JP2010031929A

JP2010031929A - Elastic shaft coupling and electric power steering device

Info

Publication number: JP2010031929A
Application number: JP2008193254A
Authority: JP
Inventors: Haruhiko Kiyota; 晴彦清田
Original assignee: NSK Ltd
Current assignee: NSK Ltd
Priority date: 2008-07-28
Filing date: 2008-07-28
Publication date: 2010-02-12
Anticipated expiration: 2028-07-28
Also published as: JP4952677B2

Abstract

<P>PROBLEM TO BE SOLVED: To realize a structure constituted in a small type by the small number of part items, capable of securing sufficient durability, and having a high degree of freedom of design. <P>SOLUTION: A spline shaft part 11a on the output shaft 9a side is loosely engaged with an opening near part of a spline hole 10a on the worm shaft 6 side so as to be displaceable in the rotational direction. A collar 23 for arranging a second male spline part on an outer peripheral surface is engaged by a spline with the innermost part of the spline hole 10a without looseness in the rotational direction. A torque transmitting shock absorbing member 22 made of an elastic material and elastically deformable in the torque transmission direction, is arranged between this collar 23 sand the spline shaft part 11a. This torque transmitting shock absorbing member 22 and a distal end part of the spline shaft part 11a are engaged so that torque can be transmitted, and this torque transmitting shock absorbing member 22 and the collar 23 are engaged so that the torque can be transmitted. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

本発明の対象となる弾性軸継手及び電動式パワーステアリング装置のうちの電動式パワーステアリング装置は、自動車の操舵装置として利用するもので、電動モータを補助動力源として利用する事により、運転者がステアリングホイールを操作する為に要する力の軽減を図るものである。又、弾性軸継手は、例えばこの様な電動式パワーステアリング装置を構成する電動モータの出力軸と、減速機のウォーム軸とのトルク伝達部に組み込み、操舵時に運転者に違和感を与える事を防止しつつ、上記出力軸から上記ウォーム軸に上記補助動力を伝達するものである。 Of the elastic shaft coupling and the electric power steering apparatus that are the subject of the present invention, the electric power steering apparatus is used as a steering apparatus for an automobile. By using an electric motor as an auxiliary power source, the driver can This is intended to reduce the force required to operate the steering wheel. In addition, the elastic shaft coupling is incorporated in the torque transmission part between the output shaft of the electric motor constituting such an electric power steering device and the worm shaft of the speed reducer, for example, to prevent the driver from feeling uncomfortable during steering. However, the auxiliary power is transmitted from the output shaft to the worm shaft.

操舵輪（フォークリフト等の特殊車両を除き、通常は前輪）に舵角を付与する際に運転者がステアリングホイールを操作する為に要する力の軽減を図る為の装置として、パワーステアリング装置が広く使用されている。又、この様なパワーステアリング装置で、補助動力源として電動モータを使用する電動式パワーステアリング装置も、広く実施されている。この様な電動式パワーステアリング装置の構造は、各種知られているが、何れの構造の場合でも、ステアリングホイールの操作によって回転させられ、回転に伴って操舵輪に舵角を付与する回転軸に電動モータの補助動力を、減速機を介して付与する。この減速機として一般的には、ウォーム減速機が使用されている。ウォーム減速機を使用した電動式パワーステアリング装置の場合、上記電動モータにより回転駆動されるウォームと、上記回転軸と共に回転するウォームホイールとを噛合させて、上記電動モータの補助動力をこの回転軸に伝達自在とする。 A power steering device is widely used as a device to reduce the force required for the driver to operate the steering wheel when giving a steering angle to the steered wheels (usually the front wheels except for special vehicles such as forklifts) Has been. Also, in such a power steering device, an electric power steering device using an electric motor as an auxiliary power source has been widely implemented. Various structures of such an electric power steering apparatus are known, but in any structure, a rotating shaft that is rotated by the operation of the steering wheel and gives a steered angle to the steered wheels as it rotates. Auxiliary power of the electric motor is applied through a speed reducer. In general, a worm reducer is used as the reducer. In the case of an electric power steering device using a worm speed reducer, a worm that is rotationally driven by the electric motor and a worm wheel that rotates together with the rotating shaft are engaged with each other, and auxiliary power of the electric motor is applied to the rotating shaft. Communicate freely.

この様なウォーム減速機を使用した電動式パワーステアリング装置として従来から、例えば特許文献１には、図１４〜１５に示す様な構造が記載されている。この従来構造の場合、ステアリングホイール１により所定方向に回転させられる、回転軸であるステアリングシャフト２の前端部は、ハウジング３の内側に回転自在に支持しており、この部分にウォームホイール４を固定している。このウォームホイール４と噛合するウォーム歯５をウォーム軸６の軸方向中間部に設けたウォーム７を、電動モータ８の出力軸９により、回転駆動自在としている。この為に、上記ウォーム軸６の基端面（図１５の左端面）中央部に開口したスプライン孔１０と、上記出力軸９の先端部に設けたスプライン軸部１１とをスプライン係合させている。 Conventionally, for example, Patent Document 1 describes a structure as shown in FIGS. 14 to 15 as an electric power steering apparatus using such a worm reduction gear. In the case of this conventional structure, the front end portion of the steering shaft 2 that is a rotating shaft that is rotated in a predetermined direction by the steering wheel 1 is rotatably supported inside the housing 3, and the worm wheel 4 is fixed to this portion. is doing. A worm 7 provided with worm teeth 5 meshing with the worm wheel 4 at an intermediate portion in the axial direction of the worm shaft 6 is rotatable by an output shaft 9 of an electric motor 8. For this purpose, the spline hole 10 opened at the center of the base end surface (left end surface in FIG. 15) of the worm shaft 6 and the spline shaft portion 11 provided at the distal end portion of the output shaft 9 are spline-engaged. .

図示の例では、上記ウォーム７の両端部は、深溝型玉軸受等の１対の転がり軸受１２ａ、１２ｂにより、上記ハウジング３内に回転自在に支持している。更に、上記ウォーム軸６の先端部で上記転がり軸受１２ａよりも突出した部分に押圧駒１３を外嵌し、この押圧駒１３と上記ハウジング３との間に、コイルばね１４等の弾性部材を設けている。そして、このコイルばね１４により、上記押圧駒１３を介して、上記ウォーム軸６に設けたウォーム歯５を、上記ウォームホイール４に向け押圧している。この様な構成により、これらウォーム歯５とウォームホイール４との間のバックラッシュを抑え、ウォーム式減速機１５部分での、歯打ち音の発生を抑えている。 In the illustrated example, both ends of the worm 7 are rotatably supported in the housing 3 by a pair of rolling bearings 12a and 12b such as deep groove ball bearings. Further, a pressing piece 13 is externally fitted to a portion protruding from the rolling bearing 12 a at the tip of the worm shaft 6, and an elastic member such as a coil spring 14 is provided between the pressing piece 13 and the housing 3. ing. The worm teeth 5 provided on the worm shaft 6 are pressed against the worm wheel 4 by the coil spring 14 via the pressing piece 13. With such a configuration, backlash between the worm teeth 5 and the worm wheel 4 is suppressed, and generation of rattling noise at the worm type reduction gear 15 is suppressed.

