JP4281545B2

JP4281545B2 - Toroidal type continuously variable transmission and manufacturing method thereof

Info

Publication number: JP4281545B2
Application number: JP2003419023A
Authority: JP
Inventors: 宏泰吉岡
Original assignee: NSK Ltd
Current assignee: NSK Ltd
Priority date: 2003-12-17
Filing date: 2003-12-17
Publication date: 2009-06-17
Anticipated expiration: 2023-12-17
Also published as: JP2005180497A

Description

この発明は、例えば自動車の自動変速機用の変速ユニットとして、或は各種産業機械用の変速機として、それぞれ利用できるトロイダル型無段変速機とその製造方法の改良に関する。 The present invention relates to a toroidal continuously variable transmission that can be used, for example, as a transmission unit for an automatic transmission of an automobile or as a transmission for various industrial machines, and to an improvement of a manufacturing method thereof.

自動車用自動変速機としてトロイダル型無段変速機を使用する事が研究され、一部で実施されている。このトロイダル型無段変速機は、例えば特許文献１に記載されている様な構成を有する。図１〜２は、このトロイダル型無段変速機の基本構成を略示している。この図１〜２に示した構造では、入力軸１と同心に入力側ディスク２を支持し、この入力軸１と同心に配置された出力軸３の端部に出力側ディスク４を固定している。又、トロイダル型無段変速機を納めたケーシング（図示省略）の内側に、上記入力軸１並びに出力軸３に対し捻れの位置にある枢軸５、５を中心として揺動するトラニオン６、６を設けている。 The use of toroidal continuously variable transmissions as automatic transmissions for automobiles has been studied and implemented in part. This toroidal continuously variable transmission has a configuration as described in Patent Document 1, for example. 1 and 2 schematically show the basic configuration of this toroidal-type continuously variable transmission. In the structure shown in FIGS. 1 and 2, the input side disk 2 is supported concentrically with the input shaft 1, and the output side disk 4 is fixed to the end of the output shaft 3 disposed concentrically with the input shaft 1. Yes. Further, trunnions 6 and 6 that swing around pivots 5 and 5 that are twisted with respect to the input shaft 1 and the output shaft 3 are disposed inside a casing (not shown) in which a toroidal-type continuously variable transmission is housed. Provided.

上記各トラニオン６、６は、長さ方向（図１〜２の表裏方向）両端面に上記枢軸５、５を、各トラニオン６、６毎に互いに同心に、各トラニオン６、６毎に１対ずつ設けている。これら各枢軸５、５の中心軸は、上記各ディスク２、４の中心軸と交差する事はないが、これら各ディスク２、４の中心軸の方向に対し直角若しくはほぼ直角方向である、捩れの位置に存在する。又、上記各トラニオン６、６の中心部には支持軸７、７の基半部を支持し、上記枢軸５、５を中心として各トラニオン６、６を揺動させる事により、上記各支持軸７、７の傾斜角度の調節を自在としている。各トラニオン６、６に支持された支持軸７、７の先半部周囲には、それぞれパワーローラ８、８を回転自在に支持している。そして、これら各パワーローラ８、８を、上記入力側、出力側両ディスク２、４の内側面２ａ、４ａ同士の間に挟持している。 Each trunnion 6, 6 has the pair of pivots 5, 5 concentric with each other for each trunnion 6, 6 on both ends in the length direction (front and back direction in FIGS. 1 and 2). It is provided one by one. The central axes of the pivots 5 and 5 do not intersect with the central axes of the disks 2 and 4 but are twisted at right angles or substantially perpendicular to the direction of the central axes of the disks 2 and 4. Exists in the position. Further, the base half of the support shafts 7 and 7 is supported at the center of the trunnions 6 and 6, and the trunnions 6 and 6 are swung around the pivots 5 and 5 so that the support shafts are supported. 7 and 7 can be adjusted freely. Power rollers 8 and 8 are rotatably supported around the front half portions of the support shafts 7 and 7 supported by the trunnions 6 and 6, respectively. These power rollers 8 and 8 are sandwiched between the inner side surfaces 2a and 4a of the input side and output side disks 2 and 4, respectively.

上記入力側、出力側両ディスク２、４の互いに対向する内側面２ａ、４ａは、それぞれ断面が、上記枢軸５を中心とする円弧若しくはこの様な円弧に近い曲線を回転させて得られる、断面円弧状の凹面をなしている。そして、球状凸面に形成された各パワーローラ８、８の周面８ａ、８ａを、上記内側面２ａ、４ａに当接させている。又、上記入力軸１と入力側ディスク２との間には、ローディングカム装置９を設け、このローディングカム装置９によって上記入力側ディスク２を、出力側ディスク４に向け弾性的に押圧しつつ、回転駆動自在としている。 The inner side surfaces 2a and 4a of the input side and output side discs 2 and 4 facing each other are obtained by rotating a cross section of an arc centered on the pivot 5 or a curve close to such an arc. It has an arcuate concave surface. And the peripheral surfaces 8a and 8a of each power roller 8 and 8 formed in the spherical convex surface are made to contact | abut to the said inner surface 2a and 4a. Further, a loading cam device 9 is provided between the input shaft 1 and the input side disc 2, and the input cam 2 is elastically pressed toward the output side disc 4 by the loading cam device 9. It can be freely rotated.

上述の様に構成されるトロイダル型無段変速機の使用時、入力軸１の回転に伴って上記ローディングカム装置９が上記入力側ディスク２を、上記複数のパワーローラ８、８に押圧しつつ回転させる。そして、この入力側ディスク２の回転が、上記複数のパワーローラ８、８を介して出力側ディスク４に伝達され、この出力側ディスク４に固定の出力軸３が回転する。 When the toroidal continuously variable transmission configured as described above is used, the loading cam device 9 presses the input side disk 2 against the plurality of power rollers 8 and 8 as the input shaft 1 rotates. Rotate. The rotation of the input side disk 2 is transmitted to the output side disk 4 via the plurality of power rollers 8, 8, and the output shaft 3 fixed to the output side disk 4 rotates.

