JP3704946B2

JP3704946B2 - Permanent magnet type eddy current reducer

Info

Publication number: JP3704946B2
Application number: JP10201798A
Authority: JP
Inventors: 徹桑原
Original assignee: Isuzu Motors Ltd
Current assignee: Isuzu Motors Ltd
Priority date: 1998-03-30
Filing date: 1998-03-30
Publication date: 2005-10-12
Anticipated expiration: 2018-03-30
Also published as: JPH11285234A

Description

【０００１】
【発明の属する技術分野】
本発明は主として大型車両の摩擦ブレーキを補助する渦電流減速装置、特に案内筒から強磁性板が脱落しないようにした永久磁石式渦電流減速装置に関するものである。
【０００２】
【従来の技術】
本出願人の出願である特願平 8-293,354号に開示される永久磁石式渦電流減速装置によれば、ほぼ長方形の強磁性板（ポールピース）の断面形状を、制動ドラムに対向する外面が内面よりも短辺になる台形にすることにより制動力を向上させることができる。上述の渦電流減速装置では断面長方形の内空部を有する案内筒の内部に、永久磁石（以下これを単に磁石という）を支持する磁石支持筒が封じ込まれ、アルミニウム鋳物などの非磁性体からなる案内筒の外周壁部に、磁石に対向し得る強磁性板が鋳込まれるか、オーステナイト系のステンレスからなる案内筒の外周壁部に強磁性板が溶接される。磁石支持筒を軸方向または周方向へ移動することにより制動と非制動の切換えが達せられる。強磁性板の断面形状を台形にすることにより、磁石から強磁性板を経て回転する制動ドラムへ向う磁束を絞り込んで磁束密度を大きくし、制動ドラムに発生する渦電流量を増大させて制動力を高める。
【０００３】
しかし、強磁性板の面積が磁石の方へ広がつた断面台形であると、強磁性板を案内筒へ鋳込みにくく、強磁性板の内面が磁石に重なる制動時、強磁性板が磁石へ吸引されて案内筒から抜け出すことがある。また修理点検のために制動ドラムを外した時にも強磁性板が案内筒から抜けやすい。
【０００４】
【発明が解決しようとする課題】
本発明の課題は上述の問題に鑑み、案内筒から強磁性板が脱落しないようにした永久磁石式渦電流減速装置を提供することにある。
【０００５】
【課題を解決するための手段】
上記課題を解決するために、本発明の構成は回転軸に結合した導体からなる制動ドラムの内部に、非磁性体からなりかつ断面長方形の内空部を有する不動の案内筒を同軸に配設し、前記案内筒の制動ドラムと対向する外周壁部に周方向等間隔に多数の強磁性板を結合し、前記案内筒の前記内空部に軸方向移動可能または回動可能に支持した少くとも１つの磁石支持筒に、前記強磁性板に対する極性が周方向に交互に異なるよう永久磁石を結合し、前記永久磁石が前記強磁性板と全面的に対向する制動位置と前記永久磁石が前記強磁性板と全面的には対向しない非制動位置とに前記磁石支持筒を移動させるアクチユエータを備えてなる永久磁石式渦電流減速装置において、型鍛造される前記強磁性板は型合せ面から制動ドラムに対向する外面に至る周方向端部の壁面を、型合せ面から前記外面へ近づくにつれて周方向の寸法が次第に短くなるように傾斜させ、型合せ面から磁石に対向する内面に至る周方向端部の壁面を、型合せ面から前記内面へ近づくにつれて周方向の寸法が次第に短くなるように傾斜させ、型合せ面の周縁部の少くとも一部に前記強磁性板の内方への抜けを阻止する突条からなる抜止め壁を備えたことを特徴とする。
【０００６】
【発明の実施の形態】
本発明では強磁性板（ポールピース）が磁石の吸引力により案内筒から抜けないように、強磁性板に抜止め壁を設ける。強磁性板は中間の厚さつまり型合せ面（パーテイングライン）から外側の部分、すなわち外半部の断面を台形にし、型合せ面の内半部は従来と同様にほぼ長方形にする。換言すれば、強磁性板の型合せ面の外半部の周方向端部または軸方向端部の壁面を傾斜させる。また、強磁性板が磁石の吸引力により案内筒から抜けないように、強磁性板に型合せ面に沿つて突条（リード）を設ける。ここで、型合せ面とは強磁性板の鍛造または鋳造に用いる上型と下型との境界面をいうことにする。
【０００７】
【実施例】
図１は本発明が適用される渦電流減速装置の正面断面図、図２は同側面断面図である。渦電流減速装置は制動ドラム１３を回転軸４に結合される。このため、変速機の歯車箱２の端壁に軸受３により支持されかつ端壁から突出する出力回転軸４に、スプライン孔５ａを有する取付フランジ５が嵌合され、かつ抜け出ないようにナツト６により締結される。取付フランジ５に駐車ブレーキの制動ドラム７の端壁と、渦電流減速装置の制動ドラム１３のボス部９と一体のフランジ部９ａとが重ね合され、複数のボルト１０とナツト１０ａにより締結される。
【０００８】
