JP2010007713A

JP2010007713A - Elastic shaft coupling and electric power steering device

Info

Publication number: JP2010007713A
Application number: JP2008165272A
Authority: JP
Inventors: Toshiichi Kajikawa; 敏一梶川
Original assignee: NSK Ltd
Current assignee: NSK Ltd
Priority date: 2008-06-25
Filing date: 2008-06-25
Publication date: 2010-01-14
Anticipated expiration: 2028-06-25
Also published as: JP5131054B2

Abstract

<P>PROBLEM TO BE SOLVED: To accomplish a structure having excellent transient characteristics when torque transmission is started. <P>SOLUTION: Elastic members 26, 26 are held between a circumferential side of driving side projections 21, 21 of a driving side transmission member 18, and a circumferential side of driven side projection 24, 24 of driven side transmission member 19, respectively. Torque is transmitted via each elastic member 26, 26. The elastic member 26, 26 is covered by covering a first core material 27 made of a comparatively hard elastic substance with a second covering section 28 made of a comparatively soft elastic substance. Out of these, the covering section 28 is brought into contact with the circumferential side of the first and second projections 21, 24. When the torque is transmitted, the core material 27 starts elastically deforming after the covering section 28 is elastically deformed to some extent in the compression direction. Therefore, the elastic member can have excellent transient characteristics. <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、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 and the worm shaft of the speed reducer constituting such an electric power steering device to prevent the driver from feeling uncomfortable during steering. Meanwhile, 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、近年普及し始めている。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。但し、ウォーム減速機の場合、何らの対策も施さないと、上記ウォームと上記ウォームホイールとの噛合部に存在するバックラッシュに基づき、上記回転軸の回転方向を変える際に、歯打ち音と呼ばれる不快な異音が発生する場合がある。 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. In addition, an electric power steering apparatus that uses an electric motor as an auxiliary power source in such a power steering apparatus has begun to spread in recent years. 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. However, in the case of a worm reducer, if no measures are taken, it is called a rattling sound when changing the rotation direction of the rotating shaft based on the backlash existing in the meshing portion of the worm and the worm wheel. Unpleasant noise may occur.

この様な歯打ち音の発生を抑えられる構造として従来から、特許文献１〜３に記載されている様に、ばね等の弾性部材によりウォームをウォームホイールに向け弾性的に押圧する事が考えられている。図９〜１０は、このうちの特許文献２に記載された電動式パワーステアリング装置の１例を示している。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、電動モータ７により回転駆動されるウォーム８の両端部は、深溝型玉軸受等の１対の転がり軸受９ａ、９ｂにより、上記ハウジング３内に回転自在に支持されている。更に、上記ウォーム軸６の先端部で上記転がり軸受９ａよりも突出した部分に押圧駒１０を外嵌し、この押圧駒１０と上記ハウジング３との間に、コイルばね１１等の弾性部材を設けている。そして、このコイルばね１１により、上記押圧駒１０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、上記歯打ち音の発生を抑えている。 Conventionally, as described in Patent Documents 1 to 3, it is considered that the worm is elastically pressed toward the worm wheel by an elastic member such as a spring as a structure that can suppress the generation of such rattling noise. ing. 9 to 10 show an example of the electric power steering apparatus described in Patent Document 2 among them. A front end portion of a 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. Worm teeth 5 meshing with the worm wheel 4 are provided in the axial direction intermediate portion of the worm shaft 6, and both ends of the worm 8 driven to rotate by the electric motor 7 are paired with a pair of rolling bearings 9 a such as a deep groove ball bearing, 9b is rotatably supported in the housing 3. Further, a pressing piece 10 is externally fitted to a portion protruding from the rolling bearing 9 a at the tip of the worm shaft 6, and an elastic member such as a coil spring 11 is provided between the pressing piece 10 and the housing 3. ing. The coil spring 11 presses the worm teeth 5 provided on the worm shaft 6 toward the worm wheel 4 through the pressing piece 10. With such a configuration, backlash between the worm teeth 5 and the worm wheel 4 is suppressed, and generation of the rattling noise 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７の出力軸１２の先端部と上記ウォーム軸６の基端部との結合部で発生する歯打ち音を抑える事はできない。この点に就いて、以下に説明する。上記電動モータ７の出力軸１２の先端部と上記ウォーム軸６の基端部とを回転力の伝達を自在に結合する為に、このウォーム軸６の基端部にスプライン孔１３を、このウォーム軸６の基端面に開口する状態で形成している。又、上記出力軸１２の先端部にスプライン軸部１４を形成している。そして、このスプライン軸部１４と上記スプライン孔１３とをスプライン係合させる事で、上記出力軸１２と上記ウォーム軸６とを、回転力の伝達を自在に結合している。 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 the tip of the output shaft 12 of the electric motor 7 and the worm The rattling noise generated at the joint with the base end of the shaft 6 cannot be suppressed. This point will be described below. A spline hole 13 is formed in the base end portion of the worm shaft 6 so that the tip end portion of the output shaft 12 of the electric motor 7 and the base end portion of the worm shaft 6 can be freely transmitted. It forms in the state opened to the base end surface of the axis | shaft 6. FIG. A spline shaft portion 14 is formed at the tip of the output shaft 12. The spline shaft portion 14 and the spline hole 13 are spline-engaged so that the output shaft 12 and the worm shaft 6 are freely coupled to transmit rotational force.

上記スプライン軸部１４と上記スプライン孔１３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１２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。特に、上述の図１０に示す様な構造により、上記ウォーム歯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る構造の場合には、上記ウォーム軸６を揺動変位させる必要上、上記スプライン係合部のバックラッシュを完全になくす事はできない。又、単なるスプライン係合部の場合、上記電動モータ７への通電開始に伴って上記出力軸１２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。 If the spline shaft portion 14 and the spline hole 13 are in spline engagement with no circumferential clearance (without backlash), the distal end portion of the output shaft 12 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 particular, in the case of a structure that suppresses backlash between the worm tooth 5 and the worm wheel 4 by the structure as shown in FIG. 10, the spline engagement is necessary because the worm shaft 6 needs to be oscillated and displaced. The joint backlash cannot be completely eliminated. In the case of a simple spline engaging portion, a large torque suddenly starts to be transmitted from the output shaft 12 to the worm shaft 6 with the start of energization of the electric motor 7. 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.

この様な不都合を発生するスプライン係合部に代えて、上記出力軸１２の先端部と上記ウォーム軸６の基端部とのトルク伝達部に、弾性部材を介してトルク伝達を行う弾性軸継手を組み込む事が考えられる。そして、電動式パワーステアリング装置を構成する電動モータ７の出力軸１２の先端部とウォーム軸６の基端部との間に組み込み可能な弾性軸継手として、特許文献４、５に記載されたものが知られている。これら特許文献４、５に記載された弾性軸継手は何れも、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、このトルクの方向に関して弾性変形可能な弾性部材を介して伝達する。 Instead of the spline engaging portion that causes such inconvenience, an elastic shaft coupling that transmits torque to the torque transmitting portion between the distal end portion of the output shaft 12 and the proximal end portion of the worm shaft 6 via an elastic member. Can be considered. Patent Documents 4 and 5 describe elastic shaft couplings that can be incorporated between the distal end portion of the output shaft 12 of the electric motor 7 constituting the electric power steering device and the proximal end portion of the worm shaft 6. It has been known. In any of the elastic shaft couplings described in Patent Documents 4 and 5, torque can be elastically deformed between ends of a pair of rotating shafts arranged in series with each other in the axial direction. It transmits via an elastic member.