上述の様な従来構造の場合、上記ウォーム歯５と上記ウォームホイール４との噛合部で上記歯打ち音が発生する事を抑えられるが、上記電動モータ８の出力軸９の先端部に設けたスプライン軸部１１と、上記ウォーム軸６の基端部に設けたスプライン孔１０とのスプライン係合部で発生する歯打ち音を抑える事はできない。上記スプライン軸部１１と上記スプライン孔１０とが円周方向の隙間なく（バックラッシュ無しで）スプライン係合していれば、上記出力軸９の先端部と上記ウォーム軸６の基端部との結合部（スプライン係合部）で歯打ち音が発生する事はない。但し、実際の場合には、このスプライン係合部にはバックラッシュが存在する。又、単なるスプライン係合部の場合、上記電動モータ８への通電開始に伴って上記出力軸９から上記ウォーム軸６に、突然大きなトルクが伝達され始める。この為、前記ステアリングホイール１の操作開始直後に、突然このステアリングホイール１を操作する為に要する力が急減する。この様な状況は、運転者に違和感を与える為、好ましくない。 In the case of the conventional structure as described above, it is possible to suppress the occurrence of the rattling noise at the meshing portion between the worm tooth 5 and the worm wheel 4, but it is provided at the tip of the output shaft 9 of the electric motor 8. The rattling noise generated at the spline engaging portion between the spline shaft portion 11 and the spline hole 10 provided at the base end portion of the worm shaft 6 cannot be suppressed. If the spline shaft portion 11 and the spline hole 10 are spline-engaged without any circumferential clearance (without backlash), the distal end portion of the output shaft 9 and the proximal end portion of the worm shaft 6 No rattling noise is generated at the coupling part (spline engaging part). However, in the actual case, a backlash exists in the spline engaging portion. In the case of a simple spline engaging portion, a large torque suddenly starts to be transmitted from the output shaft 9 to the worm shaft 6 with the start of energization of the electric motor 8. For this reason, immediately after the operation of the steering wheel 1 is started, the force required to operate the steering wheel 1 suddenly decreases. Such a situation is not preferable because it gives the driver an uncomfortable feeling.

特に、前述の図１５に示した様に、上記ウォーム式減速機１５部分の噛合部に存在するバックラッシュを解消する為、上記コイルばね１４等の弾性部材により、上記ウォーム軸６に設けたウォーム歯５を上記ウォームホイール４に向け押圧する構造の場合には、このウォーム軸６の基端部を上記出力軸９の先端部に対し、揺動可能に結合する事が必須になる。この為、この結合部を単なるスプライン係合により構成する場合には、このスプライン係合部のバックラッシュを大きくせざるを得ず、上記問題が顕著になり易い。 In particular, as shown in FIG. 15, the worm shaft 6 is provided on the worm shaft 6 by an elastic member such as the coil spring 14 in order to eliminate the backlash existing in the meshing portion of the worm type reduction gear 15 portion. In the case of a structure in which the teeth 5 are pressed toward the worm wheel 4, it is essential that the base end portion of the worm shaft 6 is pivotably coupled to the distal end portion of the output shaft 9. For this reason, in the case where the coupling portion is formed by simple spline engagement, the backlash of the spline engagement portion must be increased, and the above problem is likely to become remarkable.

一方、特許文献２には、それぞれの断面形状を小判形とした、駆動軸の外周面と被駆動軸の内周面との間に筒状の弾性体を介在させた、弾性軸継手に関する発明が記載されている。但し、上記特許文献２に記載された発明の構造では、駆動軸から被駆動軸に伝達するトルクが小さい場合だけでなく、大きい場合にも、上記弾性体を介してこのトルクを伝達する為、この弾性体がへたりやすく、上記弾性軸継手全体としての耐久性確保が難しい。更に、特許文献３には、弾性が互いに異なる２種類の弾性材を利用する事で、バックラッシュの解消を図る弾性軸継手の構造が記載されている。但し、この様な特許文献３に記載された弾性軸継手の構造は、部品点数が多く、コストが嵩むだけでなく、外径が大きく、重量が嵩む等の不利益がある。 On the other hand, Patent Document 2 discloses an invention related to an elastic shaft coupling in which each cross-sectional shape is oval and a cylindrical elastic body is interposed between the outer peripheral surface of the drive shaft and the inner peripheral surface of the driven shaft. Is described. However, in the structure of the invention described in Patent Document 2, not only when the torque transmitted from the drive shaft to the driven shaft is small, but also when the torque is large, the torque is transmitted via the elastic body. This elastic body is easy to sag, and it is difficult to ensure the durability of the elastic shaft joint as a whole. Furthermore, Patent Document 3 describes a structure of an elastic shaft joint that eliminates backlash by using two types of elastic materials having different elasticity. However, the structure of the elastic shaft coupling described in Patent Document 3 has disadvantages such as a large number of parts and high cost, but also a large outer diameter and a heavy weight.

これに対して、特願２００７−９０６８０には、図１６に示す様な、出力軸９ａと一体の（金属製の）第一スプライン軸部１６と、この第一スプライン軸部１６よりも先端側で上記出力軸９ａに外嵌した、弾性材製の第二スプライン軸部１７とを備えた、弾性軸継手の構造が開示されている。この第二スプライン軸部１７の外形は、上記第一スプライン軸部１６の外形よりも、少しだけ大きい。この先発明に係る構造の場合には、上記第二スプライン軸部１７を、前記ウォーム軸６の基端部に形成したスプライン孔１０（図１５参照）に隙間なく、上記第一スプライン軸部１６をこのスプライン孔１０に、回転方向の変位を可能に緩く、それぞれスプライン係合させる。上記出力軸９ａと上記ウォーム軸６との間で伝達するトルクが小さい場合には、上記第二スプライン軸部１７が弾性変形しつつこのトルクを伝達する。これに対して、このトルクが大きくなると、上記第二スプライン軸部１７に加えて、上記第一スプライン軸部１６も、このトルク（第二スプライン軸部１７により伝達し切れないトルク）を伝達する。 On the other hand, in Japanese Patent Application No. 2007-90680, as shown in FIG. 16, the first spline shaft portion 16 (made of metal) integrated with the output shaft 9 a and the tip side of the first spline shaft portion 16 are provided. The structure of the elastic shaft coupling including the second spline shaft portion 17 made of an elastic material and externally fitted to the output shaft 9a is disclosed. The outer shape of the second spline shaft portion 17 is slightly larger than the outer shape of the first spline shaft portion 16. In the case of the structure according to the previous invention, the first spline shaft portion 16 is connected to the spline hole 10 (see FIG. 15) formed in the base end portion of the worm shaft 6 without any gap. The spline holes 10 are loosely displaceable in the rotational direction and engaged with the splines, respectively. When the torque transmitted between the output shaft 9a and the worm shaft 6 is small, the second spline shaft portion 17 transmits this torque while being elastically deformed. On the other hand, when this torque increases, in addition to the second spline shaft portion 17, the first spline shaft portion 16 also transmits this torque (torque that cannot be transmitted by the second spline shaft portion 17). .

この様な先発明に係る弾性軸継手は、少ない部品点数で小型に構成でき、しかも十分な耐久性を確保できるが、設計の自由度が限られる。即ち、上記出力軸９ａの中間部先端寄り部分に上記第一スプライン軸部１６を、この第一スプライン軸部１６よりも先端側に突出した部分に、上記第二スプライン軸部１７の全長に見合う非円形柱部１８を、それぞれ形成する必要上、上記出力軸９ａのうちで電動モータ８（図１４〜１５参照）のケースから突出した部分の軸方向長さを、或る程度以上確保する必要がある。 Such an elastic shaft coupling according to the prior invention can be made compact with a small number of parts, and sufficient durability can be ensured, but the degree of design freedom is limited. That is, the first spline shaft portion 16 is located near the tip of the intermediate portion of the output shaft 9a, and the length of the second spline shaft portion 17 is commensurate with the portion protruding toward the tip of the first spline shaft portion 16. In order to form the non-circular column portions 18 respectively, it is necessary to secure a certain axial length or more of the portion of the output shaft 9a protruding from the case of the electric motor 8 (see FIGS. 14 to 15). There is.

特開２００４−３０６８９８号公報JP 2004-306898 A 特開２００２−２１１４１８号公報JP 2002-211141 A 特開２００６−１８３６７６号公報JP 2006-183676 A

本発明は、上述の様な事情に鑑み、前述の特許文献３に記載された従来構造に比べ、小型に構成できて、しかも十分な耐久性を確保でき、且つ、設計の自由度が高い、弾性軸継手、及びこの弾性軸継手を組み込んだ電動式パワーステアリング装置を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 be configured smaller than the conventional structure described in Patent Document 3 described above, and can ensure sufficient durability, and has a high degree of design freedom. The present invention has been invented to realize an elastic shaft joint and an electric power steering apparatus incorporating the elastic shaft joint.

