JP6660149B2 - Differential device - Google Patents

Description

本発明は、差動装置、特にデフケースと、デフケースに収納されて該デフケースの回転力を互いに独立した一対の出力軸に分配して伝達する差動機構とを備える差動装置の改良に関する。   The present invention relates to a differential device, and more particularly to an improvement of a differential device including a differential case and a differential mechanism housed in the differential case and distributing and transmitting the rotational force of the differential case to a pair of output shafts independent of each other.

上記差動装置として、例えばデフケースが、回転力を受ける入力部を有すると共に少なくとも軸方向の一方側の端部が開放された円筒状の入力部材と、入力部材の開放端部を塞ぐ少なくとも１個のカバー部とを備えた差動装置が、例えば特許文献１にも記載されているように公知であり、この従来装置では、入力部としてのドリブンギヤの内周部と、デフケースの外周部とを接合一体化するに当たり、圧入手段と溶接手段とを併用している。   As the differential device, for example, a differential case has a cylindrical input member having an input portion for receiving a rotational force and having at least one axial end opened, and at least one closing an open end of the input member. Is known as described in, for example, Patent Document 1. In this conventional device, an inner peripheral portion of a driven gear as an input portion and an outer peripheral portion of a differential case are provided. In joining and integrating, the press-fitting means and the welding means are used together.

特許第５５０９９１０号公報Patent No. 5509910 特許第４８０３８７１号公報Japanese Patent No. 4803871 特開２００２−３６４７２８号公報JP-A-2002-364728

ところで上記従来装置のように入力部とデフケースとの間を、圧入手段と溶接手段とを併用して接合すると、溶接の際に溶接部周辺に生じる熱歪の影響に加えて、圧入の際に圧入部周辺に生じる機械的な歪の影響も加わることで、入力部及びデフケース、延いては差動装置全体の組立精度が低下する虞れがある。   By the way, when the input portion and the differential case are joined together by using the press-fitting means and the welding means as in the above-described conventional device, in addition to the effect of thermal strain generated around the welded portion at the time of welding, at the time of press-fitting, Due to the influence of mechanical distortion generated around the press-fitting portion, the assembling accuracy of the input portion, the differential case, and further, the entire differential device may be reduced.

尚、上記従来装置では、差動装置における入力部の配置形態、例えばヘリカルギヤとすることに関係して、デフケースに対して入力部側からスラスト荷重が少なからず作用する場合があり、その場合には入力部とデフケースとの境界部である溶接部に応力集中が生じ易くなって、溶接部の耐久性を低下させる等の虞れもある。   In the above conventional device, there is a case where a thrust load acts on the differential case from the input portion side not a little, in relation to the arrangement form of the input portion in the differential device, for example, a helical gear. Stress concentration is likely to occur in a welded portion, which is a boundary portion between the input portion and the differential case, and there is a possibility that the durability of the welded portion is reduced.

そして、以上のような課題は、デフケースを構成する円筒状の入力部材とそれの開放端部を塞ぐカバー部との間の結合に、圧入手段と溶接手段とを併用した場合にも、同様に発生する。   The above-described problem is also caused when the press-fitting means and the welding means are used in combination for the connection between the cylindrical input member constituting the differential case and the cover portion closing the open end thereof. appear.

本発明は、斯かる事情に鑑みてなされたもので、上記問題を解決し得る前記差動装置を提供することを目的とする。   The present invention has been made in view of the above circumstances, and has as its object to provide the above-described differential device that can solve the above-described problem.

上記目的を達成するために、本発明に係る差動装置は、デフケースと、前記デフケースに収納されて該デフケースの回転力を互いに独立した一対の出力軸に分配して伝達する差動機構とを備えた差動装置であって、前記デフケースが、回転力を受ける入力部を有すると共に少なくとも軸方向の一方側の端部が開放された円筒状の入力部材と、前記入力部材の前記軸方向の一方側の端部の開放部分を塞ぐ少なくとも１個のカバー部とを備え、前記入力部材は、前記カバー部を前記入力部材の軸方向に嵌合して溶接させる被溶接部と、前記被溶接部よりも前記入力部材の半径方向内方側且つ軸方向内方側に在って前記カバー部を圧入させる被圧入部と、前記被溶接部及び前記被圧入部間を接続して前記カバー部との間に圧入の際の前記被圧入部の変形を許容する空間を形成する接続面とを有し、前記接続面の、前記被溶接部に連なる一端部は、該被溶接部から前記半径方向外方側に延出し、前記被圧入部の一部と前記空間とは、前記入力部材の回転中心から放射方向に見て互いにオーバラップするように配置される（これを第１の特徴とする）。
In order to achieve the above object, a differential device according to the present invention includes a differential case, and a differential mechanism that is housed in the differential case and distributes and transmits the rotational force of the differential case to a pair of output shafts independent of each other. A differential device, wherein the differential case has a cylindrical input member having an input portion for receiving a rotational force and having at least one end in an axial direction opened, and the axial direction of the input member in the axial direction. At least one cover portion for closing an open portion at one end, wherein the input member is configured to weld the cover portion by fitting the cover portion in an axial direction of the input member, and the welded portion; A press-fitted portion which is located radially inward and axially inward of the input member relative to the input portion and press-fits the cover portion, and the cover portion which connects between the welded portion and the press-fitted portion. Between the press-fitted part at the time of press-fitting And a connecting surface to form a space that allows the shape of the connecting surface, the one end portion continuous to the weld, extending the radially outer side from該被weld of the press-fitted portion The part and the space are arranged so as to overlap each other when viewed in the radial direction from the rotation center of the input member (this is a first feature).

好適には、前記カバー部が、前記出力軸を同心状に囲繞するボス部と、前記ボス部から前記半径方向外方側に張出すように連設される側壁部とを有し、前記側壁部の外周部には、前記被溶接部に嵌合して溶接される大径部と、前記大径部の軸方向内端に段差面を介して連なり且つ前記被圧入部に圧入される小径部とが形成され、前記被圧入部の軸方向外端が前記段差面に当接又は近接していると共に、前記接続面が、前記軸方向外端又はその近傍部から前記半径方向外方に向かうにつれて前記段差面から徐々に離間する傾斜部を有している（これを第２の特徴とする）。
Preferably, the cover portion has a boss portion concentrically surrounding the output shaft, and a side wall portion continuously provided so as to project radially outward from the boss portion, The outer peripheral portion of the portion has a large-diameter portion fitted and welded to the welded portion, and a small-diameter portion connected to the axially inner end of the large-diameter portion via a stepped surface and pressed into the press-fitted portion. Part is formed, and the axially outer end of the press-fitted portion is in contact with or in proximity to the step surface, and the connection surface is radially outward from the axially outer end or the vicinity thereof. It has an inclined portion that gradually separates from the step surface as it goes (this is a second feature) .

第１の特徴によれば、デフケースの入力部材が、カバー部を入力部材の軸方向に嵌合して溶接させる被溶接部と、被溶接部よりも入力部材の半径方向内方側且つ軸方向内方側に在ってカバー部を圧入させる被圧入部と、被溶接部及び被圧入部間を接続してカバー部との間に圧入の際の被圧入部の変形を許容する空間を形成する接続面とを有しているので、圧入の際に入力部材の被圧入部周辺の撓み変形が許容されて、被圧入部周辺に生じる機械的な歪を緩和することができ、歪の影響で入力部材及びカバー部、延いては差動装置全体の組立精度が低下するのを効果的に防止できる。また、差動装置における入力部材の配置形態等により回転中の入力部材に対して駆動源側からスラスト荷重が少なからず作用する場合があっても、接続面の、被溶接部に連なる一端部は、被溶接部から半径方向外方側に延出しているので、その延出部側にスラスト荷重に因る応力を分散させることができ、これにより、入力部材とカバー部との溶接部に応力集中が生じるのを効果的に防止できて、応力集中による溶接部の耐久性低下を回避可能となる。また、被圧入部の一部と前記空間とは、入力部材の回転中心から放射方向に見て互いにオーバラップするように配置されるので、圧入の際に入力部材の被圧入部周辺が半径方向外方に撓み変形し易くなり、圧入による歪を効果的に緩和でき、歪の影響で入力部材及びカバー部の組立精度が低下するのを一層効果的に防止できる。
According to a first aspect, the input member of the differential case, and welded portion which is welded by fitting the cover portion in the axial direction of the input member, the radially inner side and the axial direction of the input member than the welded portion A space that allows deformation of the press-fitted part at the time of press-fitting is formed between the press-fitted part on the inner side where the cover part is press-fitted and the welded part and the press-fitted part are connected and the cover part is formed. The press-fitting allows the input member to be deformed around the press-fitted portion at the time of press-fitting, so that the mechanical strain generated around the press-fitted portion can be reduced, and the influence of the strain can be reduced. Thus, it is possible to effectively prevent the assembling accuracy of the input member and the cover portion, and hence the differential device as a whole, from being lowered. Further, even if a thrust load may be applied to the rotating input member from the drive source side due to the arrangement of the input member in the differential device or the like, one end of the connection surface, which is continuous with the welded portion, may be provided. , Since it extends radially outward from the welded portion, it is possible to disperse the stress due to the thrust load on the extended portion side, and thereby the stress is applied to the welded portion between the input member and the cover portion. Concentration can be effectively prevented, and a reduction in the durability of the weld due to stress concentration can be avoided. In addition, since the part of the press-fitted portion and the space overlap each other when viewed radially from the rotation center of the input member, the periphery of the press-fitted portion of the input member at the time of press-fit is radially It becomes easy to flex and deform outward, so that distortion due to press-fitting can be effectively alleviated, and a decrease in assembly accuracy of the input member and the cover due to the distortion can be more effectively prevented.

また特に第２の特徴によれば、カバー部は、出力軸を同心状に囲繞するボス部と、ボス部から半径方向外方側に張出すように連設される側壁部とを有し、側壁部の外周部には、被溶接部に嵌合して溶接される大径部と、大径部の軸方向内端に段差面を介して連なり且つ被圧入部に圧入される小径部とが形成され、段差面に被圧入部の軸方向外端が当接又は近接していると共に、接続面が被圧入部の軸方向外端又はその近傍部から半径方向外方に向かうにつれて段差面から徐々に離間する傾斜部を有しているので、被圧入部と小径部との圧入接触面積を十分確保しながら、入力部材の被圧入部周辺の半径方向外方への撓み変形を容易化することができる。
According to the second feature, in particular, the cover portion includes a boss portion that concentrically surrounds the output shaft, and a side wall portion that is continuously provided so as to project radially outward from the boss portion, On the outer peripheral portion of the side wall portion, a large-diameter portion fitted and welded to the welded portion, and a small-diameter portion connected to the axially inner end of the large-diameter portion via a stepped surface and pressed into the press-fitted portion. Is formed, and the axially outer end of the press-fitted portion is in contact with or close to the stepped surface, and the stepped surface is radially outward from the axially outer end of the press-fitted portion or a portion in the vicinity thereof. Has an inclined portion that gradually separates from the press-fitted part, while ensuring a sufficient press-fit contact area between the press-fitted part and the small-diameter part, facilitating radially outward deformation of the input member around the press-fitted part. can do.

本発明の第１実施形態に係る差動装置及びその周辺の縦断面図（図２の１−１線断面図）FIG. 2 is a longitudinal sectional view of the differential device according to the first embodiment of the present invention and its periphery (a sectional view taken along line 1-1 in FIG. 2). 本発明の第１実施形態に係る差動装置の一部を破断した軸方向一方側の側面図（図１の２−２線断面図）1 is a side view of one side in the axial direction with a part of the differential device according to the first embodiment of the present invention broken away (a cross-sectional view taken along line 2-2 in FIG. 1). 本発明の第１実施形態に係る差動装置の軸方向他方側の要部側面図（図１の３−３線断面図）Side view of main part of the other side in the axial direction of the differential device according to the first embodiment of the present invention (sectional view taken along line 3-3 in FIG. 1). 図１の４矢視部の拡大図FIG. 図４の５−５線断面図FIG. 本発明の第２実施形態に係る差動装置のピニオン支持部を示す、図４対応の部分断面図FIG. 4 is a partial cross-sectional view corresponding to FIG. 4, showing a pinion support of a differential gear according to a second embodiment of the present invention. 本発明の第３実施形態に係る差動装置及びその周辺の縦断面図（図１対応図）Longitudinal sectional view of a differential device according to a third embodiment of the present invention and its periphery (corresponding to FIG. 1). 本発明の第３実施形態に係る差動装置の分解斜視図Exploded perspective view of a differential gear according to a third embodiment of the present invention. 従来の差動装置の一例を示す縦断面図Longitudinal sectional view showing an example of a conventional differential device ピニオンの歯数を１０とした時の歯数比率に対するギヤ強度変化率の関係を示すグラフGraph showing the relationship between the gear ratio and the gear ratio when the number of teeth of the pinion is set to 10. ピッチ円錐距離の変化率に対するギヤ強度変化率の関係を示すグラフGraph showing the relationship between the rate of change in pitch cone distance and the rate of change in gear strength ピニオンの歯数を１０とした時のギヤ強度を１００％維持する場合における歯数比率に対するピッチ円錐距離の変化率の関係を示すグラフA graph showing the relationship between the ratio of the number of teeth and the rate of change of the pitch cone distance when the gear strength is maintained at 100% when the number of teeth of the pinion is set to 10. ピニオンの歯数を１０とした時の歯数比率と、シャフト径／ピッチ円錐距離の比率との関係を示すグラフGraph showing the relationship between the ratio of the number of teeth when the number of teeth of the pinion is set to 10, and the ratio of the shaft diameter / pitch cone distance. ピニオンの歯数を６とした時の歯数比率と、シャフト径／ピッチ円錐距離の比率との関係を示すグラフGraph showing the relationship between the ratio of the number of teeth when the number of teeth of the pinion is 6, and the ratio of the shaft diameter / pitch cone distance. ピニオンの歯数を１２とした時の歯数比率と、シャフト径／ピッチ円錐距離の比率との関係を示すグラフGraph showing the relationship between the ratio of the number of teeth when the number of teeth of the pinion is 12 and the ratio of the shaft diameter / pitch cone distance. ピニオンの歯数を２０とした時の歯数比率と、シャフト径／ピッチ円錐距離の比率との関係を示すグラフGraph showing the relationship between the ratio of the number of teeth when the number of teeth of the pinion is set to 20, and the ratio of the shaft diameter / pitch cone distance.

本発明の実施の形態を、添付図面に示す本発明の好適な実施例に基づいて以下に説明する。   Embodiments of the present invention will be described below based on preferred embodiments of the present invention shown in the accompanying drawings.

先ず、図１〜図５を参照して、本発明の第１実施形態について説明する。差動装置Ｄは、自動車に搭載されるエンジン（図示せず）から伝達された回転駆動力を、左右一対の車軸に連なる左右一対の出力軸Ａ，Ａ′に分配して伝達することにより、左右車軸を、差動回転を許容しつつ駆動するためのものであって、例えば車体前部のエンジンの横に配置されたミッションケース１内に収容、支持されている。   First, a first embodiment of the present invention will be described with reference to FIGS. The differential device D distributes and transmits the rotational driving force transmitted from an engine (not shown) mounted on an automobile to a pair of left and right output shafts A and A ′ connected to a pair of left and right axles, The left and right axles are driven while allowing differential rotation, and are accommodated and supported, for example, in a transmission case 1 arranged beside the engine at the front of the vehicle body.

