JP6880800B2 - Hollow camshaft - Google Patents

Hollow camshaft Download PDF

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JP6880800B2
JP6880800B2 JP2017023214A JP2017023214A JP6880800B2 JP 6880800 B2 JP6880800 B2 JP 6880800B2 JP 2017023214 A JP2017023214 A JP 2017023214A JP 2017023214 A JP2017023214 A JP 2017023214A JP 6880800 B2 JP6880800 B2 JP 6880800B2
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axial direction
hollow
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end side
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JP2018128000A (en
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祐輔 木戸
祐輔 木戸
田辺　幹雄
幹雄 田辺
吉原　昭
昭 吉原
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Mitsubishi Motors Corp
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Mitsubishi Motors Corp
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Description

この発明は、内部に中空部を有する中空カムシャフトに関するものである。 The present invention relates to a hollow camshaft having a hollow portion inside.

エンジンの動弁系を駆動するカムシャフトとして、重量軽減を目的として、その内部に軸方向一端から他端に至る中空部を有する中空カムシャフトが採用される場合がある。 As the camshaft that drives the valve train of the engine, a hollow camshaft having a hollow portion from one end to the other end in the axial direction may be adopted for the purpose of weight reduction.

この中空カムシャフトは、一般的に、中子を利用した鋳造法によって製造されている。型枠の中に砂型等からなる中子が配置され、溶湯が注入されて金属が固化した後に、中子をショットブラスト等により排除している（例えば、特許文献１参照）。 This hollow camshaft is generally manufactured by a casting method using a core. A core made of a sand mold or the like is arranged in the mold, and after the molten metal is injected to solidify the metal, the core is removed by shot blasting or the like (see, for example, Patent Document 1).

特開２００１−１０５１００号公報Japanese Unexamined Patent Publication No. 2001-105100

ところで、カムシャフトの軸方向端部には、ギヤやスプロケット、プーリ等を取り付けるための雌ネジ部が形成されている。この雌ネジ部は、軸方向いずれかの側の端部において、中空部の内面に形成され、ギヤやスプロケット、プーリ等に挿通された固定用のボルトが、ねじ込まれるようになっている。 By the way, a female screw portion for attaching a gear, a sprocket, a pulley, or the like is formed at an axial end portion of the camshaft. The female screw portion is formed on the inner surface of the hollow portion at an end portion on any side in the axial direction, and a fixing bolt inserted into a gear, a sprocket, a pulley, or the like is screwed into the female screw portion.

ここで、カムシャフトのさらなる軽量化を図るために、中空部の断面積を大きくしようとすると、それに合わせて、中空部の内面に形成される雌ネジ部のネジ径も大きくなってしまう。雌ネジ部には、回転を伝達するために大きな応力が作用するので、雌ネジ部のネジ径が大きくなると強度を確保するために、雌ネジ部周囲におけるカムシャフトの外径を大きくしなければならない。このため、中空部の断面積を大きくしても、必ずしもカムシャフトの軽量化を図ることができない。 Here, if an attempt is made to increase the cross-sectional area of the hollow portion in order to further reduce the weight of the camshaft, the screw diameter of the female screw portion formed on the inner surface of the hollow portion also increases accordingly. Since a large stress acts on the female screw part to transmit rotation, the outer diameter of the camshaft around the female screw part must be increased in order to secure the strength when the screw diameter of the female screw part becomes large. It doesn't become. Therefore, even if the cross-sectional area of the hollow portion is increased, the weight of the camshaft cannot always be reduced.

そこでこの発明の課題は、中空カムシャフトに関し、その強度を確保しつつより軽量化することである。 Therefore, an object of the present invention is to reduce the weight of the hollow camshaft while ensuring its strength.

上記の課題を解決するために、この発明は、軸方向に延びる中空部と、前記中空部の軸方向一端の内面に形成された雌ネジ部とを備え、前記中空部は、前記雌ネジ部よりも他端側に一端側から他端側に向かって断面積が拡大する断面変化部と、前記断面変化部よりも他端側全域に前記雌ネジ部よりも断面積が大きい大断面部とを備える中空カムシャフトを採用した。 In order to solve the above problems, the present invention includes a hollow portion extending in the axial direction and a female screw portion formed on the inner surface of one end of the hollow portion in the axial direction, and the hollow portion is the female screw portion. A cross-sectional change portion in which the cross-sectional area expands from one end side to the other end side on the other end side, and a large cross-sectional portion having a larger cross-sectional area than the female screw portion over the entire other end side of the cross-sectional change portion. A hollow camshaft equipped with is adopted.

