JP5035264B2

JP5035264B2 - Universal joint

Info

Publication number: JP5035264B2
Application number: JP2009027756A
Authority: JP
Inventors: 篤志前田
Original assignee: NSK Ltd
Current assignee: NSK Ltd
Priority date: 2009-02-09
Filing date: 2009-02-09
Publication date: 2012-09-26
Anticipated expiration: 2029-02-09
Also published as: JP2010181015A

Description

この発明は、例えばステアリングシャフトの動きをステアリングギヤに伝達する為、自動車のステアリング装置に組み込んだ状態で使用する自在継手の改良に関する。具体的には、防食等の為に表面を塗装した構造に関して、塗膜の端部に存在する微小段差に基づくシール性低下を防止するものである。 The present invention relates to an improvement in a universal joint used in a state where it is incorporated in a steering device of an automobile, for example, to transmit the movement of a steering shaft to a steering gear. Specifically, with respect to the structure in which the surface is coated for corrosion prevention or the like, the sealing performance is prevented from being deteriorated due to a minute step existing at the end of the coating film.

自動車のステアリング装置は、例えば特許文献１〜２に記載されている如く、図８に示す様に構成している。運転者が操作するステアリングホイール１の動きは、ステアリングシャフト２、自在継手３、中間シャフト４、別の自在継手３を介して、ステアリングギヤユニット５の入力軸６に伝達される。そして、このステアリングギヤユニット５に内蔵したラック＆ピニオン機構により左右１対のタイロッド７、７を押し引きし、左右１対の操舵輪（一般的には前輪）に、上記ステアリングホイール１の操作量に応じて、適切な舵角を付与する様に構成している。 The steering apparatus for an automobile is configured as shown in FIG. 8 as described in, for example, Patent Documents 1 and 2. The movement of the steering wheel 1 operated by the driver is transmitted to the input shaft 6 of the steering gear unit 5 through the steering shaft 2, the universal joint 3, the intermediate shaft 4, and another universal joint 3. A pair of left and right tie rods 7 and 7 are pushed and pulled by a rack and pinion mechanism built in the steering gear unit 5, and the operation amount of the steering wheel 1 is applied to a pair of left and right steering wheels (generally, front wheels). Depending on the situation, an appropriate rudder angle is provided.

この様なステアリング装置に組み込む自在継手として一般的には、カルダン継手と呼ばれる十字軸継手が、広く使用されている。図９〜１０は、上記特許文献１〜２に記載される等により、従来から広く知られている自在継手の１例を示している。尚、図９〜１０に示した構造は、振動の伝達を防止する、所謂防振継手であるが、本発明の対象となる自在継手は、必ずしも防振構造を具備する必要はない。そこで、以下の説明は防振構造を省略して、自在継手３の本体部分の構造に就いて説明する。 In general, a cross joint called a cardan joint is widely used as a universal joint incorporated in such a steering apparatus. 9 to 10 show an example of a universal joint that has been widely known so far, as described in Patent Documents 1 and 2 above. The structures shown in FIGS. 9 to 10 are so-called vibration-proof joints that prevent transmission of vibration. However, the universal joint that is the subject of the present invention does not necessarily have to have a vibration-proof structure. Therefore, in the following description, the structure of the main body portion of the universal joint 3 will be described with the vibration-proof structure omitted.

この自在継手３は、十分な剛性を有する金属材によりそれぞれが二股状に形成された１対のヨーク８ａ、８ｂと、軸受鋼の如き合金鋼等の硬質金属により造られた十字軸９とから構成される。これら各ヨーク８ａ、８ｂの両端部には、互いに同心の円孔１０、１０を形成している。そしてこれら各円孔１０、１０に、やはり軸受鋼、肌焼鋼等の硬質金属製の板材により有底円筒状に造られた軸受カップ１１、１１を、互いの開口を対向させた状態で内嵌固定している。又、上記十字軸９は、１対の柱部の中間部同士を互いに直交させた如き形状を有し、それぞれが円柱状である、４個所の軸部１２、１２を有する。即ち、中心部に設けた結合基部１３の円周方向等間隔４箇所位置に、それぞれ上記各軸部１２、１２の基端部を結合固定している。これら各軸部１２、１２の中心軸は、同一平面上に存在する。 The universal joint 3 includes a pair of yokes 8a and 8b each formed in a bifurcated shape by a metal material having sufficient rigidity, and a cross shaft 9 made of a hard metal such as an alloy steel such as bearing steel. Composed. Concentric holes 10 and 10 are formed at both ends of each of the yokes 8a and 8b. And in these circular holes 10 and 10, bearing cups 11 and 11 made of a hard metal plate material such as bearing steel and case-hardened steel are formed in a state where the openings face each other. It is fitted and fixed. The cross shaft 9 has a shape such that the middle portions of the pair of column portions are orthogonal to each other, and has four shaft portions 12 and 12 each having a cylindrical shape. In other words, the base end portions of the shaft portions 12 and 12 are fixedly coupled to four positions at equal intervals in the circumferential direction of the coupling base portion 13 provided in the center portion. The central axes of these shaft portions 12 and 12 exist on the same plane.

この様な各軸部１２、１２の軸方向中間部乃至先端部は、上記各軸受カップ１１、１１内に挿入している。そして、これら各軸受カップ１１、１１の内周面と上記各軸部１２、１２の先半部外周面との間に、ニードル軸受等のラジアル軸受１４、１４を設け、上記十字軸９に対して上記各ヨーク８ａ、８ｂが、軽い力で揺動変位する様にしている。この様に構成する為、これら両ヨーク８ａ、８ｂの中心軸同士が一致しない状態でも、これら両ヨーク８ａ、８ｂの間で回転力の伝達を、伝達ロスを僅少に抑えた状態で行える。 The axial direction intermediate part thru | or the front-end | tip part of each such shaft part 12 and 12 are inserted in each said bearing cup 11 and 11. Further, radial bearings 14, 14 such as needle bearings are provided between the inner peripheral surfaces of the bearing cups 11, 11 and the front half outer peripheral surfaces of the shaft portions 12, 12. The yokes 8a and 8b are oscillated and displaced with a light force. Due to such a configuration, even when the central axes of the yokes 8a and 8b do not coincide with each other, the rotational force can be transmitted between the yokes 8a and 8b with little transmission loss.

上述の様な自在継手３、３のうち、車室外に設置する（図８で下側の）自在継手３の場合には、上記十字軸９を構成する上記各軸部１２、１２の基端部（上記結合基部１３側の端部）と上記各軸受カップ１１、１１の開口部との間に、それぞれシールリング１５、１５を設けている。そして、これら各シールリング１５、１５により、上記各ラジアル軸受１４、１４の設置部分に泥水等が進入するのを防止し、上記自在継手３の耐久性の確保を図っている。上記各シールリング１５、１５はそれぞれ、芯金１６により弾性材１７を補強して成る。このうちの芯金１６は、軟鋼板等の金属板により、断面Ｌ字形で全体を円環状に形成している。又、上記弾性材１７は、ゴムの如きエラストマー製で、上記芯金１６を全周に亙り覆っており、ラジアルシールリップ１８とスラストシールリップ１９との、１対のシールリップ１８、１９を有する。 Of the universal joints 3 and 3 as described above, in the case of the universal joint 3 installed on the outside of the passenger compartment (lower side in FIG. 8), the base ends of the shaft portions 12 and 12 constituting the cross shaft 9. Seal rings 15 and 15 are provided between the portion (the end portion on the coupling base 13 side) and the opening of each of the bearing cups 11 and 11, respectively. The seal rings 15 and 15 prevent muddy water and the like from entering the installed portions of the radial bearings 14 and 14, thereby ensuring the durability of the universal joint 3. Each of the seal rings 15, 15 is formed by reinforcing an elastic material 17 with a cored bar 16. Of these, the metal core 16 is formed in an annular shape with an L-shaped cross section by a metal plate such as a mild steel plate. The elastic member 17 is made of an elastomer such as rubber, covers the core 16 over the entire circumference, and has a pair of seal lips 18 and 19 including a radial seal lip 18 and a thrust seal lip 19. .