差動装置Ｄは、エンジンから回転力を受けるファイナルドリブンギヤとしての入力歯部Ｉｇと、入力歯部Ｉｇと一体に回転するデフケースＤＣと、デフケースＤＣに収納されていて、入力歯部ＩｇからデフケースＤＣに伝達された回転力を左右一対の出力軸Ａ，Ａ′に分配して伝達する差動機構ＤＭとを備える。   The differential device D includes an input tooth portion Ig as a final driven gear that receives a rotational force from the engine, a differential case DC that rotates integrally with the input tooth portion Ig, and a differential case DC that is housed in the differential case DC. And a differential mechanism DM for distributing and transmitting the rotational force transmitted to the pair of left and right output shafts A and A ′.

差動機構ＤＭは、複数のピニオン（差動ギヤ）Ｐと、それらピニオンＰを回転自在に支持するピニオン支持部（差動ギヤ支持部）としてのピニオンシャフトＰＳと、ピニオンシャフトＰＳと共に回転し得るようピニオンシャフトＰＳを支持する短円筒状の入力部材Ｉと、ピニオンＰに対し左右両側より噛合し且つ左右一対の出力軸Ａ，Ａ′にそれぞれ接続される左右一対のサイドギヤ（出力ギヤ）Ｓとを備える。そして、入力部材Ｉの、軸方向少なくとも一方の端部（図示例では両端部）は開放されており、その開放部分を塞いで両サイドギヤＳの外側をそれぞれ覆う左右一対のカバー部Ｃ，Ｃ′が、入力部材Ｉにこれと一体に回転できるよう結合される。而して、入力部材Ｉ及びカバー部Ｃ，Ｃ′によりデフケースＤＣが構成される。   The differential mechanism DM can be rotated together with a plurality of pinions (differential gears) P, a pinion shaft PS as a pinion support portion (differential gear support portion) that rotatably supports the pinions P, and a pinion shaft PS. A pair of left and right side gears (output gears) S which mesh with the pinion P from both left and right sides and are connected to a pair of left and right output shafts A and A ', respectively. Is provided. At least one end (both ends in the illustrated example) of the input member I in the axial direction is open, and a pair of left and right cover portions C and C ′ covering the outside of both side gears S by closing the open portion. Is coupled to the input member I so as to be able to rotate integrally therewith. Thus, the differential case DC is constituted by the input member I and the cover portions C and C '.

尚、本実施形態ではピニオンＰを２個とし、ピニオン支持部としてのピニオンシャフトＰＳを入力部材Ｉの一直径線に沿って延びる直線棒状に形成して、それの両端部に２個のピニオンＰをそれぞれ支持させるようにしたものを示したが、ピニオンＰを３個以上設けてもよい。その場合には、ピニオンシャフトＰＳを、３個以上のピニオンＰに対応して入力部材Ｉの回転軸線Ｌから三方向以上に枝分かれして放射状に延びる交差棒状（例えばピニオンＰが４個の場合には十字状）に形成して、ピニオンシャフトＰＳの各先端部にピニオンＰを各々支持させるようにする。   In this embodiment, the number of the pinions P is two, and the pinion shaft PS as the pinion support is formed in a linear rod shape extending along one diameter line of the input member I, and two pinions P are provided at both ends thereof. Are shown, but three or more pinions P may be provided. In this case, the pinion shaft PS is formed in a cross bar shape that is radially branched from the rotation axis L of the input member I in three or more directions corresponding to three or more pinions P (for example, when there are four pinions P). Are formed in the shape of a cross, and the pinion P is supported at each end of the pinion shaft PS.

また、ピニオンシャフトＰＳにピニオンＰを図示例のように直接嵌合させてもよいし、或いは軸受ブッシュ等の軸受手段（図示せず）を介挿させてもよい。またピニオンシャフトＰＳは、全長に亘り略一様等径の軸状としてもよいし、或いは段付き軸状としてもよい。またピニオンシャフトＰＳの、ピニオンＰと嵌合する外周面に凹部を設けて、そこを油通路としてもよい。   Further, the pinion P may be directly fitted to the pinion shaft PS as in the illustrated example, or may be inserted through a bearing means (not shown) such as a bearing bush. Further, the pinion shaft PS may have a shaft shape having a substantially uniform diameter over the entire length, or may have a stepped shaft shape. Further, a concave portion may be provided on the outer peripheral surface of the pinion shaft PS to be fitted with the pinion P, and the concave portion may be used as an oil passage.

デフケースＤＣは、左右の軸受２を介してミッションケース１に回転自在に支持される。またミッションケース１に形成されて各出力軸Ａ，Ａ′が嵌挿される貫通孔１ａの内周と、各出力軸Ａ，Ａ′の外周との間には、その間をシールする環状シール部材３が介装される。またミッションケース１の底部には、ミッションケース１の内部空間に臨んで所定量の潤滑油を貯溜するオイルパン（図示せず）が設けられており、潤滑油がミッションケース１内においてデフケースＤＣその他の回転部材の回転により差動装置Ｄの周辺に飛散することで、デフケースＤＣの内外に存する機械連動部分を潤滑できるようになっている。   The differential case DC is rotatably supported by the transmission case 1 via left and right bearings 2. An annular seal member 3 is provided between the inner periphery of the through hole 1a formed in the transmission case 1 and into which each output shaft A, A 'is inserted and the outer periphery of each output shaft A, A'. Is interposed. An oil pan (not shown) for storing a predetermined amount of lubricating oil facing the internal space of the transmission case 1 is provided at the bottom of the transmission case 1. By rotating around the differential member D by the rotation of the rotating member, the mechanical interlocking portion existing inside and outside the differential case DC can be lubricated.

入力部材Ｉの外周部には、ファイナルドリブンギヤとしての入力歯部Ｉｇが設けられ、入力歯部Ｉｇは、エンジンの動力で回転駆動されるドライブギヤ（図示せず）と噛合する。また、入力歯部Ｉｇは、本実施形態ではヘリカルギヤとして形成されるが、本発明では、必ずしもヘリカルギヤとする必要はなく、通常のスパーギヤでもよい。なお、入力歯部Ｉｇは、本実施形態では入力部材Ｉの外周面にその横幅一杯（即ち軸方向全幅）に亘り形成されているが、入力歯部Ｉｇを入力部材Ｉよりも小幅に形成してもよい。   An input tooth portion Ig as a final driven gear is provided on an outer peripheral portion of the input member I, and the input tooth portion Ig meshes with a drive gear (not shown) that is rotated and driven by the power of the engine. Further, the input tooth portion Ig is formed as a helical gear in the present embodiment. However, in the present invention, the input tooth portion Ig does not necessarily need to be a helical gear, and may be a normal spur gear. In this embodiment, the input tooth portion Ig is formed on the outer peripheral surface of the input member I over the entire width thereof (that is, the entire width in the axial direction), but the input tooth portion Ig is formed to be smaller than the input member I. You may.

またピニオンＰ及びサイドギヤＳは、本実施形態ではベベルギヤに形成されており、しかもそれらの歯部を含む全体が各々鍛造等の塑性加工で形成されている。そのため、ピニオンＰ及びサイドギヤＳの歯部を切削加工する場合のような機械加工上の制約を受けることなく歯部を任意の歯数比を以て高精度に形成可能である。尚、ベベルギヤに代えて他のギヤを採用してもよく、例えばサイドギヤＳをフェースギヤとし且つピニオンＰをスパーギヤ又はヘリカルギヤとしてもよい。   In the present embodiment, the pinion P and the side gear S are formed as bevel gears, and the entirety including their teeth is formed by plastic working such as forging. For this reason, the teeth can be formed with an arbitrary ratio of the number of teeth with high precision without being restricted by machining such as when cutting the teeth of the pinion P and the side gear S. Note that another gear may be used instead of the bevel gear. For example, the side gear S may be a face gear and the pinion P may be a spur gear or a helical gear.

また一対のサイドギヤＳは、一対の出力軸Ａ，Ａ′の内端部がそれぞれスプライン嵌合４されて接続される円筒状の軸部Ｓｊと、軸部Ｓｊから入力部材Ｉの半径方向外方に離れた位置に在ってピニオンＰに噛合する円環状の歯部Ｓｇと、出力軸Ａ，Ａ′の軸線Ｌと直交する扁平なリング板状に形成されて軸部Ｓｊ及び歯部Ｓｇ間を一体に接続する中間壁部Ｓｗとを備える。   The pair of side gears S includes a cylindrical shaft portion Sj to which the inner ends of the pair of output shafts A and A 'are spline-fitted 4 and connected, and a radially outward portion of the input member I from the shaft portion Sj. A ring-shaped tooth portion Sg which is located at a distance from the shaft portion and meshes with the pinion P, and a flat ring-shaped plate orthogonal to the axis L of the output shafts A and A ', and is formed between the shaft portion Sj and the tooth portion Sg. And an intermediate wall portion Sw that integrally connects the two.

また、サイドギヤＳの中間壁部Ｓｗは、これの半径方向の幅ｔ１がピニオンＰの最大直径ｄ１よりも大きくなり、且つ中間壁部Ｓｗの、出力軸Ａ，Ａ′軸方向での最大肉厚ｔ２がピニオンシャフトＰＳの有効直径ｄ２よりも小さくなるように形成（図１参照）される。これにより、後述するように、サイドギヤＳの歯数Ｚ１をピニオンＰの歯数Ｚ２よりも十分大きく設定し得るようサイドギヤＳを十分に大径化することができ、且つ出力軸Ａ，Ａ′の軸方向でサイドギヤＳが十分に薄肉化できる。尚、本明細書において、「有効直径ｄ２」とは、ピニオンＰと別体又は一体に形成されてピニオンＰを支持し且つ入力部材Ｉに取付けられる、ピニオン支持部としての軸（即ち、ピニオンシャフトＰＳ或いは後述する支持軸部ＰＳ′）の外径ｄ２をいう。   The intermediate wall portion Sw of the side gear S has a radial width t1 larger than the maximum diameter d1 of the pinion P, and the maximum thickness of the intermediate wall portion Sw in the output shaft A, A 'axis direction. It is formed so that t2 is smaller than the effective diameter d2 of the pinion shaft PS (see FIG. 1). Thereby, as will be described later, the diameter of the side gear S can be made sufficiently large so that the number of teeth Z1 of the side gear S can be set to be sufficiently larger than the number of teeth Z2 of the pinion P, and the output shafts A and A ' The side gear S can be made sufficiently thin in the axial direction. In this specification, the “effective diameter d2” refers to a shaft (that is, a pinion shaft) that is formed separately from or integrally with the pinion P, supports the pinion P, and is attached to the input member I. PS or an outer diameter d2 of a support shaft portion PS ′) described later.

また一対のカバー部Ｃ，Ｃ′は、入力部材Ｉとは別体に各々形成されていて、後述するように入力部材Ｉに溶接される。各々のカバー部Ｃ，Ｃ′は、サイドギヤＳの軸部Ｓｊを同心状に囲繞して回転自在に嵌合支持する円筒状のボス部Ｃｂと、外側面を入力部材Ｉの回転軸線Ｌと直交する平坦面としてボス部Ｃｂの軸方向内端に一体に連設される板状の側壁部Ｃｓとを備えている。   Further, the pair of cover portions C and C 'are formed separately from the input member I, and are welded to the input member I as described later. Each of the cover portions C and C ′ has a cylindrical boss portion Cb that surrounds the shaft portion Sj of the side gear S concentrically and rotatably fits and supports the shaft portion Sj, and an outer surface thereof is orthogonal to the rotation axis L of the input member I. And a plate-shaped side wall Cs integrally provided at the inner end of the boss Cb in the axial direction as a flat surface.

次にピニオンシャフトＰＳの入力部材Ｉへの取付構造について、図４及び図５を併せて参照して説明する。入力部材Ｉは、ピニオン支持部としてのピニオンシャフトＰＳを支持するための環状の支持壁部Ｉｓを内周部に全周に亘り一体に突設しており、支持壁部Ｉｓは、出力軸Ａ，Ａ′の軸方向で入力部材Ｉの全体幅よりも小幅に形成される。更に入力部材Ｉには、支持壁部Ｉｓの両外側面に隣接して円形の段付き孔状に形成される一対の取付孔Ｉｈが、入力部材Ｉの両外側面に各々開口するように形成され、両取付孔Ｉｈの内周壁にカバー部Ｃ，Ｃ′の外周部が各々取付けられる。   Next, a mounting structure of the pinion shaft PS to the input member I will be described with reference to FIGS. The input member I has an annular support wall portion Is for supporting a pinion shaft PS as a pinion support portion, which is integrally protruded from the inner peripheral portion over the entire circumference. , A 'are formed smaller in width in the axial direction than the entire width of the input member I. Further, in the input member I, a pair of mounting holes Ih formed in the shape of a circular stepped hole adjacent to both outer surfaces of the support wall portion Is are formed so as to open on both outer surfaces of the input member I, respectively. Then, the outer peripheral portions of the cover portions C and C 'are respectively attached to the inner peripheral walls of both the mounting holes Ih.

ピニオンシャフトＰＳは、ピニオンシャフトＰＳの両端部がそれぞれ取付体Ｔを介して入力部材Ｉの支持壁部Ｉｓに連結支持されており、取付体Ｔには、ピニオンシャフトＰＳの端部を全周に亘って嵌合、保持し得る保持孔Ｔｈが形成される。また支持壁部Ｉｓの内周面には、支持壁部Ｉｓの、一方のカバー部Ｃ側の側面に開口部を有して出力軸Ａ，Ａ′軸方向に延びる横断面コ字状の取付溝Ｉａが凹設されており、取付溝Ｉａには、これの上記開口部より直方体状の取付体Ｔが挿入される。   In the pinion shaft PS, both ends of the pinion shaft PS are connected to and supported by the support wall portion Is of the input member I via the attachment T, and the end of the pinion shaft PS is attached to the entire periphery of the attachment T. A holding hole Th that can fit and hold over the entirety is formed. The support wall portion Is has an opening on the side surface on one cover portion C side of the support wall portion Is on the inner peripheral surface of the support wall portion Is and has a U-shaped cross section extending in the axial direction of the output shafts A and A '. A groove Ia is recessed, and a rectangular parallelepiped mounting body T is inserted into the mounting groove Ia through the opening.

取付体Ｔは、これを支持壁部Ｉｓの取付溝Ｉａに挿入された状態で一方のカバー部Ｃの外周部を後述する如く入力部材Ｉの取付孔Ｉｈに圧入及び溶接することにより、入力部材Ｉに固定される。また取付体ＴとピニオンＰの大径側端面との間には、その間の相対回転を許容する環状のスラストワッシャ１５が介装される。   The mounting member T is inserted into the mounting groove Ia of the support wall portion Is, and the outer peripheral portion of one of the cover portions C is press-fitted and welded into a mounting hole Ih of the input member I as described later, so that the input member Fixed to I. An annular thrust washer 15 that allows relative rotation therebetween is interposed between the attachment body T and the large-diameter end face of the pinion P.

上記したようなピニオンシャフトＰＳの入力部材Ｉへの取付構造によれば、ピニオンシャフトＰＳの端部を該端部の全周に亘り嵌合保持させたブロック状の取付体Ｔを介して、ピニオンシャフトＰＳを入力部材Ｉの取付溝Ｉａに容易且つ強固に連結固定できるため、入力部材ＩにピニオンシャフトＰＳ支持のための貫通孔を特別に形成することなく、また組立作業性を低下させることなく、ピニオンシャフトＰＳを入力部材Ｉに対し高い強度を以て連結支持させることができる。しかも本実施形態では、サイドギヤＳの外側を覆うカバー部Ｃが取付体Ｔに対する抜け止め固定手段を兼ねることで構造簡素化が図られる。   According to the mounting structure of the pinion shaft PS to the input member I as described above, the pinion shaft PS is connected to the pinion through the block-shaped mounting body T fitted and held over the entire periphery of the end. Since the shaft PS can be easily and firmly connected and fixed to the mounting groove Ia of the input member I, the through hole for supporting the pinion shaft PS is not particularly formed in the input member I, and the assembling workability is not reduced. The pinion shaft PS can be connected and supported to the input member I with high strength. Moreover, in the present embodiment, the structure is simplified by the fact that the cover portion C that covers the outside of the side gear S also functions as a retaining and fixing means for the attachment body T.