ここで、前記大断面部は、軸方向他端に形成されたプラグ嵌込部と、前記断面変化部から前記プラグ嵌込部まで同一の断面で継続する断面一定部とを備える構成を採用することができる。 Here, the large cross-section portion adopts a configuration including a plug fitting portion formed at the other end in the axial direction and a constant cross-section portion that continues in the same cross section from the cross-section changing portion to the plug fitting portion. be able to.

また、前記断面変化部は、テーパ状に断面積が拡大する構成を採用することができる。 Further, the cross-sectional change portion can adopt a configuration in which the cross-sectional area is expanded in a tapered shape.

これらの各態様において、軸方向に沿って軸心から離れる方向に突出する複数の突出部が形成され、前記断面変化部は、軸方向に隣り合う前記突出部同士の対向する端面間に配置される構成を採用することができる。 In each of these embodiments, a plurality of projecting portions projecting along the axial direction away from the axial center are formed, and the cross-sectional changing portion is arranged between the opposing end faces of the projecting portions adjacent to each other in the axial direction. Configuration can be adopted.

このとき、前記突出部は、軸方向に沿って断続的に配置されたカム部、又は、軸方向に沿って断続的に配置されたジャーナル部の軸方向両側に配置されるフランジ部である構成を採用することができる。 At this time, the protruding portion is a cam portion intermittently arranged along the axial direction or a flange portion arranged on both sides in the axial direction of the journal portion intermittently arranged along the axial direction. Can be adopted.

前記突出部の端面の裾部に、半径方向内側に向かうにつれて軸方向へ湾曲してその終端部で前記突出部の側方の円筒面に接続されるアール部を備え、前記断面変化部は、軸方向に隣り合う前記アール部同士の前記終端部間に配置される構成を採用することができる。 The hem portion of the end surface of the protruding portion is provided with a rounded portion that is curved in the axial direction toward the inside in the radial direction and is connected to the cylindrical surface on the side of the protruding portion at the end portion. It is possible to adopt a configuration in which the radius portions adjacent to each other in the axial direction are arranged between the end portions.

また、前記断面変化部は前記ジャーナル部と同じ軸方向範囲にある構成を採用することができる。 Further, the cross-section changing portion may adopt a configuration in the same axial range as the journal portion.

この発明は、軸方向一端から軸方向他端に至る中空部と、中空部の軸方向一端の内面に雌ネジ部が形成された中空カムシャフトにおいて、中空部を、雌ネジ部よりも他端側に一端側から他端側に向かって断面積が拡大する断面変化部と、断面変化部よりも他端側全域に雌ネジ部よりも断面積が大きい大断面部とを有する構成としたので、中空カムシャフトの強度を確保しつつより軽量化することができる。 According to the present invention, in a hollow camshaft in which a hollow portion extending from one end in the axial direction to the other end in the axial direction and a female screw portion are formed on the inner surface of the one end in the axial direction of the hollow portion, the hollow portion is formed at the other end of the female screw portion. Since the configuration has a cross-sectional change portion in which the cross-sectional area expands from one end side to the other end side, and a large cross-sectional portion having a larger cross-sectional area than the female screw portion in the entire other end side of the cross-sectional change portion. , It is possible to reduce the weight while ensuring the strength of the hollow camshaft.

この発明の一実施形態を示す中空カムシャフトの縦断面図である。It is a vertical sectional view of the hollow camshaft which shows one Embodiment of this invention. 図１の要部拡大図である。It is an enlarged view of the main part of FIG. （ａ）（ｂ）は、同実施形態と従来例とを比較するグラフ図である。(A) and (b) are graphs comparing the same embodiment with the conventional example.

以下、この発明の実施形態を、図面に基づいて説明する。この実施形態の中空カムシャフト２０は、軸方向に延びる中空部１０を有するベース軸２１と、ベース軸２１の軸方向に沿って断続的に配置されたジャーナル部２３及びカム部２２と、軸方向一端の中空部１０の内面に形成された雌ネジ部１１とを備えている。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. The hollow camshaft 20 of this embodiment has a base shaft 21 having a hollow portion 10 extending in the axial direction, a journal portion 23 and a cam portion 22 intermittently arranged along the axial direction of the base shaft 21, and an axial direction. It is provided with a female screw portion 11 formed on the inner surface of the hollow portion 10 at one end.

中空部１０は、軸状部材であるベース軸２１の軸心と同心に形成され、軸方向一端と他端の端面に開口することでベース軸２１の軸方向全長に設けられている。 The hollow portion 10 is formed concentrically with the axial center of the base shaft 21 which is a shaft-shaped member, and is provided on the entire axial length of the base shaft 21 by opening at one end face and the other end face in the axial direction.