入力軸１と出力軸３との回転速度を変える場合で、先ず入力軸１と出力軸３との間で減速を行なう場合には、枢軸５、５を中心として前記各トラニオン６、６を揺動させ、上記各パワーローラ８、８の周面８ａ、８ａが図１に示す様に、入力側ディスク２の内側面２ａの中心寄り部分と出力側ディスク４の内側面４ａの外周寄り部分とにそれぞれ当接する様に、前記各支持軸７、７を傾斜させる。反対に、増速を行なう場合には、上記各トラニオン６、６を揺動させ、上記各パワーローラ８、８の周面８ａ、８ａが図２に示す様に、入力側ディスク２の内側面２ａの外周寄り部分と出力側ディスク４の内側面４ａの中心寄り部分とに、それぞれ当接する様に、上記各支持軸７、７を傾斜させる。これら各支持軸７、７の傾斜角度を図１と図２との中間にすれば、入力軸１と出力軸３との間で、中間の変速比を得られる。 When the rotational speeds of the input shaft 1 and the output shaft 3 are changed and when the deceleration is first performed between the input shaft 1 and the output shaft 3, the trunnions 6 and 6 are swung around the pivot shafts 5 and 5. As shown in FIG. 1, the peripheral surfaces 8a and 8a of the power rollers 8 and 8 are arranged near the center of the inner surface 2a of the input side disk 2 and the outer peripheral portion of the inner surface 4a of the output side disk 4, respectively. The support shafts 7 and 7 are inclined so as to contact each other. On the contrary, when the speed is increased, the trunnions 6, 6 are swung so that the peripheral surfaces 8a, 8a of the power rollers 8, 8 are as shown in FIG. The support shafts 7 and 7 are inclined so as to abut the outer peripheral portion 2a and the central portion of the inner side surface 4a of the output disk 4 respectively. If the inclination angles of the support shafts 7 and 7 are set in the middle between those shown in FIGS. 1 and 2, an intermediate gear ratio can be obtained between the input shaft 1 and the output shaft 3.

上述の様に構成し作用するトロイダル型無段変速機の運転時に、上記両ディスク２、４の内側面２ａ、４ａと上記各パワーローラ８、８の周面８ａ、８ａとの転がり接触部（トラクション部）には、トラクションオイルの油膜を介在させる。このトラクションオイルは、このトラクション部で動力の伝達を行なわせる役目の他、各転がり軸受等の可動部を潤滑する役目を有する為、構成各部材から離脱したバリや摩耗粉等の硬質金属製の異物が混入する事が避けられない。この様な異物の存在は、上記トラクション部を構成する上記各面２ａ、４ａ、８ａの転がり疲れ寿命を低下させる原因となる。この為、異物が混入したトラクションオイルを使用した場合にも上記各面２ａ、４ａ、８ａの転がり疲れ寿命を確保する為に従来から、上記両ディスク２、４及び上記各パワーローラ８、８の表面の残留オーステナイト量を高くする事が行なわれている。そして、この残留オーステナイト量を高くする為に、従来からトロイダル型無段変速機以外の分野で広く行なわれていた熱処理である、浸炭処理や浸炭窒化処理を、上記各部材２、４、８の表面処理にもそのまま利用していた。これら各部材にこの様な熱処理を施す事に就いては、例えば、特許文献２、３等に記載されている。 During operation of the toroidal type continuously variable transmission constructed and operated as described above, rolling contact portions between the inner surfaces 2a, 4a of the disks 2, 4 and the peripheral surfaces 8a, 8a of the power rollers 8, 8 ( A traction oil film is interposed in the traction section. This traction oil has the role of transmitting power in this traction part, and also has the role of lubricating moving parts such as rolling bearings, so it is made of hard metal such as burrs and wear powder that has separated from the constituent members. It is inevitable that foreign matter gets mixed in. The presence of such foreign matters causes the rolling fatigue life of the surfaces 2a, 4a and 8a constituting the traction portion to be reduced. For this reason, in order to ensure the rolling fatigue life of each of the surfaces 2a, 4a, 8a even when traction oil mixed with foreign matter is used, the two disks 2, 4 and the power rollers 8, 8 have been conventionally used. The amount of retained austenite on the surface is increased. In order to increase the amount of retained austenite, carburizing treatment and carbonitriding treatment, which are heat treatments conventionally performed in fields other than toroidal-type continuously variable transmissions, are performed on each of the members 2, 4, 8. It was also used for surface treatment. For example, Patent Documents 2 and 3 describe how to perform such heat treatment on these members.

ところで、トロイダル型無段変速機を構成する入力側、出力側各ディスク２、４や各パワーローラ８、８は、相手部材との転がり接触部分で、上記油膜を介して、大きな動力を伝達する。従って、この転がり接触部分、即ち、上記両ディスク２、４の内側面２ａ、４ａと上記各パワーローラ８、８の周面８ａ、８ａとのうち、上記油膜を介して互いに相手面と接触する部分で発生する剪断応力は、一般的な転がり軸受を構成する軌道輪の軌道面或は転動体の転動面で発生する剪断応力に比較して、深い部分にまで達する。従って、上記両ディスク２、４の内側面２ａ、４ａ部分、並びに、上記各パワーローラ８、８の周面８ａ、８ａ部分に形成する硬化層の深さは、一般的な転がり軸受を構成する軌道輪の軌道面部分或は転動体の転動面部分に形成する硬化層よりも深くする必要がある。そして、この為には、上記内側面２ａ、４ａ部分及び周面８ａ、８ａ部分に硬化層を形成する為の浸炭処理又は浸炭窒化処理を、長時間に亙って行なう必要がある。 By the way, the input side and output side disks 2 and 4 and the power rollers 8 and 8 that constitute the toroidal type continuously variable transmission transmit a large amount of power through the oil film at the rolling contact portion with the counterpart member. . Accordingly, the rolling contact portions, that is, the inner surfaces 2a, 4a of the disks 2, 4 and the peripheral surfaces 8a, 8a of the power rollers 8, 8 are in contact with each other through the oil film. The shear stress generated in the portion reaches a deep portion as compared with the shear stress generated on the raceway surface of the bearing ring constituting the general rolling bearing or the rolling surface of the rolling element. Therefore, the depths of the hardened layers formed on the inner side surfaces 2a and 4a of the disks 2 and 4 and the peripheral surfaces 8a and 8a of the power rollers 8 and 8 constitute a general rolling bearing. It is necessary to make it deeper than the hardened layer formed on the raceway surface portion of the raceway or the rolling surface portion of the rolling element. For this purpose, it is necessary to perform a carburizing process or a carbonitriding process for forming a hardened layer on the inner side surfaces 2a, 4a and the peripheral surfaces 8a, 8a for a long time.

