JP2003166601A - Gear pair with parallel axes - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gear pair with parallel axes having parallel axes of two meshing gears that can solve the disadvantage of a conventional a gear pair with parallel axes comprising spur gears that the application of crowning to tooth surfaces against uneven contact occurring when the axes deviate from the parallel state requires labor. <P>SOLUTION: In the gear pair with parallel axes, tooth surfaces are formed axially on outer circumferences of truncated cones of the same cone angle, a small end side tooth tip has a larger tooth thickness than a large end side tooth tip and a large end side tooth root has a smaller tooth thickness than a smaller end side tooth root, a tooth surface profile is twisted axially from the small end to the large end, and the small end side tooth surface of one gear is meshed with the large end side tooth surface of the other gear with a backlash. Without crowning, even when the axes of the gears deviate from the parallel state, the gears are in contact at the middle along the tooth trace to produce an equivalent effect to crowned ones, and tooth surface machining can be performed similarly to the spur gear tooth profile machining only by an inclination of a hob or a screw type grinding wheel at the cone angle θto a gear blank. <P>COPYRIGHT: (C)2003,JPO

Description

【発明の詳細な説明】 【０００１】 【発明の属する技術分野】本発明は、平行に配置された
回転軸に取り付けられ、動力を伝達する歯車（以下平行
軸歯車という）に係わり、特に外形形状が円錐台にさ
れ、歯面が外周面に沿って軸方向に形成されるととも
に、歯形加工をしただけで歯すじ修整（クラウニング）
を行わなくても、２つの歯車の回転軸が平行状態からず
れても、互いに噛み合った２つの歯車の歯面に片当たり
が生じないようにされ、歯形加工のみで歯面に歯すじ修
整クラウニングを施工したものと同等な効果が得られる
ようにした平行軸歯車に関する。 【０００２】 【従来の技術】例えば、直交して配置されたウォームと
ウォームホィールとが噛合する歯面においては、組み立
て関係位置の狂いによる当たりの低下を防ぎ、また潤滑
油を歯面の噛み合い部へ引き込み易くするために、両歯
車の歯面にクラウニングを施工することが行われてい
る。 【０００３】また、平行軸歯車においても軸方向の径が
同じにされた円柱の外周面に軸方向と平行に形成され、
歯すじ（歯幅）方向の歯面断面形状が同じにされて、回
転軸軸心３，４が完全な平行状態で配置された、図３に
示す平歯車１ａ，２ｂにおいても、製造公差や運転中の
荷重により、図４に示す様に２つの歯車の回転軸軸心
３，４方向が完全な平行状態から外れ、平行状態からの