それぞれがこの様な構成を有する、上記各シールリング１５、１５は、上記芯金１６を包埋した基部を上記各軸部１２、１２の基端部に締り嵌めで（弾性材１７の一部を弾性変形させた状態で）外嵌する事により、これら各軸部１２、１２の基端部に、嵌合部のシール性を確保した状態で支持している。この様にこれら各軸部１２、１２の基端部に上記各シールリング１５、１５を支持し、上記十字軸９と上記各軸受カップ１１、１１とを組み合わせた状態で、上記各シールリップ１８、１９のうちのラジアルシールリップ１８のシール縁は、上記各軸受カップ１１、１１の外周面のうちで開口寄り端部に、全周に亙り弾性的に当接する。又、上記スラストシールリップ１９のシール縁は、上記各軸受カップ１１、１１の開口部に形成された内向鍔部２０の外面（上記結合基部１３に対向する面）に、全周に亙り弾性的に当接する。 Each of the seal rings 15 and 15 having such a structure is formed by tightening a base portion embedded with the core metal 16 on a base end portion of each of the shaft portions 12 and 12 (part of the elastic material 17). By being externally fitted (in a state of being elastically deformed), the base end portions of the shaft portions 12 and 12 are supported in a state in which the sealing performance of the fitting portions is ensured. In this manner, the seal rings 15 and 15 are supported on the base end portions of the shaft portions 12 and 12, and the seal lips 18 are combined with the cross shaft 9 and the bearing cups 11 and 11. 19, the seal edge of the radial seal lip 18 is elastically abutted over the entire periphery of the outer peripheral surface of each of the bearing cups 11 and 11 toward the end near the opening. Further, the seal edge of the thrust seal lip 19 is elastic over the entire circumference on the outer surface of the inward flange portion 20 formed in the opening of each of the bearing cups 11 and 11 (the surface facing the coupling base portion 13). Abut.

更に、上記各軸部１２、１２中心部にはそれぞれ有底の挿入孔２１、２１を、これら各軸部１２、１２の先端面に開口する状態で、上記各軸部１２、１２の軸方向に形成している。そして、これら各挿入孔２１、２１の内側に、合成樹脂製のピン２２、２２を挿入している。これら各ピン２２、２２は、上記各軸受カップ１１、１１と上記各軸部１２、１２との間で突っ張る事により、これら各軸受カップ１１、１１の開口端部と前記基部１３との距離が縮まり過ぎる事を防止する。そして、前記各シーリング１５、１５のスラストシールリップ１９が過度に圧縮されたり、反対に圧縮量が低下し過ぎる事を防止する。即ち、自在継手３の使用時に前記十字軸９と上記各軸受カップ１１、１１との間に加わるスラスト荷重に基づき、スラスト荷重作用側（アンカ側）のシールリング１５が過度に圧縮されて耐久性が損なわれ、反対側（反アンカ側）のシールリング１５の圧縮量が低下し過ぎて、このシールリング１５によるシール性が損なわれる事を防止する。上記各ピン２２、２２は、軸方向に弾性変形しつつ、上述の様なスラスト荷重を支承する。そして、この弾性変形に伴う軸方向寸法の変化分、自在継手３の構成部材８ａ、８ｂ、９、１１、１５の寸法精度及び組立精度を特に高くしなくても、上記各シールリング１５、１５の圧縮量を適性範囲に保持できる。 Furthermore, the axial direction of each said shaft part 12 and 12 in the state which opened the bottomed insertion hole 21 and 21 in the center part of each said shaft part 12 and 12 at the front end surface of these each shaft part 12 and 12, respectively. Is formed. Then, synthetic resin pins 22 and 22 are inserted inside these insertion holes 21 and 21, respectively. The pins 22 and 22 are stretched between the bearing cups 11 and 11 and the shafts 12 and 12, so that the distance between the opening end of the bearing cups 11 and 11 and the base 13 is increased. Preventing it from shrinking too much. Then, the thrust seal lip 19 of each of the seals 15 and 15 is prevented from being excessively compressed, and conversely, the amount of compression is not excessively reduced. That is, when the universal joint 3 is used, the thrust load acting side (anchor side) seal ring 15 is excessively compressed on the basis of the thrust load applied between the cross shaft 9 and the bearing cups 11, 11. Is prevented, and the amount of compression of the seal ring 15 on the opposite side (anti-anchor side) is excessively reduced, thereby preventing the sealing performance of the seal ring 15 from being impaired. Each of the pins 22 and 22 supports the thrust load as described above while elastically deforming in the axial direction. The above-described seal rings 15 and 15 can be obtained without particularly increasing the dimensional accuracy and assembly accuracy of the constituent members 8a, 8b, 9, 11, and 15 of the universal joint 3 due to the change in the axial dimension due to the elastic deformation. The amount of compression can be kept within the proper range.

但し、上述の様なピン２２、２２を設けない、十字軸式の自在継手に就いても、例えば特許文献３〜４に記載される等により、従来から広く知られている。図１１は、このうちの特許文献４に記載された、自在継手の構造を示している。この従来構造の第２例の場合、軸受カップ１１ａの底部２３の内面中央寄り部分に突条２４、２４を形成し、これら各突条２４、２４の先端縁を、十字軸を構成する軸部１２の先端面に当接させている。この様な構造によっても、自在継手の構成部材の寸法精度及び組立精度を確保さえすれば、上記軸受カップ１１ａと上記軸部１２との間に設けるシールリングの圧縮量を適性範囲に保持できる。 However, a cross shaft type universal joint that does not have the pins 22 and 22 as described above has been widely known, for example, as described in Patent Documents 3 to 4. FIG. 11 shows the structure of a universal joint described in Patent Document 4 among them. In the case of this second example of the conventional structure, the ridges 24, 24 are formed on the portion near the center of the inner surface of the bottom 23 of the bearing cup 11a, and the tip edges of these ridges 24, 24 are the shaft portions constituting the cross shaft. It is made to contact | abut to the 12 front end surface. Even with such a structure, the compression amount of the seal ring provided between the bearing cup 11a and the shaft portion 12 can be maintained within an appropriate range as long as the dimensional accuracy and assembly accuracy of the components of the universal joint are ensured.