かくして、ピニオンシャフトＰＳの両端部が取付体Ｔを介して入力部材Ｉに連結支持された状態では、ピニオンシャフトＰＳに回転自在に支持されるピニオンＰの大径側端面と、入力部材Ｉの内周面との間には半径方向の間隙１０が形成される。従って、間隙１０には潤滑油が溜まり易くなるため、間隙１０に臨むピニオンＰの端部やその周辺部の焼付き防止に有効である。   Thus, in a state where both ends of the pinion shaft PS are connected and supported by the input member I via the attachment body T, the large-diameter end surface of the pinion P rotatably supported by the pinion shaft PS and the inside of the input member I A radial gap 10 is formed between the outer peripheral surface and the peripheral surface. Accordingly, the lubricating oil easily accumulates in the gap 10, which is effective for preventing seizure of the end of the pinion P facing the gap 10 and its peripheral portion.

ところで、上記した一方のカバー部Ｃの側壁部Ｃｓは、出力軸Ａ，Ａ′の軸方向外方から見た側面視で（即ち図２で見て）ピニオンＰと重なる領域を含む第１の所定領域でサイドギヤＳの背面を覆う油保持部７を備えており、更に上記側面視でピニオンＰと重ならない第２の所定領域において、サイドギヤＳの背面をデフケースＤＣ外に露出させる肉抜き部８と、油保持部７から入力部材Ｉの周方向に離間し且つ入力部材Ｉの半径方向に延びてボス部Ｃｂ及び入力部材Ｉ間を連結する連結腕部９とを併せ持つ構造となっている。換言すれば、カバー部Ｃの基本的に円板状をなす側壁部Ｃｓは、そこに切欠き状をなす肉抜き部８が周方向に間隔をおいて複数形成されることで、肉抜き部８を周方向に挟んで一方側に油保持部７が、他方側に連結腕部９がそれぞれ形成される構造形態となっている。   Incidentally, the first side wall portion Cs of the one cover portion C includes a region overlapping with the pinion P in a side view (that is, as viewed in FIG. 2) when viewed from the axially outer side of the output shafts A and A ′. An oil holding portion 7 that covers the back surface of the side gear S in a predetermined region, and a lightening portion 8 that exposes the back surface of the side gear S outside the differential case DC in a second predetermined region that does not overlap with the pinion P in the side view. And a connecting arm portion 9 that is spaced apart from the oil holding portion 7 in the circumferential direction of the input member I and extends in the radial direction of the input member I to connect the boss portion Cb and the input member I. In other words, the basically disk-shaped side wall portion Cs of the cover portion C is formed by forming a plurality of cutout-shaped lightening portions 8 at intervals in the circumferential direction. An oil holding portion 7 is formed on one side and a connecting arm portion 9 is formed on the other side, with the circumferential side of the oil holding portion 8 interposed therebetween.

このようなカバー部Ｃの側壁部Ｃｓの構造形態、特に油保持部７により、入力部材Ｉの回転による遠心力で径方向外方側に移動しようとする潤滑油を、油保持部７と入力部材Ｉとで覆われた空間に滞留させ易くなり、ピニオンＰ及びピニオンＰの周辺部に潤滑油を保持し易くすることができる。その上、カバー部Ｃが上記肉抜き部８を備えることで、肉抜き部８を通してデフケースＤＣの内外に潤滑油を流通させることができるため、潤滑油が適度に交換・冷却されて、油劣化防止に効果的である。また、デフケースＤＣ内に多量の潤滑油を閉じ込めておく必要はない上、肉抜き部８の形成分だけカバー部Ｃ自体が軽くなるため、それだけ差動装置Ｄの軽量化が図られる。   With such a configuration of the side wall portion Cs of the cover portion C, in particular, the oil holding portion 7 allows the lubricating oil that is to move radially outward due to the centrifugal force generated by the rotation of the input member I to be input to the oil holding portion 7. The lubricating oil can be easily retained in the space covered with the member I, and the pinion P and the peripheral portion of the pinion P can be easily retained. In addition, since the cover C is provided with the lightening portion 8, the lubricating oil can be circulated through the lightening portion 8 into and out of the differential case DC. It is effective for prevention. Further, it is not necessary to confine a large amount of lubricating oil in the differential case DC, and the cover portion C itself becomes lighter by the thickness of the lightening portion 8, so that the weight of the differential device D can be reduced accordingly.

尚、肉抜き部８は、本実施形態では側壁部Ｃｓの外周端側が開放した切欠き状に形成されるが、その外周端側が開放されない貫通孔状に形成してもよい。   In the present embodiment, the lightening portion 8 is formed in a cutout shape in which the outer peripheral end of the side wall portion Cs is open, but may be formed in a through-hole shape in which the outer peripheral end is not open.

また図３からも明らかなように、本実施形態では、他方のカバー部Ｃ′においても、側壁部Ｃｓに一方のカバー部Ｃと同様に肉抜き部８が形成される。尚、カバー部Ｃ，Ｃ′における肉抜き部８（従って油保持部７及び連結腕部９）の形態は種々の変形例が考えられ、図２，図３の実施形態に限定されない。   As is clear from FIG. 3, in the present embodiment, the lightening portion 8 is also formed on the side wall portion Cs of the other cover portion C ′ as in the case of the one cover portion C. The form of the lightening portion 8 (accordingly, the oil holding portion 7 and the connecting arm portion 9) in the cover portions C and C 'is not limited to the embodiment shown in FIGS.

次に図４及び図５を併せて参照して、入力部材Ｉにカバー部Ｃ，Ｃ′を固定するための構造を具体的に説明する。   Next, a structure for fixing the cover portions C and C 'to the input member I will be specifically described with reference to FIGS.

入力部材Ｉには、前述のようにカバー部Ｃ，Ｃ′を支持壁部Ｉｓの外側面に隣接させるようにして取付けるための段付き孔状の取付孔Ｉｈが形成される。取付孔Ｉｈの内周壁は、カバー部Ｃ，Ｃ′の側壁部Ｃｓの外周部（即ち油保持部７及び連結腕部９の各外端部）を入力部材Ｉの軸方向に嵌合して溶接させる大径の被溶接部２１と、被溶接部２１よりも入力部材Ｉの半径方向内方側且つ軸方向内方側に在ってカバー部Ｃ，Ｃ′の上記外周部を圧入させる被圧入部２２と、被溶接部２１及び被圧入部２２間を接続してカバー部Ｃ，Ｃ′との間に上記圧入の際の被圧入部２２の変形を許容する空間２４を形成する接続面２３とを有している。   As described above, the input member I is formed with a stepped hole-shaped mounting hole Ih for mounting the cover portions C and C 'adjacent to the outer side surface of the support wall portion Is. The inner peripheral wall of the mounting hole Ih fits the outer peripheral portion of the side wall portion Cs of the cover portions C and C ′ (that is, the outer end portions of the oil holding portion 7 and the connecting arm portion 9) in the axial direction of the input member I. The large-diameter welded portion 21 to be welded and the outer peripheral portions of the cover portions C and C ′ which are located radially inward and axially inward of the input member I with respect to the welded portion 21 are press-fitted. A connection surface that connects the press-fitted portion 22 and the welded portion 21 and the press-fitted portion 22 to form a space 24 between the cover portions C and C ′ that allows the deformation of the press-fitted portion 22 during the press-fitting. 23.

そして、接続面２３の、被溶接部２１に連なる一端部は、被溶接部２１から半径方向外方側に延出しており、その延出部２３ａが上記空間２４に臨んでいる。しかも、空間２４と被圧入部２２の少なくとも一部とは、入力部材Ｉの回転中心から放射方向に見て互いにオーバラップする（即ち軸方向で同じ領域に位置する）ように配置される。   One end of the connection surface 23 that is continuous with the welded portion 21 extends radially outward from the welded portion 21, and the extended portion 23 a faces the space 24. Moreover, the space 24 and at least a part of the press-fitted portion 22 are arranged so as to overlap each other when viewed in the radial direction from the rotation center of the input member I (that is, located in the same region in the axial direction).

またカバー部Ｃ，Ｃ′の側壁部Ｃｓの外周部（即ち油保持部７及び連結腕部９の各外端部）には、入力部材Ｉの被溶接部２１に嵌合して溶接される大径部３１と、大径部３１の軸方向内端に段差面３３を介して連なり且つ被圧入部２２に圧入される小径部３２とが形成される。そして、被圧入部２２の軸方向外端２２ｏが段差面３３に当接又は近接（図示例では近接）している。   Further, the outer peripheral portions of the side wall portions Cs of the cover portions C and C ′ (that is, the outer ends of the oil holding portion 7 and the connecting arm portion 9) are fitted to and welded to the welded portions 21 of the input member I. A large-diameter portion 31 and a small-diameter portion 32 connected to the inner end of the large-diameter portion 31 in the axial direction via a step surface 33 and pressed into the press-fitted portion 22 are formed. The axially outer end 22o of the press-fitted portion 22 is in contact with or close to the step surface 33 (in the illustrated example, close).

さらに入力部材Ｉの接続面２３は、被圧入部２２の軸方向外端２２ｏの近傍部から半径方向外方に向かうにつれて段差面３３から徐々に離間する傾斜部２３ｂを有している。そして、傾斜部２３ｂと、上記した延出部２３ａとは、傾斜部２３ｂ及び延出部２３ａの半径方向外端側で横断面円弧状をなす中間湾曲部２３ｃを介して滑らかに連続している。尚、傾斜部２３ｂは、被圧入部２２の軸方向外端２２ｏを起点として、それから半径方向外方に向かうにつれて段差面３３から徐々に離間するように形成してもよい。   Further, the connection surface 23 of the input member I has an inclined portion 23b that gradually separates from the step surface 33 as going radially outward from a portion near the axially outer end 22o of the press-fitted portion 22. The inclined portion 23b and the above-mentioned extending portion 23a are smoothly continuous via an intermediate curved portion 23c having an arc-shaped cross section at the radially outer end side of the inclined portion 23b and the extending portion 23a. . Note that the inclined portion 23b may be formed so as to start from the axial outer end 22o of the press-fitted portion 22 and gradually separate from the step surface 33 as going outward in the radial direction.

また、入力部材Ｉの接続面２３と被圧入部２２との接続部には第１の面取りｒ１が形成され、第１の面取りｒ１に対応してカバー部Ｃ，Ｃ′の段差面３３には、第１の面取りｒ１を逃げるようにして第１の面取りｒ１に小間隙を介して対向する第１の凹部ｒ１′が形成される。またカバー部Ｃ，Ｃ′の内側面と小径部３２との接続部には第２の面取りｒ２が形成され、第２の面取りｒ２に対応して入力部材Ｉの被圧入部２２と支持壁部Ｉｓ外側面との接続部には、第２の面取りｒ２を逃げるようにして第２の面取りｒ２に小間隙を介して対向する第２の凹部ｒ２′が形成される。   Further, a first chamfer r1 is formed at a connection portion between the connection surface 23 of the input member I and the press-fitted portion 22, and a step surface 33 of the cover portions C and C 'is formed corresponding to the first chamfer r1. A first recess r1 'is formed to face the first chamfer r1 with a small gap so as to escape the first chamfer r1. Further, a second chamfer r2 is formed at a connection portion between the inner side surfaces of the cover portions C and C 'and the small diameter portion 32, and the press-fitted portion 22 of the input member I and the support wall portion correspond to the second chamfer r2. A second concave portion r2 'is formed at the connection portion with the Is outer surface so as to escape from the second chamfer r2 and to face the second chamfer r2 via a small gap.

次に、上記第１実施形態の作用について説明する。本実施形態の差動装置Ｄは、入力部材Ｉにエンジンから回転力を受けた場合に、ピニオンＰがピニオンシャフトＰＳ回りに自転しないで入力部材Ｉと共に入力部材Ｉの軸線Ｌ回りに公転するときは、左右のサイドギヤＳが同速度で回転駆動されて、駆動力が均等に左右の出力軸Ａ，Ａ′に伝達される。また、自動車の旋回走行等により左右の出力軸Ａ，Ａ′に回転速度差が生じるときは、ピニオンＰが自転しつつ公転することで、ピニオンＰから左右のサイドギヤＳに対して差動回転を許容しつつ回転駆動力が伝達される。以上は、従来周知の差動装置の作動と同様である。   Next, the operation of the first embodiment will be described. The differential device D according to the present embodiment is configured such that when the input member I receives a rotational force from the engine, the pinion P revolves around the axis L of the input member I together with the input member I without rotating around the pinion shaft PS. The left and right side gears S are driven to rotate at the same speed, and the driving force is evenly transmitted to the left and right output shafts A and A '. When a rotational speed difference occurs between the left and right output shafts A and A 'due to turning of the automobile or the like, the pinion P revolves while rotating, so that the pinion P performs differential rotation with respect to the left and right side gears S. The rotational driving force is transmitted while being allowed. The above is the same as the operation of the conventionally known differential.

そして、自動車の前進走行状態でエンジンの動力が差動装置Ｄを介して左右の出力軸Ａ，Ａ′に伝達される場合に、デフケースＤＣの正転方向（図２、図３の太字矢印方向）の回転に伴いミッションケース１内の各所で潤滑油が勢いよく飛散するが、飛散した潤滑油の一部は、カバー部Ｃ，Ｃ′の内側に肉抜き部８から流入し、これにより、ピニオンＰとサイドギヤＳとの噛合部やピニオンＰの摺動部を効果的に潤滑できる。   When the power of the engine is transmitted to the left and right output shafts A and A 'via the differential device D in the forward running state of the automobile, the forward direction of the differential case DC (the bold arrow direction in FIGS. 2 and 3) ), The lubricating oil scatters vigorously at various places in the transmission case 1, but a part of the scattered lubricating oil flows into the inside of the cover portions C and C ′ from the lightening portion 8, whereby The meshing portion between the pinion P and the side gear S and the sliding portion of the pinion P can be effectively lubricated.

ところで本実施形態において、カバー部Ｃ，Ｃ′の側壁部Ｃｓの外周部（即ち油保持部７及び連結腕部９の各外端部）は、入力部材Ｉの取付孔Ｉｈに圧入及び溶接により取付、固定されるが、その取付固定作業は、予めピニオンシャフトＰＳの端部にセットした取付体Ｔを入力部材Ｉの支持壁部Ｉｓの取付溝Ｉａに装入、保持させた状態で行われる。   In the present embodiment, the outer peripheral portions of the side wall portions Cs of the cover portions C and C ′ (that is, the outer ends of the oil holding portion 7 and the connecting arm portion 9) are press-fitted into the mounting holes Ih of the input member I and welded. The mounting member T is mounted and fixed. The mounting and fixing operation is performed in a state where the mounting body T set in advance at the end of the pinion shaft PS is inserted and held in the mounting groove Ia of the support wall portion Is of the input member I. .