この結果、一般的な転がり軸受を構成する軌道輪或は転動体と比較して、熱処理直後の部材表面に、粗大な初析炭化物が生成され易い。特に、図３に於いて丸で囲った上記各部材２、４、８の隅角部（エッジ部）では、素材内部に向けて炭素が、２方向乃至３方向から拡散浸透する為、上記粗大な初析炭化物が生成され易い。この様な粗大な初析炭化物は、割れや亀裂の発生原因となり、上記各部材２、４、８の耐久性低下の原因となる為、好ましくない。尚、動力伝達の際の転がり接触面となる上記各面２ａ、４ａ、８ａは、熱処理後に切削や研削等、必要とする面精度を確保する為に表面を削り取る加工を行なう為、仮に上記熱処理に伴って粗大な初析炭化物が生成されてもこの加工によりこの初析炭化物が除去される為、特に問題を生じない。これに対して、上記隅角部は、コスト低減等の為、上記熱処理後に加工を施さない場合が考えられる。この様な場合には、当該部材の隅角部から、割れや欠け等の損傷が発生する可能性がある。トロイダル型無段変速機は大きな動力を伝達する為、上記各部材２、４、８に入力される力も大きく、上記隅角部に発生した割れや欠け等の損傷が応力集中を引き起こし、当該部材２、４、８全体の割れに進展する可能性もある。 As a result, coarse proeutectoid carbides are likely to be generated on the surface of the member immediately after the heat treatment, compared to a bearing ring or a rolling element constituting a general rolling bearing. In particular, in the corner portions (edge portions) of the members 2, 4, and 8 circled in FIG. 3, carbon diffuses and penetrates from two to three directions toward the inside of the material. New pro-eutectoid carbides are easily generated. Such coarse pro-eutectoid carbides are not preferable because they cause cracks and cracks and cause a decrease in durability of each of the members 2, 4, 8. Each of the surfaces 2a, 4a, 8a, which become rolling contact surfaces during power transmission, is subjected to the above heat treatment in order to perform a process of scraping the surface to ensure the required surface accuracy such as cutting and grinding after the heat treatment. Accordingly, even if coarse pro-eutectoid carbide is produced, this pro-eutectoid carbide is removed by this processing, so that no particular problem occurs. On the other hand, the corner portion may not be processed after the heat treatment in order to reduce costs. In such a case, damages such as cracks and chips may occur from the corners of the member. Since the toroidal continuously variable transmission transmits a large amount of power, the force input to each of the members 2, 4, and 8 is large, and damage such as cracks and chips generated in the corners causes stress concentration. There is also a possibility of progressing to cracks of 2, 4, and 8 as a whole.

この様な不都合を生じる粗大な初析炭化物の析出は、これら各部材２、４、８の隅角部に防炭剤を塗布した状態で上記熱処理を施す事により抑制する事ができる。但し、防炭剤の塗布作業は煩雑であり、上記各部材２、４、８の生産性を低下させる原因となるだけでなく、過って、硬度が必要な上記各面２ａ、４ａ、８ａに防炭剤が付着する可能性を生じる。これら各面２ａ、４ａ、８ａに防炭剤が付着した場合、熱処理を行なっても当該部分に浸炭層や浸炭窒化層が形成されず、必要とされる硬度を得られない。この結果、当該部分の転がり疲れ寿命が確保されず、当該部材２、４、８の耐久性が低下する。 Precipitation of coarse pro-eutectoid carbide that causes such inconvenience can be suppressed by performing the above heat treatment in a state where a carburizing agent is applied to the corners of these members 2, 4, 8. However, the operation of applying the carburizing agent is complicated and not only causes the productivity of the members 2, 4, 8 to be lowered, but also excessively requires the surfaces 2 a, 4 a, 8 a. The possibility of adhering to the carburizing agent is generated. When a carburizing agent adheres to each of these surfaces 2a, 4a, and 8a, even if heat treatment is performed, a carburized layer or a carbonitrided layer is not formed in that portion, and the required hardness cannot be obtained. As a result, the rolling fatigue life of the part is not ensured, and the durability of the members 2, 4, 8 is lowered.

特開２００３−２２２２１６号公報JP 2003-222216 A 特開平９−７９３３７号公報JP-A-9-79337 特開平１０−１０３４４０号公報JP-A-10-103440

本発明は、上述の様な事情に鑑みて、異物が混入したトラクションオイルを使用した場合でも十分な転がり疲れ寿命を確保でき、しかも隅角部に割れや亀裂の発生原因となる粗大な初析炭化物が存在しない入力側、出力側各ディスクやパワーローラを備えたトロイダル型無段変速機を、低コストで実現すべく発明したものである。 In view of the circumstances as described above, the present invention can ensure a sufficient rolling fatigue life even when using traction oil mixed with foreign matters, and also provides a rough initial analysis that causes cracks and cracks in the corners. The present invention has been invented to realize a toroidal-type continuously variable transmission equipped with input side and output side discs and power rollers free of carbides at low cost.