何れの構造の場合でも、ステアリング装置を構成する自在継手３には、防錆の為の塗装を施す。特に、前述の図８に示したステアリング装置で、中間シャフト４と入力軸６とを結合する、前下側の自在継手３は、車室外（エンジンルーム内）に設けられて、雨水や泥水が付着し易い為、塗装を施す必要性が高い。そして、この塗装は、この自在継手３の完成状態（構成各部材８ａ、８ｂ、９、１１、１５を組み立てた状態）で行う。この理由は、塗装作業の簡略化の為、軸受カップ１１の内面等の塗装不要部分に塗料が付着するのを防止する為、更には、組立作業前に塗装を行うと、組立作業に伴って塗膜が削り取られる為等である。又、塗装は、電着塗装の如く、塗料の微小粒を表面に付着させる方法により行う。従って、図１２に示す様に塗膜２５は、組立状態で表面に露出している部分にのみ形成される。この為、例えば軸受カップ１１の開口端部でラジアルシールリップ１８により覆われた部分は塗膜により覆われず、金属が露出したままとなる。そして、自在継手３を組み立てたままの状態でラジアルシールリップ１８のシール縁が当接している部分に、上記塗膜２５の厚さ分だけの段差２８が生じる。 In any structure, the universal joint 3 constituting the steering device is coated for rust prevention. In particular, in the steering device shown in FIG. 8 described above, the front lower universal joint 3 that connects the intermediate shaft 4 and the input shaft 6 is provided outside the vehicle compartment (inside the engine room), and rainwater and muddy water are received. Because it is easy to adhere, the need to paint is high. This painting is performed in a completed state of the universal joint 3 (a state in which the constituent members 8a, 8b, 9, 11, and 15 are assembled). This is because, in order to simplify the painting work, in order to prevent the paint from adhering to the unnecessary parts such as the inner surface of the bearing cup 11, and further, if painting is performed before the assembling work, This is because the coating film is scraped off. The coating is performed by a method in which fine particles of paint are adhered to the surface as in electrodeposition coating. Therefore, as shown in FIG. 12, the coating film 25 is formed only on a portion exposed to the surface in the assembled state. For this reason, for example, the portion covered with the radial seal lip 18 at the opening end of the bearing cup 11 is not covered with the coating film, and the metal remains exposed. Then, a step 28 corresponding to the thickness of the coating film 25 is produced at the portion where the seal edge of the radial seal lip 18 is in contact with the universal joint 3 as assembled.

一方、自在継手の運転時に、上記ラジアルシールリップ１８のシール縁は上記軸受カップ１１の外周面に対して、円周方向に変位するだけでなく、軸方向にも変位する。即ち、１対のヨーク８ａ、８ｂ同士の間にジョイント角が存在する状態で、これら両ヨーク８ａ、８ｂ同士の間でトルクを伝達すると、前記各軸受カップ１１の内側で前記各軸部１２が捩り方向に揺動変位する。この揺動変位に伴って、上記ラジアルシールリップ１８のシール縁が上記軸受カップ１１の外周面に対し、円周方向に変位する。同時に、前記十字軸９と上記各軸受カップ１１との間に、スラスト荷重が加わる。そして、このスラスト荷重に基づく構成各部材の弾性変形分、上記ラジアルシールリップ１８のシール縁が上記軸受カップ１１の外周面に対して、軸方向に変位する。この軸方向の変位は、前記図１０に示す様なピン２２、２２を設けた構造の場合に著しくなるが、図１１に示す様な構造の場合にも、軸受カップ１１ａの底部２３等の弾性変形に伴って発生する。そして、何れの場合でも、上記軸方向の変位に伴って上記ラジアルシールリップ１８のシール縁が、上記塗膜２５の端縁部に存在する段差２８を乗り越えつつ移動する。この結果、このシール縁と上記軸受カップ１１の外周面との当接部の当接状態が不安定になり、この当接部のシール性が悪化する可能性がある。 On the other hand, during the operation of the universal joint, the seal edge of the radial seal lip 18 is displaced not only in the circumferential direction but also in the axial direction with respect to the outer peripheral surface of the bearing cup 11. That is, when torque is transmitted between the yokes 8a and 8b in a state where there is a joint angle between the pair of yokes 8a and 8b, the shaft portions 12 are moved inside the bearing cups 11. Swing displacement in the torsional direction. With this swinging displacement, the seal edge of the radial seal lip 18 is displaced in the circumferential direction with respect to the outer peripheral surface of the bearing cup 11. At the same time, a thrust load is applied between the cross shaft 9 and the bearing cups 11. Then, the elastic deformation of each constituent member based on this thrust load causes the seal edge of the radial seal lip 18 to be displaced in the axial direction with respect to the outer peripheral surface of the bearing cup 11. This axial displacement becomes significant in the case of the structure provided with the pins 22 and 22 as shown in FIG. 10, but also in the case of the structure as shown in FIG. 11, the elasticity of the bottom 23 and the like of the bearing cup 11a. Occurs with deformation. In any case, along with the displacement in the axial direction, the seal edge of the radial seal lip 18 moves over the step 28 existing at the edge of the coating film 25. As a result, the contact state of the contact portion between the seal edge and the outer peripheral surface of the bearing cup 11 becomes unstable, and the sealing performance of the contact portion may deteriorate.

特許文献５には、ラジアルシールリップの周囲にカバー部を設け、このラジアルシールリップに塗料が付着する事を防止する構造が記載されている。この様な特許文献５に記載された構造は、上記ラジアルシールリップの弾性が塗料付着により低下する事を防止する為のもので、上述の様なシール性低下に結び付く塗膜２５の段差２８の発生を防止できるものではない。又、特許文献６には、スラストシールリップの先端部に環状溝を形成する事により、このスラストシールリップのシール縁と軸受カップの内向鍔部との当接状態を改善する構造が記載されているが、塗膜２５の段差２８に基づくシール性低下を防止できるものではない。 Patent Document 5 describes a structure in which a cover is provided around the radial seal lip to prevent the paint from adhering to the radial seal lip. Such a structure described in Patent Document 5 is intended to prevent the elasticity of the radial seal lip from being lowered due to adhesion of the paint, and the step 28 of the coating film 25 that leads to a decrease in the sealing performance as described above. It cannot prevent the occurrence. Patent Document 6 describes a structure that improves the contact state between the seal edge of the thrust seal lip and the inward flange of the bearing cup by forming an annular groove at the tip of the thrust seal lip. However, it is not possible to prevent a decrease in sealing performance based on the step 28 of the coating film 25.

特開平８−１３５６７４号公報Japanese Patent Application Laid-Open No. 8-135684 特開平９−６０６５０号公報Japanese Patent Laid-Open No. 9-60650 特開平６−２８０８９０号公報JP-A-6-280890 特開平７−２０８４９２号公報JP 7-208492 A 特開平７−２１７６６８号公報JP-A-7-217668 特開２００６−２９５５１号公報JP 2006-29551 A

本発明は、上述の様な事情に鑑みて、塗膜の端部に存在する微小段差に基づくシール性低下を防止できる構造を実現すべく発明したものである。 In view of the above-described circumstances, the present invention was invented to realize a structure capable of preventing a deterioration in sealing performance based on a minute step present at an end of a coating film.

本発明の自在継手は、前述した従来から知られている自在継手と同様に、１対のヨークと、４個の円孔と、４個の軸受カップと、十字軸と、４組のラジアル軸受と、４個のシールリングとを備える。
このうちの１対のヨークは、それぞれが二股状に形成されている。
又、上記各円孔は、上記両ヨークの両端部に互いに同心に形成されている。
又、上記各軸受カップは、それぞれが有底円筒状であって、互いの開口を対向させた状態で、上記各円孔の内側に内嵌固定されている。
又、上記十字軸は、結合基部の外周面に４本の軸部を放射状に固設して成り、これら各軸部を上記各軸受カップ内に挿入した状態で、上記両ヨークと組み合わされている。
又、上記各ラジアル軸受は、上記各軸受カップの内周面と上記各軸部の外周面との間に設けられている。
又、上記各シールリングは、上記各軸部の基端部にそれぞれの基部を外嵌支持された状態で、これら各軸部の基端部と上記各軸受カップの開口部との間に設けられている。
そして、上記各シールリングは、これら各軸受カップの外周面のうちで開口寄り端部に全周に亙り当接するシールリップを設けたものであり、これら各シールリップのシール縁を上記各軸受カップの外周面に当接させた状態で表面を塗装されている。 The universal joint of the present invention is a pair of yokes, four circular holes, four bearing cups, a cross shaft, and four sets of radial bearings, similar to the previously known universal joints. And four seal rings.
Each of the pair of yokes is formed in a bifurcated shape.
The circular holes are concentrically formed at both ends of the yokes.
Each of the bearing cups has a bottomed cylindrical shape, and is fitted and fixed inside the circular holes with the openings facing each other.
Further, the cross shaft is formed by radially fixing four shaft portions on the outer peripheral surface of the coupling base portion, and these shaft portions are inserted into the bearing cups and combined with the yokes. Yes.
Each radial bearing is provided between the inner peripheral surface of each bearing cup and the outer peripheral surface of each shaft portion.
The seal rings are provided between the base end portions of the shaft portions and the opening portions of the bearing cups, with the base portions fitted and supported on the base end portions of the shaft portions. It has been.
Each of the seal rings is provided with a seal lip that is in contact with the entire periphery of the outer peripheral surface of each of the bearing cups at the end closer to the opening. The surface is painted in a state where it is brought into contact with the outer peripheral surface.