取付固定作業について、次に具体的に説明する。先ず、入力部材Ｉの取付孔Ｉｈの被圧入部２２にカバー部Ｃ，Ｃ′の小径部３２を軸方向に圧入させると共に、同取付孔Ｉｈの被溶接部２１に同カバー部Ｃ，Ｃ′の大径部３１を嵌合させる。次いで、嵌合部、即ち被溶接部２１と大径部３１との突き当て当接部を、カバー部Ｃ，Ｃ′の外側方から突き当て溶接ｗする。   Next, the mounting and fixing operation will be specifically described. First, the small-diameter portions 32 of the cover portions C and C 'are axially pressed into the press-fitted portions 22 of the mounting holes Ih of the input member I, and the cover portions C and C' are fitted into the welded portions 21 of the mounting holes Ih. Large diameter portion 31 is fitted. Next, the fitting portion, that is, the butt contact portion between the welded portion 21 and the large diameter portion 31 is butt-welded w from outside the cover portions C and C ′.

溶接作業は、例えば、図４及び図５に示すようにカバー部Ｃ，Ｃ′の外側方に配備される溶接用レーザトーチＧから上記突き当て当接部の外端に向けてレーザを照射し且つ入力部材Ｉを入力部材Ｉの回転軸線Ｌ回りに緩やかに回転させることによって行われる。その際にレーザのエネルギにより、取付孔Ｉｈの被溶接部２１とカバー部Ｃ，Ｃ′の大径部３１とを互いに突き当て溶接ｗすることができる。尚、この場合、両カバー部Ｃ，Ｃ′の外側方に一対のレーザトーチＧをそれぞれ配置して入力部材Ｉを回転させるようにすれば、入力部材Ｉの左右一対の取付孔Ｉｈの被溶接部２１に左右のカバー部Ｃ，Ｃ′の大径部３１を同時に突き当て溶接ｗすることができるため、溶接作業効率が高められる。
In the welding operation, for example, as shown in FIGS. 4 and 5, a laser is irradiated from a welding laser torch G provided outside the covers C and C 'toward the outer end of the abutting contact portion. Accordingly performed thereby slowly rotate the rotation axis L about the input member I input member I. At this time, the welded portion 21 of the mounting hole Ih and the large-diameter portion 31 of the cover portions C and C ′ can be butt-welded to each other by the energy of the laser. In this case, if the input member I is rotated by disposing a pair of laser torches G on the outer sides of the two cover portions C and C ', the welded portions of the pair of left and right mounting holes Ih of the input member I can be obtained. Since the large diameter portions 31 of the right and left cover portions C and C 'can be simultaneously butt-welded to 21, the welding operation efficiency is improved.

そして、本実施形態では、入力部材Ｉの取付孔Ｉｈの内周壁が、カバー部Ｃ，Ｃ′の外周部（即ち油保持部７及び連結腕部９の各外端部）を入力部材Ｉの軸方向に嵌合して溶接させる大径の被溶接部２１と、被溶接部２１よりも入力部材Ｉの半径方向内方側で且つ軸方向内方側に在ってカバー部Ｃ，Ｃ′の外周部を圧入させる被圧入部２２と、被溶接部２１及び被圧入部２２間を接続してカバー部Ｃ，Ｃ′との間に圧入の際の被圧入部２２の変形（従って変位）を許容する空間２４を形成する接続面２３とを有している。そのため、上記圧入の際に入力部材Ｉの被圧入部２２周辺が半径方向に僅かに撓み変形することが許容され、被圧入部２２周辺に圧入時に生じる機械的な歪が緩和されるから、歪の影響で入力部材Ｉ及びカバー部Ｃ，Ｃ′、延いては差動装置Ｄ全体の組立精度が低下するのを効果的に防止可能となる。   In the present embodiment, the inner peripheral wall of the mounting hole Ih of the input member I is connected to the outer peripheral portions of the cover portions C and C ′ (that is, the outer ends of the oil holding portion 7 and the connecting arm portion 9). A large-diameter welded portion 21 to be fitted and welded in the axial direction, and cover portions C and C 'located radially inward of the input member I and axially inward of the input member I with respect to the welded portion 21. Of the press-fitted portion 22 for press-fitting the outer peripheral portion thereof, and the deformation (accordingly, displacement) of the press-fitted portion 22 at the time of press-fitting between the welded portion 21 and the press-fitted portion 22 to press-fit between the cover portions C and C ′. And a connection surface 23 that forms a space 24 that allows Therefore, the periphery of the press-fitted portion 22 of the input member I is allowed to slightly bend and deform in the radial direction during the press-fitting, and the mechanical strain generated at the time of press-fitting around the press-fitted portion 22 is reduced. Can effectively prevent the assembling accuracy of the input member I and the cover portions C and C ', and consequently the entire differential device D, from deteriorating.

また、差動装置Ｄにおける入力部材Ｉの配置形態等（例えば本実施形態のように入力歯部Ｉｇをヘリカルギヤとしたこと）によっては、回転中の入力部材Ｉに対して駆動源側からスラスト荷重が少なからず作用する場合がある。そのような場合でも、本実施形態では取付孔Ｉｈの接続面２３の、被溶接部２１に連なる一端部は、被溶接部２１から半径方向外方側に延出しているので、延出部２３ａ側に上記スラスト荷重に因る応力を分散させることができる。その結果、入力部材Ｉとカバー部Ｃ，Ｃ′との突き当て溶接部ｗに応力集中が生じるのを効果的に防止できるから、応力集中による溶接部ｗの耐久性低下が回避可能となる。しかも、上記空間２４と被圧入部２２の少なくとも一部とは、入力部材Ｉの回転中心から放射方向に見て互いにオーバラップする（即ち軸方向で同じ領域に位置する）ように配置されるため、圧入の際に入力部材Ｉの被圧入部２２周辺が半径方向外方に一層撓み変形し易くなり、圧入による歪が効果的に緩和され、歪の影響に因る入力部材Ｉ及びカバー部Ｃ，Ｃ′の組立精度低下が効果的に抑制される。
Further, depending on the arrangement of the input member I in the differential device D (for example, the input tooth portion Ig is formed as a helical gear as in the present embodiment), the thrust load from the drive source side to the rotating input member I is changed . May act to some extent. Even in such a case, in the present embodiment, one end of the connection surface 23 of the mounting hole Ih connected to the welded portion 21 extends radially outward from the welded portion 21. The stress caused by the thrust load can be dispersed on the side. As a result, stress concentration can be effectively prevented from being generated in the butt welding portion w between the input member I and the cover portions C and C ', so that a decrease in the durability of the welding portion w due to the stress concentration can be avoided. Moreover, the space 24 and at least a part of the press-fitted portion 22 are arranged so as to overlap with each other when viewed in the radial direction from the rotation center of the input member I (that is, located in the same region in the axial direction). During the press-fitting, the periphery of the press-fitted portion 22 of the input member I is more likely to bend and deform radially outward, the strain due to the press-fitting is effectively reduced, and the input member I and the cover C due to the influence of the strain are reduced. , C ′ is effectively suppressed.

また、本実施形態では、カバー部Ｃ，Ｃ′の側壁部Ｃｓの外周部（即ち油保持部７及び連結腕部９の各外端部）には、入力部材Ｉの被溶接部２１に嵌合して溶接される大径部３１と、大径部３１の軸方向内端に段差面３３を介して連なり且つ被圧入部２２に圧入される小径部３２とが形成されるが、被圧入部２２の外端２２ｏが段差面３３に当接又は近接している上、接続面２３が、被圧入部２２の外端２２ｏ又は外端２２ｏの近傍部から半径方向外方に向かうにつれて段差面３３から徐々に離間する傾斜部２３ｂを有している。これにより、被圧入部２２と小径部３２との圧入接触面積を十分確保しながら、入力部材Ｉの被圧入部２２周辺を半径方向外方へ一層容易に撓み変形させることが可能となる。   Further, in the present embodiment, the outer peripheral portion of the side wall portion Cs of the cover portions C and C ′ (that is, the outer ends of the oil holding portion 7 and the connecting arm portion 9) is fitted to the welded portion 21 of the input member I. A large-diameter portion 31 to be welded together and a small-diameter portion 32 connected to the inner end in the axial direction of the large-diameter portion 31 via a step surface 33 and press-fitted into the press-fitted portion 22 are formed. The outer end 22o of the portion 22 is in contact with or close to the step surface 33, and the connecting surface 23 is radially outward from the outer end 22o of the press-fitted portion 22 or the vicinity of the outer end 22o. It has an inclined portion 23b that is gradually separated from 33. Thus, the area around the press-fitted portion 22 of the input member I can be more easily bent outward in the radial direction while ensuring a sufficient press-fit contact area between the press-fitted portion 22 and the small-diameter portion 32.

而して、本実施形態の差動装置Ｄにおいて、サイドギヤＳは、出力軸Ａ，Ａ′に接続される軸部Ｓｊと、出力軸Ａ，Ａ′の軸線Ｌと直交する扁平なリング板状に形成されて、軸部Ｓｊと該軸部Ｓｊから入力部材Ｉの半径方向外方に離間したサイドギヤ歯部Ｓｇとの間を一体に接続する中間壁部Ｓｗとを有しており、その上、中間壁部Ｓｗは、それの半径方向幅ｔ１がピニオンＰの最大直径ｄ１よりも長くなるよう形成されている。このため、サイドギヤＳの歯数Ｚ１をピニオンＰの歯数Ｚ２よりも十分大きく設定し得るようにサイドギヤＳをピニオンＰに対し十分大径化できることから、ピニオンＰからサイドギヤＳへのトルク伝達時におけるピニオンシャフトＰＳの荷重負担を軽減できてピニオンシャフトＰＳの有効直径ｄ２の小径化、延いてはピニオンＰの、出力軸Ａ，Ａ′軸方向での幅狭化を図ることができる。   Thus, in the differential device D of the present embodiment, the side gear S has a flat ring-shaped plate Sj connected to the output shafts A and A 'and a flat ring plate orthogonal to the axis L of the output shafts A and A'. And an intermediate wall portion Sw that integrally connects the shaft portion Sj and a side gear tooth portion Sg that is spaced apart from the shaft portion Sj in the radial direction of the input member I. The intermediate wall portion Sw is formed such that its radial width t1 is longer than the maximum diameter d1 of the pinion P. Therefore, the side gear S can have a sufficiently large diameter with respect to the pinion P so that the number of teeth Z1 of the side gear S can be set to be sufficiently larger than the number of teeth Z2 of the pinion P. Therefore, when transmitting torque from the pinion P to the side gear S, The load on the pinion shaft PS can be reduced, and the effective diameter d2 of the pinion shaft PS can be reduced, and the pinion P can be narrowed in the output shaft A and A 'axis directions.

また上記のようにピニオンシャフトＰＳの荷重負担が軽減されると共に、サイドギヤＳにかかる反力が低下し、その上、サイドギヤＳの中間壁部Ｓｗ又は歯部Ｓｇの背面がカバー側壁部Ｃｓに支持されるので、サイドギヤＳの中間壁部Ｓｗを薄肉化してもサイドギヤＳの必要な剛性強度は確保することが容易であり、即ち、サイドギヤＳに対する支持剛性を確保しつつサイドギヤ中間壁部Ｓｗを十分に薄肉化することが可能となる。また、本実施形態では、上記のように小径化を可能としたピニオンシャフトＰＳの有効直径ｄ２よりもサイドギヤ中間壁部Ｓｗの最大肉厚ｔ２が更に小さく形成されるため、サイドギヤ中間壁部Ｓｗの更なる薄肉化が達成可能となる。しかもカバー側壁部Ｃｓが、外側面を出力軸Ａ，Ａ′の軸線Ｌと直交する平坦面とした板状に形成されることで、カバー側壁部Ｃｓ自体の薄肉化も達成される。
Together with the load bearing of the pinion shaft P S as described above is reduced, the reaction force is reduced according to the side gears S, on which the back of the intermediate wall portion Sw or teeth Sg side gears S is the cover side wall portion Cs Since it is supported, even if the intermediate wall portion Sw of the side gear S is thinned, it is easy to secure the necessary rigidity of the side gear S. That is, the side gear intermediate wall portion Sw is secured while securing the supporting rigidity for the side gear S. It is possible to reduce the thickness sufficiently. Further, in the present embodiment, the maximum thickness t2 of the side gear intermediate wall portion Sw is formed to be smaller than the effective diameter d2 of the pinion shaft PS whose diameter can be reduced as described above. Further thinning can be achieved. Moreover, since the cover side wall portion Cs is formed in a plate shape whose outer surface is a flat surface orthogonal to the axis L of the output shafts A and A ', the thickness of the cover side wall portion Cs itself is also reduced.

それらの結果、差動装置Ｄは、従来装置と同程度の強度（例えば静ねじり荷重強度）や最大トルク伝達量を確保しながら、全体として出力軸Ａ，Ａ′の軸方向で十分に幅狭化することができる。これにより、差動装置Ｄの周辺のレイアウト上の制約が多い伝動系に対しても差動装置Ｄを、高い自由度を以て無理なく容易に組込み可能となり、また伝動系を小型化する上で頗る有利となる。   As a result, the differential device D is sufficiently narrow as a whole in the axial direction of the output shafts A and A 'while securing the same strength (for example, static torsional load strength) and the maximum torque transmission amount as the conventional device. Can be As a result, the differential device D can be easily and easily incorporated with a high degree of freedom into a transmission system having many layout restrictions around the differential device D, and it is extremely difficult to reduce the size of the transmission system. This is advantageous.

ところで、上記した第１実施形態では、ピニオン支持部（差動ギヤ支持部）として長いピニオンシャフトＰＳを用いるものを示したが、図６に示す本発明の第２実施形態では、ピニオンＰの大径側の端面に同軸に一体に結合された支持軸部ＰＳ′でピニオン支持部（差動ギヤ支持部）が構成される。この構成によれば、ピニオンシャフトＰＳを嵌合させる貫通孔をピニオンＰに設ける必要はなくなるため、それだけピニオンＰを小径化（軸方向幅狭化）できて、差動装置Ｄの出力軸Ａ，Ａ′軸方向での扁平化を図ることができる。即ち、ピニオンシャフトＰＳがピニオンＰを貫通する場合、ピニオンＰにはピニオンシャフト径に対応するサイズの貫通孔を形成する必要があるが、ピニオンＰ端面に支持軸部ＰＳ′を一体化した場合には、支持軸部ＰＳ′の径に依存することなくピニオンＰの小径化（軸方向幅狭化）が可能となる。   By the way, in the above-described first embodiment, the long pinion shaft PS is used as the pinion support (differential gear support), but in the second embodiment of the present invention shown in FIG. A pinion support (differential gear support) is constituted by a support shaft PS 'coaxially and integrally connected to the radial end surface. According to this configuration, it is not necessary to provide a through-hole for fitting the pinion shaft PS in the pinion P. Therefore, the diameter of the pinion P can be reduced accordingly (axial width narrowing), and the output shafts A, Flattening in the A'-axis direction can be achieved. That is, when the pinion shaft PS penetrates the pinion P, it is necessary to form a through hole having a size corresponding to the diameter of the pinion shaft in the pinion P. However, when the support shaft portion PS ′ is integrated with the end surface of the pinion P, Allows the pinion P to be reduced in diameter (axial width narrowing) without depending on the diameter of the support shaft portion PS ′.

また本第２実施形態では、支持軸部ＰＳ′の外周面と、支持軸部ＰＳ′が挿入される取付体Ｔの保持孔Ｔｈ内周面との間に、その間の相対回転を許容する軸受としての軸受ブッシュ１２が介挿される。尚、軸受としては、ニードルベアリング等の軸受を使用してもよい。尚また、軸受を省略して、支持軸部ＰＳ′を取付体Ｔの保持孔Ｔｈに直接嵌合させてもよい。   In the second embodiment, a bearing that allows relative rotation between the outer peripheral surface of the support shaft portion PS ′ and the inner peripheral surface of the holding hole Th of the mounting body T into which the support shaft portion PS ′ is inserted. The bearing bush 12 is inserted. Note that a bearing such as a needle bearing may be used as the bearing. In addition, the bearing may be omitted, and the support shaft portion PS 'may be directly fitted into the holding hole Th of the mounting body T.