制動ドラム１３は鉄、アルミニウムなどの導体からなり、好ましくは、内周面１３ｃに、薄い銅板を筒形に成形してなる銅製筒体３５を結合される。制動ドラム１３は基端部を、ボス部９から放射方向へ延びる多数のスポーク１２に結合される。制動ドラム１３の外周壁に周方向等間隔に、多数の冷却フイン１３ａが一体に備えられる。
【０００９】
制動ドラム１３の内部に、断面箱形の内空部２３を有する案内筒１８が同軸に配設される。不動の案内筒１８は歯車箱２の突壁２ａに外嵌固定した枠板３１に、ボルト３２，３３により固定される。案内筒１８は外周壁部１８ａと内周壁部１８ｂとの両端に環状の端壁板を結合して構成してもよいが、図示の案内筒１８は普通の鉄などからなる左半部の断面コ字形をなす筒部分と、アルミニウムなどの非磁性体からなる右半部の断面逆Ｌ字形をなす筒部分とを、多数のボルト１４により結合して構成される。
【００１０】
制動ドラム１３の内周面１３ｃと対向する案内筒１８の外周壁部１８ａに、周方向等間隔に多数の開口が設けられ、各開口に強磁性板２１が嵌合固定される。実際には、強磁性板２１は外周壁部１８ａをアルミニウムから鋳造する際に鋳ぐるまれる。
【００１１】
補強リブ３１ａを有する枠板３１に、周方向等間隔に複数のアクチユエータ（図示せず）が支持される。アクチユエータはシリンダにピストンを嵌合して１対の流体圧室を区画し、ピストンから案内筒１８の内空部２３へ突出するロツド１７の端部に磁石支持筒１９を結合される。磁石支持筒１９は案内筒１８の内空部２３に軸方向移動可能に支持される。磁石支持筒１９の外周壁に、各強磁性板２１と対向する磁石２０が、極性が周方向に交互に異なるように結合される。
【００１２】
制動時、磁石支持筒１９は図１に示すように、アクチユエータのロツド１７により制動ドラム１３の内部へ突出される。回転する制動ドラム１３が磁石２０から強磁性板２１を経て制動ドラム１３の内周面１３ｃへ及ぶ磁界を横切る時、制動ドラム１３に渦電流が発生し、制動ドラム１３が制動トルクを発生する。制動ドラム１３は渦電流により発熱し、直接または冷却フイン１３ａを介して外気により冷却される。制動時、図２に示すように、磁石支持筒１９と制動ドラム１３との間に磁気回路４０が形成される。
【００１３】
非制動時、アクチユエータにより磁石支持筒１９を図１の左方へ移動し、制動ドラム１３から引退させれば、磁石２０は制動ドラム１３へ磁界を及ぼさなくなり、制動ドラム１３は制動トルクを発生しない。
【００１４】
本発明は強磁性板２１が案内筒１８から脱落するのを防止するために、厚板を単純に円弧状に湾曲して強磁性板とするものではなく、図３に代表されるように、型合せ面５６の外半部５１と内半部６１とをそれぞれ頭截角錐状に形成し、各角錐の底面を互いに重合せ結合したような立体形状にするものである。詳しくは、型鍛造または鋳造される強磁性板２１の断面形状について、型合せ面５６から制動ドラム１３と対向する外面へ近づくにつれて周方向の寸法が短くなるように、強磁性板２１の周方向端部の壁面を傾斜させてある。これにより、磁石２０から制動ドラム１３への磁束が集中し、磁束密度の低下が抑えられる。しかし、強磁性板２１の周方向端部の壁面の型合せ面５６に対する傾斜角（勾配）が小さすぎると、磁束が飽和してしまう。実験の結果によれば、強磁性板２１の周方向端部の壁面の傾斜角は約７５°が最適である。
【００１５】
図３，４に示す実施例では、型鍛造される強磁性板２１の円弧状に湾曲した型合せ面５６の外半部５１、すなわち制動ドラム１３に対向する外面５１ｂを有する外半部５１の側面断面が台形に形成され、磁石２０に対向する内面６１ｂを有する内半部６１の側面断面が台形に形成される。外半部５１と内半部６１との接続部、すなわち型合せ面５６に突条（ビード）５０が強磁性板２１の全周を囲むように形成される。換言すれば、強磁性板２１の外半部５１は周方向端部の壁面５１ａ，５１ｃを、型合せ面５６から外面５１ｂへ近づくにつれて周方向寸法が次第に短くなるように傾斜される。強磁性板２１の内半部６１も型鍛造の都合から、周方向端部の壁面６１ａ，６１ｃを型合せ面５６から内面６１ｂへ近づくにつれて周方向寸法が次第に短くなるように僅かに傾斜される。
【００１６】
図４に示すように、強磁性板２１の外半部５１の軸方向端部の壁面５１ｄは、型合せ面５６から外面５１ｂへ近づくにつれて軸方向寸法が次第に短くなるように傾斜される。強磁性板２１の内半部６１の軸方向端部の壁面６１ｄも、型合せ面５６から内面６１ｂへ近づくにつれて軸方向寸法が次第に短くなるように僅かに傾斜される。
【００１７】
上述の実施例において、突条（ビード）５０は周方向端部の壁面５１ａ，５１ｃ，６１ａ，６１ｃと軸方向端部の壁面５１ｄ，６１ｄのいずれか一方に設けるだけでもよい。また、強磁性板２１の周方向端部の壁面５１ａ，５１ｃと壁面６１ａ，６１ｃが傾斜されていれば、図５に示すように、強磁性板２１の軸方向端部の壁面５１ｄと壁面６１ｄとが同一平面をなすように、つまり強磁性板２１の正面断面がほぼ長方形をなすように構成してもよい。
【００１８】