本発明の対象となるトロイダル型無段変速機は、それぞれが鋼製である入力側、出力側両ディスクの、それぞれが断面円弧状の凹面である内側面に、それぞれが鋼製である複数のパワーローラの部分球面状の周面を、トラクションオイルの油膜を介して転がり接触させる事により、上記入力側ディスクと上記出力側ディスクとの間で動力を伝達する。
特に、請求項１に記載したトロイダル型無段変速機に於いては、上記両ディスクと上記各パワーローラとの少なくとも何れかの（好ましくは総ての）部材のうちで、少なくとも隅角部の表面層部分に存在する炭化物の平均粒径が、表面側で小さく、心部に向かう程大きくなる分布を有する。又、上記隅角部に粒径が１０μｍを越える炭化物が存在せず、且つ、上記両ディスクと各パワーローラとの少なくとも何れかの部材の表面のうち、相手部材と転がり接触する面部分の表面からの深さが０．０３mm部分、及び、最大剪断応力位置でのそれぞれのビッカース硬さが、Hv７００以上である。尚、上記表面層とは、転がり疲れ寿命確保の為に必要な硬度を確保すべき部分で、具体的には、当該部材の表面から例えば深さ１．０mmまでの範囲を言う。
又、請求項２に記載したトロイダル型無段変速機の製造方法は、上記両ディスクと上記各パワーローラとの少なくとも何れかの（好ましくは総ての）部材に浸炭処理又は浸炭窒化処理を施す事により、この部材の表面に硬化層を形成する際に、この浸炭処理又は浸炭窒化処理の工程の少なくとも後期を脱炭雰囲気中で行なう事により、上記部材の表面に脱炭層を形成する。 The toroidal-type continuously variable transmission that is the object of the present invention includes a plurality of discs, each of which is made of steel, on the inner surface of each of the input side and output side discs that are made of steel, each of which is a concave surface having an arcuate cross section. Power is transmitted between the input side disk and the output side disk by bringing the partial spherical surface of the power roller into rolling contact with the oil film of traction oil.
In particular, in the toroidal-type continuously variable transmission according to claim 1, of at least one (preferably all) members of both the disks and the power rollers, at least at the corners. The average particle size of the carbides present in the surface layer portion is small on the surface side, and has a distribution that increases toward the core. Further, there is no carbide having a particle size of more than 10 μm in the corner portion, and the surface of the surface portion of the surface of at least one of the disks and the power rollers that is in rolling contact with the mating member The Vickers hardness at a maximum depth of 0.03 mm and the maximum shear stress position is Hv 700 or more. The surface layer is a portion to ensure the hardness necessary for securing the rolling fatigue life, and specifically refers to a range from the surface of the member to a depth of, for example, 1.0 mm.
According to a second aspect of the present invention, there is provided a method for manufacturing a toroidal-type continuously variable transmission, wherein carburizing or carbonitriding is performed on at least one (preferably all) of the disks and the power rollers. Thus, when a hardened layer is formed on the surface of the member, a decarburized layer is formed on the surface of the member by performing at least the latter stage of the carburizing or carbonitriding process in a decarburizing atmosphere.

上述の様に本発明のトロイダル型無段変速機とその製造方法の場合には、異物が混入したトラクションオイルを使用した場合でも十分な転がり疲れ寿命を確保でき、しかも隅角部に割れや亀裂の発生原因となる粗大な初析炭化物が存在しない入力側、出力側各ディスクやパワーローラを備えたトロイダル型無段変速機を、低コストで実現できる。
先ず、両ディスクと各パワーローラとの少なくとも何れかの部材に浸炭処理又は浸炭窒化処理を施す事により、この部材の表面に硬化層を形成している為、この部材表面の残留オーステナイト量を高くして、微小な異物存在下での上記部材の転がり疲れ寿命確保を図れる。 As described above, in the case of the toroidal continuously variable transmission and the manufacturing method thereof according to the present invention, a sufficient rolling fatigue life can be secured even when traction oil mixed with foreign matter is used, and cracks and cracks are formed in the corners. Therefore, a toroidal continuously variable transmission including input and output disks and power rollers that do not include coarse pro-eutectoid carbides that cause generation of low-cost can be realized at low cost.
First, since a hardened layer is formed on the surface of this member by carburizing or carbonitriding at least one member of both disks and each power roller, the amount of retained austenite on the surface of this member is increased. Thus, the rolling fatigue life of the member in the presence of minute foreign matter can be ensured.

又、上記部材の隅角部の表面層部分に存在する炭化物の平均粒径を、表面側で小さくし、更に、この隅角部に、粒径が１０μｍを越える炭化物が存在しない様にしているので、隅角部に割れや亀裂の発生原因となる粗大な初析炭化物が存在しない状態となる。しかも、この状態を造る為に、上記部材に防炭剤を塗布する必要がない為、この部材の製造作業を面倒にしたり、硬度が必要な部分に防炭剤を過って塗布し、この部分の硬度が不足する事も防止できる。この結果、必要とする強度並びに耐久性を備えた入力側、出力側各ディスクやパワーローラを組み込んだトロイダル型無段変速機を、低コストで実現できる。 Further, the average particle size of the carbide existing in the surface layer portion of the corner portion of the member is reduced on the surface side, and further, the carbide having a particle size exceeding 10 μm is not present in the corner portion. Therefore, there is no coarse pro-eutectoid carbide that causes cracks and cracks at the corners. Moreover, in order to create this state, it is not necessary to apply a carburizing agent to the above member, so that the manufacturing work of this member is troublesome, or the carburizing agent is applied over a portion where hardness is required. Insufficient hardness of the part can also be prevented. As a result, a toroidal continuously variable transmission incorporating the input side and output side disks and power rollers having the required strength and durability can be realized at low cost.

