JP2024093536A

JP2024093536A - Power transmission shaft

Info

Publication number: JP2024093536A
Application number: JP2022209978A
Authority: JP
Inventors: 健太山崎; 裕一郎北村; 和弘東
Original assignee: NTN Corp
Current assignee: NTN Corp
Filing date: 2022-12-27
Publication date: 2024-07-09

Abstract

The present invention is directed to preventing deterioration in the ease of assembling a blocking member to a hollow shaft.
[Solution] A power transmission shaft (intermediate shaft 4) has a hollow shaft 41 with an inner hole 41a that opens on both axial sides, and a blocking member 42 that blocks the opening of the inner hole 41a of the hollow shaft 41. The hollow shaft 41 has a tapered chamfered portion 41f provided at one axial end of the inner hole 41a, and a cylindrical surface 41g provided on the other axial side of the chamfered portion 41f and into which the blocking member 42 is press-fitted. A relief surface 41h is provided between the chamfered portion 41f and the cylindrical surface 41g, which is recessed toward the outer diameter side from the cylindrical surface 41g.
[Selected figure] Figure 3

Description

本発明は、動力伝達シャフトに関し、特に、中空シャフトとこれに取り付けられた閉塞部材とを有する動力伝達シャフトに関する。 The present invention relates to a power transmission shaft, and in particular to a power transmission shaft having a hollow shaft and a blocking member attached thereto.

例えば、自動車の動力伝達系には、トランスミッションからデファレンシャルギアに動力を伝達するプロペラシャフトや、デファレンシャルギアから駆動輪に動力を伝達するドライブシャフトが設けられる。ドライブシャフトやプロペラシャフトとしては、一対の等速自在継手と、これらを連結する中間シャフトとを有するものが知られている。 For example, the power transmission system of an automobile is provided with a propeller shaft that transmits power from the transmission to a differential gear, and a drive shaft that transmits power from the differential gear to the drive wheels. A known drive shaft or propeller shaft has a pair of constant velocity universal joints and an intermediate shaft that connects them.

ドライブシャフトやプロペラシャフトの中間シャフトとしては、従来から中実シャフトが多く使用されている。しかし、車両の軽量化、ドライブシャフト等の剛性増大による機能向上、曲げ一次固有振動数のチューニングによる車室内の静粛性向上等の観点から、近年では、中間シャフトを中空化する要求が増えてきている（下記の特許文献１参照）。 Solid shafts have traditionally been used widely as intermediate shafts for drive shafts and propeller shafts. However, in recent years, there has been an increasing demand for hollow intermediate shafts in order to reduce the weight of vehicles, improve functionality by increasing the rigidity of drive shafts, and improve cabin quietness by tuning the primary bending natural frequency (see Patent Document 1 below).

また、等速自在継手の外側継手部材は、鍛造等の塑性加工を経て一体成形されることが多い。しかし、左右のドライブシャフトの長さを等しくするために、一方のドライブシャフトのデファレンシャルギア側の外側継手部材の軸部を長くすることがある（このような長尺の軸部を「ロングステム部」と言う。）。このようなロングステム部を有する外側継手部材は、鍛造により一体成形することが困難である。そのため、カップ状のマウス部とロングステム部とを別部材で構成し、両部材を摩擦圧接等により接合することがある（下記の特許文献２参照）。このような外側継手部材のロングステム部においても、自動車の軽量化要求の高まりから、中空化する要求が増えている（例えば、下記の特許文献３の図５参照）。 In addition, the outer joint member of a constant velocity universal joint is often integrally formed through plastic processing such as forging. However, in order to make the lengths of the left and right drive shafts equal, the shaft portion of the outer joint member on the differential gear side of one of the drive shafts may be made longer (such a long shaft portion is called a "long stem portion"). It is difficult to integrally form such an outer joint member having a long stem portion by forging. Therefore, the cup-shaped mouth portion and the long stem portion may be constructed of separate members, and the two members may be joined by friction welding or the like (see Patent Document 2 below). There is also an increasing demand for hollowing out the long stem portion of such outer joint members due to the increasing demand for lighter automobiles (see, for example, Figure 5 of Patent Document 3 below).

ドライブシャフトやプロペラシャフトに設けられた中間シャフトの端部は、グリースが封入された等速自在継手の内部に挿入される。また、ドライブシャフトのインボード側に設けられた等速自在継手の外側継手部材のロングステム部は、デフオイルが封入されたデファレンシャルギアの内部に挿入される。このため、中間シャフトやロングステム部を、軸方向の貫通孔を有する中空シャフトとした場合、中空シャフトの端部の開口部から内孔へグリースやデフオイルが侵入する。このようなグリースやデフオイルの侵入防止を目的として、中空シャフトの内孔の端部に閉塞部材（埋め栓）を取りつけて対処している。 The end of an intermediate shaft attached to a drive shaft or a propeller shaft is inserted into a constant velocity universal joint filled with grease. In addition, the long stem portion of the outer joint member of the constant velocity universal joint attached to the inboard side of the drive shaft is inserted into the inside of a differential gear filled with differential oil. For this reason, if the intermediate shaft or long stem portion is a hollow shaft with an axial through hole, grease and differential oil will enter the inner hole from the opening at the end of the hollow shaft. To prevent such grease and differential oil from entering, a blocking member (fill plug) is attached to the end of the inner hole of the hollow shaft.

中空シャフトに取り付けられる閉塞部材としては、円筒状外周面を有するもの（下記の特許文献１参照）や、樽状外周面を有するもの（下記の特許文献４参照）、あるいは、ゴム等の弾性材料で形成されたもの（下記の特許文献５参照）が知られている。 Known types of closure members that can be attached to hollow shafts include those with a cylindrical outer periphery (see Patent Document 1 below), those with a barrel-shaped outer periphery (see Patent Document 4 below), and those made of an elastic material such as rubber (see Patent Document 5 below).