図６に示す実施例では、強磁性板２１の側面断面の形状について、外半部５１の周方向端部の壁面５１ａ，５１ｃを単純な傾斜面でなく、型合せ面５６から外面５１ｂへ円弧状に絞つた曲面にして、磁石２０から制動ドラム１３へ向う磁束を絞り込むようにしたものであり、強磁性板２１の正面断面の形状については、図３，５に示すものと同様に構成することができる。
【００１９】
図７〜１０に示す実施例は、型合せ面５６に沿つて突条（ビード）を設けないものである。図７，８に示す実施例では、強磁性板２１の側面断面について、外半部５１の周方向端部の壁面５１ａ，５１ｃが、型合せ面５６から外面５１ｂへ近づくにつれて周方向寸法が次第に短くなるように傾斜される。強磁性板２１の内半部６１の周方向端部の壁面６１ａ，６１ｃは、型合せ面５６から内面６１ｂへ近づくにつれて周方向寸法が次第に短くなるように傾斜される。図８に示すように、強磁性板２１の正面断面については、外半部５１の軸方向端部の壁面５１ｄが、型合せ面５６から外面５１ｂへ近づくにつれて軸方向寸法が次第に短くなるように傾斜される。強磁性板２１の内半部６１の軸方向端部の壁面６１ｄは、型合せ面５６から内面６１ｂへ近づくにつれて軸方向寸法が次第に短くなるように傾斜される。
【００２０】
上述した各実施例では、強磁性板２１の正面断面が左右対称に構成されるが、図９に示すように、制動中の磁束の流れ（磁気回路のループ形状）を考慮して、外半部５１の軸方向端部の一方の壁面５１ｄの傾斜を緩やかに（型合せ面５６に対する傾斜角を小さく）するとか、図１０に示すように、外半部５１の軸方向端部の一方の壁面５１ｄの傾斜角と、内半部６１の軸方向端部の他方の壁面６１ｄの傾斜角とを小さくしてもよい。
【００２１】
本発明は上述のように、強磁性板２１の外面５１ｂと内面６１ｂの面積が、型合せ面５０の面積よりも狭くなつているので、案内筒１８の外周壁１８ａに鋳込まれた強磁性板２１が、磁石２０の吸引力を受けても、くさび効果により案内筒１８からの脱落を防止できる。
【００２２】
上述の実施例は、制動ドラムに対し磁石支持筒を軸方向に往復移動させて、磁石が強磁性板と対向する制動位置と、磁石が強磁性板と対向しない非制動位置とに切り換える形式の渦電流減速装置について説明したが、本発明はこれに限定されるものではなく、特開平4-88867号公報に開示されるような制動ドラムに対し１つの磁石支持筒を回動させて、極性が同じ２つの磁石が共通の強磁性板に対向する制動位置と、極性が異なる２つの磁石が共通の強磁性板に対向する非制動位置とに切り換える形式の渦電流減速装置や、特開平4-12659 号公報に開示されるような制動ドラムの内部に不動の磁石支持筒と可動の磁石支持筒を配設し、一方の磁石支持筒を回動させて、両方の磁石支持筒の極性が同じ磁石が共通の強磁性板と全面的に対向する制動位置と、両方の磁石支持筒の極性が異なる１対の磁石が共通の強磁性板と全面的に対向する非制動位置とに切り換える形式の渦電流減速装置にも適用できる。
【００２３】
【発明の効果】
本発明は上述のように、回転軸に結合した導体からなる制動ドラムの内部に、非磁性体からなりかつ断面長方形の内空部を有する不動の案内筒を同軸に配設し、前記案内筒の制動ドラムと対向する外周壁部に周方向等間隔に多数の強磁性板を結合し、前記案内筒の前記内空部に軸方向移動可能または回動可能に支持した少くとも１つの磁石支持筒に、前記強磁性板に対する極性が周方向に交互に異なるよう永久磁石を結合し、前記永久磁石が前記強磁性板と全面的に対向する制動位置と前記永久磁石が前記強磁性板と全面的には対向しない非制動位置とに前記磁石支持筒を移動させるアクチユエータを備えてなる永久磁石式渦電流減速装置において、型鍛造される前記強磁性板は型合せ面から制動ドラムに対向する外面に至る周方向端部の壁面を、型合せ面から前記外面へ近づくにつれて周方向の寸法が次第に短くなるように傾斜させ、型合せ面から磁石に対向する内面に至る周方向端部の壁面を、型合せ面から前記内面へ近づくにつれて周方向の寸法が次第に短くなるように傾斜させ、型合せ面の周縁部の少くとも一部に前記強磁性板の内方への抜けを阻止する突条からなる抜止め壁を備えたから、強磁性板が磁石に吸引力により案内筒から脱落するのを防止できる。
【図面の簡単な説明】
【図１】本発明が適用される渦電流減速装置の正面断面図である。
【図２】同渦電流減速装置の側面断面図である。
【図３】同渦電流減速装置における強磁性板の側面図である。
【図４】同強磁性板の正面図である。
【図５】同渦電流減速装置における強磁性板の他の実施例を示す正面断面図である。
【図６】同渦電流減速装置における強磁性板の他の実施例を示す側面断面図である。
【図７】同渦電流減速装置における強磁性板の他の実施例を示す側面図である。
【図８】同強磁性板の正面図である。
【図９】同渦電流減速装置における強磁性板の他の実施例を示す正面図である。
【図１０】同渦電流減速装置における強磁性板の他の実施例を示す正面図である。
【符号の説明】
４：回転軸５：取付フランジ５ａ：スプライン孔７：制動ドラム９：ボス部９ａ：フランジ部１２：スポーク１３：制動ドラム１３ａ：冷却フイン１３ｃ：内周面１８：案内筒１８ａ：外周壁部１８ｂ：内周壁部１９：磁石支持筒２０：磁石２１：強磁性板２３：内空部５０：抜止め突条５１：外半部５１ａ：壁面５１ｂ：外面５１ｃ：壁面５１ｄ：壁面５６：型合せ面６１：内半部６１ａ：壁面６１ｂ：内面６１ｃ：壁面６１ｄ：壁面[0001]