ずれδが生じると、完全な平行状態では歯すじ方向７全
体に接触する歯当たり部５が生じていた平歯車１ａと平
歯車２ｂとの歯面６が、図６に示すように歯すじ方向７
の端部のみに歯当たり部５が生じる、所謂片当たりが生
じるようになる。 【０００４】この片当たりが生じないようにするため
に、図７に示すように、平歯車１ａ，２ｂにおいても歯
面６にクラウニングを施工し、２つの平歯車１ａ，２ｂ
の軸心方向３，４が完全な平行状態からずれた場合に
は、平歯車１ａと平歯車２ｂとの歯面６を歯すじ方向中
央部１８で接触させるようにすることが行われている。
即ち、図７の点線で示すように歯すじ方向７に一様な歯
厚８で形成されている歯面断面形状を、歯すじ方向中央
部１８から端部に向け、歯すじ方向７の同一位置では歯
面６上端から歯面６下端まで同一厚み削りとり、しかも
歯すじ方向中央部１８から端部に向け歯厚８が滑らかに
減少するように連続的に減少させて、図７の実線で示す
ように歯すじ方向７端部の厚みが、中央部１８よりも凹
になるようにする歯すじ修整を行うようにしたものであ
る。 【０００５】このようなクラウニング施工作業は、製作
する歯車の歯面と同一形状の刃先形状にされたシェービ
ングカッター等を回転軸軸心方向の一方向に作動させ
て、平歯車を製作する素材である円柱状の歯車ブランク
を、外周面側から削り取り歯形を形成していく歯形加工
とは異なり、作業自体が特殊なものとなり、また施工作
業を行う時の基準となるものがないために、施工作業が
難しく、さらには、高い施工精度が要求されるために、
その作業には多大の労力を要するとともに、高い熟練度
を要する作業となる。 【０００６】 【発明が解決しようとする課題】本発明は、作業に多大
の労力を要するとともに、高い熟練度を要する歯面のク
ラウニング施工を必要とすることなく、従来から平歯車
等で行われている歯面加工と同等な加工を行うだけで、
噛合する２つの歯車の軸心方向が完全な平行状態から外
れた場合においても、歯面にクラウニング施工をした場
合と同様に片当たりが生じることなく、２つの歯車の歯
面が歯すじ方向中央部で接触できるようにした平行軸歯
車の提供を課題とする。 【０００７】 【課題を解決するための手段】このため、本発明の平行
軸歯車は次の手段とした。噛み合わせる２つの歯車の軸
方向を平行に配置して、相互に動力を伝達するようにし
た平行軸歯車において、歯車の歯面が同一円錐角を有す
る円錐台の外周面軸方向に形成され、円錐台の大径側で
ある大端側に形成される歯先における歯厚よりも小径側
である小端側に形成される歯先の歯厚を大きくし、小端
側に形成される歯元における歯厚よりも大端側に形成さ
れる歯元の歯厚を小さくして、小端側の歯先から歯元に
向う歯たけ方向に形成される全体的な傾斜が、大端側の
歯先から歯元に向けて形成される傾斜より急峻にされ
て、歯面断面形状が小端側から大端側に向けて歯面断面
形状が順次捩じられた状態で軸方向に設けられるととも
に、バックラッシュを有して一方の歯車の小端側歯面を
他方の歯車の大端側歯面に噛み合せ作動させるように、
対向させて２つの歯車を配置するものとした。 【０００８】これにより、加工作業が難しく加工精度を
上げる必要があるため、多大の労力を必要とし、熟練度
を要し特殊の作業になっていた歯面にクラウニング施工
を行うことなく、２つの歯車の軸心方向が完全な平行状
態から外れた場合においても、２つの歯車の歯当たり部
５は、歯すじ方向７の中央の一点に生じることになり、
歯面に片当たりが生じるのを防止でき、平歯車１ａ，２
ｂにおいてクラウニング施工をしたものと等価な効果が
得られるものにできる。また、歯形加工は、従来から前
述した平歯車の歯形加工において行なわれているホブ、
又はネジ型砥石による加工を、平行軸歯車を製作する円
錐台形状にされた素材である歯車ブランクに対して、ホ
ブ又はネジ型砥石等の加工治具の移動方向を円錐角θ分
だけ僅かに傾け、又は歯面加工時の歯車ブランクの姿勢
をθだけ傾けるだけで、平歯車１ａ，２ｂの歯形加工と
同様に施工することによりでき、極めて容易になる。 【０００９】 【発明の実施の形態】以下、本発明の平行軸歯車の実施
の一形態を図面に基づき説明する。図１は本発明の平行
軸歯車の実施の第１形態を示す一対の平行軸歯車の軸心
を含む面での断面図、図２は図１に示す歯車の歯面形状
を示す斜視図である。 【００１０】図１において、１２ｃは外形が円錐角θの
円錐台にされ、外側面に歯面１６が形成された（平行
軸）歯車、１３ｄは外形が歯車１２ｃと同様に円錐台の
