JP2013019427A - Bearing unit - Google Patents

Bearing unit Download PDF

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JP2013019427A
JP2013019427A JP2011150557A JP2011150557A JP2013019427A JP 2013019427 A JP2013019427 A JP 2013019427A JP 2011150557 A JP2011150557 A JP 2011150557A JP 2011150557 A JP2011150557 A JP 2011150557A JP 2013019427 A JP2013019427 A JP 2013019427A
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Prior art keywords
bearing
press
pressure
ring
fitting
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JP2011150557A
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Japanese (ja)
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Junya Inoyae
順也 猪八重
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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
    • 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
    • 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

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

Abstract

PROBLEM TO BE SOLVED: To provide a low-cost bearing unit in which changes in the pressure (inner pressure) in a bearing inner space associated with changes in the bearing temperature is easily alleviated, even when using an existing bearing configuration as it is.SOLUTION: The bearing unit includes sealing members 10a to 10c for sealing a bearing inner space segmented between bearing rings 2, 4. The volume of the bearing inner space under the condition of press-fitting and fixing both sealing members into the bearing rings is denoted by VB; and the volume of the bearing inner space, which is decreased by a volume corresponding to a press-fitting stroke dimension under the condition that while one sealing member is press-fitted and fixed to the bearing ring, the other sealing member is press-fitted into the bearing ring, is denoted by VC. The press-fitting stroke dimension to press-fit the other sealing member into the bearing ring is adjusted to obtain such a ratio of VB to VC that neither the pressure of the bearing inner space reaches a negative pressure at a lower limit of assumed temperature of the bearing, nor the pressure of the bearing inner space exceeds a leakage limit of the sealing member at an upper limit of the assumed temperature of the bearing.

Description

本発明は、例えば自動車の車輪を懸架装置に対して回転自在に支持するために用いられる軸受ユニットに関する。   The present invention relates to a bearing unit used, for example, for rotatably supporting a wheel of an automobile with respect to a suspension device.

従来、自動車の車輪側構成品（例えば、ディスクホイール）を車体側構成品（例えば、懸架装置（ナックル））に対して回転自在に支持するための各種の軸受ユニットが知られている（例えば、特許文献１参照）。その一例として、図２(ａ)には、従動輪用の軸受ユニットが示されている。   2. Description of the Related Art Conventionally, various bearing units for supporting a vehicle wheel side component (for example, a disc wheel) rotatably with respect to a vehicle body side component (for example, a suspension device (knuckle)) are known (for example, Patent Document 1). As an example, FIG. 2 (a) shows a bearing unit for a driven wheel.

従動輪用の軸受ユニットは、車体側構成品に固定されて常時非回転状態に維持される一方の軌道輪（例えば、静止輪（外輪））２と、静止輪（外輪）２の内側に対向して配置され、かつ、車輪側構成品に接続されて車輪と共に回転する他方の軌道輪（例えば、回転輪（内輪））４と、相対回転する静止輪２と回転輪４との間に複列（例えば、２列）で回転可能に組み込まれた複数の転動体６,８とを備えている。なお、転動体６,８として、図面では「玉」を例示しているが、軸受ユニットの使用目的や使用環境に応じて「ころ」が適用される場合もある。   The bearing unit for the driven wheel is fixed to the vehicle body side component and is opposed to the inner side of one of the track rings (for example, the stationary ring (outer ring) 2) and the stationary ring (outer ring) 2 that are always maintained in a non-rotating state. Between the other bearing ring (for example, the rotating wheel (inner ring)) 4 connected to the wheel-side component and rotating together with the wheel, and the stationary wheel 2 and the rotating wheel 4 rotating relative to each other. And a plurality of rolling elements 6 and 8 that are rotatably incorporated in a row (for example, two rows). In addition, as the rolling elements 6 and 8, “balls” are illustrated in the drawings, but “rollers” may be applied depending on the purpose and environment of use of the bearing unit.

静止輪（外輪）２は中空円筒状を成しており、回転輪（内輪）４の外周を覆うように配置されている。この場合、静止輪２と回転輪４との間には、軸受ユニットの内部（即ち、静止輪２と回転輪４との間で区画された環状の軸受内部空間）を、その軸方向両側から密封するためのシール部材（車輪側のリップシール１０ａ、車体側のカバー１０ｂ）が設けられている。   The stationary ring (outer ring) 2 has a hollow cylindrical shape and is arranged so as to cover the outer periphery of the rotating ring (inner ring) 4. In this case, between the stationary wheel 2 and the rotating wheel 4, the inside of the bearing unit (that is, the annular bearing inner space defined between the stationary wheel 2 and the rotating wheel 4) from both sides in the axial direction. Sealing members (wheel side lip seal 10a, vehicle body side cover 10b) for sealing are provided.

リップシール１０ａは、静止輪（外輪）２の内周面２ｎにおいて車輪側端部に構成された固定面２ｎ-1に圧入させて固定され、かつ、回転輪（内輪）４の外周面４ｍにおいて車輪側に構成された摺動面４ｎ-1に対して摺動自在に位置決めされている。一方、カバー１０ｂは、上記した軸受内部空間全体を車体側から覆うように、静止輪（外輪）２の内周面２ｎにおいて車体側端部に構成された固定面２ｎ-2に圧入させて固定されている。   The lip seal 10 a is fixed by being press-fitted into a fixed surface 2 n-1 formed at the wheel side end portion on the inner peripheral surface 2 n of the stationary wheel (outer ring) 2, and on the outer peripheral surface 4 m of the rotating wheel (inner ring) 4. It is slidably positioned with respect to the sliding surface 4n-1 constructed on the wheel side. On the other hand, the cover 10b is fixed by being press-fitted into a fixed surface 2n-2 formed at the end of the vehicle body on the inner peripheral surface 2n of the stationary wheel (outer ring) 2 so as to cover the entire bearing inner space from the vehicle body side. Has been.

また、静止輪（外輪）２には、その外周面２ｍから外方に向って放射状に突出した固定フランジ２ａが一体成形されている。この場合、固定フランジ２ａの各固定孔２ｂに固定用ボルト（図示しない）を挿入し、これらを車体側構成品に締結することで、静止輪（外輪）２を例えばナックル（図示しない）に固定することができる。   The stationary ring (outer ring) 2 is integrally formed with a fixing flange 2a that protrudes radially outward from the outer peripheral surface 2m. In this case, a stationary bolt (outer ring) 2 is fixed to, for example, a knuckle (not shown) by inserting a fixing bolt (not shown) into each fixing hole 2b of the fixing flange 2a and fastening them to a vehicle body side component. can do.