BACKGROUND OF THE INVENTION
The present invention mainly relates to an eddy current reduction device for assisting a friction brake of a large vehicle, and more particularly to a permanent magnet type eddy current reduction device in which a ferromagnetic plate is prevented from dropping off from a guide tube.
[0002]
[Prior art]
According to the permanent magnet type eddy current reduction device disclosed in Japanese Patent Application No. 8-293,354 filed by the present applicant, the cross-sectional shape of a substantially rectangular ferromagnetic plate (pole piece) is formed on the outer surface facing the braking drum. By making the trapezoid shorter than the inner surface, the braking force can be improved. In the above-described eddy current reduction device, a magnet support cylinder that supports a permanent magnet (hereinafter simply referred to as a magnet) is sealed inside a guide cylinder having an inner space with a rectangular cross section. A ferromagnetic plate that can face the magnet is cast into the outer peripheral wall portion of the guide tube, or the ferromagnetic plate is welded to the outer peripheral wall portion of the guide tube made of austenitic stainless steel. Switching between braking and non-braking can be achieved by moving the magnet support tube in the axial direction or circumferential direction. By making the cross-sectional shape of the ferromagnetic plate trapezoidal, the magnetic flux from the magnet to the braking drum rotating through the ferromagnetic plate is narrowed to increase the magnetic flux density, and the amount of eddy current generated in the braking drum is increased to increase the braking force. To increase.
[0003]
However, if the area of the ferromagnetic plate has a trapezoidal cross section extending toward the magnet, it is difficult to cast the ferromagnetic plate into the guide tube, and the ferromagnetic plate is attracted to the magnet during braking when the inner surface of the ferromagnetic plate overlaps the magnet. May come out of the guide tube. Also, the ferromagnetic plate can easily come off the guide tube when the brake drum is removed for repair inspection.
