flowing through the motor 31 and time, and FIGS. 8 and 10 show the relationship between the stroke of the rod 33 and time.
[0027]
When the control is started, first, the process proceeds to step S100, and it is determined whether the manual switch 50 is turned on in order to determine whether the drive switching device 10 has requested switching. If it is determined that the manual switch 50 has been turned on, it is determined that there is a switching request, it is determined Yes, the process proceeds to step S110, and the CPU 41 outputs ON / OFF signals of the relays 43A, 43B and the FET 44 to the motor 31. Energization is started (t0).
[0028]
Then, the process proceeds to step S120, and it is determined whether or not the control (inrush control) for intentionally suppressing the inrush current flowing in the motor 31 by the start of energization of the motor 31 is completed. In step S120, it is actually determined whether or not a predetermined time (t1) has elapsed since the start of energization of the motor 31 in step S110. Step S120 is repeatedly processed until time (t1) elapses.
[0029]
If it determines with Yes at step S120, it will progress to step S130 and the control which always energizes the motor 31 will be performed. When the constant energization of step S130 is started, a stable current I2 flows to the motor 31, the output shaft 31A is rotationally driven, and the rod 33 is displaced in the axial direction via the output mechanism 32. From time t0 to t2, the displacement of the rod 33 in the axial direction is not restricted, and the rod 33 strokes in proportion to the time. Note that the load acting on the spiral spring 35B between the times t0 and t2 is only the sliding resistance of each member.
[0030]
Next, in step S140, based on the set position of the limit switch 36 shown in Table 1, it is determined whether or not the movement of the rod 33 is completed (whether the rod 33 has moved to a desired position). Here, when the center differential lock shift fork 17 is displaced in the axial direction along with the stroke of the rod 33, the spline formed on the inner and outer periphery of the sleeve 17A and the spline formed on the center differential unit 13 mesh with each other. The sleeve 17A integrally rotates the planetary gear mechanism so that the planetary gear mechanism does not act, and the center differential lock state is established, and the movement of the rod 33 is completed. However, even if the sleeve 17A is displaced in the axial direction, the planetary gear mechanism operates in the center differential-free state, so the splines formed on the inner and outer circumferences of the sleeve 17A and the splines formed on the center differential unit 13 are different. The spiral spring 35B is kept in an elastic state (hereinafter referred to as a waiting state) until the spline of the sleeve 17A and the spline of the center differential unit 13 are engaged and the movement of the rod 33 is completed. is doing. This waiting state includes two states, a state in which the rod 33 cannot be displaced in the axial direction (first state) and a state in which the rod 33 is displaced in the axial direction while receiving a predetermined load (second state). Under this condition, the value of the current flowing through the motor 31 gradually increases.
[0031]
When the movement of the rod 33 is not completed, it is determined No in step S140, and the process proceeds to step S150. In step S150, it is determined whether or not the current flowing through the motor 31 is equal to or greater than a second predetermined current value I2. Under the first state or the second state described above, since the splines are not normally meshed, a load is applied to the motor 31, and the current flowing through the motor 31 is equal to or greater than the second predetermined current value I2. The second predetermined current value I2 is set to a current value that is slightly larger than the current value Is that flows through the motor 31 when the rod 33 moves without receiving an excessive load in a state where the splines are normally engaged. The current value Is is a value equivalent to the value of the current flowing through the motor 31 in the range of time t1 to t2.
[0032]
If the current flowing through the motor 31 is greater than or equal to the second predetermined current value I2, it is determined Yes in step S150, and the process proceeds to step S160. In step S160, it is determined whether or not the current flowing through the motor 31 is smaller than a first predetermined current value I1 (I1> I2). Note that the first predetermined current value I1 is the first state in which the rod 33 is locked and the rod 33 cannot be operated because the spline is not engaged even though the motor 31 is energized. It is set to have a current value flowing through the motor 31. That is, the first predetermined current value I1 is a current value that is estimated to flow through the motor 31 when energization of the motor 31 is not restricted (during constant energization) while the output shaft 31A of the motor 31 cannot rotate. is there.