特に、本発明の自在継手に於いては、上記各シールリップを、先端部が二股に形成されて、軸方向に離隔した１対のシール縁を有するものとしている。
又、本発明の場合には、上記各シールリップの先端部に設けられた１対のシール縁同士の軸方向の間隔を、使用時に於ける上記各軸部と上記各軸受カップとの、これら各軸受カップ内へのこれら各軸部の挿入量が増大する方向に関する、中立位置からの軸方向変位量以上とする。
この様な本発明を実施する場合に好ましくは、請求項２に記載した発明の様に、上記各シールリップの先端部に設けられた１対のシール縁同士の軸方向の間隔を、中立状態で、上記各軸部の先端面と上記各軸受カップの底部内面との間に存在する隙間の最小厚さ以上とする。
尚、本発明は、請求項３に記載した発明の様に、上記各軸部の端面に開口する状態でこれら各軸部の内側に有底の挿入孔を、軸方向に亙って形成し、これら各挿入孔に挿入されてそれぞれの一端をこの挿入孔の奥端に突き当てられた合成樹脂製のピンの他端を、上記各軸受カップの底部内面に突き当てた構造で実施する事が、発明の効果を顕著に得られる。この様な構造は、上記各軸部の、軸方向変位量が多くなる為である。 In particular, in the universal joint of the present invention, each of the seal lips has a pair of seal edges that are bifurcated at the tip and separated in the axial direction.
In the case of the present invention, the axial distance between a pair of seal edges provided at the tip of each seal lip is determined by the distance between the shaft and the bearing cup in use. The amount of displacement in the axial direction from the neutral position in the direction in which the amount of insertion of each shaft portion into each bearing cup is increased.
In the case of carrying out the present invention as described above, preferably, as in the invention described in claim 2, the axial interval between the pair of seal edges provided at the tip of each seal lip is set to the neutral state. Thus, the thickness is not less than the minimum thickness of the gap existing between the front end surface of each shaft portion and the bottom inner surface of each bearing cup.
In the present invention, as in the invention described in claim 3 , a bottomed insertion hole is formed in the axial direction inside each of the shaft portions so as to open to the end face of each of the shaft portions. The other end of the synthetic resin pin inserted into each insertion hole and having one end abutted against the inner end of the insertion hole is abutted against the bottom inner surface of each bearing cup. However, the effect of the invention can be remarkably obtained. Such a structure is because the amount of axial displacement of each shaft portion increases.

上述の様に構成する本発明の自在継手によれば、塗膜の端部に存在する微小段差に基づくシール性低下を防止できる。
即ち、本発明の自在継手の場合には、各軸受カップの外周面にそのシール縁を当接させるシールリップの先端部を二股にし、このシールリップの先端部に１対のシール縁を設けている為、上記各軸受カップと各シールリングとが軸方向に相対変位した場合でも、少なくとも一方のシール縁は段差部から外れた部分に存在する。この為、少なくとも一方のシール縁が相手面と、全周に亙って隙間のない状態で当接し、シール性を確保できる。 According to the universal joint of the present invention configured as described above, it is possible to prevent deterioration of the sealing performance based on a minute step existing at the end of the coating film.
That is, in the case of the universal joint of the present invention, the tip end of the seal lip that makes the seal edge contact the outer peripheral surface of each bearing cup is bifurcated, and a pair of seal edges is provided at the tip of the seal lip. Therefore, even when the bearing cups and the seal rings are displaced relative to each other in the axial direction, at least one seal edge is present at a portion deviated from the stepped portion. For this reason, at least one seal edge abuts on the mating surface with no gap over the entire circumference, and sealing performance can be ensured.

特に、本発明によれば、１対のシール縁のうちで上記各軸受カップの開口端寄りのシール縁が、塗膜の端部に存在する段差を乗り越えて移動する事がなくなる。この為、このシール縁によるシール性を、この段差の存在に関係なく、十分に確保できる。 In particular, according to the present invention , the seal edge near the opening end of each of the bearing cups out of the pair of seal edges does not move over the step existing at the end of the coating film. For this reason, the sealing performance by the seal edge can be sufficiently ensured regardless of the existence of the step.

［実施の形態の第１例］
図１〜２は、請求項１、３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、本例を含めて、本発明の特徴は、自在継手の運転時に発生する、十字軸９の軸部１２と、ヨークの円孔１０に内嵌した軸受カップ１１との軸方向変位に拘らず、これら軸部１２と軸受カップ１１との間のシール性を良好に保つ為の構造にある。その他の部分の構造及び作用は、前述の図９〜１０に示した従来構造の第１例、或は、前述の図１１に示した従来構造の第２例と同様であるから、重複する図示並びに説明は、省略若しくは簡略にし、以下、本発明の特徴部分を中心に説明する。 [First example of embodiment]
1 and 2 show a first example of an embodiment of the present invention corresponding to claims 1 and 3 . The feature of the present invention including this example is related to the axial displacement between the shaft portion 12 of the cross shaft 9 and the bearing cup 11 fitted in the circular hole 10 of the yoke, which occurs during the operation of the universal joint. The structure for maintaining a good sealing property between the shaft portion 12 and the bearing cup 11 is provided. The structure and operation of other parts are the same as those of the first example of the conventional structure shown in FIGS. 9 to 10 or the second example of the conventional structure shown in FIG. In addition, the description will be omitted or simplified, and the following description will focus on the features of the present invention.

上記軸部１２の基端部（図１〜２の下端部）と上記軸受カップ１１の開口側端部（図１〜２の下端部）との間に、芯金１６と弾性材１７ａとから成るシールリング１５ａを設けている。この弾性材１７ａは、ラジアルシールリップ１８ａとスラストシールリップ１９との、１対のシールリップ１８ａ、１９を有する。このうちのラジアルシールリップ１８ａは、先端部を二股に形成したもので、軸方向に離隔した１対のシール縁２６ａ、２６ｂを有する。即ち、上記ラジアルシールリップ１８ａの先端部の肉厚を、前述の図１２に示した従来構造のラジアルシールリップ１８の先端部の肉厚よりも大きくすると共に、上記ラジアルシールリップ１８ａの先端部に、内周面側に開口する凹溝２７を、全周に亙って形成している。そして、この凹溝２７の両側を、それぞれ上記両シール縁２６ａ、２６ｂとしている。これら両シール縁２６ａ、２６ｂは、軸方向に関してＬ₂₆（図２参照）だけ離隔している。一方、上記スラストシールリップ１９は、前述した従来構造と同様のもので、そのシール縁を上記軸受カップ１１に形成した内向鍔部２０の外面に、全周に亙って当接させている。 Between the base end portion (the lower end portion in FIGS. 1 and 2) of the shaft portion 12 and the opening side end portion (the lower end portion in FIGS. 1 and 2) of the bearing cup 11, from the core metal 16 and the elastic material 17a. A seal ring 15a is provided. The elastic member 17 a has a pair of seal lips 18 a and 19 including a radial seal lip 18 a and a thrust seal lip 19. Of these, the radial seal lip 18a is formed with a bifurcated tip, and has a pair of seal edges 26a and 26b spaced apart in the axial direction. That is, the thickness of the tip of the radial seal lip 18a is made larger than the thickness of the tip of the radial seal lip 18 having the conventional structure shown in FIG. A concave groove 27 that opens to the inner peripheral surface side is formed over the entire circumference. The both sides of the concave groove 27 are the seal edges 26a and 26b, respectively. These seal edges 26a, 26b are separated by L ₂₆ (see FIG. 2) in the axial direction. On the other hand, the thrust seal lip 19 is the same as the conventional structure described above, and its seal edge is in contact with the outer surface of the inward flange portion 20 formed on the bearing cup 11 over the entire circumference.

