JP2005003094A - Automobile engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automobile engine with a piston ring and a piston skirt having improved scuffing and wear resistance and greatly reduced friction. <P>SOLUTION: The automobile engine comprises a cylinder block bore portion 2a formed of an eutectic or hypereutectic aluminum alloy, and the piston ring 4 and the piston skirt 3a to be slid relative to the cylinder block bore portion 2a under the existence of lubricating oil. Each of portions of the piston ring 4 and the piston skirt 3a to be slid relative to the cylinder block bore portion 2a is covered with a hard carbon thin film 5. The amount of hydrogen atoms contained in the hard carbon thin film 5 is 1 atom% or less. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００３２】
【化２】

【００３３】
これら一般式におけるＰＩＢは、ポリブテニル基を示し、高純度イソブテン又は１−ブテンとイソブテンの混合物をフッ化ホウ素系触媒又は塩化アルミニウム系触媒で重合させて得られる数平均分子量が９００〜３５００、望ましくは１０００〜２０００のポリブテンから得られる。上記数平均分子量が９００未満の場合は清浄性効果が劣り易く、３５００を超える場合は低温流動性に劣り易いため、望ましくない。
【００３４】
また、上記一般式におけるｎは、清浄性に優れる点から１〜５の整数、より望ましくは２〜４の整数であることがよい。更に、上記ポリブテンは、製造過程の触媒に起因して残留する微量のフッ素分や塩素分を吸着法や十分な水洗等の適切な方法により、５０ｐｐｍ以下、より望ましくは１０ｐｐｍ以下、特に望ましくは１ｐｐｍ以下まで除去してから用いることもよい。
【００３５】
更に、上記ポリブテニルコハク酸イミドの製造方法としては、特に限定はないが、例えば、上記ポリブテンの塩素化物又は塩素やフッ素が充分除去されたポリブテンと無水マレイン酸とを１００〜２００℃で反応させて得られるポリブテニルコハク酸を、ジエチレントリアミン、トリエチレンテトラミン、テトラエチレンペンタミン、ペンタエチレンヘキサミン等のポリアミンと反応させることにより得ることができる。
【００３６】
一方、上記ポリブテニルコハク酸イミドの誘導体としては、上記一般式（１）又は（２）で表される化合物に、ホウ素化合物や含酸素有機化合物を作用させて、残存するアミノ基及び／又はイミノ基の一部又は全部を中和したり、アミド化した、いわゆるホウ素変性又は酸変性化合物を例示できる。その中でもホウ素含有ポリブテニルコハク酸イミド、特にホウ素含有ビスポリブテニルコハク酸イミドが最も好ましいものとして挙げられる。
【００３７】
上記ホウ素化合物としては、ホウ酸、ホウ酸塩、ホウ酸エステル等が挙げられる。具体的には、上記ホウ酸として、オルトホウ酸、メタホウ酸及びテトラホウ酸などが挙げられる。また、上記ホウ酸塩としては、アンモニウム塩等、具体的には、例えばメタホウ酸アンモニウム、四ホウ酸アンモニウム、五ホウ酸アンモニウム、八ホウ酸アンモニウム等のホウ酸アンモニウムが好適例として挙げられる。また、ホウ酸エステルとしては、ホウ酸と好ましくは炭素数１〜６のアルキルアルコールとのエステル、より具体的には例えば、ホウ酸モノメチル、ホウ酸ジメチル、ホウ酸トリメチル、ホウ酸モノエチル、ホウ酸ジエチル、ホウ酸トリエチル、ホウ酸モノプロピル、ホウ酸ジプロピル、ホウ酸トリププロピル、ホウ酸モノブチル、ホウ酸ジブチル、ホウ酸トリブチル等が好適例として挙げられる。なお、ホウ素含有ポリブテニルコハク酸イミドにおけるホウ素含有量Ｂと窒素含有量Ｎとの質量比「Ｂ／Ｎ」は、通常０．１〜３であり、好ましくは、０．２〜１である。
【００３８】
また、上記含酸素有機化合物としては、具体的には、例えばぎ酸、酢酸、グリコール酸、プロピオン酸、乳酸、酪酸、吉草酸、カプロン酸、エナント酸、カプリル酸、ペラルゴン酸、カプリン酸、ウンデシル酸、ラウリン酸、トリデカン酸、ミリスチン酸、ペンタデカン酸、パルミチン酸、マルガリン酸、ステアリン酸、オレイン酸、ノナデカン酸、エイコサン酸等の炭素数１〜３０のモノカルボン酸や、シュウ酸、フタル酸、トリメリット酸、ピロメリット酸等の炭素数２〜３０のポリカルポン酸並びにこれらの無水物、又はエステル化合物、炭素数２〜６のアルキレンオキサイド、ヒドロキシ（ポリ）オキシアルキレンカーボネート等が挙げられる
【００３９】
なお、本発明に用いる潤滑油組成物において、ポリブテニルコハク酸イミド及び／又はその誘導体の含有量は、０．１〜１５％が望ましく、より望ましくは１．０〜１２％であることが好ましい。０．１％未満では清浄性効果に乏しくなることがあり、１５％を超えると含有量に見合う清浄性効果が得られにくく、抗乳化性が悪化し易い。
【００４０】
更にまた、本発明に用いる潤滑油組成物は、次の一般式（３）で表されるジチオリン酸亜鉛を含有することが好適である。
【００４１】
【化３】

【００４２】
上記式（３）中のＲ^４、Ｒ^５、Ｒ^６及びＲ^７は、それぞれ別個に炭素数１〜２４の炭化水素基を示す。これら炭化水素基としては、炭素数１〜２４の直鎖状又は分枝状のアルキル基、炭素数３〜２４の直鎖状又は分枝状のアルケニル基、炭素数５〜１３のシクロアルキル基又は直鎖状若しくは分枝状のアルキルシクロアルキル基、炭素数６〜１８のアリール基又は直鎖状若しくは分枝状のアルキルアリール基、炭素数７〜１９のアリールアルキル基等のいずれかであることが望ましい。また、アルキル基やアルケニル基は、第１級、第２級及び第３級のいずれであってもよい。
【００４３】