[0033]
If the current of the motor 31 is greater than or equal to the first predetermined current value I1 in step S160 (time t3 in FIG. 6), No is determined in step S160 and the process proceeds to step S180. In this case, it is determined as the first state in which the rod 33 is locked and the rod 33 cannot be operated without being engaged with the spline (time t2 to t5 in FIG. 7).
[0034]
In step S180, the energization current of the motor 31 is limited to suppress the heat generation of the motor 31. In step S180, the current flowing through the motor 31 by PWM control is set to a third predetermined current I3 (I1>I3> I2), and current is turned on / off by ON / OFF control. Specifically, once step S180 is executed, the current of the motor 31 is set to the third predetermined current value I3 by PWM control, and the counter is incremented by one. If step S180 is performed, it will return to step S140 and it will be determined whether the movement of the rod 33 was completed again. The process of step S180 is repeatedly executed unless the movement of the rod 33 is completed, and the energization current to the motor continues to maintain the third predetermined current value I3 until the value of the counter becomes N1. When the value of the counter becomes N1, the counter is cleared and the energization current is switched from ON control to OFF control. Thereafter, when step S180 is executed, energization to the motor 31 is stopped and the counter is incremented by one. Unless the movement of the rod 33 is completed or the value of the current flowing through the motor 31 does not change, step S180 is repeatedly executed, and the motor is not energized until the counter value reaches N2. When the counter value reaches N2, the counter is cleared and the current is switched from OFF control to ON control again. As described above, when step S180 is repeatedly performed (N1 + N2 or more) without completing the movement of the rod 33, PWM control and ON / OFF control of the energization current to the motor 31 are performed, and the motor 31 due to overcurrent is performed. Reduces heat generation. Here, the PWM control and the ON / OFF control represented by the time t3 to t5 in FIG. Since the output shaft 31A is connected to the rotation absorption mechanism 35 via the cycloid gear 34, the output shaft 31A does not rotate in the reverse direction even when the motor 31 is de-energized (during OFF control). ON / OFF control of energization / non-energization of current becomes possible.
[0035]
If the current of the motor 31 is smaller than the first predetermined current value I1 in step S160 (time t3 in FIG. 8), Yes is determined in step S160 and the process proceeds to step S170. When it is determined Yes in step S160, the current flowing through the motor 31 is between the second predetermined current value I2 and the first predetermined current value I1. In this case, it is determined that the rod 33 is operating, but the output shaft 31A of the motor 31 is in a second state in which a load is applied (time t3 to t4 in FIG. 9). In the second state, for example, the spline is not completely engaged but the spline is engaged slowly by the thrust of the rod 33 obtained by driving the motor 31, or the planetary gear mechanism is operated by the operation of the planetary gear mechanism. A case where the load at the time of sliding contact between the side surface of the spline and the side surface of the spline of the rod 33 is large can be considered. In step S170, it is determined whether or not the time after determining Yes in step S150 is equal to or longer than a predetermined time ts. That is, it is determined whether or not the time after the motor 31 has entered the second state has passed the predetermined time ts. The predetermined time ts in step S170 is set in advance so that the heat generation amount of the motor 31 when the second state of the motor 31 is continued is in a range not exceeding the allowable heat generation amount of the motor 31. It is set according to the value of the flowing current. If the motor 31 is in the second state but does not exceed the predetermined time ts, it is determined No in step S170, the process returns to step S130, and the motor 31 is always energized. When the second state continues for a predetermined time ts or longer (time t4 in FIG. 8), it is determined Yes in step S170, and the process proceeds to step S190.
[0036]
In step S190, the energization current of the motor 31 is limited in order to suppress the heat generation of the motor 31. In step S190, the current flowing through the motor 31 by the PWM control is set to the second predetermined current I2, and the current is turned on and off by the ON / OFF control. Specifically, once step S190 is executed, the second predetermined current value I2 is maintained by PWM control, and the counter is incremented by one. If step S190 is performed, it will return to step S140 and will determine again whether the movement of the rod 33 was completed. The process in step S190 is repeated unless the movement of the rod 33 is completed, and the energization current to the motor continues to maintain the second predetermined current value I2 until the value of the counter becomes N3. When the value of the counter reaches N3, the counter is cleared and the energized current is switched from ON control to OFF control. Thereafter, when step S190 is executed, energization of the motor 31 is stopped and the counter is incremented by one. Unless the movement of the rod 33 is completed or the value of the current flowing through the motor 31 does not change, step S190 is repeatedly executed, and the motor is not energized until the counter value becomes N4. When the value of the counter becomes N4, the counter is cleared and the current is switched from OFF control to ON control again. As described above, when step S190 is repeatedly executed (N3 + N4 or more) without completing the movement of the rod 33, PWM control and ON / OFF control of the energization current to the motor 31 are performed, and the motor 31 due to overcurrent is performed. Reduces heat generation. Here, the PWM control and the ON / OFF control represented by the time t4 to t5 in FIG.