外形形状にされ、歯車１２ｃと同様に歯面１７が外側面
に形成された（平行軸）歯車である。この歯面１６、歯
面１７は、円錐台の軸心方向の一端である径が小さくさ
れている端部の小端１０の歯厚８中心と、他端である径
が大きくされている端部の大端１１の歯厚８中心とが、
円錐台の軸心まわりに同一位相をなし、歯車１２ｃ及び
歯車１３ｄをそれぞれ回転させる回転軸の軸心１４，１
５方向と円錐台の傾斜角θをなして、外周面に沿って軸
方向に設けられるとともに、円錐角θの大きさは５°程
度以下になるようにしている。 【００１１】なお、円錐角θの大きさは理論的に４５°
程度にすることも可能であるが、１〜２°程度のもので
も十分使用でき、さらには歯車１２ｃ、歯車１３ｄを形
成する円錐台は、図に示すように同一形状のものとする
必要はなく、円錐角θが同一にされていれば、大きさ、
換言すれば２つの歯車の大端１１，小端１０の径をそれ
ぞれ異るものにすることもできるものである。 【００１２】また、歯車１２ｃと歯車１３ｄとは、歯車
１２ｃの小端１０部に形成された歯面１６が歯車１３ｄ
の大端１１部に形成された歯面１７に噛み合うととも
に、歯車１２ｃの大端１１部に形成された歯面１６が歯
車１３ｄの小端１０部に形成された歯面１７に噛み合う
ように、相互に対向状態で配置され、歯車１２ｃと歯車
１３ｄとの回転軸軸心１４，１５が完全に平行状態にな
るようにして、平行軸歯車を形成するようにしている。 【００１３】また、歯車１２ｃ及び歯車１３ｄの外側面
に形成される歯面１６，１７の歯すじ（歯幅）方向７の
断面形状は、一様ではなく、図２に示すように小端１０
側から大端１１側に向けて捩じりが付されおり、図７に
おいて説明した平歯車１ａ，２ｂの歯面端部の歯厚８
が、歯すじ方向中央部１８の歯厚に対して凹になるよう
にして行なう歯面修整（クラウニング）を施工したとき
と同じ効果が得られるようにしている。 【００１４】すなわち、図３に示すように、軸心３，４
方向に径が等しい円柱の外周面軸心方向と平行な歯面６
が、軸心３，４と平行に形成された平歯車１ａ，２ｂか
らなる平行軸歯車であれば、回転軸軸心３，４を含む面
における歯面断面形状は長方形であり、歯すじ方向の歯
面断面形状が歯すじ方向７に同一であっても、歯面６の
噛み合いには何ら不具合はないが、本実施の形態のよう
に断面形状が台形にされ、外形が円錐台にされて外周面
に沿って軸心１４，１５方向と円錐角θをなして歯すじ
方向７に歯面を形成するようにした場合には、小端１０
側と大端１１側では角速度が異なる。 【００１５】このために、小端１０側の歯先の歯厚８を
大きく、歯元の歯厚８を小さくするとともに、大端１１
側の歯先の歯厚８を小端側１０から徐々に小さくなるも
のにし、また歯元の歯厚８を小端１０側から徐々に大き
くなるようにして、歯面１６，１７の上端と下端との間
の歯たけ９方向に円弧状に形成される全体的な歯面傾斜
を、小端１０側では急峻にし、大端１１側では緩やかな
ものにし、歯すじ方向７の歯面断面形状を一様でなく、
歯すじ方向７に歯面断面形状が捩じられて形成されて、
角速度が異なっても歯面１６，１７の噛み合いに不具合
が生じないようにしている。 【００１６】このようにして、僅かな円錐角θを付した
円錐形の歯車１２ｃ，１３ｄの一対を、図１に示すよう
にバックラッシュを有し対向状態にして配置し、作動さ
せるようにすることにより、前述した、片当りを防止す
るために平歯車１ａ，２ｂで施工される特殊な作業必要
とするクラウニングを行なうことなく、従来の平歯車１
ａ，２ｂの歯面６に施工されているクラウニングと等価
な効果が得られるものにすることができる。 【００１７】すなわち、このように円錐台状の外側面に
歯面１６，１７を形成するようにした歯車１２ｃ、歯車
１３ｄでは、歯面断面形状は歯すじ方向７に沿って一様
でない上に、歯車１２ｃの小端１０側の歯面１６を歯車
１３ｄの大端１１側の歯面１７に噛み合わせ、歯車１２
ｃの大端１１側の歯面１６を歯車１３ｄの小端１０側の
歯面１７に噛み合わせ、歯車１２ｃと歯車１３ｄとを向
かい合わせた状態に配置して使用すれば、作動時の歯車
１２ｃ、歯車１３ｄの歯面１６，１７は、歯車１２ｃと
歯車１３ｄとの回転軸軸心１４，１５方向の完全な平行
状態が崩れた場合においても、歯すじ方向７の中央の一
点で接触することになり、片当たりを防止でき平歯車１
ａ、２ｂにおいてクラウニング施工をしたときと等価な
効果が得られるものにできる。 【００１８】また、本実施の形態の平行軸歯車の歯形加