浸炭処理又は浸炭窒化処理の終了後に於ける上記両ディスクや上記各パワーローラの表面層部分の炭化物の平均粒径の分布を上述の様にする為には、上記浸炭処理又は浸炭窒化処理の全部又は一部を、脱炭雰囲気中で行なう。この様にして、浸炭初期段階でのカーボンポテンシャル値（ＣＰ値）を高く、浸炭後期段階でのＣＰ値を初期の値よりも下げる事により、上記部材の表面のみを脱炭させる事ができる。尚、この工程により得られる脱炭層の深さは、動力伝達時に相手面とトラクションオイルの油膜を介して転がり接触する面、即ち、図４に破線を付した、上記両ディスク２（４）の内側面２ａ（４ａ）や上記各パワーローラ８の外周面８ａ、更にはスラスト転がり軸受を構成する為に、これら各パワーローラ８の軸方向片面に形成した軌道面１０部分に、浸炭処理又は浸炭窒化処理後に施される仕上加工時の取代を越えない範囲に抑える事が好ましい（請求項３）。上記脱炭層の深さがこの取代を越えた場合には、仕上加工後に、上記転がり接触する面に、硬度が低い、上記脱炭層が残留する。そして、この転がり接触する面に脱炭層が残留する事自体好ましくないが、特にこの様にして残留した脱炭層の厚さが大きいと、上記転がり接触する面の寿命確保が難しくなる。本発明の場合、この転がり接触する面の寿命確保の為に、表面硬さをＨｖ７００以上としている。この様な理由から、上記脱炭層の深さを上記取代以下に抑える事が好ましい。この深さをこの取代以下に抑える限り、上記浸炭処理又は浸炭窒化処理直後の状態で、上記両ディスクや上記各パワーローラの表面層部分の炭化物の平均粒径が、上記隅角部以外で上記分布となる事は差し支えない。 In order to make the distribution of the average particle size of the carbides in the surface layer portions of the disks and the power rollers after the carburizing process or the carbonitriding process complete as described above, the entire carburizing process or carbonitriding process is performed. Or a part is performed in a decarburizing atmosphere. In this way, only the surface of the member can be decarburized by increasing the carbon potential value (CP value) at the initial stage of carburization and lowering the CP value at the later stage of carburization from the initial value. Note that the depth of the decarburized layer obtained by this process is the surface that rolls and contacts the mating surface through the oil film of traction oil during power transmission, that is, the two discs 2 (4) indicated by broken lines in FIG. Carburizing or carburizing is performed on the inner surface 2a (4a), the outer peripheral surface 8a of each power roller 8, and the raceway surface 10 formed on one axial surface of each power roller 8 in order to constitute a thrust rolling bearing. it is preferable to keep the range not exceeding the allowance at the time of finishing to be performed after the nitriding treatment (claim 3). When the depth of the decarburized layer exceeds the allowance, the decarburized layer having a low hardness remains on the surface in contact with the rolling after finishing. Further, it is not preferable that the decarburized layer remains on the surface in contact with the rolling. However, particularly when the thickness of the decarburized layer remaining in this manner is large, it is difficult to ensure the life of the surface in contact with the rolling. In the case of the present invention , the surface hardness is set to Hv 700 or more in order to ensure the life of the rolling contact surface . For this reason, it is preferable to keep the depth of the decarburized layer below the allowance. As long as this depth is kept below this machining allowance, the average particle size of the carbides in the surface layer portions of the disks and the power rollers in the state immediately after the carburizing or carbonitriding process is the above except for the corners. It can be a distribution.

尚、本発明を実施する場合に於いて、上記両ディスクや上記各パワーローラの表面に硬化層を形成する為の熱処理として浸炭窒化処理を採用した場合は、上記脱炭層を形成する為に、処理中におけるＣＰ値を下げる代わりにアンモニア流量を増やす事もできる。この様に、アンモニア流量を増やせば、上記両ディスクや上記各パワーローラの表面の硬度を低下させずに、表面層部分に存在する炭化物の粒径を小さくできる為、好ましい（請求項４）。
又、ＪＩＳ記載の高炭素クロム軸受鋼や炭素工具鋼、合金工具鋼等の素材炭素量が高い鋼材の場合は、浸炭処理又は浸炭窒化処理の際のＣＰ値を素材の炭素含有量よりも下げる事でも、粗大な析出炭化物の析出を抑制する事ができる（請求項５）。 In the case of carrying out the present invention, when carbonitriding is employed as a heat treatment for forming a hardened layer on the surfaces of the disks and the power rollers, in order to form the decarburized layer, Instead of decreasing the CP value during processing, the ammonia flow rate can be increased. Thus, by increasing the ammonia flow rate, without decreasing the hardness of the surface of both the disk and the power rollers, since it reduced the particle size of the carbides present in the surface layer portion, preferably (claim 4).
In addition, in the case of steel materials with a high carbon content such as high carbon chromium bearing steel, carbon tool steel, and alloy tool steel described in JIS, the CP value during carburizing or carbonitriding is lower than the carbon content of the material. even things, can be suppressed precipitation of coarse carbide precipitates (claim 5).

本発明の効果を確認する為に行なった実験に就いて説明する。次の表１に、試料（ディスク及びパワーローラ）の熱処理条件を示す。

An experiment conducted for confirming the effect of the present invention will be described. Table 1 below shows the heat treatment conditions of the samples (disk and power roller).

この表１には、上記試料を作成する為に使用した材料と、浸炭処理或は浸炭窒化処理の際のカーボンポテンシャル値（ＣＰ値）と、浸炭窒化処理の際のアンモニア（ＮＨ₃ ）流量と、熱処理時間とを示した。又、同様に、脱炭工程の際の熱処理条件に就いても記載した。処理温度は、何れの工程に就いても、８４０〜９５０℃とした。又、何れの試料に就いても、脱炭工程終了後に、６０℃の油中で焼き入れ（ズブ焼き入れ）を行なった。又、この焼き入れ後に、１６０〜１８０℃で２時間保持する焼き戻し処理を行なった。更に、これら一連の熱処理（浸炭処理或は浸炭窒化処理→焼き入れ処理→焼き戻し処理）の後、上記各試料のうちで、相手部材と転がり接触する面（図４の破線部分）に仕上加工（切削加工及び研削加工等）を施す事で、これら各試料を目的の形状に仕上げた。又、上記転がり接触する面部分の取代は、０．２mmとした。尚、上記表１に示した１４種類の試料中、実施例１〜４は浸炭処理を、実施例５〜１０は浸炭窒化処理を、それぞれ施したものである。又、このうちの実施例９、１０は、ＪＩＳ鋼種であるＳＵＪ２に、素材中の炭素の炭素含有量（ベースカーボン）よりも低いＣＰ値で浸炭窒化処理を施したものである。更に、比較例１、２は、浸炭処理或は浸炭窒化処理後に脱炭工程を行なわなかったもの、比較例３は、ＳＵＪ２にベースカーボンよりも高いＣＰ値で浸炭窒化した後に脱炭工程を行なわなかったもの、比較例４は、長時間脱炭を行なったものである。 Table 1 shows the material used for preparing the sample, the carbon potential value (CP value) during the carburizing or carbonitriding process, and the ammonia (NH ₃ ) flow rate during the carbonitriding process. The heat treatment time is shown. Similarly, the heat treatment conditions in the decarburization process are also described. The treatment temperature was set to 840 to 950 ° C. in any process. Moreover, in any sample, after completion of the decarburization step, the sample was quenched (oil quenching) in oil at 60 ° C. Further, after this quenching, a tempering treatment was performed by holding at 160 to 180 ° C. for 2 hours. Further, after these series of heat treatments (carburizing or carbonitriding → quenching → tempering), the surface of each of the above samples that is in rolling contact with the mating member (the broken line portion in FIG. 4) is finished. By applying (cutting, grinding, etc.), each of these samples was finished in a desired shape. Moreover, the allowance of the surface part which contacts the said rolling was 0.2 mm. Of the 14 types of samples shown in Table 1, Examples 1 to 4 were subjected to carburizing treatment, and Examples 5 to 10 were subjected to carbonitriding. In Examples 9 and 10, among these, JIS steel type SUJ2 was carbonitrided at a CP value lower than the carbon content (base carbon) of carbon in the material. Further, in Comparative Examples 1 and 2, the decarburization process was not performed after the carburizing process or the carbonitriding process, and in Comparative Example 3, the decarburizing process was performed after carbonitriding SUJ2 with a CP value higher than that of the base carbon. In Comparative Example 4, there was no decarburization for a long time.