本発明の弾性軸継手及び電動式パワーステアリング装置のうち、請求項１に記載した弾性軸継手の発明は、軸方向に関して互いに直列に配置された１対の回転軸の端部同士の間でトルクを伝達する為のもので、スプライン孔とスプライン軸部とを備える。
このうちのスプライン孔は、上記両回転軸のうちの一方の回転軸の端面に開口する状態で設けられたもので、内周面に雌スプライン部を形成している。
又、上記スプライン軸部は、上記両回転軸のうちの他方の回転軸の端部に設けられたもので、外周面に雄スプライン部を形成している。
そして、上記スプライン孔と上記スプライン軸部とをスプライン係合させる事により、上記両回転軸同士の間でトルクの伝達を可能としている。 Among the elastic shaft coupling and the electric power steering apparatus according to the present invention, the elastic shaft coupling invention described in claim 1 is a torque between ends of a pair of rotating shafts arranged in series in the axial direction. It is provided with a spline hole and a spline shaft portion.
Of these, the spline hole is provided so as to open to the end surface of one of the two rotating shafts, and forms a female spline portion on the inner peripheral surface.
The spline shaft portion is provided at the end of the other rotation shaft of the two rotation shafts, and forms a male spline portion on the outer peripheral surface.
And by transmitting the said spline hole and the said spline shaft part by spline, it is possible to transmit torque between the both rotating shafts.

特に、本発明の弾性軸継手に於いては、上記スプライン軸部は上記スプライン孔の開口寄り部分に、回転方向の変位を可能に、緩く係合している。
又、外周面に第二雄スプライン部を設けたカラーが上記スプライン孔の奥部に、回転方向のがたつきなくスプライン係合している。
更に、このカラーと上記スプライン軸部との間に、弾性材製でトルクの伝達方向に弾性変形可能なトルク伝達用緩衝部材を設けている。
そして、このトルク伝達用緩衝部材と上記スプライン軸部の先端部分とをトルク伝達可能に係合させると共に、このトルク伝達用緩衝部材と上記カラーとをトルク伝達可能に係合させている。 In particular, in the elastic shaft coupling of the present invention, the spline shaft portion is loosely engaged with a portion close to the opening of the spline hole so as to allow displacement in the rotational direction.
Further, a collar provided with a second male spline portion on the outer peripheral surface is engaged with the back portion of the spline hole without spattering in the rotational direction.
Furthermore, a torque transmission buffer member made of an elastic material and elastically deformable in the torque transmission direction is provided between the collar and the spline shaft portion.
The torque transmission buffer member and the tip portion of the spline shaft portion are engaged so as to transmit torque, and the torque transmission buffer member and the collar are engaged so as to transmit torque.

上述の様な本発明の弾性軸継手を実施する場合に、例えば請求項２に記載した発明の様に、上記トルク伝達用緩衝部材を、上記スプライン孔の軸方向中間部で、上記スプライン軸部の先端面と上記カラーの基端面との間に配置する。そして、このスプライン軸部の先端部と上記トルク伝達用緩衝部材の基端部とを、このトルク伝達用緩衝部材の先端部とカラーの基端部とを、それぞれトルクの伝達を可能に凹凸係合させる。
或いは、請求項３に記載した発明の様に、上記トルク伝達用緩衝部材の外周面と上記カラーの内周面とを、トルク伝達可能に凹凸係合させる。又、このトルク伝達用緩衝部材の内周面と上記スプライン軸部の先端面に形成した係合凸部とを、トルク伝達可能に凹凸係合させる。 When the elastic shaft coupling of the present invention as described above is implemented, for example, as in the invention described in claim 2, the torque transmission buffer member is arranged at the intermediate portion in the axial direction of the spline hole, and the spline shaft portion. It arrange | positions between the front end surface of this, and the base end surface of the said color | collar. Then, the tip end portion of the spline shaft portion and the base end portion of the torque transmission buffer member are connected to the concave portion of the torque transmission buffer member and the base end portion of the collar so that torque can be transmitted. Combine.
Alternatively, as in the third aspect of the invention, the outer peripheral surface of the torque transmitting buffer member and the inner peripheral surface of the collar are engaged with each other so as to transmit torque. Further, the inner peripheral surface of the torque transmitting buffer member and the engaging convex portion formed on the tip end surface of the spline shaft portion are engaged with each other so as to transmit torque.

又、請求項４に記載した、電動式パワーステアリング装置は、前述した従来から知られている電動式パワーステアリング装置と同様に、ハウジングと、回転軸と、ウォームホイールと、ウォームと、電動モータと、継手装置とを備える。
このうちのハウジングは、固定の部分に支持されて回転する事がない。尚、このハウジングは、前述の図１４に示す様な、コラムタイプの電動式パワーステアリング装置の場合には、ステアリングコラム１９の端部に固定したハウジング３が相当する。これに対して、電動モータをステアリングギヤユニット２０（図１４参照）部分に組み付ける構造の場合には、このステアリングギヤユニット２０のケースが相当する。
又、上記回転軸は、このハウジングに対し回転自在に設けられて、ステアリングホイールの操作により回転させられ、回転に伴って操舵輪に舵角を付与する。尚、この回転軸は、上記図１４に示す様な、コラムタイプの電動式パワーステアリング装置の場合には、ステアリングシャフト２が相当する。これに対して、電動モータをステアリングギヤユニット２０（図１４参照）部分に組み付ける構造の場合には、ピニオン軸が相当する。
又、上記ウォームホイールは、上記ハウジングの内部で上記回転軸の一部に、この回転軸と同心に支持されて、この回転軸と共に回転する。
又、上記ウォームは、ウォーム軸の軸方向中間部にウォーム歯を設けて成り、このウォーム歯を上記ウォームホイールと噛合させた状態で、上記ウォーム軸の軸方向両端部をそれぞれ軸受により上記ハウジングに対し回転自在に支持している。
又、上記電動モータは、上記ウォームを回転駆動する為のものである。
更に、上記継手装置は、上記電動モータの出力軸の先端部と上記ウォーム軸の基端部との間に設けられたもので、これら両軸同士の間でトルクを伝達する。
特に、本発明の電動式パワーステアリング装置に於いては、上記継手装置が、上述した構成を有する、本発明の弾性軸継手である。 Further, the electric power steering device according to claim 4 is similar to the above-described conventionally known electric power steering device, and includes a housing, a rotating shaft, a worm wheel, a worm, an electric motor, And a joint device.
Of these, the housing is supported by a fixed portion and does not rotate. Note that this housing corresponds to the housing 3 fixed to the end of the steering column 19 in the case of the column type electric power steering apparatus as shown in FIG. On the other hand, in the case of a structure in which the electric motor is assembled to the steering gear unit 20 (see FIG. 14), the case of the steering gear unit 20 corresponds.
The rotating shaft is provided so as to be rotatable with respect to the housing, and is rotated by an operation of a steering wheel, and gives a steering angle to the steered wheels as it rotates. Note that this rotating shaft corresponds to the steering shaft 2 in the case of a column-type electric power steering apparatus as shown in FIG. On the other hand, in the case of a structure in which the electric motor is assembled to the steering gear unit 20 (see FIG. 14), a pinion shaft corresponds.
The worm wheel is supported on a part of the rotating shaft inside the housing, concentrically with the rotating shaft, and rotates together with the rotating shaft.
The worm is formed by providing worm teeth at the axial intermediate portion of the worm shaft, and in the state where the worm teeth are engaged with the worm wheel, both end portions in the axial direction of the worm shaft are respectively attached to the housing by bearings. It is supported so that it can rotate freely.
The electric motor is for rotating the worm.
Further, the joint device is provided between the distal end portion of the output shaft of the electric motor and the proximal end portion of the worm shaft, and transmits torque between these two shafts.
In particular, in the electric power steering apparatus of the present invention, the joint device is the elastic shaft joint of the present invention having the above-described configuration.