工は、加工作業が難しく加工精度を上げる必要があるた
めに、作業には多大の労力を必要としていたクラウニン
グ施工が不要になり、従来から平歯車１ａ，２ｂの歯形
加工において行われているホブ、又はネジ型砥石の作動
方向を歯車ブランクの軸心方向に対して円錐角θ分だ
け、僅かに傾け外周面側からシェービング加工するだけ
で製作することができるようになり、加工が極めて容易
になる。 【００１９】 【発明の効果】以上説明したように、本発明の平行軸歯
車は、歯面が同一円錐角を有する２つの円錐台の外周面
軸方向にそれぞれ形成され、円錐台の大端側歯先の歯厚
よりも小端側の歯先の歯厚を大きく、小端側の歯元の歯
厚よりも大端側の歯元の歯厚を小さくし、歯先から歯元
に向けて形成された小端側の傾斜が大端側の傾斜より急
峻にされて、小端側から大端側に向けて歯面断面形状が
順次捩じられて軸方向に設けられ、バックラッシュを有
して一方の歯車の小端側歯面を他方の歯車の大端側歯面
に噛み合わせて対向させ配置するものとした。 【００２０】これにより、加工作業が難しく加工精度を
上げる必要があるため、多大の労力を必要とし、熟練度
を要し特殊の作業になっていたクラウニング施工を行う
ことなく、２つの歯車の軸心が平行状態から外れた場合
でも、歯車は歯すじ方向中央の一点で接触し、歯面片当
たりが生じることがなく、クラウニング施工をしたもの
と等価な効果が得られる。また、クラウニング施工は、
平歯車の歯形加工におけるホブ、又はネジ型砥石による
加工を、歯車ブランクに対してホブ又はネジ型砥石を円
錐角θ分だけ僅かに傾けるだけで、平歯車の歯型の加工
と同様にして施工でき極めて容易になる。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gear (hereinafter referred to as a parallel shaft gear) mounted on a rotating shaft arranged in parallel and transmitting power, and particularly to an outer shape. Is made into a truncated cone, and the tooth surface is formed in the axial direction along the outer peripheral surface.
Even if the rotation shafts of the two gears are not parallel to each other, the tooth surfaces of the two gears meshing with each other are prevented from being brought into contact with each other. The present invention relates to a parallel shaft gear capable of obtaining the same effect as that obtained by constructing the shaft. 2. Description of the Related Art For example, in a tooth surface where a worm and a worm wheel arranged orthogonally mesh with each other, a drop in contact due to a deviation of an assembling position is prevented, and lubricating oil is applied to a meshing portion of the tooth surface. In order to make the gears easily retractable, crowning is performed on the tooth surfaces of both gears. [0003] Also, in the parallel shaft gear, the diameter in the axial direction is formed parallel to the axial direction on the outer peripheral surface of a cylinder having the same diameter.