[0004]
[Problems to be solved by the invention]
In view of the above-described problems, an object of the present invention is to provide a permanent magnet type eddy current reduction device in which a ferromagnetic plate is not dropped from a guide tube.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, the configuration of the present invention is such that a non-moving guide cylinder made of a nonmagnetic material and having an inner space with a rectangular cross section is coaxially arranged inside a brake drum made of a conductor coupled to a rotating shaft. less then, combines a number of ferromagnetic plates in the circumferential direction at equal intervals on the outer peripheral wall portion facing the brake drum of said guide cylinder, and supported so as to be axially movable or rotating within said hollow portion of said guide tube In both cases, a permanent magnet is coupled to one magnet support cylinder so that the polarities with respect to the ferromagnetic plate are alternately different in the circumferential direction, the braking position where the permanent magnet completely faces the ferromagnetic plate, and the permanent magnet In a permanent magnet type eddy current reduction device including an actuator for moving the magnet support cylinder to a non-braking position that is not entirely opposed to the ferromagnetic plate, the ferromagnetic plate to be die forged is braked from the die mating surface. On the outer surface facing the drum That the wall surface of the circumferential end portion, is inclined from the mold face such circumferential dimension gradually becomes shorter as approaching to the outer surface, a wall surface of the circumferential ends extending on an inner surface facing the mold face to the magnet, From the protrusions that incline so that the circumferential dimension gradually decreases as approaching the inner surface from the mold matching surface, and prevent the ferromagnetic plate from slipping inward at least at a part of the peripheral edge of the mold matching surface . A retaining wall is provided.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the ferromagnetic plate is provided with a retaining wall so that the ferromagnetic plate (pole piece) does not come out of the guide tube due to the attractive force of the magnet. The ferromagnetic plate has an intermediate thickness, that is, a section outside the mold matching surface (parting line), that is, a cross section of the outer half, and the inner half of the mold matching surface is substantially rectangular as in the prior art. In other words, the wall surface at the circumferential end or the axial end of the outer half of the mold matching surface of the ferromagnetic plate is inclined. Further, protrusions (leads) are provided on the ferromagnetic plate along the mold matching surface so that the ferromagnetic plate does not come off the guide tube due to the attractive force of the magnet. Here, the die mating surface refers to a boundary surface between an upper die and a lower die used for forging or casting of a ferromagnetic plate.
[0007]
【Example】
FIG. 1 is a front sectional view of an eddy current reduction device to which the present invention is applied, and FIG. 2 is a side sectional view thereof. The eddy current reduction device has a braking drum 13 coupled to the rotating shaft 4. For this reason, a mounting flange 5 having a spline hole 5a is fitted to the output rotary shaft 4 supported by the bearing 3 on the end wall of the gear box 2 of the transmission and protruding from the end wall, and the nut 6 is prevented from coming out. It is concluded by. The end wall of the braking drum 7 of the parking brake and the boss 9 of the braking drum 13 of the eddy current speed reducing device 9 are integrated with the mounting flange 5 and are fastened by a plurality of bolts 10 and nuts 10a. .
[0008]
The brake drum 13 is made of a conductor such as iron or aluminum. Preferably, a copper cylinder 35 formed by forming a thin copper plate into a cylindrical shape is coupled to the inner peripheral surface 13c. The brake drum 13 is coupled at its proximal end to a number of spokes 12 extending radially from the boss portion 9. A number of cooling fins 13 a are integrally provided on the outer peripheral wall of the brake drum 13 at equal intervals in the circumferential direction.
[0009]
Inside the brake drum 13, a guide cylinder 18 having an inner space 23 having a box-shaped cross section is disposed coaxially. The stationary guide cylinder 18 is fixed by bolts 32 and 33 to a frame plate 31 that is externally fixed to the protruding wall 2a of the gear box 2. The guide tube 18 may be configured by connecting annular end wall plates to both ends of the outer peripheral wall portion 18a and the inner peripheral wall portion 18b. However, the illustrated guide tube 18 has a left half section made of ordinary iron or the like. A cylindrical portion having a U-shape and a cylindrical portion having an inverted L-shaped cross section in the right half made of a non-magnetic material such as aluminum are connected by a large number of bolts 14.
[0010]
A number of openings are provided at equal intervals in the circumferential direction on the outer peripheral wall portion 18a of the guide cylinder 18 facing the inner peripheral surface 13c of the brake drum 13, and the ferromagnetic plate 21 is fitted and fixed to each opening. Actually, the ferromagnetic plate 21 is cast when the outer peripheral wall portion 18a is cast from aluminum.