一方、回転輪（内輪）４には、車輪側構成品を支持しつつ共に回転し、かつ、円筒形状を成す中実のハブ１２が設けられており、ハブ１２には、例えばディスクホイール（図示しない）が固定されるハブフランジ１２ａが突設されている。ハブフランジ１２ａは、静止輪（外輪）２を越えて外方（ハブ１２の径方向外側）に向って放射状に延出しており、その延出縁付近には、周方向に沿って所定間隔で配置された複数のハブボルト１４が設けられている。   On the other hand, the rotating wheel (inner ring) 4 is provided with a solid hub 12 that rotates while supporting the wheel-side components and has a cylindrical shape. The hub flange 12a is fixedly projected. The hub flange 12a extends radially outward (outward in the radial direction of the hub 12) beyond the stationary ring (outer ring) 2, and in the vicinity of the extended edge at a predetermined interval along the circumferential direction. A plurality of arranged hub bolts 14 are provided.

ここで、複数のハブボルト１４を例えばディスクホイールに形成された各ボルト孔（図示しない）に差し込んで、ハブナット（図示しない）で締付けることにより、当該ディスクホイールをハブフランジ１２ａに対して位置決めして固定することができる。なお、このとき、ハブ１２の車輪側に突設されたパイロット部１２ｄによって車輪側構成品の径方向の位置決めが成される。   Here, by inserting a plurality of hub bolts 14 into respective bolt holes (not shown) formed in the disc wheel and tightening with hub nuts (not shown), the disc wheel is positioned and fixed with respect to the hub flange 12a. can do. At this time, the radial positioning of the wheel-side component is performed by the pilot portion 12d protruding from the wheel side of the hub 12.

また、ハブ１２には、その外周面４ｍにおいて車体側端部に嵌合面４ｎ-2が構成されており、当該嵌合面４ｎ-2に環状の回転輪構成体１６（ハブ１２と共に回転輪（内輪）４を構成する部材）を嵌合（圧入）させることができるようになっている。この場合、例えば、静止輪２と回転輪４との間に各転動体６,８を保持器１８で保持した状態で、回転輪構成体１６を嵌合面４ｎ-2に形成された段部１２ｂまで嵌合した後、ハブ１２の車体側端部の加締め領域１２ｃを塑性変形させて、当該加締め領域１２ｃを回転輪構成体１６の周端部１６ｓに沿って加締める（密着させる）ことで、当該回転輪構成体１６をハブ１２に固定することができる。   The hub 12 has a fitting surface 4n-2 at the vehicle body side end portion on the outer peripheral surface 4m. The fitting surface 4n-2 has an annular rotating wheel structure 16 (a rotating wheel together with the hub 12). (Members constituting the inner ring) 4) can be fitted (press-fitted). In this case, for example, in a state where the rolling elements 6 and 8 are held by the cage 18 between the stationary wheel 2 and the rotating wheel 4, the rotating wheel component 16 is formed on the fitting surface 4n-2. After fitting up to 12b, the caulking region 12c at the end of the hub 12 on the vehicle body side is plastically deformed, and the caulking region 12c is caulked (closely adhered) along the peripheral end 16s of the rotating wheel constituting body 16. Thus, the rotating wheel component 16 can be fixed to the hub 12.

このとき、軸受ユニットには所定の予圧が付与された状態となり、この状態において、各転動体６,８は、互いに所定の接触角を成して静止輪２と回転輪４の各軌道溝（静止軌道溝２ｓ、回転軌道溝４ｓ）にそれぞれ接触して回転可能に組み込まれる。この場合、２つの接触点を結んだ作用線（図示しない）は、各軌道溝２ｓ,４ｓに直交し、かつ、各転動体６,８の中心を通り、軸受ユニットの中心線上の１点（作用点）で交わる。これにより背面組合せ形（ＤＢ）軸受が構成される。   At this time, a predetermined preload is applied to the bearing unit, and in this state, the rolling elements 6 and 8 form a predetermined contact angle with each other and each raceway groove ( The stationary raceway groove 2s and the rotary raceway groove 4s) are in contact with each other and are rotatably incorporated. In this case, an action line (not shown) connecting the two contact points is orthogonal to the raceway grooves 2s and 4s, passes through the centers of the rolling elements 6 and 8, and is on one point on the center line of the bearing unit ( At the point of action). This constitutes a rear combination (DB) bearing.

このような軸受構成において、自動車走行中に車輪に作用した力は、全てディスクホイールから軸受ユニットを通じてナックルに伝達されることになり、その際、軸受ユニットには、各種の荷重（ラジアル荷重、アキシアル荷重、モーメント荷重など）が作用する。しかし、軸受ユニットは、上述したような背面組合せ形（ＤＢ）軸受となっているため、各種の荷重に対して高い剛性が維持される。   In such a bearing configuration, all of the force acting on the wheel while the vehicle is running is transmitted from the disc wheel to the knuckle through the bearing unit. At this time, various loads (radial load, axial load) are applied to the bearing unit. Load, moment load, etc.). However, since the bearing unit is a back combination (DB) bearing as described above, high rigidity is maintained against various loads.

一方、例えば図２(ｂ)には、駆動輪用の軸受ユニットが示されており、当該軸受ユニットでは、軸受内部空間を密封するためのシール部材として、上記した車体側のカバー１０ｂに代えてパックシール１０ｃが設けられている。特に参照符号は付さないが、パックシール１０ｃは、相対的に摺動自在に対向したシール片とスリンガとを有しており、車体側からパックシール１０ｃを圧入することで、シール片が静止輪（外輪）２の内周面２ｎにおいて車体側端部に構成された固定面２ｎ-2に固定されると共に、スリンガが回転輪４の外周面４ｍにおいて車体側端部（具体的には、車体側端部の嵌合面４ｎ-2に加締め固定された回転輪構成体１６の外周）に構成された固定面１６ｎに固定される。   On the other hand, for example, FIG. 2B shows a drive wheel bearing unit. In the bearing unit, instead of the above-described cover 10b on the vehicle body side as a seal member for sealing the bearing internal space. A pack seal 10c is provided. The pack seal 10c has a seal piece and a slinger that are relatively slidably opposed to each other, but the seal piece is stationary by press-fitting the pack seal 10c from the vehicle body side. The slinger is fixed to the fixed surface 2n-2 formed at the vehicle body side end portion on the inner peripheral surface 2n of the ring (outer ring) 2 and the slinger is positioned on the vehicle body side end portion (specifically, It is fixed to a fixed surface 16n configured on the outer periphery of the rotating wheel component 16 fixed by caulking to the fitting surface 4n-2 at the vehicle body side end.