上述の様な構成を有する本発明の弾性軸継手の場合、１対の回転軸同士の間でトルクを伝達し始める際、及び、これら両回転軸同士の間で伝達するトルクが小さい場合には、トルク伝達用緩衝部材がこのトルクを伝達する。この際、このトルク伝達用緩衝部材が、このトルクの伝達方向に弾性変形しつつ、このトルクを伝達する。この状態では、一方の回転軸のスプライン孔を構成する雌スプライン歯の円周方向側面と、他方の回転軸に設けたスプライン軸部を構成する雄スプライン歯の円周方向側面との間には、隙間が存在する。従って、上記トルクの伝達開始直後から、急に大きなトルクが伝達される事がなく（過渡特性を良好にして）、電動式パワーステアリング装置に組み込んだ場合に、ステアリングホイールを操作する運転者に違和感を与えない様にできる。又、それぞれが金属等の硬質材製である、上記１対の回転軸同士が衝突する事で、耳障りな異音が発生する事も防止できる。 In the case of the elastic shaft coupling of the present invention having the above-described configuration, when torque is transmitted between a pair of rotating shafts and when the torque transmitted between these rotating shafts is small The torque transmission buffer member transmits this torque. At this time, the torque transmission buffer member transmits this torque while elastically deforming in the torque transmission direction. In this state, between the circumferential side surface of the female spline teeth constituting the spline hole of one rotating shaft and the circumferential side surface of the male spline teeth constituting the spline shaft portion provided on the other rotating shaft. , There is a gap. Therefore, immediately after starting the transmission of the torque, a large torque is not suddenly transmitted (with excellent transient characteristics), and when incorporated in an electric power steering device, the driver who operates the steering wheel feels uncomfortable. Can not be given. In addition, it is possible to prevent annoying noises from occurring due to collision between the pair of rotating shafts, each made of a hard material such as metal.

これに対して、上記両回転軸同士の間で伝達するトルクが大きくなり、上記トルク伝達用緩衝部材の弾性変形量が多くなると、上記雌、雄各スプライン歯の円周方向側面同士が当接する。そして、上記トルク伝達用緩衝部材が伝達し切れないトルクを、上記両回転軸同士の間で（スプライン係合により）直接伝達する。このトルクが上昇する過程で、上記トルク伝達用緩衝部材の作用により、上記両回転軸同士の回転方向に関する相対変位速度が低下する。従って、上記雌、雄各スプライン歯の円周方向側面同士が当接する際には、上記相対変位速度は限られた大きさになり、これら各スプライン歯の円周方向側面同士の衝突により耳障りな異音が発生する事はない。更に、上記トルクが大きい場合にも、上記トルク伝達用緩衝部材が伝達するトルクは限られた値となり、このトルク伝達用緩衝部材の弾性変形量も限られる為、このトルク伝達用緩衝部材の耐久性を十分に確保できる。 On the other hand, when the torque transmitted between the rotating shafts increases and the amount of elastic deformation of the torque transmitting buffer member increases, the circumferential side surfaces of the female and male spline teeth come into contact with each other. . The torque that cannot be transmitted by the torque transmitting buffer member is directly transmitted between the rotating shafts (by spline engagement). In the process of increasing the torque, the relative displacement speed in the rotational direction between the two rotating shafts decreases due to the action of the torque transmitting buffer member. Accordingly, when the circumferential side surfaces of the female and male spline teeth come into contact with each other, the relative displacement speed becomes a limited magnitude, and it is uncomfortable due to the collision between the circumferential side surfaces of the spline teeth. No abnormal noise is generated. Further, even when the torque is large, the torque transmitted by the torque transmission buffer member is limited, and the amount of elastic deformation of the torque transmission buffer member is also limited. Enough to secure.

前述の様に構成し、上述の様に作用する本発明の弾性軸継手によれば、前述の特許文献３に記載された従来構造に比べ、小型に構成できて、しかも十分な耐久性を確保でき、且つ、設計の自由度が高い弾性軸継手及び電動式パワーステアリング装置を実現できる。
即ち、本発明の弾性軸継手は、１対の回転軸同士を、カラーとトルク伝達用緩衝部材とを介して組み合わせている為、前述の特許文献３に記載された従来構造に比べ、少ない部品点数で構成できる。
又、上記カラー及びトルク伝達用緩衝部材は、一方の回転軸に設けたスプライン孔の内部に組み込む為、上記特許文献３に記載された従来構造の様に直径が大きくなる事はなく、小型に構成できる。
又、大きなトルクを伝達する場合でも、上記トルク伝達用緩衝部材の弾性変形量が過大になる事はないので、このトルク伝達用緩衝部材を組み込んだ弾性軸継手の耐久性を十分に確保できる。
更に、スプライン孔を備えた一方の回転軸と、スプライン軸部を備えた他方の回転軸とを、カラーと上記トルク伝達用緩衝部材とを介して組み合わせている為、この組み合わせ部の構造を設計する場合の自由度が高くなる。又、上記両回転軸の形状を単純化し易く、生産性の向上も図れる。 According to the elastic shaft coupling of the present invention configured as described above and acting as described above, it can be configured smaller than the conventional structure described in Patent Document 3 described above, and sufficient durability is ensured. An elastic shaft coupling and an electric power steering device that can be designed and have a high degree of freedom in design can be realized.
That is, since the elastic shaft coupling of the present invention combines a pair of rotating shafts via a collar and a torque transmission buffer member, it has fewer parts than the conventional structure described in Patent Document 3 above. Can be composed of points.
Further, since the collar and the torque transmitting buffer member are incorporated in the inside of the spline hole provided on one rotating shaft, the diameter does not increase as in the conventional structure described in Patent Document 3, and the size is reduced. Can be configured.
In addition, even when a large torque is transmitted, the amount of elastic deformation of the torque transmitting buffer member does not become excessive, so that the durability of the elastic shaft coupling incorporating the torque transmitting buffer member can be sufficiently secured.
In addition, one rotating shaft with a spline hole and the other rotating shaft with a spline shaft part are combined via a collar and the torque transmission buffer member, so the structure of this combined part is designed. The degree of freedom when doing so increases. In addition, the shape of both rotary shafts can be easily simplified, and productivity can be improved.

［実施の形態の第１例］
図１〜７は、請求項１、２、４に対応する、本発明の実施の形態の第１例を示している。尚、本例の電動式パワーステアリング装置の特徴は、電動モータ８の出力軸９ａの先端部と、ウォーム軸６の基端部との結合部に設けた、弾性軸継手２１の構造にある。その他、電動式パワーステアリング装置全体の構造及び作用に就いては、広く実施されている従来構造と同様であるから、この従来構造と同等部分に関する図示並びに説明は、省略若しくは簡略にし、以下、本例の特徴部分を中心に説明する。尚、前述の図１４〜１５と図１とで、ハウジング３に対する電動モータ８の取付方向が異なっているが、この点は、設置する自動車に応じ適宜設計的に変更するものであって、本発明の特徴部分とは関係がない。 [First example of embodiment]
1 to 7 show a first example of an embodiment of the present invention corresponding to claims 1, 2, and 4. FIG. A feature of the electric power steering apparatus of this example is the structure of the elastic shaft coupling 21 provided at the coupling portion between the distal end portion of the output shaft 9 a of the electric motor 8 and the proximal end portion of the worm shaft 6. In addition, since the structure and operation of the entire electric power steering apparatus are the same as those of a widely implemented conventional structure, illustrations and explanations relating to parts equivalent to the conventional structure are omitted or simplified. The description will focus on the features of the example. 14 to 15 and FIG. 1 are different in the mounting direction of the electric motor 8 with respect to the housing 3, but this point is appropriately changed in design according to the automobile to be installed. It has nothing to do with the features of the invention.

本例の構造の場合には、図１〜２に示す様に、一方の回転軸である上記ウォーム軸６の基端部に、内周面に雌スプライン部を形成したスプライン孔１０ａを、このウォーム軸６の基端面に開口する状態で、このウォーム軸６と同心に形成している。又、図１、２、５、７に示す様に、上記出力軸９ａの先端部に、外周面に雄スプライン部を形成したスプライン軸部１１ａを、この出力軸９ａと同心に形成している。そして、このスプライン軸部１１ａと上記スプライン孔１０ａとをスプライン係合させる事で、上記出力軸９ａと上記ウォーム軸６とを、回転力の伝達を可能に結合している。 In the case of the structure of this example, as shown in FIGS. 1 and 2, a spline hole 10a having a female spline portion formed on the inner peripheral surface is formed at the base end portion of the worm shaft 6 which is one of the rotating shafts. The worm shaft 6 is formed concentrically with the worm shaft 6 in a state of opening to the base end surface. As shown in FIGS. 1, 2, 5, and 7, a spline shaft portion 11a having a male spline portion formed on the outer peripheral surface is formed concentrically with the output shaft 9a at the tip end portion of the output shaft 9a. . The spline shaft portion 11a and the spline hole 10a are spline-engaged so that the output shaft 9a and the worm shaft 6 are coupled so as to transmit a rotational force.