特開２００７－１００７９８号公報JP 2007-100798 A 特開２０１２－５７６９６号公報JP 2012-57696 A 特開２００７－７５８２４号公報JP 2007-75824 A 特開２０１１－１４４８１７号公報JP 2011-144817 A 特開平６－２８１０１０号公報Japanese Patent Application Laid-Open No. 6-281010

図９に、中空シャフト１０１の端部付近の断面図を示す。中空シャフト１０１の内孔の開口端には、テーパ面状の面取り部１０２が設けられる。この面取り部１０２は、中空シャフト１０１の外周面の旋削やスプライン転造の際に、中空シャフト１０１を芯出しするための支持センターとして使用される。具体的には、中空シャフト１０１の軸端の開口部に円すい状のセンター治具１０３（二点鎖線参照）を挿入し、このセンター治具１０３の外周面を中空シャフト１０１の面取り部１０２に押し付けることで、中空シャフト１０１の芯出しが行われる。このとき、面取り部１０２とこれに連続する円筒面１０４との境界に過大な荷重が加わると、図１０に拡大して示すように、円筒面１０４の端部（面取り部１０２との境界付近）に盛り上がり部１０５が発生することがある。このように、円筒面１０４に盛り上がり部１０５が形成されると、中空シャフト１０１の内孔への閉塞部材１１０の組み付け性に悪影響を与えることが懸念される。 9 shows a cross-sectional view near the end of the hollow shaft 101. A tapered chamfered portion 102 is provided at the open end of the inner hole of the hollow shaft 101. This chamfered portion 102 is used as a support center for centering the hollow shaft 101 when turning the outer circumferential surface of the hollow shaft 101 or rolling the spline. Specifically, a conical center jig 103 (see the two-dot chain line) is inserted into the opening of the shaft end of the hollow shaft 101, and the outer circumferential surface of this center jig 103 is pressed against the chamfered portion 102 of the hollow shaft 101, thereby centering the hollow shaft 101. At this time, if an excessive load is applied to the boundary between the chamfered portion 102 and the cylindrical surface 104 that is continuous with it, a bulge 105 may be generated at the end of the cylindrical surface 104 (near the boundary with the chamfered portion 102), as shown in an enlarged view in FIG. 10. In this way, if a raised portion 105 is formed on the cylindrical surface 104, there is a concern that this will adversely affect the ease of assembling the blocking member 110 into the inner hole of the hollow shaft 101.

例えば、図９に点線で示すように面取り部１０２’を大きくすることで、センター治具１０３と面取り部１０２’との面圧を下げて、盛り上がり部を抑制することも考えられる。しかし、面取り部１０２’を大きくすると、中間シャフト１０１の端面１０６の面積が減少するため、端面１０６を基準として加工する際に不具合が生じる恐れがある。 For example, as shown by the dotted line in FIG. 9, by enlarging the chamfered portion 102', it is possible to reduce the surface pressure between the center jig 103 and the chamfered portion 102' and suppress the protruding portion. However, if the chamfered portion 102' is enlarged, the area of the end face 106 of the intermediate shaft 101 will decrease, which may cause problems when machining using the end face 106 as a reference.

そこで、本発明は、中空シャフトに対する閉塞部材の組み付け性の低下を防止することを目的とする。 Therefore, the present invention aims to prevent a decrease in the ease of assembling the blocking member to the hollow shaft.

前記課題を解決するために、本発明は、少なくとも軸方向一方側に開口した内孔を有する中空シャフトと、前記中空シャフトの前記内孔の軸方向一方側の開口部を閉塞する閉塞部材とを有し、
前記中空シャフトが、前記内孔の軸方向一方の端部に設けられたテーパ面状の面取り部と、前記面取り部の軸方向他方側に設けられ、前記閉塞部材が圧入される円筒面とを有する動力伝達シャフトであって、
前記面取り部と前記円筒面との間に、前記円筒面よりも外径側に後退した逃げ面を設けたことを特徴とする。 In order to solve the above problem, the present invention provides a hollow shaft having an inner hole that opens to at least one axial side, and a closing member that closes an opening on one axial side of the inner hole of the hollow shaft,
the hollow shaft is a power transmission shaft having a tapered chamfered portion provided at one axial end of the inner hole, and a cylindrical surface provided on the other axial side of the chamfered portion and into which the blocking member is press-fitted,
The present invention is characterized in that a relief surface is provided between the chamfered portion and the cylindrical surface, the relief surface being recessed radially outward from the cylindrical surface.

このように、本発明では、中空シャフトの内周面の面取り部と円筒面との間に逃げ面を設けた。この場合、センター治具を面取り部に押し付けることにより、中空シャフトの内周面に盛り上がり部が形成されたとしても、その盛り上がり部は、閉塞部材が圧入される円筒面ではなく、円筒面よりも外径側に後退した逃げ面に形成される。これにより、盛り上がり部が円筒面よりも内径側に突出する量を低減あるいは０にすることができるため、盛り上がり部が閉塞部材の組み付けを阻害する事態を回避できる。 In this way, in the present invention, a relief surface is provided between the chamfered portion on the inner peripheral surface of the hollow shaft and the cylindrical surface. In this case, even if a raised portion is formed on the inner peripheral surface of the hollow shaft by pressing the center jig against the chamfered portion, the raised portion is formed on the relief surface that is recessed toward the outer diameter side from the cylindrical surface, not on the cylindrical surface into which the blocking member is pressed. This makes it possible to reduce or eliminate the amount by which the raised portion protrudes toward the inner diameter side from the cylindrical surface, thereby avoiding a situation in which the raised portion impedes the assembly of the blocking member.

上記の動力伝達シャフトでは、逃げ面を、軸方向一方側に行くにつれて拡径したテーパ面状に形成することができる。この場合、逃げ面の軸方向に対する傾斜角度は、面取り部の軸方向に対する傾斜角度よりも小さいことが好ましく、例えば、１°～５°とすることができる。 In the above power transmission shaft, the relief surface can be formed into a tapered surface shape that widens in diameter toward one side in the axial direction. In this case, the inclination angle of the relief surface relative to the axial direction is preferably smaller than the inclination angle of the chamfered portion relative to the axial direction, and can be, for example, 1° to 5°.

あるいは、逃げ面を、軸方向一方側に行くにつれて拡径した凹曲面状に形成することもできる。 Alternatively, the relief surface can be formed as a concave curved surface that widens in diameter toward one side in the axial direction.

上記の動力伝達シャフトでは、面取り部と逃げ面との境界における直径Ｄｉｔと、円筒面の内径Ｄｉとが、Ｄｉｔ＞Ｄｉ＋０．１ｍｍを満たすことが好ましい。 In the above power transmission shaft, it is preferable that the diameter Dit at the boundary between the chamfered portion and the flank face and the inner diameter Di of the cylindrical surface satisfy Dit > Di + 0.1 mm.

中空シャフトの内周面に、前記円筒面の軸方向他方側に設けられ、前記円筒面よりも小径な小径円筒面と、前記円筒面と前記小径円筒面とを繋ぐ段差部とを設け、前記段差部を前記閉塞部材と軸方向で当接させてもよい。このように、中空シャフトの内周面に形成した段差部に閉塞部材を軸方向で当接させることで、中空シャフトに対して閉塞部材を軸方向で位置決めすることができる。 The inner circumferential surface of the hollow shaft may be provided on the other axial side of the cylindrical surface with a small diameter cylindrical surface smaller than the cylindrical surface, and a step portion connecting the cylindrical surface and the small diameter cylindrical surface may be provided, and the step portion may be abutted against the blocking member in the axial direction. In this way, by abutting the blocking member in the axial direction against the step portion formed on the inner circumferential surface of the hollow shaft, the blocking member can be positioned in the axial direction relative to the hollow shaft.