図１に示すように、ベース軸２１の外面には、軸方向に沿って断続的に５つのジャーナル部２３；２３ａ，２３ｂ，２３ｃ，２３ｄ，２３ｅが形成されている。このジャーナル部２３の外面には、中空カムシャフト２０をエンジンのシリンダヘッド内に回転自在に支持するための軸受に対面する円筒面が形成されている。軸受構造としては、一般的に、すべり軸受が作用される。 As shown in FIG. 1, five journal portions 23; 23a, 23b, 23c, 23d, 23e are intermittently formed on the outer surface of the base shaft 21 along the axial direction. On the outer surface of the journal portion 23, a cylindrical surface facing a bearing for rotatably supporting the hollow camshaft 20 in the cylinder head of the engine is formed. As a bearing structure, a plain bearing is generally applied.

円筒面からなるジャーナル部２３の外面に、二つ割り状態のカムベアリング４；４ａ，４ｂ，４ｃ，４ｄ，４ｅが宛がわれて各ジャーナル部２３の軸周り全周を覆い、そのカムベアリング４を介して、中空カムシャフト２０がシリンダヘッドに軸周り回転自在となる。 Cam bearings 4; 4a, 4b, 4c, 4d, 4e in a split state are addressed to the outer surface of the journal portion 23 made of a cylindrical surface to cover the entire circumference of each journal portion 23 around the axis, and the cam bearing 4 is used. The hollow camshaft 20 is rotatable around the axis of the cylinder head.

最も軸方向一端側に位置するジャーナル部２３ａの軸方向両側には、軸周り全周に亘って外径側へ突出するフランジ部２４が配置されている。それ以外のジャーナル部２３の軸方向両側には、軸周り全周に亘るカム部２２；２２ａ，２２ｂ，２２ｃ，２２ｄが配置されている。 Flange portions 24 projecting to the outer diameter side over the entire circumference around the axis are arranged on both sides of the journal portion 23a located on one end side in the axial direction in the axial direction. Cam portions 22; 22a, 22b, 22c, 22d extending all around the axis are arranged on both sides of the other journal portion 23 in the axial direction.

フランジ部２４やカム部２２は、いずれも、ベース軸２１の外面において、軸心から離れる方向に突出する突出部である。これらの突出部は軸方向に沿って断続的に配置され、その突出部の端面ｗは、カムベアリング４を軸方向に位置決めするためのスラストベアリングの機能も発揮している。 The flange portion 24 and the cam portion 22 are both protruding portions on the outer surface of the base shaft 21 that project in a direction away from the axis. These protrusions are arranged intermittently along the axial direction, and the end surface w of the protrusions also functions as a thrust bearing for positioning the cam bearing 4 in the axial direction.

カム部２２は、エンジンの気筒数に対応して、必要な数だけ配置される。この実施形態では、図１に示すように、４気筒のエンジンに対応している。 A required number of cam portions 22 are arranged according to the number of cylinders of the engine. In this embodiment, as shown in FIG. 1, it corresponds to a 4-cylinder engine.

中空カムシャフト２０の軸方向一端に、ボルト３を介してカムプーリ５が固定される。カムプーリ５にはタイミングベルトが巻回されて、クランクシャフトの回転が中空カムシャフト２０に伝達されるようになっている。クランクシャフトの回転に同期して中空カムシャフト２０が駆動され、中空カムシャフト２０によりロッカアーム等を介して、吸気側、排気側のバルブが開閉駆動され、エンジンの運転が行われる。 A cam pulley 5 is fixed to one end of the hollow camshaft 20 in the axial direction via a bolt 3. A timing belt is wound around the cam pulley 5 so that the rotation of the crankshaft is transmitted to the hollow camshaft 20. The hollow camshaft 20 is driven in synchronization with the rotation of the crankshaft, and the valves on the intake side and the exhaust side are opened and closed by the hollow camshaft 20 via the rocker arm and the like to operate the engine.

なお、吸気側と排気側の両方のバルブを１本の中空カムシャフト２０で動作させる場合もあるし、吸気側と排気側の両方のバルブを複数本の中空カムシャフト２０で別々に動作させる場合もある。 In some cases, both the intake side and exhaust side valves are operated by one hollow camshaft 20, and in some cases, both the intake side and exhaust side valves are operated separately by a plurality of hollow camshafts 20. There is also.