The spur gears 1a and 2b shown in FIG. 3 in which the tooth surface cross-sectional shape in the tooth trace (tooth width) direction is the same and the rotation axis axes 3 and 4 are arranged in a completely parallel state are also used. Due to the load during operation, as shown in FIG. 4, the directions of the rotating shaft axes 3 and 4 of the two gears deviate from a completely parallel state and a deviation δ from the parallel state occurs. As shown in FIG. 6, the tooth surface 6 of the spur gear 1a and the spur gear 2b where the tooth contact portion 5 contacting the whole
A so-called one-sided contact occurs, in which the tooth contact portion 5 is formed only at the end of the contact. As shown in FIG. 7, crowning is applied to the tooth surface 6 of the spur gears 1a and 2b so as to prevent the one-side contact from occurring, and the two spur gears 1a and 2b are crowned.
When the axial directions 3 and 4 are shifted from the completely parallel state, the tooth surfaces 6 of the spur gear 1a and the spur gear 2b are brought into contact with each other at the central portion 18 in the tooth streak direction. .
That is, as shown by the dotted line in FIG. 7, the tooth surface cross-sectional shape formed with a uniform tooth thickness 8 in the tooth lead direction 7 from the central part 18 in the tooth lead direction to the end is the same in the tooth lead direction 7. In the position, the same thickness is cut from the upper end of the tooth surface 6 to the lower end of the tooth surface 6, and the tooth thickness 8 is continuously reduced so that the tooth thickness 8 is smoothly reduced from the central portion 18 to the end in the tooth trace direction. As shown in the figure, the tooth streak is modified so that the thickness at the end in the tooth streak direction 7 is more concave than the center part 18. [0005] Such a crowning work is performed by using a material for producing a spur gear by operating a shaving cutter or the like having the same cutting edge shape as the tooth surface of the gear to be produced in one direction along the rotation axis. Unlike the tooth profile machining in which a certain cylindrical gear blank is shaved from the outer peripheral surface side to form a tooth profile, the work itself becomes special and there is no standard that can be used for construction work. Because work is difficult and high construction accuracy is required,
The work requires a great deal of labor and requires a high level of skill. [0006] The present invention requires a great deal of labor for the operation, and does not require crowning of the tooth surface which requires a high level of skill. Just perform the same processing as the tooth surface processing
Even when the axial directions of the two gears meshing with each other deviate from the completely parallel state, the tooth surfaces of the two gears are positioned in the center in the direction of the tooth in the same direction as when the crowning is performed on the tooth surfaces. An object of the present invention is to provide a parallel shaft gear that can be brought into contact at a portion. [0007] Therefore, the parallel shaft gear of the present invention has the following means. In a parallel shaft gear in which the axial directions of two gears meshing with each other are arranged in parallel to transmit power to each other, the tooth surfaces of the gears are formed in the axial direction of the outer peripheral surface of the truncated cone having the same cone angle, The tooth thickness of the tip formed on the small end side, which is the smaller diameter side, is larger than the tooth thickness of the tip formed on the large end side, which is the larger diameter side of the truncated cone, and the teeth formed on the small end side By making the tooth thickness of the dedendum formed on the large end side smaller than the original tooth thickness, the overall inclination formed in the tooth setting direction from the tip of the small end side toward the dedendum is larger than the large end side. It is made steeper than the slope formed from the tip of the tooth toward the root of the tooth, and the tooth surface cross-sectional shape is provided in the axial direction with the tooth surface cross-sectional shape sequentially twisted from the small end side to the large end side And has a backlash to engage the small end tooth flank of one gear with the large end tooth flank of the other gear. Sea urchin,
Two gears are arranged to face each other. As a result, the machining operation is difficult and it is necessary to increase the machining accuracy. Therefore, a large amount of labor is required, and without performing the crowning work on the tooth surface, which requires skill and is a special operation, the two Even when the axial directions of the gears deviate from the completely parallel state, the tooth contact portions 5 of the two gears will be formed at a central point in the tooth lead direction 7,
It is possible to prevent the occurrence of one-side contact on the tooth surface, and the
In b, an effect equivalent to that obtained by crowning can be obtained. In addition, the tooth profile machining is performed by a hob, which is conventionally performed in the tooth profile machining of the spur gear described above.