但し、上記スプライン軸部１１ａは上記スプライン孔１０ａの開口寄り（図１、２、７の右寄り）部分に、図５に示す様に、回転方向の変位を可能に、緩く係合している。上記スプライン軸部１１ａを構成する雄スプライン歯の円周方向側面と、上記スプライン孔１０ａを構成する雌スプライン歯の円周方向側面とは、上記両軸６、９ａ同士の間で伝達するトルクが大きい場合にのみ当接する。逆に言えば、上記雄、雌両スプライン歯の円周方向側面同士は、上記両軸６、９ａ同士の間で伝達するトルクが小さい場合には、上記図５に示す様に、互いに離隔したままとなる。これに対して、このトルクが大きくなると、上記雄スプライン歯の何れかの円周方向側面と、上記雌スプライン歯の何れかの円周方向側面とが、互いに当接する。又、上記スプライン軸部１１ａの先端面と上記スプライン孔１０ａの奥面とは、軸方向に互いに離隔している。そして、これらスプライン軸部１１ａの先端面とスプライン孔１０ａの奥面との間に、上記両軸６、９ａ同士の間で伝達するトルクが小さい場合にこのトルクを伝達する為の、トルク伝達用緩衝部材２２とカラー２３とを組み付けている。 However, as shown in FIG. 5, the spline shaft portion 11a is loosely engaged with the portion close to the opening of the spline hole 10a (rightward in FIGS. 1, 2 and 7) so as to be displaceable in the rotational direction. The torque transmitted between the shafts 6 and 9a between the circumferential side surfaces of the male spline teeth constituting the spline shaft portion 11a and the circumferential side surfaces of the female spline teeth constituting the spline hole 10a. Abuts only when large. In other words, the circumferential side surfaces of the male and female spline teeth are separated from each other as shown in FIG. 5 when the torque transmitted between the shafts 6 and 9a is small. Will remain. On the other hand, when the torque increases, any of the circumferential side surfaces of the male spline teeth comes into contact with any of the circumferential side surfaces of the female spline teeth. The tip surface of the spline shaft portion 11a and the back surface of the spline hole 10a are separated from each other in the axial direction. Then, when the torque transmitted between the shafts 6 and 9a is small between the tip surface of the spline shaft portion 11a and the back surface of the spline hole 10a, the torque is transmitted to transmit this torque. The buffer member 22 and the collar 23 are assembled.

このうちのカラー２３は、高機能樹脂等の硬質の合成樹脂、或いは、アルミニウム系合金、銅系合金の如き金属材料等、上記ウォーム軸６を構成する鉄系合金よりも軟質ではあるが、上記小さなトルクを伝達する面からは十分な剛性及び強度を確保できる材料により、一体に形成している。この様な上記カラー２３は、外周面に第二雄スプライン部を設けたもので、この第二雄スプライン部を上記スプライン孔１０ａの雌スプライン部に締り嵌めでスプライン係合させつつ、このスプライン孔１０ａに圧入する事により、このスプライン孔１０ａの奥部に、図３に示す様に、回転方向のがたつきなく固定している。又、上記カラー２３の軸方向両端面のうち、上記スプライン孔１０ａの開口側の端面に、十字形の被駆動側凸部２４を、上記カラー２３と同心に、突出形成している。 Of these, the collar 23 is softer than the iron-based alloy constituting the worm shaft 6 such as a hard synthetic resin such as a high-functional resin, or a metal material such as an aluminum-based alloy or a copper-based alloy. From a surface that transmits a small torque, it is integrally formed of a material that can secure sufficient rigidity and strength. The collar 23 is provided with a second male spline portion on the outer peripheral surface, and the second male spline portion is engaged with the female spline portion of the spline hole 10a by a spline engagement. By press-fitting into 10a, as shown in FIG. 3, it is fixed to the inner part of the spline hole 10a without rattling in the rotational direction. In addition, a cross-shaped driven-side convex portion 24 is formed concentrically with the collar 23 on the end face on the opening side of the spline hole 10 a among the axial end faces of the collar 23.

一方、上記トルク伝達用緩衝部材２２は、上記被駆動側凸部２４と、上記スプライン軸部１１ａの先端面に突設した駆動側凸部２５との間に、これら被駆動側凸部２４と駆動側凸部２５との間でのトルクの伝達を可能に掛け渡している。この駆動側凸部２５は、上記スプライン軸１１ａと同心の円柱部の円周方向の一部に平坦面を形成した如きもので、端面形状が略Ｄ字形である。又、本例の場合、上記トルク伝達用緩衝部材２２は、鉄系合金等の硬質金属製のブッシュ２６と、ニトリルゴム、シリコンゴム、ウレタンゴム等のゴム、ポリウレタン、ビニルの如きエラストマー、合成樹脂等、弾性を有する高分子材料製の弾性部材２７とを組み合わせ結合して成る。 On the other hand, the torque transmitting buffer member 22 includes the driven-side convex portion 24 and the driven-side convex portion 24 between the driven-side convex portion 24 and the driving-side convex portion 25 protruding from the tip surface of the spline shaft portion 11a. Torque is transmitted to and from the drive-side convex portion 25 so as to be possible. The drive-side convex portion 25 is such that a flat surface is formed on a portion of the cylindrical portion concentric with the spline shaft 11a in the circumferential direction, and the end surface shape is substantially D-shaped. In the case of this example, the torque transmission buffer member 22 includes a hard metal bush 26 such as an iron-based alloy, rubber such as nitrile rubber, silicon rubber and urethane rubber, elastomer such as polyurethane and vinyl, and synthetic resin. The elastic member 27 made of a polymer material having elasticity is combined and coupled.

このうちのブッシュ２６の軸方向寸法は、この弾性部材２７の軸方向寸法よりも短く（１／２程度で）、上記トルク伝達用緩衝部材２２のうちの前記出力軸９ａ側の半部で、上記弾性部材２７の内径側に包埋固定されている。この弾性部材２７と上記ブッシュ２６との結合強度を確保する為に、このブッシュ２６の外周面には、ローレット加工等により細かい凹凸を形成している。この様なブッシュ２６は、外周面にプライマを塗布した状態で金型のキャビティ内にセットし、このキャビティ内に上記高分子材料を送り込む事で、上記弾性部材２７を射出成形する。又、上記ブッシュ２６の中心部には、図６に示す様に、上記駆動側凸部２５を圧入可能な、端面形状が略Ｄ字形である、入力側係合孔２８を設けている。更に、上記弾性部材２７のうちで上記ブッシュ２６から外れた部分に、図４に示す様に、上記被駆動側凸部２４と係合自在な出力側係合孔２９を形成している。この様なトルク伝達用緩衝部材２２は、上記駆動側凸部２５と上記ブッシュ２６の入力側係合孔２８とを、上記出力側係合孔２９と上記被駆動側凸部２４とを、それぞれ嵌合させる事により、上記出力軸９ａの先端部分と上記カラー２３との間に、トルク伝達可能に組み付ける。 The axial dimension of the bush 26 is shorter than the axial dimension of the elastic member 27 (about ½), and is a half of the torque transmission buffer member 22 on the output shaft 9a side. It is embedded and fixed on the inner diameter side of the elastic member 27. In order to ensure the bonding strength between the elastic member 27 and the bush 26, fine irregularities are formed on the outer peripheral surface of the bush 26 by knurling or the like. Such a bush 26 is set in a cavity of a mold with a primer applied to the outer peripheral surface, and the elastic member 27 is injection-molded by feeding the polymer material into the cavity. Further, as shown in FIG. 6, an input side engagement hole 28 having an end surface shape that is substantially D-shaped and capable of press-fitting the drive side convex portion 25 is provided in the central portion of the bush 26. Further, as shown in FIG. 4, an output side engagement hole 29 that can be engaged with the driven side convex portion 24 is formed in a portion of the elastic member 27 that is disengaged from the bush 26. Such a torque transmission buffer member 22 includes the drive-side convex portion 25 and the input-side engagement hole 28 of the bush 26, and the output-side engagement hole 29 and the driven-side convex portion 24. By fitting, it is assembled between the tip portion of the output shaft 9a and the collar 23 so that torque can be transmitted.

