JP2013252860A - Method of manufacturing impact absorbing steering shaft - Google Patents

Method of manufacturing impact absorbing steering shaft Download PDF

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JP2013252860A
JP2013252860A JP2013175766A JP2013175766A JP2013252860A JP 2013252860 A JP2013252860 A JP 2013252860A JP 2013175766 A JP2013175766 A JP 2013175766A JP 2013175766 A JP2013175766 A JP 2013175766A JP 2013252860 A JP2013252860 A JP 2013252860A
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shaft
diameter portion
tip
end portion
peripheral surface
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JP5733360B2 (en
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Hiromichi Komori
宏道 小森
Kiyoshi Sadakata
清 定方
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NSK Ltd
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NSK Ltd
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Abstract

PROBLEM TO BE SOLVED: To provide an impact absorbing steering shaft capable of smoothly performing relative displacement in the axial direction between an outer shaft 12a and an inner shaft 13a due to an impact load accompanied with a secondary collision, and to provide a method of manufacturing the impact absorbing steering shaft.SOLUTION: The top end part of a large diameter part 16a of an inner shaft 13a is internally fitted and is fixed to the base end part of a small diameter part 14 of an outer shaft 12a with such a fitting strength that the outer shaft 12a and the inner shaft 13a can relatively displace each other in the axial direction in accordance with a shock applied upon a secondary collision. A chamfered part 21 is provided on the outer periphery of the top end part of the large diameter part 16a and, the outer diameter of the large diameter part 16a is reduced toward the top end edge of the large diameter part 16a. Thus, when both shafts 12a, 13a are assembled to each other, galling of the inner circumferential surface of the small diameter part 14 by the top end edge of the large diameter part 16a is prevented.

Description

この発明は、自動車のステアリング装置を構成する衝撃吸収式ステアリングシャフト及びその製造方法の改良に関する。具体的には、このステアリングシャフトを製造する際に、インナシャフトの先端縁とアウタシャフトの内周面との間にかじりが発生するのを防止して、前記ステアリングシャフトの製造コストの増大を抑えつつ、衝撃吸収性能を安定させられる構造及びその製造方法を実現するものである。尚、本発明の対象となるステアリングシャフトには、ステアリングコラムの内側に支持されるものだけでなく、ステアリングコラムの前側に配置される中間シャフトも含む。   The present invention relates to an impact-absorbing steering shaft constituting an automobile steering device and an improvement of a manufacturing method thereof. Specifically, when manufacturing this steering shaft, the occurrence of galling between the inner edge of the inner shaft and the outer peripheral surface of the outer shaft is prevented, thereby suppressing an increase in the manufacturing cost of the steering shaft. In addition, a structure capable of stabilizing the shock absorbing performance and a manufacturing method thereof are realized. Note that the steering shaft that is an object of the present invention includes not only a shaft supported on the inside of the steering column but also an intermediate shaft disposed on the front side of the steering column.

操舵輪(フォークリフト等の特殊車両を除き、通常は前輪)に舵角を付与する為のステアリング装置として、例えば図6に示す様な構造が、広く知られている。このステアリング装置は、車体1に支持された円筒状のステアリングコラム2の内径側にステアリングシャフト3を、回転可能に支持している。そして、このステアリングコラム2の後端開口よりも後方に突出した、前記ステアリングシャフト3の後端部分に、ステアリングホイール4を固定している。このステアリングホイール4を回転させると、この回転が、前記ステアリングシャフト3、自在継手5a、中間シャフト6、自在継手5bを介して、ステアリングギヤユニット7の入力軸8に伝達される。この入力軸8が回転すると、このステアリングギヤユニット7の両側に配置された1対のタイロッド9、9が押し引きされて左右1対の操舵輪に、前記ステアリングホイール4の操作量に応じた舵角を付与する。尚、図6に示した構造の場合、このステアリングホイール4の前後位置の調節を可能にすべく、前記ステアリングコラム2及び前記ステアリングシャフト3として、伸縮式のものを使用している。又、上述の様なステアリング装置に、電気モータ10を補助動力源として組み込んだ電動式パワーステアリング装置も、近年普及している。   For example, a structure as shown in FIG. 6 is widely known as a steering device for giving a steering angle to a steered wheel (usually a front wheel except a special vehicle such as a forklift). In this steering device, a steering shaft 3 is rotatably supported on the inner diameter side of a cylindrical steering column 2 supported by a vehicle body 1. A steering wheel 4 is fixed to the rear end portion of the steering shaft 3 protruding rearward from the rear end opening of the steering column 2. When the steering wheel 4 is rotated, this rotation is transmitted to the input shaft 8 of the steering gear unit 7 via the steering shaft 3, the universal joint 5a, the intermediate shaft 6, and the universal joint 5b. When the input shaft 8 rotates, a pair of tie rods 9, 9 arranged on both sides of the steering gear unit 7 are pushed and pulled, and a steering wheel according to the operation amount of the steering wheel 4 is turned to a pair of left and right steering wheels. Give a corner. In the case of the structure shown in FIG. 6, telescopic type is used as the steering column 2 and the steering shaft 3 in order to enable adjustment of the front-rear position of the steering wheel 4. In addition, in recent years, an electric power steering apparatus in which the electric motor 10 is incorporated as an auxiliary power source in the steering apparatus as described above has also become widespread.

前記ステアリングコラム2及び前記ステアリングシャフト3は、衝突事故の際に、衝撃エネルギを吸収しつつ、ステアリングホイール4を前方に変位させる構造としている。即ち、衝突事故の際には、自動車が他の自動車等にぶつかる一次衝突に続いて、運転者の身体がステアリングホイール4に衝突する二次衝突が発生する。この二次衝突の際に、運転者の身体に加わる衝撃を緩和して、運転者の保護を図る為に、前記ステアリングホイール4を支持したステアリングシャフト3を車体1に対して、二次衝突に伴う前方への衝撃荷重により前方に変位可能に支持する必要がある。この為に、前記ステアリングコラム2は、二次衝突の衝撃荷重により、アウタコラム11がこのステアリングコラム2の全長を、前記ステアリングシャフト3は、アウタシャフト12がこのステアリングシャフト3の全長を、それぞれ縮めながら前方に変位する事で、前記ステアリングホイール4に衝突した運転者の身体に大きな衝撃が加わる事を防止する。
上述の様な伸縮式のステアリングコラムを構成するアウタコラム及びインナコラム、並びに、ステアリングシャフトを構成するアウタシャフト及びインナシャフトの前後位置は、図示の構造とは逆であっても良い。上述の様な伸縮式のステアリングシャフトを製造する為の技術として、例えば特許文献1〜2に記載の技術がある。
The steering column 2 and the steering shaft 3 are configured to displace the steering wheel 4 while absorbing impact energy in the event of a collision. That is, in the event of a collision accident, a secondary collision in which the driver's body collides with the steering wheel 4 occurs following a primary collision in which the automobile collides with another automobile or the like. In order to alleviate the impact applied to the driver's body during the secondary collision and to protect the driver, the steering shaft 3 supporting the steering wheel 4 is subjected to the secondary collision with respect to the vehicle body 1. It is necessary to support it so that it can be displaced forward by a forward impact load. For this reason, the steering column 2 is contracted by the impact load of the secondary collision, the outer column 11 is shortened by the entire length of the steering column 2, and the steering shaft 3 is contracted by the outer shaft 12 by the total length of the steering shaft 3. However, a large impact is prevented from being applied to the driver's body colliding with the steering wheel 4 by being displaced forward.
The outer column and the inner column that constitute the telescopic steering column as described above, and the front and rear positions of the outer shaft and the inner shaft that constitute the steering shaft may be opposite to the illustrated structure. As a technique for manufacturing the telescopic steering shaft as described above, there are techniques described in Patent Documents 1 and 2, for example.

図7〜10は、このうちの特許文献1に記載されている、衝撃吸収式のステアリングシャフト及びその製造方法の従来例を示している。ステアリングシャフト3aは、アウタシャフト12aとインナシャフト13とを軸方向に相対変位可能に係合させ、二次衝突時に、軸方向に加わる衝撃荷重により全長が縮まる様に構成している。
前記アウタシャフト12aは、全体を円管状とし、一端部(図7〜8の左端部)に絞り加工を施す事で、この一端部に小径部14を形成している。この小径部14の内周面には、雌セレーション15を形成している。又、前記インナシャフト13も、全体を円管状とし、一端部(図7〜8の右端部)を押し拡げる事で、この一端部に大径部16を形成している。この大径部16の外周面には、前記雌セレーション15と係合する雄セレーション17を形成している。
7 to 10 show a conventional example of an impact absorbing steering shaft and a manufacturing method thereof described in Patent Document 1 among them. The steering shaft 3a is configured such that the outer shaft 12a and the inner shaft 13 are engaged with each other so as to be relatively displaceable in the axial direction, and the total length is shortened by an impact load applied in the axial direction at the time of a secondary collision.
The outer shaft 12a has a circular tube shape as a whole, and a small diameter portion 14 is formed at one end portion by drawing one end portion (left end portion in FIGS. 7 to 8). A female serration 15 is formed on the inner peripheral surface of the small diameter portion 14. The inner shaft 13 is also formed in a circular tube shape as a whole, and a large-diameter portion 16 is formed at one end by expanding one end (the right end in FIGS. 7 to 8). A male serration 17 that engages with the female serration 15 is formed on the outer peripheral surface of the large diameter portion 16.

この様なアウタシャフト12aとインナシャフト13とを組み合わせて、図7に示す様なステアリングシャフト3aを製造する場合には、先ず、図8に示す様に、前記雌セレーション15と前記雄セレーション17とを、前記小径部14の先端部(図8の左端部)と前記大径部16の先端部(図8の右端部)とで互いに係合させる。
そして、前記両セレーション15、17同士を互いに係合させた状態のまま、前記小径部14の先端部の外周面を径方向内方に押圧する。即ち、この小径部14の先端部及び前記大径部16の先端部の周囲に1対の押圧片18、18を配置し、これら両押圧片18、18を互いに近づけ合う事で、前記小径部14の先端部の外周面を強く押圧する。これら両押圧片18、18の内側面でこの小径部14の先端部の外周面と当接する部分には、この外周面に当接する部分の断面形状が円弧状である、凹部19、19を形成している。
When the steering shaft 3a as shown in FIG. 7 is manufactured by combining such an outer shaft 12a and the inner shaft 13, first, as shown in FIG. 8, the female serration 15 and the male serration 17 Are engaged with each other at the distal end portion (left end portion in FIG. 8) of the small diameter portion 14 and the distal end portion (right end portion in FIG. 8) of the large diameter portion 16.
And the outer peripheral surface of the front-end | tip part of the said small diameter part 14 is pressed to radial direction inward with the said both serrations 15 and 17 being mutually engaged. That is, a pair of pressing pieces 18, 18 are arranged around the distal end portion of the small diameter portion 14 and the distal end portion of the large diameter portion 16, and the two small pressing portions 18, 18 are brought close to each other, whereby the small diameter portion 14 strongly presses the outer peripheral surface of the tip portion. On the inner side surfaces of these pressing pieces 18, 18 are formed recesses 19, 19 in which the cross-sectional shape of the portion contacting the outer peripheral surface is arcuate in the portion contacting the outer peripheral surface of the tip of the small diameter portion 14 doing.

図9に示す様に、これら両凹部19、19を前記小径部14の先端部の外周面に軽く当接させた状態で、前記両押圧片18、18の端面同士の間に、厚さがtの隙間20、20が形成される。この状態から、これら両押圧片18、18を、図示しない押圧装置により、互いに近づく方向に強く押圧する。そして、図10に示す様に、前記両隙間20、20の厚さが0となるまで、前記両押圧片18、18同士を互いに近づけ、前記小径部14の先端部の断面形状を、図10に示す様な楕円形に塑性変形させる。同時に、この小径部14の先端部に挿入された大径部16の先端部も、前記両セレーション15、17を介して押圧し、この大径部16の先端部の断面形状も、図10に示す様な楕円形に塑性変形させる。   As shown in FIG. 9, the thickness between the end faces of the two pressing pieces 18, 18 with both the recesses 19, 19 being in light contact with the outer peripheral surface of the distal end portion of the small diameter portion 14. T gaps 20 and 20 are formed. From this state, both the pressing pieces 18, 18 are strongly pressed in a direction approaching each other by a pressing device (not shown). Then, as shown in FIG. 10, the pressing pieces 18 and 18 are brought close to each other until the thickness of the gaps 20 and 20 becomes 0, and the cross-sectional shape of the distal end portion of the small diameter portion 14 is shown in FIG. It is plastically deformed into an oval shape as shown in. At the same time, the distal end portion of the large diameter portion 16 inserted into the distal end portion of the small diameter portion 14 is also pressed through the both serrations 15 and 17, and the sectional shape of the distal end portion of the large diameter portion 16 is also shown in FIG. Plastically deform into an elliptical shape as shown.

この様にして、前記小径部14の先端部及び前記大径部16の先端部を径方向内方に押圧し、これら両先端部の断面形状を楕円形に塑性変形させたならば、次いで、前記アウタシャフト12aと前記インナシャフト13とを互いに近づく方向に軸方向に相対変位させる。即ち、前記両押圧片18、18から前記アウタシャフト12aと前記インナシャフト13とを取り出した後、このアウタシャフト12aを図8の左方に、このインナシャフト13を同じく右方に、相手部材に対して相対変位させる。そして、図7に示す様に、前記小径部14の先端部を前記大径部16の基端部に圧入嵌合すると共に、この大径部16の先端部をこの小径部14の基端部に圧入嵌合させる。前記両押圧片18、18により塑性変形させられていない、この小径部14の中間部と前記大径部16の中間部とは互いに緩く係合させる。
尚、上述の様な衝撃吸収式ステアリングシャフトを構成するインナシャフト13は、アウタシャフト12aよりも外径が小さいので、強度を確保する為、S35C等硬度の高い炭素鋼により形成する事が多い。或いは、STKM12B等の炭素鋼鋼管により形成する事もできるが、この場合は強度を確保する為、径方向の厚さを厚くする。
In this way, if the distal end portion of the small diameter portion 14 and the distal end portion of the large diameter portion 16 are pressed radially inward, and the cross-sectional shape of both the distal end portions is plastically deformed into an elliptical shape, then, The outer shaft 12a and the inner shaft 13 are relatively displaced in the axial direction so as to approach each other. That is, after the outer shaft 12a and the inner shaft 13 are taken out from both the pressing pieces 18, 18, the outer shaft 12a is placed on the left side of FIG. The relative displacement is made. As shown in FIG. 7, the distal end portion of the small diameter portion 14 is press-fitted into the proximal end portion of the large diameter portion 16, and the distal end portion of the large diameter portion 16 is replaced with the proximal end portion of the small diameter portion 14. Press-fit into. The intermediate portion of the small diameter portion 14 and the intermediate portion of the large diameter portion 16 that are not plastically deformed by the two pressing pieces 18 and 18 are loosely engaged with each other.
Since the inner shaft 13 constituting the shock absorbing steering shaft as described above has a smaller outer diameter than the outer shaft 12a, it is often formed of carbon steel having a high hardness such as S35C in order to ensure strength. Alternatively, it can be formed of a carbon steel pipe such as STKM12B. In this case, the radial thickness is increased in order to ensure strength.