[0037]
After the intermittent energization control 1 is performed from the first state, the spline of the sleeve 17A and the spline of the center differential unit 13 mesh with each other so that the rod 33 approaches a desired position, or after the intermittent energization control 2 is performed from the second state. When the rod 33 gradually moves and approaches the desired position, the spiral spring 35B shifts from the elastic state to the non-elastic state, so the load on the spiral spring 35B becomes small. Therefore, the load applied to the output shaft 31A of the motor 31 becomes small, and the current flowing through the motor 31 becomes smaller than the third predetermined current value I3 or the second predetermined current value I2 (time t5 in FIGS. 6 and 8). And the control which always energizes the motor 31 is performed (time t6). When energization is always started in this state, a stable current Is flows to the motor 31 and the output shaft 31A is rotationally driven, and the sleeve 17A is displaced along the spline to the position where the switching of the driving state is completed (from time t6 to t7). ). When the movement of the rod 33 is completed, the limit switch 36 is switched to a desired position. Therefore, in step S140, it is determined that the movement of the rod 33 is completely completed, and the process proceeds to step S220 to stop energizing the motor 31. At the same time, this control is temporarily terminated. As described above, the above-described steps are executed to complete the switching of the drive switching device from the four-wheel drive (center differential free) to the four-wheel drive (center differential lock) while suppressing the heat generation of the motor 31.
[0038]
In the above-described embodiment, the normal energization control is executed after detecting the ON failure of the FET and the relay, but the present invention is not limited to the above-described embodiment, and other than this, It is conceivable to detect an on-failure. In general, the time required for the switching element to be turned on / off is much shorter than the time required for the relay to be turned on / off. Therefore, for example, a relay failure can be detected by turning on the switching element while the relay is turned off after the switch is requested during normal energization control until the relay is turned on. . Specifically, this is achieved by executing the processing of steps S15 to S17 between step S110 and step S120. This is preferable because it is possible to detect an ON failure of the relay every time there is a switching request without impairing the responsiveness of the actuator for the drive switching device.
[0039]
Further, for example, when detecting an on failure of the FET, the relays 43A and 2 are simultaneously turned on and the FET is turned off. If a current is flowing through the motor 31, it is determined that one of the FETs is on. It may be. Specifically, this is achieved by simultaneously turning on the relays 43A and 2 in step S10 and omitting steps S13 and S14. According to this, the processing required for detecting the ON failure of the FET is reduced, which is preferable.
[0040]
【The invention's effect】
According to the present invention, by operating on / off of a relay and FET that are used for energization control of a motor at the time of switching of a driving state, an ON failure of the relay or FET is detected without newly providing a monitoring circuit. The number of parts does not increase when detecting these failures.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a drive switching device according to an embodiment of the present invention.
FIG. 2 is a sectional view of a drive switching actuator in the present embodiment.
FIG. 3 is a view on A in FIG. 2;
FIG. 4 is a circuit diagram of a control mechanism in the present embodiment.
FIG. 5 is a flowchart showing failure detection processing by the control mechanism in the present embodiment.
FIG. 6 is a flowchart showing normal energization control by the control mechanism in the present embodiment.
FIG. 7 is a time chart according to the drive switching actuator in the present embodiment.
FIG. 8 is a time chart according to the drive switching actuator in the present embodiment.
FIG. 9 is a time chart according to the drive switching actuator in the present embodiment.
FIG. 10 is a time chart according to the drive switching actuator in the present embodiment.