Alternatively, processing with a screw-type grindstone, the movement direction of a processing jig such as a hob or a screw-type grindstone with respect to a gear blank, which is a frustum-cone-shaped material for producing a parallel shaft gear, is slightly shifted by a cone angle θ. By simply inclining or inclining the attitude of the gear blank at the time of tooth flank machining by θ, it is possible to carry out the construction in the same manner as the tooth profile machining of the spur gears 1a and 2b, which is extremely easy. An embodiment of a parallel shaft gear according to the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a plane including the axis of a pair of parallel shaft gears showing a first embodiment of the parallel shaft gear of the present invention, and FIG. 2 is a perspective view showing the tooth surface shape of the gear shown in FIG. is there. In FIG. 1, reference numeral 12c denotes a gear whose outer shape is a truncated cone having a cone angle θ and a tooth surface 16 is formed on the outer surface (parallel shaft), and reference numeral 13d denotes an outer shape of a truncated cone like the gear 12c. This is a (parallel shaft) gear having a tooth surface 17 formed on the outer surface in the same manner as the gear 12c. The tooth surface 16 and the tooth surface 17 are formed at the center of the tooth thickness 8 of the small end 10 at the end of the truncated cone, which is one end in the axial direction, and at the end at the other end. The tooth thickness 8 center of the large end 11 of the part is
The axes 14, 1 of rotating shafts which have the same phase around the axis of the truncated cone and rotate the gears 12c and 13d, respectively.
It is provided in the axial direction along the outer peripheral surface at an inclination angle θ of the truncated cone with the five directions, and the magnitude of the cone angle θ is set to about 5 ° or less. The cone angle θ is theoretically 45 °.
Although it is also possible to use about 1 to 2 °, the frustums of the gears 12c and 13d need not have the same shape as shown in the figure. , If the cone angle θ is the same, the size,
In other words, the diameters of the large end 11 and the small end 10 of the two gears can be different from each other. The gear 12c and the gear 13d have a tooth surface 16 formed at the small end 10 of the gear 12c.
So that the tooth surface 16 formed on the large end 11 of the gear 12c meshes with the tooth surface 17 formed on the small end 10 of the gear 13d. The rotating shafts 14 and 15 of the gear 12c and the gear 13d are arranged to face each other so that the rotating shafts 14 and 15 are completely parallel to each other to form a parallel shaft gear. The cross-sectional shape of the tooth surfaces 16 and 17 formed on the outer surfaces of the gears 12c and 13d in the tooth streak (teeth width) direction 7 is not uniform, and as shown in FIG.
From the side to the large end 11 side, and the tooth thickness 8 at the end of the tooth surface of the spur gears 1a and 2b described in FIG.
However, the same effect as when the tooth surface modification (crowning) is performed so as to be concave with respect to the tooth thickness of the central portion 18 in the tooth streak direction is obtained. That is, as shown in FIG.