この為に上記従来の弾性軸継手は、第一、第二両伝達部材と弾性部材とを備える。これら両伝達部材はそれぞれ、上記両回転軸の端部に、これら両回転軸と同心に支持される。又、これら両伝達部材のうちの相手側の回転軸に対向する面に、回転方向に関して間欠的に、それぞれこの相手側の回転軸に向け軸方向に突出する、それぞれ複数の第一、第二各突出部を設けている。そして、上記弾性部材を、各第一、第二突出部の円周方向側面同士の間に挟持している。又、特許文献４に記載された従来構造の場合には、上記各第一、第二突出部による上記弾性部材の圧縮状態を２段階に変える事で、この弾性部材の弾性変形状態をチューニングしている。更に、特許文献５に記載された従来構造の場合には、弾性の異なる２種類の弾性部材を設け、比較的弾性の小さい（軟らかい）弾性部材を或る程度押し潰してから、比較的弾性の大きい（硬い）弾性部材によるトルク伝達を行わせる様にしている。 For this purpose, the conventional elastic shaft coupling includes first and second transmission members and an elastic member. Both of these transmission members are supported concentrically with the two rotation shafts at the ends of the two rotation shafts. Further, a plurality of first and second members projecting in the axial direction toward the mating rotating shaft intermittently with respect to the rotating direction on the surface facing the mating rotating shaft of the two transmission members. Each protrusion is provided. And the said elastic member is clamped between the circumferential direction side surfaces of each 1st, 2nd protrusion part. In the case of the conventional structure described in Patent Document 4, the elastic deformation state of the elastic member is tuned by changing the compression state of the elastic member by the first and second protrusions in two stages. ing. Furthermore, in the case of the conventional structure described in Patent Document 5, two types of elastic members having different elasticity are provided, and a relatively small (soft) elastic member is crushed to some extent, and then a relatively elastic Torque is transmitted by a large (hard) elastic member.

但し、上記特許文献４、５に記載された従来構造の場合には、比較的小さなトルク伝達を行う状態から大きなトルク伝達を行う状態に移行する過程で、トルク伝達方向に関する弾性軸継手の剛性が急変動する（剛性が急に大きくなる）。即ち、上記特許文献４に記載された構造の場合には、弾性部材のうちで容積が小さい（トルク伝達に供される部分の断面積が狭い）部分が押し潰されてから、容積が大きい（トルク伝達に供される部分の断面積が広い）部分が押し潰され始める瞬間に、上記剛性の急変動が生じる。又、上記特許文献５に記載された構造の場合には、比較的弾性の小さい弾性部材を押し潰してから、比較的弾性の大きい弾性部材を押し潰し始める瞬間に、上記剛性の急変動が生じる。この結果、前述した様に、前記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し、運転者に違和感を与える可能性がある。 However, in the case of the conventional structures described in Patent Documents 4 and 5, the rigidity of the elastic shaft coupling in the torque transmission direction is reduced in the process of shifting from a state where relatively small torque is transmitted to a state where large torque is transmitted. Fluctuates rapidly (stiffness suddenly increases). That is, in the case of the structure described in Patent Document 4, the volume of the elastic member is large after the portion having a small volume (the cross-sectional area of the portion used for torque transmission is narrow) is crushed ( The sudden fluctuation of the rigidity occurs at the moment when the portion (the cross-sectional area of the portion subjected to torque transmission is wide) starts to be crushed. In the case of the structure described in Patent Document 5, the rigidity changes suddenly at the moment when the elastic member having relatively small elasticity is crushed and then the elastic member having relatively large elasticity is started to be crushed. . As a result, as described above, the force required to operate the steering wheel 1 is drastically reduced, which may cause the driver to feel uncomfortable.

特開２０００−４３７３９号公報JP 2000-43739 A 特開２００４−３０６８９８号公報JP 2004-306898 A 特表２００６−５１３９０６号公報JP-T-2006-513906 特開２００４−１４８９９０号公報JP 2004-148990 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、トルク伝達開始時の過渡特性が良好な弾性軸継手及び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。 The present invention has been invented in order to realize an elastic shaft coupling and an electric power steering apparatus having good transient characteristics at the start of torque transmission in view of the above-described circumstances.

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、例えば特許文献４、５に記載される等により従来から知られている弾性軸継手と同様に、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、このトルクの方向に関して弾性変形可能な弾性部材を介して伝達する為のものである。
この為に本発明の弾性軸継手は、第一、第二両伝達部材と、弾性部材とを備える。
このうちの第一伝達部材は、上記両回転軸のうちの一方の回転軸の端部に、この一方の回転軸と同心に支持されるもので、これら両回転軸のうちの他方の回転軸に対向する面に、回転方向に関して間欠的に、それぞれこの他方の回転軸に向け軸方向に突出する複数の第一突出部を備える。
又、上記第二伝達部材は、上記他方の回転軸の端部に、この他方の回転軸と同心に支持されるもので、上記一方の回転軸に対向する面に、回転方向に関して間欠的に、それぞれこの一方の回転軸に向け軸方向に突出する複数の第二突出部を備える。
更に、上記弾性部材は、これら各第二突出部の円周方向側面と上記各第一突出部の円周方向側面との間に挟持されている。 Of the elastic shaft coupling and electric power steering apparatus of the present invention, the invention of the elastic shaft coupling described in claim 1 is an elastic shaft coupling that has been conventionally known, for example, as described in Patent Documents 4 and 5. Similarly, torque is transmitted between ends of a pair of rotating shafts arranged in series with respect to the axial direction via elastic members that are elastically deformable with respect to the direction of the torque.
For this purpose, the elastic shaft coupling of the present invention includes both first and second transmission members and an elastic member.
The first transmission member is supported at the end of one of the two rotation shafts concentrically with the one rotation shaft, and the other rotation shaft of the two rotation shafts. Are provided with a plurality of first protrusions protruding in the axial direction toward the other rotation axis intermittently with respect to the rotation direction.
The second transmission member is supported at the end of the other rotation shaft concentrically with the other rotation shaft, and intermittently with respect to the rotation direction on the surface facing the one rotation shaft. , Each having a plurality of second protrusions protruding in the axial direction toward the one rotation shaft.
Further, the elastic member is sandwiched between the circumferential side surface of each of the second projecting portions and the circumferential side surface of each of the first projecting portions.

