JP2004045219A - Rolling bearing unit for wheel supporting with load-measuring device - Google Patents

Rolling bearing unit for wheel supporting with load-measuring device Download PDF

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JP2004045219A
JP2004045219A JP2002203072A JP2002203072A JP2004045219A JP 2004045219 A JP2004045219 A JP 2004045219A JP 2002203072 A JP2002203072 A JP 2002203072A JP 2002203072 A JP2002203072 A JP 2002203072A JP 2004045219 A JP2004045219 A JP 2004045219A
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load
rolling bearing
wheel
displacement
bearing unit
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JP3900031B2 (en
JP2004045219A5 (en
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Hiroo Ishikawa
石川　寛朗
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NSK Ltd
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NSK Ltd
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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
    • F16C41/00—Other accessories, e.g. devices integrated in the bearing not relating to the bearing function as such
    • F16C41/007—Encoders, e.g. parts with a plurality of alternating magnetic poles
    • 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
    • F16C33/72—Sealings
    • F16C33/723—Shaft end sealing means, e.g. cup-shaped caps or covers
    • 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
    • F16C33/72—Sealings
    • F16C33/76—Sealings of ball or roller bearings
    • 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
    • F16C19/02—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows
    • F16C19/14—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load
    • F16C19/18—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load with two or more rows of balls
    • F16C19/181—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load with two or more rows of balls with angular contact
    • F16C19/183—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load with two or more rows of balls with angular contact with two rows at opposite angles
    • F16C19/184—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load with two or more rows of balls with angular contact with two rows at opposite angles in O-arrangement
    • F16C19/185—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load with two or more rows of balls with angular contact with two rows at opposite angles in O-arrangement with two raceways provided integrally on a part other than a race ring, e.g. a shaft or housing
    • 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
    • F16C19/02—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows
    • F16C19/14—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load
    • F16C19/18—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load with two or more rows of balls
    • F16C19/181—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load with two or more rows of balls with angular contact
    • F16C19/183—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load with two or more rows of balls with angular contact with two rows at opposite angles
    • F16C19/184—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load with two or more rows of balls with angular contact with two rows at opposite angles in O-arrangement
    • F16C19/186—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load with two or more rows of balls with angular contact with two rows at opposite angles in O-arrangement with three raceways provided integrally on parts other than race rings, e.g. third generation hubs
    • 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
    • F16C2326/00—Articles relating to transporting
    • F16C2326/01—Parts of vehicles in general
    • F16C2326/02—Wheel hubs or castors

Abstract

<P>PROBLEM TO BE SOLVED: To realize a structure accurately and freely measuring the direction and the magnitude of load applied to on a hub 2 without increasing cost and weight. <P>SOLUTION: In the middle of the hub 2, an annular ring 29 to be detected which is provided with a cylinder part 30 and a bent part 31 are mounted. With displacement sensor units 26, 26 supported at 4 locations in the circumference of an outer wheel 1 and the ring 29 to be detected, the displacements in the radial direction and thrust direction of the hub 2 against the outer wheel are detected. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
この発明に係る荷重測定装置付車輪支持用転がり軸受ユニットは、車両（自動車）の車輪を懸架装置に対して回転自在に支持すると共に、この車輪に加わる力の方向及び大きさを測定して、車両の安定運行に寄与せしめるものである。
【０００２】
【従来の技術】
車両の車輪を懸架装置に対して回転自在に支持するのに、転がり軸受ユニットを使用する。又、アンチロックブレーキシステム（ＡＢＳ）やトラクションコントロールシステム（ＴＣＳ）を制御する為には、上記車輪の回転速度を検出する必要がある。この為、上記転がり軸受ユニットに回転速度検出装置を組み込んだ回転速度検出装置付転がり軸受ユニットにより、上記車輪を懸架装置に対して回転自在に支持すると共に、この車輪の回転速度を検出する事が、近年広く行なわれる様になっている。
【０００３】
図２５は、この様な目的で使用される従来構造の１例として、特開２００１−２１５７７号公報に記載された回転速度検出装置付の車輪支持用転がり軸受ユニットを示している。この回転速度検出装置付の車輪支持用転がり軸受ユニットは、懸架装置に支持された状態で使用時にも回転しない、請求項に記載した静止側軌道輪に相当する外輪１の内径側に、車輪を固定した状態で使用時に回転する、請求項に記載した回転側軌道輪に相当するハブ２を支持している。そして、このハブ２の一部に固定したセンサロータ３の回転速度を、上記外輪１に固定したカバー４に支持した回転速度検出センサ５により検出自在としている。図示の例では、この回転速度検出センサ５として、上記センサロータ３と全周に亙って対向する、円環状のものを使用している。又、上記ハブ２を回転自在に支持する為に、上記外輪１の内周面に、それぞれが請求項に記載した静止側軌道に相当する複列の外輪軌道６、６を設けている。又、上記ハブ２の外周面、及びこのハブ２に外嵌しナット７によりこのハブ２に対し結合固定した状態で上記ハブ２と共に上記回転側軌道輪を構成する内輪８の外周面に、それぞれが請求項に記載した回転側軌道に相当する内輪軌道９、９を設けている。そして、これら各内輪軌道９、９と上記各外輪軌道６、６との間にそれぞれ複数個ずつの転動体１０、１０を、それぞれ保持器１１、１１により保持した状態で転動自在に設け、上記外輪１の内側に上記ハブ２及び内輪８を、回転自在に支持している。
【０００４】
又、上記ハブ２の外端部（車両への組み付け状態で幅方向外側となる端部を言い、図２５の左端部）で上記外輪１の外端部から軸方向外方に突出した部分に、車輪を取り付ける為のフランジ１２を設けている。又、上記外輪１の内端部（車両への組み付け状態で幅方向中央側となる端部を言い、図２５の右端部）に、この外輪１を懸架装置に取り付ける為の取付部１３を設けている。又、上記外輪１の外端開口部と上記ハブ２の中間部外周面との間の隙間は、シールリング１４により塞いでいる。尚、重量の嵩む車両用の転がり軸受ユニットの場合には、上記複数個の転動体１０、１０として、図示の様な玉に代えて、テーパころを使用する場合もある。
【０００５】
上述の様な転がり軸受ユニットに回転速度検出装置を組み込むべく、上記内輪８の内端部で上記内輪軌道９から外れた部分の外周面には、前記センサロータ３を外嵌固定している。このセンサロータ３は、軟鋼板等の磁性金属板に塑性加工を施す事により、全体を円環状に形成したもので、互いに同心の被検出用円筒部１５と支持用円筒部１６とを備え、このうちの支持用円筒部１６を上記内輪８の内端部に締まり嵌めで外嵌する事により、この内輪８の内端部に固定している。
又、上記被検出用円筒部１５には、それぞれがこの被検出用円筒部１５の軸方向に長いスリット状の透孔１７、１７を多数、円周方向に関して等間隔で形成する事により、上記被検出用円筒部１５の磁気特性を、円周方向に亙って交互に且つ等間隔に変化させている。
【０００６】
更に、上記外輪１の内端開口部には前記カバー４を、上記センサロータ３の被検出用円筒部１５を覆う状態で嵌合固定して、上記外輪１の内端開口部を塞いでいる。金属板を塑性加工して成る、上記カバー４は、上記外輪１の内端開口部に内嵌固定自在な嵌合筒部１８と、この内端開口部を塞ぐ塞ぎ板部１９とを有する。そして、この塞ぎ板部１９内に、前記回転速度検出センサ５を保持固定している。又、この塞ぎ板部１９の外周寄り部分には通孔２０を形成し、この通孔２０を通じて上記回転速度検出センサ５の出力を取り出す為のコネクタ２１を、上記カバー４外に取り出している。この様に回転速度検出センサ５をカバー４内に保持固定した状態で、この回転速度検出センサ５の外周面に設けた検知部は、上記センサロータ３を構成する被検出用円筒部１５の内周面に、微小隙間を介して対向する。
【０００７】
上述の様な回転速度検出装置付の車輪支持用転がり軸受ユニットの使用時には、上記外輪１の外周面に固設した取付部１３を懸架装置に対して、図示しないボルトにより結合固定すると共に、前記ハブ２の外周面に固設したフランジ１２に図示しない車輪を、このフランジ１２に設けたスタッド２２により固定する事で、上記懸架装置に対して上記車輪を回転自在に支持する。この状態で車輪が回転すると、上記回転速度検出センサ５の検知部の端面近傍を、上記被検出用円筒部１５に形成した透孔１７、１７と、円周方向に隣り合う透孔１７、１７同士の間に存在する柱部とが交互に通過する。この結果、上記回転速度検出センサ５内を流れる磁束の密度が変化し、この回転速度検出センサ５の出力が変化する。この様にして回転速度検出センサ５の出力が変化する周波数は、上記車輪の回転数に比例する。従って、上記回転速度検出センサ５の出力を図示しない制御器に送れば、ＡＢＳやＴＣＳを適切に制御できる。
【０００８】
即ち、上記回転速度検出センサ５の出力と、別途車体側に設けた加速度センサの出力とを比較して、これら両センサの出力に整合性がない場合に、タイヤの外周面と路面との当接部に滑りが発生していると判断して、上記ＡＢＳやＴＣＳを制御する。即ち、制動時に上記加速度センサが検出する車両の減速度に比べて回転速度検出センサ５の出力に基づいて求められる車輪の減速度が大きい場合には、上記滑りが発生していると判断して、ブレーキ装置のホイルシリンダ部分の油圧を制御し、車両が停止する以前に車輪の回転が止まる事を防止して、車両の走行姿勢の安定性確保を図る。又、加速時には、上記回転速度検出センサ５の出力に基づいて求められる車輪の加速度に比べて、上記加速度センサにより求められる車両の加速度が小さい場合（或は、従動輪の加速度に比べて駆動輪の加速度が大きい場合）には、上記滑りが発生していると判断して、上記車輪に制動を加えたり、或はエンジンの出力を絞る（低下させる）事により、タイヤの外周面と路面との滑りを防止して、車両の走行姿勢の安定化を図る。
【０００９】