[0011]
A plurality of actuators (not shown) are supported on the frame plate 31 having the reinforcing ribs 31a at equal intervals in the circumferential direction. The actuator has a piston fitted into the cylinder to define a pair of fluid pressure chambers, and a magnet support cylinder 19 is coupled to the end of the rod 17 projecting from the piston to the inner space 23 of the guide cylinder 18. The magnet support cylinder 19 is supported by the inner space 23 of the guide cylinder 18 so as to be movable in the axial direction. Magnets 20 facing the respective ferromagnetic plates 21 are coupled to the outer peripheral wall of the magnet support cylinder 19 so that the polarities are alternately different in the circumferential direction.
[0012]
At the time of braking, the magnet support cylinder 19 is protruded into the brake drum 13 by the rod 17 of the actuator as shown in FIG. When the rotating brake drum 13 crosses the magnetic field extending from the magnet 20 through the ferromagnetic plate 21 to the inner peripheral surface 13c of the brake drum 13, an eddy current is generated in the brake drum 13, and the brake drum 13 generates a braking torque. The brake drum 13 generates heat due to an eddy current and is cooled by the outside air directly or via the cooling fin 13a. During braking, a magnetic circuit 40 is formed between the magnet support cylinder 19 and the braking drum 13 as shown in FIG.
[0013]
When the brake is not braked, if the magnet support cylinder 19 is moved to the left in FIG. .
[0014]
In the present invention, in order to prevent the ferromagnetic plate 21 from falling off the guide tube 18, the thick plate is not simply bent into an arc shape to form a ferromagnetic plate, but as represented by FIG. The outer half 51 and the inner half 61 of the mold matching surface 56 are each formed into a truncated cone shape, and the bottom surfaces of the respective pyramids are superposed on each other to form a solid shape. Specifically, with respect to the cross-sectional shape of the ferromagnetic plate 21 to be die forged or cast, the circumferential direction of the ferromagnetic plate 21 is such that the dimension in the circumferential direction becomes shorter from the die matching surface 56 toward the outer surface facing the braking drum 13. The wall surface of the end is inclined. Thereby, the magnetic flux from the magnet 20 to the braking drum 13 concentrates, and the fall of magnetic flux density is suppressed. However, if the inclination angle (gradient) of the wall surface at the circumferential end of the ferromagnetic plate 21 with respect to the mold matching surface 56 is too small, the magnetic flux is saturated. According to the results of the experiment, the inclination angle of the wall surface at the circumferential end of the ferromagnetic plate 21 is optimally about 75 °.
[0015]
In the embodiment shown in FIGS. 3 and 4, the outer half 51 of the die-matching surface 56 curved in the arc shape of the ferromagnetic plate 21 to be die-forged, that is, the outer half 51 having the outer surface 51 b facing the brake drum 13. A side cross-section is formed in a trapezoidal shape, and a side cross-section of the inner half 61 having an inner surface 61b facing the magnet 20 is formed in a trapezoid. A protrusion (bead) 50 is formed on the connecting portion between the outer half 51 and the inner half 61, that is, on the mold matching surface 56 so as to surround the entire circumference of the ferromagnetic plate 21. In other words, the outer half 51 of the ferromagnetic plate 21 is inclined so that the circumferential dimension gradually decreases as the wall surfaces 51a and 51c at the circumferential ends approach the outer surface 51b from the die-matching surface 56. For the convenience of die forging, the inner half 61 of the ferromagnetic plate 21 is also slightly inclined so that the circumferential dimension gradually decreases as the wall surfaces 61a and 61c at the circumferential ends approach the inner surface 61b from the die mating surface 56. .
[0016]
As shown in FIG. 4, the wall surface 51 d at the axial end of the outer half 51 of the ferromagnetic plate 21 is inclined so that the axial dimension gradually decreases as it approaches the outer surface 51 b from the mold matching surface 56. The wall surface 61d at the axial end of the inner half 61 of the ferromagnetic plate 21 is also slightly inclined so that the axial dimension gradually decreases as the mold matching surface 56 approaches the inner surface 61b.
[0017]
In the embodiment described above, the ridges (beads) 50 may be provided only on one of the wall surfaces 51a, 51c, 61a, 61c at the circumferential end and the wall surfaces 51d, 61d at the axial end. If the wall surfaces 51a and 51c and the wall surfaces 61a and 61c at the circumferential end of the ferromagnetic plate 21 are inclined, as shown in FIG. 5, the wall surface 51d and the wall surface 61d at the axial end of the ferromagnetic plate 21 are provided. And the ferromagnetic plate 21 may have a substantially rectangular front cross section.