特に、本発明の弾性軸継手に於いては、上記弾性部材は、第一の弾性材製の芯材を、この第一の弾性材よりも軟らかい第二の弾性材製の被覆部で覆っている。そして、このうちの被覆部と、上記第一、第二各突出部の円周方向側面とを当接させている。 In particular, in the elastic shaft coupling of the present invention, the elastic member covers the core material made of the first elastic material with the covering portion made of the second elastic material, which is softer than the first elastic material. Yes. And the coating | coated part of these and the circumferential direction side surface of said 1st, 2nd each protrusion part are made to contact | abut.

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、上記第一、第二各突出部の円周方向側面同士の間に、それぞれが円柱状の弾性部材を、これら各弾性部材の軸方向端面をこれら各突出部の円周方向側面に突き合わせた状態で挟持する。そして、上記各弾性部材を、軸方向中央部から両端部に向かうに従って外径が小さくなる方向に傾斜した芯材と、この芯材よりも大きな軸方向寸法を有し、この芯材全体を覆った被覆部とから成るものとする。 When implementing the elastic shaft coupling of the present invention as described above, for example, as in the invention described in claim 2, each of the first and second protrusions has a circular shape between the circumferential side surfaces thereof. The columnar elastic members are held in a state where the axial end surfaces of the respective elastic members are abutted with the circumferential side surfaces of the respective protruding portions. Each of the elastic members has a core member that is inclined in a direction in which the outer diameter decreases from the central portion in the axial direction toward both ends, and has a larger axial dimension than the core member, and covers the entire core member. And a covering portion.

この様な請求項２に記載した発明を実施する場合に好ましくは、請求項３に記載した発明の様に、上記第一、第二各突出部の円周方向側面同士の間に存在する、複数の弾性部材を設置すべき空間に合わせて配置した、これら各弾性部材の周囲に、上記各突出部の外接円の直径以上の内径を有する連結環を設ける。そして、連結腕部によりこの連結環と上記各弾性部材とを連結する。 When carrying out the invention described in claim 2, preferably, as in the invention described in claim 3, it exists between the circumferential side surfaces of the first and second protrusions. A connecting ring having an inner diameter equal to or larger than the diameter of the circumscribed circle of each of the protrusions is provided around each elastic member, which is arranged in accordance with a space in which a plurality of elastic members are to be installed. And this connection ring and each said elastic member are connected with a connection arm part.

或は、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４に記載した発明の様に、上記第一、第二各突出部の円周方向側面同士の間に、それぞれが直方体状の弾性部材を、この円周方向に関するこれら各弾性部材の互いに反対側の２面を、上記各突出部の円周方向側面に突き合わせた状態で挟持する。そして、上記各弾性部材を、上記第一、第二両伝達部材の軸方向に関する幅が、上記円周方向の中央部から同じく両端部に向かうに従って小さくなる芯材と、この円周方向に関する幅が上記芯材よりも大きく、この芯材のうちで上記各突出部の円周方向側面に対向する部分の全体を覆った被覆部とから成るものとする。 Or, when implementing the elastic shaft coupling of the present invention as described above, for example, as in the invention described in claim 4, between the circumferential side surfaces of the first and second protrusions, Each of the elastic members each having a rectangular parallelepiped shape is sandwiched in a state in which the two opposite surfaces of each elastic member in the circumferential direction are abutted with the circumferential side surface of each protrusion. Then, each of the elastic members has a core material in which the width in the axial direction of the first and second transmission members decreases from the central portion in the circumferential direction toward both ends, and the width in the circumferential direction. Is larger than the core material, and is composed of a covering portion covering the entire portion of the core material facing the circumferential side surface of each protrusion.

この様な請求項４に記載した発明を実施する場合に好ましくは、請求項５に記載した発明の様に、上記第一、第二両伝達部材の径方向に関して、上記第一、第二各突出部の円周方向側面同士の間に存在する、複数の弾性部材を設置すべき空間に合わせて配置したこれら各弾性部材の内側に、外径が上記各突出部の内接円の直径以下である連結部を設ける。そして、上記径方向に関して上記各弾性部材の内端部をこの連結部の外周面に連結して、放射状に配列する。 When the invention described in claim 4 is carried out, preferably, as in the invention described in claim 5, the first and second transmission members are respectively in the radial direction of the first and second transmission members. Inside each of these elastic members that are arranged between the circumferential side surfaces of the protrusions and are arranged in accordance with the space in which the plurality of elastic members are to be installed, the outer diameter is equal to or less than the diameter of the inscribed circle of each of the protrusions. A connecting portion is provided. And the inner end part of each said elastic member is connected with the outer peripheral surface of this connection part regarding the said radial direction, and it arranges radially.

一方、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６に記載した電動式パワーステアリング装置の発明は、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。
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。
又、上記ウォームホイールは、上記ハウジングの内部でこの回転軸の一部に、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されている。
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て、これら両軸同士の間でトルクを伝達するもので、上述の様な、本発明の弾性軸継手である。 On the other hand, among the elastic shaft coupling and electric power steering device of the present invention, the invention of the electric power steering device according to claim 6 includes a housing, a rotating shaft, a worm wheel, a worm, an electric motor, A coupling device.
Of these, the housing is supported by a fixed portion and does not rotate.
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.
The worm wheel is supported on a part of the rotating shaft inside the housing and concentrically with the rotating shaft, and rotates together with the rotating shaft.
The worm is formed by providing a worm tooth at an intermediate portion of the worm shaft in the axial direction. With the worm tooth engaged with the worm wheel, both end portions in the axial direction of the worm shaft are respectively attached to the housing by bearings. On the other hand, it is supported rotatably.
The electric motor is for rotating the worm.
Furthermore, 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 the two shafts. The elastic shaft coupling of the present invention.