中空部１０の軸方向一端の内面には、カムプーリ５を固定するボルト３の雄ネジ部３ａがねじ込まれる雌ネジ部１１が形成されている。 A female screw portion 11 into which the male screw portion 3a of the bolt 3 for fixing the cam pulley 5 is screwed is formed on the inner surface of one end in the axial direction of the hollow portion 10.

また、中空部１０は、雌ネジ部１１の軸方向他端側に隣接して円筒状の内面を有する接続部１２、さらに軸方向他端側には、一端側から他端側に向かって断面積が拡大する断面変化部１３、さらに、断面変化部１３よりも他端側全域には、雌ネジ部１１よりも断面積が大きい大断面部１６を備えている。 Further, the hollow portion 10 is a connecting portion 12 having a cylindrical inner surface adjacent to the other end side in the axial direction of the female screw portion 11, and further cut off from one end side to the other end side on the other end side in the axial direction. A cross-sectional change portion 13 whose area is expanded, and a large cross-sectional portion 16 having a larger cross-sectional area than the female screw portion 11 are provided over the entire other end side of the cross-sectional change portion 13.

接続部１２は断面円形であり、中空部１０の内面に雌ネジ部１１を形成する前までは、軸方向一端まで連続した状態である。軸方向一端からタップで雌ネジ部１１を形成した際に、ねじ溝が形成されることなく円筒状の内面として残った部分が、図２の接続部１２である。 The connecting portion 12 has a circular cross section, and is in a continuous state up to one end in the axial direction until the female screw portion 11 is formed on the inner surface of the hollow portion 10. When the female screw portion 11 is formed by tapping from one end in the axial direction, the portion remaining as a cylindrical inner surface without forming a thread groove is the connection portion 12 in FIG.

大断面部１６は、軸方向他端に形成されたプラグ嵌込部１５と、断面変化部１３からプラグ嵌込部１５まで同一の断面で継続する断面一定部１４とを備えている。 The large cross-section portion 16 includes a plug fitting portion 15 formed at the other end in the axial direction, and a cross-section constant portion 14 that continues from the cross-section changing portion 13 to the plug fitting portion 15 in the same cross section.

プラグ嵌込部１５には、潤滑油路である中空部１０を密封するため、プラグが差し込まれるようになっている。プラグ嵌込部１５は、通常は、断面一定部１４よりも大断面に形成されるが、エンジンの仕様によっては、断面一定部１４より小断面である場合も考えられる。ただし、プラグ嵌込部１５は、雌ネジ部１１の最大径部分の内径、すなわち、雌ネジ部１１のネジ山とネジ山との間の谷の底の部分とベース軸２１の軸心からの距離（半径）を２倍した数値よりも、相対的に大きい内径（直径）を有する。これにより、プラグ嵌込部１５は、雌ネジ部１１よりも相対的に断面積が大きいものである。 A plug is inserted into the plug fitting portion 15 in order to seal the hollow portion 10 which is a lubricating oil passage. The plug fitting portion 15 is usually formed to have a larger cross section than the constant cross section 14, but depending on the specifications of the engine, the plug fitting portion 15 may have a smaller cross section than the constant cross section 14. However, the plug fitting portion 15 is formed from the inner diameter of the maximum diameter portion of the female thread portion 11, that is, the bottom portion of the valley between the threads of the female thread portion 11 and the axis of the base shaft 21. It has an inner diameter (diameter) that is relatively larger than the value obtained by doubling the distance (radius). As a result, the plug fitting portion 15 has a relatively larger cross-sectional area than the female screw portion 11.

断面一定部１４は断面円形であり、全長に亘って同一の断面で継続する。断面一定部１４の内径（直径）は、同じく、雌ネジ部１１の最大径部分の内径、すなわち、雌ネジ部１１のネジ山とネジ山との間の谷の底の部分とベース軸２１の軸心からの距離（半径）を２倍した数値よりも、相対的に大きい内径（直径）を有する。これにより、断面一定部１４は、雌ネジ部１１よりも相対的に断面積が大きいものである。 The constant cross-section portion 14 has a circular cross-section and continues with the same cross-section over the entire length. Similarly, the inner diameter (diameter) of the constant cross-section portion 14 is the inner diameter of the maximum diameter portion of the female thread portion 11, that is, the bottom portion of the valley between the threads of the female thread portion 11 and the base shaft 21. It has an inner diameter (diameter) that is relatively larger than the value obtained by doubling the distance (radius) from the axis. As a result, the constant cross-sectional area 14 has a relatively larger cross-sectional area than the female threaded portion 11.