以上の説明は、後端部分にステアリングホイール4(図6参照)を固定するステアリングシャフト3に就いて行ったが、ステアリング装置の前側部分に配置される中間シャフト6も同様にして、軸方向に収縮可能に構成する場合がある。この様な収縮式(衝撃吸収式)の中間シャフト6は、自動車が他の自動車等にぶつかる一次衝突の際に、この一次衝突に伴う衝撃荷重よりその全長を縮める事で、前記ステアリングホイール4が運転者側に突き上げられるのを防止し、運転者の保護を図る。尚、前記中間シャフト6は、運転者の操作によって前記ステアリングホイール4から前記ステアリングシャフト3に付与されるトルクに加え、補助動力源である電動モータ10の出力トルクを伝達する。この為、上述の様な衝撃吸収式ステアリングシャフトを、前記中間シャフト6に適用する場合、前記アウタシャフト12aとインナシャフト13との係合部の保持力(嵌合強度)を大きくし、耐久性を高くする必要がある。この結果、前記大径部16の先端部外周縁(尖鋭な端縁)と、前記小径部14の内周面との当接圧が高くなり、上述の様な衝撃吸収式ステアリングシャフトの製造方法を実施する場合に於いて、前記アウタシャフト12aとインナシャフト13とを互いに近づく方向に軸方向に相対変位させる際に、前記大径部16の先端部外周縁でかじりが発生し易い。即ち、この相対変位の際、断面形状が楕円形であるこの大径部16の先端部外周縁の長径部分と、断面形状が円形である前記小径部14の内周面とが強く擦れ合って、この先端部外周縁がこの小径部14の内周面に食い込む(かじる)。この様にして発生したかじりを放置すると、衝突事故の際のエネルギ吸収性能が不安定になる可能性がある。そこでこのエネルギ吸収性能を安定させる為に、かじりにより生じた余肉部分(むしれ部分)を切削等により除去する手間が必要になる。又、かじりの程度によっては、完成後の衝撃吸収式ステアリングシャフトを、不良品として廃棄しなければならなくなり、加工の手間の増大や歩留りの悪化により、製造コストが上昇する為、改良が望まれる。特に、前記中間シャフト6の場合、前述した様に、保持力確保の為に嵌合部の当接圧を高くする為、改良する必要性が大きい。   Although the above description has been given with respect to the steering shaft 3 that fixes the steering wheel 4 (see FIG. 6) to the rear end portion, the intermediate shaft 6 disposed in the front portion of the steering device is similarly axially arranged. It may be configured to be shrinkable. Such a contraction type (shock absorption type) intermediate shaft 6 reduces the total length of the steering wheel 4 from the impact load associated with the primary collision at the time of the primary collision when the automobile collides with another automobile or the like. The driver is prevented from being pushed up to protect the driver. The intermediate shaft 6 transmits the output torque of the electric motor 10 as an auxiliary power source in addition to the torque applied from the steering wheel 4 to the steering shaft 3 by the operation of the driver. For this reason, when the shock absorbing steering shaft as described above is applied to the intermediate shaft 6, the holding force (fitting strength) of the engaging portion between the outer shaft 12a and the inner shaft 13 is increased, and the durability is improved. Need to be high. As a result, the contact pressure between the outer peripheral edge (sharp edge) of the distal end portion of the large-diameter portion 16 and the inner peripheral surface of the small-diameter portion 14 increases, and the method for manufacturing the shock absorbing steering shaft as described above When the outer shaft 12a and the inner shaft 13 are relatively displaced in the axial direction in the direction approaching each other, galling is likely to occur at the outer peripheral edge of the distal end portion of the large diameter portion 16. That is, at the time of this relative displacement, the long diameter portion of the outer peripheral edge of the distal end portion of the large diameter portion 16 having an elliptical cross-sectional shape and the inner peripheral surface of the small diameter portion 14 having a circular cross sectional shape are strongly rubbed. The outer peripheral edge of the tip portion bites into the inner peripheral surface of the small diameter portion 14. If the galling generated in this way is left unattended, the energy absorption performance in the event of a collision may become unstable. Therefore, in order to stabilize the energy absorption performance, it is necessary to remove a surplus portion (peeling portion) generated by galling by cutting or the like. Also, depending on the degree of galling, the completed shock absorbing steering shaft must be discarded as a defective product, which increases manufacturing costs due to increased processing effort and yield, and improvements are desired. . In particular, in the case of the intermediate shaft 6, as described above, there is a great need for improvement in order to increase the contact pressure of the fitting portion in order to secure the holding force.

特許第3168841号公報Japanese Patent No. 3168841 特許第3716590号公報Japanese Patent No. 3716590

本発明は、上述の様な事情に鑑み、アウタシャフトとインナシャフトとを、二次衝突時に加わる衝撃荷重に伴い、これら両シャフト同士が軸方向に相対変位可能に結合して成る衝撃吸収式ステアリングシャフトに於いて、このステアリングシャフトを製造する際に、前記インナシャフトの先端部外周縁と前記アウタシャフトの内周面との間にかじりが発生するのを防止し、加工の手間の増大や不良品の発生を抑えつつ、エネルギ吸収性能の安定した衝撃吸収式ステアリングシャフトを得られる様にして、製造コストの上昇を抑える事ができる構造及びその製造方法を実現すべく発明したものである。   In view of the circumstances as described above, the present invention is an impact-absorbing steering system in which an outer shaft and an inner shaft are coupled to each other so as to be capable of relative displacement in the axial direction in accordance with an impact load applied during a secondary collision. When manufacturing this steering shaft, it is possible to prevent galling between the outer peripheral edge of the inner shaft and the inner peripheral surface of the outer shaft. The present invention has been invented to realize a structure that can suppress an increase in manufacturing cost and a manufacturing method thereof so that an impact-absorbing steering shaft having stable energy absorption performance can be obtained while suppressing generation of non-defective products.

本発明の衝撃吸収式ステアリングシャフト及びその製造方法のうち、請求項1に記載した衝撃吸収式ステアリングシャフトは、管状のアウタシャフトと、インナシャフトとを、二次衝突時に加わる衝撃に伴い、これら両シャフト同士が軸方向に相対変位可能に結合して成る。
特に、本発明の衝撃吸収式ステアリングシャフトに於いては、前記インナシャフトの先端部のうち、先端縁寄り部分の外径を先端縁に向かう程小さくしている。
Among the shock absorbing steering shaft and the manufacturing method thereof according to the present invention, the shock absorbing steering shaft described in claim 1 includes a tubular outer shaft and an inner shaft, both of which are subjected to an impact applied during a secondary collision. The shafts are coupled so as to be capable of relative displacement in the axial direction.
In particular, in the shock absorbing type steering shaft of the present invention, the outer diameter of the tip end portion of the inner shaft is made smaller toward the tip end portion.

上述の様な本発明を実施する場合に、例えば請求項2に記載した発明の様に、前記アウタシャフトの一端部に少なくとも内径が小さい小径部を設け、前記インナシャフトの一端部に少なくとも外径が大きい大径部を設ける。そして、この大径部の先端部のうち、先端縁寄り部分の外径を先端縁に向かう程小さくする。   When carrying out the present invention as described above, for example, as in the invention described in claim 2, at least one small-diameter portion having a small inner diameter is provided at one end portion of the outer shaft, and at least an outer diameter is provided at one end portion of the inner shaft. A large-diameter portion having a large diameter is provided. Then, the outer diameter of the portion near the tip edge of the tip portion of the large diameter portion is made smaller toward the tip edge.

又、請求項3に記載した衝撃吸収式ステアリングシャフトの製造方法は、アウタシャフトの先端部とインナシャフトの先端部とを係合させた状態で、このアウタシャフトの先端部の外周面を径方向内方に(径方向反対位置を互いに近付く方向に)押圧し、このアウタシャフトの先端部及び前記インナシャフトの先端部を径方向に(押圧方向が短径でこれと直角方向が長径となる、断面楕円形に)塑性変形させる。次いで、前記両シャフト同士を互いに近づく方向に軸方向に相対変位させる。そして、前記アウタシャフトの先端部を前記インナシャフトの中間部に、このインナシャフトの先端部をこのアウタシャフトの中間部に、それぞれ圧入嵌合させる。このアウタシャフトの先端部と中間部との間部分と、前記インナシャフトの先端部と中間部との間部分とは、互いに緩く係合させる。
特に、請求項3に記載した衝撃吸収式ステアリングシャフトの製造方法に於いては、前記インナシャフトとして、このインナシャフトの先端部のうち、先端縁寄り部分の外径が先端縁に向かう程小さくなっているものを使用する。
According to a third aspect of the present invention, there is provided a shock absorbing steering shaft manufacturing method in which the outer peripheral surface of the outer shaft tip portion is radially aligned with the outer shaft tip portion engaged with the inner shaft tip portion. Pressing inward (in the direction of approaching each other in the radial direction), the outer shaft tip and the inner shaft tip in the radial direction (the pressing direction is the short diameter and the direction perpendicular thereto is the long diameter, Plastically deformed into an elliptical cross section. Next, the shafts are relatively displaced in the axial direction so as to approach each other. And the front-end | tip part of the said outer shaft is press-fitted and fitted to the intermediate part of the said inner shaft, and the front-end | tip part of this inner shaft is each press-fitted to the intermediate part of this outer shaft. A portion between the front end portion and the intermediate portion of the outer shaft and a portion between the front end portion and the intermediate portion of the inner shaft are loosely engaged with each other.
In particular, in the method of manufacturing the shock absorbing steering shaft according to claim 3, as the inner shaft, the outer diameter of the inner end portion of the inner shaft closer to the front end edge becomes smaller toward the front end edge. Use what you have.

上述の様な請求項3に記載の衝撃吸収式ステアリングシャフトの製造方法を実施する場合に、例えば請求項4に記載した発明の様に、前記アウタシャフトとして、一端部に少なくとも内径が小さい小径部を設けたものを、前記インナシャフトとして、一端部に少なくとも外径が大きい大径部を設け、この大径部の先端部のうち、少なくとも先端縁寄り部分の外径が先端縁に向かう程小さいものを、それぞれ使用する。そして、前記小径部の先端部と前記大径部の先端部とを係合させた状態で、この小径部の先端部の外周面を径方向内方に(径方向反対位置を互いに近付く方向に)押圧し、この小径部の先端部及び前記大径部の先端部を径方向に(押圧方向が短径でこれと直角方向が長径となる、断面楕円形に)塑性変形させる。次いで、前記両シャフト同士を互いに近づく方向に軸方向に相対変位させ、前記小径部の先端部を前記大径部の基端部に、この大径部の先端部をこの小径部の基端部に、それぞれ圧入嵌合させ、この小径部の中間部とこの大径部の中間部とを互いに緩く係合させる。   When carrying out the manufacturing method of the shock absorbing steering shaft according to claim 3 as described above, for example, as in the invention described in claim 4, the outer shaft has a small diameter portion with a small inner diameter at least at one end. As the inner shaft, a large-diameter portion having at least a large outer diameter is provided at one end portion, and at least the outer diameter of the portion near the tip edge of the tip portion of the large-diameter portion is small toward the tip edge. Use each one. Then, with the tip portion of the small diameter portion and the tip portion of the large diameter portion engaged, the outer peripheral surface of the tip portion of the small diameter portion is directed radially inward (in the direction in which the opposite radial positions approach each other). ) Press and plastically deform the tip of the small-diameter portion and the tip of the large-diameter portion in the radial direction (in a cross-sectional ellipse in which the pressing direction is the short diameter and the direction perpendicular thereto is the long diameter). Next, the shafts are relatively displaced in the axial direction so as to approach each other, the distal end portion of the small diameter portion is the proximal end portion of the large diameter portion, and the distal end portion of the large diameter portion is the proximal end portion of the small diameter portion The intermediate portion of the small diameter portion and the intermediate portion of the large diameter portion are loosely engaged with each other.

上述の様に構成する、請求項1〜2に記載した、本発明の衝撃吸収式ステアリングシャフトによれば、このステアリングシャフトを製造する際に、アウタシャフトの先端縁とインナシャフトの内周面との間にかじりが発生するのを防止し、加工の手間の増大や不良品の発生を抑えつつ、優れた衝撃エネルギ吸収性能を発揮できる衝撃吸収式ステアリングシャフトを組み立てて、前記ステアリングシャフトの製造コストの上昇を抑える事ができる。この理由は、前記インナシャフトの先端部のうち、先端縁寄り部分の外径を先端縁に向かう程小さくしている為、前記衝撃吸収式ステアリングシャフトを製造する際に、前記インナシャフトの先端縁と前記アウタシャフトの内周面との間でかじりが発生するのを防止できるからである。即ち、前記インナシャフトの先端縁部分は先端縁に向かう程外径が小さいので、このインナシャフトの先端部外周縁(尖鋭な端縁)と前記アウタシャフトの内周面とは当接しない(擦れ合わない)。前記インナシャフトの先端縁部分のうち、このアウタシャフトの内周面と当接する部分は、断面形状の曲率半径が大きい(或いはこのアウタシャフトの内周面に対する傾斜角が小さい)ので、前記インナシャフトの先端縁部分とこのアウタシャフトの内周面との当接圧を低くできる。この為、これら両シャフト同士を互いに近づく方向に軸方向に相対変位させる際に、前記インナシャフトの先端縁部分と前記アウタシャフトの内周面との間に作用する摩擦を小さく抑える事ができて、この先端縁部分がこの内周面に食い込む事を防止でき、前記かじりの発生を防止できる。   According to the shock absorbing steering shaft of the present invention configured as described above, when manufacturing the steering shaft, the outer edge of the outer shaft and the inner peripheral surface of the inner shaft The manufacturing cost of the steering shaft is assembled by assembling an impact-absorbing steering shaft that can exhibit excellent impact energy absorption performance while preventing the occurrence of galling between them and suppressing the increase in processing time and the occurrence of defective products The rise of the can be suppressed. The reason for this is that the outer diameter of the portion near the tip edge of the inner shaft tip portion is made smaller toward the tip edge, so that when the shock absorbing steering shaft is manufactured, the tip edge of the inner shaft This is because galling can be prevented from occurring between the outer peripheral shaft and the inner peripheral surface of the outer shaft. That is, since the outer edge of the inner shaft has a smaller outer diameter toward the front edge, the outer peripheral edge (sharp edge) of the inner shaft does not abut (rub against) the inner peripheral surface of the outer shaft. Do not fit). Of the tip edge portion of the inner shaft, the portion of the inner shaft that contacts the inner peripheral surface of the outer shaft has a large cross-sectional radius of curvature (or a small inclination angle with respect to the inner peripheral surface of the outer shaft). The abutting pressure between the tip edge portion and the inner peripheral surface of the outer shaft can be reduced. For this reason, when these two shafts are relatively displaced in the axial direction in the direction of approaching each other, the friction acting between the tip edge portion of the inner shaft and the inner peripheral surface of the outer shaft can be reduced. The tip edge portion can be prevented from biting into the inner peripheral surface, and the occurrence of the galling can be prevented.

