JP2004183815A - Bearing device for wheel - Google Patents

Bearing device for wheel Download PDF

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Publication number
JP2004183815A
JP2004183815A JP2002352724A JP2002352724A JP2004183815A JP 2004183815 A JP2004183815 A JP 2004183815A JP 2002352724 A JP2002352724 A JP 2002352724A JP 2002352724 A JP2002352724 A JP 2002352724A JP 2004183815 A JP2004183815 A JP 2004183815A
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Prior art keywords
inner ring
ring
hub
wheel
row
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Pending
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JP2002352724A
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Japanese (ja)
Inventor
Hisashi Otsuki
寿志 大槻
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NTN Corp
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NTN Corp
NTN Toyo Bearing Co Ltd
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Priority to JP2002352724A priority Critical patent/JP2004183815A/en
Publication of JP2004183815A publication Critical patent/JP2004183815A/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/30—Parts of ball or roller bearings
    • F16C33/58—Raceways; Race rings
    • F16C33/64—Special methods of manufacture
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/30—Parts of ball or roller bearings
    • F16C33/34—Rollers; Needles
    • F16C33/36—Rollers; Needles with bearing-surfaces other than cylindrical, e.g. tapered; with grooves in the bearing surfaces
    • F16C33/366—Tapered rollers, i.e. rollers generally shaped as truncated cones
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/30—Parts of ball or roller bearings
    • F16C33/58—Raceways; Race rings
    • F16C33/62—Selection of substances
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C19/00—Bearings with rolling contact, for exclusively rotary movement
    • F16C19/22—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings
    • F16C19/34—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for both radial and axial load
    • F16C19/38—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for both radial and axial load with two or more rows of rollers
    • F16C19/383—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for both radial and axial load with two or more rows of rollers with tapered rollers, i.e. rollers having essentially the shape of a truncated cone
    • F16C19/385—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for both radial and axial load with two or more rows of rollers with tapered rollers, i.e. rollers having essentially the shape of a truncated cone with two rows, i.e. double-row tapered roller bearings