Tooth surface 6 parallel to the axial direction of the outer peripheral surface of a cylinder having the same diameter in the direction
Is a parallel shaft gear composed of spur gears 1a and 2b formed parallel to the shaft centers 3 and 4, the cross-sectional shape of the tooth surface in the plane including the rotation shaft axes 3 and 4 is rectangular, and Even if the tooth surface cross-sectional shape is the same in the tooth lead direction 7, there is no problem in the meshing of the tooth surface 6, but the cross-sectional shape is trapezoidal as in the present embodiment, and the external shape is frustoconical. When the tooth surface is formed in the tooth lead direction 7 at a cone angle θ with the directions of the axial centers 14 and 15 along the outer peripheral surface, the small end 10
The angular velocity is different between the side and the large end 11 side. For this purpose, the tooth thickness 8 at the tip of the small end 10 is increased, the tooth thickness 8 at the root is reduced, and
The tooth thickness 8 at the tip of the tooth is gradually reduced from the small end 10, and the tooth thickness 8 at the base of the tooth is gradually increased from the small end 10, so that The overall tooth surface inclination, which is formed in an arc shape in the direction of the tooth gap 9 between the lower end and the lower end, is made steeper at the small end 10 side and gentle at the large end 11 side. The shape is not uniform,
The tooth flank cross-sectional shape is formed by being twisted in the tooth lead direction 7,
Even if the angular velocities are different, no problem occurs in meshing of the tooth surfaces 16 and 17. In this manner, a pair of conical gears 12c and 13d having a slight cone angle θ are arranged and operated in a facing state with a backlash as shown in FIG. Thus, the conventional spur gear 1 can be used without performing the above-described crowning, which requires special work to be performed with the spur gears 1a and 2b to prevent the one-side contact.
An effect equivalent to the crowning applied to the tooth surfaces 6 of a and 2b can be obtained. That is, in the gears 12c and 13d in which the tooth surfaces 16 and 17 are formed on the outer surface of the truncated cone as described above, the tooth surface cross-sectional shape is not uniform along the tooth streak direction 7. The tooth surface 16 on the small end 10 side of the gear 12c meshes with the tooth surface 17 on the large end 11 side of the gear 13d.
If the tooth surface 16 on the large end 11 side of the gear c is meshed with the tooth surface 17 on the small end 10 side of the gear 13d and the gear 12c and the gear 13d are arranged to face each other, the gear 12c at the time of operation is used. The tooth surfaces 16 and 17 of the gear 13d contact at one point in the center in the tooth trace direction 7 even when the completely parallel state of the rotation axes 14 and 15 of the gear 12c and the gear 13d is broken. Spur gear 1
It is possible to obtain an effect equivalent to that obtained when the crowning is performed in a and 2b. Further, in the tooth profile machining of the parallel shaft gear according to the present embodiment, since the machining operation is difficult and it is necessary to increase the machining accuracy, the crowning work which requires a large amount of work is not required, and the conventional method is not required. The operating direction of the hob or screw-type grindstone performed in the tooth profile machining of the spur gears 1a and 2b is slightly inclined by the conical angle θ with respect to the axial direction of the gear blank, and shaving is performed from the outer peripheral surface side. And the processing becomes extremely easy. As described above, the parallel shaft gear according to the present invention is formed in the axial direction of the outer peripheral surface of two truncated cones having tooth surfaces having the same cone angle. The tooth thickness at the tip of the small end is larger than the tooth thickness of the tip, and the tooth thickness at the large end is smaller than the tooth thickness at the small end. The inclination of the formed small end is made steeper than the inclination of the large end, and the tooth surface cross-sectional shape is sequentially twisted from the small end to the large end so as to be provided in the axial direction to reduce backlash. In this case, the small end side tooth surface of one gear is meshed with and opposed to the large end side tooth surface of the other gear. As a result, the machining operation is difficult and it is necessary to increase the machining accuracy. Therefore, a large amount of labor is required, and the two gear shafts are required without performing the crowning work which requires skill and is a special operation. Even when the center deviates from the parallel state, the gears come into contact at one point in the center in the direction of the tooth traces, and no contact of the tooth surface occurs, so that an effect equivalent to that obtained by crowning is obtained. Also, the crowning construction
Processing with a hob or screw-type grindstone in spur gear tooth profile processing is performed in the same way as spur gear tooth pattern processing, by slightly tilting the hob or screw type grindstone with respect to the gear blank by the cone angle θ. It becomes extremely easy.