又、請求項3〜4に記載した、本発明の衝撃吸収式ステアリングシャフトの製造方法によれば、上述した様な本発明の衝撃吸収式ステアリングシャフトを、工業的に能率良く製造する事ができる。   Further, according to the method for manufacturing the shock absorbing steering shaft of the present invention described in claims 3 to 4, the shock absorbing steering shaft of the present invention as described above can be manufactured industrially efficiently. .

本発明の実施の形態の第1例を示す、ステアリングシャフトの断面図。Sectional drawing of a steering shaft which shows the 1st example of embodiment of this invention. 同じく、図8と同様の図。Similarly, the same figure as FIG. 本発明の実施の形態の第2例を示す、インナシャフトを取り出して示す断面図。Sectional drawing which takes out and shows the inner shaft which shows the 2nd example of embodiment of this invention. 同じく第3例を示す、図2と同様の図。The figure similar to FIG. 2 which shows a 3rd example similarly. 同じく第4例を示す、図2と同様の図。The figure similar to FIG. 2 which shows the 4th example similarly. 従来から知られているステアリング装置の1例を、一部を切断した状態で示す側面図。The side view which shows one example of the steering device conventionally known in the state which cut | disconnected a part. 本発明の対象となる衝撃吸収式ステアリングシャフトの、従来構造の1例を示す断面図。Sectional drawing which shows one example of the conventional structure of the shock absorption type steering shaft used as the object of this invention. 従来構造の製造時に、インナシャフトの先端部とアウタシャフトの先端部とを係合させた状態を示す断面図。Sectional drawing which shows the state which engaged the front-end | tip part of the inner shaft, and the front-end | tip part of the outer shaft at the time of manufacture of a conventional structure. 図8のX−X断面図。XX sectional drawing of FIG. 1対の押圧片により、前記両先端部を径方向内方に塑性変形した状態で示す、図9と同様の図。FIG. 10 is a view similar to FIG. 9, showing a state where both the tip portions are plastically deformed radially inward by a pair of pressing pieces.

[実施の形態の第1例]
図1〜2は、全ての請求項に対応する、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、本発明の衝撃吸収式ステアリングシャフト及びその製造方法の特徴は、インナシャフト13aの先端縁と、アウタシャフト12aの内周面との間でかじりが発生するのを防止し、加工の手間の増大や不良品の発生を抑えつつ、優れた衝撃エネルギ吸収性能を発揮できる衝撃吸収式ステアリングシャフトを組み立てて、製造コストの上昇を抑える事ができる構造及びその製造方法を実現する点にある。その他の部分の構成及び作用は、前述の図7〜10に示した構造及びその製造方法を含め、従来から知られている衝撃吸収式ステアリングシャフト及びその製造方法と同様であるから、同等部分に関する図示並びに説明は、省略若しくは簡略にし、以下、本例の特徴部分を中心に説明する。
[First example of embodiment]
1-2 show a first example of an embodiment of the invention corresponding to all claims. In addition, including the present example, the features of the shock absorbing steering shaft and the manufacturing method thereof according to the present invention prevent galling between the tip edge of the inner shaft 13a and the inner peripheral surface of the outer shaft 12a. Assembling an impact-absorbing steering shaft that can exhibit excellent impact energy absorption performance while suppressing the increase in processing time and the occurrence of defective products, and realizing a structure and manufacturing method that can suppress an increase in manufacturing cost There is in point to do. Since the structure and operation of the other parts are the same as those of the conventionally known shock absorbing steering shaft and its manufacturing method, including the structure shown in FIGS. The illustration and description will be omitted or simplified, and the following description will focus on the features of this example.

本例の構造の場合、ステアリングシャフト3bを構成する、前記インナシャフト13aの後端部(図1〜2の右側)に、前端部(図1〜2の左側)よりも外径の大きい大径部16aを設けている。この様な大径部16aは、前記インナシャフト13aの前端部外周面に切削加工を施す事により形成する。若しくはこのインナシャフト13aが円管状であれば、前述した従来構造の場合と同様に、このインナシャフト13aの後端部を押し拡げる事により形成しても良い。或いは、前記インナシャフト13aを前記アウタシャフト12aの内径側に挿通可能であれば、前記大径部16aを設けず、前記インナシャフト13aの外径を軸方向全長に亙って同じとする事もできる。但し、この場合は、前記ステアリングシャフト3bの収縮荷重が過大になるのを防止すべく、前記インナシャフト13aの外周面に軸方向全長に亙って雄セレーション17を形成する。
又、前記アウタシャフト12aの前端部(図1〜2の左側)に、後端部(図1〜2の右側)よりも内径の小さい小径部14を設けている。この様な小径部14は、前述した従来構造の場合と同様に円管状である前記アウタシャフト12aの前端部に絞り加工を施す事により、若しくは後端部内周面に切削加工を施す事により形成する。或いは、前記インナシャフト13aを前記アウタシャフト12aの内径側に挿通可能であれば、前記小径部14を設けず、このアウタシャフト12aの内径を軸方向全長に亙って同じとする事もできる。但し、この場合は、前記ステアリングシャフト3bの収縮荷重が過大になるのを防止すべく、前記アウタシャフト12aの内周面に軸方向全長に亙って前記雄セレーション17と係合する、雌セレーション15を形成する。
図1〜2に示した本例の構造の場合、前記インナシャフト13aの前端部外周面に切削加工を施す事により後端部に大径部16aを、前記アウタシャフト12aの前端部に絞り加工を施す事により小径部14を、それぞれ設けている。
In the case of the structure of the present example, the rear end portion (right side in FIGS. 1 and 2) constituting the steering shaft 3b has a larger outer diameter than the front end portion (left side in FIGS. 1 and 2). A portion 16a is provided. Such a large diameter portion 16a is formed by cutting the outer peripheral surface of the front end portion of the inner shaft 13a. Alternatively, if the inner shaft 13a is circular, it may be formed by expanding the rear end portion of the inner shaft 13a as in the case of the conventional structure described above. Alternatively, if the inner shaft 13a can be inserted into the inner diameter side of the outer shaft 12a, the outer diameter of the inner shaft 13a may be the same over the entire axial length without providing the large diameter portion 16a. it can. However, in this case, male serrations 17 are formed on the outer peripheral surface of the inner shaft 13a over the entire length in the axial direction in order to prevent the shrinkage load of the steering shaft 3b from becoming excessive.
A small-diameter portion 14 having an inner diameter smaller than that of the rear end portion (right side in FIGS. 1 and 2) is provided at the front end portion (left side in FIGS. 1 and 2) of the outer shaft 12a. Such a small-diameter portion 14 is formed by drawing the front end portion of the outer shaft 12a which is tubular like the conventional structure described above, or by cutting the inner peripheral surface of the rear end portion. To do. Alternatively, if the inner shaft 13a can be inserted into the inner diameter side of the outer shaft 12a, the inner diameter of the outer shaft 12a can be made the same over the entire length in the axial direction without providing the small diameter portion 14. However, in this case, in order to prevent the shrinkage load of the steering shaft 3b from becoming excessive, a female serration that engages with the male serration 17 over the entire length in the axial direction on the inner peripheral surface of the outer shaft 12a. 15 is formed.
In the case of the structure of this example shown in FIGS. 1 and 2, a large-diameter portion 16a is drawn at the rear end by cutting the outer peripheral surface of the front end of the inner shaft 13a, and the front end of the outer shaft 12a is drawn. The small-diameter portions 14 are respectively provided by applying

更に、前記大径部16aの先端部外周縁(図1〜2の右側)に、断面形状が部分円弧状(R状)の面取り部21を設ける事により、前記大径部16aの先端部の外径が、この大径部16aの先端縁(図1〜2の右側)に向かう程小さくなる(漸減する)様にしている。尚、本例の場合、前記インナシャフト13aの大径部16aの先端部(図1〜2の右端部)に凹孔22を設け、後述する様に、1対の押圧片18、18によって前記小径部14の先端部及び前記大径部16aの先端部を径方向に塑性変形する際に、必要とされる押圧力が過度に大きくならない様にしている。   Furthermore, by providing a chamfered portion 21 having a partial arc shape (R shape) in cross-section at the outer peripheral edge (right side in FIGS. 1 and 2) of the distal end portion of the large diameter portion 16a, the distal end portion of the large diameter portion 16a is provided. The outer diameter is made smaller (decrease gradually) toward the tip edge (right side in FIGS. 1 and 2) of the large-diameter portion 16a. In the case of this example, a concave hole 22 is provided in the tip end portion (the right end portion in FIGS. 1 and 2) of the large-diameter portion 16a of the inner shaft 13a. When the distal end portion of the small-diameter portion 14 and the distal end portion of the large-diameter portion 16a are plastically deformed in the radial direction, the required pressing force is not excessively increased.

上述の様に構成する本例の衝撃吸収式ステアリングシャフトを製造する為に、先ず、図2に示す様に、前記大径部16aの先端部を前記小径部14の先端部に係合させる。そして、この小径部14の先端部の外周面を前記両押圧片18、18により径方向内方に押圧し、前述した従来構造の1例を示す図9→図10の場合と同様に、前記ステアリングシャフト3bの中心軸に直交する仮想平面に関する断面形状が楕円形となる様に、前記小径部14の先端部と前記大径部16aの先端部とを径方向に塑性変形させる。この時、前記両押圧片18、18を押圧する押圧力を調整しても良い。即ち、これら両押圧片18、18の端面同士の間の隙間20、20(図9参照)の厚さを、前記両先端部を塑性変形させた状態で正の値とし(隙間20、20を残し)、これら両先端部の変形量を調整する事もできる。又、前記両押圧片18、18の内側面で前記小径部14の先端部の外周面と当接する部分の形状は、前述した図9〜10に示す様な断面が円弧状の凹部19、19に限らず、前記小径部14の先端部の外周面の径方向反対位置を、互いに近付く方向に押圧できれば、平面や断面形状がV字形の面等とする事もできる。更に、断面円弧状とする場合でも、前記小径部14の先端部外周面の曲率半径との大小関係は、何れでも良い。又、前記面取り部21の基端部(大径側端部)は、前記両押圧片18、18により、アウタシャフト12aとインナシャフト13aとを押圧する際に、これら両押圧片18、18の軸方向中間部(これら両押圧片18、18の厚さ範囲内)の径方向内方に位置させている。前記両先端部同士の係合部を塑性変形したならば、次いで、前記アウタシャフト12aと前記インナシャフト13aとを軸方向に相対変位させて、前記小径部14の先端部を前記大径部16aの基端部に、この大径部16aの先端部にこの小径部14の基端部を、それぞれ圧入嵌合させる。又、これら小径部14の中間部と大径部16aの中間部とは、互いに緩く嵌合させる。   In order to manufacture the shock absorbing type steering shaft of the present example configured as described above, first, the distal end portion of the large diameter portion 16a is engaged with the distal end portion of the small diameter portion 14 as shown in FIG. And the outer peripheral surface of the front-end | tip part of this small diameter part 14 is pressed radially inward by the said both pressing pieces 18 and 18, similarly to the case of FIG. 9-> 10 which shows an example of the conventional structure mentioned above, The distal end portion of the small-diameter portion 14 and the distal end portion of the large-diameter portion 16a are plastically deformed in the radial direction so that a cross-sectional shape related to a virtual plane orthogonal to the central axis of the steering shaft 3b is an ellipse. At this time, the pressing force for pressing both the pressing pieces 18, 18 may be adjusted. That is, the thicknesses of the gaps 20 and 20 (see FIG. 9) between the end faces of the two pressing pieces 18 and 18 are set to positive values in a state where both the tip portions are plastically deformed (the gaps 20 and 20 are set to be the same). The amount of deformation of both the tip portions can be adjusted. The shape of the portion of the inner surface of the pressing pieces 18, 18 that contacts the outer peripheral surface of the tip of the small-diameter portion 14 is a concave portion 19, 19 having a circular cross section as shown in FIGS. Not limited to this, as long as the radially opposite positions of the outer peripheral surface of the distal end portion of the small-diameter portion 14 can be pressed toward each other, the plane or the cross-sectional shape can be a V-shaped surface or the like. Furthermore, even when the cross-sectional arc shape is used, the magnitude relationship with the curvature radius of the outer peripheral surface of the tip end portion of the small diameter portion 14 may be any. The base end portion (large-diameter side end portion) of the chamfered portion 21 is formed by the pressing pieces 18 and 18 when the outer shaft 12a and the inner shaft 13a are pressed by the pressing pieces 18 and 18. It is located inward in the radial direction of the axially intermediate portion (within the thickness range of both the pressing pieces 18, 18). If the engaging portion between the two tip portions is plastically deformed, then the outer shaft 12a and the inner shaft 13a are relatively displaced in the axial direction, and the tip portion of the small diameter portion 14 is moved to the large diameter portion 16a. The base end portion of the small-diameter portion 14 is press-fitted into the base end portion of the large-diameter portion 16a. Further, the intermediate portion of the small diameter portion 14 and the intermediate portion of the large diameter portion 16a are loosely fitted to each other.