上述の様に構成する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によれば、トルク伝達開始時からトルク変動時（上昇時及び低下時）の過渡特性を良好にできる。この様に、トルク伝達開始時の過渡特性が良好になる事は、弾性部材を、比較的硬い第一の弾性材と、比較的軟らかい第二の弾性材との、二重構造とする事により図れる。
即ち、本発明の弾性軸継手の場合には、上記第一の弾性材製の芯材を上記第二の弾性材製の被覆部で覆っている為、上記トルク伝達の開始時に、第一、第二各突出部の円周方向側面同士の間で上記弾性部材を押圧した場合、先ず、被覆部を構成する上記第二の弾性材が圧縮方向に弾性変形する。この為、トルク伝達開始の瞬間に急に大きなトルクが伝達され始める事を防止できる。そして、上記第二の弾性材が或る程度圧縮方向に弾性変形した後に、上記芯材を構成する上記第一の弾性材が圧縮方向に弾性変形し始める。これら第一、第二の弾性材は、上記トルクの伝達方向でもある、圧縮方向に関して互いに直列に配置されている為、上記第二の弾性材の圧縮変形が進んだ状態から上記第一の弾性材の圧縮変形が開始される過程で、上記弾性部材全体としての、圧縮方向に関する剛性が急変動する事はない。この為、伝達すべきトルクが上昇する過程でも、伝達されるトルクが急変動する事を防止できる。
これらにより、過渡特性を全体として良好にできて、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。 According to the elastic shaft coupling and the electric power steering apparatus of the present invention configured as described above, it is possible to improve the transient characteristics from the time of torque transmission to the time of torque fluctuation (at the time of increase and decrease). In this way, the transient characteristic at the start of torque transmission is improved by making the elastic member a double structure of a relatively hard first elastic material and a relatively soft second elastic material. I can plan.
That is, in the case of the elastic shaft coupling of the present invention, since the core material made of the first elastic material is covered with the covering portion made of the second elastic material, at the start of the torque transmission, When the elastic member is pressed between the circumferential side surfaces of the second projecting portions, first, the second elastic material constituting the covering portion is elastically deformed in the compression direction. For this reason, it is possible to prevent sudden transmission of a large torque at the moment of starting torque transmission. Then, after the second elastic material is elastically deformed to some extent in the compression direction, the first elastic material constituting the core material begins to elastically deform in the compression direction. Since these first and second elastic materials are arranged in series with respect to the compression direction, which is also the transmission direction of the torque, the first elastic material from the state in which the compression deformation of the second elastic material has advanced. In the process of starting the compressive deformation of the material, the rigidity of the elastic member as a whole in the compression direction does not change suddenly. For this reason, even when the torque to be transmitted rises, it is possible to prevent the transmitted torque from changing suddenly.
As a result, the transient characteristics can be improved as a whole, and the driver who operates the steering wheel can be made uncomfortable.

［実施の形態の第１例］
図１〜４は、請求項１〜３、６に対応する、本発明の実施の形態の第１例を示している。本例の場合には、電動式パワーステアリング装置を構成する電動モータ７の出力軸１２ａの先端部と、ウォーム式減速機を構成するウォーム軸６ａの基端部との間に、本例の特徴である弾性軸継手１５を設けている。そして、上記出力軸１２ａから上記ウォーム軸６ａにトルクを、起動時及びトルク変動時に緩衝作用を持たせた状態で（上記電動モータ７の起動時にトルク伝達が急激に開始されない様に、トルク変動時にウォーム軸６ａに伝達されるトルクが急変動しない様に、過渡特性を良好にした状態で）、伝達自在としている。上記弾性軸継手１５を設ける為に、上記出力軸１２ａの先端部に駆動側セレーション部１６を、上記ウォーム軸６ａの基端部に被駆動側セレーション部１７を、それぞれ設けている。上記弾性軸継手１５を除く、上記電動式パワーステアリング装置の構成及び作用は、前述の図９〜１０に示した構造を含め、従来から広く知られている電動式パワーステアリング装置と同様であるから説明を省略し、以下、上記弾性軸継手１５の構成及び作用に就いて説明する。又、以下の説明で、径方向、周方向、軸方向とはこの弾性軸継手１５（の構成各部材）の径方向、周方向、軸方向を指す。 [First example of embodiment]
1 to 4 show a first example of an embodiment of the present invention corresponding to claims 1 to 3 and 6. In the case of this example, the feature of this example is between the distal end portion of the output shaft 12a of the electric motor 7 constituting the electric power steering device and the proximal end portion of the worm shaft 6a constituting the worm type reduction gear. The elastic shaft coupling 15 is provided. Then, torque is applied from the output shaft 12a to the worm shaft 6a at the time of start-up and torque fluctuation (when torque fluctuation occurs so that torque transmission does not start abruptly when the electric motor 7 starts up). In order to prevent the torque transmitted to the worm shaft 6a from fluctuating suddenly, the torque can be transmitted freely (with excellent transient characteristics). In order to provide the elastic shaft joint 15, a driving side serration portion 16 is provided at the distal end portion of the output shaft 12a, and a driven side serration portion 17 is provided at the proximal end portion of the worm shaft 6a. Since the configuration and operation of the electric power steering apparatus excluding the elastic shaft coupling 15 are the same as those of the conventionally known electric power steering apparatus including the structures shown in FIGS. The description will be omitted, and the configuration and operation of the elastic shaft coupling 15 will be described below. In the following description, the radial direction, the circumferential direction, and the axial direction refer to the radial direction, the circumferential direction, and the axial direction of the elastic shaft coupling 15 (constituting members).

上記弾性軸継手１５は、特許請求の範囲に記載した第一伝達部材に相当する駆動側伝達部材１８と、同じく第二伝達部材に相当する被駆動側伝達部材１９とを備える。このうちの駆動側伝達部材１８は、上記出力軸１２ａの先端部に外嵌固定自在な円板状の駆動側基板部２０の軸方向片面の径方向外寄り部分の円周方向複数個所（図示の例では円周方向等間隔４箇所）から、それぞれが特許請求の範囲に記載した第一突出部である駆動側突出部２１、２１を、軸方向に突出形成している。周方向に関する、これら各駆動側突出部２１、２１の幅寸法は、径方向内方で小さく、径方向外方で大きくしている。即ち、軸方向から見た、上記各駆動側突出部２１、２１の端面形状を、径方向内側程幅が狭くなる扇形としている。又、上記駆動側基板部２０の中心部には、上記駆動側セレーション部１６とセレーション係合する、駆動側セレーション孔２２を形成している。 The elastic shaft coupling 15 includes a driving side transmission member 18 corresponding to the first transmission member described in the claims, and a driven side transmission member 19 corresponding to the second transmission member. Of these, the drive-side transmission member 18 has a plurality of circumferentially-positioned portions (in the figure) on the radially outward portion of one axial surface of the disk-like drive-side substrate portion 20 that can be fitted and fixed to the distal end portion of the output shaft 12a. In this example, drive-side projecting portions 21 and 21 that are first projecting portions described in the claims are formed so as to project in the axial direction. The width dimensions of the drive-side protrusions 21 and 21 in the circumferential direction are small in the radial direction and large in the radial direction. That is, when viewed from the axial direction, the end face shape of each of the drive side protrusions 21 and 21 is a sector shape whose width becomes narrower inward in the radial direction. Further, a drive side serration hole 22 is formed in the center of the drive side substrate portion 20 to engage with the drive side serration portion 16.

一方、上記被駆動側伝達部材１９は、上記駆動側伝達部材１８と同形状の部材を、軸方向に関して反転させた状態で使用する。即ち、上記被駆動側伝達部材１９は、上記駆動側基板部２０と同形状の被駆動側基板部２３と、上記各駆動側突出部２１、２１と同形状であり、特許請求の範囲に記載した第二突出部に相当する被駆動側突出部２４、２４とを備える。そして、上記被駆動側基板部２３の中心部に、前記駆動側セレーション部１７とセレーション係合する、被駆動側セレーション孔２５を形成している。 On the other hand, the driven-side transmission member 19 uses a member having the same shape as the driving-side transmission member 18 in a state of being inverted with respect to the axial direction. That is, the driven-side transmission member 19 has the same shape as the driven-side substrate portion 23 having the same shape as the driving-side substrate portion 20 and the driving-side protruding portions 21 and 21, and is described in the claims. And driven side protrusions 24 and 24 corresponding to the second protrusions. A driven-side serration hole 25 that engages with the driving-side serration portion 17 is formed in the center of the driven-side substrate portion 23.