次に図７及び図８を参照して、本発明の第３実施形態について説明する。この第３実施形態では、デフケースＤＣＸ及びデフケースＤＣＸの内部に収納される差動機構ＤＭＸが、第１，第２実施形態のデフケースＤＣ及び差動機構ＤＭと具体的構造及び機能が異なる。   Next, a third embodiment of the present invention will be described with reference to FIGS. In the third embodiment, the differential case DCX and the differential mechanism DMX housed inside the differential case DCX are different in specific structure and function from the differential case DC and the differential mechanism DM of the first and second embodiments.

即ち、差動装置Ｄは、入力部としての被動プーリＩｐを外周に一体に有する短円筒状の入力部材ＩＸ（第１回転部材）と、エンジンから被動プーリＩｐを経て入力部材ＩＸに作用する回転力を左右一対の出力軸Ａ，Ａ′に分配して伝達する差動機構ＤＭＸと、入力部材ＩＸに結合されて該入力部材ＩＸの軸方向両端の開放端部をそれぞれ塞ぐ円板状の左右一対のカバー部Ｃ，Ｃ′とを備える。そして、入力部材ＩＸおよびカバー部Ｃ，Ｃ′によりデフケースＤＣＸが構成され、デフケースＤＣＸ内に差動機構ＤＭＸが配設される。デフケースＤＣＸのミッションケース１への取付構造は、第１実施形態と同様である。尚、本実施形態において、入力部としての被動プーリＩｐに代えて、第１実施形態のような入力歯部Ｉｇを入力部材ＩＸの外周に設けてもよい。   That is, the differential device D includes a short cylindrical input member IX (first rotating member) integrally having a driven pulley Ip as an input unit on the outer periphery, and a rotation acting on the input member IX from the engine via the driven pulley Ip. A differential mechanism DMX that distributes and transmits a force to a pair of left and right output shafts A and A ′, and a disk-shaped left and right that is coupled to the input member IX and closes open ends at both axial ends of the input member IX, respectively. And a pair of cover portions C and C '. Then, a differential case DCX is constituted by the input member IX and the cover portions C and C ', and a differential mechanism DMX is provided in the differential case DCX. The structure for attaching the differential case DCX to the transmission case 1 is the same as in the first embodiment. In this embodiment, instead of the driven pulley Ip as an input unit, an input tooth Ig as in the first embodiment may be provided on the outer periphery of the input member IX.

而して、入力部材ＩＸおよびカバー部Ｃ，Ｃ′間の結合構造は、第１，第２実施形態における入力部材Ｉおよびカバー部Ｃ，Ｃ′間の結合構造と基本的に同じであって、溶接と圧入とを併用している。従って、入力部材ＩＸおよびカバー部Ｃ，Ｃ′間の具体的な結合構造については、各構成要素に第１，第２実施形態の対応する構成要素と同じ参照符号を付すに留め、これ以上の構造説明を省略する。尚、本実施形態では、入力部材ＩＸの内周部に左右一対の支持壁部Ｉｓ，Ｉｓが互いに間隔をおいて且つ全周に亘って突設されており、それら支持壁部Ｉｓ，Ｉｓの外側面にカバー部Ｃ，Ｃ′の内側面がそれぞれ当接している。   Thus, the coupling structure between the input member IX and the cover portions C and C 'is basically the same as the coupling structure between the input member I and the cover portions C and C' in the first and second embodiments. , Welding and press fitting are used together. Therefore, as for the specific coupling structure between the input member IX and the cover parts C and C ', the same reference numerals as those of the corresponding components in the first and second embodiments are given to the respective components, and no further description will be given. Description of the structure is omitted. In the present embodiment, a pair of left and right support walls Is, which are provided on the inner periphery of the input member IX, are spaced from each other and protrude over the entire circumference, and the support walls Is, Is The inner surfaces of the cover portions C and C 'are in contact with the outer surfaces.

また、差動機構ＤＭＸは、第１回転軸線Ｘ１上の主軸部１０５ａ、第１回転軸線Ｘ１から偏心した第２回転軸線Ｘ２上の第１偏心軸部１０５ｂ、第２回転軸線Ｘ２とは逆側に第１回転軸線Ｘ１から偏心した第３回転軸線Ｘ３上の第２偏心軸部１０５ｃを有していて、第１，第２偏心軸部１０５ｂ，１０５ｃが第１回転軸線Ｘ１周りに相互に１８０度ずれた位相で公転し得る偏心シャフト１０５と、入力部材ＩＸの一方の支持壁部Ｉｓの内周端に形成された内歯Ｉｂと噛み合う外歯１０６ａを有していて第１偏心軸部１０５ｂ上で自転しながら第１回転軸線Ｘ１周りに公転し得る、入力部材ＩＸよりも小径の第２回転部材１０６と、第２回転部材１０６の外歯１０６ａと同じモジュールの外歯１０７ａを有して第２回転部材１０６の一側に隣接配置され、第２偏心軸部１０５ｃ上で自転しながら第１回転軸線Ｘ１周りに公転し得る第３回転部材１０７と、第１回転軸線Ｘ１周りに回転可能で第２，第３回転部材１０６，１０７の外周に配置され、第２回転部材１０６の自転を第３回転部材１０７に伝達すべく、それの内周に形成された内歯１０８ａを第２，第３回転部材１０６，１０７の外歯１０６ａ，１０７ａと噛み合わせる、第２，第３回転部材１０６，１０７よりも大径の第４回転部材１０８と、第３回転部材１０７の一側に隣接配置され、第３回転部材１０７の自転および公転を受けて第１回転軸線Ｘ１周りに回転する第５回転部材１０９とを備えている。
The differential mechanism DMX has a main shaft portion 105a on the first rotation axis X1, a first eccentric shaft portion 105b on a second rotation axis X2 eccentric from the first rotation axis X1, and an opposite side to the second rotation axis X2. Has a second eccentric shaft portion 105c eccentric from the first rotation axis X1 on the third rotation axis X3, and the first and second eccentric shaft portions 105b and 105c are mutually 180 degrees around the first rotation axis X1. A first eccentric shaft portion 105b having an eccentric shaft 105 capable of revolving at a phase shifted by an angle and external teeth 106a meshing with internal teeth Ib formed at an inner peripheral end of one support wall portion Is of the input member IX; It has a second rotating member 106 smaller in diameter than the input member IX , which can revolve around the first rotating axis X1 while rotating on its top, and external teeth 107a of the same module as the external teeth 106a of the second rotating member 106. Adjacent to one side of the second rotating member 106 A third rotating member 107 which is arranged and revolves around the first rotation axis X1 while rotating on the second eccentric shaft portion 105c; and a second and third rotating members 106 rotatable around the first rotation axis X1. In order to transmit the rotation of the second rotating member 106 to the third rotating member 107, the internal teeth 108 a formed on the inner periphery of the second rotating member 106 are arranged outside the second and third rotating members 106 and 107. A fourth rotating member 108, which is larger in diameter than the second and third rotating members 106 and 107, meshes with the first and second rotating members 106a and 107a. A fifth rotation member 109 that rotates around the first rotation axis X1 in response to the revolution.

そして、偏心シャフト１０５の主軸部１０５ａに左右一方の出力軸Ａがスプライン接合されるとともに、第５回転部材１０９の軸部１０９ｂに左右他方の出力軸Ａ′がスプライン接合される。その際、第２回転部材１０６は第１ベアリング１１１を介して偏心シャフト１０５の第１偏心軸部１０５ｂに嵌合し、第３回転部材１０７は第２ベアリング１１２を介して偏心シャフト１０５の第２偏心軸部１０５ｃに嵌合する。また、偏心シャフト１０５の主軸部１０５ａと一方のカバー部Ｃとの間には第３ベアリング１１３が介装され、第５回転部材１０９の軸部１０９ｂと他方のカバー部Ｃ′との間には第４ベアリング１１４が介装される。   One of the left and right output shafts A is spline-joined to the main shaft portion 105 a of the eccentric shaft 105, and the other left and right output shaft A ′ is spline-joined to the shaft portion 109 b of the fifth rotating member 109. At this time, the second rotating member 106 is fitted to the first eccentric shaft portion 105b of the eccentric shaft 105 via the first bearing 111, and the third rotating member 107 is connected to the second eccentric shaft 105 of the eccentric shaft 105 via the second bearing 112. The eccentric shaft 105c is fitted. Further, a third bearing 113 is interposed between the main shaft portion 105a of the eccentric shaft 105 and one cover portion C, and a third bearing 113 is provided between the shaft portion 109b of the fifth rotating member 109 and the other cover portion C '. The fourth bearing 114 is interposed.

また第３回転部材１０７と第５回転部材１０９とは、本実施形態では、両者の対向面に形成された第３回転部材１０７の６波のトロコイド溝１０７ｂと第５回転部材１０９の４波のトロコイド溝１０９ａとの間に挟持した５個のボール１１０を介して相互に噛み合っている。   Further, in the present embodiment, the third rotating member 107 and the fifth rotating member 109 are formed by the trochoid grooves 107b of six waves of the third rotating member 107 formed on the opposing surfaces thereof and the four waves of the fifth rotating member 109. They are in mesh with each other via five balls 110 sandwiched between them and the trochoid groove 109a.

本第３実施形態の差動装置Ｄの差動機構ＤＭＸの作動を次に説明する。例えば、入力部材Ｉ（第１回転部材）を仮に固定して一方の出力軸Ａを回転させると、偏心シャフト１０５の主軸部１０５ａが回転して入力部材Ｉの内歯Ｉｂと噛み合う第２回転部材１０６が第１偏心軸部１０５ｂ上で自転しながら第１回転軸線Ｘ１周りに公転するが、第２回転部材１０６と第３回転部材１０７とは偏心シャフト１０５によって１８０度ずれた位相で公転し、また第２回転部材１０６の自転は第４回転部材１０８を介して第３回転部材１０７に伝達されるので、第２回転部材１０６の公転及び自転は、公転の位相が１８０度ずれるだけで第３回転部材１０７に伝達される。そして第３回転部材１０７の公転及び自転は、第３回転部材１０７に噛み合って第１回転軸線Ｘ１周りに回転可能な第５回転部材１０９に伝達されるから、第５回転部材１０９に接続された他方の出力軸Ａ′が一方の出力軸Ａとは異なる回転数で回転することになるが、差動装置Ｄ内部の各噛み合い部を等価のピッチ円で表したときの各回転部材のピッチ円半径を適切に定めることで、一方の出力軸Ａの回転数をｋとしたときに他方の出力軸Ａ′の回転数を−ｋとすることができる。そのため、この状態で入力部材Ｉをｎ回転させると、一方の出力軸Ａがｎ＋ｋ回転し他方の出力軸Ａ′がｎ−ｋ回転することになって等差動回転が可能となるので、差動装置として有効に機能させることできる。   Next, the operation of the differential mechanism DMX of the differential gear D according to the third embodiment will be described. For example, when the input member I (first rotating member) is temporarily fixed and one output shaft A is rotated, the main shaft portion 105a of the eccentric shaft 105 rotates to mesh with the internal teeth Ib of the input member I. 106 revolves around the first rotation axis X1 while rotating on the first eccentric shaft portion 105b, but the second rotation member 106 and the third rotation member 107 revolve at a phase shifted by 180 degrees by the eccentric shaft 105, In addition, since the rotation of the second rotating member 106 is transmitted to the third rotating member 107 via the fourth rotating member 108, the rotation and rotation of the second rotating member 106 are shifted only by 180 degrees in the third rotation. The power is transmitted to the rotating member 107. Then, the revolution and the rotation of the third rotating member 107 are transmitted to the fifth rotating member 109 which can mesh with the third rotating member 107 and can rotate around the first rotation axis X1, so that the third rotating member 107 is connected to the fifth rotating member 109. The other output shaft A 'rotates at a different rotation speed from the one output shaft A, but the pitch circle of each rotating member when each meshing portion inside the differential device D is represented by an equivalent pitch circle. By appropriately setting the radius, when the rotation speed of one output shaft A is k, the rotation speed of the other output shaft A ′ can be −k. Therefore, when the input member I is rotated n times in this state, one output shaft A rotates n + k and the other output shaft A ′ rotates n−k, so that equal differential rotation is possible. It can function effectively as a moving device.

ところで上記した特許文献２，３で例示したような従来の差動装置（特に入力部材内にピニオン（差動ギヤ）と、ピニオン（差動ギヤ）に噛合する一対のサイドギヤ（出力ギヤ）とを備えた従来の差動装置）では、通常、サイドギヤ（出力ギヤ）の歯数Ｚ１とピニオン（差動ギヤ）の歯数Ｚ２として、例えば特許文献３に示される14×10、或いは16×10または13×９が用いられている。この場合、差動ギヤに対する出力ギヤの歯数比率Ｚ１／Ｚ２は、それぞれ1.4 、1.6 、1.44となっている。また従来の差動装置では、歯数Ｚ１，Ｚ２の、その他の組合わせとして、例えば15×10、17×10、18×10、19×10、または20×10となっているものも知られており、この場合の歯数比率Ｚ１／Ｚ２は、それぞれ1.5 、1.7 、1.8 、1.9 、2.0 となっている。   By the way, a conventional differential device as exemplified in the above-mentioned Patent Documents 2 and 3 (particularly, a pinion (differential gear) in an input member, and a pair of side gears (output gears) meshed with the pinion (differential gear)) In a conventional differential device provided with a gear, normally, the number of teeth Z1 of a side gear (output gear) and the number of teeth Z2 of a pinion (differential gear) are, for example, 14 × 10, 16 × 10, or 13 × 9 is used. In this case, the ratio of the number of teeth Z1 / Z2 of the output gear to the differential gear is 1.4, 1.6, and 1.44, respectively. Further, in a conventional differential device, there are known other combinations of the number of teeth Z1 and Z2, for example, 15 × 10, 17 × 10, 18 × 10, 19 × 10, or 20 × 10. In this case, the tooth number ratios Z1 / Z2 are 1.5, 1.7, 1.8, 1.9, and 2.0, respectively.

一方、今日では、差動装置周辺でのレイアウト上の制約を伴う伝動装置も増えており、差動装置のギヤ強度を確保しつつ差動装置を出力軸の軸方向に十分幅狭化（即ち扁平化）することが市場で要求されている。しかしながら従来の既存の差動装置では、上記歯数比率の組み合わせからも明らかなように出力軸の軸方向で幅広の構造形態となっているため、上記した市場の要求を満たすことが困難な状況にある。   On the other hand, today, the number of power transmission devices accompanied by layout restrictions around the differential device is increasing, and the differential device is sufficiently narrowed in the axial direction of the output shaft while securing the gear strength of the differential device (ie, Flattening) is required in the market. However, the conventional existing differential has a structure that is wide in the axial direction of the output shaft, as is clear from the combination of the above-mentioned tooth number ratios. It is in.

そこで差動装置のギヤ強度を確保しつつ差動装置を出力軸の軸方向に十分幅狭化（即ち扁平化）し得る差動装置Ｄの構成例を、上記した実施形態とは異なる観点より、以下に具体的に特定する。尚、この構成例に係る差動装置Ｄの各構成要素の構造は、図１〜図８（特に図１〜図５）で説明した上記実施形態の差動装置Ｄの各構成要素と同様であるので、各構成要素の参照符号は、上記実施形態のそれと同じ符号を使用し、構造説明は省略する。   Therefore, a configuration example of the differential device D capable of sufficiently narrowing (ie, flattening) the differential device in the axial direction of the output shaft while securing the gear strength of the differential device will be described from a viewpoint different from the above-described embodiment. , Are specified below. The structure of each component of the differential device D according to this configuration example is the same as each component of the differential device D of the above-described embodiment described with reference to FIGS. 1 to 8 (particularly FIGS. 1 to 5). Therefore, the same reference numerals as those of the above embodiment are used for the reference numerals of the respective components, and the description of the structure is omitted.