上述した様な従来から広く知られている回転速度検出装置付の車輪支持用転がり軸受ユニットによれば、制動時や加速時に於ける車両の走行姿勢の安定性確保を図れるが、より厳しい条件でもこの安定性の確保を図る為には、車両の走行安定性に影響するより多くの情報を取り入れて、ブレーキやエンジンの制御を行なう事が必要になる。これに対して、従来の回転速度検出装置付転がり軸受ユニットを利用したＡＢＳやＴＣＳの場合には、タイヤと路面との滑りを検知してブレーキやエンジンを制御する、所謂フィードバック制御を行なっている。この為、これらブレーキやエンジンの制御が一瞬とは言え遅れる為、厳しい条件下での性能向上の面からは改良が望まれる。即ち、従来構造の場合には、所謂フィードフォワード制御により、タイヤと路面との間に滑りが発生しない様にしたり、左右の車輪の制動力が極端に異なる所謂ブレーキの片効きを防止する事はできない。更には、トラック等で、積載状態が不良である事に基づいて走行安定性が不良になるのを防止する事もできない。
【００１０】
この様な事情に鑑みて、前記特開２００１−２１５７７号公報には、図２６に示す様な、転がり軸受ユニットに加わる荷重を測定自在とした構造が記載されている。この従来構造の第２例の場合には、外輪１の軸方向中間部で１対の外輪軌道６、６同士の間部分に、この外輪１を直径方向に貫通する取付孔２３を、この外輪１の上端部にほぼ鉛直方向に形成している。そして、この取付孔２３内に、円杆状（棒状）の変位センサ２４を装着している。この変位センサ２４の先端面（下端面）に設けた検出面は、ハブ２の軸方向中間部に外嵌固定したセンサリング２５の外周面に近接対向させている。そして、上記変位センサ２４は、上記検出面と上記センサリング２５の外周面との距離が変化した場合に、その変化量に対応した信号を出力する。
【００１１】
上述の様に構成する従来構造の第２例の場合には、上記変位センサ２４の検出信号に基づいて、この変位センサ２４を組み込んだ車輪支持用転がり軸受ユニットに加わる荷重を求める事ができる。即ち、車両の懸架装置に支持した上記外輪１は、この車両の重量により下方に押されるのに対して、車輪を支持固定したハブ２は、そのままの位置に止まろうとする。この為、上記重量が嵩む程、上記外輪１やハブ２、並びに転動体１０、１０の弾性変形に基づいて、これら外輪１の中心とハブ２の中心とのずれが大きくなる。そして、この外輪１の上端部に設けた、上記変位センサ２４の検出面と上記センサリング２５の外周面との距離は、上記重量が嵩む程短くなる。そこで、上記変位センサ２４の検出信号を制御器に送れば、予め実験等により求めた関係式等から、当該変位センサ２４を組み込んだ車輪支持用転がり軸受ユニットに加わる荷重を求める事ができる。この様にして求めた、各車輪支持用転がり軸受ユニットに加わる荷重に基づいて、ＡＢＳを適正に制御する他、積載状態の不良を運転者に知らせる。
【００１２】
図２６に示した従来構造の第２例の場合、車両の重量に基づいて鉛直方向に加わる荷重を測定できるが、例えば旋回走行時に遠心力等に基づいて加わるモーメント荷重を測定する事はできない。この為、車両のあらゆる走行状態に応じて、安定走行の為に適切な制御を行なう為の信号を得る面からは改良が望まれる。この様な場合に使用可能な構造として、特開平１０−７３５０１号公報に記載された構造が知られている。この公報に記載された構造によれば、上記モーメント荷重を含め、車両の走行時に車輪に加わる各方向の荷重を測定できる。
【００１３】
【発明が解決しようとする課題】
上述した特開平１０−７３５０１号公報に記載された従来構造は、荷重測定の為に付加する部材が多く、しかも大型の部材を含む為、コスト並びに重量が嵩む事が避けられない。荷重測定装置を組み付ける部分は、懸架装置を構成するばねよりも車輪側であり、この荷重測定装置の構成部材は所謂ばね下荷重になり、少しの重量も乗り心地を中心とする走行性能の悪化に結び付く為、改良が望まれている。
【００１４】
又、近年ＡＢＳやＴＣＳ、更には、エンジンの出力とブレーキとを制御する事により車両の横方向の安定性を確保するビークルスタビリティーコントロールシステム（ＶＳＣ）等を高度且つ適正に制御すべく、上記荷重測定装置の測定値と共に、車両の速度等も、より高精度に測定する事が求められている。しかも、この様な高精度化と共に、上記荷重測定装置や車両速度測定装置の低廉化も求められている。
本発明の荷重測定装置付車輪支持用転がり軸受ユニットは、この様な事情に鑑みて発明したものである。
【００１５】
【課題を解決するための手段】
本発明の荷重測定装置付車輪支持用転がり軸受ユニットは、車輪支持用転がり軸受ユニットと荷重測定装置とを備える。
このうちの車輪支持用転がり軸受ユニットは、使用状態で懸架装置に支持固定される静止側軌道輪と、使用状態で車輪を支持固定する回転側軌道輪と、これら静止側軌道輪と回転側軌道輪との互いに対向する周面に存在する静止側軌道と回転側軌道との間に設けられた複数個の転動体とを備えたものである。
又、上記荷重測定装置は、上記回転側軌道輪の回転中心と同心に設けられた円筒状のラジアル被検出面及びこの回転側軌道輪の回転中心に対し直角方向に設けられたスラスト被検出面と、上記静止側軌道輪に設けられた少なくとも１個の変位センサユニットとから成るものである。
そして、この変位センサユニットは、ラジアル検出部とスラスト検出部とを備え、このうちのラジアル検出部と上記ラジアル被検出面との距離、並びにスラスト検出部と上記スラスト被検出面との距離を測定自在なものとしている。
更には、上記変位センサユニットから測定される上記各距離と、予め求めた上記車輪支持用転がり軸受ユニットに付与された予圧の値とから、上記回転側軌道輪に加わる荷重を求める。
【００１６】
【作用】
上述の様に構成する本発明の荷重測定装置付車輪支持用転がり軸受ユニットによれば、回転側軌道輪のラジアル方向の変位だけでなくスラスト方向の変位も測定できる。そして、変位センサユニットが検出するこれら各方向の変位に基づいて、車輪支持用転がり軸受ユニットに加わる、各方向の荷重を求める事ができる。しかも、これら各方向に加わる荷重を、車輪支持用転がり軸受ユニットに付与された予圧の値を考慮しつつ求める為、この車輪支持用転がり軸受ユニットに加わる各方向の荷重を高精度に求める事ができ、ＡＢＳやＴＣＳ、ＶＳＣ等の制御を高度且つ適正に行なえる。
【００１７】
【発明の実施の形態】
図１〜４は、本発明の実施の形態の第１例を示している。尚、本例の特徴は、ハブ２に固定した車輪（図示省略）に加わる荷重の方向及び大きさを求めて、ＡＢＳやＴＣＳ、ＶＳＣ等を適正に制御できる構造を得る点にある。この為に本例の場合には、上記ハブ２に加わる荷重だけでなく、このハブ２の回転速度を検出自在としている。但し、この回転速度を検出する部分の構造及び作用に就いては、前述の図２５〜２６に示した従来構造と同様であるから、同等部分には同一符号を付して重複する説明は省略し、以下、本発明の特徴部分を中心に説明する。
【００１８】
本例の場合には、複列の外輪軌道６、６の間に位置する、外輪１の軸方向中間部分の、円周方向等間隔４個所位置に取付孔２３ａ、２３ａを、それぞれ上記外輪１の内外両周面同士を連通させる状態で形成している。本例の場合、上記４個の取付孔２３ａ、２３ａのうちの２個の取付孔２３ａ、２３ａを鉛直方向に、残り２個の取付孔２３ａ、２３ａを水平方向に、それぞれ形成している。そして、これら各取付孔２３ａ、２３ａ内に、それぞれ変位センサユニット２６、２６を挿入している。
【００１９】
これら各変位センサユニット２６、２６はそれぞれ、上記ハブ２のラジアル方向（径方向）の変位及びスラスト方向（軸方向）の変位を測定自在とするもので、それぞれが非接触式である、２個の変位測定素子２７ａ、２７ｂを有する。即ち、静電容量型の近接センサの如き、非接触式で微小変位量を測定自在な上記各変位測定素子２７ａ、２７ｂを、上記各変位センサユニット２６、２６を構成する合成樹脂製のホルダ２８の先端面部分と先端部側面部分とに包埋支持している。上記各変位測定素子２７ａ、２７ｂのうち、上記ホルダ２８の先端面部分に包埋支持された変位測定素子２７ａがラジアル検出部を構成し、先端部側面部分に包埋支持した変位測定素子２７ｂがスラスト検出部を構成する。
【００２０】
一方、複列の内輪軌道９、９の間に位置する、上記ハブ２の中間部に、被検出リング２９を外嵌固定している。この被検出リング２９は、金属板にプレス加工等の塑性加工を施す事により、断面Ｌ字形で全体を円環状としたもので、円筒部３０と、この円筒部３０の軸方向一端部（図１、３の右端部）から径方向外方に直角に折れ曲がった折れ曲がり部３１とを備える。本例の場合、上記円筒部３０の外周面をラジアル被検出面とし、上記折れ曲がり部３１の片側面（図１、３の左側面）をスラスト被検出面としている。
【００２１】
この様な被検出リング２９に対して上記各変位センサユニット２６、２６の変位側測定素子２７ａ、２７ｂの検出部を、それぞれ近接対向させている。即ち、上記ラジアル検出部を構成する変位測定素子２７ａを、上記ラジアル被検出面である上記円筒部３０の外周面に近接対向させている。そして、上記変位測定素子２７ａにより、前記外輪１に対する上記ハブ２のラジアル方向（径方向）の変位を測定自在としている。又、上記スラスト検出部を構成する変位測定素子２７ｂを、上記スラスト被検出面である折れ曲がり部３１の片側面に近接対向させている。そして、上記変位測定素子２７ｂにより、上記外輪１に対する上記ハブ２のスラスト方向（軸方向）の変位を測定自在としている。
【００２２】
本例の荷重測定装置付車輪支持用転がり軸受ユニットの場合には、前述の様に上記４個の変位センサユニット２６、２６により、円周方向４個所位置に於いて、上記外輪１に対する上記ハブ２の、ラジアル方向及びスラスト方向の変位を測定する様に構成している。上記各変位センサユニット２６、２６が測定した、これら各変位センサユニット２６、２６毎に２種類ずつ合計８種類の検出信号は、それぞれハーネス３２、３２により取り出して、図示しない制御器に入力している。そして、この制御器が、上記各変位センサユニット２６、２６から送り込まれる検出信号に基づき、車輪支持用転がり軸受ユニットに加わる、各方向の荷重を求める。
【００２３】
例えば、上記各車輪支持用転がり軸受ユニットに、車重等に基づく鉛直方向（下向き）の荷重が加わった場合には、鉛直方向に存在する２個の変位センサユニット２６、２６のうち、上側の変位センサユニット２６で、上記ラジアル検出部を構成する変位測定出素子２７ａと、上記ラジアル被検出面である上記円筒部３０の外周面との距離が狭まり、下側の変位センサユニット２６でこの距離が広がる。この際の距離の変化量は、上記荷重が大きくなる程大きくなる。水平方向（前後方向）に存在する２個の変位センサユニット２６、２６に関しては、この距離は変化しない。
【００２４】
これに対して、何らかの原因で（例えば加速や制動に伴って）前記ハブ２に水平方向の荷重が加わった場合には、水平方向に存在する２個の変位センサユニット２６、２６のうち、荷重の作用方向前側の変位センサユニット２６で、上記ラジアル検出部を構成する変位測定素子２７ａと、上記ラジアル被検出面である上記円筒部３０の外周面との距離が縮まり、同じく作用方向後側の変位センサユニット２６でこの距離が広がる。この際の距離の変化量も、上記荷重が大きくなる程大きくなる。鉛直方向に存在する２個の変位センサユニット２６、２６に関しては、この距離は変化しない。斜め方向の荷重によっては、総てのセンサユニット２６、２６に関して、上記距離が変化する。
【００２５】
従って、円周方向に関して等間隔に配置された４個の変位センサユニット２６、２６のラジアル検出部を構成する変位測定素子２７ａ、２７ａの検出信号を比較すれば、ラジアル荷重の作用する方向とその大きさとを知る事ができる。尚、上記各部の距離の変化量とラジアル荷重の大きさ及び作用方向は、予め計算式や多数の実験、或はコンピュータ解析により求めておく。特に、特に本例の場合には、後述する様に、車輪支持用転がり軸受ユニットに付与された予圧の値を考慮して、上記各部の距離の変化量とラジアル荷重の大きさ及び作用方向との関係を求めておく。
【００２６】
次に、旋回走行等により前記ハブ２に鉛直方向のモーメント荷重、即ち、図５にＭｘで示す方向のモーメント荷重Ｍｘが加わり、上記ハブ２の中心軸と前記外輪１の中心軸とが（鉛直方向に）不一致になった場合に就いて説明する。この場合には、上記各変位センサユニット２６、２６のスラスト検出部を構成する、前記変位測定素子２７ｂ、２７ｂの検出信号に基づいて、上記モーメント荷重Ｍｘの方向及びその大きさを求める。例えば、旋回時に（旋回円の径方向に関して）外側の車輪を支持したハブ２には、遠心力により大きなモーメント荷重Ｍｘが、図４の時計方向に加わる。この結果、同図に誇張して示す様に、上記ハブ２の中心軸αが、上記外輪１の中心軸βに対し傾斜する。
【００２７】
この状態では、鉛直方向に配置された１対の変位センサユニット２６、２６のうち、一方の変位センサユニット２６に関するスラスト検出部とスラスト被検出面との距離が縮まり、他方の変位センサユニット２６に関するスラスト検出部とスラスト被検出面との距離が広がる。例えば図４に示した例の場合には、上側の変位センサユニット２６のスラスト検出部を構成する変位測定素子２７ｂと、スラスト被検出面である前記折れ曲がり部３１の片側面との距離が広がる。これに対して、下側の変位センサユニット２６の変位測定素子２７ｂと上記折れ曲がり部３１の片側面との距離は縮まる。この場合に、これら各変位測定素子２７ｂ、２７ｂと折れ曲がり部３１の片側面との距離が変化する量は、上記モーメント荷重Ｍｘが大きくなる程大きくなる。
【００２８】
又、モーメント荷重が水平方向に加わった場合、即ち、図５にＭｚで示す方向のモーメント荷重Ｍｚが加わり、上記ハブ２の中心軸と前記外輪１の中心軸とが（水平方向）に不一致になった場合には、水平方向に配置した２個の変位センサユニット２６、２６のスラスト検出部を構成する変位測定素子２７ｂ、２７ｂと、スラスト被検出面である上記折れ曲がり部３１の片側面との距離が変化する。
更に、モーメント荷重が斜め方向に加わった場合には、総て（４個）の変位センサユニット２６、２６のスラスト検出部を構成する変位測定素子２７ｂ、２７ｂと、スラスト被検出面である上記折れ曲がり部３１の片側面との距離が変化する。
【００２９】
従って、円周方向に関して等間隔に配置された４個の変位センサユニット２６、２６のスラスト検出部を構成する上記各変位測定素子２７ｂ、２７ｂの検出信号（必要に応じてラジアル検出部を構成する変位測定素子２７ａ、２７ａ）を比較すれば、モーメント荷重の作用する方向とその大きさとを知る事ができる。尚、上記各部の距離の変化量とモーメント荷重の大きさとの関係、更には各変位センサユニット２６、２６の検出信号の差とモーメント荷重の作用方向との関係に関しても、予め計算式や多数の実験、或はコンピュータ解析により求めておく。
この場合にも、車輪支持用転がり軸受ユニットに付与された予圧の値を考慮して、上記各部の距離の変化量とモーメント荷重の大きさ及び作用方向との関係を求めておく。
【００３０】
更に、何らかの原因で前記ハブ２にスラスト荷重が加わった場合には、総ての変位センサユニット２６、２６に関して、スラスト検出部を構成する上記各変位測定素子２７ｂ、２７ｂと、スラスト被検出面である上記折れ曲がり部３１の片側面との距離が変化する。そして、この変化の方向（広がるか縮まるか）により上記スラスト荷重の方向が分かり、変化量でその大きさが分かる。
【００３１】
尚、実際の走行時には、上記ハブ２に対して純ラジアル荷重、純モーメント荷重、或は純スラスト荷重が加わる事は稀であり、これら各荷重が混ざり合った状態、即ち、図５に示す様に各荷重Ｆｘ、Ｆｙ、Ｆｚ、Ｍｘ、Ｍｙ、Ｍｚが混ざり合った状態で、タイヤ３３及び車輪３４を介して上記ハブ２に加わる。従って前記制御器は、上記各変位センサユニット２６、２６の各変位測定素子２７ａ、２７ｂから送り込まれる、合計８種類の検出信号に基づいて、上記ハブ２に加わる荷重の種類、方向、大きさを求める。この様に、８種類の検出信号から荷重の種類、方向、大きさを求めるプログラムは、予め計算式や多数の実験、或はコンピュータシミュレーションにより決定して、上記制御器を構成するマイクロコンピュータ中にインストールしておく。
【００３２】
尚、ラジアル方向の変位検出精度を向上させる為には、上記ラジアル検出部を構成する変位測定素子２７ａの測定部の中心を次の様に規制する事が好ましい。
即ち、前記ハブ２にモーメント荷重が加わった場合に、このハブ２の揺動変位の中心となる点Ｏでこのハブ２の中心軸に直交する仮想平面Ｘ上、又はこの仮想平面Ｘを基準として軸方向に関するずれが１〜２ｍｍ以内の部分に、上記測定部を位置させる。この理由は、上記ラジアル検出部の検出値に、上記モーメント荷重に基づく変位が影響しにくくして、各方向の荷重を求め易くする為である。但し、上記変位測定素子２７ａの測定部の中心が上記仮想平面Ｘから２ｍｍ以上ずれても、制御器にインストールするソフトウェアにより変位量を計算する事は可能であるから、上記変位測定素子２７ａの測定部の中心位置は適宜決定できる。又、スラスト方向の検出精度を向上させる為には、スラスト被検出部を構成する上記折れ曲がり部３１の片側面を、上記仮想平面Ｘ上、又はこの仮想平面Ｘを基準として軸方向に関するずれが１〜２ｍｍ以内の部分に位置させる事が好ましい。
【００３３】