[Explanation of symbols]
10 ... Drive switching device
30 ... Actuator
31 ... Motor
32 ... Output mechanism
33 ... Rod (output member)
34 ... Cycloid gear (reverse rotation prohibition mechanism)
35 ... Rotation absorption mechanism
36 ... Limit switch
40 ... Control mechanism
41 ... CPU (arithmetic processing unit)
42 .. energization switching circuit
43A, 43B ... Relay
44 ... FET (FET)
45 ... Current detection circuit
48 ... Power supply circuit
50 ... Manual switch (switching request detection mechanism)
BAT ... Battery

Claims (6)

A motor that rotates according to the energization current, an output mechanism that outputs the rotational torque of the output shaft of the motor, a thrust according to the rotational torque of the motor is transmitted through the output mechanism, and the position displacement An output member capable of switching the driving state of the vehicle in response to the output, a switching request detecting mechanism for detecting whether or not there is a request for switching the driving state of the vehicle, and driving of the motor based on an output from the switching request detecting mechanism An actuator for a drive switching device comprising: a power supply circuit that converts a voltage supplied from a battery into a predetermined drive voltage; and a current that detects a current flowing through the motor. A detection circuit, an energization switching circuit disposed between the power supply circuit and the motor and capable of switching energization / non-energization of the motor, and a current detected by the current detection circuit. And an arithmetic processing unit that operates the energization switching circuit to drive the motor. The energization switching circuit includes a relay and a switching power element, and both the relay and the switching power element are turned on. The relay and the switching power element are disposed so that the motor is energized only when at least one of the relay and the switching power element is off, and the motor is de-energized when the current is The detection circuit, the relay, and the switching power element are connected in series, and when the request for switching the driving state of the vehicle is not detected by the switching request detection mechanism, the arithmetic processing unit detects the relay or the switching power. One of the elements is turned on and the other of the relay or the switching power element There was instructed to turn off, and the relay, and the switching power element, a current flowing through the series circuit including said motor, when the current detection circuit detects, the arithmetic processing unit, the relay Or it is judged that the other of the said switching power elements has failed, The actuator for drive switching devices characterized by the above-mentioned.  If the arithmetic processing unit determines that the relay or the switching power element is out of order, even if a request for switching the driving state of the vehicle by the switching request detection mechanism is detected, the motor is sent to the motor. The drive switching device actuator according to claim 1, wherein no energization is performed. The arithmetic processing unit instructs the relay to be turned on and the switching power element to be turned off when the request for switching the driving state of the vehicle is not detected by the switching request detection mechanism, and the current detection circuit Is detected, and when the switching request detection mechanism detects a request to switch the driving state of the vehicle, the relay is turned off and the switching power is detected. The operation processing device determines that the relay is out of order when an element is instructed to be turned on and the current detection circuit detects a current. Item 3. The drive switching device actuator according to Item 2. The relay includes one relay that is turned on when the motor is rotated in the forward rotation direction, and another relay that is turned on when the motor is rotated in the reverse rotation direction. When a request to switch the driving state of the vehicle is not detected by the detection mechanism, an instruction is given to turn on one of the one relay or the other relay, turn off the other, and turn off the switching power element. In this state, when the current detection device detects a current flowing through the series circuit, the arithmetic processing unit determines that the switching power element is faulty. The actuator for drive switching apparatuses as described in any one of thru | or 3. The relay includes one relay that is turned on when the motor is rotated in the forward rotation direction, and another relay that is turned on when the motor is rotated in the reverse rotation direction. When a request to switch the driving state of the vehicle is not detected by the detection mechanism, both the one relay and the other relay are instructed to turn off, and the switching power element is instructed to turn on. The said processing unit judges that the said switching power element has failed when the said current detection apparatus detects the electric current which the said current detection apparatus flows into the said series circuit, The 1st thru | or characterized by the above-mentioned. The actuator for a drive switching device according to any one of claims 4 to 4. The relay includes one relay that is turned on when the motor is rotated in the forward rotation direction, and another relay that is turned on when the motor is rotated in the reverse rotation direction. When a request to switch the driving state of the vehicle is not detected by the detection mechanism, the one relay and the other relay are turned on and the switching power element is instructed to be turned off. In this state, the current detection 4. The apparatus according to claim 1, wherein when the apparatus detects a current flowing through the series circuit, the arithmetic processing unit determines that the switching power element is out of order. 5. Actuator for drive switching device.

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