先ず、差動装置Ｄを出力軸Ａの軸方向に十分に幅狭化（即ち扁平化）するための基本的な考え方を、図９を併せて参照して説明すると、それは、
［１］ピニオンＰ即ち差動ギヤに対するサイドギヤＳ即ち出力ギヤの歯数比率Ｚ１／Ｚ２を従来既存の差動装置の歯数比率よりも増大させる。（これにより、ギヤのモジュール（従って歯厚）が減少してギヤ強度が低下する一方で、サイドギヤＳのピッチ円直径が増大してギヤ噛合部での伝達荷重が低減しギヤ強度が増大するが、全体としては後述する如くギヤ強度は低下する。）
［２］ピニオンＰのピッチ円錐距離ＰＣＤを従来既存の差動装置のピッチ円錐距離よりも増やす。（これにより、ギヤのモジュールが増加してギヤ強度が増大すると共に、サイドギヤＳのピッチ円直径が増大してギヤ噛合部での伝達荷重が低減しギヤ強度が増大するため、全体としては後述する如くギヤ強度は大幅に増大する。）
従って、上記［１］によるギヤ強度低下の量と、上記［２］によるギヤ強度増大の量とが等しくなるか、或いは上記［１］によるギヤ強度低下の量よりも、上記［２］によるギヤ強度増大の量の方が上回るように、歯数比率Ｚ１／Ｚ２及びピッチ円錐距離ＰＣＤを設定することにより、全体としてギヤ強度を従来既存の差動装置と比べて同等もしくは増大させることができる。 First, the basic concept for sufficiently narrowing (ie, flattening) the differential device D in the axial direction of the output shaft A will be described with reference to FIG.
[1] The ratio of the number of teeth Z1 / Z2 of the pinion P, that is, the side gear S, that is, the output gear to the differential gear, is made larger than that of the conventional differential. (Thus, while the gear module (and thus the tooth thickness) decreases and the gear strength decreases, the pitch circle diameter of the side gear S increases and the transmission load at the gear meshing portion decreases and the gear strength increases. As a whole, the gear strength decreases as described later.)
[2] The pitch cone distance PCD of the pinion P is increased more than the pitch cone distance of the conventional differential. (Thus, the number of gear modules increases, the gear strength increases, and the pitch circle diameter of the side gear S increases, the transmission load at the gear meshing portion decreases, and the gear strength increases. The gear strength is greatly increased like this.)
Therefore, the amount of reduction in gear strength due to [1] is equal to the amount of increase in gear strength according to [2], or the amount of reduction in gear strength according to [2] is greater than the amount of reduction in gear strength according to [1]. By setting the tooth number ratio Z1 / Z2 and the pitch cone distance PCD so that the amount of increase in strength is greater, the gear strength can be made equal to or greater than that of a conventional differential device as a whole.

次に上記［１］［２］に基づくギヤ強度の変化態様を数式により具体的に検証する。尚、検証は、以下の実施形態で説明する。先ず、サイドギヤＳの歯数Ｚ１を１４、ピニオンＰの歯数Ｚ２を１０とした時の差動装置Ｄ′を「基準差動装置」とする。また「変化率」とは、基準差動装置Ｄ′を基準（即ち100 ％）とした場合の各種変数の変化率である。
［１］について
サイドギヤＳのモジュールをＭ、ピッチ円直径をＰＤ₁ 、ピッチ角をθ₁ 、ピッチ円錐距離をＰＣＤ、ギヤ噛合部での伝達荷重をＦ、伝達トルクをＴとした場合に、ベベルギヤの一般的な公式より、
Ｍ＝ＰＤ₁ ／Ｚ１
ＰＤ₁ ＝２ＰＣＤ・ sinθ₁
θ₁ ＝ tan^-1（Ｚ１／Ｚ２）
これら式から、ギヤのモジュールは、
Ｍ＝２ＰＣＤ・ sin｛ tan^-1（Ｚ１／Ｚ２）｝／Ｚ１ ・・・（１）
となり、
また基準差動装置Ｄ′のモジュールは、２ＰＣＤ・ sin｛ tan^-1（７／５）｝／１４
となる。 Next, the manner in which the gear strength changes based on the above [1] and [2] will be specifically verified by mathematical expressions. The verification will be described in the following embodiment. First, the differential D 'when the number of teeth Z1 of the side gear S is 14 and the number of teeth Z2 of the pinion P is 10 is referred to as a "reference differential". The "change rate" is a change rate of various variables when the reference differential device D 'is used as a reference (that is, 100%).
[1] When the module of the side gear S is M, the pitch circle diameter is PD ₁ , the pitch angle is θ ₁ , the pitch cone distance is PCD, the transmission load at the gear meshing portion is F, and the transmission torque is T, the bevel gear From the general formula of
M = PD ₁ / Z1
PD ₁ = 2PCD · sin θ ₁
θ ₁ = tan ^-1 (Z1 / Z2)
From these equations, the gear module is
M = 2PCD · sin {tan ^-1 (Z1 / Z2)} / Z1 (1)
Becomes
The module of the reference differential device D 'is 2PCD · sin {tan ^-1 (7/5)} / 14
Becomes

従って、この両式の右項を除算することにより、基準差動装置Ｄ′に対するモジュール変化率は、次の（２）式のようになる。   Therefore, by dividing the right term in both equations, the module change rate with respect to the reference differential D 'is as shown in the following equation (2).

また、ギヤ強度（即ち歯部の曲げ強度）に相当する歯部の断面係数は、歯厚の二乗に比例する関係にあり、一方、その歯厚は、モジュールＭと略リニアな関係にある。従って、モジュール変化率の二乗は、歯部の断面係数変化率、延いてはギヤ強度の変化率に相当する。即ち、そのギヤ強度変化率は、（２）式に基づいて次の（３）式のように表される。（３）式は、ピニオンＰの歯数Ｚ２が１０の時には図１０のＬ１で示され、これにより、歯数比率Ｚ１／Ｚ２が増えるにつれてモジュール減少によりギヤ強度が低下することが判る。   Further, the section modulus of the tooth portion corresponding to the gear strength (that is, the bending strength of the tooth portion) has a relationship proportional to the square of the tooth thickness, and the tooth thickness has a substantially linear relationship with the module M. Therefore, the square of the module change rate corresponds to the change rate of the section modulus of the tooth portion, and hence the change rate of the gear strength. That is, the gear strength change rate is expressed by the following equation (3) based on the equation (2). Equation (3) is indicated by L1 in FIG. 10 when the number of teeth Z2 of the pinion P is 10, which indicates that the gear strength decreases due to a decrease in the module as the number of teeth ratio Z1 / Z2 increases.

ところで上記したベベルギヤの一般的な公式より、サイドギヤＳのトルク伝達距離は、次の（４）式のようになる。   By the way, according to the general formula of the bevel gear described above, the torque transmission distance of the side gear S is expressed by the following equation (4).

ＰＤ₁ ／２＝ＰＣＤ・ sin｛ tan^-1（Ｚ１／Ｚ２）｝・・・（４）
そして、トルク伝達距離ＰＤ₁ ／２による伝達荷重Ｆは、Ｆ＝２Ｔ／ＰＤ₁ である。従って、基準差動装置Ｄ′のサイドギヤＳにおいて、トルクＴを一定とすれば、伝達荷重Ｆとピッチ円直径ＰＤ₁ とが反比例の関係となる。また伝達荷重Ｆの変化率は、ギヤ強度の変化率とも反比例の関係にあることから、ギヤ強度の変化率は、ピッチ円直径ＰＤ₁ の変化率と等しくなる。 _{PD 1/2 = PCD · sin} {tan -1 (Z1 / Z2)} ··· (4)
Then, the transmission load F based on the torque transmission distance PD _1/2 is F = 2T / PD ₁ . Thus, the side gears S standard differential D ', if constant torque T, and the transmitted load F and pitch circle diameter PD ₁ is the inverse relationship. The rate of change in transmitted load F, since the both the rate of change of the gear strength is inversely proportional to the rate of change in gear strength is equal to the rate of change of the pitch diameter PD _1.

その結果、ピッチ円直径ＰＤ₁ の変化率は、（４）の式を用いて、次の（５）式のようになる。 As a result, the change rate of the pitch circle diameter PD _1, using the equation becomes: (5) formula (4).

（５）式は、ピニオンＰの歯数Ｚ２が１０の時には図１０のＬ２で示され、これにより、歯数比率Ｚ１／Ｚ２が増えるにつれて伝達荷重低減によりギヤ強度が高まることが判る。   Equation (5) is represented by L2 in FIG. 10 when the number of teeth Z2 of the pinion P is 10, and it can be seen that the gear strength increases as the transmission ratio decreases as the number of teeth Z1 / Z2 increases.

結局のところ、歯数比率Ｚ１／Ｚ２が増えることに伴うギヤ強度の変化率は、モジュールＭの減少によるギヤ強度の減少変化率（上記した（３）式の右項）と、伝達荷重低減によるギヤ強度の増加変化率（上記した（５）式の右項）との掛け合わせにより、次の（６）式として表される。   After all, the change rate of the gear strength with the increase in the number of teeth ratio Z1 / Z2 is the change rate of the gear strength due to the decrease of the module M (the right term of the above-mentioned formula (3)) and the reduction rate of the transmission load. By multiplying with the increase change rate of the gear strength (the right term of the above-mentioned equation (5)), it is expressed as the following equation (6).

（６）式は、ピニオンＰの歯数Ｚ２が１０の時には図１０のＬ３で示され、これにより、歯数比率Ｚ１／Ｚ２が増えるにつれて全体としてギヤ強度が低下することが判る。
［２］について
ピニオンＰのピッチ円錐距離ＰＣＤを基準差動装置Ｄ′のピッチ円錐距離よりも増やすと、変更前のＰＣＤをＰＣＤ１、変更後のＰＣＤをＰＣＤ２とした場合には、ＰＣＤの変更前後のモジュール変化率は、上記したベベルギヤの一般的な公式より、歯数を一定とすれば、（ＰＣＤ２／ＰＣＤ１）となる。 Equation (6) is represented by L3 in FIG. 10 when the number of teeth Z2 of the pinion P is 10, which indicates that the gear strength decreases as the number of teeth ratio Z1 / Z2 increases.
[2] When the pitch cone distance PCD of the pinion P is increased beyond the pitch cone distance of the reference differential device D ′, if the PCD before the change is PCD1 and the PCD after the change is PCD2, before and after the change of the PCD Is given by (PCD2 / PCD1) from the general formula of the bevel gear described above, when the number of teeth is fixed.

一方、サイドギヤＳのギヤ強度の変化率は、（３）式を導いた過程からも明らかなように、モジュール変化率の二乗に相当するため、結局のところ、
モジュール増大によるギヤ強度変化率＝（ＰＣＤ２／ＰＣＤ１）² ・・・（７）
（７）式は、図１１のＬ４で示され、これにより、ピッチ円錐距離ＰＣＤが増えるにつれてモジュール増加によりギヤ強度が増加することが判る。 On the other hand, the change rate of the gear strength of the side gear S is equivalent to the square of the module change rate, as is clear from the process of deriving the equation (3).
Gear strength change rate due to module increase = (PCD2 / PCD1) ² (7)
Equation (7) is indicated by L4 in FIG. 11, and it can be seen from this that the gear strength increases as the pitch cone distance PCD increases as the number of modules increases.

また、ピッチ円錐距離ＰＣＤを基準差動装置Ｄ′のピッチ円錐距離ＰＣＤ１よりも増やした場合に、伝達荷重Ｆが低減されるが、これによる、ギヤ強度の変化率は、前述のようにピッチ円直径ＰＤ₁ の変化率と等しくなる。またサイドギヤＳのピッチ円直径ＰＤ₁ とピッチ円錐距離ＰＣＤとは比例関係にある。従って、
伝達荷重低減によるギヤ強度変化率＝ＰＣＤ２／ＰＣＤ１ ・・・（８）
（８）式は、図１１のＬ５で示され、これにより、ピッチ円錐距離ＰＣＤが増えるにつれて伝達荷重低減によりギヤ強度が高まることが判る。 When the pitch cone distance PCD is increased beyond the pitch cone distance PCD1 of the reference differential D ', the transmission load F is reduced. As a result, the change rate of the gear strength is reduced by the pitch circle as described above. equal to the rate of change of the diameter PD _1. Also there is a proportional relationship with the pitch diameter PD ₁ and a pitch cone distance PCD side gear S. Therefore,
Gear strength change rate due to transmission load reduction = PCD2 / PCD1 (8)
Equation (8) is indicated by L5 in FIG. 11, and it can be seen from this that the gear strength increases as the pitch cone distance PCD increases as the transmission load decreases.

そして、ピッチ円錐距離ＰＣＤが増えることに伴うギヤ強度の変化率は、モジュールＭの増大によるギヤ強度の増加変化率（上記した（７）式の右項）と、ピッチ円直径ＰＤの増加に伴う伝達荷重低減によるギヤ強度の増加変化率（上記した（８）式の右項）との掛け合わせにより、次の（９）式として表される。   The rate of change in gear strength as the pitch cone distance PCD increases increases the rate of change in gear strength due to the increase in the module M (the right term in the above equation (7)) and the rate of increase in the pitch circle diameter PD. By multiplying the change rate of the gear strength by the transmission load reduction (the right term of the above-mentioned equation (8)), it is expressed as the following equation (9).

ピッチ円錐距離増大によるギヤ強度変化率＝（ＰＣＤ２／ＰＣＤ１）³ ・・（９）
（９）式は、図１１のＬ６で示され、これにより、ピッチ円錐距離ＰＣＤが増えるにつれてギヤ強度が大幅に高められることが判る。 Gear strength change rate due to increase in pitch cone distance = (PCD2 / PCD1) ³ ··· (9)
Equation (9) is indicated by L6 in FIG. 11, and it can be seen that the gear strength is greatly increased as the pitch cone distance PCD increases.

そして、［１］の手法（歯数比率増大）によるギヤ強度の低下分を、［２］の手法（ピッチ円錐距離増大）によるギヤ強度の増大分で十分補うようにして全体として差動装置のギヤ強度を従来既存の差動装置のギヤ強度と同等もしくはそれ以上とするように、歯数比率Ｚ１／Ｚ２及びピッチ円錐距離ＰＣＤの組み合わせを決定する。   Then, the decrease in gear strength due to the method [1] (increase in the number of teeth) is sufficiently compensated for by the increase in gear strength according to the method [2] (increase in pitch cone distance), so that the differential device as a whole is improved. The combination of the tooth ratio Z1 / Z2 and the pitch cone distance PCD is determined so that the gear strength is equal to or higher than the gear strength of the conventional differential.