上記の動力伝達シャフトは、例えばドライブシャフトの中間シャフトとして用いることができる。具体的には、上記の動力伝達シャフトと、この動力伝達シャフトの両端に取り付けられた一対の等速自在継手とを備えたドライブシャフトを得ることができる。 The above-mentioned power transmission shaft can be used, for example, as an intermediate shaft of a drive shaft. Specifically, a drive shaft can be obtained that includes the above-mentioned power transmission shaft and a pair of constant velocity universal joints attached to both ends of the power transmission shaft.

あるいは、上記の動力伝達シャフトは、外側継手部材のロングステム部として用いることができる。具体的には、上記の動力伝達シャフトと、この動力伝達シャフトの軸方向他方の端部に接合されたカップ状のマウス部とを有する外側継手部材を得ることができる。 Alternatively, the power transmission shaft can be used as the long stem portion of the outer joint member. Specifically, an outer joint member can be obtained that has the power transmission shaft and a cup-shaped mouth portion joined to the other axial end of the power transmission shaft.

以上のように、本発明の動力伝達シャフトによれば、中空シャフトの内周面に形成される盛り上がり部により閉塞部材の組み付け性が低下する事態を防止できる。 As described above, the power transmission shaft of the present invention can prevent a situation in which the mounting of the blocking member is impaired due to a raised portion formed on the inner peripheral surface of the hollow shaft.

本発明の第１実施形態に係る動力伝達シャフトとしての中間シャフトを有するドライブシャフトの軸方向断面図である。1 is an axial cross-sectional view of a drive shaft having an intermediate shaft as a power transmission shaft according to a first embodiment of the present invention. FIG. 上記中間シャフトの軸方向断面図である。FIG. 4 is an axial cross-sectional view of the intermediate shaft. 図２の中空シャフトのアウトボード側端部周辺の拡大図である。FIG. 3 is an enlarged view of the outboard end portion of the hollow shaft of FIG. 2 . （Ａ）～（Ｄ）は、上記中空シャフトの加工工程を示す軸方向断面図である。11A to 11D are axial cross-sectional views showing the machining process of the hollow shaft. 本発明の第２実施形態に係る中空シャフトの端部周辺の軸方向断面図である。6 is an axial cross-sectional view of the periphery of an end portion of a hollow shaft according to a second embodiment of the present invention. FIG. 本発明の第３実施形態に係る中空シャフトの端部周辺の軸方向断面図である。10 is an axial cross-sectional view of the periphery of an end portion of a hollow shaft according to a third embodiment of the present invention. FIG. 本発明の第４実施形態に係る動力伝達シャフトとしてのロングステム部を有する外側継手部材の軸方向断面図である。FIG. 11 is an axial cross-sectional view of an outer joint member having a long stem portion as a power transmission shaft according to a fourth embodiment of the present invention. 図７のロングステム部の端部周辺の軸方向断面図である。8 is an axial cross-sectional view of the end portion of the long stem portion of FIG. 7 . FIG. 従来の中空シャフトの端部周辺の軸方向断面図である。1 is an axial cross-sectional view of the vicinity of an end portion of a conventional hollow shaft. 図９のＡ部の拡大図である。FIG. 10 is an enlarged view of part A in FIG. 9 .

以下、本発明の第１実施形態を、図１～４に基づいて説明する。 The first embodiment of the present invention will be described below with reference to Figures 1 to 4.

図１に、自動車のデファレンシャルギアと車輪とを接続するドライブシャフト１を示す。ドライブシャフト１は、アウトボード側（車幅方向外側、図１の左側）に設けられた固定式等速自在継手２と、インボード側（車幅方向中央側、図１の右側）に設けられた摺動式等速自在継手３と、両等速自在継手２、３を連結する中間シャフト４とを備える。中間シャフト４が、本発明の一実施形態に係る動力伝達シャフトに相当する。 Figure 1 shows a drive shaft 1 that connects the differential gear and wheels of an automobile. The drive shaft 1 is equipped with a fixed constant velocity universal joint 2 provided on the outboard side (outside in the vehicle width direction, left side in Figure 1), a sliding constant velocity universal joint 3 provided on the inboard side (center in the vehicle width direction, right side in Figure 1), and an intermediate shaft 4 that connects both constant velocity universal joints 2, 3. The intermediate shaft 4 corresponds to a power transmission shaft in one embodiment of the present invention.

固定式等速自在継手２は、ツェッパ型と称されるものであり、外側継手部材２１と、内側継手部材２２と、トルク伝達部材としての複数のボール２３と、保持器２４とを有する。外側継手部材２１の内球面に形成された複数のトラック溝２１ａと、内側継手部材２２の外球面に形成された複数のトラック溝２２ａとで複数のボールトラックが形成され、各ボールトラックにボール２３が一個ずつ配される。外側継手部材２１と内側継手部材２２との間で、角度変位を許容しながら、ボール２３を介してトルクが等速で伝達される。外側継手部材２１のステム部２１ｂは、図示しない車輪用軸受を介して車輪と連結される。尚、固定式等速自在継手２は上記に限らず、例えば、トラック溝２１ａ、２２ａの一部を直線状としたアンダーカットフリー型や、対向するトラック溝２１ａ、２２ａを、外周側から見て互いに交差するように傾斜させたクロスグルーブ型であってもよい。 The fixed constant velocity universal joint 2 is called a Rzeppa type, and has an outer joint member 21, an inner joint member 22, a plurality of balls 23 as torque transmission members, and a cage 24. A plurality of track grooves 21a formed on the inner spherical surface of the outer joint member 21 and a plurality of track grooves 22a formed on the outer spherical surface of the inner joint member 22 form a plurality of ball tracks, and one ball 23 is arranged on each ball track. Between the outer joint member 21 and the inner joint member 22, torque is transmitted at a constant speed through the balls 23 while allowing angular displacement. The stem portion 21b of the outer joint member 21 is connected to a wheel via a wheel bearing (not shown). The fixed constant velocity universal joint 2 is not limited to the above, and may be, for example, an undercut-free type in which part of the track grooves 21a, 22a are linear, or a cross-groove type in which the opposing track grooves 21a, 22a are inclined so as to intersect with each other when viewed from the outer periphery.