上記Ｒ^４、Ｒ^５、Ｒ^６及びＲ^７としては、具体的には、メチル基、エチル基、プロピル基、ブチル基、ペンチル基、へキシル基、ヘプチル基、オクチル基、ノニル基、デシル基、ウンデシル基、ドデシル基、トリデシル基、テトラデシル基、ペンタデシル基、ヘキサデシル基、ヘプタデシル基、オクタデシル基、ノナデシル基、イコシル基、ヘンイコシル基、ドコシル基、トリコシル基、テトラコシル基等のアルキル基、プロペニル基、イソプロペニル基、ブテニル基、ブタジエニル基、ペンテニル基、ヘキセニル基、ヘプテニル基、オクテニル基、ノネニル基、デセニル基、ウンデセニル基、ドデセニル基、トリデセニル基、テトラデセニル基、ペンタデセニル基、ヘキサデセニル基、ヘプタデセニル基、オレイル基等のオクタデセニル基、ノナデセニル基、イコセニル基、ヘンイコセニル基、ドコセニル基、トリコセニル基、テトラコセニル基等のアルケニル基、シクロペンチル基、シクロへキシル基、シクロヘプチル基等のシクロアルキル基、メチルシクロペンチル基、ジメチルシクロペンチル基、エチルシクロペンチル基、プロピルシクロペンチル基、エチルメチルシクロペンチル基、トリメチルシクロペンチル基、ジエチルシクロペンチル基、エチルジメチルシクロペンチル基、プロピルメチルシクロペンチル基、プロピルエチルシクロペンチル基、ジ−プロピルシクロペンチル基、プロピルエチルメチルシクロペンチル基、メチルシクロへキシル基、ジメチルシクロへキシル基、エチルシクロへキシル基、プロピルシクロへキシル基、エチルメチルシクロへキシル基、トリメチルシクロへキシル基、ジエチルシクロヘキシル基、エチルジメチルシクロヘキシル基、プロピルメチルシクロヘキシル基、プロピルエチルシクロヘキシル基、ジ−プロピルシクロへキシル基、プロピルエチルメチルシクロヘキシル基、メチルシクロヘプチル基、ジメチルシクロヘプチル基、エチルシクロヘプチル基、プロピルシクロヘプチル基、エチルメチルシクロヘプチル基、トリメチルシクロヘプチル基、ジエチルシクロヘプチル基、エチルジメチルシクロヘプチル基、プロピルメチルシクロヘプチル基、プロピルエチルシクロヘプチル基、ジ−プロピルシクロヘプチル基、プロピルエチルメチルシクロヘプチル基等のアルキルシクロアルキル基、フェニル基、ナフチル基等のアリール基、トリル基、キシリル基、エチルフェニル基、プロピルフェニル基、エチルメチルフェニル基、トリメチルフェニル基、ブチルフェニル基、プロピルメチルフェニル基、ジエチルフェニル基、エチルジメチルフェニル基、テトラメチルフェニル基、ペンチルフェニル基、ヘキシルフェニル基、ヘプチルフェニル基、オクチルフェニル基、ノニルフェニル基、デシルフェニル基、ウンデシルフェニル基、ドデシルフェニル基等のアルキルアリール基、ベンジル基、メチルベンジル基、ジメチルベンジル基、フェネチル基、メチルフェネチル基、ジメチルフェネチル基等のアリールアルキル基、等が例示できる。
【００４４】
なお、Ｒ^４、Ｒ^５、Ｒ^６及びＲ^７がとり得る上記炭化水素基には、考えられる全ての直鎖状構造及び分枝状構造をが含まれ、また、アルケニル基の二重結合の位置、アルキル基のシクロアルキル基への結合位置、アルキル基のアリール基への結合位置、及びアリール基のアルキル基への結合位置は任意である。また、上記炭化水素基の中でも、その炭化水素基が、直鎖状又は分柱状の炭素数１〜１８のアルキル基である場合若しくは炭素数６〜１８のアリール基、又は直鎖状若しくは分枝状アルキルアリール基である場合が特に好ましい。
【００４５】
上記ジチオリン酸亜鉛の好適な具体例としては、例えば、ジイソプロピルジチオリン酸亜鉛、ジイソブチルジチオリン酸亜鉛、ジ−ｓｅｃ−ブチルジチオリン酸亜鉛、ジ−ｓｅｃ−ペンチルジチオリン酸亜鉛、ジ−ｎ−ヘキシルジチオリン酸亜鉛、ジ−ｓｅｃ−ヘキシルジチオリン酸亜鉛、ジ−オクチルジチオリン酸亜鉛、ジ−２−エチルヘキシルジチオリン酸亜鉛、ジ−ｎ−デシルジチオリン酸亜鉛、ジ−ｎ−ドデシルジチオリン酸亜鉛、ジイソトリデシルジチオリン酸亜鉛、及びこれらの任意の組合せに係る混合物等が挙げられる。
【００４６】
また、上記ジチオリン酸亜鉛の含有量は、より高い摩擦低減効果を発揮させる観点から、組成物全量基準且つリン元素換算量で、０．１％以下であることが好ましく、また０．０６％以下であることがより好ましく、更にはジチオリン酸亜鉛が含有されないことが特に好ましい。ジチオリン酸亜鉛の含有量がリン元素換算量で０．１％を超えると、ＤＬＣ部材と鉄基部材との摺動面における上記脂肪酸エステル系無灰摩擦調整剤や上記脂肪族アミン系無灰摩擦調整剤の優れた摩擦低減効果が阻害されるおそれがある。
【００４７】
上記ジチオリン酸亜鉛の製造方法としては、従来方法を任意に採用することができ、特に制限されないが、具体的には、例えば、上記Ｒ^４、Ｒ^５、Ｒ^６及びＲ^７に対応する炭化水素基を持つアルコール又はフェノールを五二硫化りんと反応させてジチオリン酸とし、これを酸化亜鉛で中和させることにより合成することができる。なお、上記ジチオリン酸亜鉛の構造は、使用する原料アルコールによって異なることは言うまでもない。
【００４８】
本発明においては、上記一般式（３）に包含される２種以上のジチオリン酸亜鉛を任意の割合で混合して使用することもできる。
【００４９】
上述のように、本発明の自動車用エンジンにおいて、潤滑油組成物は、硬質炭素薄膜で被覆した摺動相手部材のシリンダブロックボア部との摺動部分に用いた場合に、極めて優れた低摩擦特性を示すものであるが、特に内燃機関用潤滑油組成物として必要な性能を高める目的で、金属系清浄剤、酸化防止剤、粘度指数向上剤、他の無灰摩擦調整剤、他の無灰分散剤、磨耗防止剤若しくは極圧剤、防錆剤、非イオン系界面活性剤、抗乳化剤、金属不活性化剤、消泡剤等を単独で又は複数種を組合せて配合し、必要な性能を高めることができる。
【００５０】
上記金属系清浄剤としては、潤滑油用の金属系清浄剤として通常用いられる任意の化合物が使用できる。例えば、アルカリ金属又はアルカリ土類金属のスルホネート、フェネート、サリシレートナフテネート等を単独で又は複数種を組合せて使用できる。ここで、上記アルカリ金属としてはナトリウム（Ｎａ）やカリウム（Ｋ）等、上記アルカリ土類金属としてはカルシウム（Ｃａ）やマグネシウム（Ｍｇ）等が例示できる。また、具体的な好適例としては、Ｃａ又はＭｇのスルフォネート、フェネート及びサリシレートが挙げられる。
【００５１】
なお、これら金属系清浄剤の全塩基価及び添加量は、要求される潤滑油の性能に応じて任意に選択できる。通常、全塩基価は、過塩素酸法で０〜５００ｍｇＫＯＨ／ｇ、望ましくは１５０〜４００ｍｇＫＯＨ／ｇであり、その添加量は組成物全量基準で、通常０．１〜１０％である。
【００５２】
また、上記酸化防止剤としては、潤滑油用の酸化防止剤として通常用いられる任意の化合物を使用できる。例えば、４，４’−メチレンビス（２，６−ジ−ｔｅｒｔ−ブチルフェノール）、オクタデシル−３−（３，５−ジ−ｔｅｒｔ−ブチル−４−ヒドロキシフェニル）プロピオネート等のフェノール系酸化防止剤、フェニル−α−ナフチルアミン、アルキルフェニル−α−ナフチルアミン、アルキルジフェニルアミン等のアミン系酸化防止剤、並びにこれらの任意の組合せに係る混合物等が挙げられる。また、かかる酸化防止剤の添加量は、組成物全量基準で、通常０．０１〜５％である。
【００５３】
更に、上記粘度指数向上剤としては、具体的には、各種メタクリル酸エステルから選ばれる１種又は２種以上のモノマーの共重合体やその水添物等のいわゆる非分散型粘度指数向上剤、及び更に窒素化合物を含む各種メタクリル酸エステルを共重合させたいわゆる分散型粘度指数向上剤等が例示できる。また、他の粘度指数向上剤の具体例としては、非分散型又は分散型エチレン−α−オレフィン共重合体（α−オレフィンとしては、例えばプロピレン、１−ブテン、１−ペンテン等）及びその水素化物、ポリイソブチレン及びその水添物、スチレン−ジエン水素化共重合体、スチレン−無水マレイン酸エステル共重合体、並びにポリアルキルスチレン等も例示できる。
【００５４】
これら粘度指数向上剤の分子量は、せん断安定性を考慮して選定することが必要である。具体的には、粘度指数向上剤の数平均分子量は、例えば分散型及び非分散型ポリメタクリレートでは５０００〜１００００００、好ましくは１０００００〜８０００００がよく、ポリイソブチレン又はその水素化物では８００〜５０００、エチレン−α−オレフィン共重合体又はその水素化物では８００〜３０００００、好ましくは１００００〜２０００００がよい。また、かかる粘度指数向上剤は、単独で又は複数種を任意に組合せて含有させることができるが、通常その含有量は、潤滑油組成物基準で０．１〜４０．０％であることが望ましい。