上述の様に構成する本発明の衝撃吸収式ステアリングシャフト及びその製造方法によれば、前記ステアリングシャフト3bを製造する際に、前記インナシャフト13aの大径部16aの先端縁と前記アウタシャフト12aの小径部14の内周面との間にかじりが発生するのを防止し、前記ステアリングシャフト3bの製造コストの上昇を抑えつつ、優れた衝撃エネルギ吸収性能を発揮できる衝撃吸収式ステアリングシャフトを組み立てる事ができる。この理由は、前記大径部16aの先端部外周縁に断面形状が部分円弧状(R状)の面取り部21を設ける事で、この大径部16aの先端部のうち、先端縁部分の外径をこの大径部16aの先端縁に向かう程小さくしているからである。この様な構成を採用している為、前記ステアリングシャフト3bを製造する際に、前記アウタシャフト12aと前記インナシャフト13aとを互いに近づく方向に軸方向に相対変位させる際に、前記大径部16aの先端縁と前記小径部14の内周面とが強く擦れ合う事がない。即ち、この大径部16aの先端縁部分の外径が小さくなっている為、この大径部16aの先端部外周縁(尖鋭な端縁)と、前記小径部14の内周面とは当接しない。この大径部16aの先端縁部分のうち、この小径部14の内周面と当接する部分には、R状の面取り部21を設け、断面形状の曲率半径を大きくしているので、前記先端縁部分と前記小径部14の内周面との当接圧は低い。この為、前記両シャフト12a、13a同士を相対変位させる際に、前記大径部16aの先端縁部分と前記小径部14の内周面との間に作用する摩擦力を小さく抑える事ができて、この先端縁部分がこの内周面に食い込む事を防止でき、この内周面にかじりによる余肉部(むしれ)が発生するのを防止できる。   According to the shock absorbing type steering shaft of the present invention configured as described above and the manufacturing method thereof, when manufacturing the steering shaft 3b, the leading edge of the large diameter portion 16a of the inner shaft 13a and the outer shaft 12a Assembling an impact-absorbing steering shaft that prevents the occurrence of galling between the inner diameter surface of the small-diameter portion 14 and suppresses an increase in the manufacturing cost of the steering shaft 3b while exhibiting excellent impact energy absorption performance. Can do. The reason for this is that by providing a chamfered portion 21 having a partial arc shape (R shape) in the outer peripheral edge of the distal end portion of the large-diameter portion 16a, out of the distal end edge portion of the distal end portion of the large-diameter portion 16a. This is because the diameter is made smaller toward the leading edge of the large diameter portion 16a. Since such a configuration is adopted, when the steering shaft 3b is manufactured, when the outer shaft 12a and the inner shaft 13a are relatively displaced in the axial direction in a direction approaching each other, the large-diameter portion 16a. The tip edge of the small diameter portion and the inner peripheral surface of the small diameter portion 14 do not rub against each other. That is, since the outer diameter of the tip edge portion of the large diameter portion 16a is small, the outer peripheral edge (sharp edge) of the large diameter portion 16a and the inner peripheral surface of the small diameter portion 14 are not matched. Do not touch. Of the leading edge portion of the large-diameter portion 16a, an R-shaped chamfered portion 21 is provided at a portion that contacts the inner peripheral surface of the small-diameter portion 14, and the curvature radius of the cross-sectional shape is increased. The contact pressure between the edge portion and the inner peripheral surface of the small diameter portion 14 is low. Therefore, when the shafts 12a and 13a are relatively displaced, the frictional force acting between the tip edge portion of the large-diameter portion 16a and the inner peripheral surface of the small-diameter portion 14 can be reduced. The leading edge portion can be prevented from biting into the inner peripheral surface, and the occurrence of a surplus portion due to galling on the inner peripheral surface can be prevented.

尚、前記面取り部21の基端部(大径側端部)は、前記両シャフト12a、13a同士を塑性変形する際に、前記両押圧片18、18の軸方向中間部の径方向内方に位置させている為、前記大径部16aの先端縁部分で外径が小さくなっている部分を径方向内方に押圧する力を適切に制御(中間寄り部分よりも大きくなる事を防止)できる。この結果、前記大径部16aの先端縁と小径部14の内周面との擦れ合い部でかじりが生じる事を、より安定して防止できる。   The base end portion (large-diameter side end portion) of the chamfered portion 21 is radially inward of the intermediate portion in the axial direction of the pressing pieces 18 and 18 when the shafts 12a and 13a are plastically deformed. Therefore, the force of pressing the portion whose outer diameter is small at the tip edge portion of the large diameter portion 16a inward in the radial direction is appropriately controlled (preventing becoming larger than the intermediate portion) it can. As a result, it is possible to more stably prevent galling at the rubbing portion between the tip edge of the large diameter portion 16a and the inner peripheral surface of the small diameter portion 14.

[実施の形態の第2例]
図3は、請求項3〜4に対応する、本発明の実施の形態の第2例を示している。本例の場合には、インナシャフト13bの大径部16bの先端縁部分(図3の右側)に、この大径部16bの先端縁に向かう程この先端縁部分の外径が小さくなる様に、母線形状が直線状の(部分円すい面状の)テーパ面部23を設けている。このテーパ面部23のテーパ角θは、このテーパ面部23とアウタシャフト12aの小径部14(図1〜2、7〜10参照)の内周面との当接圧を小さくする為、60度以下とする事が望ましい。前記テーパ角θを60度よりも大きくすると、前記テーパ面部23の基端部と前記大径部16bの中間寄り部分との連続部の角度が小さく(150度未満に)なり、この連続部で、前記小径部14の内周面との当接圧が高くなる可能性がある。この結果、この連続部とこの小径部14の内周面との擦れ合い部でかじりが発生するのを防止できなくなる可能性がある。
[Second Example of Embodiment]
FIG. 3 shows a second example of an embodiment of the present invention corresponding to claims 3 to 4. In the case of this example, the outer diameter of the leading edge portion becomes smaller toward the leading edge of the large diameter portion 16b toward the leading edge portion (right side in FIG. 3) of the large diameter portion 16b of the inner shaft 13b. A tapered surface portion 23 having a straight line shape (partial conical surface shape) is provided. The taper angle θ of the taper surface portion 23 is 60 degrees or less in order to reduce the contact pressure between the taper surface portion 23 and the inner peripheral surface of the small diameter portion 14 (see FIGS. 1-2 and 7-10) of the outer shaft 12a. It is desirable that When the taper angle θ is larger than 60 degrees, the angle of the continuous portion between the proximal end portion of the tapered surface portion 23 and the intermediate portion of the large diameter portion 16b becomes small (less than 150 degrees). The contact pressure with the inner peripheral surface of the small diameter portion 14 may increase. As a result, it may not be possible to prevent galling at the rubbing portion between the continuous portion and the inner peripheral surface of the small diameter portion 14.

更に、本例の場合には、前記テーパ面部23の基端部(大径側端部)である、前記連続部に、断面形状が部分円弧状(R状)である、面取り部21aを設けている。本例の場合には、この連続部の角度を大きく(150度以上に)した事と、この連続部に面取り部21aを設けた事とにより、この連続部と前記小径部14の内周面との当接部の面圧を、より低く抑え、この当接部でのかじりの発生を、より効果的に抑えられる様にしている。尚、前記面取り部21aの基端部(大径側端部)は、前記両シャフト12a、13b同士を塑性変形する際に、1対の押圧片18、18の軸方向中間部(これら両押圧片18、18の厚さ範囲内)の径方向内方に位置させる。
その他の部分の構成及び作用は、上述した実施の形態の第1例と同様であるから、同等部分には同一符号を付して、重複する説明は省略する。
Furthermore, in the case of this example, a chamfered portion 21 a having a partial arc shape (R shape) is provided in the continuous portion, which is a base end portion (large diameter side end portion) of the tapered surface portion 23. ing. In the case of this example, the angle of the continuous portion is increased (150 degrees or more) and the chamfered portion 21a is provided in the continuous portion, so that the continuous portion and the inner peripheral surface of the small diameter portion 14 are provided. The surface pressure of the abutting portion is suppressed to be lower, and the occurrence of galling at the abutting portion can be more effectively suppressed. The base end portion (large-diameter side end portion) of the chamfered portion 21a is an intermediate portion in the axial direction of the pair of pressing pieces 18, 18 when the shafts 12a, 13b are plastically deformed. It is positioned radially inwardly within the thickness range of the pieces 18, 18.
Since the configuration and operation of the other parts are the same as those of the first example of the embodiment described above, the same parts are denoted by the same reference numerals, and redundant description is omitted.

[実施の形態の第3例]
図4も、請求項3〜4に対応する、本発明の実施の形態の第3例を示している。本例の場合には、インナシャフト13cを円管状とし、このインナシャフト13cの一端部(図4の右端部)に大径部16cを設けている。そして、この大径部16cの先端縁部分に絞り加工を施す事により、この大径部16cの先端縁部分の外径が先端縁(図4の右側)に向かう程小さくなる様に、絞り部24を設けている。この絞り部24の基端部(大径側端部)は、アウタシャフト12aと前記インナシャフト13cとを塑性変形する際に、1対の押圧片18、18の軸方向中間部(これら両押圧片18、18の厚さ範囲内)の径方向内方に位置させる。
その他の部分の構成及び作用は、前述した実施の形態の第1例と同様であるから、同等部分には同一符号を付して、重複する説明は省略する。
[Third example of embodiment]
FIG. 4 also shows a third example of the embodiment of the present invention corresponding to claims 3 to 4. In the case of this example, the inner shaft 13c is formed in a circular tube shape, and a large-diameter portion 16c is provided at one end portion (the right end portion in FIG. 4) of the inner shaft 13c. Then, by drawing the tip edge portion of the large diameter portion 16c, the drawn portion is reduced so that the outer diameter of the tip edge portion of the large diameter portion 16c decreases toward the tip edge (right side in FIG. 4). 24 is provided. When the outer shaft 12a and the inner shaft 13c are plastically deformed, the base end portion (large diameter side end portion) of the narrowed portion 24 is an axially intermediate portion of the pair of pressing pieces 18, 18 (both of these pressing portions). It is positioned radially inwardly within the thickness range of the pieces 18, 18.
Since the configuration and operation of the other parts are the same as those in the first example of the above-described embodiment, the same parts are denoted by the same reference numerals, and redundant description is omitted.

[実施の形態の第4例]
図5も、請求項3〜4に対応する、本発明の実施の形態の第4例を示している。本例の場合には、1対の押圧片18a、18aの先端面の軸方向両端縁に、断面形状が部分円弧状(R状)の面取りを施している。この為、大径部16aの先端部及び小径部14の先端部の変形量を、前記両押圧片18a、18aの軸方向両端縁の内径側で、同じく中間部よりも小さくできる。即ち、これら両端縁の内径側で、大径部16aの先端部と小径部14の先端部との嵌合強度を弱くしている為、ステアリングシャフトを製造する際に、インナシャフト13aとアウタシャフト12aとを軸方向に相対変位させても、前記大径部16aの先端縁と前記小径部14の内周面との擦れ合い部が強く擦れ合うのを、より効果的に防止できる。更に、この小径部14の先端縁と前記大径部16aの外周面との擦れ合い部に就いても、強く擦れ合うのを防止できる。この為、前記小径部14の先端縁と前記大径部16aの外周面との間でも、かじりが発生するのを防止でき、ステアリングシャフトの製造コストの上昇を抑えつつ、衝撃吸収性能を安定させる事を、前述の実施の形態の第1例と比較して、より有効に図れる。尚、この様な押圧片18a、18aは、本例に限らず、他の実施の形態に適用する事も可能である。
その他の部分の構成及び作用は、前述した実施の形態の第1例と同様であるから、同等部分には同一符号を付して、重複する説明は省略する。
[Fourth Example of Embodiment]
FIG. 5 also shows a fourth example of the embodiment of the invention corresponding to claims 3 to 4. In the case of this example, a chamfer having a partially arcuate (R-shaped) cross-sectional shape is applied to both end edges in the axial direction of the tip surfaces of the pair of pressing pieces 18a, 18a. For this reason, the amount of deformation of the distal end portion of the large-diameter portion 16a and the distal end portion of the small-diameter portion 14 can be made smaller than the intermediate portion on the inner diameter side of both end edges in the axial direction of the pressing pieces 18a, 18a. That is, since the fitting strength between the tip end portion of the large diameter portion 16a and the tip end portion of the small diameter portion 14 is weakened on the inner diameter side of these both end edges, the inner shaft 13a and the outer shaft are produced when the steering shaft is manufactured. Even if the 12a is relatively displaced in the axial direction, it is possible to more effectively prevent the rubbing portion between the tip edge of the large diameter portion 16a and the inner peripheral surface of the small diameter portion 14 from being strongly rubbed. Furthermore, even when the end edge of the small diameter portion 14 and the outer peripheral surface of the large diameter portion 16a are rubbed, it is possible to prevent strong rubbing. For this reason, it is possible to prevent the occurrence of galling between the tip edge of the small diameter portion 14 and the outer peripheral surface of the large diameter portion 16a, and to stabilize the shock absorbing performance while suppressing an increase in the manufacturing cost of the steering shaft. Compared to the first example of the above-described embodiment, this can be achieved more effectively. Such pressing pieces 18a and 18a are not limited to this example, and can be applied to other embodiments.
Since the configuration and operation of the other parts are the same as those in the first example of the above-described embodiment, the same parts are denoted by the same reference numerals, and redundant description is omitted.

1 車体
2 ステアリングコラム
3、3a〜3b ステアリングシャフト
4 ステアリングホイール
5a、5b 自在継手
6 中間シャフト
7 ステアリングギヤユニット
8 入力軸
9 タイロッド
10 電動モータ
11 アウタコラム
12、12a アウタシャフト
13、13a〜13c インナシャフト
14 小径部
15 雌セレーション
16、16a〜16c 大径部
17 雄セレーション
18、18a 押圧片
19 凹部
20 隙間
21、21a 面取り部
22 凹孔
23 テーパ面部
24 絞り部
DESCRIPTION OF SYMBOLS 1 Car body 2 Steering column 3, 3a-3b Steering shaft 4 Steering wheel 5a, 5b Universal joint 6 Intermediate shaft 7 Steering gear unit 8 Input shaft 9 Tie rod 10 Electric motor 11 Outer column 12, 12a Outer shaft 13, 13a-13c Inner shaft 14 Small-diameter portion 15 Female serration 16, 16a to 16c Large-diameter portion 17 Male serration 18, 18a Pressing piece 19 Recess 20 Clearance 21, 21a Chamfered portion 22 Recessed hole 23 Tapered surface portion 24 Restricted portion

この発明は、自動車のステアリング装置を構成する衝撃吸収式ステアリングシャフトの製造方法の改良に関する。具体的には、このステアリングシャフトを製造する際に、インナシャフトの先端縁とアウタシャフトの内周面との間にかじりが発生するのを防止して、前記ステアリングシャフトの製造コストの増大を抑えつつ、衝撃吸収性能を安定させられる製造方法を実現するものである。尚、本発明の対象となるステアリングシャフトには、ステアリングコラムの内側に支持されるものだけでなく、ステアリングコラムの前側に配置される中間シャフトも含む。 The present invention relates to an improvement in a manufacturing method of an impact absorption type steering shaft constituting an automobile steering device. Specifically, when manufacturing this steering shaft, the occurrence of galling between the inner edge of the inner shaft and the outer peripheral surface of the outer shaft is prevented, thereby suppressing an increase in the manufacturing cost of the steering shaft. On the other hand, a manufacturing method capable of stabilizing the shock absorbing performance is realized. Note that the steering shaft that is an object of the present invention includes not only a shaft supported on the inside of the steering column but also an intermediate shaft disposed on the front side of the steering column.