この様な条件で作成した、本発明に属する１０種類（実施例１〜１０）と本発明からは外れる４種類（比較例１〜４）との、合計１４種類の試料に関して、それぞれの隅角部の性状と、それぞれの転がり接触する面部分の性状とを測定した。その結果を、次の表２に示す。尚、上記１４種類の試料のそれぞれは、入力側、出力側両ディスクと２個のパワーローラとの組み合わせである。

With respect to a total of 14 types of samples, 10 types (Examples 1 to 10) belonging to the present invention and 4 types (Comparative Examples 1 to 4) outside the present invention, which were created under such conditions, each corner angle. The properties of the parts and the properties of the respective surface portions in contact with the rolling were measured. The results are shown in Table 2 below. Each of the 14 types of samples is a combination of both input and output disks and two power rollers.

この表２には、各試料の隅角部の表面からの深さが０．０５mm部分及び０．２mm部分での炭化物の平均粒径と、転がり接触する面部分の表面からの深さが０．０３mm部分及び１．Ｏmm部分での硬さと、耐久試験の結果とを示した。尚、転がり接触する面部分の表面からの深さが１．Ｏmm部分とは、耐久試験の負荷条件により発生する最大剪断応力位置である。 Table 2 shows that the average particle diameter of carbides in the 0.05 mm portion and the 0.2 mm portion of the depth from the surface of the corner portion of each sample and the depth from the surface of the surface portion in rolling contact are 0. .03mm section and 1. The hardness in the Omm part and the result of the durability test are shown. In addition, the depth from the surface of the surface part which is in rolling contact is 1. The Omm portion is the position of the maximum shear stress generated by the load condition of the durability test.

尚、炭化物の平均粒径の測定は、各試料の隅角部（図３に丸で囲んだ部分）の断面をピクラール（ピクリン酸＋エタノール）で腐食し、表面からの深さが０．０５mm部分及び０．２mm部分のミクロ組織を１０００倍の金属顕微鏡で１０視野観察し、炭化物の粒径を円相当径に換算して平均値を求めた。尚、何れの試料に就いても、隅角部には切削、研削等の仕上加工は施さなかった、従って、上記隅角部の表面とは、熱処理を施された状態のままの表面である。又、１０μｍを超える炭化物の有無に就いては、各試料に存在する総ての隅角部の断面を５００倍の金属顕微鏡で観察し、その有無を確認した。尚、観察は、各隅角部毎に１断面（１視野）ずつとした。又、転がり接触する面部分の硬さ測定は、マイクロビッカース硬さ試験機を使用し、荷重０．９８Ｎ（１００ｇｆ）で測定を行なった。測定は、転がり接触する面部分に就いて、各深さ毎に５点ずつ行ない、その平均値を示した。
The average particle size of the carbide was measured by corroding the cross section of the corner (circled in FIG. 3) of each sample with picral (picric acid + ethanol), and the depth from the surface was 0.05 mm. Ten areas of the microstructure of the portion and the 0.2 mm portion were observed with a 1000 × metal microscope, and the average particle size was determined by converting the particle size of the carbide to the equivalent circle diameter. In any sample, the corner portion was not subjected to finish processing such as cutting and grinding. Therefore, the surface of the corner portion is a surface that has been heat-treated. . Also, concerning the presence or absence of carbide exceeds 10 [mu] m, the cross section of the corner portion of the total hand that exist in each sample was observed at 500 times the metal microscope to confirm the presence or absence. Note that the observation was performed for each cross section (one field of view). Moreover, the hardness of the surface part which carries out rolling contact was measured with a load of 0.98 N (100 gf) using a micro Vickers hardness tester. The measurement was performed on the surface portion in contact with the rolling at five points for each depth, and the average value was shown.

更に、耐久試験は、トロイダル型無段変速機を構成する、動力伝達部のユニットを組み立て、下記の条件で耐久試験を行なった。この耐久試験はこのユニットの何れかの部位に破損を生じるか、或は５０時間を経過するまで行なった。５０時間経過するまで破損なく試験を終了したものを○、それ以外のものを×とした。潤滑油として、実際のトランスミッション各部から出る異物を摸して、鉄粉を混入したトラクションオイルを使用した。
入力側ディスクの回転速度：３５００min^-1 入力側ディスクのトルク：３００Ｎｍ
ユニット部分での変速比：１：１（等速伝達）
潤滑油：市販トラクションオイル
潤滑油供給温度：８０℃
混入異物：粒径が７４〜１４７μｍで硬度がＨｖ８７０の鉄粉を２００ｐｐｍ Furthermore, the durability test assembled the unit of the power transmission part which comprises a toroidal type continuously variable transmission, and performed the durability test on the following conditions. This endurance test was conducted until any part of the unit was damaged or until 50 hours had passed. The test was completed without breakage until 50 hours passed, and the others were marked with x. As the lubricating oil, traction oil mixed with iron powder was used to decease foreign matters from each part of the actual transmission.
Rotation speed of input side disk: 3500 min- ¹ Torque of input side disk: 300 Nm
Gear ratio in the unit part: 1: 1 (constant speed transmission)
Lubricating oil: Commercial traction oil Lubricating oil supply temperature: 80 ° C
Foreign matter: 200 ppm of iron powder having a particle size of 74 to 147 μm and a hardness of Hv870