又、上記各変位センサユニット２６、２６の各変位測定素子２７ａ、２７ｂで測定される上記各距離と、上記車輪支持用転がり軸受ユニットを構成する上記ハブ２に加わる各方向の荷重との関係は、この転がり軸受ユニットに付与される予圧の値によって異なってくる。具体的には、この予圧の値が大きいと、上記車輪支持用転がり軸受ユニットの剛性が増大する結果、上記ハブ２に加わる各方向の荷重に対して、上記各変位測定素子２７ａ、２７ｂで測定される上記各距離が小さくなる傾向となる。一方、上記予圧の値が小さいと、上記車輪支持用転がり軸受ユニットの剛性が低下する結果、上記ハブ２に加わる各方向の荷重に対して、上記各変位測定素子２７ａ、２７ｂで測定される上記各距離が大きくなる傾向となる。
【００３４】
この為、本例の場合には、上記ハブ２に加わる各方向の荷重Ｆｘ、Ｆｙ、Ｆｚ、Ｍｘ、Ｍｙ、Ｍｚ（図５）を、上記各変位測定素子２７ａ、２７ｂで測定される上記各距離だけでなく、予め求めた上記車輪支持用転がり軸受ユニットに付与された予圧の値も考慮して（予圧の値に応じ補正して）求める様にしている。即ち、上述の様に本例の場合には、上記ハブ２に加わる荷重の種類、方向、大きさを求める為の上記制御器に組み込むプログラムを、予め求めた計算式や多数の実験、或はコンピュータシミュレーションにより決定する。
【００３５】
そこで、この様にプログラムを決定する際に、上記車輪支持用転がり軸受ユニットに付与される予圧の値毎に、上記ハブ２に加わる荷重の種類、方向、大きさと、上記各変位測定素子２７ａ、２７ｂで測定される上記各距離との関係を、同じく計算式や多数の実験、或はコンピュータシミュレーション等により求め、上記プログラムに反映させる。又、これと共に、上記制御器を構成するメモリに、当該車輪支持用転がり軸受ユニットの予圧の値を、上記荷重を求める際の補正データとして入力自在（記憶自在）とする。そして、運転時に上記各変位測定素子２７ａ、２７ｂで測定される上記各距離から上記荷重を、上記制御器に入力した予圧の値に応じて補正した状態で測定自在とする。尚、上記各変位測定素子２７ａ、２７ｂに対する前記被検出リング２９の変位誤差を補正すべく、この被検出リング２９を取り付けたハブ２を１回転又は複数回回転させ、上記各変位測定素子２７ａ、２７ｂと被検出リング２９との変位誤差を上記メモリに記憶させる事も好ましい。上記被検出リング２９を複数回回転させて上記変位誤差を求める場合には、平均値を上記メモリに記憶させる。
【００３６】
又、上記車輪支持用転がり軸受ユニットに付与された予圧の値は、従来から知られている各種方法により求める。例えば、この車輪支持用転がり軸受ユニットの回転トルクを測定する事や、固有振動数を測定する事、或は、前記内輪８を軸方向に変位不能に固定する為のナット７の締め付け量を規制する事等により、予圧の値を求める（知る）。そして、この様に求めた予圧の値を、上記車輪支持用転がり軸受ユニットの製造工場や自動車組立工場で、上記制御器のメモリに入力する。尚、上記車輪支持用転がり軸受ユニットの予圧の値をこの転がり軸受ユニットの製造工場で測定し、上記自動車組立工場等で上記制御器に入力する場合には、上記製造工場で予圧の値をバーコード化して、上記各転がり軸受ユニットにその値を添付しておく。この様に予圧の値をバーコード化して添付しておけば、上記自動車組立工場等でこの値（予圧データ）の入力を容易に行なえる。
【００３７】
又、上記車輪支持用転がり軸受ユニットに付与された予圧の値を、上記自動車組立工場で求める事もできる。即ち、上記車輪支持用転がり軸受ユニットを自動車に組み付けた状態で、この転がり軸受ユニットの予圧を測定しても良い。具体的には、この車輪支持用転がり軸受ユニットを自動車に組み付けた状態で、この転がり軸受ユニットを構成する前記ハブ２に軸方向の荷重を加え、この荷重の値とこのハブ２の（軸方向）変位量との関係から上記転がり軸受ユニットに付与された予圧の値を求めても良い。この様に予圧の値を求める場合には、自動車の車体を浮かせて上記車輪支持用転がり軸受ユニットに車重（車体の重量）が加わらない状態で求める事も可能であるし、上記車体を浮かせずに上記転がり軸受ユニットに車重が加わった状態で、この車重を考慮して求める事も可能である。
【００３８】
尚、以上の説明は、車輪支持用転がり軸受ユニットに加わる各方向の荷重の作用方向と大きさとを求める為、円周方向等間隔４個所位置に変位センサユニット２６、２６を設置した場合に就いて示した。上記荷重の作用方向と大きさとを高精度で求める為には、上述の様に４個の変位センサユニット２６、２６を設ける事が最も好ましい。但し、これら各変位センサユニット２６、２６の数を少なくする事により、部品点数の低減等に基づくコスト低減を図る事もできる。例えば、図６に示す実施の形態の第２例の様に、上端（或は下端）位置と水平方向片側位置との様に、円周方向に関する位相が９０度ずれた２個所位置に変位センサユニット２６、２６を設けた場合でも、上記荷重の作用方向と大きさとを求める事は可能である。更に、図７に示す実施の形態の第３例の様に、鉛直方向（或は水平方向）から４５度ずれた１個所位置に変位センサユニット２６を設けた場合でも、上記荷重の作用方向と大きさとを求める事は可能である。
【００３９】
尚、モーメント荷重が加わった場合に、ラジアル方向の変位とスラスト方向の変位とを独立して検出できない為、変位センサユニットのラジアル検出部の検出信号とスラスト検出部の検出信号との処理が多少面倒になるが、図８〜１０に示す様な構造を採用すれば、転がり軸受ユニットへの変位センサユニットの取付作業を容易にできる。即ち、この図８〜１０に示す、本発明の実施の形態の第４例の構造の場合には、ハブ２の中間部に、回転速度検出の為のセンサロータ３ａを外嵌固定している。そして、外輪１の軸方向中間部で円周方向１個所位置に形成した取付孔２３ｂに、回転速度センサ５ａを挿入し、この回転速度検出センサ５ａの検出面を、上記センサロータ３ａの外周面に近接対向させている。
【００４０】
一方、上記ハブ２の内端部に外嵌固定した内輪８の内端部に、上記ラジアル方向及びスラスト方向の変位を検出する為の被検出リング２９ａの基端部（図８〜９の左端部）を外嵌固定している。この被検出リング２９ａの形状は前述の図１に示した実施の形態の第１例に組み込んだセンサロータ３と同様であるが、透孔１７は設けていない。又、上記外輪１の内端開口部を塞いだカバー４に、変位センサユニット２６ａを保持固定している。そして、この変位センサユニット２６ａの円周方向４個所位置にそれぞれ支持した変位測定素子２７ａ、２７ｂの検出面を、上記被検出リング２９ａの内周面或は内側面に、ラジアル方向或はスラスト方向に近接対向させている。
【００４１】
上述の様な本例の構造の場合には、上記外輪１に設ける取付孔２３ｂが１個で済む為、この取付孔２３ｂの形成作業が容易になってコスト低減を図れる他、上記外輪１の肉厚を特に大きくしなくても、この外輪１の強度確保を図れる。又、各方向の荷重によって上記外輪１と上記ハブ２とが変位した場合には、上記各変位測定素子２７ａ、２７ｂと上記被検出リング２９ａの内周面或は内側面との距離が変化するので、この変化の大きさと変化の方向とにより、上記荷重の方向と大きさとを求める事ができる。
【００４２】
尚、上述した実施の形態の各例で、ラジアル方向或はスラスト方向の変位を検出する為の変位測定素子２７ａ、２７ｂは、従来から知られている各種構造のものを使用できる。例えば、図１１に示す様な磁気誘導式のもの、或は、図１２に示す様な渦電流式のものが、好ましく利用できる。このうち、図１１に示した磁気誘導式のものを使用する場合には、被検出リング２９、２９ａの材質は、鋼等の磁性材とする。そして、鉄芯３５に巻回した第一のコイル３６に励磁電流を流す事により、この鉄芯３５に巻回した第二のコイル３７に、この鉄芯３５と上記被検出リング２９、２９ａとの距離に応じた測定値信号を流す。又、図１２に示した渦電流式のものを使用する場合には、被検出リング２９、２９ａの材質として鋼等の磁性材でも良いが、好ましくは、アルミニウム、銅、黄銅、亜鉛等の、非磁性金属とする。そして、フェライト芯３８に巻回したコイル３９に励磁電流を流し、このフェライト芯３８と上記被検出リング２９、２９ａとの距離に応じて変化する上記コイル３９のインピーダンスを検出する。
【００４３】
尚、この様にコイル３９のインピーダンスを検出する為に、このインピーダンスの変化を電圧又は周波数変化に変換する。この様な電圧又は周波数変化に変換する方法として、発振法や同調法、ブリッジ法、正帰還法が知られている。例えばこのうちのブリッジ法は、図１３に示す様に、検出コイルである上記コイル３９と、基準コイル４０と、抵抗４１、４１と水晶発振器４２とによりブリッジ回路４３を構成し、このブリッジ回路４３の不平衡電圧を計測する事により、上記距離に応じて変化する上記インピーダンスの変化を検出する。又、この様な渦電流式のものを使用する場合、上述の様に被検出リング２９、２９ａの材質を、アルミニウム、銅、黄銅、亜鉛等の、非磁性金属とする他、鋼等の磁性材も使用可能である。要は、所望の性能やコスト等に応じて最適のものを選択する。
【００４４】
又、上述の様な渦電流式の場合、例えば４００００回／Ｓでサンプリングを行なえ、且つ、０．４μｍの分解能を有し、測定可能距離が０〜２ｍｍ程度のものが、一般に市販されている。本発明の場合、ラジアル方向或はスラスト方向の変位を図る為の変位測定素子２７ａ、２７ｂと被検出リング２９、２９ａとの距離を、０．５、〜１．５ｍｍ程度とする為、上記市販されているものをそのまま使用できる。
【００４５】
又、軸方向に隣り合う上記変位測定素子２７ａ、２７ｂにこの様な渦電流式のものを使用する場合、これら各変位測定素子２７ａ、２７ｂ同士が互いの渦電流の影響を受ける事により、測定誤差が生じる可能性がある。この様な渦電流の影響を避ける為に、図１４に示す様に、被検出リング２９ａの一部で上記各変位測定素子２７ａ、２７ｂと近接対向する部分の間部分、即ち、この被検出リング２９ａのラジアル被検出面とスラスト被検出面との間部分に、全周に亙り絶縁材４４を設ける。そして、これら被検出面同士を絶縁する事により、上記各変位測定素子２７ａ、２７ｂ同士が互いの渦電流の影響を受ける事を防止する。
【００４６】
尚、この様な渦電流の影響を防止する為に、上記各変位測定素子２７ａ、２７ｂに流れる電流をスイッチングにより切り換えて測定しても良い。即ち、軸方向に隣り合う上記変位測定素子２７ａ、２７ｂのうちの何れか一方の変位測定素子２７ａ（２７ｂ）が測定を行なう際は、他方の変位測定素子２７ｂ（２７ａ）が測定を行なわない様に（渦電流が発生しない様に）、これら各変位測定素子２７ａ（２７ｂ）を流れる電流を交互に切り換えて使用しても良い。更には、円周方向４個所位置にそれぞれ設けられた上記各変位測定素子２７ａ、２７ｂ同士が、上下左右各方向に生じる渦電流による影響を受ける事を防止すべく、それぞれの位置の変位測定素子２７ａ、２７ｂ毎にスイッチングを行ない、これら各変位測定素子２７ａ、２７ｂを流れる電流を交互に切り換えて測定しても良い。
【００４７】
又、上記被検出リング２９ａに惹起される渦電流が、この被検出リング２９ａを固定した内輪８に、この被検出リング２９ａを通じて放出（電播）するのを防止する為に、この被検出リング２９ａを前記非磁性金属とすると共に、上記内輪８を磁性金属である鋼製としたり、或は、この内輪８に上記被検出リング２９ａを、絶縁材４４ａを介して固定したりしても良い。更には、上記内輪８や上記被検出リング２９ａの表面に、絶縁処理を施しても良い。
【００４８】
又、前述の図５に示す様に、車輪支持用転がり軸受ユニットを構成するハブ２（図１、８）には、各荷重Ｆｘ、Ｆｙ、Ｆｚ、Ｍｘ、Ｍｙ、Ｍｚが混ざり合った状態で加わる。そこで本例の場合には、これら各荷重Ｆｘ、Ｆｙ、Ｆｚ、Ｍｘ、Ｍｙ、Ｍｚのうちの、上記ハブ２に加わる回転軸（ｙ軸）回りのモーメント荷重Ｍｙを、このハブ２に加わる水平方向の荷重Ｆｘと、車輪３４に固定されたタイヤ３３の半径Ｒとから求める。即ち、上記ハブ２に加わる上記回転軸回りのモーメント荷重Ｍｙを、上記水平方向の荷重Ｆｘと上記タイヤ３３の半径Ｒとの積（Ｍｙ＝Ｒ・Ｆｘ）として求める事ができる。
【００４９】
尚、上記タイヤ３３の半径Ｒは、このタイヤ３３を固定した上記車輪３４の回転速度（＝ハブ２の回転速度）と、車両の速度（車速）とから求められる。即ち、この車輪３４の回転速度（回転数）をＮ［ｍｉｎ−１　］とし、車両の速度をＶ［ｋｍ／ｈ］とした場合に、Ｖ＝１２０π・Ｒ・ｎで表わされる。本例の場合は、このうちの回転速度Ｎを回転速度検出センサ５、５ａ（図１、８）で検出すると共に、上記車速Ｖを次の様にして測定する。即ち、この車速Ｖは、図１５に模式的に示す様に、車両４５の進行方向前側部の下方に設けた画像センサ４６により、この画像センサ４６の検出面に対向する路面４７を一定間隔で撮影し、この画像センサ４６から得られる路面４７の画像の差から算出する。
【００５０】
従来は、上記車両の速度を測定する場合、特開昭６３−６４８６１号公報、同６３−１７０１５７号公報等に記載された様な、ドップラー効果を利用した速度検出装置を使用していた。即ち、車両から照射した超音波やレーザ光の波動がこの車両の速度分だけ速く（遅く）なる現象（ドップラー効果）を利用した速度検出装置により、上記車両の速度を測定していた。これに対して本例の場合には、この車両の速度を、上記画像センサ４６により測定する。具体的には、コンピュータの入力装置として利用されている、光学式マウスの技術を流用する。
【００５１】
即ち、特開平２０００−９７６３９号公報や米国特許第６２８１８８２号明細書には、画像センサにより一定間隔で得られる対象物の画像を比較する（画像のずれを解析する）事により、この対象物の変位を測定する、変位測定装置の発明が記載されている。そして、この様な技術を用いた製品として、コンピュータ入力用マウスに組み込み、このマウスの縦方向及び横方向の変位量を測定する（変位量をデジタル信号に変換自在の）、光学式マウス用の変位測定装置が実際に販売されている。このマウス用の変位測定装置の場合、図１６に示す様に、発光ダイオード（ＬＥＤ）５３から（赤外）レーザ光をレンズ５４を通して対象面であるマウスパット等（本例の場合は路面４７）に向けて照射し、そのレーザ光の反射をレンズ５５を通して画像センサ４６で取り込む。そして、この画像センサ４６で取り込まれる、毎秒２３００フレームの画像を比較する事により、上記マウス（本例の場合は車両４５）の変位を測定する。
【００５２】
尚、この様なマウス用の変位測定装置の場合、１フレームの画像が２２×２２ドット（縦×横）の画素から成り、１インチ８００ドットの解像度、即ち１ドット当たり０．０３１７５ｍｍ程度の解像度を有する。本例の様に車両４５の速度を求める場合、路面４７の模様が大きい事を考慮すると、上記１ドット当たり０．０３１７５ｍｍ程度の解像度は必ずしも必要としない。そこで、本例の場合には、上記路面４７と画像センサ４６との間に設けるレンズの焦点を変える事により、上記解像度を３〜４ｍｍ程度とする。この様に構成すれば、上記マウス用の変位測定装置を車両４５の速度測定装置としてそのまま流用した場合でも、この車両４５の速度を２００Ｋｍ／ｈ程度まで測定する事ができる。
【００５３】
又、この様にして車両４５の速度を測定する場合、走行中に上記画像センサ４６と路面４７との距離が変化する。この為、この画像センサ４６に取り込まれる上記路面４７の画像の大きさが、この距離に応じて変化する事が避けられない。即ち、上記画像センサ４６と路面４７との距離が近付くと、この画像センサ４６により取り込まれる上記路面４７の画像が大きくなり、上記距離が遠ざかると、この路面４７の画像が小さくなる。この為、上記画像センサ４６と路面４７との距離に応じて、この画像センサ４６で取り込まれる上記路面４７の画像の大きさを補正（常に同じ大きさの路面４７の画像を比較できる様に）する必要がある。
この為、本例の場合には、上記画像センサ４６と路面４７との距離を測定する距離測定センサ４８を設け、この距離測定センサ４８により測定される上記距離に応じて、上記画像センサ４６で取り込まれる路面４７の画像の大きさを補正する。
【００５４】
この様な距離測定センサ４８としては、例えば特開平８−１２２０５６号公報等に記載された様な、三角測量方式による光学式測距センサ（距離測定センサ）が使用可能である。即ち、発光ダイオード等の発光部から（赤外）レーザ光を対象面（路面４７）に向けて照射すると共に、このレーザ光の反射を受光部で取り込み、このレーザ光の出射角度と入射角度、並びに上記発光部と受光部との距離とから、上記距離測定センサと対象面との距離を求める。この様な技術を用いた距離測定センサの場合、複写機で原稿用紙の大きさを測定する為の用紙検出センサとして安価に使用されている。又、本例の様に画像センサ４６と路面４７との距離を測定する場合に必要とされる、０．２〜１．５ｍ程度の距離を高精度に測定できるものも、一般に市販されている。
【００５５】
従って、この様な距離測定センサにより上記画像センサ４６と路面４７との距離を測定すれば、上記マウス用の変位測定装置と共に上記車両４５の速度測定装置を安価に構成できる。又、この場合に、上記マウス用の変位測定装置と上記距離測定装置との発光部（発光ダイオード）を共用できる為、上記速度測定装置の寸法が嵩む事も防止できる。尚、この様な速度測定装置を車両４５に取り付ける場合、図１７に示す様な筒状の保護カバー４９をこの速度測定装置の各検出部に設け、運転時に泥や雨水等の異物がこれら各検出部に付着する事を防止する。又、この速度測定装置の車両への取付位置は、前述の図１５に示す様な車両４５の進行方向前側部分に限られず、この車両４５の中間部や同じく後側部分に取り付ける事も可能である。