また、駆動輪用の軸受ユニットにおいて、ハブ１２（回転輪４）は、中空円筒状を成しており、図示しない等速ジョイント（ＣＶＪ）が連結されるようになっている。具体的に説明すると、ハブ１２（回転輪４）の内周には、１本のスプライン孔１２ｈが回転軸方向に沿って貫通して形成されている。この場合、等速ジョイントのスプライン軸（図示しない）を回転輪４（ハブ１２）のスプライン孔１２ｈに挿入し、等速ジョイントの外輪（図示しない）を回転輪４（ハブ１２の加締め領域１２ｃ）に当接させると共に、当該スプライン軸の挿入先端をナット（図示しない）でパイロット部１２ｄに固定させることで、当該軸受ユニットと等速ジョイントとを相互に連結させることができる。   In the drive wheel bearing unit, the hub 12 (the rotating wheel 4) has a hollow cylindrical shape and is connected to a constant velocity joint (CVJ) (not shown). More specifically, a single spline hole 12h is formed through the inner periphery of the hub 12 (rotating wheel 4) along the direction of the rotation axis. In this case, the spline shaft (not shown) of the constant velocity joint is inserted into the spline hole 12h of the rotating wheel 4 (hub 12), and the outer ring (not shown) of the constant velocity joint is inserted into the rotating wheel 4 (caulking region 12c of the hub 12). In addition, the bearing unit and the constant velocity joint can be connected to each other by fixing the insertion tip of the spline shaft to the pilot portion 12d with a nut (not shown).

かかる構成において、例えばドライブシャフトの角度の変化に対応して等速ジョイントが自由に角度変化することで、所定トルクの駆動力が軸受ユニットを介してディスクホイールに等速かつ円滑に伝達されることになる。なお、他の構成は、上記した従動輪用の軸受ユニット（図２(ａ)）と同一であるため、図２(ｂ)において同一符号を付して、その説明を省略する。   In such a configuration, for example, the constant velocity joint freely changes its angle in response to a change in the angle of the drive shaft, so that a driving force of a predetermined torque is transmitted to the disc wheel through the bearing unit at a constant speed and smoothly. become. Since the other configuration is the same as the bearing unit for the driven wheel (FIG. 2A), the same reference numerals are given in FIG. 2B, and the description thereof is omitted.

特開２００５−２５６８９７号公報JP 2005-256897 A 特開２００９−１２７６６０号公報JP 2009-127660 A 特開２０１０−３８２５０号公報JP 2010-38250 A

ところで、上記した従動輪用及び駆動輪用の軸受ユニット（図２(ａ),(ｂ)）の組立では、まず、静止輪（外輪）２に、車輪側のリップシール１０ａと各転動体６,８と保持器１８とを組み付けてユニット化させたサブアセンブリ（サブアッシーともいう）を構成する。次に、サブアセンブリをハブ１２に被せた後（換言すると、サブアセンブリにハブ１２を挿入した後）、静止輪（外輪）２と回転輪４（ハブ１２）との間に区画された軸受内部空間に、潤滑剤（例えば、グリース、油）を封入する。   By the way, in the assembly of the bearing unit for the driven wheel and the driving wheel (FIGS. 2A and 2B), first, the lip seal 10a on the wheel side and each rolling element 6 are attached to the stationary wheel (outer ring) 2. , 8 and the retainer 18 are assembled to form a subassembly (also referred to as subassembly). Next, after the subassembly is put on the hub 12 (in other words, after the hub 12 is inserted into the subassembly), the inside of the bearing defined between the stationary ring (outer ring) 2 and the rotating ring 4 (hub 12). A lubricant (for example, grease or oil) is sealed in the space.

そして、回転輪構成体１６を圧入し、加締め領域１２ｃを加締めた後、図１(ａ),(ｂ)に示すように、車体側のシール部材（カバー１０ｂ、パックシール１０ｃ）を上記した車体側端部の固定面２ｎ-2に圧入して固定させることで、軸受内部空間を密封する。これにより、従動輪用及び駆動輪用の軸受ユニットを完成させることができる。   Then, after press-fitting the rotating wheel constituting body 16 and caulking the caulking region 12c, as shown in FIGS. 1 (a) and 1 (b), the vehicle body side seal members (cover 10b, pack seal 10c) are arranged as described above. The inner space of the bearing is sealed by being press-fitted and fixed to the fixed surface 2n-2 at the end portion of the vehicle body. Thereby, the bearing unit for driven wheels and a drive wheel can be completed.

ここで、車体側のシール部材（カバー１０ｂ、パックシール１０ｃ）を車体側端部の固定面２ｎ-2に圧入して固定させる際には、既に、車輪側のリップシール１０ａは、上記した車輪側端部の固定面２ｎ-1に正規の状態（即ち、予め設定された位置にセットされた状態）で固定されており、このような状態で、車体側のシール部材（カバー１０ｂ、パックシール１０ｃ）を圧入すると、その圧入ストローク寸法（圧入量、圧入距離）に相当する分だけ、軸受内部空間の圧力（内圧）が上昇する。   Here, when the vehicle body side seal member (cover 10b, pack seal 10c) is press-fitted and fixed to the fixing surface 2n-2 of the vehicle body side end, the wheel side lip seal 10a has already been mounted on the wheel. It is fixed to the fixed surface 2n-1 at the side end in a normal state (that is, a state set at a preset position). In such a state, the vehicle body side seal member (cover 10b, pack seal) is fixed. When 10c) is press-fitted, the pressure (internal pressure) in the bearing internal space increases by an amount corresponding to the press-fitting stroke dimension (press-fitting amount, press-fitting distance).

具体的に説明すると、車輪側及び車体側の各シール部材を静止輪（外輪）２に圧入させて固定させた軸受完成状態（図２(ａ),(ｂ)）における軸受内部空間の容積をＶＢ（静的空間容積ともいう）とし、また、車体側のシール部材（カバー１０ｂ、パックシール１０ｃ）を圧入させることで、その圧入ストローク寸法（圧入幅、圧入量、圧入距離）Ｌ（図１(ａ),(ｂ)）に相当する分だけ減少した軸受内部空間の容積をＶＣとすると、ＶＣ／ＶＢだけ軸受内部空間の圧力（内圧）が上昇する。   More specifically, the volume of the bearing internal space in the completed state of the bearing (FIGS. 2 (a) and 2 (b)) in which the wheel side and vehicle body side seal members are press-fitted into the stationary wheel (outer ring) 2 and fixed. VB (also referred to as a static space volume) and press-fitting a seal member (cover 10b, pack seal 10c) on the vehicle body side, the press-fitting stroke dimensions (press-fitting width, press-fitting amount, press-fitting distance) L (FIG. 1) When the volume of the bearing internal space reduced by the amount corresponding to (a) and (b)) is VC, the pressure (internal pressure) of the bearing internal space increases by VC / VB.