この軸受カップ１１の外周面を含めて、上記シールリング１５ａの弾性材１７ａにより覆われている部分を除く部分には、前述の図１２に示した従来構造の場合と同様に、防錆の為の塗装に基づく塗膜２５が形成されている。従って、上記軸受カップ１１の外周面の開口端部寄り部分で、上記ラジアルシールリップ１８ａの先端側（図１〜２の上側）のシール縁２６ａが当接している部分に、上記塗膜２５の厚さ分だけの段差２８（図２参照、図１には省略）が存在している。本例の場合には、自在継手の運転時に発生する、十字軸９の軸部１２と、ヨークの円孔１０に内嵌した軸受カップ１１との軸方向変位に拘らず、上記ラジアルシールリップ１８ａの基端側（図１〜２の下側）のシール縁２６ｂが、上記段差２８を跨いで移動しない様にしている。言い換えれば、この基端側のシール縁２６ｂは、上記軸受カップ１１の外周面の開口端寄り部分で、上記塗膜２５により覆われていない部分にのみ当接（摺接）する様にしている。尚、この塗膜２５を形成する為の塗装作業は、自在継手の構成各部材を組み立てた後、外力が加わらない（トルク伝達を行わない）、中立状態で行う。この中立状態で、上記自在継手を構成する、それぞれ４個ずつの、軸受カップ１１、シールリング１５ａ、ピン２２は、互いにほぼ同じ量だけ、弾性変形している。 The portion including the outer peripheral surface of the bearing cup 11 excluding the portion covered with the elastic material 17a of the seal ring 15a is for rust prevention as in the conventional structure shown in FIG. A coating film 25 based on this coating is formed. Therefore, the coating film 25 is in contact with the portion of the outer peripheral surface of the bearing cup 11 that is close to the opening end and the seal edge 26a on the tip side of the radial seal lip 18a (upper side in FIGS. There is a step 28 (see FIG. 2, omitted in FIG. 1) corresponding to the thickness. In the case of this example, the radial seal lip 18a is generated regardless of the axial displacement between the shaft portion 12 of the cross shaft 9 and the bearing cup 11 fitted in the circular hole 10 of the yoke, which occurs during the operation of the universal joint. The seal edge 26b on the base end side (the lower side in FIGS. 1 and 2) is prevented from moving across the step 28. In other words, the seal edge 26b on the base end side is in contact (sliding contact) only with the portion near the opening end of the outer peripheral surface of the bearing cup 11 and not covered with the coating film 25. . The coating operation for forming the coating film 25 is carried out in a neutral state in which no external force is applied (torque transmission is not performed) after assembling the constituent members of the universal joint. In this neutral state, each of the four bearing cups 11, seal rings 15a, and pins 22 constituting the universal joint is elastically deformed by substantially the same amount.

これに対して、自在継手の使用時に上記軸受カップ１１と上記軸部１２とは、これら軸受カップ１１と軸部１２との間に加わるスラスト荷重に基づき、軸方向に相対変位する。この相対変位は、この軸部１２と上記軸受カップ１１との間に設けた合成樹脂製のピン２２のスラスト方向の剛性、この軸受カップ１１のスラスト方向の剛性、上記シールリング１５ａのスラスト方向の剛性に抗して行われる。そして、上記十字軸９の変位方向前側に存在する各部材１１、１５ａ、２２の弾性変形量が増大し、同じく後側に存在する各部材１１、１５ａ、２２の弾性変形量が減少する。これら各部材１１、１５ａ、２２の剛性及び上記スラスト荷重は、計算により、或は実験により求められる。従って、自在継手の使用時に発生する、上記軸受カップ１１と上記軸部１２との軸方向に関する相対変位量（の最大値）に就いても、計算により、或は実験により求められる。 In contrast, when the universal joint is used, the bearing cup 11 and the shaft portion 12 are relatively displaced in the axial direction based on a thrust load applied between the bearing cup 11 and the shaft portion 12. This relative displacement is caused by the rigidity in the thrust direction of the synthetic resin pin 22 provided between the shaft portion 12 and the bearing cup 11, the rigidity in the thrust direction of the bearing cup 11, and the thrust direction of the seal ring 15a. This is done against rigidity. Then, the amount of elastic deformation of each member 11, 15a, 22 existing on the front side in the displacement direction of the cross shaft 9 is increased, and the amount of elastic deformation of each member 11, 15a, 22 also present on the rear side is decreased. The rigidity of each of the members 11, 15a, and 22 and the thrust load can be obtained by calculation or experiment. Therefore, the relative displacement amount (maximum value) in the axial direction between the bearing cup 11 and the shaft portion 12 that occurs when the universal joint is used can also be obtained by calculation or experiment.

本例の場合には、前記両シール縁２６ａ、２６ｂの軸方向距離Ｌ₂₆を、上述の様にして求められる、上記軸受カップ１１と上記軸部１２との、中立位置からの軸方向変位量の最大値Ｌ_MAX 以上（Ｌ₂₆≧Ｌ_MAX ）、好ましくはこの軸方向変位量の最大値Ｌ_MAX よりも少しだけ（例えば０．５mm程度）大きく（Ｌ₂₆＞Ｌ_MAX ）している。従って、前記ラジアルシールリップ１８ａの先端部に設けた１対のシール縁２６ａ、２６ｂのうちで、上記各軸受カップ１１の開口端寄りのシール縁２６ｂは、上記塗膜２５の端部に存在する段差２８を乗り越えて移動する事がなくなる。即ち、上記両シール縁２６ａ、２６ｂのうち、先端側のシール縁２６ａは、上記自在継手の使用時に、この段差２８を乗り越えつつ、上記軸受カップ１１の外周面に対し摺動する。従って、上記先端側のシール縁２６ａによるシール性能は悪化し易い。これに対して、基端側のシール縁２６ｂは、上記軸受カップ１１の外周面のうちで、上記塗膜２５により覆われていない部分にのみ当接（摺接）する。この為、上記基端側のシール縁２６ｂによるシール性を、上記段差２８の存在に関係なく、十分に確保できる。尚、上記軸方向距離Ｌ₂₆の最大値は、上記ラジアルシールリップ１８ａの先端縁がヨークの腕部と干渉しない範囲で、設計的に定める。 In the case of this example, the axial distance L ₂₆ between the seal edges 26a and 26b is obtained as described above, and the axial displacement amount from the neutral position between the bearing cup 11 and the shaft portion 12 is obtained. Is larger than the maximum value L _MAX (L ₂₆ ≧ L _MAX ), preferably slightly larger (for example, about 0.5 mm) than this maximum value L _MAX of the axial displacement (L ₂₆ > L _MAX ). Accordingly, among the pair of seal edges 26a and 26b provided at the tip of the radial seal lip 18a, the seal edge 26b near the opening end of each bearing cup 11 exists at the end of the coating film 25. It will not move over the step 28. That is, of the two seal edges 26a and 26b, the seal edge 26a on the distal end side slides with respect to the outer peripheral surface of the bearing cup 11 while overcoming the step 28 when the universal joint is used. Therefore, the sealing performance by the seal edge 26a on the tip side is likely to deteriorate. On the other hand, the seal edge 26b on the base end side comes into contact (sliding contact) only with a portion of the outer peripheral surface of the bearing cup 11 that is not covered with the coating film 25. For this reason, the sealing performance by the sealing edge 26b on the base end side can be sufficiently ensured regardless of the presence of the step 28. The maximum value of the axial distance L ₂₆ is determined in terms of design within a range where the tip edge of the radial seal lip 18a does not interfere with the arm portion of the yoke.