    • F16C19/386—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for both radial and axial load with two or more rows of rollers with tapered rollers, i.e. rollers having essentially the shape of a truncated cone with two rows, i.e. double-row tapered roller bearings in O-arrangement
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C2202/00—Solid materials defined by their properties
    • F16C2202/02—Mechanical properties
    • F16C2202/04—Hardness
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C43/00—Assembling bearings
    • F16C43/04—Assembling rolling-contact bearings

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Rolling Contact Bearings (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To achieve long service life of an inner ring on the inner side where load conditions are strict, secure strength of conical rollers in an inner row, improve strength of a flange part of a hub ring, reduce flange deformation quantity when a vehicle turns, and improve rigidity and strength around wheels. <P>SOLUTION: This bearing device for a wheel is of a hub unit type, and of a plurality row conical roller bearing type. The inner ring 3 is engaged with an inner ring engagement surface 2a provided at one end of the hub ring 2, and inner side and outer side inner ring race surfaces 2b are provided in the inner ring 3 and the hub ring 2. The hub ring 2 is composed of carbon steel. A hard layer 20 of surface hardness of 58-60HRC is provided on a surface part of the hub ring 2 from the inner ring engagement surface 2a to a flange root part 22a. The inner ring 3 on the inner side and the conical rollers 5 are composed of bearing steel treated with through quenching to have surface hardness of 60HRC or more. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
この発明は、ハブユニット形式の車輪用軸受装置に関し、特に、トラック，ワゴン車等における比較的負荷容量の大きい車輪用軸受装置や、一般乗用車の車輪用軸受装置に関する。
【０００２】
【従来の技術】
アンギュラ玉軸受を用いる乗用車用の車輪用軸受装置は、第１世代と呼ばれるシール付き複列軸受を単独で使用するものから、外輪がフランジ付きのハブを兼ねるハブユニット軸受となった第２世代のものへと進化し、さらに内外輪共にフランジを有する第３世代のものから、等速ジョイントを一体化した第４世代のものまで開発されている。第３世代のものでは、複列軸受における片列の内輪軌道面をハブ輪に直接に形成し、もう片列の内輪軌道面は、ハブ輪と別体に形成されてハブ輪に嵌合する内輪により形成している。
円すいころ軸受を用いる車輪用軸受装置は、トラック等に用いられるために、比較的コンパクト化の要望が少なくて、開発が遅れており、外輪がフランジ付きのハブを兼ね、ハブユニット軸受となった第２世代のものまでしか開発されるに至っていない。
一方、いわゆるワンボックスカー等のワゴン車の需要が増大し、多機能化が求められていることから、円すいころ軸受が必要な負荷容量の大きな車輪用軸受装置においても、一体化，コンパクト化が望まれようになってきている。
【０００３】
そこで、本発明者等は、図４に示すように、円すいころ軸受を用いる車輪用軸受装置において、内輪となるハブ輪２と、フランジ付きの外輪４とを有する第３世代に相当するハブユニット形式の車輪用軸受装置を開発した（例えば特許文献１）。この形式の車輪用軸受装置受は、ハブ輪２に片列の内輪軌道面２ｂ２を直接に形成すると共に、ハブ輪２のインナー側端に別体の内輪３を嵌合させて、もう片列の内輪軌道面２ｂ１を形成している。
【０００４】