操舵輪(フォークリフト等の特殊車両を除き、通常は前輪)に舵角を付与する為のステアリング装置として、例えば図4に示す様な構造が、広く知られている。このステアリング装置は、車体1に支持された円筒状のステアリングコラム2の内径側にステアリングシャフト3を、回転可能に支持している。そして、このステアリングコラム2の後端開口よりも後方に突出した、前記ステアリングシャフト3の後端部分に、ステアリングホイール4を固定している。このステアリングホイール4を回転させると、この回転が、前記ステアリングシャフト3、自在継手5a、中間シャフト6、自在継手5bを介して、ステアリングギヤユニット7の入力軸8に伝達される。この入力軸8が回転すると、このステアリングギヤユニット7の両側に配置された1対のタイロッド9、9が押し引きされて左右1対の操舵輪に、前記ステアリングホイール4の操作量に応じた舵角を付与する。尚、図4に示した構造の場合、このステアリングホイール4の前後位置の調節を可能にすべく、前記ステアリングコラム2及び前記ステアリングシャフト3として、伸縮式のものを使用している。又、上述の様なステアリング装置に、電気モータ10を補助動力源として組み込んだ電動式パワーステアリング装置も、近年普及している。 For example, a structure as shown in FIG. 4 is widely known as a steering device for giving a steering angle to a steered wheel (usually a front wheel except for a special vehicle such as a forklift). In this steering device, a steering shaft 3 is rotatably supported on the inner diameter side of a cylindrical steering column 2 supported by a vehicle body 1. A steering wheel 4 is fixed to the rear end portion of the steering shaft 3 protruding rearward from the rear end opening of the steering column 2. When the steering wheel 4 is rotated, this rotation is transmitted to the input shaft 8 of the steering gear unit 7 via the steering shaft 3, the universal joint 5a, the intermediate shaft 6, and the universal joint 5b. When the input shaft 8 rotates, a pair of tie rods 9, 9 arranged on both sides of the steering gear unit 7 are pushed and pulled, and a steering wheel according to the operation amount of the steering wheel 4 is turned to a pair of left and right steering wheels. Give a corner. In the case of the structure shown in FIG. 4 , telescopic types are used as the steering column 2 and the steering shaft 3 in order to enable adjustment of the front-rear position of the steering wheel 4. In addition, in recent years, an electric power steering apparatus in which the electric motor 10 is incorporated as an auxiliary power source in the steering apparatus as described above has also become widespread.

前記ステアリングコラム2及び前記ステアリングシャフト3は、衝突事故の際に、衝撃エネルギを吸収しつつ、ステアリングホイール4を前方に変位させる構造としている。即ち、衝突事故の際には、自動車が他の自動車等にぶつかる一次衝突に続いて、運転者の身体がステアリングホイール4に衝突する二次衝突が発生する。この二次衝突の際に、運転者の身体に加わる衝撃を緩和して、運転者の保護を図る為に、前記ステアリングホイール4を支持したステアリングシャフト3を車体1に対して、二次衝突に伴う前方への衝撃荷重により前方に変位可能に支持する必要がある。この為に、前記ステアリングコラム2は、二次衝突の衝撃荷重により、アウタコラム11がこのステアリングコラム2の全長を、前記ステアリングシャフト3は、アウタシャフト12がこのステアリングシャフト3の全長を、それぞれ縮めながら前方に変位する事で、前記ステアリングホイール4に衝突した運転者の身体に大きな衝撃が加わる事を防止する。
上述の様な伸縮式のステアリングコラムを構成するアウタコラム及びインナコラム、並びに、ステアリングシャフトを構成するアウタシャフト及びインナシャフトの前後位置は、図示の構造とは逆であっても良い。上述の様な伸縮式のステアリングシャフトを製造する為の技術として、例えば特許文献1〜2に記載の技術がある。
The steering column 2 and the steering shaft 3 are configured to displace the steering wheel 4 while absorbing impact energy in the event of a collision. That is, in the event of a collision accident, a secondary collision in which the driver's body collides with the steering wheel 4 occurs following a primary collision in which the automobile collides with another automobile or the like. In order to alleviate the impact applied to the driver's body during the secondary collision and to protect the driver, the steering shaft 3 supporting the steering wheel 4 is subjected to the secondary collision with respect to the vehicle body 1. It is necessary to support it so that it can be displaced forward by a forward impact load. For this reason, the steering column 2 is contracted by the impact load of the secondary collision, the outer column 11 is shortened by the entire length of the steering column 2, and the steering shaft 3 is contracted by the outer shaft 12 by the total length of the steering shaft 3. However, a large impact is prevented from being applied to the driver's body colliding with the steering wheel 4 by being displaced forward.
The outer column and the inner column that constitute the telescopic steering column as described above, and the front and rear positions of the outer shaft and the inner shaft that constitute the steering shaft may be opposite to the illustrated structure. As a technique for manufacturing the telescopic steering shaft as described above, there are techniques described in Patent Documents 1 and 2, for example.

図5〜8は、このうちの特許文献1に記載されている、衝撃吸収式のステアリングシャフト及びその製造方法の従来例を示している。ステアリングシャフト3aは、アウタシャフト12aとインナシャフト13とを軸方向に相対変位可能に係合させ、二次衝突時に、軸方向に加わる衝撃荷重により全長が縮まる様に構成している。
前記アウタシャフト12aは、全体を円管状とし、一端部(図5〜6の左端部)に絞り加工を施す事で、この一端部に小径部14を形成している。この小径部14の内周面には、雌セレーション15を形成している。又、前記インナシャフト13も、全体を円管状とし、一端部(図5〜6の右端部)を押し拡げる事で、この一端部に大径部16を形成している。この大径部16の外周面には、前記雌セレーション15と係合する雄セレーション17を形成している。
5 to 8 show a conventional example of an impact absorbing steering shaft and a manufacturing method thereof described in Patent Document 1 among them. The steering shaft 3a is configured such that the outer shaft 12a and the inner shaft 13 are engaged with each other so as to be relatively displaceable in the axial direction, and the total length is shortened by an impact load applied in the axial direction at the time of a secondary collision.
The outer shaft 12a is formed into a tubular shape as a whole, and a small-diameter portion 14 is formed at one end portion by drawing one end portion (left end portion in FIGS. 5 to 6 ). A female serration 15 is formed on the inner peripheral surface of the small diameter portion 14. The inner shaft 13 is also formed in a circular tube shape as a whole, and a large-diameter portion 16 is formed at one end portion by expanding one end portion (the right end portion in FIGS. 5 to 6 ). A male serration 17 that engages with the female serration 15 is formed on the outer peripheral surface of the large diameter portion 16.

この様なアウタシャフト12aとインナシャフト13とを組み合わせて、図5に示す様なステアリングシャフト3aを製造する場合には、先ず、図6に示す様に、前記雌セレーション15と前記雄セレーション17とを、前記小径部14の先端部(図6の左端部)と前記大径部16の先端部(図6の右端部)とで互いに係合させる。
そして、前記両セレーション15、17同士を互いに係合させた状態のまま、前記小径部14の先端部の外周面を径方向内方に押圧する。即ち、この小径部14の先端部及び前記大径部16の先端部の周囲に1対の押圧片18、18を配置し、これら両押圧片18、18を互いに近づけ合う事で、前記小径部14の先端部の外周面を強く押圧する。これら両押圧片18、18の内側面でこの小径部14の先端部の外周面と当接する部分には、この外周面に当接する部分の断面形状が円弧状である、凹部19、19を形成している。
When the steering shaft 3a as shown in FIG. 5 is manufactured by combining such an outer shaft 12a and the inner shaft 13, first, as shown in FIG. 6 , the female serration 15 and the male serration 17 Are engaged with each other at the distal end portion (left end portion in FIG. 6 ) of the small diameter portion 14 and the distal end portion (right end portion in FIG. 6 ) of the large diameter portion 16.
And the outer peripheral surface of the front-end | tip part of the said small diameter part 14 is pressed to radial direction inward with the said both serrations 15 and 17 being mutually engaged. That is, a pair of pressing pieces 18, 18 are arranged around the distal end portion of the small diameter portion 14 and the distal end portion of the large diameter portion 16, and the two small pressing portions 18, 18 are brought close to each other, whereby the small diameter portion 14 strongly presses the outer peripheral surface of the tip portion. On the inner side surfaces of these pressing pieces 18, 18 are formed recesses 19, 19 in which the cross-sectional shape of the portion contacting the outer peripheral surface is arcuate in the portion contacting the outer peripheral surface of the tip of the small diameter portion 14 doing.

図7に示す様に、これら両凹部19、19を前記小径部14の先端部の外周面に軽く当接させた状態で、前記両押圧片18、18の端面同士の間に、厚さがtの隙間20、20が形成される。この状態から、これら両押圧片18、18を、図示しない押圧装置により、互いに近づく方向に強く押圧する。そして、図8に示す様に、前記両隙間20、20の厚さが0となるまで、前記両押圧片18、18同士を互いに近づけ、前記小径部14の先端部の断面形状を、図8に示す様な楕円形に塑性変形させる。同時に、この小径部14の先端部に挿入された大径部16の先端部も、前記両セレーション15、17を介して押圧し、この大径部16の先端部の断面形状も、図8に示す様な楕円形に塑性変形させる。 As shown in FIG. 7 , the thickness between the end faces of the pressing pieces 18, 18 is set in a state where both the recesses 19, 19 are lightly brought into contact with the outer peripheral surface of the distal end portion of the small diameter portion 14. T gaps 20 and 20 are formed. From this state, both the pressing pieces 18, 18 are strongly pressed in a direction approaching each other by a pressing device (not shown). Then, as shown in FIG. 8 , the pressing pieces 18, 18 are brought close to each other until the thickness of the gaps 20, 20 becomes 0, and the sectional shape of the distal end portion of the small diameter portion 14 is shown in FIG. 8. It is plastically deformed into an oval shape as shown in. At the same time, the distal end portion of the large diameter portion 16 inserted into the distal end portion of the small diameter portion 14 is also pressed through the both serrations 15 and 17, and the sectional shape of the distal end portion of the large diameter portion 16 is also shown in FIG. Plastically deform into an elliptical shape as shown.

この様にして、前記小径部14の先端部及び前記大径部16の先端部を径方向内方に押圧し、これら両先端部の断面形状を楕円形に塑性変形させたならば、次いで、前記アウタシャフト12aと前記インナシャフト13とを互いに近づく方向に軸方向に相対変位させる。即ち、前記両押圧片18、18から前記アウタシャフト12aと前記インナシャフト13とを取り出した後、このアウタシャフト12aを図6の左方に、このインナシャフト13を同じく右方に、相手部材に対して相対変位させる。そして、図5に示す様に、前記小径部14の先端部を前記大径部16の基端部に圧入嵌合すると共に、この大径部16の先端部をこの小径部14の基端部に圧入嵌合させる。前記両押圧片18、18により塑性変形させられていない、この小径部14の中間部と前記大径部16の中間部とは互いに緩く係合させる。
尚、上述の様な衝撃吸収式ステアリングシャフトを構成するインナシャフト13は、アウタシャフト12aよりも外径が小さいので、強度を確保する為、S35C等硬度の高い炭素鋼により形成する事が多い。或いは、STKM12B等の炭素鋼鋼管により形成する事もできるが、この場合は強度を確保する為、径方向の厚さを厚くする。
In this way, if the distal end portion of the small diameter portion 14 and the distal end portion of the large diameter portion 16 are pressed radially inward, and the cross-sectional shape of both the distal end portions is plastically deformed into an elliptical shape, then, The outer shaft 12a and the inner shaft 13 are relatively displaced in the axial direction so as to approach each other. That is, after the outer shaft 12a and the inner shaft 13 are taken out from the pressing pieces 18, 18, the outer shaft 12a is moved to the left in FIG. The relative displacement is made. Then, as shown in FIG. 5 , the distal end portion of the small diameter portion 14 is press-fitted into the proximal end portion of the large diameter portion 16, and the distal end portion of the large diameter portion 16 is replaced with the proximal end portion of the small diameter portion 14. Press-fit into. The intermediate portion of the small diameter portion 14 and the intermediate portion of the large diameter portion 16 that are not plastically deformed by the two pressing pieces 18 and 18 are loosely engaged with each other.
Since the inner shaft 13 constituting the shock absorbing steering shaft as described above has a smaller outer diameter than the outer shaft 12a, it is often formed of carbon steel having a high hardness such as S35C in order to ensure strength. Alternatively, it can be formed of a carbon steel pipe such as STKM12B. In this case, the radial thickness is increased in order to ensure strength.