【００５５】
更にまた、他の無灰摩擦調整剤としては、ホウ酸エステル、高級アルコール、脂肪族エーテル等の無灰摩擦調整剤、ジチオリン酸モリブデン、ジチオカルバミン酸モリブデン、二硫化モリブデン等の金属系摩擦調整剤等が挙げられ、他の無灰分散剤としては、数平均分子量が９００〜３５００のポリブテニル基を有するポリブテニルベンジルアミン、ポリブテニルアミン、数平均分子量が９００未満のポリブテニル基を有するポリブテニルコハク酸イミド等及びそれらの誘導体等が挙げられる。
【００５６】
更にまた、上記磨耗防止剤又は極圧剤としては、ジスルフィド、硫化油脂、硫化オレフィン、炭素数２〜２０の炭化水素基を１〜３個含有するリン酸エステル、チオリン酸エステル、亜リン酸エステル、チオ亜リン酸エステル及びこれらのアミン塩等が挙げられる。
【００５７】
更にまた、上記防錆剤としては、アルキルベンゼンスルフォネート、ジノニルナフタレンスルフォネート、アルケニルコハク酸エステル、多価アルコールエステル等が挙げられ、上記非イオン系界面活性剤及び抗乳化剤としては、ポリオキシエチレンアルキルエーテル、ポリオキシエチレンアルキルフェニルエーテル、ポリオキシエチレンアルキルナフチルエーテル等のポリアルキレングリコール系非イオン系界面活性剤等が挙げられる。
【００５８】
更にまた、上記金属不活性化剤としては、イミダゾリン、ピリミジン誘導体、チアジアゾール、ベンゾトリアゾール、チアジアゾール等が挙げられ、上記消泡剤としては、シリコーン、フルオロシリコーン、フルオロアルキルエーテル等が挙げられる。
【００５９】
なお、これら添加剤を本発明の潤滑油組成物に含有させる場合には、その含有量は、組成物全量基準で、他の摩擦調整剤、他の無灰分散剤、磨耗防止剤又は極圧剤、防錆剤、及び抗乳化剤については０．０１〜５％、金属不活性剤については０．００５〜１％、消泡剤については０．０００５〜１％の範囲から適宜選択できる。
【００６０】
【実施例】
以下、本発明を実施例及び比較例により更に具体的に説明するが、本発明は、これら実施例のみに限定されるものではない。
【００６１】
（実施例１）
基材であるＳ４５Ｃ鋼から８×１２×４０ｍｍの半円柱形状を成す試験片を切り出し、この試験片の湾曲部の表面に、ＰＶＤアーク式イオンプレーティング法により、水素原子の量が０．５原子％以下であり、且つ、ヌープ硬度Ｈｋ＝２１７０ｋｇ／ｍｍ^２ 、Ｒｙ＝０．０３μｍ、厚さ０．５μｍのＤＬＣ薄膜を成膜し、本実施例の自動車用エンジンにおける摺動相手部材に相当する摺動試験片を製造した。そして、ボア部に相当する相手側試験片にはＦＣＡを用い、添加剤を含まない潤滑油中で摩擦摩耗試験を実施した。
【００６２】
（実施例２）
基材であるＳ４５Ｃ鋼から８×１２×４０ｍｍの半円柱形状を成す試験片を切り出し、この試験片の湾曲部の表面に、ＰＶＤアーク式イオンプレーティング法により、水素原子の量が０．５原子％以下であり、且つ、ヌープ硬度Ｈｋ＝２１７０ｋｇ／ｍｍ^２ 、Ｒｙ＝０．０３μｍ、厚さ０．５μｍのＤＬＣ薄膜を成膜し、本実施例の自動車用エンジンにおける摺動相手部材に相当する摺動試験片を製造した。そして、ボア部に相当する相手側試験片にはＦＣＡを用い、ベースオイルにエステル系無灰摩擦調整剤を添加した潤滑油中で摩擦摩耗試験を実施した。
【００６３】
（実施例３）
実施例２において、ボア部に相当する相手側試験片にシリンダボア部用の過共晶アルミニウム合金材を用い、エステル系添加剤を含む潤滑油中で摩擦摩耗試験を実施した。
【００６４】
（比較例１）
実施例１と同様にして切り出した摺動試験片の湾曲部の表面にめっき処理を施してＣｒ薄膜を成膜し、本比較例の自動車用エンジンにおける摺動相手部材に相当する摺動試験片とした。そして、添加剤を含まない潤滑油中で摩擦摩耗試験を実施した。
【００６５】
（比較例２）
比較例１において、ボア部に相当する相手側試験片にシリンダボア部用の過共晶アルミニウム合金材を用い、エステル系添加剤を含む潤滑油中で摩擦摩耗試験を実施した。
【００６６】
ここで、実施例及び比較例に用いた潤滑油の組成は表１の通りである。
潤滑油Ａ：実施例２，３及び比較例２
潤滑油Ｂ：実施例１及び比較例１
【００６７】
【表１】

【００６８】
［性能評価］
下記の試験条件下において、各例の摺動試験片に対して往復動試験を実施して、すなわち、図２に示すように、板状を成す相手側試験片１１上のＡの範囲で摺動試験片１０の湾曲部１０ａを荷重Ｐで相手側試験片１１に押し付けつつ矢印Ｑ，Ｒ方向に往復動させて、折り返し部での摩擦係数を測定した。得られた結果を表２に示す。
（試験条件）
摺動試験片 ：８×１２×４０ｍｍ 半円柱状試験片（Ｓ４５Ｃ）
相手側試験片 ：４０×６０×７ｍｍ 板状試験片（ＦＣＡ、過共晶Ａｌ合金）
試験装置 ：往復動試験装置
回転数 ：６００ｒｐｍ
試験温度 ：２５℃
押し付け荷重 ：１０ｋｇｆ
測定時間 ：６０ｍｉｎ後
【００６９】
【表２】

【００７０】
表２に示した結果から明らかなように、実施例１〜３の自動車用エンジンの摺動相手部材に相当する摺動試験片は、比較例１，２の自動車用エンジンの摺動相手部材に相当する摺動試験片と比較して、摩擦係数がそれぞれ格段に低いことから、いずれも耐スカッフ性に優れていることが立証された。特に、実施例３において摩擦係数が大幅に低減しており、摺動相手部材の硬質炭素薄膜とシリンダボア部用の過共晶アルミニウム合金とエステル系潤滑油との組合せとすることで、耐スカッフ性及び耐摩耗性のより一層の向上が期待できることが確認できた。その結果、本発明の自動車用エンジンにおいて、大幅なフリクションの低減を実現し得ることが確認された。
【００７１】
【発明の効果】
以上説明してきたように、本発明によれば、上記した構成としたため、耐スカッフ性及び耐摩耗性のいずれにも優れ、大幅なフリクション低減効果を発揮する自動車用エンジンを提供することが可能である。
【図面の簡単な説明】
【図１】本発明の自動車用エンジンのシリンダブロック及びピストンを示す断面説明図である。
【図２】実施例及び比較例の各摺動試験片に対する往復動試験の要領を示す斜視説明図である。
【符号の説明】
１ 自動車用エンジン
２ シリンダブロック
２ａ ボア部
３ａ ピストンスカート
４ ピストンリング
５ 硬質炭素薄膜[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an automobile engine having a cylinder block bore portion formed of a eutectic or hypereutectic aluminum alloy, and in particular, sliding that slides on the cylinder block bore portion in the presence of lubricating oil. The present invention relates to an automotive engine in which a mating member retains scuff resistance and friction resistance.