［実施の形態の第２例］
図３は、請求項１〜３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、ラジアルシールリップ１８ａの先端部に設けた１対のシール縁２６ａ、２６ｂの軸方向距離Ｌ_２６を、中立状態で、軸部１２の先端面と軸受カップ１１の底部２３ａの内面との間に存在する隙間２９の最小厚さＴ_２９との関係で規制している。即ち、上記軸方向距離Ｌ_２６を、この最小厚さＴ_２９以上（Ｌ_２６≧Ｔ_２９）、好ましくは、この最小厚さＴ_２９よりも少しだけ（例えば０．５mm程度）大きく（Ｌ_２６＞Ｔ_２９）している。 [Second Example of Embodiment]
FIG. 3 shows a second example of an embodiment of the present invention corresponding to claims 1 to 3 . In the case of this example, the axial distance L ₂₆ between the pair of seal edges 26a, 26b provided at the tip of the radial seal lip 18a is set to the neutral state, and the tip surface of the shaft 12 and the bottom 23a of the bearing cup 11 are in a neutral state. Is regulated by the relationship with the minimum thickness T ₂₉ of the gap 29 existing between the inner surface of the gap 29. That is, the axial distance L _{26 is set} to be equal to or greater than the minimum thickness T ₂₉ (L ₂₆ ≧ T ₂₉ ), and preferably slightly larger (for example, about 0.5 mm) than the minimum thickness T ₂₉ (L ₂₆ > and T ₂₉₎ and.

自在継手の使用時に上記軸部１２と上記軸受カップ１１とは、軸方向に相対変位するが、この軸部１２がこの軸受カップ１１内に入り込む方向の変位は、理論上は、この軸部１２の先端面がこの軸受カップ１１の底部２３ａの内面に当接する迄可能である。実際の場合には、上記隙間２９の最小厚さＴ₂₉によっては（最小厚さＴ₂₉が大きい場合には）上記軸部１２の先端面が上記底部２３ａの内面に当接する以前に、ピン２２の突っ張り力が自在継手の使用に伴って発生するスラスト荷重よりも大きくなって、上記軸部１２の先端面と上記底部２３ａの内面とが当接しない場合もある。 When the universal joint is used, the shaft portion 12 and the bearing cup 11 are relatively displaced in the axial direction. The displacement in the direction in which the shaft portion 12 enters the bearing cup 11 is theoretically the shaft portion 12. This is possible until the front end surface of the bearing abuts against the inner surface of the bottom 23a of the bearing cup 11. The actual case, before the front end surface of the above by the minimum thickness T ₂₉ of the gap 29 (if the minimum thickness T ₂₉ is large) the shaft portion 12 abuts the inner surface of the bottom portion 23a, the pin 22 In some cases, the thrust force of the shaft portion 12 becomes larger than the thrust load generated with the use of the universal joint, and the tip surface of the shaft portion 12 does not contact the inner surface of the bottom portion 23a.

逆に、上記最小厚さＴ₂₉が小さい場合には、上記ピン２２の突っ張り力が上記スラスト荷重よりも小さい間に、上記軸部１２の先端面と上記底部２３ａの内面とが当接する場合も考えられる。この様な場合、この底部２３ａの弾性変形に基づき、上記軸部１２が上記軸受カップ１１内に入り込む方向に変位する余地はある。但し、この軸部１２の先端面と上記底部２３ａの内面との当接部は、この底部２３ａのうちで、剛性が高い外径寄り部分である。この為、上述の様な弾性変形に基づく変位量は極く僅かで、殆ど無視できる。 On the other hand, when the minimum thickness T ₂₉ is small, the tip surface of the shaft portion 12 and the inner surface of the bottom portion 23a may come into contact while the tension force of the pin 22 is smaller than the thrust load. Conceivable. In such a case, there is room for the shaft portion 12 to be displaced in the direction of entering the bearing cup 11 based on the elastic deformation of the bottom portion 23a. However, the contact portion between the tip end surface of the shaft portion 12 and the inner surface of the bottom portion 23a is a portion of the bottom portion 23a near the outer diameter having high rigidity. For this reason, the amount of displacement based on the elastic deformation as described above is negligible and almost negligible.

以上の事を考慮すれば、本例の構造の様に、前記両シール縁２６ａ、２６ｂの軸方向距離Ｌ₂₆を、上記軸部１２の先端面と軸受カップ１１の底部２３ａの内面との間に存在する隙間２９の最小厚さＴ₂₉以上に設定すれば、上記両シール縁２６ａ、２６ｂのうちで基端側のシール縁２６ｂが、上記軸受カップ１１の外周面を覆う塗膜２５の端部に存在する段差２８（図２参照、図３には省略）を乗り越えて移動する可能性は殆どなくなる。そして、前述した実施の形態の第１例の場合と同様に、上記基端側のシール縁２６ｂによるシール性を、上記段差２８の存在に関係なく、十分に確保できる。又、仮に上記ピン２２がへたる事により、上記軸部１２の軸方向変位量が多くなっても、上記基端側のシール縁２６ｂによるシール性を確保できる（初期にピン２２の突っ張り力がスラスト荷重よりも大きい場合）。 Considering the above, as in the structure of this example, the axial distance L ₂₆ between the seal edges 26a and 26b is set between the tip surface of the shaft portion 12 and the inner surface of the bottom portion 23a of the bearing cup 11. If the gap T ₂₉ is set to be equal to or greater than the minimum thickness T ₂₉ , the seal edge 26 b on the proximal end side of the seal edges 26 a and 26 b is the end of the coating film 25 that covers the outer peripheral surface of the bearing cup 11. There is almost no possibility of moving over the step 28 (see FIG. 2 and omitted in FIG. 3) existing in the section. Further, as in the case of the first example of the above-described embodiment, the sealing performance by the base end side seal edge 26b can be sufficiently ensured regardless of the presence of the step 28. Further, if the pin 22 is bent, even if the axial displacement amount of the shaft portion 12 increases, the sealing performance by the seal edge 26b on the base end side can be ensured (the tensile force of the pin 22 is initially reduced). If greater than the thrust load).