それぞれが上述の様な構成を有する、上記駆動側伝達部材１８と上記被駆動側伝達部材１９とは、上記各駆動側突出部２１、２１と上記各被駆動側突出部２４、２４とを合計した数（図示の例では８個）の弾性部材２６、２６を介して組み合わせている。これら各弾性部材２６、２６は、第一の弾性材製の芯材２７を、第二の弾性材製の被覆部２８により全体を覆う事で、外面形状を円柱状としている。上記芯材２７の形状は、軸対称の略卵形状で、軸方向中央部から両端部に向かうに従って外径が小さくなる方向に傾斜している。又、軸方向両端面は、部分球面状の凸面としている。又、上記被覆部２８は、上記芯材２７よりも大きな軸方向寸法を有し、この芯材２７全体を覆っている。この被覆部２８を構成する第二の弾性材は、この芯材２７を構成する第一の弾性材よりも軟らかい（弾性係数が低い）。 The drive-side transmission member 18 and the driven-side transmission member 19 each having the above-described configuration are the sum of the drive-side protrusions 21 and 21 and the driven-side protrusions 24 and 24. These are combined through the elastic members 26, 26 (eight in the illustrated example). Each of these elastic members 26 and 26 has a cylindrical outer surface shape by covering the entire core material 27 made of a first elastic material with a covering portion 28 made of a second elastic material. The shape of the core material 27 is an axisymmetric substantially egg shape, and is inclined in a direction in which the outer diameter decreases from the central portion in the axial direction toward both ends. Further, both end surfaces in the axial direction are partially spherical convex surfaces. The covering portion 28 has a larger axial dimension than the core material 27 and covers the entire core material 27. The second elastic material constituting the covering portion 28 is softer (lower elastic coefficient) than the first elastic material constituting the core material 27.

上記第一、第二の弾性材の組み合わせは、前記弾性軸継手１５の大きさ（直径を含むサイズ）、この弾性軸継手１５により伝達すべきトルクの最大値等に応じて適宜選択する。例えば、伝達すべきトルクが大きい場合には、第一の弾性材として、弾性係数が高い弾性材である合成樹脂を、第二の弾性材として、この合成樹脂に比べれば弾性係数が低い弾性材である硬質ゴムを、それぞれ使用できる。これに対して、伝達すべきトルクが小さい場合には、第一の弾性材として硬質ゴムを、第二の弾性材として軟質ゴムを、それぞれ使用できる。その他、ビニル等、ゴム以外のエラストマーを、何れかの弾性材として使用する事もできる。又、上記芯材２７の軸方向長さと上記被覆部２８の軸方向長さとの差に関しても、適宜設定可能である。この差を小さくすれば、図４の（Ａ）に示す様に、上記被覆部２８の両端部で上記芯材２７からはみ出した部分の厚さｔが小さくなり、上記差を大きくすれば、図４の（Ｂ）に示す様に、このはみ出した部分の厚さＴが大きくなる。このはみ出した部分の厚さｔ、Ｔの大きさは、上記第一、第二の弾性材の硬度や、上記弾性軸継手１５に要求する緩衝性能に応じて、設計的に定める。 The combination of the first and second elastic members is appropriately selected according to the size (including the diameter) of the elastic shaft coupling 15 and the maximum value of torque to be transmitted by the elastic shaft coupling 15. For example, when the torque to be transmitted is large, a synthetic resin that is an elastic material having a high elastic coefficient is used as the first elastic material, and an elastic material that has a lower elastic coefficient than the synthetic resin is used as the second elastic material. Each of the hard rubbers can be used. On the other hand, when the torque to be transmitted is small, hard rubber can be used as the first elastic material, and soft rubber can be used as the second elastic material. In addition, elastomers other than rubber, such as vinyl, can be used as any elastic material. Further, the difference between the axial length of the core member 27 and the axial length of the covering portion 28 can be set as appropriate. If this difference is reduced, as shown in FIG. 4 (A), the thickness t of the portion protruding from the core material 27 at both ends of the covering portion 28 is reduced. As shown in FIG. 4B, the thickness T of the protruding portion is increased. The thicknesses t and T of the protruding portions are determined by design according to the hardness of the first and second elastic materials and the buffer performance required for the elastic shaft coupling 15.

それぞれが上述の様な芯材２７と被覆部２８とから成る弾性部材２６、２６は、単一円弧上に、それぞれの中心軸をこの単一円弧の接線方向に一致させた状態で、円周方向に関して等間隔に配置している。更に、上記各弾性部材２６、２６は、これら各弾性部材２６、２６の周囲に配置された連結環２９により、互いに連結している。この連結環２９の内径は、前記駆動側、被駆動側各突出部２１、２４の外接円の直径以上であり、上記各弾性部材２６、２６は、それぞれの軸方向中間部と上記連結環２９の内周面との間に設けた連結腕部３０、３０により、この連結環２９に連結されている。 The elastic members 26 and 26 each composed of the core material 27 and the covering portion 28 as described above are arranged on a single circular arc in a state where the respective central axes coincide with the tangential direction of the single circular arc. It arrange | positions at equal intervals regarding a direction. Further, the elastic members 26 and 26 are connected to each other by a connecting ring 29 disposed around the elastic members 26 and 26. The inner diameter of the connecting ring 29 is equal to or larger than the diameter of the circumscribed circle of the driving side and driven side projections 21 and 24, and the elastic members 26 and 26 are connected to the axially intermediate portion and the connecting ring 29. It is connected with this connection ring 29 by the connection arm parts 30 and 30 provided between the inner peripheral surfaces of these.