[0002]
[Prior art]
Conventionally, by adopting a cast iron cylinder liner in a cylinder block bore portion of an automobile engine, reliability is ensured and cost is reduced.
[0003]
However, in recent years, in consideration of weight reduction or thermal deformation during actual operation, an Al alloy cylinder liner having wear resistance and a liner in which the entire cylinder block is made of a hypereutectic Al alloy (A390 material). A less cylinder block has been developed (see, for example, Patent Document 1).
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 2003-13163
[Problems to be solved by the invention]
However, in the case of an engine having the above-described Al alloy cylinder liner or a hypereutectic (eutectic) Al alloy linerless cylinder block, it is effective in promoting weight reduction and suppressing thermal deformation during actual operation. However, there is a problem in that it is inferior in scuff resistance at low temperatures and corrosive wear as compared with an engine equipped with a conventional cast iron liner.
[0006]
In addition, sliding of the piston ring against the cylinder block bore and the sliding of the piston skirt in the presence of lubricating oil is the operation with the highest friction among the sliding parts of the automobile engine, reducing this friction. Although it is extremely important to reduce fuel consumption, even if the above-described Al alloy cylinder liner or hypereutectic (eutectic) Al alloy linerless cylinder block is used, There was a limit to reducing friction.
[0007]
OBJECT OF THE INVENTION
The present invention has been made in view of the above-described problems of the prior art, and can improve scuff resistance and wear resistance at low temperatures, and can achieve a significant reduction in friction. It aims to provide an engine for automobiles.
[0008]
[Means for Solving the Problems]
As a result of repeated investigations to achieve the above-mentioned problems, the present inventors have found the amount of hydrogen atoms contained in a hard carbon thin film that can exhibit extremely excellent low friction characteristics in the presence of lubricating oil, and the present invention. It came to complete.
[0009]
That is, the present invention is for an automobile including a cylinder block bore portion formed of a eutectic or hypereutectic aluminum alloy and a sliding counterpart member that slides against the cylinder block bore portion in the presence of lubricating oil. In the engine, a sliding portion of the sliding mating member with a cylinder block bore portion is covered with a hard carbon thin film, and the amount of hydrogen atoms contained in the hard carbon thin film is 1 atomic% or less.
[0010]
In the sliding counterpart member in the automobile engine of the present invention, the amount of hydrogen atoms contained in the hard carbon thin film coated on the sliding portion with the cylinder block bore portion is 1 atomic% or less. The sliding portion is sufficiently hard and has excellent adhesion resistance to aluminum. As a result, scuff resistance and wear resistance at low temperatures can be improved.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail. In the present specification, “%” indicates mass percentage unless otherwise specified.
[0012]
As shown in FIG. 1, an automobile engine 1 according to the present invention includes a cylinder block 2 formed of a eutectic or hypereutectic aluminum alloy, and a piston 3 made of a steel material or an aluminum material. In the bore portion 2a of the cylinder block 2, a piston ring 4 (top ring 4A, oil ring 4B) as a sliding counterpart member that slides with lubricating oil interposed is fitted and a piston skirt 3a is integrated. A hard carbon thin film 5 is coated on each sliding portion of the piston ring 4 and the bore portion 2a of the piston skirt 3a.
[0013]
In this case, the hard carbon thin film is desirably a DLC thin film (diamond-like carbon thin film) formed by various PVD methods, specifically, an arc ion plating method. This DLC thin film is an amorphous material mainly composed of carbon element, and specifically, a-C (amorphous carbon) composed only of carbon element, aC: H (hydrogen amorphous containing hydrogen). Carbon), and MeC (metal carbon or metal carbide) partially containing metal elements such as titanium (Ti) and molybdenum (Mo). From the viewpoint of exerting a significant friction reducing effect, the hydrogen content is The smaller the content, the better. The hydrogen content is 1% or less in terms of atomic ratio, more preferably the hydrogen content is 0.5% or less in terms of atomic ratio, and aC (amorphous carbon) material containing no hydrogen is suitable. Can be used.
[0014]
Here, when the surface roughness of the piston base material made of steel or aluminum material, that is, the surface roughness of the base material before coating the hard carbon thin film exceeds 0.03 μm, the roughness of the hard carbon thin film surface Since the protrusion due to the surface increases the local contact area with the counterpart material and induces cracking of the coating, the surface roughness of the substrate before coating the hard carbon thin film is 0.03 μm or less in Ra It is preferable that
[0015]
Next, the lubricating oil composition used in the present invention will be described in detail. This lubricating oil composition comprises a lubricating base oil containing a fatty acid ester-based ashless friction modifier and / or an aliphatic amine-based ashless friction modifier.
[0016]
The lubricating base oil is not particularly limited, and any type of base oil can be used as long as it is normally used as a base oil of a lubricating oil composition, such as mineral oil, synthetic oil, fats and oils, and mixtures thereof. be able to.
[0017]
As mineral oil, specifically, lubricating oil fraction obtained by atmospheric distillation and vacuum distillation of crude oil can be desolvated, solvent extraction, hydrocracking, solvent dewaxing, hydrorefining, sulfuric acid washing, clay treatment Paraffinic or naphthenic oils or normal paraffins, etc., which are refined by appropriately combining purification treatments such as the above, can be used, and those that have been subjected to solvent purification and hydrorefining treatment are common, but the aromatic content is further reduced It is more preferable to use an advanced hydrocracking process or GTL Wax (gas tow liquid wax) produced by isomerization.