前記表２の記載から明らかな通り、実施例１〜１０は何れも、熱処理後に行なった脱炭処理の結果、各隅角部で、炭化物の平均粒径が表面側で小さく、心部に向かう程大きくなる分布を有し、しかも、１０μｍを超える粗大な炭化物も見受けられなかった。特に、浸炭窒化処理を施したものは、炭化物の平均粒径が小さくなる傾向が見られた。又、浸炭窒化処理を施す場合には、ＮＨ₃ ガスの流量を増やす事でも、粗大な炭化物の析出を抑制する事ができる事が分かる。更に、相手面と転がり接触する面部分の転がり疲れ寿命（耐久寿命）に就いても、上記実施例１〜１０は何れも、各比較例と同等以上の結果を得られ、粗大な炭化物の生成を抑制する事によっても、上記転がり疲れ寿命が低下しない事が確認された。 As is apparent from the description in Table 2, in each of Examples 1 to 10, as a result of the decarburization treatment performed after the heat treatment, the average particle size of the carbide is small on the surface side at each corner, and heads toward the center. In addition, a coarse carbide exceeding 10 μm was not found. In particular, those subjected to carbonitriding tended to have a smaller average particle size of carbides. It can also be seen that when carbonitriding is performed, precipitation of coarse carbides can be suppressed by increasing the flow rate of NH ₃ gas. Furthermore, even with regard to the rolling fatigue life (durability life) of the surface portion that is in rolling contact with the mating surface, each of the above Examples 1 to 10 can obtain results equivalent to or better than those of the comparative examples, and produce coarse carbides. It was confirmed that the rolling fatigue life does not decrease by suppressing the above.

上述の様な実施例１〜１０に対して、脱炭工程を行なわなかった比較例１〜３は、浸炭処理或は浸炭窒化処理の際のＣＰ値が高く、何れも１０μｍを超える粗大な炭化物が析出した。この様な粗大な炭化物が、亀裂等の損傷の原因となる事は、前述した通りである。一方、脱炭工程の時間を長く、且つＣＰ値を低く設定した比較例４は、脱炭の効果が過剰になって、熱処理後に行なう仕上加工の取代以上の厚さを有する脱炭層が、上記相手面と転がり接触する面部分に形成された為、上記仕上加工後の完成品で、この転がり接触する面部分に脱炭層が残留した。この結果、この転がり接触する面部分の表面から０．０３mmの深さ部分での硬さがＨｖ７００を下回り、この転がり接触する面部分の耐久寿命が、上記各実施例よりも短くなった。 In Comparative Examples 1 to 3 in which the decarburization process was not performed with respect to Examples 1 to 10 as described above, the CP value during the carburizing process or the carbonitriding process is high, and both are coarse carbides exceeding 10 μm. Precipitated. As described above, such coarse carbides cause damage such as cracks. On the other hand, in Comparative Example 4 in which the time of the decarburization step is set long and the CP value is set low, the decarburization effect is excessive, and the decarburization layer having a thickness equal to or greater than the allowance for finishing processing after heat treatment is Since it was formed on the surface portion that was in rolling contact with the mating surface, a decarburized layer remained on the surface portion that was in contact with the rolling in the finished product after the finishing process. As a result, the hardness at a depth portion of 0.03 mm from the surface of the surface portion in contact with the rolling was lower than Hv700, and the durable life of the surface portion in contact with the rolling contact was shorter than that in each of the above examples.

尚、図５に実施例１の、図６に比較例１の、それぞれ隅角部の炭化物の平均粒径の分布を示している。これら図５、６に示した分布曲線は、上記実施例１及び比較例１の隅角部の断面で、表面から０．０５mm、Ｏ．１mm、０．１５mm、Ｏ．２mm、０．５mm部分の深さの数値をグラフにプロットする事により得た。炭化物の平均粒径は、先に述べた通りの方法で測定した。表面から、炭化物の平均粒径の分布が逆転する（当該部分に於ける平均粒径が、この部分よりも深部に存在する炭化物の平均粒径よりも小さくなる＝グラフが左下がりになる起点）部分までの深さを、脱炭深さと言う。図５に示した、上記実施例１の脱炭深さは、０．１５mmである。この図５に示した、上記実施例１の場合には、表面が脱炭されており、炭化物の平均粒径が小さくなっている事が分かる。これに対して、上記図６に示した比較例１の場合、脱炭層は存在しない。 FIG. 5 shows the distribution of the average particle diameters of the carbides at the corners of Example 1 and FIG. 6 of Comparative Example 1, respectively. These distribution curves shown in FIGS. 5 and 6 are cross-sections at the corners of Example 1 and Comparative Example 1, 0.05 mm from the surface, O.D. 1 mm, 0.15 mm, O.D. The values of the depths of 2 mm and 0.5 mm were plotted on a graph. The average particle size of the carbide was measured by the method as described above. From the surface, the distribution of the average particle size of the carbide is reversed (the average particle size in this part is smaller than the average particle size of the carbide existing deeper than this part = the starting point where the graph descends to the left) The depth to the part is called decarburization depth. The decarburization depth of Example 1 shown in FIG. 5 is 0.15 mm. In the case of Example 1 shown in FIG. 5, it can be seen that the surface is decarburized and the average particle size of the carbide is reduced. On the other hand, in the case of the comparative example 1 shown in the said FIG. 6, a decarburization layer does not exist.