断面変化部１３は、軸方向一端側から軸方向他端側に向かって、テーパ状に断面積が拡大する。そのテーパの母線の軸方向に対する角度αは、応力集中を抑制する観点からより緩やかであることが好ましいが、特に、テーパの軸方向に対する角度αは、４５°以下とすることが望ましい。 The cross-sectional area of the cross-sectional change portion 13 expands in a tapered shape from one end side in the axial direction to the other end side in the axial direction. The angle α of the taper bus with respect to the axial direction is preferably gentler from the viewpoint of suppressing stress concentration, and in particular, the angle α of the taper with respect to the axial direction is preferably 45 ° or less.

このように、中空部１０を、雌ネジ部１１よりも他端側において、一端側から他端側に向かって断面積が拡大する断面変化部１３と、断面変化部１３よりも他端側全域に雌ネジ部１１よりも断面積が大きい大断面部１６とを有する構成としたので、雌ネジ部１１の径を拡大することなく、中空部１０全体の総容積を増大させ、中空カムシャフト２０の軽量化を実現できる。すなわち、カムプーリ５を固定するボルト３の径を増大させることがないので、雌ネジ部１１付近における中空カムシャフト２０の肉厚を増やす必要がなく、その結果、中空カムシャフト２０の強度を確保しつつより軽量化することが可能である。 In this way, on the other end side of the female screw portion 11, the hollow portion 10 has a cross-sectional change portion 13 in which the cross-sectional area expands from one end side to the other end side, and the entire other end side of the cross-section change portion 13. Since the structure has a large cross-sectional portion 16 having a cross-sectional area larger than that of the female screw portion 11, the total volume of the entire hollow portion 10 can be increased without increasing the diameter of the female screw portion 11, and the hollow camshaft 20 can be used. Can be made lighter. That is, since the diameter of the bolt 3 for fixing the cam pulley 5 is not increased, it is not necessary to increase the wall thickness of the hollow camshaft 20 in the vicinity of the female screw portion 11, and as a result, the strength of the hollow camshaft 20 is secured. However, it is possible to reduce the weight.

また、断面変化部１３は、軸方向に隣り合う突出部同士の対向する端面ｗ，ｗ間に配置される。 Further, the cross-section changing portion 13 is arranged between the end faces w and w of the protruding portions adjacent to each other in the axial direction.

この実施形態では、図２に示すように、断面変化部１３は、軸方向に隣り合うフランジ部２４の端面ｗと、カム部２２の端面ｗとの間に配置されている。すなわち、断面変化部１３は、外径側への突出部であるフランジ部２４やカム部２２が介在する軸方向範囲には、重複して配置されないようになっている。これにより、応力が集中しやすい突出部付近におけるベース軸２１の断面の変化を抑制し、その強度を高めている。 In this embodiment, as shown in FIG. 2, the cross-section changing portion 13 is arranged between the end surface w of the flange portions 24 adjacent to each other in the axial direction and the end surface w of the cam portion 22. That is, the cross-section changing portion 13 is not arranged so as to overlap in the axial range in which the flange portion 24 and the cam portion 22, which are protruding portions toward the outer diameter side, are interposed. As a result, changes in the cross section of the base shaft 21 in the vicinity of the protruding portion where stress is likely to be concentrated are suppressed, and the strength thereof is increased.

断面変化部１３の一端（始端と称する）と他端（終端と称する）は、軸方向へ隣り合う突出部の対向する端面ｗ，ｗよりも軸方向内側に配置されていることが望ましく、断面変化部１３の範囲は、例えば、図２に符号Ｌ１で示す範囲よりも内側であることが望ましい。 It is desirable that one end (referred to as the start end) and the other end (referred to as the end) of the cross-section changing portion 13 are arranged axially inside the opposite end faces w and w of the projecting portions adjacent in the axial direction. For example, it is desirable that the range of the changing portion 13 is inside the range indicated by reference numeral L1 in FIG.

さらには、断面変化部１３は、軸方向に隣り合う突出部の裾部に設けられるアール部Ｒの終端部間に配置されることが望ましい。 Further, it is desirable that the cross-section changing portion 13 is arranged between the end portions of the rounded portions R provided at the hem portions of the projecting portions adjacent to each other in the axial direction.