【００５６】
尚、本例の場合には、前述の様に、上述の様な速度測定装置で測定される車両４５の速度（車速）と、前記回転速度検出センサ５、５ａ（図１、８）で測定される車輪３４の回転速度（＝ハブ２の回転速度）とから、この車輪３４に固定されたタイヤ３３の半径Ｒ（図５）を求める。この為、雪道や悪路等でタイヤ３３がスピン（空転）或はロック（固定）すると、上記回転速度検出センサ５、５ａで測定される車輪３４の回転速度が上記車速に比べて極端に増減し、これに伴って上記タイヤ３３の半径Ｒの値も極端に変化（増減）する。この様な場合には、このタイヤ３３の半径Ｒとこのタイヤ３３に加わる前記水平方向の荷重Ｆｘとの値から、前記車輪支持用転がり軸受ユニットを構成するハブ２に加わる、回転軸（ｙ軸）回りのモーメント荷重Ｍｙ（Ｍｙ＝Ｒ・Ｆｘ）を正確に求められなくなる。
【００５７】
但し、上述の様なタイヤ３３の半径Ｒの値の極端な変化は、このタイヤ３３がバースト（急激に破損、破裂）する場合を除いて生じにくい。この為、この様にタイヤ３３の半径Ｒの値が極端に変化する場合には、前述した各変位測定素子２７ａ、２７ｂにより求められる、上記ハブ２に加わる荷重の種類、方向、大きさに基づいて、上記タイヤ３３がスピン、ロック或はバーストしたかを判断する。
そして、このタイヤ３３がスピン、ロックしたと判断される場合には、前記制御器のメモリに予め保存しておいた（記憶させておいた）タイヤ３３の半径Ｒの値から、上記モーメント荷重Ｍｙ（Ｍｙ＝Ｒ・Ｆｘ）を求める。尚、この様に制御器のメモリに保存するタイヤ３３の半径Ｒの値は、所定間隔で補正する（測定し直す）事が好ましい。（タイヤ３３の空気が漏れたり積載重量が大きく変わらない限り殆どその値は変わらないが、）この様に所定間隔でタイヤ３３の半径Ｒの値を補正する事により、上記メモリに保存された値と実際の値とが大きく異なる事を防止する。
【００５８】
又、上述の様に求められるタイヤ３３の半径Ｒと、前述した各変位測定素子２７ａ、２７ｂにより求められる上記ハブ２に加わる荷重の種類、方向、大きさとに基づいて、上記タイヤ３３の空気圧の減少量や変形量を推定する事もできる。
例えば、上記タイヤ３３の半径Ｒの値と上記ハブ２に加わる鉛直方向の荷重Ｆｚ（図５参照）とから、或は上記メモリに保存されたタイヤ３３の半径Ｒの値と実際の測定値との差により、上記タイヤ３３の空気が漏れた（減少した）か否かを判断できる。そして、このタイヤ３３の空気圧が減少したと判断される場合には、運転者にその旨を知らせ、このタイヤ３３に空気の補給をする事を促す。この結果、空気圧が減少した状態で走行する事を防止でき、車両４５の走行が不安定になったり、高速走行時に上記タイヤ３３が波打って（スタンディングウエーブが生じて）バーストし易くなる事を防止できる。又、上記タイヤ３３の半径Ｒの減少量や変形量が急激な場合には、運転者に危険である旨を警報音等により知らせ、走行停止や空気の補給、更にはタイヤ３３の交換等を促す。
【００５９】
上述の様な本例の場合には、前述の様に車輪支持用転がり軸受ユニットを構成するハブ２に加わる荷重の種類、方向、大きさを、この車輪支持用転がり軸受ユニットに付与された予圧の値を考慮してより高精度で求められる。又、これと共に、車両４５の速度やタイヤ３３の半径Ｒを、測定装置のコストが嵩む事なくより高精度に求められる。この為、ＡＢＳやＴＣＳ、ＶＳＣ等の制御を高度且つ適正に行なえる。
【００６０】
例えば、雑誌「自動車技術」（Ｖｏｌ．５４，Ｎｏ６，２０００　）の「自動車技術基礎講座−第１５回」には、ＡＢＳ、ＴＣＳ、ＶＳＣの技術が記載されている。そして、このうちのＡＢＳに就いては、所定のスリップ率｛（車速−車輪の回転速度）／車速｝となる様にブレーキ圧を制御する事により、タイヤのロックを防止しつつ車両を減速させる技術が記載されている。本例の場合、前述の様に車両４５の速度や車輪４４の回転速度を高精度に測定できる為、上記スリップ率を正確に得られる。又、これと共に、車両の減速時に制動力として得られる、上記ハブ２に加わる水平方向の荷重Ｆｘ（図５）も高精度に求められる為、上記スリップ率を所定の値とする為の上記ブレーキ圧の制御を、高度且つ適正に行なう事ができる。又、上記ＴＣＳ、ＶＳＣの制御を行なう場合にも、ハブ２に加わる各種荷重Ｆｘ、Ｆｙ、Ｆｚ、Ｍｘ、Ｍｙ、Ｍｚ（図５）を本例の様に高精度に求める事ができれば、より高次元で車両制御を行なう事ができる。
【００６１】
又、特開平３−２２００５６号公報には、タイヤと路面との摩擦力を検出し、その摩擦力が増大する間にブレーキ圧を上昇させる事により、このタイヤのロックを防止しつつ車両を減速させる、アンチロックブレーキ装置の発明が記載されている。図１８に示す様に、タイヤ３３と路面４７との摩擦力μは、その反力として上記ハブ２に、水平方向の荷重Ｆｘとして加わる。従って、この荷重Ｆｘを高精度に求められる本例の場合には、上述の様な車両制御をより高次元で行なう事ができる。
【００６２】
又、特開平１１−２５５０９１号公報には、荷重センサから得られる各方向の荷重から、ニューラルネットワーク（人工知能）のアルゴリズムを用いて最適な制御を行なう、ＡＢＳ装置の発明が記載されている。この公報に記載された発明の場合にも、本例の様にハブ２に加わる各荷重を高精度に求められれば、より高次元の制御を行なえる。
【００６３】
次に、図１９〜２０は、本発明の実施の形態の第５例を示している。本例の場合は、ラジアル方向並びにスラスト方向の変位を検出する為の各変位測定素子２７ａ、２７ｂのうちの、ラジアル方向の変位を検出する変位測定素子２７ａにより、このラジアル方向の変位と共に回転速度も検出自在としている。即ち、本例の場合は、被検出リング２９ｂを構成する被検出用円筒部５０の一部で上記ラジアル方向の変位を検出する変位測定素子２７ａに近接対向する部分に、除肉部として機能する多数の透孔５１、５１を、円周方向に関して等間隔に形成している。これら各透孔５１、５１は、軸方向に長いスリット状である。又、円周方向に隣り合うこれら各透孔５１、５１同士の間部分は、充実部として機能する柱部としている。
【００６４】
この様な透孔５１、５１を有する上記被検出リング２９ｂが回転すると、上記変位測定素子２７ａの（波形成形処理後の）出力は、図２１の実線αに示す様に変化する。即ち、上記被検出用円筒部５０の各透孔５１、５１と上記変位測定素子２７ａとが対向する際に、この変位測定素子２７ａの出力が低下し、同じく上記各透孔５１、５１同士の間部分である各柱部と対向する際に、上記変位測定素子２７ａの出力が増大する。この様な変位測定素子２７ａの出力が変化する周波数は、車輪の回転速度に比例する為、出力信号を上記ハーネスを通じて図示しない制御器に入力すれば、上記車輪の回転速度を求める事ができる。又、上記ラジアル方向の変位を検出する変位測定素子２７ａと上記被検出リング２９ｂの内周面との距離は、上記被検出用円筒部５０のうちの上記各透孔５１、５１同士の間部分である各柱部と上記変位測定素子２７ａとが対向した際の、この変位測定素子２７ａの出力の大きさから求める事ができる。
【００６５】
上述の様に構成する本例の場合には、外輪１に回転速度検出センサ５ａ（図８参照）を取り付ける為の取付孔２３ｂを設ける必要がない。この為、この外輪１の加工作業が容易になってコスト低減を図れる他、この外輪１の肉厚を特に大きくしなくても、この外輪１の強度確保を図れる。しかも、上記外輪１に設けた回転速度検出センサ５ａと制御器との間のハーネスも省略できる為、ハーネスの取り回しも容易になって、荷重測定装置付車輪支持用転がり軸受ユニットを懸架装置に組み付ける作業の容易化を図れる。その他の部分の構成及び作用は、前述した第４例の場合と同様である。
【００６６】
次に、図２２〜２３は、本発明の実施の形態の第６例を示している。本例の場合は、外輪１に対するハブ２のラジアル方向及びスラスト方向の変位を測定する変位センサユニット２６ｂ内に、上記ハブ２の回転速度を測定する回転速度検出センサ５ｂを設けている。即ち、上記外輪１の内端開口部を塞いだカバー４に固定した、合成樹脂中に変位測定素子２７ａ、２７ｂを包理して成る上記変位センサユニット２６ｂ内に、上記回転速度検出センサ５ｂを構成する回転速度検出素子５２も包理支持している。
【００６７】
この回転速度検出素子５２は、図２２に示す様に、上記変位センサユニット２６ｂ内で、上記各変位測定素子２７ａ、２７ｂから軸方向に外れた部分、若しくは、図２３に示す様に、円周方向に隣り合う変位測定素子２７ａ、２７ｂ同士の間部分に位置させる。この様な回転速度検出素子５２としては、上記各変位測定素子２７ａ、２７ｂと同様に、各種構造のものを使用できるが、本例の場合は、上記変測定素子２７ａ、２７ｂと同様の渦電流式のものとしている。一方、被検出リング２９ｃを構成する被検出用円筒部５０の軸方向内端寄り部分で、上記回転速度検出素子５２と近接対向する部分に多数の透孔５１を、円周方向に関して等間隔に形成している。そして、前述した実施の形態の第５例の場合と同様に、上記回転速度検出素子５２の出力の変化から、回転速度を検出する。
【００６８】
尚、上記被検出リング２９ｃとして鋼板等の磁性金属板のものを使用する場合には、上記回転速度検出素子５２として、ホール素子、ＭＲ素子等の通過磁束量に応じて特性を変化させる磁気検出素子を使用する事もできる。この様な磁気検出素子を使用する場合には、被検出リング２９ｃを構成する被検出用円筒部５０の軸方向内端寄り部分で、上記回転速度検出素子５２と近接対向する部分の磁気特性を、円周方向に関して交互に（一般的には等間隔に）変化させる。
【００６９】
この様に円周方向に関して磁気特性を交互に変化させる為には、円周方向に亙り多数の除肉部と充実部とを交互に形成したり、或はＳ極とＮ極とを交互に配置した永久磁石を添着したりする。前者の場合には、上記被検出リング２９ｃを構成する被検出用円筒部５０の軸方向内端寄り部分で上記回転速度検出素子５２と近接対向する部分に多数の透孔５１を、円周方向に関して等間隔に形成する。この場合には、前記回転速度検出センサ５ｂに、上記被検出リング２９ｃの径方向に着磁した永久磁石を組み込む。或は、この様な透孔５１を形成する事に代えて、上記被検出用円筒部５０の軸方向内端寄り部分の内周面に、Ｓ極とＮ極とを円周方向に関して交互に且つ等間隔で配置した（着磁した）永久磁石を添着する。
この場合には、上記回転速度検出センサ５ｂ側の永久磁石は不要である。
【００７０】
上述の様な、磁気特性を円周方向に亙って交互に且つ等間隔で変化させた被検出リング２９ｃが回転すると、上記磁気検出素子である回転速度検出素子５２の近傍部分を、上記透孔５１とこれら各透孔５１同士の間に存在する柱部とが、或はＳ極とＮ極とが、交互に通過する。この結果、上記回転速度検出素子５２内を流れる磁束量（或は磁束の方向）が変化し、この回転速度検出素子５２を組み込んだ上記回転速度検出センサ５ｂの出力が変化する。この出力が変化する周波数は、車輪の回転速度に比例する為、出力信号を上記ハーネスを通じて制御器に入力すれば、上記車輪の回転速度を求める事ができる。その他の部分の構成及び作用は、前述した第５例の場合と同様である。
【００７１】
次に、図２４は、本発明の実施の形態の第７例を示している。前述した実施の形態の各例は何れも、各転動体１０、１０よりも径方向に関して外側に存在する外輪１（例えば図１参照）を、使用状態で懸架装置に支持固定される静止側軌道輪とすると共に、同じく径方向に関して内側に存在するハブ２（例えば図１参照）を、使用状態で車輪を支持固定する回転側軌道輪としている。これに対して本例の場合には、使用状態で図示しない支持軸に外嵌固定する、静止側軌道輪である１対の内輪８、８の径方向外側に、使用状態で車輪を支持固定するハブ２ａを、複数個の転動体１０、１０を介して回転自在に支持している。
【００７２】
又、上記１対の内輪８、８のうちの軸方向内側に位置する内輪８の内端部外周面に、合成樹脂中に変位測定素子２７ａ、２７ｂを包理して成る変位センサユニット２６ｃを支持している。そして、上記各変位測定素子２７ａ、２７ｂのうちの、ラジアル方向の変位を検出する為の変位測定素子２７ａを、上記ハブ２ａの内端部外周面に（被検出リングを介さないで）直接近接対向させると共に、同じくスラスト方向の変位を検出する為の変位測定素子２７ｂを、上記ハブ２ａの内端面に（被検出リングを介さないで）直接近接対向させている。その他の部分の構成及び作用は、前述した第６例の場合と同様である。
【００７３】
【発明の効果】
本発明の荷重測定装置付車輪支持用転がり軸受ユニットは、以上に述べた通り構成され作用する為、走行時に車輪に加わる荷重の方向及び大きさを測定できて、車両の走行安定性を損なう要因を予め検出し、これに対応する事を可能にでき、車両の安全運行に寄与できる。又、構成部品が少なく、しかも重量の嵩む構成部品を使用する必要がない為、ばね下荷重を抑えて、乗り心地を中心とする走行性能を悪化させる事なく、上記測定を高精度に行なえる。
【図面の簡単な説明】
【図１】本発明の実施の形態の第１例を示す断面図。
【図２】変位センサユニットの設置状態を、一部を省略して示す、図１の略Ａ−Ａ断面図。
【図３】ラジアル、スラスト両検出部と上記ラジアル、スラスト両被検出面との対向状態を示す、図１のＢ部に相当する図。
【図４】モーメント荷重に基づいてハブの回転中心が傾斜した状態を誇張して示す断面図。
【図５】タイヤ及び車輪を介してハブに加わる荷重を模式的に示す斜視図。
【図６】本発明の実施の形態の第２例を示す、図２と同様の断面図。
【図７】同第３例を示す、図２と同様の断面図。
【図８】同第４例を示す断面図。
【図９】図８のＣ部拡大図。
【図１０】被検出リングと変位センサユニットの変位測定素子とを取り出して図８の右方から見た図。
【図１１】磁気誘導式の変位測定素子の原理を示す斜視図。
【図１２】渦電流式の変位測定素子の原理を示す斜視図。
【図１３】渦電流式の変位測定素子を構成するコイルのインピーダンスを変換する回路（ブリッジ法）を示す図。
【図１４】本発明の実施の形態の第４例の変形例を示す、図９と同様の断面図。
【図１５】車両の速度測定装置の取付状態を示す模式図。
【図１６】車両の速度測定装置の構造を説明する為の模式図。
【図１７】車両の速度測定装置のセンサに取り付ける保護カバーを示す斜視図。
【図１８】タイヤを介して車輪に加わる水平方向（進行方向）の荷重を模式的に示す側面図。
【図１９】本発明の実施の形態の第５例を示す断面図。
【図２０】図１８のＤ部拡大図。
【図２１】変位測定素子の出力変化を示す線図。
【図２２】本発明の実施の形態の第６例を示す部分断面図。
【図２３】変位センサユニットの設置状態を、一部を省略して示す、図１０と同様の図。
【図２４】本発明の実施の形態の第７例を示す半部断面図。
【図２５】従来構造の第１例を示す断面図。
【図２６】同第２例を示す断面図。
【符号の説明】
１　　外輪
２、２ａ　ハブ
３、３ａ　センサロータ
４　　カバー
５、５ａ、５ｂ　回転速度検出センサ
６　　外輪軌道
７　　ナット
８　　内輪
９　　内輪軌道
１０　　転動体
１１　　保持器
１２　　フランジ
１３　　取付部
１４　　シールリング
１５　　被検出用円筒部
１６　　支持用円筒部
１７　　透孔
１８　　嵌合筒部
１９　　塞ぎ板部
２０　　通孔
２１　　コネクタ
２２　　スタッド
２３、２３ａ、２３ｂ　取付孔
２４　　変位センサ
２５　　センサリング
２６、２６ａ、２６ｂ、２６ｃ　変位センサユニット
２７ａ、２７ｂ　変位測定素子
２８　　ホルダ
２９、２９ａ、２９ｂ　被検出リング
３０　　円筒部
３１　　折れ曲がり部
３２　　ハーネス
３３　　タイヤ
３４　　車輪
３５　　鉄芯
３６　　第一のコイル
３７　　第二のコイル
３８　　フェライト芯
３９　　コイル
４０　　基準コイル
４１　　抵抗
４２　　水晶発振器
４３　　ブリッジ回路
４４、４４ａ　絶縁材
４５　　車両
４６　　画像センサ
４７　　路面
４８　　距離測定センサ
４９　　保護カバー
５０　　被検出用円筒部
５１　　透孔
５２　　回転速度検出素子
５３　　発光ダイオード
５４　　レンズ
５５　　レンズ[0001]
TECHNICAL FIELD OF THE INVENTION
A wheel supporting rolling bearing unit with a load measuring device according to the present invention rotatably supports a wheel of a vehicle (automobile) with respect to a suspension device, and measures a direction and a magnitude of a force applied to the wheel, This contributes to stable operation of the vehicle.