上述の様な構成を有する本例の構造の場合、前記電動モータ８への通電開始直後、上記出力軸９ａから前記ウォーム軸６にトルクを伝達し始める際、及び、この出力軸９ａからこのウォーム軸６に伝達するトルクが小さい場合には、上記トルク伝達用緩衝部材２２がこのトルクを伝達する。即ち、上記出力軸９ａの回転が、上記駆動側凸部２５と上記入力側係合孔２８との係合に基づいて上記ブッシュ２６に伝わり、更に、上記弾性部材２７に伝わる。そして、この弾性変形２７が捩り方向に弾性変形しつつ、上記出力側係合孔２９と上記被駆動側凸部２４との係合に基づき、上記カラー２３にトルクを伝達する。この結果、このカラー２３を内嵌固定した上記ウォーム軸６に、上記トルクが伝達される。 In the case of the structure of this example having the above-described configuration, immediately after the start of energization of the electric motor 8, when the torque starts to be transmitted from the output shaft 9a to the worm shaft 6, and from the output shaft 9a to the worm When the torque transmitted to the shaft 6 is small, the torque transmitting buffer member 22 transmits this torque. That is, the rotation of the output shaft 9 a is transmitted to the bush 26 based on the engagement between the drive-side convex portion 25 and the input-side engagement hole 28, and further transmitted to the elastic member 27. Then, while the elastic deformation 27 is elastically deformed in the torsional direction, torque is transmitted to the collar 23 based on the engagement between the output side engagement hole 29 and the driven side convex portion 24. As a result, the torque is transmitted to the worm shaft 6 in which the collar 23 is fitted and fixed.

この際、このウォーム軸６側に設けたスプライン孔１０ａを構成する雌スプライン歯の円周方向側面と、上記出力軸９ａ側のスプライン軸部１１ａを構成する雄スプライン歯の円周方向側面との間には、隙間が存在したままとなる。従って、上記トルクの伝達開始直後から、急に大きなトルクが伝達される事がなく（過渡特性を良好にして）、電動式パワーステアリング装置に組み込んだ場合に、ステアリングホイール１（図１４参照）を操作する運転者に違和感を与えない様にできる。又、それぞれが鉄系合金等の硬質材製である、上記両軸６、９ａに設けた上記雄、雌各スプライン歯の円周方向側面同士が衝突する事で、耳障りな異音が発生する事も防止できる。 At this time, a circumferential side surface of the female spline teeth constituting the spline hole 10a provided on the worm shaft 6 side and a circumferential side surface of the male spline teeth constituting the spline shaft portion 11a on the output shaft 9a side are formed. A gap remains between them. Therefore, immediately after the transmission of the torque is started, a large torque is not transmitted suddenly (with excellent transient characteristics), and the steering wheel 1 (see FIG. 14) is incorporated into the electric power steering device. The driver who operates can be made not to feel strange. In addition, irritating abnormal noise is generated by the fact that the circumferential side surfaces of the male and female spline teeth provided on the shafts 6 and 9a are made of a hard material such as an iron-based alloy. Things can also be prevented.

これに対して、上記出力軸９ａから上記ウォーム軸６に伝達するトルクが大きくなり、上記トルク伝達用緩衝部材２２を構成する上記弾性部材２７の捩り方向の弾性変形量が多くなると、上記雄、雌各スプライン歯の円周方向側面同士が当接する。そして、上記トルク伝達用緩衝部材２２が伝達し切れないトルクを、上記出力軸９ａと上記ウォーム軸６との間で、上記スプライン軸部１１ａと上記スプライン孔１０ａとのスプライン係合に基づき、直接伝達する。上記出力軸９ａから上記ウォーム軸６に伝達するトルクが上昇する過程で、上記トルク伝達用緩衝部材２２の作用により、上記両軸９ａ、６同士の回転方向に関する相対変位速度が低下する。従って、上記雄、雌各スプライン歯の円周方向側面同士が当接する際には、上記相対変位速度は限られた大きさになり、これら各スプライン歯の円周方向側面同士の衝突により耳障りな異音が発生する事はない。更に、上記トルクが大きい場合にも、上記トルク伝達用緩衝部材２２を構成する上記弾性部材２７が伝達するトルクは限られた値となり、この弾性部材２７の弾性変形量も限られる為、この弾性部材２７を含む、上記トルク伝達用緩衝部材２２の耐久性を十分に確保できる。 On the other hand, when the torque transmitted from the output shaft 9a to the worm shaft 6 increases and the elastic deformation amount of the elastic member 27 constituting the torque transmitting buffer member 22 increases, the male, The circumferential side surfaces of the female spline teeth come into contact with each other. A torque that cannot be transmitted by the torque transmitting buffer member 22 is directly applied between the output shaft 9a and the worm shaft 6 based on the spline engagement between the spline shaft portion 11a and the spline hole 10a. introduce. In the process of increasing the torque transmitted from the output shaft 9a to the worm shaft 6, the relative displacement speed in the rotational direction between the shafts 9a and 6 decreases due to the action of the torque transmitting buffer member 22. Therefore, when the circumferential side surfaces of the male and female spline teeth come into contact with each other, the relative displacement speed becomes a limited magnitude, which is uncomfortable due to the collision between the circumferential side surfaces of the spline teeth. No abnormal noise is generated. Further, even when the torque is large, the torque transmitted by the elastic member 27 constituting the torque transmitting buffer member 22 has a limited value, and the elastic deformation amount of the elastic member 27 is also limited. The durability of the torque transmission buffer member 22 including the member 27 can be sufficiently secured.

［実施の形態の第２例］
図８は、請求項１、２、４に対応する、本発明の実施の形態の第２例を示している。本例の場合には、トルク伝達用緩衝部材２２ａを、端面形状が十字形である、弾性部材２７ａのみで構成している。又、出力軸９ｂの先端面に、端面形状が十字形の駆動側凹部（図示省略）を、カラー２３ａの基端面に端面形状が十字形の被駆動側凹部３０を、それぞれ形成している。そして、弾性軸継手２１ａの組立状態では、上記トルク伝達用緩衝部材２２ａの軸方向両端部を、上記駆動側凹部と上記被駆動側凹部３０とに、それぞれトルク伝達可能に内嵌する。
上記トルク伝達部材２２ａの構造の相違、並びに、この相違に伴って上記出力軸９ｂ及び上記カラー２３ａの構造を変えた点以外は、上述した実施の形態の第１例と同様であるから、同等部分に関する図示並びに説明は省略する。 [Second Example of Embodiment]
FIG. 8 shows a second example of an embodiment of the present invention corresponding to claims 1, 2, and 4. In the case of this example, the torque transmission buffer member 22a is constituted only by the elastic member 27a whose end face shape is a cross shape. Further, a driving side recess (not shown) having an end surface shape formed in a cross shape is formed on the distal end surface of the output shaft 9b, and a driven side recess portion 30 having an end surface shape formed in a cross shape is formed on the base end surface of the collar 23a. In the assembled state of the elastic shaft coupling 21a, both end portions in the axial direction of the torque transmitting buffer member 22a are fitted into the driving-side concave portion and the driven-side concave portion 30 so as to transmit torque.
Except for the difference in the structure of the torque transmission member 22a and the change in the structure of the output shaft 9b and the collar 23a in accordance with this difference, it is the same as the first example of the above-described embodiment. The illustration and description regarding the portion are omitted.