アール部Ｒは、図２に示すように、突出部の端面ｗの裾部において、半径方向内側に向かうにつれて軸方向外側へ湾曲して、その終端部で、突出部の側方の円筒面に接続される形状となっている。すなわち、アール部Ｒと円筒面との接続部がアール部Ｒの終端部であり、断面変化部１３は、軸方向に隣り合うアール部Ｒの終端部間、例えば、図２に符号Ｌ２で示す範囲よりも内側に配置される。このように、断面変化部１３を、フランジ部２４やカム部２２等の突出部の端面ｗ，ｗ間、及び、その突出部の裾部のアール部Ｒが介在する軸方向範囲に重複して配置されないようにすれば、さらなる強度の確保が可能である。 As shown in FIG. 2, the rounded portion R is curved outward in the axial direction as it goes inward in the radial direction at the hem of the end surface w of the protruding portion, and at the end portion thereof, it becomes a cylindrical surface on the side of the protruding portion. It has a shape to be connected. That is, the connecting portion between the rounded portion R and the cylindrical surface is the terminal portion of the rounded portion R, and the cross-sectional change portion 13 is indicated by reference numeral L2 between the terminal portions of the rounded portions R adjacent to each other in the axial direction, for example, FIG. Placed inside the range. In this way, the cross-section changing portion 13 overlaps the axial range in which the end faces w and w of the protruding portions such as the flange portion 24 and the cam portion 22 and the rounded portion R at the hem of the protruding portion are interposed. If it is not arranged, further strength can be secured.

なお、断面変化部１３の始端とその始端側の端面ｗとの距離、及び、断面変化部１３の終端とその終端側の端面ｗとの距離は、できるだけ長いことが望ましいが、断面変化部１３のテーパの軸方向に対する角度αは、前述のように、４５°以下に抑えることが望ましい。 It is desirable that the distance between the start end of the cross-section change portion 13 and the end face w on the start end side and the distance between the end of the cross-section change portion 13 and the end face w on the end side thereof are as long as possible, but the cross-section change portion 13 It is desirable that the angle α of the taper with respect to the axial direction be suppressed to 45 ° or less as described above.

また、断面変化部１３の軸方向範囲は、軸方向へ隣り合う突出部の対向する端面ｗ，ｗ間の中点を含むことが望ましく、さらには、断面変化部１３の始端とその始端側の端面ｗとの距離、及び、断面変化部１３の始端とその始端側の端面ｗとの距離は、互いに等しいことが望ましい。 Further, it is desirable that the axial range of the cross-section changing portion 13 includes the midpoint between the opposing end faces w and w of the projecting portions adjacent to each other in the axial direction, and further, the start end of the cross-section changing portion 13 and the start end side thereof. It is desirable that the distance to the end face w and the distance between the start end of the cross-section changing portion 13 and the end face w on the start end side are equal to each other.

さらに、断面変化部１３の軸方向範囲は、中空カムシャフト２０の種別を外観上で識別するための識別用突部２５の位置を避けて配置することが望ましい。あるいは、逆に、識別用突部２５は、断面変化部１３の軸方向範囲とは別の軸方向範囲に設けることが望ましい。 Further, it is desirable that the axial range of the cross-section changing portion 13 is arranged so as to avoid the position of the identification protrusion 25 for visually identifying the type of the hollow camshaft 20. Alternatively, conversely, it is desirable that the identification protrusion 25 is provided in an axial range different from the axial range of the cross-section changing portion 13.

この実施形態では、断面変化部１３は、軸方向に隣り合うフランジ部２４の端面ｗと、カム部２２の端面ｗとの間に配置されるようにしたが、これ以外にも、例えば、断面変化部１３を、ジャーナル部２３と同じ軸方向範囲に設定してもよい。この場合、断面変化部１３は、軸方向に隣り合うフランジ部２４の端面ｗとフランジ部２４の端面ｗとの間に配置されることとなるか、あるいは、断面変化部１３は、軸方向に隣り合うカム部２２の端面ｗとカム部２２の端面ｗとの間に配置されることとなる。 In this embodiment, the cross-section changing portion 13 is arranged between the end face w of the flange portions 24 adjacent to each other in the axial direction and the end face w of the cam portion 22, but in addition to this, for example, the cross section The changing portion 13 may be set in the same axial range as the journal portion 23. In this case, the cross-section changing portion 13 is arranged between the end face w of the flange portions 24 adjacent in the axial direction and the end face w of the flange portion 24, or the cross-section changing portion 13 is arranged in the axial direction. It will be arranged between the end surface w of the adjacent cam portions 22 and the end surface w of the cam portions 22.

また、ジャーナル部２３のフランジ部２４やカム部２２以外にも突出部が設けられている場合には、断面変化部１３は、そのフランジ部２４やカム部２２以外の突出部を避けて、軸方向に隣り合う突出部同士の端面ｗ，ｗ間に配置することが望ましい。 Further, when a protruding portion is provided in addition to the flange portion 24 and the cam portion 22 of the journal portion 23, the cross-section changing portion 13 avoids the protruding portion other than the flange portion 24 and the cam portion 22 and shafts. It is desirable to arrange the protrusions adjacent to each other in the direction between the end faces w and w.