以上の説明は、後端部分にステアリングホイール4(図4参照)を固定するステアリングシャフト3に就いて行ったが、ステアリング装置の前側部分に配置される中間シャフト6も同様にして、軸方向に収縮可能に構成する場合がある。この様な収縮式(衝撃吸収式)の中間シャフト6は、自動車が他の自動車等にぶつかる一次衝突の際に、この一次衝突に伴う衝撃荷重よりその全長を縮める事で、前記ステアリングホイール4が運転者側に突き上げられるのを防止し、運転者の保護を図る。尚、前記中間シャフト6は、運転者の操作によって前記ステアリングホイール4から前記ステアリングシャフト3に付与されるトルクに加え、補助動力源である電動モータ10の出力トルクを伝達する。この為、上述の様な衝撃吸収式ステアリングシャフトを、前記中間シャフト6に適用する場合、前記アウタシャフト12aとインナシャフト13との係合部の保持力(嵌合強度)を大きくし、耐久性を高くする必要がある。この結果、前記大径部16の先端部外周縁(尖鋭な端縁)と、前記小径部14の内周面との当接圧が高くなり、上述の様な衝撃吸収式ステアリングシャフトの製造方法を実施する場合に於いて、前記アウタシャフト12aとインナシャフト13とを互いに近づく方向に軸方向に相対変位させる際に、前記大径部16の先端部外周縁でかじりが発生し易い。即ち、この相対変位の際、断面形状が楕円形であるこの大径部16の先端部外周縁の長径部分と、断面形状が円形である前記小径部14の内周面とが強く擦れ合って、この先端部外周縁がこの小径部14の内周面に食い込む(かじる)。この様にして発生したかじりを放置すると、衝突事故の際のエネルギ吸収性能が不安定になる可能性がある。そこでこのエネルギ吸収性能を安定させる為に、かじりにより生じた余肉部分(むしれ部分)を切削等により除去する手間が必要になる。又、かじりの程度によっては、完成後の衝撃吸収式ステアリングシャフトを、不良品として廃棄しなければならなくなり、加工の手間の増大や歩留りの悪化により、製造コストが上昇する為、改良が望まれる。特に、前記中間シャフト6の場合、前述した様に、保持力確保の為に嵌合部の当接圧を高くする為、改良する必要性が大きい。 Although the above description has been given with respect to the steering shaft 3 that fixes the steering wheel 4 (see FIG. 4 ) to the rear end portion, the intermediate shaft 6 disposed in the front side portion of the steering device is similarly axially arranged. It may be configured to be shrinkable. Such a contraction type (shock absorption type) intermediate shaft 6 reduces the total length of the steering wheel 4 from the impact load associated with the primary collision at the time of the primary collision when the automobile collides with another automobile or the like. The driver is prevented from being pushed up to protect the driver. The intermediate shaft 6 transmits the output torque of the electric motor 10 as an auxiliary power source in addition to the torque applied from the steering wheel 4 to the steering shaft 3 by the operation of the driver. For this reason, when the shock absorbing steering shaft as described above is applied to the intermediate shaft 6, the holding force (fitting strength) of the engaging portion between the outer shaft 12a and the inner shaft 13 is increased, and the durability is improved. Need to be high. As a result, the contact pressure between the outer peripheral edge (sharp edge) of the distal end portion of the large-diameter portion 16 and the inner peripheral surface of the small-diameter portion 14 increases, and the method for manufacturing the shock absorbing steering shaft as described above When the outer shaft 12a and the inner shaft 13 are relatively displaced in the axial direction in the direction approaching each other, galling is likely to occur at the outer peripheral edge of the distal end portion of the large diameter portion 16. That is, at the time of this relative displacement, the long diameter portion of the outer peripheral edge of the distal end portion of the large diameter portion 16 having an elliptical cross-sectional shape and the inner peripheral surface of the small diameter portion 14 having a circular cross sectional shape are strongly rubbed. The outer peripheral edge of the tip portion bites into the inner peripheral surface of the small diameter portion 14. If the galling generated in this way is left unattended, the energy absorption performance in the event of a collision may become unstable. Therefore, in order to stabilize the energy absorption performance, it is necessary to remove a surplus portion (peeling portion) generated by galling by cutting or the like. Also, depending on the degree of galling, the completed shock absorbing steering shaft must be discarded as a defective product, which increases manufacturing costs due to increased processing effort and yield, and improvements are desired. . In particular, in the case of the intermediate shaft 6, as described above, there is a great need for improvement in order to increase the contact pressure of the fitting portion in order to secure the holding force.

特許第3168841号公報Japanese Patent No. 3168841 特許第3716590号公報Japanese Patent No. 3716590

本発明は、上述の様な事情に鑑み、アウタシャフトとインナシャフトとを、二次衝突時に加わる衝撃荷重に伴い、これら両シャフト同士が軸方向に相対変位可能に結合して成る衝撃吸収式ステアリングシャフトを製造する際に、前記インナシャフトの先端部外周縁と前記アウタシャフトの内周面との間にかじりが発生するのを防止し、加工の手間の増大や不良品の発生を抑えつつ、エネルギ吸収性能の安定した衝撃吸収式ステアリングシャフトを得られる様にして、製造コストの上昇を抑える事ができる製造方法を実現すべく発明したものである。 In view of the circumstances as described above, the present invention is an impact-absorbing steering system in which an outer shaft and an inner shaft are coupled to each other so as to be capable of relative displacement in the axial direction in accordance with an impact load applied during a secondary collision. When manufacturing the shaft, it prevents the occurrence of galling between the outer peripheral edge of the tip of the inner shaft and the inner peripheral surface of the outer shaft, while suppressing the increase in processing and the occurrence of defective products, The invention was invented to realize a manufacturing method capable of suppressing an increase in manufacturing cost so as to obtain an impact absorbing steering shaft having stable energy absorbing performance.

本発明の衝撃吸収式ステアリングシャフトの製造方法は、アウタシャフトの先端部とインナシャフトの先端部とを係合させた状態で、このアウタシャフトの先端部の外周面を1対の押圧片によって径方向内方に(径方向反対位置を互いに近付く方向に)押圧し、このアウタシャフトの先端部及び前記インナシャフトの先端部を径方向に(押圧方向が短径でこれと直角方向が長径となる、断面楕円形に)塑性変形させる。次いで、前記両シャフト同士を互いに近づく方向に軸方向に相対変位させる。そして、前記アウタシャフトの先端部を前記インナシャフトの中間部に、このインナシャフトの先端部をこのアウタシャフトの中間部に、それぞれ圧入嵌合させる。このアウタシャフトの先端部と中間部との間部分と、前記インナシャフトの先端部と中間部との間部分とは、互いに緩く係合させる。
特に、本発明の衝撃吸収式ステアリングシャフトの製造方法に於いては、前記インナシャフトとして、このインナシャフトの先端縁部分に、先端縁に向かう程この先端縁部分の外径が小さくなった、テーパ面部を設け、このテーパ面部の基端部と前記インナシャフトの中間寄り部分との連続部に、断面形状が部分円弧状である、面取り部を設けているものを使用する。そして、前記アウタシャフトの先端部及び前記インナシャフトの先端部を径方向に塑性変形させる際に、前記面取り部の基端部を前記両押圧片の軸方向中間部の径方向内方に位置させる。
In the manufacturing method of the shock absorbing steering shaft of the present invention , the outer peripheral surface of the outer shaft front end is engaged with a pair of pressing pieces while the outer shaft front end and the inner shaft front end are engaged. The inner shaft is pressed inward (in the direction in which the opposite positions in the radial direction approach each other), and the distal end portion of the outer shaft and the distal end portion of the inner shaft are in the radial direction (the pressing direction is the short diameter and the perpendicular direction is the long diameter). Plastic deformation). Next, the shafts are relatively displaced in the axial direction so as to approach each other. And the front-end | tip part of the said outer shaft is press-fitted and fitted to the intermediate part of the said inner shaft, and the front-end | tip part of this inner shaft is each press-fitted to the intermediate part of this outer shaft. A portion between the front end portion and the intermediate portion of the outer shaft and a portion between the front end portion and the intermediate portion of the inner shaft are loosely engaged with each other.
In particular, in the shock absorbing type steering shaft manufacturing method of the present invention, as the inner shaft , a taper in which the outer diameter of the tip edge portion becomes smaller toward the tip edge portion toward the tip edge portion of the inner shaft. A surface portion is provided, and a chamfered portion having a partial arc shape in cross section is used at a continuous portion between the proximal end portion of the tapered surface portion and the intermediate portion of the inner shaft . When the distal end portion of the outer shaft and the distal end portion of the inner shaft are plastically deformed in the radial direction, the base end portion of the chamfered portion is positioned radially inward of the axial intermediate portion of the two pressing pieces. .

上述の様な本発明の衝撃吸収式ステアリングシャフトの製造方法を実施する場合に、例えば請求項に記載した発明の様に、前記アウタシャフトとして、一端部に少なくとも内径が小さい小径部を設けたものを、前記インナシャフトとして、一端部に少なくとも外径が大きい大径部を設け、この大径部の先端部のうち、少なくとも先端縁寄り部分の外径が先端縁に向かう程小さいものを、それぞれ使用する。そして、前記小径部の先端部と前記大径部の先端部とを係合させた状態で、この小径部の先端部の外周面を径方向内方に(径方向反対位置を互いに近付く方向に)押圧し、この小径部の先端部及び前記大径部の先端部を径方向に(押圧方向が短径でこれと直角方向が長径となる、断面楕円形に)塑性変形させる。次いで、前記両シャフト同士を互いに近づく方向に軸方向に相対変位させ、前記小径部の先端部を前記大径部の基端部に、この大径部の先端部をこの小径部の基端部に、それぞれ圧入嵌合させ、この小径部の中間部とこの大径部の中間部とを互いに緩く係合させる。 When the shock absorbing steering shaft manufacturing method of the present invention as described above is carried out, for example, as in the invention described in claim 2 , at least one small diameter portion having a small inner diameter is provided at one end portion as the outer shaft. As the inner shaft, at least one large-diameter portion having a large outer diameter is provided at one end portion, and at least the outer diameter of the portion close to the tip edge of the tip portion of the large-diameter portion is small toward the tip edge. Use each one. Then, with the tip portion of the small diameter portion and the tip portion of the large diameter portion engaged, the outer peripheral surface of the tip portion of the small diameter portion is directed radially inward (in the direction in which the opposite radial positions approach each other). ) Press and plastically deform the tip of the small-diameter portion and the tip of the large-diameter portion in the radial direction (in a cross-sectional ellipse in which the pressing direction is the short diameter and the direction perpendicular thereto is the long diameter). Next, the shafts are relatively displaced in the axial direction so as to approach each other, the distal end portion of the small diameter portion is the proximal end portion of the large diameter portion, and the distal end portion of the large diameter portion is the proximal end portion of the small diameter portion The intermediate portion of the small diameter portion and the intermediate portion of the large diameter portion are loosely engaged with each other.

上述の様に構成する、本発明の衝撃吸収式ステアリングシャフトの製造方法によれば、このステアリングシャフトを製造する際に、インナシャフトの先端縁とアウタシャフトの内周面との間にかじりが発生するのを防止し、加工の手間の増大や不良品の発生を抑えつつ、優れた衝撃エネルギ吸収性能を発揮できる衝撃吸収式ステアリングシャフトを組み立てて、前記ステアリングシャフトの製造コストの上昇を抑える事ができて、衝撃吸収式ステアリングシャフトを、工業的に能率良く製造する事ができる。この理由は、前記インナシャフトの先端縁部分に、先端縁に向かう程この先端縁部分の外径が小さくなったテーパ面部を設けている為、前記衝撃吸収式ステアリングシャフトを製造する際に、前記インナシャフトの先端縁と前記アウタシャフトの内周面との間でかじりが発生するのを防止できるからである。即ち、前記インナシャフトの先端縁部分(テーパ面部)は先端縁に向かう程外径が小さいので、このインナシャフトの先端部外周縁(尖鋭な端縁)と前記アウタシャフトの内周面とは当接しない(擦れ合わない)。更に本発明の場合、前記テーパ面部の基端部と前記インナシャフトの中間寄り部分との連続部に、断面形状が部分円弧状である、面取り部を設けている。この為、この連続部と前記アウタシャフトの内周面との当接部の面圧をより低く抑え、これら両シャフト同士を互いに近づく方向に軸方向に相対変位させる際に、前記当接部でのかじりの発生を、より効果的に抑えられる様にしている。特に、本発明の場合には、前記アウタシャフトの先端部及び前記インナシャフトの先端部を径方向に塑性変形させる際に、前記面取り部の基端部を前記両押圧片の軸方向中間部の径方向内方に位置させている。この為、前記インナシャフトの先端縁部分に設けたテーパ面部及び面取り部を径方向内方に押圧する力を適切に制御(中間寄り部分よりも大きくなる事を防止)できる。 According to the shock absorbing steering shaft manufacturing method of the present invention configured as described above, galling occurs between the tip edge of the inner shaft and the inner peripheral surface of the outer shaft when the steering shaft is manufactured. It is possible to assemble an impact-absorbing steering shaft that can exhibit excellent impact energy absorption performance while suppressing the increase in processing effort and the occurrence of defective products, and suppressing the increase in the manufacturing cost of the steering shaft Thus , the shock absorbing steering shaft can be manufactured industrially efficiently . The reason for this is that a taper surface portion whose outer diameter is reduced toward the tip edge is provided at the tip edge portion of the inner shaft. This is because galling can be prevented between the tip edge of the inner shaft and the inner peripheral surface of the outer shaft. That is, since the outer diameter of the tip edge portion (tapered surface portion) of the inner shaft decreases toward the tip edge, the outer peripheral edge (sharp edge) of the inner shaft and the inner peripheral surface of the outer shaft are in contact with each other. Do not touch (do not rub). Further, in the case of the present invention, a chamfered portion whose cross-sectional shape is a partial arc shape is provided in a continuous portion between the proximal end portion of the tapered surface portion and the intermediate portion of the inner shaft. For this reason, when the surface pressure of the contact portion between the continuous portion and the inner peripheral surface of the outer shaft is kept low, and the shafts are relatively displaced in the axial direction in the direction of approaching each other, the contact portion The occurrence of galling is made more effective. In particular, in the case of the present invention, when the distal end portion of the outer shaft and the distal end portion of the inner shaft are plastically deformed in the radial direction, the base end portion of the chamfered portion is placed between the axial intermediate portions of the two pressing pieces. It is located radially inward. For this reason, the force which presses the taper surface part and chamfering part provided in the front-end | tip edge part of the said inner shaft to radial direction inward can be controlled appropriately (it can prevent becoming larger than an intermediate part).

本発明に関する参考例の第1例を示す、ステアリングシャフトの断面図。Sectional drawing of a steering shaft which shows the 1st example of the reference example regarding this invention. 同じく、図6と同様の図。Similarly, the same figure as FIG. 本発明の実施の形態の1例を示す、インナシャフトを取り出して示す断面図。Sectional drawing which takes out and shows the inner shaft which shows one example of embodiment of this invention. 従来から知られているステアリング装置の1例を、一部を切断した状態で示す側面図。The side view which shows one example of the steering device conventionally known in the state which cut | disconnected a part. 本発明の対象となる衝撃吸収式ステアリングシャフトの、従来構造の1例を示す断面図。Sectional drawing which shows one example of the conventional structure of the shock absorption type steering shaft used as the object of this invention. 従来構造の製造時に、インナシャフトの先端部とアウタシャフトの先端部とを係合させた状態を示す断面図。Sectional drawing which shows the state which engaged the front-end | tip part of the inner shaft, and the front-end | tip part of the outer shaft at the time of manufacture of a conventional structure. 図6のX−X断面図。XX sectional drawing of FIG. 1対の押圧片により、前記両先端部を径方向内方に塑性変形した状態で示す、図7と同様の図。FIG. 8 is a view similar to FIG. 7, showing a state in which both the tip portions are plastically deformed radially inward by a pair of pressing pieces.