【図面の簡単な説明】 【図１】本発明の平行軸歯車の実施の第１形態を示す縦
断面図、 【図２】図１に示す歯面の拡大形状を示す斜視図、 【図３】平行軸歯車の一例である平歯車を示す縦断面
図、 【図４】図３に示す平歯車の軸心が完全平行状態からず
れた状態を示す縦断面図、 【図５】図３に示す状態における２つの平歯車の歯当た
り部が歯すじ方向全体に接触している状態を示す斜視
図、 【図６】図４に示す状態における２つの平歯車の歯当た
り部が片当たりしている状態を示す斜視図、 【図７】平歯車の歯面にクラウニング施工をしたときの
斜視図である。 【符号の説明】 １ａ （平）歯車 ２ｂ （平）歯車 ３，４ 回転軸軸心 ５ 歯当たり部 ６ 歯面 ７ 歯すじ（歯幅） ８ 歯厚 ９ 歯たけ １０ 小端 １１ 大端 １２ｃ （平行軸）歯車 １３ｄ （平行軸）歯車 １４，１５ 回転軸軸心 １６，１７ 歯面 １８ 歯すじ方向中央部 δ 回転軸軸心の平行状態からのずれ θ 円錐角BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view showing a first embodiment of a parallel shaft gear of the present invention; FIG. 2 is a perspective view showing an enlarged shape of a tooth surface shown in FIG. 1; FIG. 4 is a longitudinal sectional view showing a spur gear as an example of a parallel shaft gear; FIG. 4 is a longitudinal sectional view showing a state where the axis of the spur gear shown in FIG. 3 is shifted from a completely parallel state; FIG. 6 is a perspective view showing a state in which the tooth contact portions of two spur gears in the state shown are in contact with the entire tooth trace direction. FIG. 7 is a perspective view when crowning is performed on the tooth surface of the spur gear. [Description of Signs] 1a (Spur) gear 2b (Spur) gear 3, 4 Rotary shaft axis 5 Tooth contact portion 6 Tooth surface 7 Tooth line (tooth width) 8 Tooth thickness 9 Tooth height 10 Small end 11 Large end 12c ( (Parallel axis) gear 13d (Parallel axis) gear 14, 15 Rotation axis 16,16 Tooth surface 18 Central part in the tooth trace direction δ Deviation of the rotation axis from the parallel state θ Cone angle

Claims (1)

【特許請求の範囲】 【請求項１】 噛み合わせる２つの歯車の軸心方向を平
行に配置して相互に動力を伝達する平行軸歯車におい
て、前記歯車の歯面が同一円錐角を有する円錐台の外周
面に形成され、前記円錐台の大端側に形成される歯先の
歯厚よりも小端側の歯先の歯厚を大きくし、小端側の歯
元の歯厚よりも大端側の歯元の歯厚を小さくして、小端
側から大端側に向けて歯面断面形状を順次捩じって軸方
向に設けられるとともに、バックラッシュを有して一方
の歯車の小端側歯面を他方の歯車の大端側歯面に噛み合
わせるように前記歯車を配置したことを特徴とする平行
軸歯車。Claims: 1. A parallel shaft gear for transmitting power mutually by arranging two gears meshing with each other with their axial directions parallel to each other, wherein the tooth surfaces of the gears have the same cone angle. Formed on the outer peripheral surface of the tooth, the tooth thickness of the tooth tip on the small end side being larger than the tooth thickness of the tooth tip formed on the large end side of the truncated cone, and larger than the tooth thickness of the tooth root on the small end side. The tooth thickness at the root side at the end side is reduced, and the tooth surface cross-sectional shape is sequentially provided in the axial direction from the small end side to the large end side, and is provided in the axial direction. A parallel shaft gear, wherein the gear is arranged so that the small end side tooth surface meshes with the large end side tooth surface of the other gear.