[0018]
In the embodiment shown in FIG. 6, with respect to the shape of the side cross-section of the ferromagnetic plate 21, the wall surfaces 51a and 51c at the circumferential end of the outer half 51 are not simply inclined surfaces but are circular from the mold matching surface 56 to the outer surface 51b. An arc-shaped curved surface is used to narrow the magnetic flux from the magnet 20 to the braking drum 13, and the front cross-sectional shape of the ferromagnetic plate 21 is configured in the same manner as shown in FIGS. be able to.
[0019]
In the embodiment shown in FIGS. 7 to 10, no protrusions (beads) are provided along the mold matching surface 56. In the embodiment shown in FIGS. 7 and 8, with respect to the side cross-section of the ferromagnetic plate 21, the circumferential dimension gradually increases as the wall surfaces 51 a and 51 c at the circumferential end of the outer half 51 approach the outer surface 51 b from the mold matching surface 56. Inclined to be shorter. The wall surfaces 61a and 61c at the circumferential end of the inner half 61 of the ferromagnetic plate 21 are inclined so that the circumferential dimension gradually decreases as the die matching surface 56 approaches the inner surface 61b. As shown in FIG. 8, with respect to the front cross section of the ferromagnetic plate 21, the axial dimension gradually decreases as the wall surface 51 d at the axial end portion of the outer half 51 approaches the outer surface 51 b from the mold-matching surface 56. Be inclined. The wall surface 61d at the axial end of the inner half 61 of the ferromagnetic plate 21 is inclined such that the axial dimension gradually decreases as the mold matching surface 56 approaches the inner surface 61b.
[0020]
In each of the above-described embodiments, the front cross section of the ferromagnetic plate 21 is configured to be bilaterally symmetric, but as shown in FIG. 9, the outer half is taken into account in consideration of the flow of magnetic flux during braking (loop shape of the magnetic circuit). The inclination of one wall surface 51d at the axial end of the portion 51 is made gentle (the inclination angle with respect to the mold-matching surface 56 is made small), or as shown in FIG. The inclination angle of the wall surface 51d and the inclination angle of the other wall surface 61d at the axial end of the inner half portion 61 may be reduced.
[0021]
In the present invention, as described above, the area of the outer surface 51b and the inner surface 61b of the ferromagnetic plate 21 is narrower than the area of the die-matching surface 50, so that the ferromagnetic material cast into the outer peripheral wall 18a of the guide tube 18 is used. Even if the plate 21 receives the attractive force of the magnet 20, it can be prevented from falling off the guide tube 18 due to the wedge effect.
[0022]
In the above-described embodiment, the magnet support cylinder is reciprocated in the axial direction with respect to the brake drum to switch between a braking position where the magnet faces the ferromagnetic plate and a non-braking position where the magnet does not face the ferromagnetic plate. Although the eddy current reduction device has been described, the present invention is not limited to this, and one pole is rotated by rotating one magnet support cylinder with respect to a brake drum as disclosed in JP-A-4-88867. An eddy current reduction device that switches between a braking position where two magnets having the same property face a common ferromagnetic plate and a non-braking position where two magnets having different polarities face a common ferromagnetic plate; A stationary magnet support cylinder and a movable magnet support cylinder are arranged inside a brake drum as disclosed in Japanese Patent No. 4-12659, and one of the magnet support cylinders is rotated so that the polarities of both magnet support cylinders Braking position where the same magnet is completely opposite the common ferromagnetic plate The present invention can also be applied to an eddy current reduction device of a type in which a pair of magnets having different polarities of both the magnet support cylinders are switched to a non-braking position facing the common ferromagnetic plate entirely.
[0023]
【The invention's effect】
As described above, in the present invention, a stationary guide cylinder made of a nonmagnetic material and having an inner space with a rectangular cross section is coaxially disposed inside a brake drum made of a conductor coupled to a rotating shaft, and the guide cylinder At least one magnet support in which a large number of ferromagnetic plates are coupled to the outer peripheral wall portion facing the brake drum at equal intervals in the circumferential direction and supported in the inner space of the guide tube so as to be axially movable or rotatable. Permanent magnets are coupled to the cylinder so that the polarities with respect to the ferromagnetic plates are alternately different in the circumferential direction, the braking position where the permanent magnets are completely opposed to the ferromagnetic plates, and the permanent magnets are entirely opposed to the ferromagnetic plates. In the permanent magnet type eddy current speed reducer comprising an actuator for moving the magnet support cylinder to a non-braking position that is not opposed to each other, the die plate forged ferromagnetic plate is an outer surface facing the braking drum from the die-matching surface The wall at the end in the circumferential direction And is inclined from the mold face such circumferential dimension gradually becomes shorter as approaching to the outer surface, the mold face the wall surface of the circumferential ends extending on an inner surface facing the magnet, from the mold face to the inner face Since it is inclined so that the dimension in the circumferential direction becomes gradually shorter as it approaches, at least a part of the peripheral edge of the die-matching surface is provided with a retaining wall made of a protrusion that prevents the ferromagnetic plate from coming out inward. The ferromagnetic plate can be prevented from falling off the guide tube due to the attractive force of the magnet.