参考例の第1例]
図1〜2は、本発明に関する参考例の1例を示している。尚、本参考例を含めて、本発明の衝撃吸収式ステアリングシャフトの製造方法の特徴は、インナシャフト13aの先端縁と、アウタシャフト12aの内周面との間でかじりが発生するのを防止し、加工の手間の増大や不良品の発生を抑えつつ、優れた衝撃エネルギ吸収性能を発揮できる衝撃吸収式ステアリングシャフトを組み立てて、製造コストの上昇を抑える事ができる製造方法を実現する点にある。その他の部分の構成及び作用は、前述の図5〜8に示した構造及びその製造方法を含め、従来から知られている衝撃吸収式ステアリングシャフト及びその製造方法と同様であるから、同等部分に関する図示並びに説明は、省略若しくは簡略にし、以下、本参考例の特徴部分を中心に説明する。
[First example of reference example ]
1 and 2 show an example of a reference example related to the present invention . In addition, including the present reference example , the shock absorbing type steering shaft manufacturing method according to the present invention is characterized in that galling is prevented between the tip edge of the inner shaft 13a and the inner peripheral surface of the outer shaft 12a. In order to realize a manufacturing method that can suppress an increase in manufacturing cost by assembling an impact absorbing steering shaft that can exhibit excellent impact energy absorption performance while suppressing an increase in processing time and occurrence of defective products is there. The structure and operation of the other parts are the same as those of the conventionally known shock absorbing steering shaft and its manufacturing method, including the structure shown in FIGS. The illustration and description will be omitted or simplified, and the following description will focus on the features of this reference example .

本参考例の構造の場合、ステアリングシャフト3bを構成する、前記インナシャフト13aの後端部(図1〜2の右側)に、前端部(図1〜2の左側)よりも外径の大きい大径部16aを設けている。この様な大径部16aは、前記インナシャフト13aの前端部外周面に切削加工を施す事により形成する。若しくはこのインナシャフト13aが円管状であれば、前述した従来構造の場合と同様に、このインナシャフト13aの後端部を押し拡げる事により形成しても良い。或いは、前記インナシャフト13aを前記アウタシャフト12aの内径側に挿通可能であれば、前記大径部16aを設けず、前記インナシャフト13aの外径を軸方向全長に亙って同じとする事もできる。但し、この場合は、前記ステアリングシャフト3bの収縮荷重が過大になるのを防止すべく、前記インナシャフト13aの外周面に軸方向全長に亙って雄セレーション17を形成する。
又、前記アウタシャフト12aの前端部(図1〜2の左側)に、後端部(図1〜2の右側)よりも内径の小さい小径部14を設けている。この様な小径部14は、前述した従来構造の場合と同様に円管状である前記アウタシャフト12aの前端部に絞り加工を施す事により、若しくは後端部内周面に切削加工を施す事により形成する。或いは、前記インナシャフト13aを前記アウタシャフト12aの内径側に挿通可能であれば、前記小径部14を設けず、このアウタシャフト12aの内径を軸方向全長に亙って同じとする事もできる。但し、この場合は、前記ステアリングシャフト3bの収縮荷重が過大になるのを防止すべく、前記アウタシャフト12aの内周面に軸方向全長に亙って前記雄セレーション17と係合する、雌セレーション15を形成する。
図1〜2に示した本参考例の構造の場合、前記インナシャフト13aの前端部外周面に切削加工を施す事により後端部に大径部16aを、前記アウタシャフト12aの前端部に絞り加工を施す事により小径部14を、それぞれ設けている。
In the case of the structure of this reference example , the rear end portion (right side in FIGS. 1 and 2) constituting the steering shaft 3b has a larger outer diameter than the front end portion (left side in FIGS. 1 and 2). A diameter portion 16a is provided. Such a large diameter portion 16a is formed by cutting the outer peripheral surface of the front end portion of the inner shaft 13a. Alternatively, if the inner shaft 13a is circular, it may be formed by expanding the rear end portion of the inner shaft 13a as in the case of the conventional structure described above. Alternatively, if the inner shaft 13a can be inserted into the inner diameter side of the outer shaft 12a, the outer diameter of the inner shaft 13a may be the same over the entire axial length without providing the large diameter portion 16a. it can. However, in this case, male serrations 17 are formed on the outer peripheral surface of the inner shaft 13a over the entire length in the axial direction in order to prevent the shrinkage load of the steering shaft 3b from becoming excessive.
A small-diameter portion 14 having an inner diameter smaller than that of the rear end portion (right side in FIGS. 1 and 2) is provided at the front end portion (left side in FIGS. 1 and 2) of the outer shaft 12a. Such a small-diameter portion 14 is formed by drawing the front end portion of the outer shaft 12a which is tubular like the conventional structure described above, or by cutting the inner peripheral surface of the rear end portion. To do. Alternatively, if the inner shaft 13a can be inserted into the inner diameter side of the outer shaft 12a, the inner diameter of the outer shaft 12a can be made the same over the entire length in the axial direction without providing the small diameter portion 14. However, in this case, in order to prevent the shrinkage load of the steering shaft 3b from becoming excessive, a female serration that engages with the male serration 17 over the entire length in the axial direction on the inner peripheral surface of the outer shaft 12a. 15 is formed.
In the case of the structure of this reference example shown in FIGS. 1 and 2, by cutting the outer peripheral surface of the front end portion of the inner shaft 13a, the large-diameter portion 16a is drawn at the rear end portion, and the front end portion of the outer shaft 12a is narrowed down. Each of the small diameter portions 14 is provided by processing.

更に、前記大径部16aの先端部外周縁(図1〜2の右側)に、断面形状が部分円弧状(R状)の面取り部21を設ける事により、前記大径部16aの先端部の外径が、この大径部16aの先端縁(図1〜2の右側)に向かう程小さくなる(漸減する)様にしている。尚、本参考例の場合、前記インナシャフト13aの大径部16aの先端部(図1〜2の右端部)に凹孔22を設け、後述する様に、1対の押圧片18、18によって前記小径部14の先端部及び前記大径部16aの先端部を径方向に塑性変形する際に、必要とされる押圧力が過度に大きくならない様にしている。 Furthermore, by providing a chamfered portion 21 having a partial arc shape (R shape) in cross-section at the outer peripheral edge (right side in FIGS. 1 and 2) of the distal end portion of the large diameter portion 16a, the distal end portion of the large diameter portion 16a is provided. The outer diameter is made smaller (decrease gradually) toward the tip edge (right side in FIGS. 1 and 2) of the large-diameter portion 16a. In the case of this reference example , a concave hole 22 is provided at the tip end portion (the right end portion in FIGS. 1 and 2) of the large diameter portion 16a of the inner shaft 13a, and as will be described later, When the distal end portion of the small-diameter portion 14 and the distal end portion of the large-diameter portion 16a are plastically deformed in the radial direction, the required pressing force is not excessively increased.

上述の様に構成する本参考例の衝撃吸収式ステアリングシャフトを製造する為に、先ず、図2に示す様に、前記大径部16aの先端部を前記小径部14の先端部に係合させる。そして、この小径部14の先端部の外周面を前記両押圧片18、18により径方向内方に押圧し、前述した従来構造の1例を示す図7→図8の場合と同様に、前記ステアリングシャフト3bの中心軸に直交する仮想平面に関する断面形状が楕円形となる様に、前記小径部14の先端部と前記大径部16aの先端部とを径方向に塑性変形させる。この時、前記両押圧片18、18を押圧する押圧力を調整しても良い。即ち、これら両押圧片18、18の端面同士の間の隙間20、20(図7参照)の厚さを、前記両先端部を塑性変形させた状態で正の値とし(隙間20、20を残し)、これら両先端部の変形量を調整する事もできる。又、前記両押圧片18、18の内側面で前記小径部14の先端部の外周面と当接する部分の形状は、前述した図7〜8に示す様な断面が円弧状の凹部19、19に限らず、前記小径部14の先端部の外周面の径方向反対位置を、互いに近付く方向に押圧できれば、平面や断面形状がV字形の面等とする事もできる。更に、断面円弧状とする場合でも、前記小径部14の先端部外周面の曲率半径との大小関係は、何れでも良い。又、前記面取り部21の基端部(大径側端部)は、前記両押圧片18、18により、アウタシャフト12aとインナシャフト13aとを押圧する際に、これら両押圧片18、18の軸方向中間部(これら両押圧片18、18の厚さ範囲内)の径方向内方に位置させている。前記両先端部同士の係合部を塑性変形したならば、次いで、前記アウタシャフト12aと前記インナシャフト13aとを軸方向に相対変位させて、前記小径部14の先端部を前記大径部16aの基端部に、この大径部16aの先端部にこの小径部14の基端部を、それぞれ圧入嵌合させる。又、これら小径部14の中間部と大径部16aの中間部とは、互いに緩く嵌合させる。 In order to manufacture the shock absorbing steering shaft of this reference example configured as described above, first, as shown in FIG. 2, the tip of the large diameter portion 16 a is engaged with the tip of the small diameter portion 14. . And the outer peripheral surface of the front-end | tip part of this small diameter part 14 is pressed radially inward by the said both pressing pieces 18 and 18, and similarly to the case of FIGS. The distal end portion of the small-diameter portion 14 and the distal end portion of the large-diameter portion 16a are plastically deformed in the radial direction so that a cross-sectional shape related to a virtual plane orthogonal to the central axis of the steering shaft 3b is an ellipse. At this time, the pressing force for pressing both the pressing pieces 18, 18 may be adjusted. That is, the thicknesses of the gaps 20 and 20 (see FIG. 7 ) between the end surfaces of both the pressing pieces 18 and 18 are set to positive values in a state where both the tip portions are plastically deformed (the gaps 20 and 20 are set to be the same). The amount of deformation of both the tip portions can be adjusted. The shape of the portion of the inner surface of the pressing pieces 18, 18 that contacts the outer peripheral surface of the tip of the small-diameter portion 14 is a concave portion 19, 19 having a circular cross section as shown in FIGS. Not limited to this, as long as the radially opposite positions of the outer peripheral surface of the distal end portion of the small-diameter portion 14 can be pressed toward each other, the plane or the cross-sectional shape can be a V-shaped surface or the like. Furthermore, even when the cross-sectional arc shape is used, the magnitude relationship with the curvature radius of the outer peripheral surface of the tip end portion of the small diameter portion 14 may be any. The base end portion (large-diameter side end portion) of the chamfered portion 21 is formed by the pressing pieces 18 and 18 when the outer shaft 12a and the inner shaft 13a are pressed by the pressing pieces 18 and 18. It is located inward in the radial direction of the axially intermediate portion (within the thickness range of both the pressing pieces 18, 18). If the engaging portion between the two tip portions is plastically deformed, then the outer shaft 12a and the inner shaft 13a are relatively displaced in the axial direction, and the tip portion of the small diameter portion 14 is moved to the large diameter portion 16a. The base end portion of the small-diameter portion 14 is press-fitted into the base end portion of the large-diameter portion 16a. Further, the intermediate portion of the small diameter portion 14 and the intermediate portion of the large diameter portion 16a are loosely fitted to each other.

上述の様に構成する本参考例の衝撃吸収式ステアリングシャフト及びその製造方法によれば、前記ステアリングシャフト3bを製造する際に、前記インナシャフト13aの大径部16aの先端縁と前記アウタシャフト12aの小径部14の内周面との間にかじりが発生するのを防止し、前記ステアリングシャフト3bの製造コストの上昇を抑えつつ、優れた衝撃エネルギ吸収性能を発揮できる衝撃吸収式ステアリングシャフトを組み立てる事ができる。この理由は、前記大径部16aの先端部外周縁に断面形状が部分円弧状(R状)の面取り部21を設ける事で、この大径部16aの先端部のうち、先端縁部分の外径をこの大径部16aの先端縁に向かう程小さくしているからである。この様な構成を採用している為、前記ステアリングシャフト3bを製造する際に、前記アウタシャフト12aと前記インナシャフト13aとを互いに近づく方向に軸方向に相対変位させる際に、前記大径部16aの先端縁と前記小径部14の内周面とが強く擦れ合う事がない。即ち、この大径部16aの先端縁部分の外径が小さくなっている為、この大径部16aの先端部外周縁(尖鋭な端縁)と、前記小径部14の内周面とは当接しない。この大径部16aの先端縁部分のうち、この小径部14の内周面と当接する部分には、R状の面取り部21を設け、断面形状の曲率半径を大きくしているので、前記先端縁部分と前記小径部14の内周面との当接圧は低い。この為、前記両シャフト12a、13a同士を相対変位させる際に、前記大径部16aの先端縁部分と前記小径部14の内周面との間に作用する摩擦力を小さく抑える事ができて、この先端縁部分がこの内周面に食い込む事を防止でき、この内周面にかじりによる余肉部(むしれ)が発生するのを防止できる。 According to the shock absorbing steering shaft and the manufacturing method thereof of the present embodiment configured as described above, when manufacturing the steering shaft 3b, the leading edge of the large-diameter portion 16a of the inner shaft 13a and the outer shaft 12a Assembling an impact-absorbing steering shaft that prevents the occurrence of galling with the inner peripheral surface of the small-diameter portion 14 and suppresses an increase in the manufacturing cost of the steering shaft 3b and exhibits excellent impact energy absorption performance. I can do things. The reason for this is that by providing a chamfered portion 21 having a partial arc shape (R shape) in the outer peripheral edge of the distal end portion of the large-diameter portion 16a, out of the distal end edge portion of the distal end portion of the large-diameter portion 16a. This is because the diameter is made smaller toward the leading edge of the large diameter portion 16a. Since such a configuration is adopted, when the steering shaft 3b is manufactured, when the outer shaft 12a and the inner shaft 13a are relatively displaced in the axial direction in a direction approaching each other, the large-diameter portion 16a. The tip edge of the small diameter portion and the inner peripheral surface of the small diameter portion 14 do not rub against each other. That is, since the outer diameter of the tip edge portion of the large diameter portion 16a is small, the outer peripheral edge (sharp edge) of the large diameter portion 16a and the inner peripheral surface of the small diameter portion 14 are not matched. Do not touch. Of the leading edge portion of the large-diameter portion 16a, an R-shaped chamfered portion 21 is provided at a portion that contacts the inner peripheral surface of the small-diameter portion 14, and the curvature radius of the cross-sectional shape is increased. The contact pressure between the edge portion and the inner peripheral surface of the small diameter portion 14 is low. Therefore, when the shafts 12a and 13a are relatively displaced, the frictional force acting between the tip edge portion of the large-diameter portion 16a and the inner peripheral surface of the small-diameter portion 14 can be reduced. The leading edge portion can be prevented from biting into the inner peripheral surface, and the occurrence of a surplus portion due to galling on the inner peripheral surface can be prevented.

尚、前記面取り部21の基端部(大径側端部)は、前記両シャフト12a、13a同士を塑性変形する際に、前記両押圧片18、18の軸方向中間部の径方向内方に位置させている為、前記大径部16aの先端縁部分で外径が小さくなっている部分を径方向内方に押圧する力を適切に制御(中間寄り部分よりも大きくなる事を防止)できる。この結果、前記大径部16aの先端縁と小径部14の内周面との擦れ合い部でかじりが生じる事を、より安定して防止できる。   The base end portion (large-diameter side end portion) of the chamfered portion 21 is radially inward of the intermediate portion in the axial direction of the pressing pieces 18 and 18 when the shafts 12a and 13a are plastically deformed. Therefore, the force of pressing the portion whose outer diameter is small at the tip edge portion of the large diameter portion 16a inward in the radial direction is appropriately controlled (preventing becoming larger than the intermediate portion) it can. As a result, it is possible to more stably prevent galling at the rubbing portion between the tip edge of the large diameter portion 16a and the inner peripheral surface of the small diameter portion 14.