この様な連結環２９により互いに連結された、上記各弾性部材２６、２６は、図２→図３に示す様に、前記駆動側、被駆動側両伝達部材１８、１９と組み合わせて、前記弾性軸継手１５とする。即ち、上記各駆動側突出部２１、２１と上記各被駆動側突出部２４、２４とを、互いの円周方向側面同士の間に上記各弾性部材２６、２６を挟持しつつ円周方向に関して互いに重畳させる。この状態でこれら各弾性部材２６、２６の軸方向両端面（上記両伝達部材１８、１９の円周方向に関する両端面）を、上記各突出部２１、２４の円周方向両側面に当接させる。この様にして上記駆動側、被駆動側両伝達部材１８、１９と上記各弾性部材２６、２６とを組み合わせて成る上記弾性軸継手１５は、前記駆動側セレーション孔２２を前記駆動側セレーション部１６と、前記被駆動側セレーション孔２５を前記被駆動側セレーション部１７と、それぞれセレーション係合させる事で、前記出力軸１２ａの先端部と前記ウォーム軸６ａの基端部との間に組み付ける。尚、上記弾性軸継手１５の中立状態で、上記各突出部２１、２４の互いに対向する円周方向側面同士は、互いに平行である。 The elastic members 26 and 26 connected to each other by such a connecting ring 29 are combined with the drive side and driven side transmission members 18 and 19 as shown in FIGS. A shaft coupling 15 is used. That is, the drive-side protrusions 21 and 21 and the driven-side protrusions 24 and 24 are related to the circumferential direction while holding the elastic members 26 and 26 between the circumferential side surfaces thereof. Superimpose each other. In this state, both end surfaces in the axial direction of the elastic members 26 and 26 (both end surfaces in the circumferential direction of the transmission members 18 and 19) are brought into contact with both side surfaces in the circumferential direction of the protrusions 21 and 24. . In this way, the elastic shaft coupling 15 formed by combining both the driving side and driven side transmission members 18 and 19 and the elastic members 26 and 26 includes the driving side serration hole 22 and the driving side serration portion 16. Then, the driven side serration hole 25 and the driven side serration portion 17 are engaged with each other to be assembled between the distal end portion of the output shaft 12a and the proximal end portion of the worm shaft 6a. In addition, in the neutral state of the elastic shaft joint 15, the mutually facing circumferential side surfaces of the projecting portions 21 and 24 are parallel to each other.

上記出力軸１２ａと上記ウォーム軸６ａとの間でトルクを伝達する際には、上記各弾性部材２６、２６が弾性変形しつつ、このトルクを伝達する。この為、トルク伝達開始時からトルク変動時（上昇時及び低下時）の過渡特性を良好にできる。特に、上記各弾性部材２６、２６は、比較的硬い第一の弾性材製の芯材２７を、比較的軟らかい第二の弾性材製の被覆部２８により覆った二重構造とし、このうちの被覆部２８を上記各突出部２１、２４の円周方向両側面に当接させている事により図れる。この理由に就いて、以下に説明する。 When torque is transmitted between the output shaft 12a and the worm shaft 6a, the elastic members 26, 26 are elastically deformed and transmit this torque. For this reason, it is possible to improve the transient characteristics from the start of torque transmission to the time of torque fluctuation (at the time of increase and decrease). In particular, each of the elastic members 26, 26 has a double structure in which a relatively hard first elastic material core material 27 is covered with a relatively soft second elastic material covering portion 28, of which This can be achieved by bringing the covering portion 28 into contact with both circumferential sides of the protruding portions 21 and 24. The reason will be described below.

上記出力軸１２ａと上記ウォーム軸６ａとの間でトルクを伝達する際には、上記各弾性部材２６、２６のうち、上記各駆動側突出部２１、２１の回転方向前側面と上記各被駆動側各突出部２４、２４の回転方向後側面との間に挟持された（全弾性部材２６、２６のうちの半分の）弾性部材２６、２６を、それぞれの軸方向に圧縮する。この様に、これら各弾性部材２６、２６を圧縮し始める際には、先ず、軟らかい上記被覆部２８が圧縮方向に弾性変形する。この為、トルク伝達開始の瞬間に急に大きなトルクが伝達され始める事を防止できる。そして、上記被覆部２８が或る程度圧縮方向に弾性変形するに伴って、硬い上記芯材２７も、圧縮方向に徐々に弾性変形し始める。これら芯材２７と被覆部２８とは、上記トルクの伝達方向でもある、圧縮方向に関して互いに直列に配置されている為、上記被覆部２８の圧縮変形が進んだ状態から上記芯材２７の圧縮変形が開始される過程で、上記各弾性部材２６、２６全体としての、圧縮方向に関する剛性が急変動する事はない。この為、伝達すべきトルクが上昇する過程でも、伝達されるトルクが急変動する事を防止できる。伝達すべきトルクが低下する過程では、逆の動作により、伝達されるトルクが急変動する事を防止できる。
これらにより、過渡特性を全体として良好にできて、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。 When torque is transmitted between the output shaft 12a and the worm shaft 6a, among the elastic members 26, 26, the front side surfaces in the rotational direction of the drive-side protrusions 21 and 21 and the driven parts. The elastic members 26, 26 (half of all the elastic members 26, 26) sandwiched between the side protrusions 24, 24 in the rotational direction rear side surface are compressed in the respective axial directions. As described above, when the elastic members 26 are started to be compressed, first, the soft covering portion 28 is elastically deformed in the compression direction. For this reason, it is possible to prevent sudden transmission of a large torque at the moment of starting torque transmission. As the covering portion 28 is elastically deformed to some extent in the compression direction, the hard core material 27 also starts to be elastically deformed gradually in the compression direction. Since the core material 27 and the covering portion 28 are arranged in series with each other in the compression direction, which is also the transmission direction of the torque, the compression deformation of the core material 27 from a state in which the compression deformation of the covering portion 28 has progressed. In the process of starting, the rigidity in the compression direction of the elastic members 26, 26 as a whole does not change suddenly. For this reason, even when the torque to be transmitted rises, it is possible to prevent the transmitted torque from changing suddenly. In the process of reducing the torque to be transmitted, it is possible to prevent the transmitted torque from changing suddenly due to the reverse operation.
As a result, the transient characteristics can be improved as a whole, and the driver who operates the steering wheel can be made uncomfortable.

［実施の形態の第２例］
図５〜８は、請求項１、４〜６に対応する、本発明の実施の形態の第２例を示している。本例の弾性軸継手１５ａは、弾性部材２６ａの構造が、上述した第１例と異なる。駆動側、被駆動側両伝達部材１８、１９の構造に関しては、基本的には、この第１例と同様である。本例の弾性軸継手１５ａの場合には、上記両伝達部材１８、１９に設けた、駆動側、被駆動側各突出部２１、２４の円周方向側面同士の間に、それぞれが直方体状の弾性部材２６ａ、２６ａを挟持している。上記弾性軸継手１５ａの構成各部材１８、１９、２６ａを組み立てた後の上記両伝達部材１８、１９の中立状態で、上記駆動側、被駆動側各突出部２１、２４の円周方向側面同士は互いに平行になる。そして、これら駆動側、被駆動側各突出部２１、２４の円周方向側面に、上記各弾性部材２６ａ、２６ａの互いに反対側の２面を突き合わせている。 [Second Example of Embodiment]
FIGS. 5-8 has shown the 2nd example of embodiment of this invention corresponding to Claim 1, 4-6. The elastic shaft coupling 15a of this example is different from the first example described above in the structure of the elastic member 26a. The structure of both the drive side and driven side transmission members 18 and 19 is basically the same as in the first example. In the case of the elastic shaft joint 15a of this example, each of the transmission members 18 and 19 has a rectangular parallelepiped shape between the circumferential side surfaces of the drive side and driven side projections 21 and 24. The elastic members 26a and 26a are sandwiched. In the neutral state of the transmission members 18, 19 after assembling the members 18, 19, 26 a constituting the elastic shaft joint 15 a, the circumferential side surfaces of the drive side and driven side projections 21, 24 are Are parallel to each other. Then, the two opposite surfaces of the elastic members 26a and 26a are abutted against the circumferential side surfaces of the drive-side and driven-side protrusions 21 and 24, respectively.