ここで、従動輪用の軸受ユニット（図１(ａ)）において、カバー１０ｂを圧入させる車体側端部の固定面２ｎ-2の直径（内径）をｄとすると、上記した容積ＶＣは、ＶＣ＝πＬｄ２／４となる。また、駆動輪用の軸受ユニット（図１(ｂ)）において、パックシール１０ｃ（シール片）を圧入させる車体側端部の固定面２ｎ-2の直径（内径）をｄ２とし、パックシール１０ｃ（スリンガ）を圧入させる車体側端部の固定面１６ｎの直径（外径）をｄ１とすると、上記した容積ＶＣは、ＶＣ＝πＬ（ｄ２２−ｄ１２）／４となる。 Here, in the bearing unit for the driven wheel (FIG. 1 (a)), when the diameter (inner diameter) of the fixed surface 2n-2 of the vehicle body side end portion into which the cover 10b is press-fitted is d, the above-described volume VC is VC. = the πLd 2/4. Further, in the bearing unit for the drive wheel (FIG. 1B), the diameter (inner diameter) of the fixed surface 2n-2 of the vehicle body side end portion into which the pack seal 10c (seal piece) is press-fitted is d2, and the pack seal 10c ( When the diameter (outer diameter) of the fixed surface 16n at the vehicle body side end portion into which the slinger is press-fitted is d1, the volume VC described above is VC = πL (d2 2 −d1 2 ) / 4.

このとき、軸受内部空間の圧力（内圧）については、ボイルシャルルの法則（ＰＶ＝ｎＲＴ）に従って、軸受ユニットの温度変化に応じて変化する。なお、圧力（内圧）は、ゲージ圧ではなく、絶対圧力とする。ここで、Ｐは気体の圧力［Ｐａ］、Ｖは気体が占める体積［ｍ３］、ｎは気体の物質量［モル数］、Ｒは１モルの気体定数、Ｔは気体の絶対温度［Ｋ］である。 At this time, the pressure (internal pressure) in the bearing internal space changes according to the temperature change of the bearing unit in accordance with Boyle's law (PV = nRT). The pressure (internal pressure) is not gauge pressure but absolute pressure. Here, P is the gas pressure [Pa], V is the volume occupied by the gas [m 3 ], n is the amount of the gas [mole number], R is the gas constant of 1 mol, and T is the absolute gas temperature [K]. ].

例えば、自動車の使用環境や使用条件などを考慮すると、軸受ユニットの温度（即ち、軸受温度）は、−４０℃（２３３Ｋ）程度から１６０℃（４３３Ｋ）程度まで変化する。これを圧力換算すれば、２０℃（２９３Ｋ）で圧力（内圧）が１００ｋＰａであったとすると、−４０℃では８０ｋＰａ（２３３／２９３）、１６０℃では１４８ｋＰａ（４３３／２９３）となり、軸受内部空間の圧力（内圧）は大きく変化する。   For example, considering the use environment and use conditions of an automobile, the temperature of the bearing unit (that is, the bearing temperature) varies from about −40 ° C. (233 K) to about 160 ° C. (433 K). When this is converted into pressure, if the pressure (internal pressure) is 20 kPa (293K) and 100 kPa, it becomes 80 kPa (233/293) at -40 ° C and 148 kPa (433/293) at 160 ° C. The pressure (internal pressure) varies greatly.

このような軸受ユニットでは、軸受温度の変化に伴って軸受内部空間の圧力（内圧）が変化した場合、その圧力（内圧）の変化に応じて、上記したシール部材（車輪側のリップシール１０ａ、車体側のカバー１０ｂ又はパックシール１０ｃ）が移動するような事態は生じないが、その弊害は、当該シール部材における摺動状態に現れる。なお、シール部材における摺動状態としては、例えば、車輪側のリップシール１０ａでは、回転輪（内輪）４の摺動面４ｎ-1に対する摺動状態を指し、また、車体側のパックシール１０ｃでは、当該パックシール１０ｃを構成するシール片とスリンガとの摺動状態を指す。   In such a bearing unit, when the pressure (internal pressure) of the bearing internal space changes with changes in the bearing temperature, the above-described seal member (the lip seal 10a on the wheel side, Although a situation in which the vehicle body side cover 10b or the pack seal 10c) does not move occurs, the adverse effect appears in the sliding state of the seal member. As the sliding state of the seal member, for example, the lip seal 10a on the wheel side indicates the sliding state with respect to the sliding surface 4n-1 of the rotating wheel (inner ring) 4, and the pack seal 10c on the vehicle body side. The sliding state of the seal piece and the slinger constituting the pack seal 10c is indicated.

ここで、軸受内部空間の圧力（内圧）が高くなり過ぎると（例えば、シール部材のリーク限界を超えると）、当該シール部材からの「エア漏れ」や「潤滑剤漏れ」が発生すると共に、その軸受温度が低下したときには、軸受内部空間の圧力（内圧）の低下（負圧）が引き起こされる。そして、このときの圧力（内圧）の低下（負圧）の程度によっては、上記した摺動状態における摺動抵抗が上昇し、これにより、回転トルクや磨耗が増大するだけでなく、当該シール部材を介して軸受内部空間に異物（例えば、水、泥、塵埃）が浸入し易くなる。また、潤滑剤（油剤）の蒸発を招くため、潤滑状態が悪くなり、軸受寿命にも悪影響を及ぼす。   Here, when the pressure (internal pressure) in the bearing internal space becomes too high (for example, when the leak limit of the seal member is exceeded), “air leak” and “lubricant leak” from the seal member occur, When the bearing temperature decreases, a decrease (negative pressure) in the pressure (internal pressure) in the bearing internal space is caused. In addition, depending on the degree of reduction (negative pressure) of the pressure (internal pressure) at this time, the sliding resistance in the above-described sliding state increases, thereby not only increasing rotational torque and wear, but also the sealing member. This makes it easier for foreign matter (for example, water, mud, dust) to enter the bearing internal space. Further, since the lubricant (oil agent) is evaporated, the lubrication state is deteriorated and the bearing life is also adversely affected.