［実施の形態の第３例］
図９は、請求項１、２、４に対応する、本発明の実施の形態の第３例を示している。本例の場合には、トルク伝達用緩衝部材２２ｂを、端面形状が十字形である係合孔３１を中心部に設けた、筒状の弾性部材２７ｂのみで構成している。又、出力軸９ｃの先端面に、端面形状が十字形の駆動側凸部２５ａを、カラー２３ｂの基端面に端面形状が十字形の被駆動側凸部２４ａを、それぞれ形成している。そして、弾性軸継手２１ｂの組立状態では、上記トルク伝達用緩衝部材２２ｂの軸方向両端部を、上記駆動側凸部２５ａと上記被駆動側凸部２４ａとに、それぞれトルク伝達可能に外嵌する。
上記トルク伝達部材２２ｂの構造の相違、並びに、この相違に伴って上記出力軸９ｃ及び上記カラー２３ｂの構造を変えた点以外は、前述した実施の形態の第１例と同様であるから、同等部分に関する図示並びに説明は省略する。 [Third example of embodiment]
FIG. 9 shows a third example of an embodiment of the present invention corresponding to claims 1, 2, and 4. In the case of this example, the torque transmission buffer member 22b is constituted only by a cylindrical elastic member 27b having an engagement hole 31 whose end face shape is a cross shape at the center. Further, a drive-side convex portion 25a having a cross-shaped end surface is formed on the front end surface of the output shaft 9c, and a driven-side convex portion 24a having a cross-shaped end surface is formed on the base end surface of the collar 23b. In the assembled state of the elastic shaft coupling 21b, both end portions in the axial direction of the torque transmitting buffer member 22b are externally fitted to the driving-side convex portion 25a and the driven-side convex portion 24a so as to transmit torque. .
Except for the difference in the structure of the torque transmission member 22b and the change in the structure of the output shaft 9c and the collar 23b in accordance with this difference, it is the same as the first example of the above-described embodiment. The illustration and description regarding the portion are omitted.

［実施の形態の第４例］
図１０は、請求項１、２、４に対応する、本発明の実施の形態の第４例を示している。本例の場合には、トルク伝達用緩衝部材２２ｃを、基端面に端面形状が十字形である入力側凹部３２を、先端面に端面形状が十字形である出力側凸部３３を、それぞれ同心に設けた、弾性部材２７ｃのみで構成している。又、出力軸９ｃの先端面に、端面形状が十字形の駆動側凸部２５ａを、カラー２３ｂの基端面に端面形状が十字形の被駆動側凹部３０を、それぞれ形成している。そして、弾性軸継手２１ｃの組立状態では、上記駆動側凸部２５ａと上記入力側凹部３２とを、上記出力側凸部３３と上記被駆動側凹部３０とを、それぞれ嵌合させる。要するに本例の構造は、前述した実施の形態の第２例と上述した実施の形態の第３例とを組み合わせた如き構造を有する。凹凸の組み合わせを、入力側と出力側とで逆に（上記トルク伝達用緩衝部材２２ｃの軸方向を反転させて使用する構造を採用）しても良い。
上記トルク伝達部材２２ｃの構造の相違、並びに、この相違に伴って上記出力軸９ｃ及び上記カラー２３ｂの構造を変えた点以外は、前述した実施の形態の第１例と同様であるから、同等部分に関する図示並びに説明は省略する。 [Fourth Example of Embodiment]
FIG. 10 shows a fourth example of an embodiment of the present invention corresponding to claims 1, 2 and 4. In the case of this example, the torque transmission buffer member 22c is concentric with the input side concave portion 32 having a cross-shaped end surface on the base end surface and the output side convex portion 33 having a cross-shaped end surface on the distal end surface. It is comprised only by the elastic member 27c provided in. Further, a driving-side convex portion 25a having a cross-shaped end surface is formed on the front end surface of the output shaft 9c, and a driven-side concave portion 30 having a cross-shaped end surface is formed on the base end surface of the collar 23b. In the assembled state of the elastic shaft coupling 21c, the driving-side convex portion 25a and the input-side concave portion 32 are fitted together with the output-side convex portion 33 and the driven-side concave portion 30, respectively. In short, the structure of this example has a structure in which the second example of the above-described embodiment and the third example of the above-described embodiment are combined. The combination of unevenness may be reversed between the input side and the output side (adopting a structure in which the axial direction of the torque transmission buffer member 22c is reversed).
Except for the difference in the structure of the torque transmission member 22c and the change in the structure of the output shaft 9c and the collar 23b in accordance with this difference, it is the same as the first example of the above-described embodiment. The illustration and description regarding the portion are omitted.

［実施の形態の第５例］
図１１〜１３は、請求項１、３、４に対応する、本発明の実施の形態の第５例を示している。本例の場合には、トルク伝達用緩衝部材２２ｄを筒状に、カラー２３ｃを有底筒状に、それぞれ構成している。このうちのトルク伝達用緩衝部材２２ｄは、弾性材を射出成形して成る弾性部材２７ｄのみで構成したもので、内外両周面の端面形状を、何れも十字形乃至略十字形としている。又、上記カラー２３ｃの内周面は、上記トルク伝達用緩衝部材２２ｄを回転方向のがたつきなく内嵌できる様に、端面形状を略十字形としている。そして、弾性軸継手２１ｄの組立状態では、上記トルク伝達用緩衝部材２２ｄを上記カラー２３ｃのうちの筒部に内嵌すると共に、このトルク伝達用緩衝部材２２ｄに出力軸９ｃの先端面に設けた駆動側凸部２５ａを内嵌する。 [Fifth Example of Embodiment]
FIGS. 11 to 13 show a fifth example of the embodiment of the invention corresponding to claims 1, 3 and 4. In the case of this example, the torque transmission buffer member 22d is formed in a cylindrical shape, and the collar 23c is formed in a bottomed cylindrical shape. Among these, the torque transmission buffer member 22d is constituted only by an elastic member 27d formed by injection molding of an elastic material, and the end surface shape of both the inner and outer peripheral surfaces is a cross shape or a substantially cross shape. Further, the inner peripheral surface of the collar 23c has a substantially cross-shaped end surface so that the torque transmitting buffer member 22d can be fitted in without looseness in the rotational direction. In the assembled state of the elastic shaft coupling 21d, the torque transmission buffer member 22d is fitted into the cylindrical portion of the collar 23c, and the torque transmission buffer member 22d is provided on the distal end surface of the output shaft 9c. The drive side convex part 25a is fitted inside.

この様な本例の構造は、先に述べた実施の形態の第１〜３例の構造に比べて、軸方向寸法の短縮を図り易い。尚、本例の構造は、前述の図１６に示した先発明に係る構造と類似するが、第二スプライン軸部１７（図１６参照）に代えて上記トルク伝達用緩衝部材２２ｄと上記カラー２３ｃとを使用する分、これら各部材２２ｄ、２３ｃの小型化、これら各部材２２ｄ、２３ｃの加工の容易化を図り易くなる。又、各部材２２ｄ、２３ｃの材質、性状を適切に組み合わせて最良の性能を発揮させる事が容易になる等、設計の自由度が向上する。
上記トルク伝達部材２２ｄの構造の相違、並びに、この相違に伴って上記出力軸９ｃ及び上記カラー２３ｃの構造を変えた点以外は、前述した実施の形態の第１例と同様であるから、同等部分に関する図示並びに説明は省略する。 Such a structure of this example can easily reduce the axial dimension as compared with the structures of the first to third examples of the embodiment described above. The structure of this example is similar to the structure according to the previous invention shown in FIG. 16, but the torque transmission buffer member 22d and the collar 23c are replaced with the second spline shaft portion 17 (see FIG. 16). Therefore, it becomes easy to reduce the size of each of the members 22d and 23c and facilitate the processing of the members 22d and 23c. In addition, the degree of freedom in design is improved, such as making it possible to achieve the best performance by appropriately combining the materials and properties of the members 22d and 23c.
Except for the difference in the structure of the torque transmission member 22d and the change in the structure of the output shaft 9c and the collar 23c in accordance with this difference, it is the same as the first example of the above-described embodiment. The illustration and description regarding the portion are omitted.