［実施の形態の第３例］
図４は、請求項１、３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、軸受カップ１１と軸部１２との間に組み付けた合成樹脂製のピン２２ａの形状を、前述した実施の形態の第１例及び上述した実施の形態の第２例の場合と異ならせている。本例の構造に組み込む上記ピン２２ａは、先端部に外向フランジ状の鍔部３０を備えており、この鍔部３０を、上記軸部１２の先端面で挿入孔２１の開口周囲部分に突き当てている。又、上記ピン２２ａの先端面中央部に、突部３１を形成している。更に、上記ピン２２ａの基端部（図４の下端部）は小径にして、上記挿入孔２１の底面中央部に突き当てている。自在継手を組み立てて外力が作用しない中立状態では、この突部３１のみが上記軸受カップ１１の底部２３ａの内面中央部に当接し、上記鍔部３０とこの底部２３ａの内面とは、微小隙間を介して互いに離隔する。これに対して、上記自在継手の使用に伴って、上記軸部１２を上記軸受カップ１１内に押し込む方向のスラスト荷重が加わると、上記突部３１の弾性変形量（圧縮量）が増大し、上記鍔部３０と上記底部２３ａの内面とが当接する。この状態では、上記ピン２２ａのスラスト方向の剛性が向上する。 [Third example of embodiment]
FIG. 4 shows a third example of an embodiment of the present invention corresponding to claims 1 and 3 . In the case of this example, the shape of the synthetic resin pin 22a assembled between the bearing cup 11 and the shaft portion 12 is the same as that of the first example of the embodiment described above and the second example of the embodiment described above. It is different from the case. The pin 22a incorporated in the structure of this example is provided with a flange portion 30 having an outward flange shape at the distal end, and the flange portion 30 is abutted against the opening peripheral portion of the insertion hole 21 at the distal end surface of the shaft portion 12. ing. A protrusion 31 is formed at the center of the tip surface of the pin 22a. Further, the base end portion (the lower end portion in FIG. 4) of the pin 22a has a small diameter and abuts against the center portion of the bottom surface of the insertion hole 21. In a neutral state in which a universal joint is assembled and no external force is applied, only the protrusion 31 abuts on the center of the inner surface of the bottom 23a of the bearing cup 11, and a small gap is formed between the flange 30 and the inner surface of the bottom 23a. To be separated from each other. On the other hand, when a thrust load is applied in the direction in which the shaft portion 12 is pushed into the bearing cup 11 with the use of the universal joint, the elastic deformation amount (compression amount) of the protrusion 31 increases. The flange portion 30 and the inner surface of the bottom portion 23a abut. In this state, the rigidity of the pin 22a in the thrust direction is improved.

要するに本例の構造は、上記軸部１２を上記軸受カップ１１内に押し込む方向の力に関する剛性が、２段階に変化する。この為に本例の構造では、上記ピン２２ａによる緩衝作用を確保しつつ、上記スラスト荷重に基づいて上記軸部１２が上記軸受カップ１１内に押し込まれる量を小さくできる。従って、ラジアルシールリップ１８ａの先端部に設けた１対のシール縁２６ａ、２６ｂの軸方向距離Ｌ₂₆を短くしても、基端側のシール縁２６ｂが、上記軸受カップ１１の外周面を覆う塗膜２５の端部に存在する段差２８（図２参照、図４には省略）を乗り越えて移動する事を防止できる。従って、上記ラジアルシールリップ１８ａの先端部の小型化による、自在継手の小型化を図れる。 In short, in the structure of this example, the rigidity related to the force in the direction in which the shaft portion 12 is pushed into the bearing cup 11 changes in two stages. For this reason, in the structure of this example, the amount of the shaft portion 12 pushed into the bearing cup 11 based on the thrust load can be reduced while securing the buffering action by the pin 22a. Therefore, even if the axial distance L ₂₆ between the pair of seal edges 26 a and 26 b provided at the distal end portion of the radial seal lip 18 a is shortened, the proximal-side seal edge 26 b covers the outer peripheral surface of the bearing cup 11. It is possible to prevent movement over the step 28 (see FIG. 2, omitted in FIG. 4) present at the end of the coating film 25. Accordingly, it is possible to reduce the size of the universal joint by reducing the size of the tip of the radial seal lip 18a.

［実施の形態の第４例］
図５〜６は、請求項１に対応する、本発明の実施の形態の第４例を示している。本例は、合成樹脂製のピンを持たない構造に関し、本発明を適用した場合に就いて示している。本例の構造に組み込む軸受カップ１１ｂは、底部２３ｂの中央部を内側に膨出させる事により、この底部２３ｂの内面中央部に、部分球面状の凸部３２を形成している。そして、この凸部３２の中央部を、軸部１２の先端面中央部に当接させている。 [Fourth Example of Embodiment]
5 to 6 show a fourth example of the embodiment of the invention corresponding to the first aspect. This example relates to a structure that does not have a pin made of synthetic resin, and shows a case where the present invention is applied. The bearing cup 11b incorporated in the structure of this example forms a partially spherical convex portion 32 at the center of the inner surface of the bottom 23b by causing the center of the bottom 23b to bulge inward. The central portion of the convex portion 32 is brought into contact with the central portion of the tip end surface of the shaft portion 12.

この様な本例の構造の場合、自在継手の使用に伴って上記軸受カップ１１ｂと軸部１２との間にスラスト荷重が加わると、上記底部２３ｂの弾性変形に基づいて、これら軸受カップ１１ｂと軸部１２とが軸方向に相対変位する。この弾性変形に基づく相対変位量は僅かであるので、この弾性変形に基づく相対変位量だけを考慮すれば、ラジアルシールリップ１８ａの先端部に設けた１対のシール縁２６ａ、２６ｂの軸方向距離Ｌ_２６を極く短くできる。但し、本例の構造の場合には、長期間に亙る使用に伴って、上記凸部３２が次第に摩耗し、その分だけ、上記軸受カップ１１ｂ内への上記軸部１２の挿入量が増大する可能性がある。そこで本例の場合には、上記両シール縁２６ａ、２６ｂの軸方向距離Ｌ_２６を、上記底部２３ｂの弾性変形に基づく相対変位分と、上記摩耗に基づく相対変位分（最大で、上記凸部３２の高さ分）とを合計した長さとしている。この結果、長期間に亙る使用後に於いても、基端側のシール縁２６ｂが、上記軸受カップ１１ｂの外周面を覆う塗膜２５の端部に存在する段差２８（図２参照、図５〜６には省略）を乗り越えて移動する事を防止できる。 In the case of such a structure of this example, when a thrust load is applied between the bearing cup 11b and the shaft portion 12 in accordance with the use of the universal joint, the bearing cup 11b and the bearing cup 11b The shaft portion 12 is relatively displaced in the axial direction. Since the relative displacement amount based on the elastic deformation is small, the axial distance between the pair of seal edges 26a and 26b provided at the tip of the radial seal lip 18a is considered only by the relative displacement amount based on the elastic deformation. L ₂₆ can be made extremely short. However, in the case of the structure of this example, the convex portion 32 is gradually worn with use over a long period of time, and the amount of insertion of the shaft portion 12 into the bearing cup 11b increases accordingly. there is a possibility. Therefore, in the case of this example, the axial distance L ₂₆ between the seal edges 26a, 26b is set to a relative displacement amount based on the elastic deformation of the bottom portion 23b and a relative displacement amount based on the wear (maximum, the convex portion). 32 heights) is the total length. As a result, even after use over a long period of time, the seal edge 26b on the base end side has a step 28 (see FIG . 2, FIG. 5) that exists at the end of the coating film 25 that covers the outer peripheral surface of the bearing cup 11b . It is possible to prevent the vehicle from moving over (omitted from 6 ).

［実施の形態の第５例］
図７は、請求項１に対応する、本発明の実施の形態の第５例を示している。本例は、合成樹脂製のピンを持たず、しかも、軸部１２の先端面と軸受カップ１１の底部２３ａの内面との間を単なる空間とした構造に、本発明を適用した場合に就いて示している。この様な構造の場合、自在継手に外力が加わらない中立状態では、シールリング１５ａを構成するスラストシールリップ１９の弾力のみにより、上記軸部１２と上記軸受カップ１１との位置関係が中立状態となる。 [Fifth Example of Embodiment]
FIG. 7 shows a fifth example of the embodiment of the present invention corresponding to the first aspect. This example relates to a case where the present invention is applied to a structure that does not have a pin made of a synthetic resin and has a simple space between the tip surface of the shaft portion 12 and the inner surface of the bottom portion 23a of the bearing cup 11. Show. In such a structure, in a neutral state where no external force is applied to the universal joint, the positional relationship between the shaft portion 12 and the bearing cup 11 is neutral only by the elastic force of the thrust seal lip 19 constituting the seal ring 15a. Become.