そこで、シール部材のリーク限界を超えないように、軸受温度の変化に伴う軸受内部空間の圧力（内圧）の変化を緩和させるための技術思想が提案されているが（例えば、特許文献２,３参照）、いずれも、既存の軸受構成をそのまま用いることができず、新たな構成を付加したり、別途改良を加えるといった面倒な手立てが必要である。このため、その手立てに要する分だけ軸受ユニットの製造コストが上昇してしまう。   Therefore, a technical idea for alleviating a change in pressure (internal pressure) in the bearing internal space accompanying a change in bearing temperature has been proposed so as not to exceed the leak limit of the seal member (for example, Patent Documents 2 and 3). In either case, the existing bearing configuration cannot be used as it is, and a troublesome means such as adding a new configuration or adding another improvement is required. For this reason, the manufacturing cost of the bearing unit is increased by the amount required for the preparation.

なお、ルシャトリエの原理による圧平衡（例えば、２ＮＯ２⇔Ｎ２Ｏ２、Ｎ２＋３Ｈ２⇔２ＮＨ３）や、固−液−気平衡（例えば、代替フロン）による圧力調整も、圧力以上に温度に対する反応が強く、逆反応になってしまう上、軸受内部空間のエアを毒性の強い気体、或いは、軌道輪（静止輪２、回転輪４）に水素脆性を発生する虞のある気体に置換する必要があるため、実施不可能であった。 It should be noted that pressure adjustment based on Le Chatelier's principle (for example, 2NO 2 ⇔N 2 O 2 , N 2 + 3H 2 ⇔2NH 3 ) and solid-liquid-gas equilibrium (for example, alternative chlorofluorocarbon) can be performed at a temperature higher than the pressure. In addition, the air in the bearing inner space is replaced with a highly toxic gas or a gas that may cause hydrogen embrittlement in the race ring (stationary ring 2 and rotating ring 4). Because it was necessary, it was impossible to implement.

本発明は、上記したような問題を解決するためになされており、その目的は、既存の軸受構成をそのまま用いて、容易に、軸受温度の変化に伴う軸受内部空間の圧力（内圧）の変化を緩和させることを可能にする低コストの軸受ユニットを提供することにある。   The present invention has been made in order to solve the above-described problems, and an object of the present invention is to easily change the pressure (internal pressure) in the bearing internal space as the bearing temperature changes, using the existing bearing configuration as it is. It is an object of the present invention to provide a low-cost bearing unit that can alleviate the above.

かかる目的を達成するために、本発明は、相対回転可能に対向配置された軌道輪と、軌道輪に圧入されて固定され、かつ、当該軌道輪間に区画された軸受内部空間を、その軸方向両側から密封するためのシール部材とを備えた軸受ユニットであって、双方のシール部材を軌道輪に圧入させて固定させた状態における軸受内部空間の容積をＶＢとし、一方のシール部材を軌道輪に圧入させて固定させた状態において、他方のシール部材を軌道輪に圧入させることで、その圧入ストローク寸法に相当する分だけ減少した軸受内部空間の容積をＶＣとすると、想定軸受温度の下限で軸受内部空間の圧力が負圧にならず、かつ、想定軸受温度の上限で軸受内部空間の圧力がシール部材のリーク限界を超えないようなＶＢとＶＣの比率を得るために、他方のシール部材を軌道輪に圧入させる圧入ストローク寸法が調整されている。
本発明において、軸受想定温度の下限で軸受内部空間の圧力が負圧にならないようにするため、ＶＣは、ＶＢの０.３倍以上となるように設定されている。
本発明において、想定軸受温度の上限で軸受内部空間の圧力がシール部材のリーク限界を超えないようにするため、ＶＣは、ＶＢの０.７倍以下となるように設定されている。 In order to achieve such an object, the present invention provides a bearing ring that is disposed so as to be relatively rotatable and a bearing inner space that is press-fitted into the bearing ring and that is partitioned between the bearing rings. Bearing unit having a sealing member for sealing from both sides in the direction, and the volume of the bearing internal space in a state where both the sealing members are press-fitted into the race ring and fixed, is VB, and one seal member is the raceway When the volume of the bearing internal space reduced by an amount corresponding to the press-fitting stroke dimension is VC by pressing the other seal member into the race ring while being pressed into the ring and fixed, the lower limit of the assumed bearing temperature In order to obtain the ratio of VB and VC so that the pressure in the bearing internal space does not become negative and the pressure in the bearing internal space does not exceed the leak limit of the seal member at the upper limit of the assumed bearing temperature. Press fitting stroke dimension is adjusted for press-fitting the sealing member to the bearing ring.
In the present invention, VC is set to be not less than 0.3 times VB so that the pressure in the bearing internal space does not become negative at the lower limit of the assumed bearing temperature.
In the present invention, VC is set to be not more than 0.7 times VB so that the pressure in the bearing internal space does not exceed the leak limit of the seal member at the upper limit of the assumed bearing temperature.

本発明によれば、既存の軸受構成をそのまま用いて、容易に、軸受温度の変化に伴う軸受内部空間の圧力（内圧）の変化を緩和させることを可能にする低コストの軸受ユニットを実現することができる。   According to the present invention, a low-cost bearing unit that can easily reduce a change in pressure (internal pressure) in a bearing internal space accompanying a change in bearing temperature by using an existing bearing configuration as it is is realized. be able to.

(ａ)は、従動輪用の軸受ユニットにおいて、カバーを圧入するプロセスを模式的に示す断面図、(ｂ)は、駆動輪用の軸受ユニットにおいて、パックシールを圧入するプロセスを模式的に示す断面図。(a) is a cross-sectional view schematically showing a process for press-fitting a cover in a bearing unit for a driven wheel, and (b) schematically shows a process for press-fitting a pack seal in a bearing unit for a drive wheel. Sectional drawing. (ａ)は、軸受完成状態における従動輪用の軸受ユニットの構成を示す断面図、(ｂ)は、軸受完成状態における駆動輪用の軸受ユニットの構成を示す断面図。(a) is sectional drawing which shows the structure of the bearing unit for driven wheels in the bearing completion state, (b) is sectional drawing which shows the structure of the bearing unit for driving wheels in the bearing completion state.