上記各弾性部材２６ａ、２６ａはそれぞれ、芯材２７ａと被覆部２８ａとを組み合わせて成る。このうちの芯材２７ａは、比較的硬い弾性材製で、上記第一、第二両伝達部材１８、１９の軸方向に関する幅が、上記円周方向の中央部から同じく両端部に向かうに従って小さくなる。この為に本例の場合には、上記第一、第二両伝達部材１８、１９の径方向から見た、上記芯材２７ａの端面（断面）形状を、上記軸方向を短径とし、上記円周方向を長径とした、楕円形としている。又、上記被覆部２８ａは、この円周方向に関する幅が上記芯材２７ａよりも大きく、この芯材２７ａのうちで上記各突出部２１、２４の円周方向側面に対向する部分の全体を覆っている。更に本例の場合には、上記各弾性部材２６ａ、２６ａを円盤状の連結部３１の外周面に、放射状に設けている。この連結部３１の外径は、上記各突出部２１、２４の内接円の直径以下である。上記被覆部２８ａは、インサート成形により、この様な連結部３１及び上記各芯材２７ａ、２７ａのほぼ全体を（これら各芯材２７ａ、２７ａの先端部を除き）包埋している。 Each of the elastic members 26a and 26a is formed by combining a core material 27a and a covering portion 28a. Of these, the core material 27a is made of a relatively hard elastic material, and the width in the axial direction of the first and second transmission members 18 and 19 decreases from the center in the circumferential direction toward both ends. Become. For this reason, in the case of this example, the end face (cross-sectional) shape of the core material 27a viewed from the radial direction of the first and second transmission members 18, 19 has the short axis as the axial direction, It is an ellipse with the circumferential direction as the major axis. The covering portion 28a has a width in the circumferential direction larger than that of the core material 27a, and covers the entire portion of the core material 27a that faces the side surfaces in the circumferential direction of the protrusions 21 and 24. ing. Further, in the case of this example, the elastic members 26 a and 26 a are provided radially on the outer peripheral surface of the disk-like connecting portion 31. The outer diameter of the connecting portion 31 is equal to or smaller than the diameter of the inscribed circle of the projecting portions 21 and 24. The covering portion 28a embeds almost all of the connecting portion 31 and the core members 27a and 27a (except for the tip portions of the core members 27a and 27a) by insert molding.

この様な本例の構造の場合も、出力軸１２ａとウォーム軸６ａとの間（図１参照）でトルクを伝達する際には、上記各弾性部材２６ａ、２６ａが弾性変形しつつ、このトルクを伝達する。そして、これら各弾性部材２６ａ、２６ａを圧縮し始める際には、先ず、軟らかい上記被覆部２８ａを或る程度圧縮方向に弾性変形した後に、硬い上記芯材２７ａを圧縮方向に弾性変形し始める。この為、前述した実施の形態の第１例の場合と同様に、伝達すべきトルクが上昇、低下する過程でも、伝達されるトルクが急変動する事を防止できて、過渡特性を全体として良好にでき、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。 Also in the case of the structure of this example, when the torque is transmitted between the output shaft 12a and the worm shaft 6a (see FIG. 1), the elastic members 26a and 26a are elastically deformed and the torque is transmitted. To communicate. When starting to compress the elastic members 26a, 26a, first, the soft covering portion 28a is elastically deformed to some extent in the compression direction, and then the hard core material 27a is elastically deformed in the compression direction. For this reason, as in the case of the first example of the above-described embodiment, even when the torque to be transmitted rises and falls, it is possible to prevent the transmitted torque from suddenly changing, and the transient characteristics as a whole are good. It is possible to prevent the driver operating the steering wheel from feeling uncomfortable.

以上の説明は、本発明の弾性軸継手を、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の先端部とウォーム軸の基端部との間に装着した場合に就いて述べたが、本発明の弾性軸継手は、この様な部分に限らず、１対の回転軸同士の間でトルクを伝達する、各種機械装置に適用できる。 The above description has been given when the elastic shaft coupling of the present invention is mounted between the distal end portion of the output shaft of the electric motor constituting the electric power steering apparatus and the proximal end portion of the worm shaft. The elastic shaft coupling of the present invention is not limited to such a portion, and can be applied to various mechanical devices that transmit torque between a pair of rotating shafts.

本発明の実施の形態の第１例を示す、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の要部断面図。BRIEF DESCRIPTION OF THE DRAWINGS The principal part sectional drawing of the electrically driven power steering apparatus incorporating the elastic shaft coupling which shows the 1st example of embodiment of this invention. 弾性軸継手のみを取り出して示す分解斜視図。The exploded perspective view which takes out and shows only an elastic shaft coupling. 組み立ててから図２のイ−イ線で切断した状態で示す斜視図。The perspective view shown in the state cut | disconnected by the II line | wire of FIG. 第二の弾性材の厚さが互いに異なる、弾性部材の２例を示す、部分切断斜視図。The partial cut perspective view which shows two examples of the elastic member from which the thickness of a 2nd elastic material differs mutually. 本発明の実施の形態の第２例を示す、図２と同様の図。The figure similar to FIG. 2 which shows the 2nd example of embodiment of this invention. 組み立ててから図５のロ−ロ線で切断した状態で示す斜視図。The perspective view shown in the state cut | disconnected by the roll line of FIG. 弾性部材を取り出して示す斜視図。The perspective view which takes out and shows an elastic member. この弾性材のうちの芯材のみを示す斜視図。The perspective view which shows only the core material among this elastic material. 自動車用操舵装置の１例を示す部分縦断側面図。The partial longitudinal section side view showing an example of the steering device for cars. 従来構造の１例を示す、図９の拡大ハ−ハ断面図。FIG. 10 is an enlarged cross-sectional view of an example of a conventional structure in FIG. 9.