この様な構造に本発明を適用する為に本例の場合には、前述の図３に示した実施の形態の第２例と同様に、ラジアルシールリップ１８ａの先端部に設けた１対のシール縁２６ａ、２６ｂの軸方向距離Ｌ_２６を、中立状態での、軸部１２の先端面と軸受カップ１１の底部２３ａの内面との間に存在する隙間２９の最小厚さＴ_２９以上（Ｌ_２６≧Ｔ_２９）、好ましくは、この最小厚さＴ_２９よりも少しだけ（例えば０．５mm程度）大きく（Ｌ_２６＞Ｔ_２９）する。この為、上記両シール縁２６ａ、２６ｂのうちで基端側のシール縁２６ｂが、上記軸受カップ１１の外周面を覆う塗膜２５の端部に存在する段差２８（図２参照、図７には省略）を乗り越えて移動する可能性は殆どなくなり、上記基端側のシール縁２６ｂによるシール性を、上記段差２８の存在に関係なく、十分に確保できる。 In the case of the present example in order to apply the present invention to such a structure, as in the second example of the embodiment shown in FIG. The axial distance L ₂₆ between the seal edges 26a and 26b is set to be equal to or greater than the minimum thickness T ₂₉ of the gap 29 existing between the tip end surface of the shaft portion 12 and the inner surface of the bottom portion 23a of the bearing cup 11 in the neutral state (L ₂₆ ≧ T ₂₉ ), preferably slightly larger than this minimum thickness T ₂₉ (for example, about 0.5 mm) (L ₂₆ > T ₂₉ ). For this reason, of the two seal edges 26a, 26b, the seal edge 26b on the proximal end side is a step 28 (see FIG. 2 and FIG. 7) present at the end of the coating film 25 covering the outer peripheral surface of the bearing cup 11. The possibility of moving over the other is almost eliminated, and the sealing performance by the sealing edge 26b on the base end side can be sufficiently ensured regardless of the presence of the step 28.

本発明は、ステアリング装置用の自在継手に限らず、各種導力伝達装置の非直線接続部に組み込まれる十字軸式の自在継手に適用できる。 The present invention is not limited to a universal joint for a steering device, but can be applied to a cross-shaft type universal joint that is incorporated in a non-linear connection portion of various conductive force transmission devices.

本発明の実施の形態の第１例を示す、図１０のＡ−Ａ断面に相当する図。The figure equivalent to the AA cross section of FIG. 10 which shows the 1st example of embodiment of this invention. 図１のＢ部拡大図。The B section enlarged view of FIG. 本発明の実施の形態の第２例を示す、図１の右部に相当する図。The figure equivalent to the right part of FIG. 1 which shows the 2nd example of embodiment of this invention. 同第３例を示す、図１と同様の図。The figure similar to FIG. 1 which shows the 3rd example. 同第４例を示す、図１と同様の図。The figure similar to FIG. 1 which shows the 4th example. 図５の右部拡大図。The right part enlarged view of FIG. 本発明の実施の形態の第５例を示す、図１と同様の図。The figure similar to FIG. 1 which shows the 5th example of embodiment of this invention. 自在継手を組み込んだステアリング装置の１例を示す斜視図。The perspective view which shows an example of the steering device incorporating a universal joint. 従来から知られている自在継手の第１例を示す、部分切断側面図。The partial cut side view which shows the 1st example of the universal joint known conventionally. 一部を省略して示す、図９の拡大Ｃ−Ｃ断面図。FIG. 10 is an enlarged CC cross-sectional view of FIG. 従来から知られている自在継手の第２例を示す、図１０の下端部に相当する図。The figure equivalent to the lower end part of FIG. 10 which shows the 2nd example of the universal joint known conventionally. 従来構造の問題点を説明する為の、図２と同様の図。The same figure as FIG. 2 for demonstrating the problem of a conventional structure.

１ステアリングホイール
２ステアリングシャフト
３自在継手
４中間シャフト
５ステアリングギヤユニット
６入力軸
７タイロッド
８ａ、８ｂヨーク
９十字軸
１０円孔
１１、１１ａ、１１ｂ軸受カップ
１２軸部
１３結合基部
１４ラジアル軸受
１５、１５ａシールリング
１６芯金
１７、１７ａ弾性材
１８、１８ａラジアルシールリップ
１９スラストシールリップ
２０内向鍔部
２１挿入孔
２２、２２ａピン
２３、２３ａ、２３ｂ底部
２４突条
２５塗膜
２６ａ、２６ｂシール縁
２７凹溝
２８段差
２９隙間
３０鍔部
３１突部
３２凸部 DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Steering shaft 3 Universal joint 4 Intermediate shaft 5 Steering gear unit 6 Input shaft 7 Tie rod 8a, 8b Yoke 9 Cross shaft 10 Circular hole 11, 11a, 11b Bearing cup 12 Shaft part 13 Connection base part 14 Radial bearing 15, 15a Seal ring 16 Core 17, 17 a Elastic material 18, 18 a Radial seal lip 19 Thrust seal lip 20 Inward flange 21 Insert hole 22, 22 a Pin 23, 23 a, 23 b Bottom 24 Projection 25 Coating film 26 a, 26 b Seal edge 27 Concave Groove 28 Step 29 Clearance 30 Gutter 31 Projection 32 Projection

Claims

A pair of yokes each formed in a bifurcated shape, four circular holes formed concentrically with each other at both ends of both yokes, and inside each of these circular holes with the openings facing each other Four bearing cups each having a bottomed cylindrical shape that are internally fitted and fixed, and four shaft portions are radially fixed on the outer peripheral surface of the coupling base portion. A cross shaft combined with both yokes in a state of being inserted into each bearing cup, and four sets of radial bearings provided between the inner peripheral surface of each bearing cup and the outer peripheral surface of each shaft portion; Four seal rings provided between the base end portions of the shaft portions and the opening portions of the bearing cups in a state in which the base portions are externally supported by the base end portions of the shaft portions. Each of these seal rings has an entire circumference at the end near the opening of the outer peripheral surface of each of the bearing cups. In a universal joint whose surface is coated with the seal lip of each seal lip in contact with the outer peripheral surface of each bearing cup, the seal lip is provided. However, the tip portion is formed in a bifurcated manner and has a pair of seal edges that are spaced apart in the axial direction, and the distance between the pair of seal edges provided at the tip portions of the respective seal lips in the axial direction. The shaft portion and the bearing cup at the time of use are more than the axial displacement amount from the neutral position in the direction in which the insertion amount of the shaft portion into the bearing cup increases. A universal joint.

The minimum thickness of the gap that exists between the tip end surface of each shaft portion and the bottom inner surface of each bearing cup when the axial interval between a pair of seal edges provided at the tip portion of each seal lip is in a neutral state The universal joint according to claim 1 , which is equal to or larger than the above.

A bottomed insertion hole is formed inside each shaft portion in the axial direction of each shaft portion so as to open to the end face of each shaft portion, and one end of each of the shaft portions is inserted into each insertion hole. The universal joint according to any one of claims 1 and 2 , wherein the other end of the synthetic resin pin abutted against the back end of the insertion hole is abutted against the bottom inner surface of each bearing cup.