以下、本発明の一実施形態に係る軸受ユニットについて説明する。
なお、本実施形態は、図１及び図２に示された軸受ユニットの改良であるため、以下、同一の図面（図１,２）を用いて、その改良部分に係る軸受ユニットについての説明にとどめる。 Hereinafter, a bearing unit according to an embodiment of the present invention will be described.
Since the present embodiment is an improvement of the bearing unit shown in FIGS. 1 and 2, hereinafter, the same drawing (FIGS. 1 and 2) will be used to describe the bearing unit according to the improved portion. Stay.

本実施形態では、車体側のシール部材（カバー１０ｂ、パックシール１０ｃ）を圧入させる圧入ストローク寸法（圧入幅、圧入量、圧入距離）Ｌ（図１(ａ),(ｂ)）を調整することで、軸受完成状態（図２(ａ),(ｂ)）における軸受内部空間の容積ＶＢ（静的空間容積）と、圧入ストローク寸法Ｌに相当する分だけ減少した軸受内部空間の容積ＶＣとの比率（ＶＣ／ＶＢ）を適切な範囲に設定し、これにより、シール部材のリーク限界を超えないように、軸受温度の変化に伴う軸受内部空間の圧力（内圧）の変化を緩和させることを可能にする軸受ユニットを設計する。   In the present embodiment, the press-fitting stroke dimensions (press-fitting width, press-fitting amount, press-fitting distance) L (FIGS. 1A and 1B) for press-fitting the body side seal members (cover 10b, pack seal 10c) are adjusted. Thus, the volume VB (static space volume) of the bearing internal space in the completed bearing state (FIGS. 2A and 2B) and the volume VC of the bearing internal space decreased by an amount corresponding to the press-fitting stroke dimension L. By setting the ratio (VC / VB) to an appropriate range, it is possible to mitigate changes in the pressure (internal pressure) in the bearing internal space accompanying changes in the bearing temperature so that the leak limit of the seal member is not exceeded. Design the bearing unit to be

かかる軸受ユニットの設計では、想定軸受温度の下限で軸受内部空間の圧力（内圧）が負圧にならず、かつ、想定軸受温度の上限で軸受内部空間の圧力（内圧）がシール部材のリーク限界を超えないようなＶＢとＶＣの比率（ＶＣ／ＶＢ）を得るために、車体側のシール部材（カバー１０ｂ、パックシール１０ｃ）を圧入させる圧入ストローク寸法（圧入幅、圧入量、圧入距離）Ｌが調整されている。なお、シール部材のリーク限界とは、密封状態が崩れる限界、即ち、軸受内部からの空気や潤滑剤の漏洩が始まる圧力を指す。   In such a bearing unit design, the pressure (internal pressure) in the bearing internal space does not become negative at the lower limit of the assumed bearing temperature, and the pressure (internal pressure) in the bearing inner space at the upper limit of the assumed bearing temperature is the leakage limit of the seal member. Press-fit stroke dimensions (press-fit width, press-fit amount, press-fit distance) L for press-fitting the vehicle body side seal member (cover 10b, pack seal 10c) to obtain a ratio of VB to VC (VC / VB) that does not exceed A Has been adjusted. The leak limit of the seal member refers to the limit at which the sealed state collapses, that is, the pressure at which leakage of air and lubricant from the inside of the bearing starts.

本実施形態において、軸受完成状態（図２(ａ),(ｂ)）における軸受内部空間の容積ＶＢは、静的空間容積によって定義される。具体的には、静的空間容積ＶＢは、その径方向が静止輪（外輪）２の内周面２ｎの輪殻（輪郭）と、回転輪（内輪）４の外周面４ｍ（具体的には、ハブ１２と回転輪構成体１６とから成る回転輪（内輪）４の外周面４ｍ）の輪殻（輪郭）とで定義され、かつ、軸方向がシール部材（車輪側のリップシール１０ａ、車体側のカバー１０ｂ又はパックシール１０ｃ）の軸受内部空間側の輪殻（輪郭）で定義される空間容積から、複数の転動体６,８、保持器１８、潤滑剤（例えば、グリース、油）の合計の体積を引いた差で定義される。なお、従動輪用の軸受ユニット（図１(ａ)）においては、回転輪（内輪）２の軸方向内側（回転輪構成体１６の周端部１６ｓと、加締め領域１２ｃと、加締め領域１２ｃの内径の凹部により構成される面）の輪殻（輪郭）に基づいて、上記した静的空間容積がさらに定義される。この場合、かかる従動輪用の輪殻（輪郭）とカバー１０ｂの軸受内部空間面との間の空間容積分、従動輪の空間容積は、駆動輪の空間容積よりも大きくなる。   In the present embodiment, the volume VB of the bearing internal space in the completed bearing state (FIGS. 2A and 2B) is defined by the static space volume. Specifically, the static space volume VB has a radial direction whose ring direction is an annular shell (outline) of the inner peripheral surface 2n of the stationary ring (outer ring) 2 and an outer peripheral surface 4m (specifically, the rotating ring (inner ring) 4). And a ring shell (contour) of the outer peripheral surface 4m) of the rotating wheel (inner ring) 4 comprising the hub 12 and the rotating wheel constituting body 16, and the axial direction is a seal member (lip seal 10a on the wheel side, vehicle body From the space volume defined by the ring shell (contour) on the bearing inner space side of the side cover 10b or the pack seal 10c), a plurality of rolling elements 6, 8, cage 18, lubricant (for example, grease, oil) Defined as the difference minus the total volume. In the bearing unit for the driven wheel (FIG. 1A), the inner side in the axial direction of the rotating wheel (inner ring) 2 (the peripheral end portion 16s of the rotating wheel component 16, the crimping region 12c, and the crimping region) The static space volume described above is further defined on the basis of the annular shell (contour) of the surface formed by the recess having the inner diameter of 12c. In this case, the space volume of the driven wheel is larger than the space volume of the driving wheel by the space volume between the ring shell (contour) for the driven wheel and the bearing internal space surface of the cover 10b.