摺動式等速自在継手３は、トリポード型と称されるものであり、外側継手部材３１と、内側継手部材（トリポード部材）３２と、トルク伝達部材としての複数のローラ３３とを有する。内側継手部材３２に設けられた３本の脚軸３２ａの外周に、ローラ３３が針状ころを介して配される。外側継手部材３１の内周面に形成された複数のトラック溝３１ａに、ローラ３３が配される。外側継手部材３１と内側継手部材３２との間で、角度変位及び軸方向変位を許容しながら、ローラ３３を介してトルクが等速で伝達される。外側継手部材３１のステム部３１ｂは、図示しないデファレンシャルギアに連結される。尚、摺動式等速自在継手３は上記に限らず、例えば、トルク伝達部材としてボールを用いたもの（ダブルオフセット型等）であってもよい。 The sliding constant velocity universal joint 3 is called a tripod type and has an outer joint member 31, an inner joint member (tripod member) 32, and multiple rollers 33 as torque transmission members. The rollers 33 are arranged on the outer periphery of three pedestals 32a provided on the inner joint member 32 via needle rollers. The rollers 33 are arranged in multiple track grooves 31a formed on the inner peripheral surface of the outer joint member 31. Torque is transmitted at a constant speed between the outer joint member 31 and the inner joint member 32 via the rollers 33 while allowing angular displacement and axial displacement. The stem portion 31b of the outer joint member 31 is connected to a differential gear (not shown). The sliding constant velocity universal joint 3 is not limited to the above, and may be, for example, one that uses balls as torque transmission members (double offset type, etc.).

中間シャフト４は、内孔４１ａを有する中空シャフト４１と、中空シャフト４１の内孔４１ａの開口部を閉塞する閉塞部材４２とを有する。図示例では、中空シャフト４１の内孔４１ａが、中空シャフト４１を軸方向に貫通して軸方向両側に開口し、それぞれの開口部に閉塞部材４２が装着されている。中空シャフト４１は、軸方向中間部に設けられた大径部４１ｂと、その軸方向両側に設けられた小径部４１ｃとを有する。中空シャフト４１の外周面の軸方向両端付近には、雄スプライン４１ｄと、環状の止め輪溝４１ｅが形成される（図２参照）。中空シャフト４１のうち、軸方向両端の止め輪溝４１ｅの軸方向間領域には、後述する熱処理工程による硬化層（図２の散点領域）が形成されている。 The intermediate shaft 4 has a hollow shaft 41 having an inner hole 41a and a blocking member 42 that blocks the opening of the inner hole 41a of the hollow shaft 41. In the illustrated example, the inner hole 41a of the hollow shaft 41 penetrates the hollow shaft 41 in the axial direction and opens on both axial sides, and a blocking member 42 is attached to each opening. The hollow shaft 41 has a large diameter portion 41b provided in the axial middle portion and a small diameter portion 41c provided on both axial sides. A male spline 41d and an annular retaining ring groove 41e are formed near both axial ends of the outer circumferential surface of the hollow shaft 41 (see FIG. 2). A hardened layer (scattered area in FIG. 2) is formed by a heat treatment process described later in the axial region between the retaining ring grooves 41e at both axial ends of the hollow shaft 41.

中空シャフト４１の両端は、それぞれ両等速自在継手２、３の内側継手部材２２、３２の内周に挿入される（図１参照）。中空シャフト４１の両端の雄スプライン４１ｄと内側継手部材２２、３２の内周に形成された雌スプラインとを嵌合させることにより、これらがトルク伝達可能に連結される。中空シャフト４１の止め輪溝４１ｅに装着された止め輪を、内側継手部材２２、３２と軸方向で係合させることで、中空シャフト４１に対する内側継手部材２２、３２の軸方向の抜け止めが行われる。 The ends of the hollow shaft 41 are inserted into the inner circumferences of the inner joint members 22, 32 of the constant velocity universal joints 2, 3 (see Figure 1). The male splines 41d at both ends of the hollow shaft 41 are fitted into the female splines formed on the inner circumferences of the inner joint members 22, 32, so that they are connected to transmit torque. The retaining rings attached to the retaining ring grooves 41e of the hollow shaft 41 are engaged in the axial direction with the inner joint members 22, 32 to prevent the inner joint members 22, 32 from coming loose in the axial direction from the hollow shaft 41.

図３に、中空シャフト４１のアウトボード側の端部付近の軸方向断面図を示す。中空シャフト４１の内孔４１ａには、軸方向端部に設けられた面取り部４１ｆと、面取り部４１ｆから反軸端側（図３の右側）に離間して設けられた円筒面４１ｇと、面取り部４１ｆと円筒面４１ｇとの間に設けられた逃げ面４１ｈとが形成される。面取り部４１ｆは、軸端側（図３の左側）に行くにつれて拡径した傾斜面であり、図示例では、軸方向に対して角度α（例えば４５°）で傾斜したテーパ面で構成される。尚、図３では、中空シャフト４１のアウトボード側（図１、２の左側）の端部を拡大して示しているが、中空シャフト４１のインボード側（図１、２の右側）の端部にも、上記と同様に面取り部４１ｆ、円筒面４１ｇ、及び逃げ面４１ｈが形成される。 Figure 3 shows an axial cross-sectional view of the hollow shaft 41 near the outboard end. The inner hole 41a of the hollow shaft 41 has a chamfered portion 41f at the axial end, a cylindrical surface 41g spaced from the chamfered portion 41f toward the opposite axial end (right side of Figure 3), and a relief surface 41h between the chamfered portion 41f and the cylindrical surface 41g. The chamfered portion 41f is an inclined surface that increases in diameter toward the axial end (left side of Figure 3), and in the illustrated example, is composed of a tapered surface inclined at an angle α (for example, 45°) with respect to the axial direction. Note that Figure 3 shows an enlarged view of the outboard end (left side of Figures 1 and 2) of the hollow shaft 41, but the inboard end (right side of Figures 1 and 2) of the hollow shaft 41 also has a chamfered portion 41f, a cylindrical surface 41g, and a relief surface 41h formed in the same manner as described above.

逃げ面４１ｈは、円筒面４１ｇよりも外径側に後退している。詳しくは、面取り部４１ｆの反軸端側の端部における直径Ｄｉｔが、円筒面４１ｇの内径Ｄｉよりも僅かに大きくなっており、逃げ面４１ｈがこれらを繋いでいる。図示例では、逃げ面４１ｈが、軸端側に行くにつれて徐々に拡径した面であり、具体的には、軸端側に行くにつれて拡径したテーパ面状に形成される。逃げ面４１ｈの軸方向に対する傾斜角度θは、面取り部４１ｆの軸方向に対する傾斜角度αよりも小さく、具体的には１°～５°とされ、例えば３°とされる。 The relief surface 41h is set back toward the outer diameter side from the cylindrical surface 41g. More specifically, the diameter Dit at the end of the chamfered portion 41f on the opposite axial end side is slightly larger than the inner diameter Di of the cylindrical surface 41g, and the relief surface 41h connects them. In the illustrated example, the relief surface 41h is a surface whose diameter gradually increases toward the axial end side, and more specifically, is formed into a tapered surface whose diameter increases toward the axial end side. The inclination angle θ of the relief surface 41h with respect to the axial direction is smaller than the inclination angle α of the chamfered portion 41f with respect to the axial direction, and is specifically set to 1° to 5°, for example 3°.