[0018]
Specific examples of synthetic oils include poly-α-olefins (eg, 1-octene oligomers, 1-decene oligomers, ethylene-propylene oligomers), poly-α-olefin hydrides, isobutene oligomers, and isobutene oligomers. Hydride, isoparaffin, alkylbenzene, alkylnaphthalene, diester (eg, ditridecyl glutarate, dioctyl adipate, diisodecyl adipate, ditridecyl adipate, dioctyl sebacate, etc.), polyol ester (eg, trimethylolpropane caprylate, trimethylolpropane pelargol And trimethylolpropane esters such as trimethylolpropane isostearinate; pentaerythritol 2-ethylhexanoate, pentaerythritol Pentaerythritol esters such as largonate), polyoxyalkylene glycols, dialkyldiphenyl ethers, polyphenyl ethers and the like. Among them, preferred examples include poly-α-olefins such as 1-octene oligomers and 1-decene oligomers or hydrides thereof.
[0019]
The base oil of the lubricating oil composition used in the present invention is composed of two or more mineral base oils or two or more synthetic base oils, in addition to using a mineral base oil or a synthetic base oil alone or in combination. It can be a mixture. Further, the mixing ratio of two or more kinds of base oils in the above mixture is not particularly limited and can be arbitrarily selected.
[0020]
The sulfur content in the lubricating base oil is not particularly limited, but is preferably 0.2% or less, more preferably 0.1% or less, and even more preferably 0.05% or less, based on the total amount of the base oil. Preferably there is. In particular, since the sulfur content of hydrorefined mineral oil or synthetic base oil is 0.005% or less, or contains substantially no sulfur content (5 ppm or less), these are preferably used as the base oil.
[0021]
Further, the aromatic content in the lubricating base oil is not particularly limited, but in order to maintain a low friction characteristic for a long period of time as a lubricating oil composition for an internal combustion engine, the total aromatic content is 15% or less. Preferably, it is 10% or less, more preferably 5% or less. That is, when the total aromatic content of the lubricating base oil exceeds 15%, the oxidation stability is poor, which is not preferable.
[0022]
In addition, the total aromatic content said here means the aromatic fraction content measured based on the method prescribed | regulated to ASTMD2549.
[0023]
The kinematic viscosity of the lubricating base oil is not particularly limited, but when used as a lubricating oil composition for an internal combustion engine, the kinematic viscosity at 100 ° C. is preferably 2 mm ² / s or more, more preferably. 3 mm ² / s or more. On the other hand, the kinematic viscosity is preferably 20 mm ² / s or less, preferably 10 mm ² / s or less, and particularly preferably 8 mm ² / s or less. When the kinematic viscosity of the lubricating base oil at 100 ° C. is less than 2 mm ² / s, it is not preferable because sufficient abrasion resistance cannot be obtained and evaporation characteristics may be deteriorated. On the other hand, when the kinematic viscosity of the lubricating base oil at 100 ° C. exceeds 20 mm ² / s, it is not preferable because low friction performance is hardly exhibited and low temperature performance may be deteriorated. In the present invention, a mixture of any two or more base oils selected from the above base oils can be used, and the base oil alone is used as long as the kinematic viscosity at 100 ° C. falls within the above preferred range. Even if the kinematic viscosity is other than the above, it can be used.
[0024]
The viscosity index of the lubricating base oil is not particularly limited, but is preferably 80 or more, more preferably 100 or more, particularly when used as a lubricating oil composition for an internal combustion engine. 120 or more. By increasing the viscosity index of the lubricating base oil, it is possible to obtain a lubricating oil composition for an internal combustion engine that consumes less oil and has excellent low-temperature viscosity characteristics and fuel saving performance.
[0025]
The fatty acid ester ashless friction modifier and / or the aliphatic amine ashless friction modifier is a straight chain having 6 to 30 carbon atoms, preferably 8 to 24 carbon atoms, and particularly preferably 10 to 20 carbon atoms. Or the fatty acid ester which has a branched hydrocarbon group, a fatty-acid amine compound, and these arbitrary mixtures can be mentioned. When the carbon number is outside the range of 6 to 30, there is a possibility that the friction reducing effect cannot be obtained sufficiently.
[0026]
Specific examples of the straight chain or branched hydrocarbon group having 6 to 30 carbon atoms include hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group. Group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group, henocosyl group, docosyl group, tricosyl group, tetracosyl group, pentacosyl group, hexacosyl group, heptacosyl group, octacosyl group, nonacosyl group, triaconyl group, etc. Alkyl group, hexenyl group, heptenyl group, octenyl group, nonenyl group, decenyl group, undecenyl group, dodecenyl group, tridecenyl group, tetradecenyl group, pentadecenyl group, hexadecenyl group, heptadecenyl group, octadecenyl group, nonadecenyl group, icosenyl group, N'ikoseniru group include docosenyl, tricosenyl group, tetracosenyl group, Pentakoseniru group, Hekisakoseniru group, Heputakoseniru group, Okutakoseniru group, Nonakoseniru group, an alkenyl group such as tri container group. The alkyl group and alkenyl group include all possible linear structures and branched structures, and the position of the double bond in the alkenyl group is arbitrary.
[0027]
Moreover, as said fatty acid ester, the ester of the fatty acid which has this C6-C30 hydrocarbon group, and aliphatic monohydric alcohol or aliphatic polyhydric alcohol etc. can be illustrated, Specifically, glycerol monooleate, Particularly preferred examples include glycerine diolate, sorbitan monooleate, sorbitan diolate, and the like.
[0028]
Examples of the aliphatic amine compound include aliphatic monoamines or their alkylene oxide adducts, aliphatic polyamines, imidazoline compounds, and derivatives thereof. Specifically, fats such as laurylamine, lauryldiethylamine, lauryldiethanolamine, dodecyldipropanolamine, palmitylamine, stearylamine, stearyltetraethylenepentamine, oleylamine, oleylpropylenediamine, oleyldiethanolamine, N-hydroxyethyloleylimidazoline, etc. Amine alkylene compounds, amine alkylene oxide adducts such as N, N-dipolyoxyalkylene-N-alkyl (or alkenyl) (carbon number 6 to 28) of these aliphatic amine compounds, carbon numbers in these aliphatic amine compounds Residual amino group and / or imino by reacting 2-30 monocarboxylic acid (fatty acid, etc.) or polycarboxylic acid having 2-30 carbon atoms such as oxalic acid, phthalic acid, trimellitic acid, pyromellitic acid, etc. Base Some or amidated or neutralize all, so-called acid-modified compounds, and the like. Preferable examples include N, N-dipolyoxyethylene-N-oleylamine.
[0029]
Moreover, the content of the fatty acid ester ashless friction modifier and / or the aliphatic amine ashless friction modifier contained in the lubricating oil composition used in the present invention is 0.05 to 3. It is preferably 0%, more preferably 0.1 to 2.0%, and particularly preferably 0.5 to 1.4%. If the content is less than 0.05%, the friction reducing effect tends to be small, and if it exceeds 3.0%, the solubility and storage stability in the lubricating oil are significantly deteriorated, and precipitates are likely to be generated. It is not preferable.