また、ハブ輪２の表面部における内輪軌道面２ｂ１，２ｂ２からフランジ２２の根元部２２ａにわたる部分を、高周波熱処理による硬化層２０としている。これにより、肉厚の増加や工程増加を伴うことなく、ハブ輪２のフランジ部２２の強度を向上させることができて、車両旋回時のフランジ変形量を低下させることができ、車輪回りの剛性，強度の向上が図れる。
【０００５】
【特許文献１】
特開平１１−５１０６４号公報
【０００６】
【発明が解決しようとする課題】
図４のような車輪用軸受装置においては、タイヤ接地面から車体重量および旋回横荷重がハブ輪２を介して円すいころ５および内外の軌道面２ｂ１，２ｂ２，４ｂ１，４ｂ２に負荷される。このとき、アウター列の軌道面２ｂ２，４ｂ２よりもインナー列の軌道面２ｂ１，４ｂ１の方が荷重の負荷率が大きく、また円すいころ５と外輪軌道面４ｂ１，４ｂ２の面圧よりも、円すいころ５と内輪軌道面２ｂ１，２ｂ２の面圧の方が大きくなる。そのため、転がり疲労寿命はインナー側の内輪３が最も低下する。また、縁石乗り上げ等の大きな横荷重が負荷された場合には、インナー列の円すいころ５の負荷が厳しくなる。
しかし、上記構成の車輪用軸受装置に限らず、これまでのハブユニット形式の車輪用軸受装置では、インナー側の内輪および円すいころは、表面に浸炭層（表面硬さ５８ＨＲＣ以上，浸炭深さ１〜２ｍｍ程度）を施した浸炭鋼（例えばＪＩＳ規格のＳＣＲ，ＳＣＭ，ＳＮＣＭ相当）を材料として使用しているので、上記したインナー側の内輪３の寿命低下や、インナー列の円すいころ５の寿命低下を防止できないという問題点が有った。
【０００７】
この発明の目的は、インナー側の内輪の長寿命化およびインナー列の円すいころの強度確保が可能で、かつハブ輪のフランジ部の強度向上、車両旋回時のフランジ変形量低下、車輪回りの剛性，強度の向上が図れるハブユニット形式の車輪用軸受装置を提供することである。
【０００８】
【課題を解決するための手段】
この発明の車輪用軸受装置は、ハブ輪と外輪とを備えるハブユニット形式の車輪用軸受装置である。ハブ輪は、複列の円すいころ軸受の片列の内輪を嵌合させる内輪嵌合面を一端外周に有し、この内輪嵌合面に隣接して他の片列の内輪軌道面を有し、かつ他端にフランジを有する。このハブ輪と外輪との間に保持器に保持された円すいころを介在させる。上記ハブ輪は炭素鋼製とし、このハブ輪の表面部における上記内輪嵌合面からフランジ根元部にわたる部分に、表面硬さ５８〜６０ＨＲＣの硬化層を設ける。上記片列の内輪および円すいころは、表面硬さ６０ＨＲＣ以上のずぶ焼き入れの施された軸受鋼とする。
この種の車輪用軸受装置は、タイヤ接地面より車体重量および旋回横荷重が軌道面に負荷される負荷率が、アウター列の軌道面よりも大きくなる。しかし、この構成の車輪用軸受装置によると、インナー側の内輪および円すいころを、表面硬さ６０ＨＲＣ以上のずぶ焼き入れの施された軸受鋼としたため、インナー列の内輪軌道面を有する内輪の長寿命化が可能となり、また縁石乗り上げ等の大きな横荷重が負荷されたときでも、インナー側列の円すいころに、内部割れ等に対する十分な強度が確保される。また、ハブ輪の内輪嵌合面からフランジ根元部にわたる部分に、表面硬さ５８〜６０ＨＲＣの硬化層が設けられているため、フランジ部の硬度が向上し、車両旋回時のフランジ変形量が低下する。そのため、車両の車輪回りの剛性の向上となる。
【０００９】
この発明において、上記外輪を炭素鋼製とし、その外輪の軌道面の部分にも、表面硬さ５８〜６０ＨＲＣの硬化層を設けても良い。この構成の場合、外輪の長寿命化も可能となる。
【００１０】
この発明において、上記ハブ輪の内輪嵌合面のさらに端部側に、上記片列の内輪の幅面を押し付けるフランジ状の加締部を有し、上記内輪嵌合面の上記硬化層を設ける範囲は、上記加締部の近傍まで、すなわち加締部に達しない範囲としても良い。このように構成した場合は、ハブ輪の硬化層が、ハブ輪の一端を加締めて内輪を軸方向に締め付け固定する妨げにならない。
【００１１】
【発明の実施の形態】
この発明の一実施形態を図１ないし図３と共に説明する。この車輪用軸受装置は、ハブユニット形式でかつ複列円すいころ軸受形式としたものである。この車輪用軸受装置１は、駆動輪の支持に適用した例であって、ハブ輪２と外輪４とを備える。ハブ輪２は、片列の別体の内輪３を嵌合させる内輪嵌合面２ａを一端外周に有し、この内輪嵌合面２ａに隣接して他の片列の内輪軌道面２ｂを有しており、他端外周に車輪取付用のフランジ２２を有する。上記一端はインナー側となり、他端はアウター側となる。内輪嵌合面２ａと内輪軌道面２ｂとの間には、内輪３の小径端が嵌まり込む深さの段差が形成されている。別体の内輪３は、片列の内輪軌道面２ｂを形成した部材である。両列の円すいころ５は、互いに小径端が対向するように配置され、各列毎に保持器６により保持される。ハブ輪２および内輪３は、それぞれの内輪軌道面２ｂに隣接して、大端側の鍔部のみが設けられて小径端側は鍔無しとされている。ハブ輪２の内輪嵌合面２ａよりもさらに端部側は、内輪３の幅面を押し付けるフランジ状の加締部２ｃとされており、この加締部２ｃにより内輪３が軸方向に締め付け固定される。ハブ輪２は、このような加締部２ｃを有しないものであっても良く、その場合は圧入やナットの締め込み、その他適宜の構成で内輪３を固定する。外輪４は、両列の外輪軌道面４ｂ，４ｂを有する軌道輪であり、外径面にフランジからなる取付部４ａが設けられる。外輪４は、軌道面４ｂに隣接する鍔部は、大端側および小端側の両方とも有しない。外輪４の両端に、内外輪間を密封するオイルシール等のシール７が設けられている。
【００１２】
図２に示すように、外輪４は、取付部４ａの孔を貫通するナックルボルト１０により、車体側の懸架装置におけるナックル２５に取付けられる。
ハブ輪２には、フランジ２２の孔を貫通するハブボルト８、およびこのハブボルト８に螺合するハブナット９により、ブレーキロータ２３および車輪２４のタイヤホイール２４ａがフランジ２２に取付けられる。ハブ輪２には、等速自在継手１１の一端（例えば外輪）が連結され、その他端（例えば内輪）が駆動軸（図示せず）に連結される。
【００１３】