[Brief description of the drawings]
FIG. 1 is a front sectional view of an eddy current reduction device to which the present invention is applied.
FIG. 2 is a side sectional view of the eddy current reduction device.
FIG. 3 is a side view of a ferromagnetic plate in the eddy current reduction device.
FIG. 4 is a front view of the ferromagnetic plate.
FIG. 5 is a front sectional view showing another embodiment of the ferromagnetic plate in the eddy current reduction device.
FIG. 6 is a side sectional view showing another embodiment of the ferromagnetic plate in the eddy current reduction device.
FIG. 7 is a side view showing another embodiment of a ferromagnetic plate in the eddy current reduction device.
FIG. 8 is a front view of the ferromagnetic plate.
FIG. 9 is a front view showing another embodiment of the ferromagnetic plate in the eddy current reduction device.
FIG. 10 is a front view showing another embodiment of the ferromagnetic plate in the eddy current reduction device.
[Explanation of symbols]
4: rotating shaft 5: mounting flange 5a: spline hole 7: braking drum 9: boss portion 9a: flange portion 12: spoke 13: braking drum 13a: cooling fin 13c: inner peripheral surface 18: guide tube 18a: outer peripheral wall portion 18b : Inner peripheral wall part 19: Magnet support cylinder 20: Magnet 21: Ferromagnetic plate 23: Inner cavity part 50: Detaching protrusion 51: Outer half part 51a: Wall surface 51b: Outer surface 51c: Wall surface 51d: Wall surface 56: Mold matching surface 61: Inner half 61a: Wall surface 61b: Inner surface 61c: Wall surface 61d: Wall surface

Claims

回転軸に結合した導体からなる制動ドラムの内部に、非磁性体からなりかつ断面長方形の内空部を有する不動の案内筒を同軸に配設し、前記案内筒の制動ドラムと対向する外周壁部に周方向等間隔に多数の強磁性板を結合し、前記案内筒の前記内空部に軸方向移動可能または回動可能に支持した少くとも１つの磁石支持筒に、前記強磁性板に対する極性が周方向に交互に異なるよう永久磁石を結合し、前記永久磁石が前記強磁性板と全面的に対向する制動位置と前記永久磁石が前記強磁性板と全面的には対向しない非制動位置とに前記磁石支持筒を移動させるアクチユエータを備えてなる永久磁石式渦電流減速装置において、型鍛造される前記強磁性板は型合せ面から制動ドラムに対向する外面に至る周方向端部の壁面を、型合せ面から前記外面へ近づくにつれて周方向の寸法が次第に短くなるように傾斜させ、型合せ面から磁石に対向する内面に至る周方向端部の壁面を、型合せ面から前記内面へ近づくにつれて周方向の寸法が次第に短くなるように傾斜させ、型合せ面の周縁部の少くとも一部に前記強磁性板の内方への抜けを阻止する突条からなる抜止め壁を備えたことを特徴とする、永久磁石式渦電流減速装置。A stationary guide cylinder made of a non-magnetic material and having an inner space with a rectangular cross section is coaxially arranged inside a brake drum made of a conductor coupled to a rotating shaft, and an outer peripheral wall facing the brake drum of the guide cylinder A large number of ferromagnetic plates are coupled to the part at equal intervals in the circumferential direction, and at least one magnet support cylinder supported in the inner space of the guide cylinder so as to be axially movable or pivotable is attached to the ferromagnetic plate. Permanent magnets are coupled so that the polarities are alternately different in the circumferential direction, and the braking position where the permanent magnet is completely opposed to the ferromagnetic plate and the non-braking position where the permanent magnet is not completely opposed to the ferromagnetic plate In the permanent magnet type eddy current reduction device comprising an actuator for moving the magnet support cylinder, the ferromagnetic plate to be die forged is a wall surface at a circumferential end extending from the die matching surface to the outer surface facing the brake drum From the mating surface Closer to the surface is inclined so that the circumferential dimension is gradually reduced, the wall surface of the circumferential ends extending on an inner surface facing the mold face to the magnet, the circumferential dimension as the mold face closer to the inner surface The permanent wall is characterized by being provided with a retaining wall made of a ridge which is inclined so as to be gradually shortened and which prevents at least a part of the peripheral edge portion of the die-matching surface from slipping out of the ferromagnetic plate. Magnet type eddy current reduction device.