[0002]
[Prior art]
A rolling bearing unit is used to rotatably support wheels of a vehicle with respect to a suspension device. Further, in order to control the antilock brake system (ABS) and the traction control system (TCS), it is necessary to detect the rotation speed of the wheels. Therefore, it is possible to support the wheel rotatably with respect to the suspension device and detect the rotation speed of the wheel by a rolling bearing unit with a rotation speed detection device incorporating the rotation speed detection device in the rolling bearing unit. In recent years, it has been widely practiced.
[0003]
FIG. 25 shows, as an example of a conventional structure used for such a purpose, a rolling bearing unit for supporting a wheel with a rotation speed detecting device described in JP-A-2001-21577. The wheel supporting rolling bearing unit with the rotation speed detecting device is provided with a wheel on the inner diameter side of the outer race 1 corresponding to the stationary raceway according to claim, which does not rotate during use while being supported by the suspension device. The hub 2 which rotates in use in a fixed state and corresponds to the rotating raceway described in the claims is supported. The rotation speed of the sensor rotor 3 fixed to a part of the hub 2 can be detected by a rotation speed detection sensor 5 supported on a cover 4 fixed to the outer race 1. In the illustrated example, an annular sensor that faces the sensor rotor 3 over the entire circumference is used as the rotational speed detection sensor 5. Further, in order to rotatably support the hub 2, double rows of outer raceways 6, 6 each corresponding to the stationary raceway described in the claims are provided on the inner peripheral surface of the outer race 1. In addition, the outer peripheral surface of the hub 2 and the outer peripheral surface of the inner ring 8 which constitutes the rotation-side raceway ring together with the hub 2 in a state of being externally fitted to the hub 2 and fixed to the hub 2 by a nut 7, respectively. Are provided with inner ring raceways 9, 9 corresponding to the rotation-side race described in the claims. A plurality of rolling elements 10, 10 are provided between the inner raceways 9, 9 and the outer raceways 6, 6, respectively, in such a manner that the rolling bodies 10, 10 are held by holders 11, 11 so as to freely roll. The hub 2 and the inner ring 8 are rotatably supported inside the outer ring 1.
[0004]
In addition, at the outer end of the hub 2 (the end that is outward in the width direction when assembled to a vehicle, and the left end in FIG. 25), a portion protruding outward in the axial direction from the outer end of the outer race 1 , A flange 12 for mounting a wheel is provided. Further, a mounting portion 13 for mounting the outer ring 1 to a suspension device is provided at an inner end portion of the outer ring 1 (an end portion which is located on the center in the width direction when assembled to a vehicle, and is a right end portion in FIG. 25). ing. A gap between the outer end opening of the outer race 1 and the outer peripheral surface of the intermediate portion of the hub 2 is closed by a seal ring 14. In the case of a heavy-weight rolling bearing unit for a vehicle, tapered rollers may be used as the plurality of rolling elements 10 and 10 instead of balls as illustrated.
[0005]
In order to incorporate the rotation speed detecting device into the rolling bearing unit as described above, the sensor rotor 3 is externally fixed to the outer peripheral surface of the inner end of the inner race 8 at the portion deviating from the inner raceway 9. The sensor rotor 3 is formed in a ring shape as a whole by subjecting a magnetic metal plate such as a mild steel plate to plastic working, and includes a detection target cylindrical portion 15 and a support cylindrical portion 16 which are concentric with each other. Of these, the supporting cylindrical portion 16 is fixed to the inner end of the inner ring 8 by tightly fitting the outer cylindrical portion 16 to the inner end of the inner ring 8.
Further, the detection target cylindrical portion 15 is formed with a large number of slit-shaped through holes 17, 17 each of which is long in the axial direction of the detection target cylindrical portion 15, and is formed at equal intervals in the circumferential direction. The magnetic characteristics of the detection target cylindrical portion 15 are changed alternately at regular intervals in the circumferential direction.
[0006]
Further, the cover 4 is fitted and fixed to the inner end opening of the outer ring 1 so as to cover the detection target cylindrical portion 15 of the sensor rotor 3, thereby closing the inner end opening of the outer ring 1. . The cover 4, which is formed by plastically processing a metal plate, has a fitting cylindrical portion 18 that can be fitted and fixed in the inner end opening of the outer race 1, and a closing plate portion 19 that closes the inner end opening. The rotation speed detection sensor 5 is held and fixed in the closing plate portion 19. Further, a through hole 20 is formed in a portion near the outer periphery of the closing plate portion 19, and a connector 21 for taking out the output of the rotation speed detection sensor 5 is taken out of the cover 4 through the through hole 20. With the rotation speed detection sensor 5 held and fixed in the cover 4 in this manner, the detection unit provided on the outer peripheral surface of the rotation speed detection sensor 5 is provided inside the detection target cylindrical portion 15 constituting the sensor rotor 3. It faces the peripheral surface via a minute gap.
[0007]
When using the rolling bearing unit for supporting a wheel with the rotation speed detecting device as described above, the mounting portion 13 fixed on the outer peripheral surface of the outer ring 1 is fixedly connected to the suspension device with a bolt (not shown), and A wheel (not shown) is fixed to a flange 12 fixed to the outer peripheral surface of the hub 2 by a stud 22 provided on the flange 12, so that the wheel is rotatably supported by the suspension device. When the wheel rotates in this state, the vicinity of the end face of the detection portion of the rotation speed detection sensor 5 is changed to the through holes 17 and 17 formed in the detection target cylindrical portion 15 and the through holes 17 and 17 circumferentially adjacent to each other. The pillars existing between them alternately pass. As a result, the density of the magnetic flux flowing in the rotation speed detection sensor 5 changes, and the output of the rotation speed detection sensor 5 changes. The frequency at which the output of the rotation speed detection sensor 5 changes in this way is proportional to the rotation speed of the wheel. Therefore, if the output of the rotation speed detection sensor 5 is sent to a controller (not shown), the ABS and TCS can be appropriately controlled.
[0008]
That is, the output of the rotation speed detection sensor 5 is compared with the output of an acceleration sensor separately provided on the vehicle body side, and when the outputs of these two sensors are not consistent, the contact between the outer peripheral surface of the tire and the road surface is determined. The ABS or TCS is controlled by judging that the contact portion has slipped. That is, if the wheel deceleration obtained based on the output of the rotation speed detection sensor 5 is larger than the vehicle deceleration detected by the acceleration sensor during braking, it is determined that the slip has occurred. By controlling the oil pressure of the wheel cylinder portion of the brake device, it is possible to prevent the rotation of the wheels from stopping before the vehicle stops, thereby ensuring the stability of the running posture of the vehicle. Also, when accelerating, when the vehicle acceleration obtained by the acceleration sensor is smaller than the wheel acceleration obtained based on the output of the rotational speed detection sensor 5 (or the driving wheel acceleration is smaller than the driven wheel acceleration). If the acceleration is large), it is determined that the slippage has occurred, and braking is applied to the wheels or the output of the engine is reduced (reduced), so that the outer peripheral surface of the tire and the road surface are To prevent the vehicle from slipping and to stabilize the running posture of the vehicle.
[0009]
According to the conventionally known wheel supporting rolling bearing unit with a rotation speed detecting device as described above, the stability of the running posture of the vehicle during braking or acceleration can be ensured, but even in more severe conditions. In order to ensure this stability, it is necessary to control the brakes and the engine by incorporating more information that affects the running stability of the vehicle. In contrast, in the case of an ABS or TCS using a conventional rolling bearing unit with a rotation speed detecting device, a so-called feedback control is performed in which a slip between a tire and a road surface is detected to control a brake or an engine. . For this reason, the control of these brakes and the engine is delayed even for a moment, and therefore, improvement is demanded from the aspect of performance improvement under severe conditions. That is, in the case of the conventional structure, the so-called feed-forward control prevents slipping from occurring between the tire and the road surface or prevents the so-called one-sided braking effect in which the braking forces of the left and right wheels are extremely different. Can not. Further, it is impossible to prevent running stability from being deteriorated on the basis of a poor loading state of a truck or the like.
[0010]
In view of such circumstances, Japanese Patent Application Laid-Open No. 2001-21577 describes a structure, as shown in FIG. 26, in which a load applied to a rolling bearing unit can be freely measured. In the case of the second example of this conventional structure, a mounting hole 23 that penetrates the outer ring 1 in the diametric direction is provided in a portion between the pair of outer ring raceways 6, 6 at an intermediate portion in the axial direction of the outer ring 1, 1 is formed substantially vertically at the upper end. A rod-shaped (rod-shaped) displacement sensor 24 is mounted in the mounting hole 23. The detection surface provided on the front end surface (lower end surface) of the displacement sensor 24 is closely opposed to the outer peripheral surface of the sensor ring 25 which is externally fixed to the axially intermediate portion of the hub 2. When the distance between the detection surface and the outer peripheral surface of the sensor ring 25 changes, the displacement sensor 24 outputs a signal corresponding to the change amount.
[0011]
In the case of the second example of the conventional structure configured as described above, the load applied to the wheel supporting rolling bearing unit incorporating the displacement sensor 24 can be obtained based on the detection signal of the displacement sensor 24. That is, the outer ring 1 supported by the suspension system of the vehicle is pushed downward by the weight of the vehicle, while the hub 2 supporting and fixing the wheels tends to stop at the same position. Therefore, as the weight increases, the deviation between the center of the outer ring 1 and the center of the hub 2 increases based on the elastic deformation of the outer ring 1 and the hub 2 and the rolling elements 10 and 10. The distance between the detection surface of the displacement sensor 24 and the outer peripheral surface of the sensor ring 25 provided at the upper end of the outer ring 1 becomes shorter as the weight increases. Then, if the detection signal of the displacement sensor 24 is sent to the controller, the load applied to the wheel supporting rolling bearing unit incorporating the displacement sensor 24 can be determined from a relational expression or the like determined in advance by experiments or the like. Based on the load applied to each wheel supporting rolling bearing unit thus obtained, the ABS is appropriately controlled, and the driver is notified of a defective loading condition.
[0012]
In the case of the second example of the conventional structure shown in FIG. 26, the load applied in the vertical direction can be measured based on the weight of the vehicle, but, for example, the moment load applied based on the centrifugal force or the like during turning can not be measured. Therefore, improvement is desired from the viewpoint of obtaining a signal for performing appropriate control for stable running according to all running states of the vehicle. As a structure that can be used in such a case, a structure described in Japanese Patent Application Laid-Open No. 10-73501 is known. According to the structure described in this publication, it is possible to measure loads in each direction applied to the wheels when the vehicle travels, including the moment load.
[0013]
[Problems to be solved by the invention]
The conventional structure described in the above-mentioned Japanese Patent Application Laid-Open No. 10-73501 has many members to be added for load measurement and includes large-sized members, so that it is inevitable that the cost and weight increase. The part where the load measuring device is assembled is closer to the wheel than the spring that forms the suspension device, and the components of this load measuring device are so-called unsprung loads, and even a small amount of weight deteriorates the running performance mainly in the riding comfort. Therefore, improvement is desired in order to be linked.
[0014]
In recent years, in order to control the vehicle stability control system (VSC) which secures the lateral stability of the vehicle by controlling the ABS and TCS, and furthermore, the engine output and the brake, etc. Along with the measured values of the load measuring device, it is required to measure the vehicle speed and the like with higher accuracy. In addition to such high accuracy, there is also a demand for lower cost of the load measuring device and the vehicle speed measuring device.
The rolling bearing unit for supporting a wheel with a load measuring device of the present invention was invented in view of such circumstances.
[0015]
[Means for Solving the Problems]
A wheel supporting rolling bearing unit with a load measuring device of the present invention includes a wheel supporting rolling bearing unit and a load measuring device.
The rolling bearing unit for supporting the wheel includes a stationary raceway that is supported and fixed to the suspension device in use, a rotating raceway that supports and fixes the wheel in use, and a stationary raceway and a rotating raceway. It is provided with a plurality of rolling elements provided between a stationary-side orbit and a rotating-side orbit present on peripheral surfaces of the wheel facing each other.
Further, the load measuring device includes a cylindrical radial detection surface provided concentrically with the rotation center of the rotating raceway, and a thrust detection surface provided in a direction perpendicular to the rotation center of the rotation raceway. And at least one displacement sensor unit provided on the stationary side race.
The displacement sensor unit includes a radial detection unit and a thrust detection unit, and measures a distance between the radial detection unit and the radial detection surface and a distance between the thrust detection unit and the thrust detection surface. It is flexible.
Further, a load applied to the rotating raceway is determined from the respective distances measured from the displacement sensor unit and a value of the preload determined in advance to the wheel supporting rolling bearing unit.
[0016]
[Action]
According to the rolling bearing unit for supporting a wheel with a load measuring device of the present invention configured as described above, not only the radial displacement but also the thrust displacement of the rotating raceway can be measured. Then, based on the displacement in each direction detected by the displacement sensor unit, the load in each direction applied to the wheel supporting rolling bearing unit can be obtained. In addition, since the load applied in each of these directions is determined in consideration of the value of the preload applied to the wheel supporting rolling bearing unit, the load applied in each direction to the wheel supporting rolling bearing unit can be determined with high accuracy. Control of ABS, TCS, VSC, etc., can be performed in an advanced and appropriate manner.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
1 to 4 show a first example of an embodiment of the present invention. The feature of this example is that a structure is obtained in which the direction and magnitude of a load applied to a wheel (not shown) fixed to the hub 2 are obtained, and the ABS, TCS, VSC and the like can be appropriately controlled. For this reason, in the case of this example, not only the load applied to the hub 2 but also the rotation speed of the hub 2 can be detected. However, since the structure and operation of the portion for detecting the rotational speed are the same as those of the conventional structure shown in FIGS. 25 to 26, the same reference numerals are given to the same portions and the repeated description will be omitted. Hereinafter, description will be made focusing on the characteristic portions of the present invention.
[0018]
In the case of this example, mounting holes 23a, 23a are provided at four circumferentially equally spaced positions in the axially intermediate portion of the outer race 1 located between the double-row outer raceways 6, 6, respectively. Are formed in a state where the inner and outer peripheral surfaces thereof communicate with each other. In the case of this example, two of the four mounting holes 23a, 23a are formed in the vertical direction, and the remaining two mounting holes 23a, 23a are formed in the horizontal direction. The displacement sensor units 26, 26 are inserted into the respective mounting holes 23a, 23a.