[実施の形態の1例
図3は、本発明の実施の形態の1例を示している。本例の場合には、インナシャフト13bの大径部16bの先端縁部分(図3の右側)に、この大径部16bの先端縁に向かう程この先端縁部分の外径が小さくなる様に、母線形状が直線状の(部分円すい面状の)テーパ面部23を設けている。このテーパ面部23のテーパ角θは、このテーパ面部23とアウタシャフト12aの小径部14(図1〜2、5〜8参照)の内周面との当接圧を小さくする為、60度以下とする事が望ましい。前記テーパ角θを60度よりも大きくすると、前記テーパ面部23の基端部と前記大径部16bの中間寄り部分との連続部の角度が小さく(150度未満に)なり、この連続部で、前記小径部14の内周面との当接圧が高くなる可能性がある。この結果、この連続部とこの小径部14の内周面との擦れ合い部でかじりが発生するのを防止できなくなる可能性がある。
[ Example of Embodiment]
FIG. 3 shows an example of an embodiment of the present invention . In the case of this example, the outer diameter of the leading edge portion becomes smaller toward the leading edge of the large diameter portion 16b toward the leading edge portion (right side in FIG. 3) of the large diameter portion 16b of the inner shaft 13b. A tapered surface portion 23 having a straight line shape (partial conical surface shape) is provided. The taper angle θ of the taper surface portion 23 is 60 degrees or less in order to reduce the contact pressure between the taper surface portion 23 and the inner peripheral surface of the small diameter portion 14 (see FIGS. 1-2 and 5-8 ) of the outer shaft 12a. It is desirable that When the taper angle θ is larger than 60 degrees, the angle of the continuous portion between the proximal end portion of the tapered surface portion 23 and the intermediate portion of the large diameter portion 16b becomes small (less than 150 degrees). The contact pressure with the inner peripheral surface of the small diameter portion 14 may increase. As a result, it may not be possible to prevent galling at the rubbing portion between the continuous portion and the inner peripheral surface of the small diameter portion 14.

更に、本例の場合には、前記テーパ面部23の基端部(大径側端部)である、前記連続部に、断面形状が部分円弧状(R状)である、面取り部21aを設けている。本例の場合には、この連続部の角度を大きく(150度以上に)した事と、この連続部に面取り部21aを設けた事とにより、この連続部と前記小径部14の内周面との当接部の面圧を、より低く抑え、この当接部でのかじりの発生を、より効果的に抑えられる様にしている。尚、前記面取り部21aの基端部(大径側端部)は、前記両シャフト12a、13b同士を塑性変形する際に、1対の押圧片18、18の軸方向中間部(これら両押圧片18、18の厚さ範囲内)の径方向内方に位置させる。
その他の部分の構成及び作用は、上述した参考例の第1例と同様であるから、同等部分には同一符号を付して、重複する説明は省略する。
Furthermore, in the case of this example, a chamfered portion 21 a having a partial arc shape (R shape) is provided in the continuous portion, which is a base end portion (large diameter side end portion) of the tapered surface portion 23. ing. In the case of this example, the angle of the continuous portion is increased (150 degrees or more) and the chamfered portion 21a is provided in the continuous portion, so that the continuous portion and the inner peripheral surface of the small diameter portion 14 are provided. The surface pressure of the abutting portion is suppressed to be lower, and the occurrence of galling at the abutting portion can be more effectively suppressed. The base end portion (large-diameter side end portion) of the chamfered portion 21a is an intermediate portion in the axial direction of the pair of pressing pieces 18, 18 when the shafts 12a, 13b are plastically deformed. It is positioned radially inwardly within the thickness range of the pieces 18, 18.
Since the configuration and operation of the other parts are the same as those in the first example of the reference example described above, the same parts are denoted by the same reference numerals, and redundant description is omitted.

1 車体
2 ステアリングコラム
3、3a〜3b ステアリングシャフト
4 ステアリングホイール
5a、5b 自在継手
6 中間シャフト
7 ステアリングギヤユニット
8 入力軸
9 タイロッド
10 電動モータ
11 アウタコラム
12、12a アウタシャフト
13、13a〜13b インナシャフト
14 小径部
15 雌セレーション
16、16a〜16b 大径部
17 雄セレーション
18 押圧片
19 凹部
20 隙間
21、21a 面取り部
22 凹孔
23 テーパ面部
DESCRIPTION OF SYMBOLS 1 Car body 2 Steering column 3, 3a-3b Steering shaft 4 Steering wheel 5a, 5b Universal joint 6 Intermediate shaft 7 Steering gear unit 8 Input shaft 9 Tie rod 10 Electric motor 11 Outer column 12, 12a Outer shaft 13, 13a-13b Inner shaft 14 Small diameter portion 15 Female serration 16, 16a to 16b Large diameter portion 17 Male serration
18 pressing pieces 19 recessed portions 20 clearances 21 and 21a chamfered portions 22 recessed holes 23 tapered surface portions

Claims (4)

少なくとも先端縁から中間部に掛けての部分の内周面に雌セレーションを形成した管状のアウタシャフトと、少なくとも先端縁から中間部に掛けての部分の外周面にこの雌セレーションと係合する雄セレーションを形成したインナシャフトとを、中心軸に直交する仮想平面に関する断面形状が楕円形である前記アウタシャフトの先端部に前記インナシャフトの中間部を、同じく断面形状が楕円形であるこのインナシャフトの先端部を前記アウタシャフトの中間部に、それぞれ、二次衝突時に加わる衝撃に伴い、前記両シャフト同士が軸方向に相対変位可能な嵌合強度で内嵌固定する事により、前記アウタシャフトと前記インナシャフトとを結合して成る衝撃吸収式ステアリングシャフトに於いて、前記インナシャフトの先端部のうち、先端縁寄り部分の外径が先端縁に向かう程小さくなっている事を特徴とする衝撃吸収式ステアリングシャフト。   A tubular outer shaft in which female serrations are formed on the inner peripheral surface of at least a portion extending from the leading edge to the intermediate portion, and a male that engages with the female serrations on the outer peripheral surface of at least the portion extending from the leading edge to the intermediate portion. The inner shaft formed with serrations, the inner shaft at the tip of the outer shaft whose elliptical cross-sectional shape perpendicular to the central axis is elliptical, and the inner shaft whose cross-sectional shape is also elliptical The inner shaft of the outer shaft is fitted and fixed to the intermediate portion of the outer shaft with a fitting strength that allows the shafts to be displaced relative to each other in the axial direction in response to an impact applied during a secondary collision. An impact absorbing type steering shaft formed by coupling the inner shaft to a tip edge of a tip portion of the inner shaft. Ri moiety impact absorbing type steering shaft outside diameter characterized in that is smaller as toward the leading edge of. 前記アウタシャフトの一端部に少なくとも内径が小さい小径部を設け、この小径部の内周面に雌セレーションを形成しており、前記インナシャフトの一端部に少なくとも外径が大きい大径部を設け、この大径部の外周面に前記雌セレーションと係合する雄セレーションを形成し、この大径部の先端部のうち、先端縁寄り部分の外径を先端縁に向かう程小さくしており、中心軸に直交する仮想平面に関する断面形状が楕円形である前記小径部の先端部にこの大径部の基端部を、同じく断面形状が楕円形であるこの大径部の先端部を前記小径部の基端部に、それぞれ、二次衝突時に加わる衝撃に伴い、前記両シャフト同士が軸方向に相対変位可能な嵌合強度で内嵌固定する事により、前記アウタシャフトと前記インナシャフトとを結合している、請求項1に記載の衝撃吸収式ステアリングシャフト。   A small diameter portion having at least a small inner diameter is provided at one end portion of the outer shaft, a female serration is formed on an inner peripheral surface of the small diameter portion, and a large diameter portion having at least a large outer diameter is provided at one end portion of the inner shaft, A male serration that engages with the female serration is formed on the outer peripheral surface of the large-diameter portion, and the outer diameter of the portion near the tip edge of the tip portion of the large-diameter portion is reduced toward the tip edge, The proximal end portion of the large diameter portion is disposed at the distal end portion of the small diameter portion having an elliptical cross-sectional shape perpendicular to the axis, and the small diameter portion is disposed at the distal end portion of the large diameter portion having an elliptical sectional shape. The outer shaft and the inner shaft are coupled to each other by fixing the inner shaft with a fitting strength at which the shafts can be displaced relative to each other in the axial direction in response to an impact applied at the time of a secondary collision. doing, Shock absorbing steering shaft according to Motomeko 1. 少なくとも先端縁から中間部に掛けての部分の内周面に雌セレーションを形成した管状のアウタシャフトと、少なくとも先端縁から中間部に掛けての部分の外周面にこの雌セレーションと係合する雄セレーションを形成したインナシャフトとを、前記アウタシャフトの先端部とこのインナシャフトの先端部とを係合させた状態で、このアウタシャフトの外周面を径方向内方に押圧する事により、このアウタシャフトの先端部及び前記インナシャフトの先端部を径方向に塑性変形させた後、このアウタシャフトとこのインナシャフトとを互いに近づく方向に軸方向に相対変位させて、このアウタシャフトの先端部をこのインナシャフトの中間部に圧入嵌合すると共に、このインナシャフトの先端部を前記アウタシャフトの中間部に圧入嵌合させ、このアウタシャフトの先端部と中間部との間部分と、前記インナシャフトの先端部と中間部との間部分とを互いに緩く係合させる衝撃吸収式ステアリングシャフトの製造方法に於いて、前記インナシャフトとして、このインナシャフトの先端部のうち、先端寄り部分の外径が先端縁に向かう程小さくなっているものを使用する事を特徴とする衝撃吸収式ステアリングシャフトの製造方法。   A tubular outer shaft in which female serrations are formed on the inner peripheral surface of at least a portion extending from the leading edge to the intermediate portion, and a male that engages with the female serrations on the outer peripheral surface of at least the portion extending from the leading edge to the intermediate portion. By pressing the outer peripheral surface of the outer shaft radially inward in a state where the tip of the outer shaft and the tip of the inner shaft are engaged with the inner shaft on which the serration is formed, After plastically deforming the distal end of the shaft and the distal end of the inner shaft in the radial direction, the outer shaft and the inner shaft are relatively displaced in the axial direction so as to approach each other, and the distal end of the outer shaft is The inner shaft is press-fitted to the middle part, and the inner shaft tip is press-fitted to the outer shaft middle part. In the method of manufacturing the shock absorbing steering shaft, the portion between the tip portion and the middle portion of the outer shaft and the portion between the tip portion and the middle portion of the inner shaft are loosely engaged with each other. A method for manufacturing an impact-absorbing steering shaft, wherein the inner shaft has a distal end portion whose outer diameter decreases toward the leading edge. 前記アウタシャフトは、一端部に少なくとも内径を小さくした小径部を設け、この小径部の内周面に雌セレーションを形成しているものであり、前記インナシャフトは、一端部に少なくとも外径を大きくした大径部を設け、この大径部の外周面に前記雌セレーションと係合する雄セレーションを形成しており、この大径部の先端部のうち、先端縁寄り部分の外径が先端縁に向かう程小さくなっているものであり、前記小径部の先端部と前記大径部の先端部とを係合させた状態で、この小径部の外周面を径方向内方に押圧する事により、この小径部の先端部及び前記大径部の先端部を径方向に塑性変形させた後、前記アウタシャフトと前記インナシャフトとを互いに近づく方向に軸方向に相対変位させて、前記小径部の先端部を前記大径部の基端部に圧入嵌合すると共に、この大径部の先端部をこの小径部の基端部に圧入嵌合させ、これら小径部の中間部と大径部の中間部とを互いに緩く係合させる、請求項3に記載の衝撃吸収式ステアリングシャフトの製造方法。   The outer shaft is provided with a small-diameter portion having at least a small inner diameter at one end portion, and a female serration is formed on the inner peripheral surface of the small-diameter portion. The inner shaft has at least a large outer diameter at one end portion. And a male serration that engages with the female serration is formed on the outer peripheral surface of the large diameter portion, and the outer diameter of the distal end portion of the large diameter portion is the tip edge. By pressing the outer peripheral surface of the small diameter portion inward in the radial direction in a state where the tip portion of the small diameter portion and the tip portion of the large diameter portion are engaged. Then, after plastically deforming the distal end portion of the small diameter portion and the distal end portion of the large diameter portion in the radial direction, the outer shaft and the inner shaft are relatively displaced in the axial direction so as to approach each other, and the small diameter portion The tip part is the base of the large diameter part. And press-fitting and fitting the distal end portion of the large-diameter portion to the proximal end portion of the small-diameter portion, and loosely engaging the intermediate portion of the small-diameter portion and the intermediate portion of the large-diameter portion with each other, A method for manufacturing the shock absorbing steering shaft according to claim 3.
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11327382B2 (en) 2014-11-26 2022-05-10 View, Inc. Counter electrode for electrochromic devices
WO2022181701A1 (en) * 2021-02-26 2022-09-01 ミネベアミツミ株式会社 Shaft support structure, magnetic detection device, and absolute encoder

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JP3168841B2 (en) * 1994-09-22 2001-05-21 日本精工株式会社 Manufacturing method of shock absorbing steering shaft
JP2005297723A (en) * 2004-04-09 2005-10-27 Nsk Ltd Vehicular steering telescopic shaft
JP3716590B2 (en) * 1997-12-03 2005-11-16 日本精工株式会社 Method for manufacturing shock absorbing steering shaft
JP2008087531A (en) * 2006-09-29 2008-04-17 Nsk Ltd Electrically-driven telescopic adjustment type steering device

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JP3716590B2 (en) * 1997-12-03 2005-11-16 日本精工株式会社 Method for manufacturing shock absorbing steering shaft
JP2001030920A (en) * 1999-03-04 2001-02-06 Nsk Ltd Shock absorbing steering shaft and manufacture thereof
JP2005297723A (en) * 2004-04-09 2005-10-27 Nsk Ltd Vehicular steering telescopic shaft
JP2008087531A (en) * 2006-09-29 2008-04-17 Nsk Ltd Electrically-driven telescopic adjustment type steering device

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11327382B2 (en) 2014-11-26 2022-05-10 View, Inc. Counter electrode for electrochromic devices
WO2022181701A1 (en) * 2021-02-26 2022-09-01 ミネベアミツミ株式会社 Shaft support structure, magnetic detection device, and absolute encoder

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