ハブ輪２は、炭素鋼製（ＪＩＳ規格のＳ５０Ｃ〜Ｓ７０Ｃ相当）であり、その外径側の表面部における内輪嵌合面２ａからフランジ根元部２２ａにわたる部分に、高周波熱処理により所定の深さの硬化層２０が設けられている。上記内輪嵌合面２ａの部分における硬化層２０を設ける範囲は、上記加締部２ｃの近傍つまり加締部２ｃに達しない範囲とされている。また、外輪４も、同じ炭素鋼製であり、その両列の軌道面４ｂ，４ｂとなる内径側の表面部に、高周波熱処理により所定の深さの硬化層２１が設けられている。上記各硬化層２０，２１の表面硬さは５８〜６０ＨＲＣとされている。インナー側列の内輪３および円すいころ５は、ずぶ焼き入れの施された軸受鋼製（ＪＩＳ規格のＳＵＪ相当）とされており、その焼入れ部分の表面硬さは６０ＨＲＣ以上とされている。アウター側の円すいころ５も、インナー側の円すいころ５と同じずぶ焼き入れの施された軸受鋼製とされるが、インナー側の円すいころ５は、従来例と同様に浸炭鋼製としても良い。
【００１４】
図３は、この車輪用軸受装置１の組立工程を示す。まず、単体の外輪４（図３（Ａ））に、円すいころ５と保持器６の組み立て部品１５を組み込み（同図（Ｂ））、そのアウター側にシール７を組み込む（同図（Ｃ））。このように組み立てた部品に、ハブ輪２を組み込み（同図（Ｄ））、このハブ輪２に片列の内輪３を組み込んでから（同図（Ｅ））、インナー側にシール７を組み込み（同図（Ｆ））ハブ輪２の一端（インナー側端）を加締める。これにより、内輪３の幅面を押し付ける加締部２ｃを形成することで（同図（Ｇ））、図１のように車輪用軸受装置１が完成する。
【００１５】
この構成の車輪用軸受装置によると、この種の軸受の特性として、インナー側の内輪軌道面２ｂ、つまり内輪３の軌道面２ｂは、タイヤ接地面より車体重量および旋回横荷重が軌道面に負荷される負荷率が、アウター列の軌道面２ｂよりも大きくなる。しかし、内輪３は、ずぶ焼き入れの施された表面硬さ６０ＨＲＣ以上の軸受鋼製とされているため、このような大きな負荷率に対しても、インナー列の内輪軌道面２ｂを有する内輪３の長寿命化が可能となる。従来、インナー側の内輪には浸炭層を施した軸受鋼が用いられているが、近年、ずぶ焼き入れにした軸受鋼は、精錬法の改善により、挟雑物が少なく浸炭鋼以上の疲労寿命が得られており、厳しい面圧下でも長寿命が図れることが判った。
また、インナー列の円すいころ５も、内輪３と同じく、ずぶ焼き入れの施された表面硬さ６０ＨＲＣ以上の軸受鋼製としたため、大きな負荷率にかかわらず、強度的に優れたものとなる。この円すいころ５は、浸炭鋼の内部硬さ（３８ＨＲＣ以下）に比べて軸受鋼の硬さが硬く、内部割れに対して強い。このため、縁石乗り上げ等の大きな横荷重が負荷されたときでも、インナー側列の円すいころ５に内部割れが発生することが防止される。
なお、軸受の転がり寿命は、硬さの他に表面の残留圧縮応力の関係やオーステナイト量との関係などが影響するため、一概に硬さだけでは論じられないが、一般的には硬さが低いほど転がり寿命が短く、例えば同一材料の鋼材で、５８ＨＲＣに対して６０ＨＲＣとしたものは、１．８倍程度の寿命が得られるデータもある。
【００１６】
また、ハブ輪２が炭素鋼製で、そのハブ輪２の外径表面部における内輪嵌合面２ａからフランジ根元部２２ａにわたる部分に、表面硬さ５８〜６０ＨＲＣの硬化層２０を設けているので、フランジ２２の部分の硬度が向上し、車両旋回時のフランジ２２の変形量が低下する。そのため、車両の車輪回りの剛性の向上となる。また、ハブ輪２の硬化層２０は内輪嵌合面２ａまで拡大されているため、内輪３の内径面とハブ輪２の外径面とに発生するフレッティング摩耗を最小限に抑えることができる。そのため、フレッティング摩耗の発生により、内輪３とハブ輪２の嵌合面に、錆、摩耗粉、かじり等が生じて、内輪３を損傷するということがなく、耐久性を向上させることができる。
【００１７】
外輪４についても、炭素鋼製で、その両列の外輪軌道面４ｂ，４ｂとなる内径側の表面部に表面硬さ５８〜６０ＨＲＣの硬化層２１を設けていることから、外輪４の長寿命化も可能となる。
【００１８】
なお、上記実施形態は駆動輪を支持する車輪用軸受装置１に適用した場合につき説明したが、この発明は、従動輪を支持する車輪用軸受装置にも適用することができる。
【００１９】
【発明の効果】
この発明の車輪用軸受装置は、ハブ輪が、複列の円すいころ軸受の片列の内輪を嵌合させる内輪嵌合面を一端外周に有し、この内輪嵌合面に隣接して他の片列の内輪軌道面を有し、かつ他端にフランジを有し、このハブ輪と外輪との間に保持器に保持された円すいころを介在させ、上記ハブ輪を炭素鋼製とし、このハブ輪の表面部における上記内輪嵌合面からフランジ根元部にわたる部分に、表面硬さ５８〜６０ＨＲＣの硬化層を設け、上記片列の内輪および円すいころを、表面硬さ６０ＨＲＣ以上のずぶ焼き入れの施された軸受鋼としたため、インナー側の内輪の長寿命化およびインナー列の円すいころの強度確保が可能で、かつハブ輪のフランジ部の強度向上、車両旋回時のフランジ変形量低下、車輪回りの剛性，強度の向上が図れる。
【図面の簡単な説明】
【図１】この発明の一実施形態にかかる車輪用軸受装置の断面図である。
【図２】同車輪用軸受装置による駆動輪支持構造を示す断面図である。
【図３】同車輪用軸受装置の組み立て過程の工程説明図である。
【図４】従来例の断面図である。
【符号の説明】
１…車輪用軸受装置
２…ハブ輪
２ａ…内輪嵌合面
２ｂ…内輪軌道面
２ｃ…加締部
３…内輪
４…外輪
４ｂ…外輪軌道面
５…円すいころ
６…保持器
２０…ハブ輪の硬化層
２１…外輪の硬化層
２２…ハブ輪のフランジ
２２ａ…フランジ根元部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wheel bearing device of a hub unit type, and more particularly to a wheel bearing device having a relatively large load capacity in a truck, a wagon car or the like, or a wheel bearing device for a general passenger car.