[0019]
Each of these displacement sensor units 26, 26 is capable of measuring the displacement of the hub 2 in the radial direction (radial direction) and the displacement of the hub 2 in the thrust direction (axial direction). Has the displacement measuring elements 27a and 27b. That is, each of the displacement measuring elements 27a and 27b which can measure a minute displacement in a non-contact manner, such as a capacitance type proximity sensor, is replaced with a synthetic resin holder 28 constituting each of the displacement sensor units 26 and 26. And embedded in and supported by the distal end surface portion and the distal end side surface portion. Among the displacement measuring elements 27a and 27b, the displacement measuring element 27a embedded and supported on the distal end surface of the holder 28 constitutes a radial detection unit, and the displacement measuring element 27b embedded and supported on the distal end side surface is provided. It constitutes a thrust detector.
[0020]
On the other hand, a detection ring 29 is externally fitted and fixed to an intermediate portion of the hub 2 located between the inner and outer raceways 9, 9 in a double row. The ring to be detected 29 is formed by subjecting a metal plate to plastic working such as press working so as to have an L-shaped cross section and an annular shape as a whole, and includes a cylindrical portion 30 and one axial end portion of the cylindrical portion 30 (see FIG. (Right end portions 1 and 3) and a bent portion 31 bent radially outward at a right angle. In the case of this example, the outer peripheral surface of the cylindrical portion 30 is a radial detection surface, and one side surface (the left side surface in FIGS. 1 and 3) of the bent portion 31 is a thrust detection surface.
[0021]
The detection units of the displacement-side measuring elements 27a and 27b of the displacement sensor units 26 and 26 are arranged to face the detection ring 29 as described above. That is, the displacement measuring element 27a that constitutes the radial detection unit is closely opposed to the outer peripheral surface of the cylindrical portion 30, which is the radial detection surface. Then, the displacement of the hub 2 with respect to the outer ring 1 in the radial direction (radial direction) can be freely measured by the displacement measuring element 27a. Further, the displacement measuring element 27b constituting the thrust detecting portion is made to closely approach one side surface of the bent portion 31, which is the thrust detection surface. Then, the displacement of the hub 2 with respect to the outer ring 1 in the thrust direction (axial direction) can be freely measured by the displacement measuring element 27b.
[0022]
In the case of the rolling bearing unit for supporting a wheel with a load measuring device according to the present embodiment, as described above, the hub for the outer ring 1 is provided at four positions in the circumferential direction by the four displacement sensor units 26, 26. 2 is configured to measure the displacement in the radial and thrust directions. A total of eight types of detection signals, two types for each of the displacement sensor units 26, 26, measured by the displacement sensor units 26, 26, are taken out by harnesses 32, 32, respectively, and input to a controller (not shown). I have. Then, based on the detection signals sent from the displacement sensor units 26, 26, the controller determines the loads in the respective directions applied to the wheel supporting rolling bearing units.
[0023]
For example, when a load in the vertical direction (downward) based on the vehicle weight or the like is applied to each of the wheel supporting rolling bearing units, the upper one of the two displacement sensor units 26, 26 existing in the vertical direction. In the displacement sensor unit 26, the distance between the displacement measuring element 27a constituting the radial detection unit and the outer peripheral surface of the cylindrical portion 30, which is the surface to be radially detected, is reduced. Spreads. The amount of change in the distance at this time increases as the load increases. This distance does not change for the two displacement sensor units 26, 26 existing in the horizontal direction (front-back direction).
[0024]
On the other hand, if a load in the horizontal direction is applied to the hub 2 for some reason (for example, due to acceleration or braking), of the two displacement sensor units 26, 26 existing in the horizontal direction, In the displacement sensor unit 26 on the front side in the working direction, the distance between the displacement measuring element 27a constituting the radial detection unit and the outer peripheral surface of the cylindrical portion 30 as the radial detection surface is reduced, This distance is increased by the displacement sensor unit 26. The amount of change in the distance at this time also increases as the load increases. With respect to the two displacement sensor units 26, 26 existing in the vertical direction, this distance does not change. Depending on the load in the oblique direction, the distance changes for all the sensor units 26, 26.
[0025]
Therefore, comparing the detection signals of the displacement measuring elements 27a, 27a constituting the radial detection units of the four displacement sensor units 26, 26 arranged at equal intervals in the circumferential direction, the direction in which the radial load acts and the You can know the size. The amount of change in the distance between the above-mentioned parts, the magnitude of the radial load, and the acting direction are obtained in advance by a calculation formula, a number of experiments, or computer analysis. In particular, particularly in the case of this example, as will be described later, in consideration of the value of the preload applied to the wheel supporting rolling bearing unit, the amount of change in the distance between the above-described portions, the magnitude of the radial load and the direction of action are determined. Find the relationship.
[0026]
Next, a vertical moment load, that is, a moment load Mx in a direction indicated by Mx in FIG. 5 is applied to the hub 2 by turning or the like, and the center axis of the hub 2 and the center axis of the outer ring 1 are (vertical). A description will be given of the case where there is a mismatch (in the direction). In this case, the direction and magnitude of the moment load Mx are determined based on the detection signals of the displacement measuring elements 27b, 27b, which constitute the thrust detecting sections of the displacement sensor units 26, 26. For example, a large moment load Mx is applied in a clockwise direction in FIG. 4 to the hub 2 supporting the outer wheels (in the radial direction of the turning circle) during turning due to centrifugal force. As a result, the central axis α of the hub 2 is inclined with respect to the central axis β of the outer race 1 as shown in an exaggerated manner in FIG.
[0027]
In this state, of the pair of displacement sensor units 26, 26 arranged in the vertical direction, the distance between the thrust detection unit for one displacement sensor unit 26 and the thrust detection surface is reduced, and the displacement of the other displacement sensor unit 26 is reduced. The distance between the thrust detection unit and the thrust detection surface increases. For example, in the case of the example shown in FIG. 4, the distance between the displacement measuring element 27b constituting the thrust detecting portion of the upper displacement sensor unit 26 and one side surface of the bent portion 31, which is the thrust detection surface, increases. On the other hand, the distance between the displacement measuring element 27b of the lower displacement sensor unit 26 and one side surface of the bent portion 31 is reduced. In this case, the amount by which the distance between each of the displacement measuring elements 27b, 27b and one side surface of the bent portion 31 changes increases as the moment load Mx increases.
[0028]
Further, when a moment load is applied in the horizontal direction, that is, a moment load Mz in the direction indicated by Mz in FIG. 5 is applied, and the center axis of the hub 2 and the center axis of the outer ring 1 do not match (in the horizontal direction). In this case, the displacement measuring elements 27b and 27b forming the thrust detecting portions of the two displacement sensor units 26 and 26 arranged in the horizontal direction are connected to one side of the bent portion 31 which is the thrust detection surface. The distance changes.
Further, when a moment load is applied in an oblique direction, the displacement measuring elements 27b, 27b constituting the thrust detecting portions of all (four) displacement sensor units 26, 26 and the above-mentioned bending which is the thrust detection surface The distance between the portion 31 and one side surface changes.
[0029]
Therefore, the detection signals of the displacement measuring elements 27b, 27b constituting the thrust detecting sections of the four displacement sensor units 26, 26 arranged at equal intervals in the circumferential direction (the radial detecting sections are constituted as necessary) By comparing the displacement measuring elements 27a, 27a), it is possible to know the direction in which the moment load acts and the magnitude thereof. Note that the relationship between the amount of change in the distance between the above-described portions and the magnitude of the moment load, and the relationship between the difference between the detection signals of the displacement sensor units 26 and 26 and the direction in which the moment load acts, are also calculated in advance by a formula or a number of formulas. It is determined by experiment or computer analysis.
Also in this case, the relationship between the amount of change in the distance between the above-described portions, the magnitude of the moment load, and the action direction is determined in consideration of the value of the preload applied to the rolling bearing unit for supporting the wheel.
[0030]
Further, when a thrust load is applied to the hub 2 for some reason, the displacement measurement elements 27b, 27b constituting the thrust detection unit and the thrust detection surface are used for all the displacement sensor units 26, 26. The distance between the bent portion 31 and one side surface of the bent portion 31 changes. Then, the direction of the thrust load can be known from the direction of the change (whether it expands or contracts), and the magnitude can be known from the amount of change.
[0031]
During actual traveling, it is rare that a pure radial load, a pure moment load, or a pure thrust load is applied to the hub 2, and these loads are mixed, that is, as shown in FIG. The load Fx, Fy, Fz, Mx, My, and Mz are mixed with each other and are applied to the hub 2 via the tires 33 and the wheels 34. Therefore, the controller determines the type, direction, and magnitude of the load applied to the hub 2 based on a total of eight types of detection signals sent from the respective displacement measuring elements 27a, 27b of the respective displacement sensor units 26, 26. Ask. As described above, the program for obtaining the type, direction, and magnitude of the load from the eight types of detection signals is determined in advance by a calculation formula, a number of experiments, or computer simulations, and is stored in the microcomputer constituting the controller. Install it.
[0032]
In order to improve the accuracy of detecting the displacement in the radial direction, it is preferable to regulate the center of the measuring section of the displacement measuring element 27a constituting the radial detecting section as follows.
That is, when a moment load is applied to the hub 2, on a virtual plane X orthogonal to the center axis of the hub 2 at a point O which is the center of the swing displacement of the hub 2, or with reference to the virtual plane X. The measurement unit is located at a position where the displacement in the axial direction is within 1 to 2 mm. The reason for this is that the displacement based on the moment load hardly affects the detection value of the radial detection unit, and the load in each direction is easily obtained. However, even if the center of the measuring section of the displacement measuring element 27a is displaced by 2 mm or more from the virtual plane X, the displacement amount can be calculated by software installed in the controller. The center position of the part can be determined as appropriate. Further, in order to improve the detection accuracy in the thrust direction, one side of the bent portion 31 constituting the thrust detection portion is shifted by one in the axial direction with respect to the virtual plane X or with respect to the virtual plane X as a reference. It is preferable to locate it in a portion within 2 mm.
[0033]
The relationship between the distances measured by the displacement measuring elements 27a and 27b of the displacement sensor units 26 and 26 and the loads in the respective directions applied to the hub 2 constituting the wheel supporting rolling bearing unit is as follows. It depends on the value of the preload applied to the rolling bearing unit. Specifically, when the value of the preload is large, the rigidity of the rolling bearing unit for supporting the wheel is increased, and as a result, the load applied to the hub 2 in each direction is measured by the displacement measuring elements 27a and 27b. Each of the above distances tends to be small. On the other hand, if the value of the preload is small, the rigidity of the rolling bearing unit for supporting the wheel decreases, and as a result, the load measured in each of the displacement measuring elements 27a and 27b with respect to the load applied to the hub 2 in each direction. Each distance tends to increase.
[0034]
For this reason, in the case of this example, the loads Fx, Fy, Fz, Mx, My, and Mz (FIG. 5) applied to the hub 2 in the respective directions are measured by the displacement measuring elements 27a and 27b. Not only the distance but also the value of the preload given to the wheel supporting rolling bearing unit obtained in advance is taken into consideration (corrected according to the value of the preload) to obtain the value. That is, as described above, in the case of this example, a program to be incorporated in the controller for determining the type, direction, and magnitude of the load applied to the hub 2 is calculated in advance by a calculation formula, a number of experiments, or Determined by computer simulation.
[0035]
Therefore, when determining the program in this way, for each value of the preload applied to the wheel supporting rolling bearing unit, the type, direction, and magnitude of the load applied to the hub 2 and the respective displacement measuring elements 27a, The relationship with each of the distances measured at 27b is similarly obtained by a calculation formula, a number of experiments, or computer simulation, and reflected in the program. At the same time, the value of the preload of the rolling bearing unit for supporting the wheel can be freely input (storable) into the memory constituting the controller as correction data for obtaining the load. Then, the load can be measured in a state where the load is corrected from the distances measured by the displacement measuring elements 27a and 27b during operation according to the value of the preload input to the controller. In order to correct a displacement error of the detected ring 29 with respect to each of the displacement measuring elements 27a and 27b, the hub 2 to which the detected ring 29 is attached is rotated once or a plurality of times. It is also preferable to store the displacement error between the ring 27b and the detected ring 29 in the memory. When the detected error is obtained by rotating the detected ring 29 a plurality of times, the average value is stored in the memory.
[0036]
Further, the value of the preload applied to the wheel supporting rolling bearing unit is determined by various methods known in the art. For example, the rotational torque of the rolling bearing unit for supporting the wheel is measured, the natural frequency is measured, or the tightening amount of the nut 7 for fixing the inner ring 8 so that it cannot be displaced in the axial direction is regulated. To obtain (know) the value of the preload. Then, the value of the preload obtained in this way is input to the memory of the controller at the factory for manufacturing the wheel supporting rolling bearing unit or the automobile assembly factory. When the value of the preload of the rolling bearing unit for supporting the wheel is measured at the manufacturing plant of the rolling bearing unit, and input to the controller at the automobile assembly plant or the like, the value of the preload is bared at the manufacturing plant. The value is attached to each rolling bearing unit by coding. If the value of the preload is bar-coded and attached, the value (preload data) can be easily input at the above-mentioned automobile assembly plant or the like.
[0037]
Further, the value of the preload applied to the rolling bearing unit for supporting the wheel can be obtained in the automobile assembly factory. That is, the preload of the rolling bearing unit may be measured in a state where the wheel supporting rolling bearing unit is mounted on an automobile. Specifically, with the wheel bearing rolling bearing unit assembled to an automobile, an axial load is applied to the hub 2 constituting the rolling bearing unit, and the value of the load and the (axial The value of the preload applied to the rolling bearing unit may be obtained from the relationship with the displacement amount. When the value of the preload is obtained in this manner, it is possible to obtain the preload value in a state where the vehicle body is lifted and the vehicle weight (the weight of the vehicle body) is not applied to the wheel supporting rolling bearing unit. Instead, it is also possible to obtain the rolling bearing unit in consideration of the vehicle weight in a state where the vehicle weight is applied.
[0038]
The above description is based on the case where the displacement sensor units 26, 26 are installed at four equally-spaced positions in the circumferential direction in order to obtain the acting direction and magnitude of the load in each direction applied to the wheel supporting rolling bearing unit. It was shown. In order to obtain the acting direction and magnitude of the load with high accuracy, it is most preferable to provide the four displacement sensor units 26, 26 as described above. However, by reducing the number of each of the displacement sensor units 26, 26, it is possible to achieve cost reduction based on a reduction in the number of parts and the like. For example, as in the second example of the embodiment shown in FIG. 6, the displacement sensors are located at two positions whose phases in the circumferential direction are shifted by 90 degrees, such as the upper end (or lower end) position and the one side position in the horizontal direction. Even when the units 26, 26 are provided, it is possible to obtain the acting direction and magnitude of the load. Further, as in the third example of the embodiment shown in FIG. 7, even when the displacement sensor unit 26 is provided at one position shifted from the vertical direction (or the horizontal direction) by 45 degrees, the load acting direction and It is possible to determine the size.
[0039]
Note that, when a moment load is applied, the displacement in the radial direction and the displacement in the thrust direction cannot be detected independently, so that the processing of the detection signal of the radial detection unit and the detection signal of the thrust detection unit of the displacement sensor unit is somewhat Although it is troublesome, if a structure as shown in FIGS. 8 to 10 is adopted, the work of attaching the displacement sensor unit to the rolling bearing unit can be facilitated. That is, in the case of the structure of the fourth example of the embodiment of the present invention shown in FIGS. 8 to 10, the sensor rotor 3a for detecting the rotational speed is externally fixed to the intermediate portion of the hub 2. . Then, a rotation speed sensor 5a is inserted into a mounting hole 23b formed at one position in the circumferential direction at an axially intermediate portion of the outer ring 1, and a detection surface of the rotation speed detection sensor 5a is changed to an outer peripheral surface of the sensor rotor 3a. To be closely opposed to each other.