閉塞部材４２は、筒部４２ａと、筒部４２ａの軸方向一方の端部を閉塞する底部４２ｂとを一体に有するカップ状を成している。図示例では、筒部４２ａが円筒状に形成される。閉塞部材４２は、金属、例えば鋼材で形成される。閉塞部材４２の筒部４２ａの外周面は、中空シャフト４１の円筒面４１ｇに圧入されている。閉塞部材４２は、軸方向内側に底部４２ｂが配され、軸方向外側に向けて開口する向きで、中間シャフト４１に取り付けられる。 The blocking member 42 is cup-shaped and integrally comprises a tubular portion 42a and a bottom portion 42b that blocks one axial end of the tubular portion 42a. In the illustrated example, the tubular portion 42a is formed in a cylindrical shape. The blocking member 42 is formed of metal, for example, steel. The outer peripheral surface of the tubular portion 42a of the blocking member 42 is press-fitted into the cylindrical surface 41g of the hollow shaft 41. The blocking member 42 is attached to the intermediate shaft 41 with the bottom portion 42b disposed on the axial inner side and open toward the axial outer side.

以下、中間シャフト４の製造方法を、中空シャフト４１の加工方法を中心に詳しく説明する。 The manufacturing method for the intermediate shaft 4 will be explained in detail below, focusing on the processing method for the hollow shaft 41.

中空シャフト４１は、絞り工程、旋削工程、転造工程、熱処理工程を経て製造される。 The hollow shaft 41 is manufactured through a drawing process, a turning process, a rolling process, and a heat treatment process.

絞り工程では、パイプ状の素材に絞り加工を施して、大径部及びその軸方向両側に設けられた小径部４１ｃ’を有する中空シャフト素材４１’｛図４（Ａ）参照｝を形成する。絞り工程が施された中空シャフト素材４１’の小径部４１ｃ’の内周面には、円筒面４１ｇが形成されている。尚、円筒面４１ｇの軸方向両端付近を除く中間領域（後述する旋削工程が施されない軸方向領域）は、その後の工程で加工されないため、絞り加工により形成された面の状態で完成品の中間シャフト４１に残る。 In the drawing process, a pipe-shaped material is drawn to form a hollow shaft material 41' (see FIG. 4(A)) having a large diameter portion and small diameter portions 41c' on both axial sides of the large diameter portion. A cylindrical surface 41g is formed on the inner peripheral surface of the small diameter portion 41c' of the hollow shaft material 41' that has been drawn. Note that the intermediate region (the axial region not subjected to the turning process described below) excluding the vicinity of both axial ends of the cylindrical surface 41g is not machined in the subsequent process, and therefore remains in the finished intermediate shaft 41 in the form of the surface formed by the drawing process.

旋削工程は、中空シャフト素材４１’の内周面の端部付近を旋削する内周旋削工程と、中空シャフト素材４１’の外周面の所定部位を旋削する外周旋削工程とを有する。 The turning process includes an inner turning process in which the inner surface of the hollow shaft material 41' near the end is turned, and an outer turning process in which a predetermined portion of the outer surface of the hollow shaft material 41' is turned.

内周旋削工程では、中空シャフト素材４１’に対して相対回転する切削刃により、中空シャフト素材４１’の内周面の軸方向両端付近に面取り部４１ｆ及び逃げ面４１ｈを形成する｛図４（Ｂ）参照｝。 In the inner peripheral turning process, a cutting blade that rotates relative to the hollow shaft blank 41' forms chamfered portions 41f and relief surfaces 41h near both axial ends of the inner peripheral surface of the hollow shaft blank 41' (see FIG. 4B).

その後の外周旋削工程では、まず、図４（Ｃ）に示すように、中空シャフト素材４１の内孔に軸方向両側から円すい形状のセンター治具５０を挿入し、センター治具５０のテーパ面状外周面を、内周旋削工程で形成された中空シャフト素材の面取り部４１ｆに押し付けることにより、中空シャフト素材の芯出しを行う。この状態で、中空シャフト素材を回転させながら、中空シャフト素材の外周面の所定部位に切削刃を押し当てることにより、雄スプライン４１ｄの下径（転造下径）となる円筒面４１ｄ’、止め輪溝４１ｅ、外周面の軸方向端部の面取り部４１ｋが形成される。 In the subsequent outer peripheral turning process, first, as shown in FIG. 4(C), a conical center jig 50 is inserted into the inner hole of the hollow shaft material 41 from both axial sides, and the tapered outer peripheral surface of the center jig 50 is pressed against the chamfered portion 41f of the hollow shaft material formed in the inner peripheral turning process to center the hollow shaft material. In this state, while rotating the hollow shaft material, a cutting blade is pressed against a predetermined portion of the outer peripheral surface of the hollow shaft material, forming a cylindrical surface 41d' that becomes the lower diameter (rolling lower diameter) of the male spline 41d, a retaining ring groove 41e, and a chamfered portion 41k at the axial end of the outer peripheral surface.

転造工程では、まず、上記の外周旋削工程と同様に、中空シャフト素材４１’の内孔に軸方向両側から円すい形状のセンター治具を挿入して、中空シャフト素材４１’の芯出しを行う。この状態で、中空シャフト素材４１’の外周面の軸方向両端付近に転造加工を施すことにより、雄スプライン４１ｄが形成される｛図４（Ｄ）参照｝。 In the rolling process, first, as in the outer peripheral turning process described above, a conical center jig is inserted into the inner hole of the hollow shaft material 41' from both axial sides to center the hollow shaft material 41'. In this state, rolling is performed near both axial ends of the outer peripheral surface of the hollow shaft material 41' to form male splines 41d (see Figure 4 (D)).