[0002]
[Prior art]
Wheel bearings for passenger cars that use angular contact ball bearings, which use single-row sealed double-row bearings, called the first generation, have been changed to the second generation, where the outer ring has become a hub unit bearing that also serves as a flanged hub. From the 3rd generation, which has evolved into a product and has flanges on both the inner and outer rings, the 4th generation has been developed. In the third generation, the inner ring raceway surface of one row in the double row bearing is formed directly on the hub wheel, and the inner ring raceway surface of the other row is formed separately from the hub wheel and is fitted to the hub wheel. It is formed by an inner ring.
Since wheel bearing devices using tapered roller bearings are used in trucks, etc., there is little demand for relatively compact design, and development has been delayed. The outer ring also serves as a hub with a flange, resulting in a hub unit bearing. Only the second generation has been developed.
On the other hand, the demand for wagons such as so-called one-box cars is increasing, and there is a demand for multi-functionality. Therefore, even in wheel bearing devices with large load capacity that require tapered roller bearings, integration and downsizing are possible. It is becoming desirable.
[0003]
Therefore, the present inventors, as shown in FIG. 4, in a wheel bearing device using a tapered roller bearing, a hub unit corresponding to a third generation having a hub ring 2 as an inner ring and an outer ring 4 with a flange. A wheel bearing device of the type has been developed (for example, Patent Document 1). In this type of wheel bearing device receiver, a single row of inner ring raceway surfaces 2b2 is formed directly on the hub wheel 2, and a separate inner ring 3 is fitted to the inner side end of the hub wheel 2, so that the other row The inner ring raceway surface 2b1 is formed.
[0004]
Further, a portion extending from the inner ring raceway surfaces 2b1 and 2b2 to the root portion 22a of the flange 22 in the surface portion of the hub wheel 2 is a hardened layer 20 by high frequency heat treatment. As a result, the strength of the flange portion 22 of the hub wheel 2 can be improved without increasing the wall thickness or increasing the number of processes, the amount of flange deformation during turning of the vehicle can be reduced, and the rigidity around the wheel can be reduced. , Strength can be improved.
[0005]
[Patent Document 1]
JP-A-11-51064 [0006]
[Problems to be solved by the invention]
In the wheel bearing device as shown in FIG. 4, the weight of the vehicle body and the turning lateral load are applied to the tapered roller 5 and the inner and outer raceway surfaces 2 b 1, 2 b 2, 4 b 1 and 4 b 2 through the hub wheel 2. At this time, the inner row raceway surfaces 2b1 and 4b1 have a larger load factor than the outer row raceway surfaces 2b2 and 4b2, and the tapered rollers have a larger load ratio than the tapered rollers 5 and the outer ring raceway surfaces 4b1 and 4b2. 5 and the inner ring raceway surfaces 2b1 and 2b2 have a larger surface pressure. For this reason, the rolling fatigue life of the inner ring 3 on the inner side is the lowest. Further, when a large lateral load such as curb ride is applied, the load on the tapered roller 5 in the inner row becomes severe.
However, the present invention is not limited to the wheel bearing device of the above configuration, and in the conventional hub unit type wheel bearing device, the inner ring and the tapered roller on the inner side have a carburized layer (surface hardness of 58 HRC or more, carburization depth 1). Carburized steel (equivalent to JIS standard SCR, SCM, SNCM) is used as a material, so that the life of the inner ring 3 on the inner side and the life of the tapered roller 5 in the inner row are reduced. There was a problem that the decline could not be prevented.
[0007]
The object of the present invention is to extend the service life of the inner ring on the inner side and to ensure the strength of the tapered rollers in the inner row, to improve the strength of the flange portion of the hub wheel, to reduce the amount of flange deformation when turning the vehicle, and to provide rigidity around the wheel. It is to provide a hub unit type wheel bearing device capable of improving strength.