[0030]
On the other hand, the lubricating oil composition used in the present invention preferably contains polybutenyl succinimide and / or a derivative thereof. Examples of the polybutenyl succinimide include the following general formula (1) and The compound represented by (2) is mentioned.
[0031]
[Chemical 1]

[0032]
[Chemical 2]

[0033]
PIB in these general formulas represents a polybutenyl group, and the number average molecular weight obtained by polymerizing a high purity isobutene or a mixture of 1-butene and isobutene with a boron fluoride catalyst or an aluminum chloride catalyst is 900 to 3500, preferably Obtained from 1000-2000 polybutene. When the number average molecular weight is less than 900, the cleanability effect tends to be poor, and when it exceeds 3500, the low temperature fluidity tends to be poor.
[0034]
Further, n in the above general formula is preferably an integer of 1 to 5, more preferably an integer of 2 to 4, from the viewpoint of excellent cleanliness. Further, the polybutene is used to remove a trace amount of fluorine and chlorine remaining due to a catalyst in the production process by an appropriate method such as an adsorption method or sufficient water washing, and is preferably 50 ppm or less, more preferably 10 ppm or less, and particularly preferably 1 ppm. It is also possible to use after removing to the following.
[0035]
Furthermore, the method for producing the polybutenyl succinimide is not particularly limited. For example, the polybutene chlorinated product or polybutene from which chlorine or fluorine is sufficiently removed and maleic anhydride are reacted at 100 to 200 ° C. The polybutenyl succinic acid thus obtained can be obtained by reacting with polyamines such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine and the like.
[0036]
On the other hand, as a derivative of the polybutenyl succinimide, a boron compound or an oxygen-containing organic compound is allowed to act on the compound represented by the general formula (1) or (2), thereby remaining amino groups and / or Examples thereof include so-called boron-modified or acid-modified compounds in which part or all of the imino group is neutralized or amidated. Among them, boron-containing polybutenyl succinimide, particularly boron-containing bispolybutenyl succinimide is most preferable.
[0037]
Examples of the boron compound include boric acid, borates, and borate esters. Specifically, examples of the boric acid include orthoboric acid, metaboric acid, and tetraboric acid. Moreover, as said borate, ammonium borate, such as ammonium salt etc., specifically, for example, ammonium metaborate, ammonium tetraborate, ammonium pentaborate, ammonium octaborate, etc. are mentioned as a suitable example. As the boric acid ester, an ester of boric acid and preferably an alkyl alcohol having 1 to 6 carbon atoms, more specifically, for example, monomethyl borate, dimethyl borate, trimethyl borate, monoethyl borate, boric acid Preferred examples include diethyl, triethyl borate, monopropyl borate, dipropyl borate, triplypropyl borate, monobutyl borate, dibutyl borate, tributyl borate and the like. In addition, the mass ratio “B / N” of the boron content B and the nitrogen content N in the boron-containing polybutenyl succinimide is usually 0.1 to 3, preferably 0.2 to 1. .
[0038]
Specific examples of the oxygen-containing organic compound include formic acid, acetic acid, glycolic acid, propionic acid, lactic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecyl. C1-C30 monocarboxylic acids such as acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, margaric acid, stearic acid, oleic acid, nonadecanoic acid, eicosanoic acid, oxalic acid, phthalic acid, C2-C30 polycarponic acid such as trimellitic acid and pyromellitic acid, and anhydrides or ester compounds thereof, C2-C6 alkylene oxide, hydroxy (poly) oxyalkylene carbonate and the like can be mentioned.
In the lubricating oil composition used in the present invention, the content of polybutenyl succinimide and / or its derivative is desirably 0.1 to 15%, and more desirably 1.0 to 12%. preferable. If it is less than 0.1%, the cleaning effect may be poor, and if it exceeds 15%, it is difficult to obtain a cleaning effect corresponding to the content, and the demulsibility tends to deteriorate.
[0040]
Furthermore, the lubricating oil composition used in the present invention preferably contains zinc dithiophosphate represented by the following general formula (3).
[0041]
[Chemical 3]

[0042]
R ⁴ , R ⁵ , R ⁶ and R ⁷ in the above formula (3) each independently represent a hydrocarbon group having 1 to 24 carbon atoms. Examples of these hydrocarbon groups include linear or branched alkyl groups having 1 to 24 carbon atoms, linear or branched alkenyl groups having 3 to 24 carbon atoms, and cycloalkyl groups having 5 to 13 carbon atoms. Or a linear or branched alkylcycloalkyl group, an aryl group having 6 to 18 carbon atoms, a linear or branched alkylaryl group, an arylalkyl group having 7 to 19 carbon atoms, or the like. It is desirable. The alkyl group or alkenyl group may be any of primary, secondary, and tertiary.
[0043]
Specific examples of R ⁴ , R ⁵ , R ⁶ and R ⁷ include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, and a decyl group. Undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group, heicosyl group, docosyl group, tricosyl group, tetracosyl group, alkyl group, propenyl group, Isopropenyl group, butenyl group, butadienyl group, pentenyl group, hexenyl group, heptenyl group, octenyl group, nonenyl group, decenyl group, undecenyl group, dodecenyl group, tridecenyl group, tetradecenyl group, pentadecenyl group, hexadecenyl group, heptadecenyl group, oleyl Octadeseni Group, nonadecenyl group, icocenyl group, heicosenyl group, dococenyl group, tricocenyl group, tetracocenyl group and other alkenyl groups, cyclopentyl group, cyclohexyl group, cycloheptyl group and other cycloalkyl groups, methylcyclopentyl group, dimethylcyclopentyl group, ethyl Cyclopentyl group, propylcyclopentyl group, ethylmethylcyclopentyl group, trimethylcyclopentyl group, diethylcyclopentyl group, ethyldimethylcyclopentyl group, propylmethylcyclopentyl group, propylethylcyclopentyl group, di-propylcyclopentyl group, propylethylmethylcyclopentyl group, methylcyclohexyl Group, dimethylcyclohexyl group, ethylcyclohexyl group, propylcyclohexyl group, ethylmethylcyclohexyl , Trimethylcyclohexyl group, diethylcyclohexyl group, ethyldimethylcyclohexyl group, propylmethylcyclohexyl group, propylethylcyclohexyl group, di-propylcyclohexyl group, propylethylmethylcyclohexyl group, methylcycloheptyl group, dimethylcycloheptyl group, Ethylcycloheptyl group, propylcycloheptyl group, ethylmethylcycloheptyl group, trimethylcycloheptyl group, diethylcycloheptyl group, ethyldimethylcycloheptyl group, propylmethylcycloheptyl group, propylethylcycloheptyl group, di-propylcycloheptyl group Alkylcycloalkyl groups such as propylethylmethylcycloheptyl group, aryl groups such as phenyl group and naphthyl group, tolyl group, xylyl group, Nyl group, propylphenyl group, ethylmethylphenyl group, trimethylphenyl group, butylphenyl group, propylmethylphenyl group, diethylphenyl group, ethyldimethylphenyl group, tetramethylphenyl group, pentylphenyl group, hexylphenyl group, heptylphenyl group , Alkylaryl groups such as octylphenyl group, nonylphenyl group, decylphenyl group, undecylphenyl group, dodecylphenyl group, benzyl group, methylbenzyl group, dimethylbenzyl group, phenethyl group, methylphenethyl group, dimethylphenethyl group, etc. An arylalkyl group etc. can be illustrated.