上記の外周旋削工程や転造工程において、センター治具５０を中空シャフト素材の面取り部４１ｆに押し付けることにより、面取り部４１ｆの軸方向内側に隣接する領域に、内径側に盛り上がった盛り上がり部が形成されることがある（図１０参照）。このような盛り上がり部が円筒面４１ｇに形成されると、後述する閉塞部材４２の圧入行程が阻害される恐れがある。本実施形態では、面取り部４１ｆと円筒面４１ｇとの間に、円筒面４１ｇよりも外径側に後退した逃げ面４１ｈを設けることで、盛り上がり部が逃げ面４１ｈに形成されるようにした。これにより、盛り上がり部が円筒面４１ｇから内径側に突出しないようにすることができ、あるいは、突出したとしてもその突出量を低減することができるため、後述する閉塞部材４２の圧入行程が盛り上がり部により阻害される事態を防止できる。 In the above outer peripheral turning process and rolling process, by pressing the center jig 50 against the chamfered portion 41f of the hollow shaft material, a raised portion may be formed on the inner diameter side in the area adjacent to the axial inside of the chamfered portion 41f (see FIG. 10). If such a raised portion is formed on the cylindrical surface 41g, there is a risk that the press-in process of the blocking member 42 described later will be hindered. In this embodiment, a relief surface 41h is provided between the chamfered portion 41f and the cylindrical surface 41g, which is recessed toward the outer diameter side from the cylindrical surface 41g, so that the raised portion is formed on the relief surface 41h. This makes it possible to prevent the raised portion from protruding from the cylindrical surface 41g to the inner diameter side, or, even if it does protrude, the amount of protrusion can be reduced, so that the situation in which the press-in process of the blocking member 42 described later is hindered by the raised portion can be prevented.

上記の盛り上がり部の逃げ面４１ｈに対する半径方向の突出量は、中空シャフト４１の材質やセンター治具５０の押し付け力等により異なるが、通常、最大でも５０μｍ程度である。この観点から、面取り部４１ｆと逃げ面４１ｈとの境界における直径Ｄｉｔと円筒面４１ｇの内径Ｄｉは、Ｄｉｔ＞Ｄｉ＋０．１ｍｍを満たすようにしておけば、盛り上がり部が円筒面４１ｇよりも内径側に突出する事態を回避できる。 The amount of radial protrusion of the raised portion from the flank 41h varies depending on the material of the hollow shaft 41 and the pressing force of the center jig 50, but is usually at most about 50 μm. From this perspective, if the diameter Dit at the boundary between the chamfered portion 41f and the flank 41h and the inner diameter Di of the cylindrical surface 41g are set to Dit > Di + 0.1 mm, it is possible to avoid the raised portion protruding toward the inner diameter side of the cylindrical surface 41g.

熱処理工程では、中空シャフト素材の外周面の所定領域に焼き入れ焼き戻し処理が施される。本実施形態では、図２に示すように、中空シャフト素材の外周面のうち、止め輪溝４１ｅよりも軸方向内側の領域に熱処理が施される。図示例では、熱処理による硬化層が中空シャフト４１の内周面まで達している。これに限らず、熱処理による硬化層が中空シャフト４１の内周面まで達しないようにして、内周面を非熱処理面（生材からなる面）としてもよい。 In the heat treatment process, a quenching and tempering process is performed on a predetermined region of the outer circumferential surface of the hollow shaft material. In this embodiment, as shown in FIG. 2, heat treatment is performed on a region of the outer circumferential surface of the hollow shaft material that is axially inward of the retaining ring groove 41e. In the illustrated example, the hardened layer formed by the heat treatment reaches the inner circumferential surface of the hollow shaft 41. However, the hardened layer formed by the heat treatment may not reach the inner circumferential surface of the hollow shaft 41, and the inner circumferential surface may be a non-heat treated surface (a surface made of raw material).

以上の工程を経て製造された中空シャフト４１に、閉塞部材４２を圧入する。具体的に、中空シャフト４１に組み付ける前の状態では、閉塞部材４２の筒部４２ａの外径が、中空シャフト４１の円筒面４１ｇの内径Ｄｉよりも僅かに大きく設定されている。この閉塞部材４２を弾性変形させながら中空シャフト４１の内周に押し込んで、円筒面４１ｇの内周に配することにより、閉塞部材４２の筒部４２ａの外周面と中空シャフト４１の円筒面４１ｇとが締め代をもって嵌合する。 The blocking member 42 is press-fitted into the hollow shaft 41 manufactured through the above steps. Specifically, before being assembled to the hollow shaft 41, the outer diameter of the tubular portion 42a of the blocking member 42 is set to be slightly larger than the inner diameter Di of the cylindrical surface 41g of the hollow shaft 41. The blocking member 42 is elastically deformed while being pressed into the inner circumference of the hollow shaft 41 and placed on the inner circumference of the cylindrical surface 41g, so that the outer peripheral surface of the tubular portion 42a of the blocking member 42 and the cylindrical surface 41g of the hollow shaft 41 fit together with a tightening margin.

このとき、上述の外周旋削工程で発生した盛り上がり部が、円筒面４１ｇよりも外径側に後退した逃げ面４１ｈに形成されているため、閉塞部材４２の円筒面４１ｇへの圧入が盛り上がり部により阻害される事態を防止できる。 At this time, the raised portion generated in the outer peripheral turning process described above is formed on the clearance surface 41h, which is recessed toward the outer diameter side from the cylindrical surface 41g, so that the raised portion can be prevented from impeding the press-fitting of the blocking member 42 into the cylindrical surface 41g.

本発明は上記の実施形態に限られない。以下、本発明の他の実施形態を説明するが、上記の実施形態と同様の点については重複説明を省略する。 The present invention is not limited to the above embodiment. Other embodiments of the present invention will be described below, but duplicate explanations of points similar to the above embodiment will be omitted.

図５に示す第２実施形態では、逃げ面４１ｈが、面取り部４１ｆと円筒面４１ｇとを直線的につなぐテーパ面（図３参照）よりも外径側に膨出した凹曲面状に形成される。図示例では、逃げ面４１ｈが、曲率半径Ｒの断面円弧状の凹曲面で構成される。逃げ面４１ｈは、軸方向外側に行くにつれて徐々に大径になっている。図示例では、断面円弧状の逃げ面４１ｈの曲率中心が、面取り部４１ｆと逃げ面４１ｈとの境界と同じ軸方向位置に配される。尚、断面円弧状の逃げ面４１ｈの曲率中心を、面取り部４１ｆと逃げ面４１ｈとの境界よりも軸方向外側（図５の左側）に設けてもよい。また、逃げ面４１ｈの軸方向断面を、楕円形状等の非円弧形状の曲線としてもよい。 In the second embodiment shown in FIG. 5, the flank 41h is formed as a concave curved surface that bulges outward from the tapered surface (see FIG. 3) that linearly connects the chamfered portion 41f and the cylindrical surface 41g. In the illustrated example, the flank 41h is configured as a concave curved surface that is arc-shaped in cross section with a curvature radius R. The flank 41h gradually becomes larger in diameter as it goes axially outward. In the illustrated example, the center of curvature of the arc-shaped flank 41h is located in the same axial position as the boundary between the chamfered portion 41f and the flank 41h. The center of curvature of the arc-shaped flank 41h may be located axially outward (left side in FIG. 5) from the boundary between the chamfered portion 41f and the flank 41h. The axial cross section of the flank 41h may also be a curved line that is non-arc-shaped, such as an elliptical shape.