[0008]
[Means for Solving the Problems]
The wheel bearing device of the present invention is a hub unit type wheel bearing device including a hub wheel and an outer ring. The hub ring has an inner ring fitting surface on one outer periphery for fitting one row of inner rings of a double row tapered roller bearing, and has another inner row raceway surface adjacent to the inner ring fitting surface. And having a flange at the other end. A tapered roller held by a cage is interposed between the hub ring and the outer ring. The hub ring is made of carbon steel, and a hardened layer having a surface hardness of 58 to 60 HRC is provided on the surface portion of the hub ring extending from the inner ring fitting surface to the flange root portion. The single-row inner ring and the tapered roller are made of bearing steel having a surface hardness of 60 HRC or higher.
In this type of wheel bearing device, the load factor at which the vehicle body weight and the turning lateral load are applied to the raceway surface from the tire ground contact surface is larger than that of the outer row raceway surface. However, according to the wheel bearing device of this configuration, since the inner ring and the tapered roller on the inner side are made of bearing steel that has been subjected to continuous quenching with a surface hardness of 60 HRC or more, the length of the inner ring having the inner ring raceway surface of the inner row The service life can be extended, and even when a large lateral load such as curb climbing is applied, the tapered rollers in the inner side row have sufficient strength against internal cracks. In addition, since a hardened layer with a surface hardness of 58-60 HRC is provided in the part from the inner ring fitting surface of the hub wheel to the flange root part, the hardness of the flange part is improved, and the amount of flange deformation during vehicle turning is reduced. To do. Therefore, the rigidity around the vehicle wheel is improved.
[0009]
In the present invention, the outer ring may be made of carbon steel, and a hardened layer having a surface hardness of 58 to 60 HRC may be provided on the raceway surface of the outer ring. In the case of this configuration, the life of the outer ring can be extended.
[0010]
In this invention, there is a flange-shaped crimping portion that presses the width surface of the inner ring of the single row on the further end side of the inner ring fitting surface of the hub wheel, and the hardened layer of the inner ring fitting surface is provided. May be in the vicinity of the crimped portion, that is, a range not reaching the crimped portion. In such a configuration, the hardened layer of the hub ring does not hinder the inner ring from being tightened and fixed in the axial direction by caulking one end of the hub ring.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIGS. This wheel bearing device is a hub unit type and a double row tapered roller bearing type. This wheel bearing device 1 is an example applied to support of a drive wheel, and includes a hub wheel 2 and an outer ring 4. The hub wheel 2 has an inner ring fitting surface 2a for fitting a separate inner ring 3 in one row at one end outer periphery, and has another inner row raceway surface 2b adjacent to the inner ring fitting surface 2a. It has a flange 22 for wheel attachment on the outer periphery of the other end. The one end is the inner side and the other end is the outer side. Between the inner ring fitting surface 2a and the inner ring raceway surface 2b, a step having a depth to which the small diameter end of the inner ring 3 is fitted is formed. The separate inner ring 3 is a member formed with a single row of inner ring raceway surfaces 2b. The tapered rollers 5 in both rows are arranged so that the small diameter ends face each other, and are held by the cage 6 for each row. The hub ring 2 and the inner ring 3 are adjacent to the inner ring raceway surface 2b, only the large end side flange portion is provided, and the small diameter end side is free of wrinkles. Further, the end side of the hub ring 2 from the inner ring fitting surface 2a is a flange-shaped caulking portion 2c that presses the width surface of the inner ring 3. The inner ring 3 is clamped and fixed in the axial direction by the caulking portion 2c. The The hub wheel 2 may not have such a caulking portion 2c. In that case, the inner ring 3 is fixed by press fitting, nut tightening, or other appropriate configurations. The outer ring 4 is a bearing ring having both rows of outer ring raceway surfaces 4b, 4b, and a mounting portion 4a made of a flange is provided on the outer diameter surface. In the outer ring 4, the flange adjacent to the raceway surface 4 b does not have both the large end side and the small end side. Seals 7 such as oil seals for sealing between the inner and outer rings are provided at both ends of the outer ring 4.
[0012]
As shown in FIG. 2, the outer ring 4 is attached to the knuckle 25 in the suspension device on the vehicle body side by the knuckle bolt 10 that passes through the hole of the attachment portion 4 a.
The brake wheel 23 and the tire wheel 24 a of the wheel 24 are attached to the flange 22 by the hub bolt 8 that passes through the hole of the flange 22 and the hub nut 9 that is screwed into the hub bolt 8. One end (for example, an outer ring) of the constant velocity universal joint 11 is connected to the hub wheel 2, and the other end (for example, an inner ring) is connected to a drive shaft (not shown).