例えば、基準差動装置Ｄ′のサイドギヤＳのギヤ強度を１００％維持する場合には、［１］で求めた歯数比率増大に伴うギヤ強度の変化率（上記した（６）式の右項）と、［２］で求めたピッチ円錐距離増大によるギヤ強度変化率（上記した（９）の右項）とを掛け合わせたものが１００％となるように設定すればよい。これより、基準差動装置Ｄ′のギヤ強度を１００％維持する場合における歯数比率Ｚ１／Ｚ２とピッチ円錐距離ＰＣＤの変化率との関係は、次の（１０）式で求められる。（１０）式は、ピニオンＰの歯数Ｚ２が１０の時には図１２のＬ７で示される。   For example, when maintaining the gear strength of the side gear S of the reference differential device D 'at 100%, the change rate of the gear strength accompanying the increase in the number of teeth determined in [1] (the right term of the above equation (6)) ) Is multiplied by the gear strength change rate due to the increase in the pitch cone distance obtained in [2] (the above-mentioned right item of (9)). Thus, the relationship between the ratio of the number of teeth Z1 / Z2 and the rate of change of the pitch cone distance PCD when the gear strength of the reference differential device D 'is maintained at 100% is obtained by the following equation (10). Equation (10) is represented by L7 in FIG. 12 when the number of teeth Z2 of the pinion P is 10.

このように（１０）式は、歯数比率Ｚ１／Ｚ２＝１４／１０とした基準差動装置Ｄ′のギヤ強度を１００％維持する場合における歯数比率Ｚ１／Ｚ２とピッチ円錐距離ＰＣＤの変化率との関係（図１２参照）を示すものであるが、図１２の縦軸のピッチ円錐距離ＰＣＤの変化率は、ピニオンＰを支持するピニオンシャフトＰＳ（即ちピニオン支持部）のシャフト径をｄ２とした場合にはｄ２／ＰＣＤの比率に変換可能である。   As described above, the equation (10) shows the change in the tooth number ratio Z1 / Z2 and the pitch cone distance PCD when maintaining the gear strength of the reference differential device D 'with the tooth number ratio Z1 / Z2 = 14/10 at 100%. FIG. 12 shows the relationship between the diameter and the ratio of the pitch cone distance PCD on the vertical axis of FIG. Can be converted to a ratio of d2 / PCD.

すなわち、従来既存の差動装置において、ピッチ円錐距離ＰＣＤの増大変化は、上記表１のようにｄ２の増大変化と相関があり、且つｄ２を一定としたときはｄ２／ＰＣＤの比率の低下として表現可能である。しかも、従来既存の差動装置においては、上記表１のように、基準差動装置Ｄ′の時にはｄ２／ＰＣＤが40〜45％の範囲に収まっている関係と、ＰＣＤを増やすとギヤ強度が増大することとから、基準差動装置Ｄ′の時には少なくともｄ２／ＰＣＤが45％以下となるように、ピニオンシャフトＰＳのシャフト径ｄ２及びピッチ円錐距離ＰＣＤを決めれば、ギヤ強度を従来既存の差動装置のギヤ強度と同等もしくはそれ以上とすることができる。つまり、基準差動装置Ｄ′の場合には、
ｄ２／ＰＣＤ≦0.45を満たせばよい。この場合、基準差動装置Ｄ′のピッチ円錐距離ＰＣＤ１に対して、増減変更後のＰＣＤをＰＣＤ２とすれば、
ｄ２／ＰＣＤ２≦0.45／（ＰＣＤ２／ＰＣＤ１）・・・（１１）
を満たせばよいということになる。そして、（１１）式を、上記した（１０）式に適用すれば、ｄ２／ＰＣＤと、歯数比率Ｚ１／Ｚ２との関係が、次の（１２）式のように変換可能である。 That is, in the conventional existing differential device, the increase change of the pitch cone distance PCD is correlated with the increase change of d2 as shown in Table 1 above, and when d2 is fixed, the ratio of d2 / PCD decreases. It is expressible. Moreover, in the conventional differential device, as shown in Table 1 above, d2 / PCD is in the range of 40 to 45% in the case of the reference differential device D ', and the gear strength is increased by increasing the PCD. Therefore, if the shaft diameter d2 of the pinion shaft PS and the pitch cone distance PCD are determined so that at least d2 / PCD is 45% or less in the case of the reference differential device D ', the gear strength can be reduced by the conventional difference. It can be equal to or higher than the gear strength of the moving device. That is, in the case of the reference differential device D ',
It is sufficient that d2 / PCD ≦ 0.45 is satisfied. In this case, if the PCD after the increase / decrease is changed to PCD2 with respect to the pitch cone distance PCD1 of the reference differential device D ′,
d2 / PCD2 ≦ 0.45 / (PCD2 / PCD1) (11)
It suffices to satisfy If the equation (11) is applied to the above-described equation (10), the relationship between d2 / PCD and the tooth number ratio Z1 / Z2 can be converted as in the following equation (12).

（１２）式の等号が成立する時において、ピニオンＰの歯数Ｚ２が１０の時には図１３のＬ８のように表すことができる。（１２）式の等号が成立する時が、基準差動装置Ｄ′のギヤ強度を１００％維持する場合のｄ２／ＰＣＤと歯数比率Ｚ１／Ｚ２との関係である。   When the number of teeth Z2 of the pinion P is 10 when the equal sign of the equation (12) is satisfied, it can be expressed as L8 in FIG. The time when the equality of the equation (12) is satisfied is the relationship between d2 / PCD and the gear ratio Z1 / Z2 when the gear strength of the reference differential D 'is maintained at 100%.

ところで従来既存の差動装置では、上述したように、通常、基準差動装置Ｄ′のような歯数比率Ｚ１／Ｚ２を１．４とするものだけでなく、歯数比率Ｚ１／Ｚ２を１．６とするものや、歯数比率Ｚ１／Ｚ２を１．４４とするものも採用されている。この事実を踏まえて、基準差動装置Ｄ′（Ｚ１／Ｚ２＝１．４）で必要十分な、即ち１００％のギヤ強度が得られると想定した場合には、従来既存の差動装置において歯数比率Ｚ１／Ｚ２が１６／１０の差動装置では、図１０から明らかなようにギヤ強度が基準差動装置Ｄ′に比べ８７％に低下していることが判る。しかしながら、この程度に低下したギヤ強度は、従来既存の差動装置では実用強度として許容され、実用されている。そこで、軸方向に扁平な差動装置においても、基準差動装置Ｄ′に対し少なくとも８７％のギヤ強度があれば、ギヤ強度が十分に確保、許容されると考えられる。   By the way, in the conventional existing differential device, as described above, the tooth number ratio Z1 / Z2 is usually not only 1.4 like the reference differential device D ', but also the tooth number ratio Z1 / Z2 is 1 as described above. .6, and a tooth number ratio Z1 / Z2 of 1.44. Based on this fact, if it is assumed that the reference differential D ′ (Z1 / Z2 = 1.4) can provide a necessary and sufficient gear strength, that is, 100% of the gear strength, the conventional differential can be used in the conventional differential. As can be seen from FIG. 10, in the differential having the number ratio Z1 / Z2 of 16/10, the gear strength is reduced to 87% as compared with the reference differential D '. However, the gear strength reduced to this extent is conventionally accepted as a practical strength in the existing differential, and is practically used. Therefore, it is considered that even in a differential device that is flat in the axial direction, if the gear strength is at least 87% of that of the reference differential device D ', the gear strength is sufficiently secured and allowed.

このような観点から、基準差動装置Ｄ′のギヤ強度を８７％維持する場合における歯数比率Ｚ１／Ｚ２と、ピッチ円錐距離ＰＣＤの変化率との関係を先ず求めると、その関係は、（１０）式を導く過程に倣って演算（即ち、歯数比率増大に伴うギヤ強度の変化率（上記した（６）式の右項）と、ピッチ円錐距離増大によるギヤ強度変化率（上記した（９）の右項）とを掛け合わせたものが８７％となるように演算）することにより、次の（１０′）式のように表すことができる。   From this point of view, the relationship between the tooth number ratio Z1 / Z2 and the rate of change of the pitch cone distance PCD when maintaining the gear strength of the reference differential device D 'at 87% is first obtained. Following the process of deriving the equation (10), the calculation (that is, the change rate of the gear strength with the increase in the number of teeth ratio (the right term of the above-mentioned equation (6))) and the change rate of the gear strength due to the increase of the pitch cone distance (the above ( 9) is calculated by multiplying the right term by 9) with 87% to obtain the following equation (10 ').

そして、前述の（１１）式を、上記した（１０′）式に適用すれば、基準差動装置Ｄ′のギヤ強度を８７％以上維持する場合におけるｄ２／ＰＣＤと、歯数比率Ｚ１／Ｚ２との関係が、次の（１３）式のように変換可能である。但し、計算の過程において、変数を用いて表される項を除き、有効数字を３桁で計算し、それ以外の桁は切り捨てで対応する都合上、実際には計算誤差によりほぼ等しいとなる場合でも、式の表現では等号で表すこととする。   Applying the above equation (11) to the above equation (10 '), d2 / PCD when the gear strength of the reference differential device D' is maintained at 87% or more, and the tooth number ratio Z1 / Z2 Can be converted as in the following equation (13). However, in the calculation process, except for terms expressed using variables, significant figures are calculated in three digits, and the remaining digits are rounded down. However, it is expressed by an equal sign in the expression.

（１３）式の等号が成立する場合において、ピニオンＰの歯数Ｚ２が１０の時には図１３のように（より具体的には、図１３のＬ９ラインのように）表すことができ、この場合に（１３）式に対応する領域は、図１３でＬ９ライン上及びＬ９ラインよりも下側の領域となる。そして、（１３）式を満たし、且つ図１３でＬ１０ラインよりも右側となる歯数比率Ｚ１／Ｚ２が２．０を超えることを満たす特定領域（図１３のハッチング領域）が、特にピニオンＰの歯数Ｚ２が１０で歯数比率Ｚ１／Ｚ２が２．０を超える軸方向に扁平な差動装置において、基準差動装置Ｄ′に対し少なくとも８７％のギヤ強度を確保可能なＺ１／Ｚ２及びｄ２／ＰＣＤの設定領域である。尚、参考までに、歯数比率Ｚ１／Ｚ２を４０／１０と、ｄ２／ＰＣＤを２０．００％とそれぞれ設定した時の実施例を図１３において例示すれば、菱形点のようになり、また歯数比率Ｚ１／Ｚ２を５８／１０と、ｄ２／ＰＣＤを１６．６７％とそれぞれ設定した時の実施例を図１３において例示すれば、三角点のようになり、これらは上記の特定領域に収まっている。これらの実施例について、シミュレーションによる強度解析を行った結果、従来と同等またはそれ以上のギヤ強度（より具体的には基準差動装置Ｄ′に対して８７％のギヤ強度またはそれ以上のギヤ強度）が得られていることが確認できた。   In the case where the equality of the equation (13) is satisfied, when the number of teeth Z2 of the pinion P is 10, it can be expressed as shown in FIG. 13 (more specifically, as shown by the L9 line in FIG. 13). In this case, the region corresponding to the expression (13) is a region above the line L9 and below the line L9 in FIG. A specific area (hatched area in FIG. 13) that satisfies the expression (13) and satisfies that the tooth number ratio Z1 / Z2 on the right side of the line L10 in FIG. In an axially flat differential having a tooth count Z2 of 10 and a tooth count ratio Z1 / Z2 exceeding 2.0, Z1 / Z2 and G1 / Z2 capable of securing at least 87% gear strength with respect to the reference differential D '; d2 / PCD setting area. For reference, FIG. 13 shows an example in which the tooth number ratio Z1 / Z2 is set to 40/10 and d2 / PCD is set to 20.00%. FIG. 13 shows an example in which the tooth number ratio Z1 / Z2 is set to 58/10 and d2 / PCD is set to 16.67%. Fits. As a result of performing a simulation-based strength analysis on these examples, a gear strength equal to or higher than the conventional one (more specifically, a gear strength of 87% or more with respect to the reference differential D ′) was obtained. ) Was obtained.

而して、上記特定領域にある扁平な差動装置は、従来既存の非扁平な差動装置と同程度のギヤ強度（例えば静ねじり荷重強度）や最大トルク伝達量を確保しながら、全体として出力軸の軸方向で十分に幅狭化な差動装置として構成されるものであり、そのため、差動装置周辺のレイアウト上の制約が多い伝動系に対しても差動装置を、高い自由度を以て無理なく容易に組込み可能となり、またその伝動系を小型化する上で頗る有利となる等の効果を達成可能である。   Thus, the flat differential device in the specific region as a whole can secure the same gear strength (for example, static torsional load strength) and the maximum torque transmission amount as the conventional non-flat differential device, and as a whole, It is configured as a differential device with a sufficiently narrow width in the axial direction of the output shaft. Therefore, the differential device has a high degree of freedom even for a transmission system with many layout restrictions around the differential device. Accordingly, it is possible to easily and easily install the power transmission system, and it is possible to achieve effects such as extremely advantageous in reducing the size of the transmission system.

また、上記特定領域にある扁平な差動装置の構造が、例えば、上述した実施形態の構造（より具体的には、図１〜８で示される構造）となる場合には、上記特定領域にある扁平な差動装置は、上述した実施形態で示した構造に伴う効果も併せて達成可能である。   When the structure of the flat differential device in the specific area is, for example, the structure of the above-described embodiment (more specifically, the structure shown in FIGS. 1 to 8), A flat differential device can also achieve the effects associated with the structure shown in the above-described embodiment.

尚、前述の説明（特に図１０，１２，１３に関する説明）は、ピニオンＰの歯数Ｚ２を１０とした時の差動装置について行っているが、本発明は、これに限定されるものではない。例えば、ピニオンＰの歯数Ｚ２を６，１２，２０とした場合にも、上記効果を達成可能な扁平な差動装置は、図１４，１５，１６のハッチングで示されるように、（１３）式で表すことができる。即ち、前述のようにして導出された（１３）式は、ピニオンＰの歯数Ｚ２の変化に関わらず適用できるものであって、例えばピニオンＰの歯数Ｚ２を６，１２，２０とした場合でも、ピニオンＰの歯数Ｚ２を１０とした場合と同様、（１３）式を満たすようにサイドギヤＳの歯数Ｚ１、ピニオンＰの歯数Ｚ２、ピニオンシャフトＰＳのシャフト径ｄ２及びピッチ円錐距離ＰＣＤを設定すれば上記効果が得られる。   Although the above description (especially the description relating to FIGS. 10, 12, and 13) has been made with respect to the differential device when the number of teeth Z2 of the pinion P is 10, the present invention is not limited to this. Absent. For example, when the number of teeth Z2 of the pinion P is set to 6, 12, and 20, the flat differential device capable of achieving the above-described effect can be obtained as shown by hatching in FIGS. It can be represented by an equation. That is, the equation (13) derived as described above can be applied regardless of a change in the number of teeth Z2 of the pinion P. For example, when the number of teeth Z2 of the pinion P is 6, 12, 20 However, similarly to the case where the number of teeth Z2 of the pinion P is set to 10, the number of teeth Z1 of the side gear S, the number of teeth Z2 of the pinion P, the shaft diameter d2 of the pinion shaft PS, and the pitch cone distance PCD so as to satisfy Expression (13). Is set, the above effect can be obtained.

また、参考までに、ピニオンＰの歯数Ｚ２を１２とした場合において、歯数比率Ｚ１／Ｚ２を４８／１２と、ｄ２／ＰＣＤを２０．００％とそれぞれ設定した時の実施例を図１５に菱形点で、歯数比率Ｚ１／Ｚ２を７０／１２と、ｄ２／ＰＣＤを１６．６７％とそれぞれ設定した時の実施例を図１５に三角点で例示する。これらの実施例について、シミュレーションによる強度解析を行った結果、従来と同等またはそれ以上のギヤ強度（より具体的には基準差動装置Ｄ′に対して８７％のギヤ強度またはそれ以上のギヤ強度）が得られていることが確認できた。また、これらの実施例は、図１５に示されるように上記特定領域に収まっている。   For reference, FIG. 15 shows an embodiment in which the number of teeth Z2 of the pinion P is set to 12 and the ratio of the number of teeth Z1 / Z2 is set to 48/12 and d2 / PCD is set to 20.00%. FIG. 15 shows an example in which the ratio of the number of teeth Z1 / Z2 is set to 70/12 and the ratio of d2 / PCD is set to 16.67% by using diamond points. As a result of performing a simulation-based strength analysis on these examples, a gear strength equal to or higher than the conventional one (more specifically, a gear strength of 87% or more with respect to the reference differential D ′) was obtained. ) Was obtained. In addition, these embodiments fall within the specific area as shown in FIG.