符号の説明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、６ａウォーム軸
７電動モータ
８ウォーム
９ａ、９ｂ転がり軸受
１０押圧駒
１１コイルばね
１２、１２ａ出力軸
１３スプライン孔
１４スプライン軸部
１５、１５ａ弾性軸継手
１６駆動側セレーション部
１７被駆動側セレーション部
１８駆動側伝達部材
１９被駆動側伝達部材
２０駆動側基板部
２１駆動側突出部
２２駆動側セレーション孔
２３被駆動側基板部
２４被駆動側突出部
２５被駆動側セレーション孔
２６、２６ａ弾性部材
２７、２７ａ芯材
２８、２８ａ被覆部
２９連結環
３０連結腕部
３１連結部 DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Steering shaft 3 Housing 4 Worm wheel 5 Worm tooth | gear 6, 6a Worm shaft 7 Electric motor 8 Worm 9a, 9b Rolling bearing 10 Pressing piece 11 Coil spring 12, 12a Output shaft 13 Spline hole 14 Spline shaft part 15, 15a Elastic shaft coupling 16 Drive side serration part 17 Driven side serration part 18 Drive side transmission member 19 Driven side transmission member 20 Drive side substrate part 21 Drive side protrusion part 22 Drive side serration hole 23 Drive side substrate part 24 Drive side Protrusion 25 Driven side serration hole 26, 26a Elastic member 27, 27a Core 28, 28a Cover 29 Connection ring 30 Connection arm 31 Connection

Claims

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、このトルクの方向に関して弾性変形可能な弾性部材を介して伝達する為、上記両回転軸のうちの一方の回転軸の端部に、この一方の回転軸と同心に支持される、これら両回転軸のうちの他方の回転軸に対向する面に、回転方向に関して間欠的に、それぞれこの他方の回転軸に向け軸方向に突出する複数の第一突出部を備えた第一伝達部材と、この他方の回転軸の端部に、この他方の回転軸と同心に支持される、上記一方の回転軸に対向する面に、回転方向に関して間欠的に、それぞれこの一方の回転軸に向け軸方向に突出する複数の第二突出部を備えた第二伝達部材と、これら各第二突出部の円周方向側面と上記各第一突出部の円周方向側面との間に挟持された、弾性部材とを備えた弾性軸継手に於いて、この弾性部材は、第一の弾性材製の芯材を、この第一の弾性材よりも軟らかい第二の弾性材製の被覆部で覆い、このうちの被覆部と、上記第一、第二各突出部の円周方向側面とを当接させている事を特徴とする弾性軸継手。 In order to transmit torque between ends of a pair of rotating shafts arranged in series with respect to the axial direction via an elastic member that can be elastically deformed with respect to the direction of the torque, one of the rotating shafts The other rotating shaft is intermittently provided with respect to the rotation direction on the surface of the rotating shaft that is concentrically supported by the one rotating shaft and facing the other rotating shaft. A first transmission member provided with a plurality of first protrusions projecting in the axial direction toward the first rotation shaft, and the one rotation shaft supported concentrically with the other rotation shaft at the end of the other rotation shaft. A second transmission member having a plurality of second protrusions protruding in the axial direction toward the one rotation axis intermittently with respect to the rotation direction on the opposing surface, and the circumferential direction of each of these second protrusions Sandwiched between the side surface and the circumferential side surface of each of the first protrusions. In the elastic shaft coupling provided with the elastic member, the elastic member covers the core material made of the first elastic material with the covering portion made of the second elastic material which is softer than the first elastic material. The elastic shaft coupling is characterized in that the covering portion of these and the circumferential side surfaces of the first and second protrusions are in contact with each other.

第一、第二各突出部の円周方向側面同士の間に、それぞれが円柱状の弾性部材を、これら各弾性部材の軸方向端面をこれら各突出部の円周方向側面に突き合わせた状態で挟持しており、これら各弾性部材は、軸方向中央部から両端部に向かうに従って外径が小さくなる方向に傾斜した芯材と、この芯材よりも大きな軸方向寸法を有し、この芯材全体を覆った被覆部とから成るものである、請求項１に記載した弾性軸継手。 Between the circumferential side surfaces of the first and second projecting portions, each is a cylindrical elastic member, and the axial end surfaces of these elastic members are butted against the circumferential side surfaces of the projecting portions. Each of these elastic members has a core material that is inclined in a direction in which the outer diameter decreases from the central portion in the axial direction toward both ends, and has a larger axial dimension than the core material. The elastic shaft coupling according to claim 1, comprising a covering portion covering the whole.

第一、第二各突出部の円周方向側面同士の間に存在する、複数の弾性部材を設置すべき空間に合わせて配置した、これら各弾性部材の周囲に、上記各突出部の外接円の直径以上の内径を有する連結環が設けられており、連結腕部によりこの連結環と上記各弾性部材とを連結している、請求項２に記載した弾性軸継手。 A plurality of elastic members existing between the circumferential side surfaces of the first and second projecting portions are arranged in accordance with a space in which the projecting portions are to be installed. The elastic shaft coupling according to claim 2, wherein a connecting ring having an inner diameter equal to or larger than the diameter of the elastic ring joint is provided, and the connecting ring connects the connecting ring and the elastic members.

第一、第二各突出部の円周方向側面同士の間に、それぞれが直方体状の弾性部材を、この円周方向に関するこれら各弾性部材の互いに反対側の２面を、上記各突出部の円周方向側面に突き合わせた状態で挟持しており、上記各弾性部材は、第一、第二両伝達部材の軸方向に関する幅が、上記円周方向の中央部から同じく両端部に向かうに従って小さくなる芯材と、この円周方向に関する幅が上記芯材よりも大きく、この芯材のうちで上記各突出部の円周方向側面に対向する部分を覆った被覆部とから成るものである、請求項１に記載した弾性軸継手。 Between the circumferential side surfaces of each of the first and second protrusions, each is a rectangular parallelepiped elastic member, and the two opposite surfaces of each elastic member in the circumferential direction are connected to each of the protrusions. Each elastic member has a width in the axial direction of both the first and second transmission members that decreases from the center in the circumferential direction toward both ends. The core material and the width in the circumferential direction is larger than that of the core material, and the covering material covers a portion of the core material that faces the circumferential side surface of each protrusion. The elastic shaft coupling according to claim 1.

第一、第二両伝達部材の径方向に関して、第一、第二各突出部の円周方向側面同士の間に存在する、複数の弾性部材を設置すべき空間に合わせて配置したこれら各弾性部材の内側に、外径が上記各突出部の内接円の直径以下である連結部が設けられており、上記径方向に関して上記各弾性部材の内端部がこの連結部の外周面に連結されて、放射状に配列されている、請求項４に記載した弾性軸継手。 With respect to the radial direction of both the first and second transmission members, each of these elasticities arranged between the circumferential side surfaces of the first and second projecting portions and arranged in accordance with the space in which a plurality of elastic members are to be installed. A connecting portion whose outer diameter is equal to or smaller than the diameter of the inscribed circle of each of the protruding portions is provided inside the member, and the inner end portion of each elastic member is connected to the outer peripheral surface of the connecting portion with respect to the radial direction. The elastic shaft coupling according to claim 4, wherein the elastic shaft couplings are arranged radially.

固定の部分に支持されて回転する事のないハウジングと、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回転軸と、上記ハウジングの内部でこの回転軸の一部に、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ウォームホイールと、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されたウォームと、このウォームを回転駆動する為の電動モータと、この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、これら両軸同士の間でトルクを伝達する継手装置とを備えた電動式パワーステアリング装置に於いて、この継手装置が、請求項１〜５のうちの何れか１項に記載された弾性軸継手である事を特徴とする電動式パワーステアリング装置。 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 5.