この発明の中空カムシャフト２０は、通常のカムシャフトと同じく鋳造法により製造される。鋳造の際には、中空部１０に対応する形状の中子が用いられ、型枠の中に中子が配置され、溶湯が注入されて金属が固化した後に、中子をショットブラスト等により排除して、さらに、ジャーナル部２３やカム部２２、雌ネジ部１１等の加工を施して、中空カムシャフト２０を完成させている。 The hollow camshaft 20 of the present invention is manufactured by a casting method like a normal camshaft. At the time of casting, a core having a shape corresponding to the hollow portion 10 is used, the core is placed in the mold, the molten metal is injected and the metal is solidified, and then the core is removed by shot blasting or the like. Then, the journal portion 23, the cam portion 22, the female screw portion 11, and the like are further processed to complete the hollow camshaft 20.

中子は、接続部１２、断面変化部１３、大断面部１６の断面一定部１４、プラグ嵌込部１５に対応した形状とすることができるが、プラグ嵌込部１５を鋳造後の加工とすることもできる。 The core can have a shape corresponding to the connecting portion 12, the cross-section changing portion 13, the cross-section constant portion 14 of the large cross-section portion 16, and the plug fitting portion 15, but the plug fitting portion 15 can be processed after casting. You can also do it.

この実施形態では、断面変化部１３は、軸方向一端側から軸方向他端側に向かって、テーパ状に断面積が拡大するようにし、そのテーパの形状を直線状としたが、断面変化部１３の形状はこの実施形態に限定されない。例えば、断面変化部１３のテーパの形状を、その母線が円弧を描くような曲面状とすることも可能である。また、軸方向一端側から軸方向他端側に向かって、階段状に断面積が拡大するような形状も可能である。ただし、いずれの場合も、応力が集中するようなコーナー部、あるいは、先鋭な稜線を持つ角部を設けることは好ましくなく、断面変化部１３の全域、及び、接続部１２や大断面部１６との接続箇所において、できるだけ滑らかな面で連続していることが望ましい。 In this embodiment, the cross-sectional change portion 13 has a tapered cross-sectional area that expands from one end side in the axial direction to the other end side in the axial direction, and the shape of the taper is linear. The shape of 13 is not limited to this embodiment. For example, the shape of the taper of the cross-sectional change portion 13 can be a curved surface such that the generatrix draws an arc. Further, a shape in which the cross-sectional area expands stepwise from one end side in the axial direction to the other end side in the axial direction is also possible. However, in either case, it is not preferable to provide a corner portion where stress is concentrated or a corner portion having a sharp ridgeline, and the entire area of the cross-section changing portion 13 and the connecting portion 12 and the large cross-section portion 16 It is desirable that the connection points are continuous on a smooth surface as much as possible.

図３は、この発明の中空カムシャフト２０と、従来の中空カムシャフトの性能を比較するグラフ図である。図１における鎖線で示すラインが、従来の中空カムシャフト２０であり、実線で示すラインが、この発明の中空カムシャフト２０である。 FIG. 3 is a graph comparing the performance of the hollow camshaft 20 of the present invention and the conventional hollow camshaft. The line shown by the chain line in FIG. 1 is the conventional hollow camshaft 20, and the line shown by the solid line is the hollow camshaft 20 of the present invention.

図１中の断面Ａ，Ｂ，Ｃ，Ｄ，Ｅ，Ｆ，Ｇ，Ｈ，Ｉの各箇所における断面係数の比較を、図３（ａ）に示す。図１中の断面Ａ，Ｂ，Ｃ，Ｄ，Ｅ，Ｆ，Ｇ，Ｈ，Ｉの各箇所における断面二次モーメントの比較を、図３（ｂ）に示す。いずれの地点も、並列する棒グラフのうち、白抜きで示す左側の棒グラフが従来例を示し、グレーで示す右側の棒グラフがこの発明の実施形態を示すものである。 FIG. 3 (a) shows a comparison of the cross-section coefficients at each of the cross-sections A, B, C, D, E, F, G, H, and I in FIG. FIG. 3 (b) shows a comparison of the moments of inertia of area at each of the cross sections A, B, C, D, E, F, G, H, and I in FIG. At each point, among the parallel bar graphs, the bar graph on the left side shown in white shows a conventional example, and the bar graph on the right side shown in gray shows an embodiment of the present invention.

この発明では、中空部１０に大断面部１６を設けたことにより、従来の中空部よりも空洞の容積が大きくなっているが、いずれの地点においても、ほぼ同等の性能を発揮している。 In the present invention, since the hollow portion 10 is provided with the large cross-sectional portion 16, the volume of the cavity is larger than that of the conventional hollow portion, but almost the same performance is exhibited at any point.