逃げ面４１ｈの形状は上記に限らず、例えば、逃げ面４１ｈを、円筒面４１ｇと平行で、且つ、円筒面４１ｇよりも大径な大径円筒面で構成してもよい（図示省略）。この場合、円筒面４１ｇと逃げ面４１ｈ（大径円筒面）との間に、これらを繋ぐ段差部（例えば、軸方向と直交する平坦面）が形成される。 The shape of the relief surface 41h is not limited to the above, and for example, the relief surface 41h may be configured as a large-diameter cylindrical surface that is parallel to the cylindrical surface 41g and has a larger diameter than the cylindrical surface 41g (not shown). In this case, a step portion (e.g., a flat surface perpendicular to the axial direction) is formed between the cylindrical surface 41g and the relief surface 41h (large-diameter cylindrical surface) to connect them.

図６に示す第３実施形態では、中空シャフト４１の内周面に、円筒面４１ｇの軸方向内側に設けられた小径円筒面４１ｉと、円筒面４１ｇと小径円筒面４１ｉとの繋ぐ段差部４１ｊとが設けられる。小径円筒面４１ｉの内径Ｄｉｓは、円筒面４１ｇの内径Ｄｉよりも小さい。図示例では、段差部４１ｊが、軸方向と直交する平坦面で構成される。閉塞部材４２を段差部４１ｊに軸方向外側から当接させることにより、閉塞部材４２を中空シャフト４１に対して軸方向で位置決めすることができる。 In the third embodiment shown in FIG. 6, the inner circumferential surface of the hollow shaft 41 is provided with a small-diameter cylindrical surface 41i provided on the axially inner side of the cylindrical surface 41g, and a step portion 41j connecting the cylindrical surface 41g and the small-diameter cylindrical surface 41i. The inner diameter Dis of the small-diameter cylindrical surface 41i is smaller than the inner diameter Di of the cylindrical surface 41g. In the illustrated example, the step portion 41j is composed of a flat surface perpendicular to the axial direction. The blocking member 42 can be positioned in the axial direction relative to the hollow shaft 41 by abutting the step portion 41j from the axially outer side.

以上の実施形態では、閉塞部材４２の軸端側（軸方向外側）の端部が、円筒面４１ｇと逃げ面４１ｈとの境界に配された場合を示しているが、これに限らず、例えば、閉塞部材４２を、円筒面４１ｇと逃げ面４１ｈとの境界よりも反軸端側（軸方向内側）に押し込んでもよい。反対に、閉塞部材４２の軸端側の端部を、円筒面４１ｇと逃げ面４１ｈとの境界よりも軸端側に配してもよい。これにより、円筒面４１ｇの有効嵌合面（閉塞部材４２と嵌合する領域）の軸方向寸法を短くすることができるため、嵌合代の規定範囲を少なくすることが可能となり、例えば管理工数の簡素化を図ることができる。この場合、閉塞部材４２と円筒面４１ｇとの嵌合部の面積を最低限確保するために、閉塞部材４２の軸端側の端部を、逃げ面４１ｈの軸方向領域内に配することが好ましい。 In the above embodiment, the axial end side (axial outer side) end of the blocking member 42 is disposed at the boundary between the cylindrical surface 41g and the flank surface 41h, but this is not limited thereto. For example, the blocking member 42 may be pushed toward the opposite axial end side (axial inner side) from the boundary between the cylindrical surface 41g and the flank surface 41h. Conversely, the axial end side end of the blocking member 42 may be disposed on the axial end side from the boundary between the cylindrical surface 41g and the flank surface 41h. This allows the axial dimension of the effective fitting surface (area that fits with the blocking member 42) of the cylindrical surface 41g to be shortened, making it possible to reduce the prescribed range of the fitting allowance, and for example, simplifying the management labor. In this case, in order to ensure a minimum area of the fitting portion between the blocking member 42 and the cylindrical surface 41g, it is preferable to dispose the axial end side end of the blocking member 42 within the axial region of the flank surface 41h.

以上の実施形態では、本発明に係る動力伝達シャフトをドライブシャフトに適用した場合を示したが、これに限られない。例えば、プロペラシャフトや、等速自在継手のロングステム部に、本発明の動力伝達シャフトを適用することができる。 In the above embodiment, the power transmission shaft according to the present invention is applied to a drive shaft, but this is not limited to this. For example, the power transmission shaft according to the present invention can be applied to a propeller shaft or the long stem portion of a constant velocity universal joint.

図７に示す第４実施形態は、本発明の動力伝達シャフトを、等速自在継手の外側継手部材６０のロングステム部６２に適用した場合を示す。外側継手部材６０は、カップ状のマウス部６１と、マウス部６１に接合されたロングステム部６２とを有する。マウス部６１の内周には、内側継手部材と、外側継手部材６０及び内側継手部材と係合してトルクを伝達するトルク伝達部材とが収容される。このようなロングステム部６２を有する外側継手部材は、通常、ドライブシャフトのインボード側に設けられる摺動式等速自在継手に適用され、例えば、図１に示す摺動式等速自在継手３の外側継手部材３１の代わりに使用することができる。 The fourth embodiment shown in FIG. 7 shows the case where the power transmission shaft of the present invention is applied to the long stem portion 62 of the outer joint member 60 of a constant velocity universal joint. The outer joint member 60 has a cup-shaped mouth portion 61 and a long stem portion 62 joined to the mouth portion 61. The inner circumference of the mouth portion 61 houses an inner joint member and a torque transmission member that engages with the outer joint member 60 and the inner joint member to transmit torque. An outer joint member having such a long stem portion 62 is usually applied to a sliding type constant velocity universal joint provided on the inboard side of a drive shaft, and can be used, for example, in place of the outer joint member 31 of the sliding type constant velocity universal joint 3 shown in FIG. 1.

ロングステム部６２は、軸方向両端に開口した内孔６３ａを有する中空シャフトとしての中空ステム軸６３と、中空ステム軸６３の反マウス部側（図中右側）の開口部に装着された閉塞部材６４とを有する。中空ステム軸６３の外周面の反マウス部側の端部付近には、デファレンシャルギアに装着される雄スプライン６３ｂが形成される。マウス部６１には、底部から軸方向に延びる短軸部６１ａが一体に設けられる。この短軸部６１ａの反マウス部側の端部と中空ステム軸６３のマウス部６１側の端部とが、摩擦圧接等の適宜の方法で接合される。マウス部６１の短軸部６１ａの外周面に、図示しないサポートベアリングが装着される。このサポートベアリングを介して、外側継手部材６０が、回転自在な状態で車体に支持される。 The long stem portion 62 has a hollow stem shaft 63 as a hollow shaft having an inner hole 63a open at both axial ends, and a blocking member 64 attached to the opening on the anti-mouth side (right side in the figure) of the hollow stem shaft 63. A male spline 63b to be attached to a differential gear is formed near the end of the anti-mouth side of the outer peripheral surface of the hollow stem shaft 63. A short shaft portion 61a extending axially from the bottom is integrally provided on the mouth portion 61. The end of the short shaft portion 61a on the anti-mouth side and the end of the hollow stem shaft 63 on the mouth portion 61 side are joined by an appropriate method such as friction welding. A support bearing (not shown) is attached to the outer peripheral surface of the short shaft portion 61a of the mouth portion 61. The outer joint member 60 is supported on the vehicle body in a freely rotatable state via this support bearing.