この様な脱炭深さは、熱処理後に上記転がり接触する面部分に施す仕上加工時の取代との関係で規制する必要がある。先に説明した各実施例の場合には、この取代を０．２mmとした。仮に取代を０．０５mmにすると、上記実施例１の場合でも、脱炭された部分が上記転がり接触する面部分に残る事になり、この転がり接触する面部分の転がり疲れ寿命に悪影響を及ぼす事になる。従って、脱炭処理の条件は、熱処理後にこの転がり接触する面部分に施す仕上加工の取代によって決める必要があり、好ましくは、上記脱炭層が軌道面表面には含まれない様にして、上記転がり接触する面部分の表面硬さをＨｖ７００以上確保する。
以上に述べた実施例の説明からも明らかな様に、本発明によれば、入力側、出力側各ディスク及びパワーローラに関して、上記転がり接触する面部分の転がり疲れ寿命を確保しつつ、亀裂等の損傷の原因となる、粗大な炭化物の析出を抑制できる。
尚、本発明は、隅角部を有するパワーローラを備えたトロイダル型無段変速機であれば、図示の様なハーフトロイダル型に限らず、フルトロイダル型に対しても適用できる。 Such a decarburization depth needs to be regulated in relation to the machining allowance at the time of finishing applied to the surface portion that comes into contact with rolling after the heat treatment. In the case of each of the embodiments described above, this allowance is set to 0.2 mm. If the machining allowance is 0.05 mm, even in the case of Example 1, the decarburized part remains on the surface part that comes into contact with the rolling, and this has a negative effect on the rolling fatigue life of the surface part that comes in contact with the rolling. become. Therefore, the decarburization conditions need to be determined by the machining allowance for the surface portion that comes into contact with the rolling after the heat treatment. Preferably, the rolling is performed so that the decarburized layer is not included in the raceway surface. The surface hardness of the contacting surface portion is ensured to be Hv 700 or more.
As is clear from the description of the embodiments described above, according to the present invention, the rolling and the like for each of the input side and output side disks and the power roller, while ensuring the rolling fatigue life of the rolling contact surface portion, cracks, etc. It is possible to suppress the precipitation of coarse carbides that cause damage to the steel.
The present invention can be applied not only to the half toroidal type as shown in the figure but also to the full toroidal type as long as it is a toroidal type continuously variable transmission provided with a power roller having a corner portion.

本発明の対象となるトロイダル型無段変速機の基本的構成を、最大減速時の状態で示す側面図。The side view which shows the basic composition of the toroidal type continuously variable transmission used as the object of this invention in the state at the time of maximum deceleration. 同じく最大増速時の状態で示す側面図。The side view similarly shown in the state at the time of maximum acceleration. 粗大な初析炭化物の生成を抑えるべき部分を示す、入力側、出力側両ディスク及びパワーローラの断面図。Sectional drawing of both the input side output disk and a power roller which shows the part which should suppress the production | generation of coarse pro-eutectoid carbide. 運転時に相手面とトラクションオイルの油膜を介して転がり接触する面を示す、入力側、出力側両ディスク及びパワーローラの断面図。Sectional drawing of both the input side and output side discs, and a power roller which show the surface which carries out rolling contact through the oil film of a traction oil at the time of a driving | operation. 実施例１に関して、隅角部の表面からの深さと炭化物の平均粒径との関係を示す線図。FIG. 4 is a diagram showing the relationship between the depth from the surface of the corner portion and the average particle size of carbides in Example 1. 比較例１に関して、隅角部の表面からの深さと炭化物の平均粒径との関係を示す線図。The diagram which shows the relationship between the depth from the surface of a corner part, and the average particle diameter of a carbide | carbonized_material regarding the comparative example 1. FIG.

Explanation of symbols

１入力軸
２入力側ディスク
２ａ内側面
３出力軸
４出力側ディスク
４ａ内側面
５枢軸
６トラニオン
７支持軸
８パワーローラ
８ａ周面
９ローディングカム装置
１０軌道面 DESCRIPTION OF SYMBOLS 1 Input shaft 2 Input side disk 2a Inner side surface 3 Output shaft 4 Output side disk 4a Inner side surface 5 Pivot 6 Trunnion 7 Support shaft 8 Power roller 8a Circumferential surface 9 Loading cam apparatus 10 Track surface

Claims

Each of the input side and output side discs, each made of steel, has a partial spherical peripheral surface of a plurality of power rollers, each made of steel, on the inner side, which is a concave surface with a circular arc cross section. In a toroidal-type continuously variable transmission that transmits power between the input side disk and the output side disk by rolling contact through an oil film, at least one of these disks and each of the power rollers. Among the members, the average particle size of carbides present in at least the surface layer portion of the corner is small on the surface side and has a distribution that increases toward the core, and the particle size exceeds 10 μm in the corner. Carbide does not exist, and the depth from the surface of the surface portion that is in rolling contact with the mating member among the surfaces of at least any of the members of both the disks and the power rollers is 0.03 mm, And the toroidal type continuously variable transmission characterized by each Vickers hardness in the maximum shear stress position being Hv700 or more .

The method for manufacturing a toroidal-type continuously variable transmission according to claim 1, wherein at least one member of both disks and each power roller is subjected to carburizing treatment or carbonitriding treatment so that the surface of the member is cured. A method for manufacturing a toroidal continuously variable transmission, wherein a decarburized layer is formed on the surface of the member by forming at least the latter stage of the carburizing or carbonitriding process in a decarburizing atmosphere when forming the layer.

The depth of the decarburized layer exceeds the machining allowance during finishing, which is applied after carburizing or carbonitriding on the part of the surface of at least one of the disks and each power roller that comes into rolling contact with the mating member. A method for manufacturing a toroidal continuously variable transmission according to claim 2, which is not provided.

A carbonitriding process is adopted as a heat treatment for forming a hardened layer on the surface of at least one member of both disks and each power roller, and a decarburizing atmosphere to be performed at least later in the carbonitriding process is ammonia. The manufacturing method of the toroidal type continuously variable transmission according to any one of claims 2 to 3 , which is realized by increasing the flow rate.

The material constituting at least one of the members of both disks and each power roller is a steel material with a high carbon content, and the carbon potential value during carburizing or carbonitriding is reduced below the carbon content of the material. A method for manufacturing a toroidal continuously variable transmission according to any one of claims 2 to 3 .