[0013]
The hub wheel 2 is made of carbon steel (equivalent to S50C to S70C of JIS standard), and a portion of the outer diameter side surface portion extending from the inner ring fitting surface 2a to the flange root portion 22a has a predetermined depth by high-frequency heat treatment. A hardened layer 20 is provided. The range in which the hardened layer 20 is provided in the inner ring fitting surface 2a is set in the vicinity of the caulking portion 2c, that is, the range not reaching the caulking portion 2c. The outer ring 4 is also made of the same carbon steel, and a hardened layer 21 having a predetermined depth is provided by high-frequency heat treatment on a surface portion on the inner diameter side that becomes the raceway surfaces 4b and 4b of both rows. The surface hardness of each of the cured layers 20 and 21 is 58 to 60 HRC. The inner ring 3 and the tapered roller 5 in the inner side row are made of bearing steel that has been subjected to excessive quenching (equivalent to SUJ of JIS standard), and the surface hardness of the quenched portion is 60 HRC or more. The outer side tapered roller 5 is also made of bearing steel subjected to the same quenching as the inner side tapered roller 5, but the inner side tapered roller 5 may be made of carburized steel as in the conventional example. .
[0014]
FIG. 3 shows an assembly process of the wheel bearing device 1. First, the assembly part 15 of the tapered roller 5 and the cage 6 is assembled in the single outer ring 4 (FIG. 3A) (FIG. 3B), and the seal 7 is assembled on the outer side thereof (FIG. 3C). ). The hub wheel 2 is assembled into the assembled parts (FIG. (D)), the inner ring 3 in one row is assembled into the hub wheel 2 (FIG. (E)), and the seal 7 is assembled on the inner side. (FIG. (F)) One end (inner side end) of the hub wheel 2 is crimped. Thus, the wheel bearing device 1 is completed as shown in FIG. 1 by forming the crimping portion 2c that presses the width surface of the inner ring 3 (FIG. 1G).
[0015]
According to the wheel bearing device of this configuration, as a characteristic of this type of bearing, the inner ring raceway surface 2b, that is, the raceway surface 2b of the inner ring 3, is subjected to a vehicle body weight and a turning lateral load on the raceway surface from the tire ground contact surface. The applied load factor becomes larger than the outer raceway surface 2b. However, since the inner ring 3 is made of bearing steel having a surface hardness of 60 HRC or more that has been subjected to quenching, the inner ring 3 having the inner ring raceway surface 2b of the inner row even for such a large load factor. The service life can be extended. Conventionally, bearing steel with a carburized layer has been used for the inner ring on the inner side, but in recent years, bearing steel that has been hardened by quenching has a fatigue life that is less than that of carburized steel due to the improvement of the refining method. It was found that a long life could be achieved even under severe surface pressure.
Further, since the tapered rollers 5 in the inner row are made of bearing steel having a surface hardness of 60 HRC or higher, which has been subjected to excessive quenching, as in the case of the inner ring 3, they are excellent in strength regardless of a large load factor. The tapered roller 5 is harder than the internal hardness (38 HRC or less) of the carburized steel, and is strong against internal cracks. For this reason, even when a large lateral load such as curb climbing is applied, internal cracks are prevented from occurring in the tapered rollers 5 in the inner side row.
Note that the rolling life of a bearing is influenced not only by hardness but also by the relationship with the residual compressive stress on the surface and the relationship with the amount of austenite. The lower the rolling life is, the shorter the rolling life is. For example, a steel material of the same material, which is 60 HRC with respect to 58 HRC, has data that can obtain a life of about 1.8 times.
[0016]
Further, since the hub wheel 2 is made of carbon steel, a hardened layer 20 having a surface hardness of 58 to 60 HRC is provided on a portion extending from the inner ring fitting surface 2a to the flange root portion 22a on the outer diameter surface portion of the hub wheel 2. The hardness of the flange 22 is improved, and the amount of deformation of the flange 22 when the vehicle turns is reduced. Therefore, the rigidity around the vehicle wheel is improved. Further, since the hardened layer 20 of the hub ring 2 is expanded to the inner ring fitting surface 2a, fretting wear occurring on the inner diameter surface of the inner ring 3 and the outer diameter surface of the hub ring 2 can be minimized. . Therefore, the occurrence of fretting wear does not cause rust, wear powder, galling or the like on the fitting surface between the inner ring 3 and the hub ring 2 and damage the inner ring 3, thereby improving the durability. .
[0017]
The outer ring 4 is also made of carbon steel, and since the hardened layer 21 having a surface hardness of 58 to 60 HRC is provided on the inner diameter side surface portion to be the outer ring raceway surfaces 4b and 4b of both rows, the long life of the outer ring 4 is achieved. Can also be realized.
[0018]
In addition, although the said embodiment demonstrated about the case where it applied to the wheel bearing apparatus 1 which supports a driving wheel, this invention is applicable also to the wheel bearing apparatus which supports a driven wheel.