図８に示すように、中空ステム軸６３の内周面の反マウス部側（図中右側）の端部には、面取り部６３ｃ、円筒面６３ｄ、及び逃げ面６３ｅが形成される。これらの面取り部６３ｃ、円筒面６３ｄ、及び逃げ面６３ｅは、図３に示す実施形態の面取り部４１ｆ、円筒面４１ｇ、及び逃げ面４１ｈと同様の構成を有する。閉塞部材６４は、図３の実施形態の閉塞部材４２と同様の構成を有し、閉塞部材６４の外周面が中空ステム軸６３の円筒面６３ｄに圧入される。尚、図８で散点を付した領域は、熱処理工程で硬化した領域を示す。 As shown in FIG. 8, a chamfered portion 63c, a cylindrical surface 63d, and a clearance surface 63e are formed on the end of the inner surface of the hollow stem shaft 63 on the side opposite the mouth portion (the right side in the figure). These chamfered portion 63c, cylindrical surface 63d, and clearance surface 63e have the same configuration as the chamfered portion 41f, cylindrical surface 41g, and clearance surface 41h in the embodiment shown in FIG. 3. The blocking member 64 has the same configuration as the blocking member 42 in the embodiment in FIG. 3, and the outer surface of the blocking member 64 is pressed into the cylindrical surface 63d of the hollow stem shaft 63. The dotted areas in FIG. 8 indicate areas hardened by the heat treatment process.

中空ステム軸６３は、上記の実施形態の中空シャフト４１と同様に、絞り工程、旋削工程、転造工程、熱処理工程を経て製造される。この実施形態でも、外周旋削工程や転造工程で中空ステム軸６３の端部の面取り部６３ｃ付近に発生する盛り上がり部が、円筒面６３ｄよりも外径側に後退した逃げ面６３ｅに形成されるため、この盛り上がり部が中空ステム軸６３の円筒面６３ｄへの閉塞部材６４の圧入に影響を及ぼす事態を防止できる。 The hollow stem shaft 63 is manufactured through a drawing process, a turning process, a rolling process, and a heat treatment process, similar to the hollow shaft 41 of the above embodiment. In this embodiment, too, the raised portion that occurs near the chamfered portion 63c at the end of the hollow stem shaft 63 during the outer peripheral turning process and the rolling process is formed on the relief surface 63e that is recessed toward the outer diameter side from the cylindrical surface 63d, so that it is possible to prevent the raised portion from affecting the press-fitting of the blocking member 64 into the cylindrical surface 63d of the hollow stem shaft 63.

また、閉塞部材４２は上記に限らず、例えば、軸方向中間部を膨出させた樽型の外周面を有する閉塞部材や、ゴム等の弾性に富んだ部材で形成した閉塞部材を用いてもよい。 The blocking member 42 is not limited to the above, and may be, for example, a blocking member having a barrel-shaped outer periphery with a bulging axial middle portion, or a blocking member made of a highly elastic material such as rubber.

１ドライブシャフト
２固定式等速自在継手
３摺動式等速自在継手
４中間シャフト（動力伝達シャフト）
４１中空シャフト
４１ａ内孔
４１ｄ雄スプライン
４１ｅ止め輪溝
４１ｆ面取り部
４１ｇ円筒面
４１ｈ逃げ面
４１ｉ小径円筒面
４１ｊ段差部
４２閉塞部材
５０センター治具
６０外側継手部材
６１マウス部
６２ロングステム部（動力伝達シャフト）
６３中空ステム軸（中空シャフト）
６３ａ内孔
６３ｂ雄スプライン
６３ｃ面取り部
６３ｄ円筒面
６３ｅ逃げ面
６４閉塞部材 1 Drive shaft 2 Fixed constant velocity universal joint 3 Sliding constant velocity universal joint 4 Intermediate shaft (power transmission shaft)
41 Hollow shaft 41a Inner hole 41d Male spline 41e Retaining ring groove 41f Chamfered portion 41g Cylindrical surface 41h Relief surface 41i Small diameter cylindrical surface 41j Step portion 42 Closure member 50 Center jig 60 Outer joint member 61 Mouth portion 62 Long stem portion (power transmission shaft)
63 Hollow stem shaft (hollow shaft)
63a: inner hole 63b: male spline 63c: chamfered portion 63d: cylindrical surface 63e: relief surface 64: blocking member

Claims

a hollow shaft having an inner hole that is open to at least one axial side; and a blocking member that blocks an opening on one axial side of the inner hole of the hollow shaft,
the hollow shaft is a power transmission shaft having a tapered chamfered portion provided at one axial end of the inner hole, and a cylindrical surface provided on the other axial side of the chamfered portion and into which the blocking member is press-fitted,
A power transmission shaft, comprising: a relief surface between the chamfered portion and the cylindrical surface, the relief surface being recessed radially outward from the cylindrical surface.

The power transmission shaft according to claim 1, wherein the relief surface is formed as a tapered surface that increases in diameter toward one side in the axial direction.

The power transmission shaft according to claim 2, wherein the inclination angle of the relief surface relative to the axial direction is smaller than the inclination angle of the chamfered portion relative to the axial direction.

The power transmission shaft according to claim 2, wherein the inclination angle of the relief surface with respect to the axial direction is 1° to 5°.

The power transmission shaft according to claim 1, wherein the relief surface is formed as a concave curved surface that expands in diameter toward one side in the axial direction.

The power transmission shaft according to claim 1, wherein the diameter Dit at the boundary between the chamfered portion and the flank surface and the inner diameter Di of the cylindrical surface satisfy Dit > Di + 0.1 mm.

a small-diameter cylindrical surface that is provided on the other axial side of the cylindrical surface on an inner peripheral surface of the hollow shaft and has a smaller diameter than the cylindrical surface; and a step portion that connects the cylindrical surface and the small-diameter cylindrical surface,
The power transmission shaft according to claim 1 , wherein the step portion is in axial contact with the blocking member.

A drive shaft comprising the power transmission shaft according to claim 1 and a pair of constant velocity universal joints attached to both ends of the power transmission shaft.

2. An outer joint member comprising: the power transmission shaft according to claim 1; and a cup-shaped mouth portion joined to the other axial end of the power transmission shaft.