[0044]
The hydrocarbon groups that R ⁴ , R ⁵ , R ^6, and R ⁷ can include all possible linear structures and branched structures, and also include double bonds of alkenyl groups. The position, the bonding position of the alkyl group to the cycloalkyl group, the bonding position of the alkyl group to the aryl group, and the bonding position of the aryl group to the alkyl group are arbitrary. Further, among the hydrocarbon groups, when the hydrocarbon group is a linear or branched alkyl group having 1 to 18 carbon atoms, an aryl group having 6 to 18 carbon atoms, or a linear or branched group Particularly preferred is a linear alkylaryl group.
[0045]
Preferred examples of the zinc dithiophosphate include, for example, zinc diisopropyldithiophosphate, zinc diisobutyldithiophosphate, zinc di-sec-butyldithiophosphate, zinc di-sec-pentyldithiophosphate, zinc di-n-hexyldithiophosphate. , Zinc di-sec-hexyldithiophosphate, zinc di-octyldithiophosphate, zinc di-2-ethylhexyldithiophosphate, zinc di-n-decyldithiophosphate, zinc di-n-dodecyldithiophosphate, zinc diisotridecyldithiophosphate , And mixtures of these arbitrary combinations.
[0046]
Further, the content of the zinc dithiophosphate is preferably 0.1% or less, based on the total amount of the composition and in terms of phosphorus element, from the viewpoint of exerting a higher friction reduction effect, and 0.06% or less. It is more preferable that the zinc dithiophosphate is not contained. When the zinc dithiophosphate content exceeds 0.1% in terms of phosphorus element, the fatty acid ester-based ashless friction modifier and the aliphatic amine-based ashless friction on the sliding surface between the DLC member and the iron base member There exists a possibility that the outstanding friction reduction effect of a regulator may be inhibited.
[0047]
As a method for producing the zinc dithiophosphate, a conventional method can be arbitrarily adopted, and is not particularly limited. Specifically, for example, hydrocarbons corresponding to R ⁴ , R ⁵ , R ⁶ and R ⁷ are used. It can be synthesized by reacting a group-containing alcohol or phenol with phosphorus pentasulfide to dithiophosphoric acid and neutralizing it with zinc oxide. In addition, it cannot be overemphasized that the structure of the said zinc dithiophosphate changes with raw material alcohol to be used.
[0048]
In the present invention, two or more kinds of zinc dithiophosphates included in the general formula (3) may be mixed and used at an arbitrary ratio.
[0049]
As described above, in the automobile engine of the present invention, the lubricating oil composition has an extremely low friction when used in a sliding portion with a cylinder block bore portion of a sliding counterpart member coated with a hard carbon thin film. Although it exhibits the characteristics, it is particularly a metal detergent, antioxidant, viscosity index improver, other ashless friction modifier, other non-reactive agent for the purpose of enhancing the performance required as a lubricating oil composition for internal combustion engines. Ashes dispersant, antiwear agent or extreme pressure agent, rust inhibitor, nonionic surfactant, demulsifier, metal deactivator, antifoaming agent, etc. Can be increased.
[0050]
As said metallic detergent, the arbitrary compounds normally used as a metallic detergent for lubricating oil can be used. For example, alkali metal or alkaline earth metal sulfonates, phenates, salicylate naphthenates and the like can be used alone or in combination. Here, examples of the alkali metal include sodium (Na) and potassium (K), and examples of the alkaline earth metal include calcium (Ca) and magnesium (Mg). Specific preferred examples include Ca or Mg sulfonates, phenates and salicylates.
[0051]
In addition, the total base number and addition amount of these metal detergents can be arbitrarily selected according to the required performance of the lubricating oil. Usually, the total base number is 0 to 500 mgKOH / g, desirably 150 to 400 mgKOH / g by the perchloric acid method, and the addition amount is usually 0.1 to 10% based on the total amount of the composition.
[0052]
Further, as the antioxidant, any compound usually used as an antioxidant for lubricating oil can be used. For example, phenolic antioxidants such as 4,4′-methylenebis (2,6-di-tert-butylphenol), octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, phenyl Examples thereof include amine-based antioxidants such as -α-naphthylamine, alkylphenyl-α-naphthylamine, and alkyldiphenylamine, as well as mixtures according to any combination thereof. Moreover, the addition amount of this antioxidant is 0.01 to 5% normally on the basis of the total amount of the composition.
[0053]
Furthermore, as the above viscosity index improver, specifically, a so-called non-dispersion type viscosity index improver such as a copolymer of one or more monomers selected from various methacrylic acid esters and hydrogenated products thereof, Furthermore, a so-called dispersion type viscosity index improver obtained by copolymerizing various methacrylic acid esters containing a nitrogen compound can be exemplified. Specific examples of other viscosity index improvers include non-dispersed or dispersed ethylene-α-olefin copolymers (eg, α-olefins include propylene, 1-butene, 1-pentene, etc.) and hydrogen thereof. Examples thereof include a compound, polyisobutylene and a hydrogenated product thereof, a styrene-diene hydrogenated copolymer, a styrene-maleic anhydride ester copolymer, and a polyalkylstyrene.
[0054]
The molecular weight of these viscosity index improvers needs to be selected in consideration of shear stability. Specifically, the number average molecular weight of the viscosity index improver is, for example, 5,000 to 1,000,000, preferably 100,000 to 800,000 for dispersed and non-dispersed polymethacrylates, 800 to 5,000 for polyisobutylene or a hydride thereof, ethylene- In the case of an α-olefin copolymer or a hydride thereof, 800 to 300,000, preferably 10,000 to 200,000 is preferable. In addition, the viscosity index improver can be contained alone or in any combination of two or more, but the content is usually 0.1 to 40.0% based on the lubricating oil composition. desirable.
[0055]
Furthermore, other ashless friction modifiers include ashless friction modifiers such as boric acid esters, higher alcohols, aliphatic ethers, metal friction modifiers such as molybdenum dithiophosphate, molybdenum dithiocarbamate, and molybdenum disulfide. Examples of other ashless dispersants include polybutenylbenzylamine having a polybutenyl group having a number average molecular weight of 900 to 3,500, polybutenylamine, and polybutenyl succinic acid having a polybutenyl group having a number average molecular weight of less than 900. Examples thereof include acid imides and derivatives thereof.
[0056]
Furthermore, as the antiwear agent or extreme pressure agent, disulfide, sulfurized fat, sulfurized olefin, phosphate ester containing 1 to 3 hydrocarbon groups having 2 to 20 carbon atoms, thiophosphate ester, phosphite ester , Thiophosphite esters and amine salts thereof.
[0057]
Furthermore, examples of the rust inhibitor include alkyl benzene sulfonate, dinonyl naphthalene sulfonate, alkenyl succinate, polyhydric alcohol ester, and the like. Examples include polyalkylene glycol nonionic surfactants such as oxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, and polyoxyethylene alkyl naphthyl ether.