[0040]
On the other hand, at the inner end of the inner ring 8 externally fitted and fixed to the inner end of the hub 2, a base end of the detected ring 29a for detecting the displacement in the radial direction and the thrust direction (the left end in FIGS. Part) is externally fitted and fixed. The shape of the detected ring 29a is the same as that of the sensor rotor 3 incorporated in the first example of the embodiment shown in FIG. 1 described above, but the through hole 17 is not provided. Further, the displacement sensor unit 26a is held and fixed to the cover 4 which closes the inner end opening of the outer ring 1. The detection surfaces of the displacement measuring elements 27a and 27b respectively supported at four positions in the circumferential direction of the displacement sensor unit 26a are mounted on the inner circumferential surface or the inner surface of the detected ring 29a in the radial direction or the thrust direction. To be closely opposed to each other.
[0041]
In the case of the structure of the present embodiment as described above, since only one mounting hole 23b provided in the outer ring 1 is required, the work of forming the mounting hole 23b is facilitated, and the cost can be reduced. The strength of the outer ring 1 can be ensured without increasing the wall thickness. Further, when the outer ring 1 and the hub 2 are displaced by loads in each direction, the distance between each of the displacement measuring elements 27a and 27b and the inner peripheral surface or the inner surface of the detected ring 29a changes. Therefore, the direction and magnitude of the load can be determined from the magnitude and direction of the change.
[0042]
In each of the above-described embodiments, the displacement measuring elements 27a and 27b for detecting the displacement in the radial direction or the thrust direction may have various structures known in the art. For example, a magnetic induction type as shown in FIG. 11 or an eddy current type as shown in FIG. 12 can be preferably used. When the magnetic induction type shown in FIG. 11 is used, the material of the detected rings 29 and 29a is a magnetic material such as steel. By passing an exciting current through the first coil 36 wound around the iron core 35, the iron core 35 and the rings to be detected 29 and 29 a are connected to the second coil 37 wound around the iron core 35. The measured value signal according to the distance of the above is supplied. When the eddy current type shown in FIG. 12 is used, the material of the detected rings 29 and 29a may be a magnetic material such as steel, but preferably, a material such as aluminum, copper, brass, or zinc. Non-magnetic metal. Then, an exciting current flows through the coil 39 wound around the ferrite core 38, and the impedance of the coil 39, which changes according to the distance between the ferrite core 38 and the detected rings 29, 29a, is detected.
[0043]
In order to detect the impedance of the coil 39, the change in the impedance is converted into a voltage or a frequency change. As a method of converting into such a voltage or frequency change, an oscillation method, a tuning method, a bridge method, and a positive feedback method are known. For example, in the bridge method among them, as shown in FIG. 13, a bridge circuit 43 is constituted by the coil 39 serving as a detection coil, a reference coil 40, resistors 41 and 41, and a crystal oscillator 42. By measuring the unbalanced voltage, a change in the impedance that changes according to the distance is detected. When such an eddy current type is used, as described above, the material of the detected rings 29 and 29a is a non-magnetic metal such as aluminum, copper, brass, and zinc, and a magnetic material such as steel. Materials can also be used. In short, the best one is selected according to the desired performance and cost.
[0044]
In the case of the eddy current type as described above, for example, those having a sampling rate of 40,000 times / S, a resolution of 0.4 μm, and a measurable distance of about 0 to 2 mm are generally commercially available. . In the case of the present invention, the distance between the displacement measuring elements 27a, 27b for measuring displacement in the radial direction or the thrust direction and the detected rings 29, 29a is set to about 0.5 to 1.5 mm. What is done can be used as it is.
[0045]
When such an eddy current type element is used for the displacement measuring elements 27a and 27b adjacent in the axial direction, the displacement measuring elements 27a and 27b are affected by each other's eddy current, and the measurement is performed. Errors may occur. In order to avoid the influence of such an eddy current, as shown in FIG. 14, a portion of the detected ring 29a between the portions which are in close proximity to the respective displacement measuring elements 27a and 27b, that is, the detected ring An insulating material 44 is provided over the entire circumference of the portion 29a between the radial detection surface and the thrust detection surface. By insulating the surfaces to be detected, the displacement measuring elements 27a and 27b are prevented from being affected by the eddy current.
[0046]
In order to prevent the influence of such eddy current, the current flowing through each of the displacement measuring elements 27a and 27b may be switched and measured. That is, when one of the displacement measuring elements 27a and 27b adjacent in the axial direction performs measurement, the other displacement measuring element 27b (27a) does not perform measurement. Alternatively, the current flowing through each of the displacement measuring elements 27a (27b) may be alternately used. Further, in order to prevent the displacement measuring elements 27a and 27b provided at four positions in the circumferential direction from being affected by the eddy current generated in each of the up, down, left and right directions, the displacement measuring elements at the respective positions are prevented. Switching may be performed for each of the displacement measuring elements 27a and 27b, and the current flowing through each of the displacement measuring elements 27a and 27b may be alternately switched for measurement.
[0047]
Further, in order to prevent the eddy current induced in the detected ring 29a from being released (electrically disseminated) through the detected ring 29a to the inner ring 8 to which the detected ring 29a is fixed, the detected ring is used. 29a may be made of the non-magnetic metal, and the inner ring 8 may be made of steel which is a magnetic metal, or the detected ring 29a may be fixed to the inner ring 8 via an insulating material 44a. . Furthermore, the surface of the inner ring 8 and the surface of the detected ring 29a may be subjected to insulation treatment.
[0048]
As shown in FIG. 5 described above, the hubs 2 (FIGS. 1 and 8) constituting the wheel supporting rolling bearing unit are in a state where the loads Fx, Fy, Fz, Mx, My, and Mz are mixed. Join. Therefore, in the case of the present example, of these loads Fx, Fy, Fz, Mx, My, and Mz, the moment load My applied to the hub 2 around the rotation axis (y axis) is applied to the horizontal Direction from the load Fx and the radius R of the tire 33 fixed to the wheel 34. That is, the moment load My applied to the hub 2 around the rotation axis can be obtained as the product of the horizontal load Fx and the radius R of the tire 33 (My = R · Fx).
[0049]
The radius R of the tire 33 is obtained from the rotational speed of the wheel 34 (the rotational speed of the hub 2) to which the tire 33 is fixed and the speed of the vehicle (vehicle speed). That is, the rotation speed (number of rotations) of the wheel 34 is set to N [min -1 ], And when the speed of the vehicle is V [km / h], V = 120π · R · n. In the case of this example, the rotation speed N is detected by the rotation speed detection sensors 5 and 5a (FIGS. 1 and 8), and the vehicle speed V is measured as follows. That is, as shown schematically in FIG. 15, the vehicle speed V is determined by the image sensor 46 provided below the front side in the traveling direction of the vehicle 45 and the road surface 47 facing the detection surface of the image sensor 46 at regular intervals. It is photographed and calculated from the difference between the images of the road surface 47 obtained from the image sensor 46.
[0050]
Conventionally, when measuring the speed of the vehicle, a speed detecting device utilizing the Doppler effect as described in JP-A-63-64861 and JP-A-63-170157 has been used. That is, the speed of the vehicle is measured by a speed detection device using a phenomenon (Doppler effect) in which the wave of the ultrasonic wave or the laser beam emitted from the vehicle becomes faster (slower) by the speed of the vehicle. On the other hand, in the case of the present example, the speed of the vehicle is measured by the image sensor 46. Specifically, the technology of an optical mouse used as an input device of a computer is used.
[0051]
That is, Japanese Patent Application Laid-Open No. 2000-97639 and U.S. Pat. No. 6,281,882 disclose images of an object obtained at regular intervals by an image sensor (analyze an image shift) to obtain an image of the object. An invention of a displacement measuring device for measuring displacement is described. Then, as a product using such technology, it is incorporated into a mouse for computer input, and the amount of displacement in the vertical and horizontal directions of the mouse is measured (the amount of displacement can be freely converted into a digital signal). A displacement measuring device is actually sold. In the case of the displacement measuring device for a mouse, as shown in FIG. 16, a (infrared) laser beam from a light emitting diode (LED) 53 is passed through a lens 54 to a mouse pad or the like as a target surface (road surface 47 in this example). , And the reflection of the laser light is captured by the image sensor 46 through the lens 55. Then, the displacement of the mouse (the vehicle 45 in this example) is measured by comparing the images captured by the image sensor 46 at 2,300 frames per second.
[0052]
In the case of such a displacement measuring device for a mouse, an image of one frame is composed of pixels of 22 × 22 dots (length × width), and has a resolution of 800 dots per inch, that is, a resolution of about 0.03175 mm per dot. Having. When the speed of the vehicle 45 is obtained as in this example, the resolution of about 0.03175 mm per dot is not necessarily required, considering that the pattern of the road surface 47 is large. Therefore, in the case of this example, the resolution is set to about 3 to 4 mm by changing the focus of a lens provided between the road surface 47 and the image sensor 46. With this configuration, even when the displacement measuring device for a mouse is directly used as the speed measuring device of the vehicle 45, the speed of the vehicle 45 can be measured up to about 200 km / h.
[0053]
When the speed of the vehicle 45 is measured in this manner, the distance between the image sensor 46 and the road surface 47 changes during traveling. Therefore, it is inevitable that the size of the image of the road surface 47 captured by the image sensor 46 changes according to the distance. That is, as the distance between the image sensor 46 and the road surface 47 approaches, the image of the road surface 47 captured by the image sensor 46 increases, and as the distance increases, the image of the road surface 47 decreases. Therefore, the size of the image of the road surface 47 captured by the image sensor 46 is corrected according to the distance between the image sensor 46 and the road surface 47 (so that the images of the road surface 47 having the same size can always be compared). There is a need to.
For this reason, in the case of the present example, a distance measuring sensor 48 for measuring the distance between the image sensor 46 and the road surface 47 is provided, and the distance is measured by the image sensor 46 according to the distance measured by the distance measuring sensor 48. The size of the captured image of the road surface 47 is corrected.
[0054]
As such a distance measuring sensor 48, an optical distance measuring sensor (distance measuring sensor) based on a triangulation method, for example, as described in Japanese Patent Application Laid-Open No. 8-122656 can be used. That is, an (infrared) laser beam is emitted from a light emitting unit such as a light emitting diode toward a target surface (road surface 47), and the reflection of the laser beam is captured by a light receiving unit. The distance between the distance measuring sensor and the target surface is determined from the distance between the light emitting unit and the light receiving unit. In the case of a distance measuring sensor using such a technique, it is inexpensively used as a paper detecting sensor for measuring the size of an original paper by a copying machine. In addition, a device capable of measuring a distance of about 0.2 to 1.5 m with high accuracy, which is required when measuring the distance between the image sensor 46 and the road surface 47 as in this example, is generally commercially available. .
[0055]
Therefore, if the distance between the image sensor 46 and the road surface 47 is measured by such a distance measuring sensor, the speed measuring device of the vehicle 45 can be configured at low cost together with the displacement measuring device for the mouse. In this case, since the light emitting unit (light emitting diode) of the mouse displacement measuring device and the distance measuring device can be shared, it is possible to prevent the size of the speed measuring device from increasing. When such a speed measuring device is attached to the vehicle 45, a cylindrical protective cover 49 as shown in FIG. 17 is provided at each detecting portion of the speed measuring device so that foreign substances such as mud and rainwater are removed during operation. Prevents sticking to the detector. Further, the position at which the speed measuring device is mounted on the vehicle is not limited to the front portion in the traveling direction of the vehicle 45 as shown in FIG. is there.
[0056]
In the case of this example, as described above, the speed (vehicle speed) of the vehicle 45 measured by the above-described speed measuring device and the rotation speed detection sensors 5 and 5a (FIGS. 1 and 8) are used. From the rotation speed of the wheel 34 (= the rotation speed of the hub 2), the radius R (FIG. 5) of the tire 33 fixed to the wheel 34 is obtained. For this reason, when the tire 33 spins (slips) or locks (fixes) on a snowy road, a bad road, or the like, the rotation speed of the wheel 34 measured by the rotation speed detection sensors 5, 5a is extremely higher than the vehicle speed. The value of the radius R of the tire 33 also extremely changes (increases or decreases) accordingly. In such a case, based on the value of the radius R of the tire 33 and the value of the horizontal load Fx applied to the tire 33, the rotation axis (y-axis) applied to the hub 2 constituting the wheel supporting rolling bearing unit ) The moment load My around (My = R · Fx) cannot be obtained accurately.
[0057]
However, an extreme change in the value of the radius R of the tire 33 as described above is unlikely to occur except when the tire 33 bursts (suddenly breaks or ruptures). For this reason, when the value of the radius R of the tire 33 changes extremely in this way, the value, the direction, and the magnitude of the load applied to the hub 2 obtained by the above-described displacement measuring elements 27a and 27b are determined. Then, it is determined whether the tire 33 spins, locks or bursts.
If it is determined that the tire 33 has been spinned and locked, the moment load My is calculated based on the value of the radius R of the tire 33 previously stored (stored) in the memory of the controller. (My = R · Fx) is obtained. It is preferable that the value of the radius R of the tire 33 stored in the memory of the controller be corrected (re-measured) at predetermined intervals. (Although the value hardly changes unless the air of the tire 33 leaks or the load weight changes largely,) By correcting the value of the radius R of the tire 33 at predetermined intervals in this manner, the value stored in the memory is obtained. And the actual value are greatly different.
[0058]
Further, based on the radius R of the tire 33 obtained as described above and the type, direction and magnitude of the load applied to the hub 2 obtained by the above-described displacement measuring elements 27a and 27b, the air pressure of the tire 33 is determined. The amount of reduction or deformation can also be estimated.
For example, from the value of the radius R of the tire 33 and the vertical load Fz applied to the hub 2 (see FIG. 5), or the value of the radius R of the tire 33 stored in the memory and the actual measurement value , It can be determined whether or not the air in the tire 33 has leaked (decreased). Then, when it is determined that the air pressure of the tire 33 has decreased, the driver is informed that the air pressure has decreased, and the driver is prompted to supply air to the tire 33. As a result, it is possible to prevent the vehicle from traveling in a state where the air pressure is reduced, and it is possible to prevent the vehicle 45 from traveling in an unstable manner or to easily burst when the tire 33 undulates (due to a standing wave) during high-speed traveling. Can be prevented. If the amount of decrease or deformation of the radius R of the tire 33 is sharp, the driver is informed of the danger by a warning sound or the like, and stop running, replenish the air, and further replace the tire 33. Prompt.
[0059]
In the case of this example as described above, the type, direction and magnitude of the load applied to the hub 2 constituting the wheel supporting rolling bearing unit as described above are determined by the preload applied to the wheel supporting rolling bearing unit. Is determined with higher accuracy in consideration of the value of. At the same time, the speed of the vehicle 45 and the radius R of the tire 33 can be obtained with higher accuracy without increasing the cost of the measuring device. For this reason, control of ABS, TCS, VSC, etc. can be performed highly and appropriately.
[0060]
For example, ABS, TCS, and VSC technologies are described in "Automotive Technology Basic Course-15th" of the magazine "Automotive Technology" (Vol. 54, No. 6, 2000). In the case of the ABS, the brake pressure is controlled so as to have a predetermined slip ratio {(vehicle speed-wheel rotation speed) / vehicle speed}, thereby decelerating the vehicle while preventing tire locking. The technology is described. In the case of this example, the speed of the vehicle 45 and the rotation speed of the wheels 44 can be measured with high accuracy as described above, so that the slip ratio can be accurately obtained. At the same time, the horizontal load Fx (FIG. 5) applied to the hub 2, which is obtained as a braking force when the vehicle is decelerated, is also required to be obtained with high accuracy, so that the brake for setting the slip ratio to a predetermined value is used. The control of the pressure can be performed in an advanced and proper manner. Also, in the case of controlling the above TCS and VSC, if various loads Fx, Fy, Fz, Mx, My, Mz (FIG. 5) applied to the hub 2 can be obtained with high accuracy as in this example, Vehicle control can be performed at a high level.