図示の各例では、ウォーム軸６の側にスプライン孔１０ａを、出力軸９の側にスプライン軸部１１ａを、それぞれ形成した構造に就いて示した。これに対して、本発明を実施する場合に、ウォーム軸６の側にスプライン軸部１１ａを、出力軸９の側にスプライン孔１０ａを、それぞれ形成する事もできる。
又、本発明の弾性軸継手は、１対の回転軸同士の間で両方向のトルクを伝達する部分であれば、電動式パワーステアリング装置に限らず、他の回転機械装置に組み込んで実施する事もできる。
更に、各実施の形態の構造を得る為に、カラーと弾性部材とは、必ずしも別体としておく必要はない。これらカラーと弾性部材とを、溶着、接着等により、入力軸とスプライン軸との間での組み付け前に予め結合固定したり、それぞれの射出成形時に、二色成形により一体に造っても良い。 In each of the illustrated examples, the spline hole 10a is formed on the worm shaft 6 side and the spline shaft portion 11a is formed on the output shaft 9 side. On the other hand, when the present invention is carried out, the spline shaft portion 11a can be formed on the worm shaft 6 side, and the spline hole 10a can be formed on the output shaft 9 side.
In addition, the elastic shaft coupling of the present invention is not limited to the electric power steering device, as long as it is a portion that transmits torque in both directions between a pair of rotating shafts. You can also.
Furthermore, in order to obtain the structure of each embodiment, the collar and the elastic member are not necessarily separated from each other. The collar and the elastic member may be bonded and fixed in advance before assembling between the input shaft and the spline shaft by welding, bonding, or the like, or may be integrally formed by two-color molding at the time of each injection molding.

本発明の実施の形態の第１例を示す部分断面図。The fragmentary sectional view which shows the 1st example of embodiment of this invention. 図１のＡ部拡大図。The A section enlarged view of FIG. 一部を省略して示す、図２の拡大Ｂ−Ｂ断面図。The expanded BB sectional drawing of Drawing 2 which omits and shows a part. 同拡大Ｃ−Ｃ断面図。The expanded CC sectional drawing. 同拡大Ｄ−Ｄ断面図。The expanded DD sectional drawing. 同拡大Ｅ−Ｅ断面図。The expanded EE sectional drawing. 弾性軸継手部分の分解斜視図。The disassembled perspective view of an elastic shaft coupling part. 本発明の実施の形態の第２例を示す、図７と同様の図。The figure similar to FIG. 7 which shows the 2nd example of embodiment of this invention. 同第３例を示す、図７と同様の図。The figure similar to FIG. 7 which shows the 3rd example. 同第４例を示す、図７と同様の図。The figure similar to FIG. 7 which shows the 4th example. 同第５例を示す、図２と同様の図。The figure similar to FIG. 2 which shows the 5th example. 一部を省略して示す、図１１の拡大Ｆ−Ｆ断面図。The expanded FF sectional view of Drawing 11 which omits and shows a part. 同じく、図７と同様の図。Similarly, the same figure as FIG. 弾性軸継手が組み込まれる電動式パワーステアリング装置を備えた操舵装置の１例を示す、部分切断側面図。The partial cutting side view which shows an example of the steering device provided with the electric power steering device in which an elastic shaft coupling is integrated. 図１４の拡大Ｇ−Ｇ断面図。The expanded GG sectional drawing of FIG. 先発明に係る弾性軸継手を構成するスプライン軸とトルク伝達用緩衝部材との分解斜視図（ａ）及び組み立てた状態の斜視図（ｂ）。The disassembled perspective view (a) of the spline shaft which comprises the elastic shaft coupling which concerns on a prior invention, and the buffer member for torque transmission, and the perspective view (b) of the assembled state.

Explanation of symbols

１ステアリングホイール
２ステアリングシャフト
３ハウジング
４ウォームホイール
５ウォーム歯
６ウォーム軸
７ウォーム
８電動モータ
９、９ａ、９ｂ、９ｃ出力軸
１０、１０ａスプライン孔
１１、１１ａスプライン軸部
１２ａ、１２ｂ転がり軸受
１３押圧駒
１４コイルばね
１５ウォーム式減速機
１６第一スプライン軸部
１７第二スプライン軸部
１８非円形柱部
１９ステアリングコラム
２０ステアリングギヤユニット
２１、２１ａ、２１ｂ、２１ｃ、２１ｄ弾性軸継手
２２、２２ａ、２２ｂ、２２ｃ、２２ｄトルク伝達用緩衝部材
２３、２３ａ、２３ｂ、２３ｃカラー
２４、２４ａ被駆動側凸部
２５、２５ａ駆動側凸部
２６ブッシュ
２７、２７ａ、２７ｂ、２７ｃ、２７ｄ弾性部材
２８入力側係合孔
２９出力側係合孔
３０被駆動側凹部
３１係合孔
３２入力側凹部
３３出力側凸部 DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Steering shaft 3 Housing 4 Worm wheel 5 Worm tooth 6 Worm shaft 7 Worm 8 Electric motor 9, 9a, 9b, 9c Output shaft 10, 10a Spline hole 11, 11a Spline shaft part 12a, 12b Rolling bearing 13 Pressing piece 14 Coil spring 15 Worm type reduction gear 16 First spline shaft portion 17 Second spline shaft portion 18 Non-circular column portion 19 Steering column 20 Steering gear units 21, 21a, 21b, 21c, 21d Elastic shaft couplings 22, 22a, 22b, 22c, 22d Buffer member for torque transmission 23, 23a, 23b, 23c Collar 24, 24a Driven side convex part 25, 25a Drive side convex part 26 Bushing 27, 27a, 27b, 27c, 27d Elastic member 28 Input side engagement hole 2 Output side engagement hole 30 driven side recesses 31 engaging hole 32 input side recess 33 the output-side protrusion

Claims

In order to transmit torque between the ends of a pair of rotating shafts arranged in series with each other in the axial direction, an inner opening provided on the end surface of one of the rotating shafts. A spline hole having a female spline portion formed on the peripheral surface, and a spline shaft portion having a male spline portion formed on the outer peripheral surface provided at an end portion of the other rotary shaft of the two rotary shafts. In the elastic shaft joint that enables torque to be transmitted between the two rotating shafts by engaging the shaft portion with the spline hole, the spline shaft portion is located near the opening of the spline hole. The collar with the second male spline part on the outer peripheral surface is engaged with the back of the spline hole without backlash in the rotational direction. , With this color A torque transmission buffer member made of an elastic material and elastically deformable in the torque transmission direction is provided between the spline shaft portion and the torque transmission buffer member and the tip portion of the spline shaft portion. An elastic shaft coupling wherein the torque transmission buffer member and the collar are engaged so as to be able to transmit torque while being engaged so as to be able to transmit.

A torque transmission buffer member is disposed between the tip end surface of the spline shaft portion and the base end surface of the collar at an axially intermediate portion of the spline hole. The tip portion of the spline shaft portion and the torque transmission buffer member The elastic shaft coupling according to claim 1, wherein the base end portion and the tip end portion of the torque transmission buffer member and the base end portion of the collar are engaged with each other so as to be able to transmit torque.

The outer peripheral surface of the torque transmitting buffer member and the inner peripheral surface of the collar are engaged with each other so that torque can be transmitted, and the engagement formed on the inner peripheral surface of the torque transmitting buffer member and the tip surface of the spline shaft portion. The elastic shaft coupling according to claim 1, wherein the convex portion is engaged with the concave and convex portions so that torque can be transmitted.

A housing that is supported by a fixed portion and does not rotate; a rotating shaft that is rotatably provided to the housing and is rotated by an operation of a steering wheel; A worm wheel that is supported concentrically with the rotary shaft inside the housing and rotates together with the rotary shaft, and a worm tooth is provided at an axially intermediate portion of the worm shaft. In a state where the worm teeth are engaged with the worm wheel, both end portions in the axial direction of the worm shaft are rotatably supported with respect to the housing by bearings, and an electric motor for rotationally driving the worm, A joint device that is provided between the distal end portion of the output shaft of the electric motor and the proximal end portion of the worm shaft and transmits torque between the two shafts. In the electric power steering apparatus provided with bets, the joint device, an electric power steering apparatus, characterized in that the elastic coupling according to any one of claims 1 to 3.