３ ボルト
５ カムプーリ
１０ 中空部
１１ 雌ネジ部
１２ 接続部
１３ 断面変化部
１４ 断面一定部
１５ プラグ嵌込部
１６ 大断面部
２０ 中空カムシャフト
２１ ベース軸
２２ カム部
２３ ジャーナル部
２４ フランジ部
２５ 識別用突部
ｗ 端面
Ｒ アール部 3 Bolt 5 Cam pulley 10 Hollow part 11 Female thread part 12 Connection part 13 Cross-section change part 14 Cross-section constant part 15 Plug fitting part 16 Large cross-section part 20 Hollow camshaft 21 Base shaft 22 Cam part 23 Journal part 24 Flange part 25 For identification Protrusion w End face R R part

Claims (5)

軸方向に延びる中空部と、
中空部の軸方向一端の内面に形成された雌ネジ部と、
を備え、
前記中空部は、
前記雌ネジ部よりも他端側に一端側から他端側に向かって断面積が拡大する断面変化部と、
前記断面変化部よりも他端側全域に前記雌ネジ部よりも断面積が大きい大断面部と、
を備える中空カムシャフトであって、
軸方向に沿って軸心から離れる方向に突出する突出部が形成され、
前記突出部は、軸方向に沿って断続的に配置されたカム部と、軸方向に沿って断続的に配置されたジャーナル部の軸方向両側に配置される位置決めフランジ部と、を含み、
前記断面変化部は、軸方向に隣り合う前記突出部同士の対向する端面間に配置されるとともに対向する前記突出部は前記カム部と前記位置決めフランジ部である中空カムシャフト。 Hollow part extending in the axial direction and
A female threaded portion formed on the inner surface of one end of the hollow portion in the axial direction,
With
The hollow part is
A cross-sectional change portion in which the cross-sectional area expands from one end side to the other end side on the other end side of the female screw portion.
A large cross-sectional portion having a larger cross-sectional area than the female screw portion over the entire other end side of the cross-sectional change portion,
It is a hollow camshaft equipped with
A protrusion is formed that projects along the axial direction away from the axial center.
The protruding portion includes a cam portion which is intermittently arranged along the axial direction, and a positioning flange which is arranged axially on both sides of the intermittently arranged journal in the axial direction, and
The cross-sectional change portion is arranged between the opposing end faces of the projecting portions adjacent to each other in the axial direction, and the projecting portions facing each other are a hollow camshaft which is a cam portion and a positioning flange portion. 前記大断面部は、
軸方向他端に形成されたプラグ嵌込部と、
前記断面変化部から前記プラグ嵌込部まで同一の断面で継続する断面一定部と、
を備える請求項１に記載の中空カムシャフト。 The large cross section is
With the plug fitting part formed at the other end in the axial direction,
A constant cross-section that continues in the same cross-section from the cross-section change portion to the plug fitting portion,
The hollow camshaft according to claim 1. 前記断面変化部は、テーパ状に断面積が拡大する
請求項１又は２に記載の中空カムシャフト。 The hollow camshaft according to claim 1 or 2, wherein the cross-sectional area is expanded in a tapered shape. 前記突出部の端面の裾部に、半径方向内側に向かうにつれて軸方向へ湾曲してその終端部で前記突出部の側方の円筒面に接続されるアール部を備え、
前記断面変化部は、軸方向に隣り合う前記アール部同士の前記終端部間に配置される
請求項１〜３の何れか１項に記載の中空カムシャフト。 The hem of the end face of the protrusion is provided with a rounded portion that curves axially inward in the radial direction and is connected to the lateral cylindrical surface of the protrusion at its end.
The hollow camshaft according to any one of claims 1 to 3, wherein the cross-section changing portion is arranged between the terminal portions of the rounded portions adjacent to each other in the axial direction. 前記断面変化部は前記ジャーナル部と同じ軸方向範囲にある
請求項１〜４の何れか１項に記載の中空カムシャフト。 The hollow camshaft according to any one of claims 1 to 4, wherein the cross-section changing portion is in the same axial range as the journal portion.
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JPS63134806A (en) * 1986-11-27 1988-06-07 Nippon Piston Ring Co Ltd Manufacture of hollow cam shaft
JPH01115803U (en) * 1988-01-30 1989-08-04
US5778841A (en) * 1997-02-26 1998-07-14 Cummins Engine Company, Inc. Camshaft for internal combustion engines
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