また、従動輪用の軸受ユニット（図１(ａ)）において、カバー１０ｂを圧入させる静止輪（外輪）２の車体側端部の固定面２ｎ-2の直径（内径）をｄとすると、圧入ストローク寸法Ｌに相当する分だけ減少した軸受内部空間の容積ＶＣは、ＶＣ＝πＬｄ２／４と定義される。また、駆動輪用の軸受ユニット（図１(ｂ)）において、パックシール１０ｃ（シール片）を圧入させる静止輪（外輪）２の車体側端部の固定面２ｎ-2の直径（内径）をｄ２とし、パックシール１０ｃ（スリンガ）を圧入させる車体側端部の固定面１６ｎの直径（外径）をｄ１とすると、圧入ストローク寸法Ｌに相当する分だけ減少した軸受内部空間の容積ＶＣは、ＶＣ＝πＬ（ｄ２２−ｄ１２）／４と定義される。 Further, in the bearing unit for the driven wheel (FIG. 1 (a)), if the diameter (inner diameter) of the fixed surface 2n-2 at the end of the vehicle body side of the stationary wheel (outer ring) 2 into which the cover 10b is press-fitted is d, press-fitting volume VC of the bearing inner space was reduced by an amount corresponding to the stroke dimension L is defined as VC = πLd 2/4. Further, in the bearing unit for the drive wheel (FIG. 1 (b)), the diameter (inner diameter) of the fixed surface 2n-2 at the vehicle body side end portion of the stationary wheel (outer ring) 2 into which the pack seal 10c (seal piece) is press-fitted. When d2 is d1, and the diameter (outer diameter) of the fixed surface 16n at the vehicle body side end portion into which the pack seal 10c (slinger) is press-fitted is d1, the volume VC of the bearing internal space reduced by an amount corresponding to the press-fitting stroke dimension L is It is defined as VC = πL (d2 2 −d1 2 ) / 4.

なお、圧入ストローク寸法Ｌは、静止輪（外輪）２の車体側端部に形成された面取り部（図示しない）の状態（例えば、大きさ、形状、傾きなど）に応じて、車体側のシール部材（カバー１０ｂ、パックシール１０ｃ）を車体側端部の固定面２ｎ-2に圧入させる実際の圧入幅（圧入量、圧入距離）から、圧入前に当該静止輪（外輪）２の車体側端部と車体側のシール部材（カバー１０ｂ、パックシール１０ｃ）とが重なり合う寸法（幅、量、距離）を引いた差で定義される。   The press-fitting stroke dimension L depends on the state (for example, size, shape, inclination, etc.) of the chamfered portion (not shown) formed at the vehicle body side end of the stationary wheel (outer ring) 2. From the actual press-fitting width (press-fitting amount, press-fitting distance) in which the members (cover 10b, pack seal 10c) are press-fitted into the fixed surface 2n-2 at the end of the vehicle body, the end of the stationary wheel (outer ring) 2 on the vehicle side before press-fitting This is defined as a difference obtained by subtracting dimensions (width, amount, distance) at which the portion and the vehicle body side seal member (cover 10b, pack seal 10c) overlap.

この場合、軸受温度の変化範囲と、シール部材のリーク限界とを想定し、軸受想定温度の下限で軸受内部空間の圧力（内圧）が負圧にならず、かつ、想定軸受温度の上限で軸受内部空間の圧力（内圧）即ち“正圧”がシール部材のリーク限界を超えないように、常温での軸受内部空間の圧力（内圧）を設定するため、圧入ストローク寸法Ｌが調整されている。   In this case, assuming the change range of the bearing temperature and the leak limit of the seal member, the bearing internal space pressure (internal pressure) does not become negative at the lower limit of the assumed bearing temperature, and the bearing at the upper limit of the assumed bearing temperature. In order to set the pressure (internal pressure) of the bearing internal space at normal temperature so that the pressure (internal pressure) of the internal space, that is, “positive pressure” does not exceed the leak limit of the seal member, the press-fitting stroke dimension L is adjusted.

例えば、軸受想定温度を−４０℃（２３３Ｋ）〜１６０℃（４３３Ｋ）とし、シール部材のリーク限界を２５０ｋＰａとする場合を想定する。ここで、軸受ユニットの組立場の温度を２０℃（２９３Ｋ）、気圧を１００ｋＰａとすると、軸受想定温度の下限で軸受内部空間の圧力（内圧）が負圧にならないようにするためには、２０℃（２９３Ｋ）における軸受内部空間の圧力（内圧）は、１２６ｋＰａ（１００×２９３／２３３）以上であるため、これにより、ＶＢとＶＣの関係を、ＶＣ≧０.２６（≒０.３）ＶＢとなるように設定すればよい。   For example, it is assumed that the assumed bearing temperature is −40 ° C. (233 K) to 160 ° C. (433 K) and the leak limit of the seal member is 250 kPa. Here, assuming that the assembly unit temperature of the bearing unit is 20 ° C. (293 K) and the atmospheric pressure is 100 kPa, in order to prevent the pressure (internal pressure) in the bearing internal space from becoming a negative pressure at the lower limit of the assumed bearing temperature, 20 Since the pressure (internal pressure) of the bearing internal space at 126 ° C. (293 K) is not less than 126 kPa (100 × 293/233), the relationship between VB and VC can be expressed as VC ≧ 0.26 (≈0.3) VB. Should be set to be.

このとき、想定軸受温度の上限で軸受内部空間の圧力（内圧）即ち“正圧”がシール部材のリーク限界（２５０ｋＰａ）を超えないようにするためには、２０℃（２９３Ｋ）における軸受内部空間の圧力（内圧）は、１６９ｋＰａ（２５０×２９３／４３３）以下であるため、これにより、ＶＢとＶＣの関係を、ＶＣ≦０.６９（≒０.７）ＶＢとなるように設定すればよい。   At this time, in order to prevent the pressure (internal pressure), that is, “positive pressure” in the bearing inner space from exceeding the leak limit (250 kPa) of the seal member at the upper limit of the assumed bearing temperature, the bearing inner space at 20 ° C. (293 K). Therefore, the relationship between VB and VC can be set to satisfy VC ≦ 0.69 (≈0.7) VB. .

具体的な実施例として、例えば乗用車クラスの軸受ユニットにおいて、その軸受内部空間の容積は５０ｃｃ位であり、シール部材（例えば、図１(ａ)に示されたカバー１０ｂ）を圧入させる静止輪（外輪）２の車体側端部の固定面２ｎ-2の直径（内径）ｄは７０ｍｍ位である。この場合、シール部材（カバー１０ｂ）を車体側端部の固定面２ｎ-2に圧入させる際に、その圧入ストローク寸法Ｌに相当する分だけ減少した軸受内部空間の容積ＶＣを、上記した範囲（ＶＣ≧０.３×５０、かつ、ＶＣ≦０.７×５０）となるようにするためには、当該圧入ストローク寸法Ｌは、４ｍｍ≦Ｌ≦９ｍｍに調整すればよい。   As a specific embodiment, for example, in a passenger car class bearing unit, the volume of the bearing internal space is about 50 cc, and a stationary wheel (for example, a cover 10b shown in FIG. 1A) is press-fitted. The diameter (inner diameter) d of the fixed surface 2n-2 at the vehicle body side end portion of the outer ring) 2 is about 70 mm. In this case, when the seal member (cover 10b) is press-fitted into the fixed surface 2n-2 of the vehicle body side end portion, the volume VC of the bearing internal space reduced by an amount corresponding to the press-fitting stroke dimension L is within the above range ( VC ≧ 0.3 × 50 and VC ≦ 0.7 × 50), the press-fitting stroke dimension L may be adjusted to 4 mm ≦ L ≦ 9 mm.