[0061]
Japanese Patent Application Laid-Open No. Hei 3-220056 discloses that the frictional force between a tire and a road surface is detected, and the brake pressure is increased while the frictional force is increased, thereby decelerating the vehicle while preventing the tire from being locked. The invention of an anti-lock brake device is described. As shown in FIG. 18, a frictional force μ between the tire 33 and the road surface 47 is applied to the hub 2 as a reaction force thereof as a horizontal load Fx. Therefore, in the case of the present example in which the load Fx is obtained with high accuracy, the above-described vehicle control can be performed with higher dimensions.
[0062]
Also, Japanese Patent Application Laid-Open No. H11-255091 describes an invention of an ABS device that performs optimal control using a load of each direction obtained from a load sensor using an algorithm of a neural network (artificial intelligence). Also in the case of the invention described in this publication, higher-dimensional control can be performed if each load applied to the hub 2 can be obtained with high accuracy as in the present embodiment.
[0063]
Next, FIGS. 19 and 20 show a fifth example of the embodiment of the present invention. In the case of this example, of the displacement measuring elements 27a and 27b for detecting the displacements in the radial direction and the thrust direction, the displacement measuring element 27a for detecting the displacement in the radial direction is used. Can also be detected. That is, in the case of this example, a part of the part of the detection target cylindrical portion 50 constituting the detection target ring 29b, which is close to and opposed to the displacement measuring element 27a for detecting the displacement in the radial direction, functions as a thinning part. A large number of through holes 51 are formed at regular intervals in the circumferential direction. Each of the through holes 51 has a slit shape that is long in the axial direction. The portion between the through holes 51 adjacent to each other in the circumferential direction is a pillar portion functioning as a solid portion.
[0064]
When the detected ring 29b having the through holes 51 is rotated, the output of the displacement measuring element 27a (after the waveform shaping process) changes as shown by a solid line α in FIG. That is, when each of the through holes 51, 51 of the detection target cylindrical portion 50 and the displacement measuring element 27a are opposed to each other, the output of the displacement measuring element 27a is reduced. The output of the displacement measuring element 27a increases when facing each column, which is an intervening portion. Since the frequency at which the output of the displacement measuring element 27a changes is proportional to the rotation speed of the wheel, the rotation speed of the wheel can be obtained by inputting an output signal to a controller (not shown) through the harness. The distance between the displacement measuring element 27a for detecting the displacement in the radial direction and the inner peripheral surface of the ring to be detected 29b is the distance between the through holes 51 in the cylindrical portion 50 for detection. Can be obtained from the magnitude of the output of the displacement measuring element 27a when each of the column portions faces the displacement measuring element 27a.
[0065]
In the case of this example configured as described above, there is no need to provide the outer ring 1 with the mounting hole 23b for mounting the rotation speed detection sensor 5a (see FIG. 8). Therefore, the working of the outer ring 1 is facilitated to reduce the cost, and the strength of the outer ring 1 can be ensured without increasing the thickness of the outer ring 1 in particular. In addition, since the harness between the rotation speed detection sensor 5a provided on the outer ring 1 and the controller can be omitted, the harness can be easily handled, and the wheel supporting rolling bearing unit with the load measuring device can be assembled to the suspension device. Work can be facilitated. The configuration and operation of the other parts are the same as in the case of the above-described fourth example.
[0066]
Next, FIGS. 22 to 23 show a sixth example of the embodiment of the present invention. In the case of this example, a rotational speed detection sensor 5b for measuring the rotational speed of the hub 2 is provided in a displacement sensor unit 26b for measuring the radial and thrust displacements of the hub 2 with respect to the outer ring 1. That is, the rotation speed detection sensor 5b is mounted in the displacement sensor unit 26b, which is fixed to the cover 4 covering the inner end opening of the outer ring 1 and includes the displacement measuring elements 27a and 27b in a synthetic resin. The rotation speed detecting element 52 that is configured also supports the envelope.
[0067]
As shown in FIG. 22, the rotational speed detecting element 52 is provided in the displacement sensor unit 26b at a portion deviated in the axial direction from each of the displacement measuring elements 27a and 27b, or as shown in FIG. It is located in a portion between the displacement measuring elements 27a and 27b adjacent in the direction. As such a rotational speed detecting element 52, various structures can be used in the same manner as the displacement measuring elements 27a and 27b, but in the case of this example, the eddy current similar to the variable measuring elements 27a and 27b is used. It is of the formula. On the other hand, a large number of through-holes 51 are formed at a portion near the axial inner end of the detection target cylindrical portion 50 constituting the detection target ring 29c and at a position close to and opposed to the rotation speed detection element 52 at equal intervals in the circumferential direction. Has formed. Then, as in the case of the fifth example of the above-described embodiment, the rotation speed is detected from the change in the output of the rotation speed detection element 52.
[0068]
When a ring made of a magnetic metal plate such as a steel plate is used as the detected ring 29c, the rotational speed detecting element 52 is a magnetic detecting element that changes its characteristic according to the amount of magnetic flux passing through a Hall element, an MR element, or the like. Elements can also be used. When such a magnetic detecting element is used, the magnetic characteristics of a portion of the cylindrical portion 50 to be detected, which constitutes the detected ring 29c, near the inner end in the axial direction, and which is close to and opposed to the rotational speed detecting element 52, are determined. , And alternately (generally at regular intervals) in the circumferential direction.
[0069]
In order to alternately change the magnetic characteristics in the circumferential direction in this way, a large number of thinned portions and solid portions are alternately formed in the circumferential direction, or the S pole and the N pole are alternately formed. The placed permanent magnet is attached. In the former case, a large number of through-holes 51 are formed in a portion of the detection target cylindrical portion 50 constituting the detection target ring 29c at a portion near the inner end in the axial direction and in proximity to the rotation speed detection element 52, in the circumferential direction. Are formed at equal intervals. In this case, a permanent magnet magnetized in the radial direction of the detected ring 29c is incorporated in the rotation speed detection sensor 5b. Alternatively, instead of forming such a through-hole 51, an S-pole and an N-pole are alternately arranged in the circumferential direction on the inner peripheral surface of the portion to be detected near the inner end in the axial direction. In addition, permanent magnets (magnetized) arranged at equal intervals are attached.
In this case, the permanent magnet on the rotation speed detection sensor 5b side is unnecessary.
[0070]
When the detected ring 29c whose magnetic characteristics are changed alternately and at equal intervals in the circumferential direction as described above rotates, the portion near the rotation speed detecting element 52, which is the magnetic detecting element, is moved through the transparent part. The holes 51 and the pillars located between the through holes 51 or the S pole and the N pole pass alternately. As a result, the amount of magnetic flux (or the direction of the magnetic flux) flowing in the rotation speed detection element 52 changes, and the output of the rotation speed detection sensor 5b incorporating the rotation speed detection element 52 changes. Since the frequency at which this output changes is proportional to the rotation speed of the wheel, the rotation speed of the wheel can be obtained by inputting an output signal to the controller through the harness. The configuration and operation of the other parts are the same as in the case of the fifth example described above.
[0071]
Next, FIG. 24 shows a seventh example of the embodiment of the present invention. In each of the above-described embodiments, the stationary raceway which supports and fixes the outer race 1 (for example, see FIG. 1) radially outside of the rolling elements 10 and 10 to the suspension device in use is used. The hub 2 (see, for example, FIG. 1), which also exists inside in the radial direction, is a rotating raceway that supports and fixes the wheel in use. On the other hand, in the case of this example, the wheels are supported and fixed in use in a radially outer side of a pair of inner rings 8, 8 which are stationary raceways, which are externally fitted and fixed to a support shaft (not shown) in use. The hub 2a is rotatably supported via a plurality of rolling elements 10, 10.
[0072]
Also, a displacement sensor unit 26c formed by embedding displacement measuring elements 27a and 27b in a synthetic resin is provided on the outer peripheral surface of the inner end of the inner ring 8 that is located on the inner side in the axial direction of the pair of inner rings 8 and 8. I support it. Then, of the displacement measuring elements 27a and 27b, the displacement measuring element 27a for detecting the displacement in the radial direction is brought directly close to the outer peripheral surface of the inner end portion of the hub 2a (not through the detected ring). At the same time, a displacement measuring element 27b for detecting a displacement in the thrust direction is also directly opposed to the inner end face of the hub 2a (without a detected ring). The configuration and operation of the other parts are the same as in the case of the above-described sixth example.
[0073]
【The invention's effect】
Since the rolling bearing unit for supporting a wheel with a load measuring device of the present invention is configured and operates as described above, the direction and magnitude of the load applied to the wheels during traveling can be measured, and the factors that impair the traveling stability of the vehicle. Can be detected in advance, and it is possible to respond to this, which can contribute to the safe operation of the vehicle. In addition, since the number of components is small and it is not necessary to use heavy components, the above measurement can be performed with high accuracy without suppressing unsprung load and deteriorating running performance mainly in ride comfort. .
[Brief description of the drawings]
FIG. 1 is a sectional view showing a first example of an embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view taken along the line AA of FIG. 1, showing the installation state of the displacement sensor unit, with a part thereof being omitted;
FIG. 3 is a diagram corresponding to a portion B in FIG. 1 and shows a state in which both the radial and thrust detection sections face the radial and thrust detection surfaces.
FIG. 4 is an exaggerated cross-sectional view showing a state where the rotation center of the hub is inclined based on a moment load.
FIG. 5 is a perspective view schematically showing a load applied to a hub via a tire and wheels.
FIG. 6 is a sectional view similar to FIG. 2, showing a second example of the embodiment of the present invention;
FIG. 7 is a sectional view similar to FIG. 2, showing the third example;
FIG. 8 is a sectional view showing the fourth example.
FIG. 9 is an enlarged view of a portion C in FIG. 8;
FIG. 10 is a diagram illustrating a detected ring and a displacement measuring element of a displacement sensor unit taken out from the right side of FIG. 8;
FIG. 11 is a perspective view showing the principle of a magnetic induction type displacement measuring element.
FIG. 12 is a perspective view showing the principle of an eddy current type displacement measuring element.
FIG. 13 is a diagram showing a circuit (bridge method) for converting the impedance of a coil constituting an eddy current type displacement measuring element.
FIG. 14 is a sectional view similar to FIG. 9, showing a modification of the fourth example of the embodiment of the present invention;
FIG. 15 is a schematic view showing an attached state of a vehicle speed measuring device.
FIG. 16 is a schematic diagram for explaining the structure of a vehicle speed measuring device.
FIG. 17 is a perspective view showing a protective cover attached to a sensor of the vehicle speed measuring device.
FIG. 18 is a side view schematically showing a load in a horizontal direction (traveling direction) applied to a wheel via a tire.
FIG. 19 is a sectional view showing a fifth example of the embodiment of the present invention.
FIG. 20 is an enlarged view of a portion D in FIG. 18;
FIG. 21 is a diagram showing an output change of a displacement measuring element.
FIG. 22 is a partial sectional view showing a sixth example of the embodiment of the present invention.
FIG. 23 is a view similar to FIG. 10, but showing a part of the installation state of the displacement sensor unit;
FIG. 24 is a half sectional view showing a seventh example of the embodiment of the present invention.
FIG. 25 is a sectional view showing a first example of a conventional structure.
FIG. 26 is a sectional view showing the second example.
[Explanation of symbols]
1 outer ring
2, 2a hub
3, 3a Sensor rotor
4 Cover
5, 5a, 5b Rotation speed detection sensor
6 Outer ring track
7 nuts
8 Inner ring
9 Inner ring track
10 rolling elements
11 cage
12 Flange
13 Mounting part
14 Seal ring
15 Cylindrical part for detection
16 Supporting cylinder
17 Through-hole
18 Fitting tube
19 closing plate
20 through holes
21 Connector
22 studs
23, 23a, 23b Mounting holes
24 Displacement sensor
25 Sensor ring
26, 26a, 26b, 26c Displacement sensor unit
27a, 27b displacement measuring element
28 Holder
29, 29a, 29b Detected ring
30 cylindrical part
31 Bent part
32 harness
33 tires
34 wheels
35 iron core
36 First coil
37 Second coil
38 Ferrite core
39 coils
40 Reference coil
41 Resistance
42 crystal oscillator
43 Bridge circuit
44, 44a Insulating material
45 vehicle
46 Image Sensor
47 Road surface
48 Distance measuring sensor
49 Protective cover
50 Cylindrical part for detection
51 Through-hole
52 Rotation speed detection element
53 light emitting diode
54 lenses
55 lenses

Claims (3)

車輪支持用転がり軸受ユニットと荷重測定装置とを備え、
このうちの車輪支持用転がり軸受ユニットは、使用状態で懸架装置に支持固定される静止側軌道輪と、使用状態で車輪を支持固定する回転側軌道輪と、これら静止側軌道輪と回転側軌道輪との互いに対向する周面に存在する静止側軌道と回転側軌道との間に設けられた複数個の転動体とを備えたものであり、
上記荷重測定装置は、上記回転側軌道輪の回転中心と同心に設けられた円筒状のラジアル被検出面及びこの回転側軌道輪の回転中心に対し直角方向に設けられたスラスト被検出面と、上記静止側軌道輪に設けられた少なくとも１個の変位センサユニットとから成り、この変位センサユニットはラジアル検出部とスラスト検出部とを備え、このうちのラジアル検出部と上記ラジアル被検出面との距離、並びにスラスト検出部と上記スラスト被検出面との距離を測定自在なものであり、上記変位センサユニットから測定されるこれら各距離と、予め求めた上記車輪支持用転がり軸受ユニットに付与された予圧の値とから、上記回転側軌道輪に加わる荷重を求める、
荷重測定装置付車輪支持用転がり軸受ユニット。Equipped with a rolling bearing unit for wheel support and a load measuring device,
The rolling bearing unit for supporting the wheel includes a stationary raceway supported and fixed to the suspension device in use, a rotating raceway supporting and fixing the wheel in use, and a stationary raceway and a rotating raceway. A plurality of rolling elements provided between the stationary-side orbit and the rotating-side orbit present on the peripheral surfaces of the wheels facing each other,
The load measuring device includes a cylindrical radial detection surface provided concentrically with the rotation center of the rotating raceway and a thrust detection surface provided in a direction perpendicular to the rotation center of the rotation raceway, And at least one displacement sensor unit provided on the stationary raceway. The displacement sensor unit includes a radial detection unit and a thrust detection unit. The displacement detection unit includes a radial detection unit and a thrust detection surface. The distance, and the distance between the thrust detection unit and the thrust detection surface can be freely measured, and these distances measured from the displacement sensor unit and the wheel support rolling bearing unit obtained in advance are provided. From the value of the preload, determine the load applied to the rotating raceway ring,
Rolling bearing unit for wheel support with load measuring device. 車輪支持用転がり軸受ユニットを自動車に組み付けた状態で、回転側軌道輪に軸方向の荷重を加え、この荷重の値とこの回転側軌道輪の変位量とから上記車輪支持用転がり軸受ユニットに付与された予圧の値を求める、請求項１に記載した荷重測定装置付車輪支持用転がり軸受ユニット。An axial load is applied to the rotating raceway ring in a state where the wheel supporting rolling bearing unit is assembled to the vehicle, and the wheel supporting rolling bearing unit is applied to the wheel supporting rolling bearing unit from the value of the load and the displacement amount of the rotating raceway ring. The rolling bearing unit for supporting a wheel with a load measuring device according to claim 1, wherein the value of the preload obtained is obtained. 回転側軌道輪に加わる回転軸回りのモーメント荷重を、この回転側軌道輪に加わる水平方向の荷重と車輪に固定されたタイヤの半径とから求める、請求項１〜２の何れかに記載した荷重測定装置付車輪支持用転がり軸受ユニット。The load according to any one of claims 1 to 2, wherein a moment load around the rotating shaft applied to the rotating race is obtained from a horizontal load applied to the rotating race and a radius of a tire fixed to the wheel. Rolling bearing unit for wheel support with measuring device.
JP2002203072A 2002-07-11 2002-07-11 Rolling bearing unit for wheel support with load measuring device Expired - Fee Related JP3900031B2 (en)

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US8700270B2 (en) 2011-07-11 2014-04-15 Cnh America Llc System and method for determining drawbar force magnitude and direction
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