[0019]
【The invention's effect】
In the wheel bearing device according to the present invention, the hub ring has an inner ring fitting surface on one end outer periphery for fitting the inner ring of one row of the double row tapered roller bearing, and another hub is adjacent to the inner ring fitting surface. It has a single-row inner ring raceway surface and a flange on the other end. A tapered roller held by a cage is interposed between the hub ring and the outer ring, and the hub ring is made of carbon steel. A hardened layer having a surface hardness of 58 to 60 HRC is provided in a portion extending from the inner ring fitting surface to the flange root portion in the surface portion of the hub wheel, and the single row of inner rings and tapered rollers are subjected to quenching with a surface hardness of 60 HRC or more. Because the bearing steel is made of, it is possible to extend the life of the inner ring on the inner side and ensure the strength of the tapered rollers in the inner row, improve the strength of the flange part of the hub wheel, reduce the amount of flange deformation when turning the vehicle, wheels The surrounding rigidity and strength can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a wheel bearing device according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a drive wheel support structure by the wheel bearing device.
FIG. 3 is a process explanatory diagram of an assembly process of the wheel bearing device.
FIG. 4 is a cross-sectional view of a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Wheel bearing apparatus 2 ... Hub ring 2a ... Inner ring fitting surface 2b ... Inner ring raceway surface 2c ... Clamping part 3 ... Inner ring 4 ... Outer ring 4b ... Outer ring raceway surface 5 ... Tapered roller 6 ... Cage 20 ... Hardened layer 21 ... Hardened layer 22 of outer ring ... Flange 22a of hub ring ... Flange root

Claims (3)

ハブ輪が、複列の円すいころ軸受の片列の内輪を嵌合させる内輪嵌合面を一端外周に有し、この内輪嵌合面に隣接して他の片列の内輪軌道面を有し、かつ他端にフランジを有し、このハブ輪と外輪との間に保持器に保持された円すいころを介在させ、上記ハブ輪を炭素鋼製とし、このハブ輪の表面部における上記内輪嵌合面からフランジ根元部にわたる部分に、表面硬さ５８〜６０ＨＲＣの硬化層を設け、上記片列の内輪および円すいころを、表面硬さ６０ＨＲＣ以上のずぶ焼き入れの施された軸受鋼としたことを特徴とする車輪用軸受装置。The hub ring has an inner ring fitting surface on one end outer periphery for fitting the inner ring of one row of double row tapered roller bearings, and has another inner row raceway surface adjacent to the inner ring fitting surface. And having a flange at the other end, and interposing a tapered roller held by a cage between the hub ring and the outer ring, the hub ring is made of carbon steel, and the inner ring fitting on the surface portion of the hub ring A hardened layer having a surface hardness of 58 to 60 HRC was provided in a portion extending from the mating surface to the flange root portion, and the inner ring and the tapered roller in the above-mentioned single row were made into bearing steel subjected to a quenching with a surface hardness of 60 HRC or more. A wheel bearing device characterized by the above. 請求項１において、上記外輪を炭素鋼製とし、この外輪の軌道面の部分に、表面硬さ５８〜６０ＨＲＣの硬化層を設けた車輪用軸受装置。The wheel bearing device according to claim 1, wherein the outer ring is made of carbon steel, and a hardened layer having a surface hardness of 58 to 60 HRC is provided on a portion of a raceway surface of the outer ring. 請求項１または請求項２において、上記ハブ輪の内輪嵌合面のさらに端部側に、上記片列の内輪の幅面を押し付けるフランジ状の加締部を有し、上記内輪嵌合面の上記硬化層を設ける範囲は、上記加締部の近傍までとした車輪用軸受装置。3. A flange-shaped crimping portion that presses the width surface of the inner ring of the single row on the further end side of the inner ring fitting surface of the hub wheel according to claim 1 or 2, A wheel bearing device in which the hardened layer is provided up to the vicinity of the caulking portion.
JP2002352724A 2002-12-04 2002-12-04 Bearing device for wheel Pending JP2004183815A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006076346A (en) * 2004-09-07 2006-03-23 Ntn Corp Bearing device for wheel
WO2007148436A1 (en) * 2006-06-21 2007-12-27 Ntn Corporation Bearing device for wheel
JP2008309270A (en) * 2007-06-15 2008-12-25 Ntn Corp Tapered roller bearing

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006076346A (en) * 2004-09-07 2006-03-23 Ntn Corp Bearing device for wheel
WO2007148436A1 (en) * 2006-06-21 2007-12-27 Ntn Corporation Bearing device for wheel
JP2008309270A (en) * 2007-06-15 2008-12-25 Ntn Corp Tapered roller bearing

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