[0058]
Furthermore, examples of the metal deactivator include imidazoline, pyrimidine derivatives, thiadiazole, benzotriazole, thiadiazole, and examples of the antifoaming agent include silicone, fluorosilicone, and fluoroalkyl ether.
[0059]
In addition, when these additives are contained in the lubricating oil composition of the present invention, the content thereof is based on the total amount of the composition, and other friction modifiers, other ashless dispersants, antiwear agents or extreme pressure agents. The antirust agent and demulsifier can be appropriately selected from the range of 0.01 to 5%, the metal deactivator is 0.005 to 1%, and the antifoaming agent is 0.0005 to 1%.
[0060]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited only to these Examples.
[0061]
(Example 1)
A test piece having a semi-cylindrical shape of 8 × 12 × 40 mm was cut out from the S45C steel as a base material, and the amount of hydrogen atoms was 0.5 by the PVD arc type ion plating method on the surface of the curved portion of the test piece. Atomic% or less and Knoop hardness Hk = 2170 kg / mm ² A DLC thin film having a thickness of Ry = 0.03 μm and a thickness of 0.5 μm was formed, and a sliding test piece corresponding to a sliding counterpart member in the automobile engine of this example was manufactured. Then, FCA was used for the counterpart test piece corresponding to the bore portion, and a frictional wear test was performed in a lubricant containing no additive.
[0062]
(Example 2)
A test piece having a semi-cylindrical shape of 8 × 12 × 40 mm was cut out from the S45C steel as a base material, and the amount of hydrogen atoms was 0.5 by the PVD arc type ion plating method on the surface of the curved portion of the test piece. Atomic% or less and Knoop hardness Hk = 2170 kg / mm ² A DLC thin film having a thickness of Ry = 0.03 μm and a thickness of 0.5 μm was formed, and a sliding test piece corresponding to a sliding counterpart member in the automobile engine of this example was manufactured. Then, FCA was used for the counterpart test piece corresponding to the bore portion, and a frictional wear test was performed in a lubricating oil in which an ester-based ashless friction modifier was added to the base oil.
[0063]
Example 3
In Example 2, a hypereutectic aluminum alloy material for a cylinder bore part was used for the counterpart test piece corresponding to the bore part, and a frictional wear test was performed in a lubricating oil containing an ester-based additive.
[0064]
(Comparative Example 1)
The surface of the curved portion of the sliding test piece cut out in the same manner as in Example 1 was plated to form a Cr thin film, and the sliding test piece corresponding to the sliding counterpart member in the automobile engine of this comparative example It was. Then, a friction and wear test was performed in a lubricating oil containing no additive.
[0065]
(Comparative Example 2)
In Comparative Example 1, a hypereutectic aluminum alloy material for a cylinder bore was used for the counterpart test piece corresponding to the bore, and a frictional wear test was performed in a lubricating oil containing an ester-based additive.
[0066]
Here, the composition of the lubricating oil used in Examples and Comparative Examples is as shown in Table 1.
Lubricating oil A: Examples 2 and 3 and Comparative Example 2
Lubricating oil B: Example 1 and Comparative Example 1
[0067]
[Table 1]

[0068]
[Performance evaluation]
Under the following test conditions, a reciprocating test was performed on the sliding test piece of each example, that is, as shown in FIG. 2, the sliding test piece was slid in the range A on the mating test piece 11 having a plate shape. The bending portion 10a of the dynamic test piece 10 was reciprocated in the directions of arrows Q and R while being pressed against the counterpart test piece 11 with a load P, and the friction coefficient at the folded portion was measured. The obtained results are shown in Table 2.
(Test conditions)
Sliding test piece: 8 × 12 × 40 mm Semi-cylindrical test piece (S45C)
Counterpart test piece: 40 x 60 x 7 mm Plate test piece (FCA, hypereutectic Al alloy)
Test device: Reciprocating test device Rotational speed: 600 rpm
Test temperature: 25 ° C
Pressing load: 10kgf
Measurement time: 60 min later
[Table 2]

[0070]
As is clear from the results shown in Table 2, the sliding test pieces corresponding to the sliding counterpart members of the automotive engines of Examples 1 to 3 were used as the sliding counterpart members of the automotive engines of Comparative Examples 1 and 2. Compared to the corresponding sliding test pieces, each of the friction coefficients was remarkably low, so it was proved that each of them was excellent in scuff resistance. In particular, the friction coefficient in Example 3 is greatly reduced, and by using a combination of a hard carbon thin film as a sliding counterpart member, a hypereutectic aluminum alloy for the cylinder bore and an ester-based lubricant, scuff resistance It was also confirmed that further improvement in wear resistance can be expected. As a result, it was confirmed that the friction for the automobile engine of the present invention can be significantly reduced.
[0071]
【The invention's effect】
As described above, according to the present invention, since it has the above-described configuration, it is possible to provide an automobile engine that is excellent in both scuff resistance and wear resistance and exhibits a significant friction reduction effect. is there.
[Brief description of the drawings]
FIG. 1 is a cross-sectional explanatory view showing a cylinder block and a piston of an automobile engine of the present invention.
FIG. 2 is a perspective explanatory view showing the point of a reciprocating test for each sliding test piece of an example and a comparative example.
[Explanation of symbols]
1 Automotive Engine 2 Cylinder Block 2a Bore 3a Piston Skirt 4 Piston Ring 5 Hard Carbon Thin Film

Claims (10)

In an automotive engine comprising a cylinder block bore formed of a eutectic or hypereutectic aluminum alloy and a sliding counterpart member that slides against the cylinder block bore in the presence of lubricating oil, the sliding An automobile engine characterized in that a sliding portion of a mating member with a cylinder block bore is covered with a hard carbon thin film, and the amount of hydrogen atoms contained in the hard carbon thin film is 1 atomic% or less. The automobile engine according to claim 1, wherein the sliding member is a piston ring and / or a piston skirt. The automobile engine according to claim 1 or 2, wherein the amount of hydrogen atoms contained in the hard carbon thin film is 0.5 atomic% or less. The automobile engine according to any one of claims 1 to 3, wherein the lubricating oil contains a fatty acid ester-based ashless friction modifier and / or an aliphatic amine-based ashless friction modifier. The fatty acid ester-based ashless friction modifier and / or the aliphatic amine-based ashless friction modifier of the lubricating oil has a hydrocarbon group having 6 to 30 carbon atoms and is 0.05 to 3.3 based on the total amount of the composition. The automobile engine according to claim 4, containing 0%. The automobile engine according to any one of claims 1 to 5, wherein the lubricating oil contains polybutenyl succinimide and / or a derivative thereof. The automobile engine according to claim 6, wherein the content of polybutenyl succinimide and / or its derivative is 0.1 to 15% based on the total amount of the composition. The automobile engine according to any one of claims 1 to 7, wherein the lubricating oil contains 0.1% or less of zinc dithiophosphate in terms of the total amount of the composition and in terms of phosphorus element. The automobile engine according to any one of claims 1 to 8, wherein the DLC thin film formed by the PVD method is a hard carbon thin film. The automobile engine according to any one of claims 1 to 9, wherein the surface roughness of the base material before coating with the hard carbon thin film is set to 0.03 µm or less in terms of Ra.

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