以上、本実施形態によれば、シール部材（カバー１０ｂ、パックシール１０ｃ）を圧入させる圧入ストローク寸法（圧入幅、圧入量、圧入距離）Ｌ（図１(ａ),(ｂ)）を調整することで、軸受温度が変化しても、想定軸受温度の下限で軸受内部空間の圧力（内圧）が負圧にならず、かつ、想定軸受温度の上限で軸受内部空間の圧力（内圧）がシール部材のリーク限界を超えないようなＶＢとＶＣの比率（ＶＣ／ＶＢ）を得ることができる。これにより、軸受温度が変化しても、シール部材のリーク限界を超えないように、軸受内部空間の圧力（内圧）の変化を緩和させることを可能にする軸受ユニットを実現することができる。   As described above, according to the present embodiment, the press-fitting stroke dimensions (press-fitting width, press-fitting amount, press-fitting distance) L (FIGS. 1A and 1B) for press-fitting the seal member (cover 10b, pack seal 10c) are adjusted. Therefore, even if the bearing temperature changes, the pressure (internal pressure) in the bearing internal space does not become negative at the lower limit of the assumed bearing temperature, and the pressure (internal pressure) in the bearing inner space does not seal at the upper limit of the assumed bearing temperature. A ratio of VB and VC (VC / VB) that does not exceed the leakage limit of the member can be obtained. As a result, it is possible to realize a bearing unit that makes it possible to mitigate changes in the pressure (internal pressure) in the bearing internal space so as not to exceed the leak limit of the seal member even if the bearing temperature changes.

なお、上記した実施形態では、車体側のシール部材として、静止輪（外輪）２の車体側端部の内径側に圧入させるカバー１０ｂやパックシール１０ｃを想定して説明したが、これに限定されることはなく、例えば、静止輪（外輪）２の車体側端部の外径側に圧入させるカバー、或いは、その一部が樹脂で成形されたり、回転検出用センサが一体化されたような種々のシール部材についても、上記した圧入ストローク寸法Ｌに調整することで、本実施形態と同様の作用効果を実現することができる。   In the above-described embodiment, the cover 10b and the pack seal 10c that are press-fitted into the inner diameter side of the end portion of the vehicle body side of the stationary wheel (outer ring) 2 are described as the vehicle body side seal member. However, the present invention is not limited to this. For example, a cover that is press-fitted into the outer diameter side of the end of the vehicle body side of the stationary wheel (outer ring) 2 or a part thereof is molded of resin, or a rotation detection sensor is integrated. For various seal members, by adjusting the press-fitting stroke dimension L as described above, it is possible to achieve the same effects as the present embodiment.

２ 軌道輪（静止輪（外輪））
４ 軌道輪（回転輪（内輪））
１０ａ シール部材（リップシール）
１０ｂ シール部材（カバー）
１０ｃ シール部材（パックシール）
Ｌ シール部材を軌道輪に圧入させる圧入ストローク寸法 2 Track ring (stationary wheel (outer ring))
4 race ring (rotating ring (inner ring))
10a Seal member (lip seal)
10b Seal member (cover)
10c Seal member (pack seal)
L Press-fit stroke dimensions to press-fit the seal member into the race

Claims (3)

相対回転可能に対向配置された軌道輪と、
軌道輪に圧入されて固定され、かつ、当該軌道輪間に区画された軸受内部空間を、その軸方向両側から密封するためのシール部材とを備えた軸受ユニットであって、
双方のシール部材を軌道輪に圧入させて固定させた状態における軸受内部空間の容積をＶＢとし、
一方のシール部材を軌道輪に圧入させて固定させた状態において、他方のシール部材を軌道輪に圧入させることで、その圧入ストローク寸法に相当する分だけ減少した軸受内部空間の容積をＶＣとすると、
想定軸受温度の下限で軸受内部空間の圧力が負圧にならず、かつ、想定軸受温度の上限で軸受内部空間の圧力がシール部材のリーク限界を超えないようなＶＢとＶＣの比率を得るために、他方のシール部材を軌道輪に圧入させる圧入ストローク寸法が調整されていることを特徴とする軸受ユニット。 A bearing ring arranged opposite to be relatively rotatable,
A bearing unit that includes a seal member that is press-fitted into and fixed to the bearing ring and that seals the bearing internal space defined between the bearing rings from both axial sides thereof,
The volume of the bearing internal space in a state where both the seal members are press-fitted into the bearing ring and fixed is VB,
In a state in which one seal member is press-fitted into the bearing ring and fixed, the volume of the bearing internal space reduced by an amount corresponding to the press-fitting stroke size by pressing the other seal member into the race ring is VC. ,
To obtain a ratio of VB and VC so that the pressure in the bearing internal space does not become negative at the lower limit of the assumed bearing temperature and the pressure in the bearing inner space does not exceed the leakage limit of the seal member at the upper limit of the assumed bearing temperature. Further, a press-fitting stroke dimension for press-fitting the other seal member into the race is adjusted. 軸受想定温度の下限で軸受内部空間の圧力が負圧にならないようにするため、ＶＣは、ＶＢの０.３倍以上となるように設定されていることを特徴とする請求項１に記載の軸受ユニット。   2. The VC according to claim 1, wherein VC is set to be not less than 0.3 times VB in order to prevent the pressure in the bearing internal space from becoming a negative pressure at the lower limit of the assumed bearing temperature. Bearing unit. 想定軸受温度の上限で軸受内部空間の圧力がシール部材のリーク限界を超えないようにするため、ＶＣは、ＶＢの０.７倍以下となるように設定されていることを特徴とする請求項１又は２に記載の軸受ユニット。   The VC is set to be not more than 0.7 times VB so that the pressure in the bearing internal space does not exceed the leak limit of the seal member at the upper limit of the assumed bearing temperature. The bearing unit according to 1 or 2.
JP2011150557A 2011-07-07 2011-07-07 Bearing unit Withdrawn JP2013019427A (en)

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