比較例として、上記特定範囲に収まらない実施例、例えばピニオンＰの歯数Ｚ２を１０とした場合において、歯数比率Ｚ１／Ｚ２を５８／１０と、ｄ２／ＰＣＤを２７．５０％とそれぞれ設定した時の実施例を図１３に星形点で、ピニオンＰの歯数Ｚ２を１０とした場合において、歯数比率Ｚ１／Ｚ２を４０／１０と、ｄ２／ＰＣＤを３４．２９％とそれぞれ設定した時の実施例を図１３に丸点で、ピニオンＰの歯数Ｚ２を１２とした場合において、歯数比率Ｚ１／Ｚ２を７０／１２と、ｄ２／ＰＣＤを２７．５０％とそれぞれ設定した時の実施例を図１５の星形点で、ピニオンＰの歯数Ｚ２を１２とした場合において、歯数比率Ｚ１／Ｚ２を４８／１２と、ｄ２／ＰＣＤを３４．２９％とそれぞれ設定した時の実施例を図１５の丸点で示す。これらの実施例についてシミュレーションによる強度解析を行った結果、従来と同等またはそれ以上のギヤ強度（より具体的には基準差動装置Ｄ′に対して８７％のギヤ強度またはそれ以上のギヤ強度）が得られなかったことが確認できた。つまり、上記特定範囲に収まらない実施例では上記効果が得られないことが確認できた。   As a comparative example, in an embodiment that does not fall within the above specific range, for example, when the number of teeth Z2 of the pinion P is set to 10, the tooth number ratio Z1 / Z2 is set to 58/10 and the d2 / PCD is set to 27.50%. FIG. 13 shows an example in which the number of teeth Z2 of the pinion P is set to 10, and the ratio of the number of teeth Z1 / Z2 is set to 40/10, and the ratio of d2 / PCD is set to 34.29%. When the number of teeth Z2 of the pinion P is set to 12, the ratio of the number of teeth Z1 / Z2 is set to 70/12, and the ratio of d2 / PCD is set to 27.50%. In the example at the time, when the number of teeth Z2 of the pinion P is 12 at the star point of FIG. 15, the ratio of the number of teeth Z1 / Z2 is set to 48/12, and the ratio of d2 / PCD is set to 34.29%. An example at the time is indicated by a dot in FIG.As a result of simulation-based strength analysis of these examples, the same or higher gear strength (more specifically, 87% or higher gear strength with respect to the reference differential D ') was obtained. Could not be obtained. That is, it was confirmed that the effects described above cannot be obtained in the examples that do not fall within the specific range.

以上、本発明の実施形態を説明したが、本発明は上述した実施形態に限定されるものではなく、その要旨を逸脱しない範囲で種々の設計変更が可能である。   The embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the gist of the present invention.

例えば、上述した実施形態では、差動機構ＤＭ，ＤＭＸの両外側を各々覆う一対のカバー部Ｃ，Ｃ′は、入力部材Ｉ，ＩＸとは別体に各々形成されて入力部材Ｉ，ＩＸに溶接されるが、その一方のカバー部Ｃの結合手段としては、溶接以外の種々の結合手段、例えばネジ手段やカシメ手段も実施可能であり、また他方のカバー部Ｃ′を入力部材Ｉ，ＩＸに一体に形成してもよい。
For example, in the above-described embodiment, the pair of covers C and C ′ that cover both outer sides of the differential mechanisms DM and DMX are formed separately from the input members I and IX, respectively. Various types of connecting means other than welding, such as a screw means and a caulking means, can be used as the means for connecting one of the cover parts C, and the other cover part C 'is connected to the input members I and IX. May be integrally formed.

また上述した第１，第２実施形態では、左右少なくとも一方のカバー部Ｃ，Ｃ′の側壁部Ｃｓに肉抜き部８を設けたものを示したが、左右何れのカバー部Ｃ，Ｃ′の側壁部Ｃｓにも肉抜き部８を形成しないようにして（即ち側壁部Ｃｓを円板状に形成して）、側壁部Ｃｓにより対応するサイドギヤＳの背面全面を覆うようにしてもよい。尚、この場合には、肉抜き部８を有しないカバー部Ｃ，Ｃ′の円板状の側壁部Ｃｓを、入力部材Ｉの取付孔Ｉｈの被溶接部２１に全周に亘り突き当て溶接ｗしてもよいし、或いはその周方向の一部にだけ突き当て溶接ｗしてもよい。   In the above-described first and second embodiments, the lightening portion 8 is provided on the side wall portion Cs of at least one of the right and left cover portions C and C ′. The lightening portion 8 may not be formed on the side wall portion Cs (that is, the side wall portion Cs is formed in a disk shape), and the entire rear surface of the corresponding side gear S may be covered by the side wall portion Cs. In this case, the disc-shaped side wall portions Cs of the cover portions C and C ′ having no lightening portion 8 are butted and welded to the welded portion 21 of the mounting hole Ih of the input member I over the entire circumference. w or butt welding w only on a part of the circumferential direction.

また上述した実施形態では、入力部材Ｉ，ＩＸが、入力部としての入力歯部Ｉｇ又は被動プーリＩｐを一体に備えるものを示したが、本発明では、入力部材Ｉ，ＩＸとは別体に形成した、入力部としてのリングギヤ又は被動プーリを後付けで入力部材Ｉ，ＩＸの外周部に固定するようにしてもよい。
Further, in the above-described embodiment, the input members I and IX are integrally provided with the input tooth portion Ig or the driven pulley Ip as an input portion. However, in the present invention, the input members I and IX are provided separately from the input members I and IX. The formed ring gear or driven pulley as an input unit may be fixed to the outer peripheral portions of the input members I and IX later.

また本発明の入力部材は、上述した実施形態のような入力歯部Ｉｇや被動プーリＩｐを備えない構造であってもよく、例えば入力部材Ｉ，ＩＸが、動力伝達経路で入力部材Ｉ，ＩＸよりも上流側に位置する駆動部材（例えば遊星歯車機構や減速歯車機構の出力部材、無端伝動帯式伝動機構の被動輪等）と連動、連結されることにより、入力部材Ｉ，ＩＸに回転駆動力が入力されるようにしてもよい。この場合は、その入力部材Ｉ，ＩＸの、上記駆動部材と連動、連結される部分が、入力部材の入力部となる。   Further, the input member of the present invention may have a structure that does not include the input tooth portion Ig and the driven pulley Ip as in the above-described embodiment. For example, the input members I and IX are connected to the input members I and IX in the power transmission path. The input members I and IX are rotationally driven by being linked to and connected to driving members (for example, output members of a planetary gear mechanism or a reduction gear mechanism, driven wheels of an endless transmission band type transmission mechanism, etc.) located on the upstream side. Force may be input. In this case, portions of the input members I and IX that are linked to and connected to the driving member serve as input portions of the input members.

また、上述した第１，第２実施形態では、一対のサイドギヤＳの背面を一対のカバー部Ｃ，Ｃ′でそれぞれ覆うものを示したが、本発明では、一方のサイドギヤＳの背面にのみカバー部を設けるようにしてもよい。この場合、例えば、カバー部が設けられない側に、上記上流側に位置する駆動部材を配設して、カバー部が設けられない側で駆動部材と入力部材とを連動、連結させるようにしてもよい。   Further, in the first and second embodiments described above, the rear surfaces of the pair of side gears S are respectively covered with the pair of cover portions C and C ′. However, in the present invention, the cover is provided only on the rear surface of one side gear S. A unit may be provided. In this case, for example, the drive member located on the upstream side is disposed on the side where the cover is not provided, and the drive member and the input member are interlocked and connected on the side where the cover is not provided. Is also good.

また、上述した実施形態において、差動装置Ｄは、左右車軸の回転差を許容するものであったが、前輪と後輪の回転差を吸収するセンターデフにも本発明の差動装置を実施可能である。   Further, in the above-described embodiment, the differential device D allows the rotational difference between the left and right axles. However, the differential device of the present invention is also applied to a center differential that absorbs the rotational difference between the front wheels and the rear wheels. It is possible.

Ａ，Ａ′・・出力軸
Ｃ，Ｃ′・・カバー部
Ｃｂ・・・・ボス部
Ｃｓ・・・・側壁部
Ｄ・・・・・差動装置
ＤＣ，ＤＣＸ・・デフケース
ＤＭ，ＤＭＸ・・差動機構
ｄ２・・・・ピニオンシャフトの直径、支持軸部の直径（ピニオン支持部の直径，差動ギヤ支持部の直径）
Ｉ，ＩＸ・・・・入力部材
Ｉｇ・・・・入力歯部（入力部）
Ｉｐ・・・・被動プーリ（入力部）
Ｉｈ・・・・取付孔
Ｉｓ・・・・支持壁部
Ｐ・・・・・ピニオン（差動ギヤ）
ＰＣＤ・・・ピッチ円錐距離
ＰＳ・・・・ピニオンシャフト（ピニオン支持部，差動ギヤ支持部）
ＰＳ′・・・支持軸部（ピニオン支持部，差動ギヤ支持部）
Ｓ・・・・・サイドギヤ（出力ギヤ）
Ｓｇ・・・・歯部
ｗ・・・・・溶接
２１・・・・被溶接部
２２・・・・被圧入部
２２ｏ・・・外端
２３・・・・接続面
２３ａ・・・延出部
２３ｂ・・・傾斜部
２４・・・・空間
３１・・・・大径部
３２・・・・小径部
３３・・・・段差面 A, A 'output shaft C, C' cover part Cb boss part Cs side wall part D differential device DC, DCX, differential case DM, DMX Differential mechanism d2: diameter of pinion shaft, diameter of support shaft (diameter of pinion support, diameter of differential gear support)
I, IX ... input member Ig ... input tooth part (input part)
Ip ··· Driven pulley (input unit)
Ih: Mounting hole Is: Support wall P: Pinion (differential gear)
PCD: pitch cone distance PS: pinion shaft (pinion support, differential gear support)
PS ': Support shaft (pinion support, differential gear support)
S ... side gear (output gear)
Sg: tooth portion w: weld 21: welded portion 22: press-fitted portion 22o: outer end 23: connecting surface 23a: extending portion 23b: inclined portion 24: space 31: large diameter portion 32: small diameter portion 33: step surface

Claims (2)

デフケース（ＤＣ，ＤＣＸ）と、前記デフケース（ＤＣ，ＤＣＸ）に収納されて該デフケース（ＤＣ，ＤＣＸ）の回転力を互いに独立した一対の出力軸（Ａ，Ａ′）に分配して伝達する差動機構（ＤＭ，ＤＭＸ）とを備えた差動装置であって、
前記デフケース（ＤＣ，ＤＣＸ）は、回転力を受ける入力部（Ｉｇ，Ｉｐ）を有すると共に少なくとも軸方向の一方側の端部が開放された入力部材（Ｉ，ＩＸ）と、前記入力部材（Ｉ，ＩＸ）の前記軸方向の一方側の端部の開放部分を塞ぐ少なくとも１個のカバー部（Ｃ，Ｃ′）とを備え、
前記入力部材（Ｉ，ＩＸ）は、前記カバー部（Ｃ，Ｃ′）を前記入力部材（Ｉ，ＩＸ）の軸方向に嵌合して溶接（ｗ）させる被溶接部（２１）と、前記被溶接部（２１）よりも前記入力部材（Ｉ，ＩＸ）の半径方向内方側且つ軸方向内方側に在って前記カバー部（Ｃ，Ｃ′）を圧入させる被圧入部（２２）と、前記被溶接部（２１）及び前記被圧入部（２２）間を接続して前記カバー部（Ｃ，Ｃ′）との間に圧入の際の前記被圧入部（２２）の変形を許容する空間（２４）を形成する接続面（２３）とを有し、
前記接続面（２３）の、前記被溶接部（２１）に連なる一端部は、該被溶接部（２１）から前記半径方向外方側に延出し、前記被圧入部（２２）の一部と前記空間（２４）とは、前記入力部材（Ｉ，ＩＸ）の回転中心から放射方向に見て互いにオーバラップするように配置されることを特徴とする差動装置。 A differential case (DC, DCX) and a differential housing that is housed in the differential case (DC, DCX) and distributes and transmits the rotational force of the differential case (DC, DCX) to a pair of independent output shafts (A, A ′). A differential device having a moving mechanism (DM, DMX),
The differential case (DC, DCX) includes an input member (I, IX) having an input portion (Ig, Ip) for receiving a rotational force and having at least one end in the axial direction opened. , IX) at least one cover portion (C, C ′) for closing an open portion at one end of the axial direction.
The input member (I, IX) includes a welded portion (21) that fits the cover portion (C, C ′) in the axial direction of the input member (I, IX) to weld (w), A press-fit portion (22) which is located radially inward of the input member (I, IX) and axially inward of the input member (I, IX) relative to the welded portion (21) and press-fits the cover portion (C, C '). Between the welded portion (21) and the press-fitted portion (22) to allow deformation of the press-fitted portion (22) during press-fitting between the cover portion (C, C '). A connection surface (23) forming a space (24) that
One end of the connection surface (23) connected to the welded portion (21) extends radially outward from the welded portion (21), and is connected to a part of the press-fitted portion (22). wherein a space (24), said input member (I, IX) differential device according to claim Rukoto are arranged to overlap each other from the center of rotation as viewed in the radial direction of the. 前記カバー部（Ｃ，Ｃ′）は、前記出力軸（Ａ，Ａ′）を同心状に囲繞するボス部（Ｃｂ）と、前記ボス部（Ｃｂ）から前記半径方向外方側に張出すように連設される側壁部（Ｃｓ）とを有し、前記側壁部（Ｃｓ）の外周部には、前記被溶接部（２１）に嵌合して溶接（ｗ）される大径部（３１）と、前記大径部（３１）の軸方向内端に段差面（３３）を介して連なり且つ前記被圧入部（２２）に圧入される小径部（３２）とが形成され、前記被圧入部（２２）の軸方向外端（２２ｏ）が前記段差面（３３）に当接又は近接していると共に、前記接続面（２３）が、前記軸方向外端（２２ｏ）又はその近傍部から前記半径方向外方に向かうにつれて前記段差面（３３）から徐々に離間する傾斜部（２３ｂ）を有していることを特徴とする、請求項１に記載の差動装置。 The cover portion (C, C ') includes a boss portion (Cb) concentrically surrounding the output shaft (A, A'), and extends from the boss portion (Cb) outward in the radial direction. And a large-diameter portion (31) fitted to and welded (w) to the welded portion (21) on the outer peripheral portion of the side wall portion (Cs). ), And a small-diameter portion (32) which is connected to the inner end in the axial direction of the large-diameter portion (31) via a step surface (33) and is press-fitted into the press-fitted portion (22). The axially outer end (22o) of the portion (22) is in contact with or close to the step surface (33), and the connecting surface (23) is moved from the axially outer end (22o) or the vicinity thereof. An inclined portion (23b) that is gradually separated from the step surface (33) as going outward in the radial direction. Differential apparatus according to claim 1.

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