JP3690471B2

JP3690471B2 - Eddy current reducer

Info

Publication number: JP3690471B2
Application number: JP26827298A
Authority: JP
Inventors: 徹桑原
Original assignee: Isuzu Motors Ltd
Current assignee: Isuzu Motors Ltd
Priority date: 1998-09-22
Filing date: 1998-09-22
Publication date: 2005-08-31
Anticipated expiration: 2018-09-22
Also published as: JP2000102240A

Description

【０００１】
【発明の属する技術分野】
本発明は大形車両などの摩擦ブレーキの負担を軽減する渦電流減速装置、特に永久磁石（以下、これを単に磁石という）の磁束が制動ドラムへ有効に働くようにした渦電流減速装置に関するものである。
【０００２】
【従来の技術】
特開平4-88867 号公報に開示される渦電流減速装置では、図２に示すように、例えば車両用変速機の出力回転軸１に結合される導体からなる制動ドラム７と、制動ドラム７の内部に配設される非磁性体からなる案内筒１０と、案内筒１０の内空部に回動可能に支持した磁性体からなる磁石支持筒１４とを備えている。制動ドラム７はボス５のフランジ部５ａを、駐車ブレーキの制動ドラム３の端壁部と一緒に、回転軸１にスプライン嵌合固定した取付フランジ２に重ね合され、かつボルト４により締結される。ボス５から放射状に延びるスポーク６に、放熱フイン８を備えた制動ドラム７が結合される。
【０００３】
案内筒１０は断面長方形の内空部を備えており、具体的には断面コ字形をなす筒体に、環状の蓋板１１を結合して構成される。案内筒１０は適当な手段により例えば変速機の歯車箱に固定される。案内筒１０の外筒部１０ａに周方向等間隔に設けた多数の開口１３に、強磁性板（ポールピース）１５がそれぞれ結合される。好ましくは、強磁性板１５は案内筒１０の成形時鋳ぐるまれる。磁石支持筒１４は案内筒１０の内空部、詳しくは内筒部１０ｂに軸受１２により回動可能に支持される。
【０００４】
案内筒１０の左端壁に、好ましくは３つの流体圧アクチユエータ２０が周方向等間隔に結合される。流体圧アクチユエータ２０はシリンダ１８にピストン１７を嵌装してなり、ピストン１７から外部へ突出するロツドに、磁石支持筒１４から案内筒１０の左端壁のスリツトを経て突出する腕１６が連結される。磁石支持筒１４に強磁性板１５の約半分の面積で倍数の磁石１４ａが、強磁性板１５の配列ピツチの１／２の配列ピツチで周方向等間隔に結合される。図３に示すように、磁石支持筒１４はアルミニウムなどの非磁性体からなり、多数の磁石１４ａが、強磁性板１５と対向しかつ強磁性板１５に対する極性が周方向に２つずつ異なるように配設される。
【０００５】
図３に示すように、非制動時、共通の強磁性板１５に対し、周方向に隣接する２つの磁石１４ａの極性が互いに異なる状態では、強磁性板１５と磁石支持筒１４との間に短絡的磁気回路ｙが生じ、制動ドラム７に磁界を及ぼさない。
【０００６】
図４に示すように、制動時、流体圧アクチユエータ２０により磁石支持筒１４を磁石１４ａの配列ピツチｐだけ回動すると、共通の強磁性板１５に対し、隣接する２つの磁石１４ａの極性が同じになる。したがつて、２つの磁石１４ａが等しく強磁性板１５を経て制動ドラム７に磁界を及ぼす。回転する制動ドラム７が磁界を横切る時、制動ドラム７に渦電流が流れ、制動ドラム７が制動トルクを受ける。この時、制動ドラム７と磁石支持筒１４との間に磁気回路ｚが生じる。
【０００７】
上述したように、磁石支持筒１４の外周面に多数の磁石１４ａを、強磁性板１５に対向する極性がＮ，Ｎ，Ｓ，Ｓ，…というように、２つごとに異なるように結合し、２つの磁石１４ａの外面を覆うように強磁性板１５（強磁性材かつ軟磁性材からなる）を案内筒１０に配置し、流体圧アクチエータ２０により磁石１４ａの配列ピツチｐだけ磁石支持筒１４を正逆回動させて、制動位置と非制動位置との切換えを行う従来の渦電流減速装置では、強磁性板１５の断面形状、正確には案内筒１０の中心軸線に対して垂直な断面の形状が、ほぼ長方形をなしていたので、磁石支持筒１４の磁石１４ａから制動ドラム７へ向う磁束の集中が得られず、制動力の低下を招いていた。つまり、上述の渦電流減速装置では、磁石１４ａの外面の面積よりも強磁性板１５の外面の面積のほうが広く、強磁性板１５から出てくる磁束密度が小さくなり、制動力の低下を招いていたのである。
【０００８】
【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、強磁性板の回転軸に対する断面形状を台形に似た形にし、磁束密度を高めて制動力を向上させる渦電流減速装置を提供することにある。
【０００９】
【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制動ドラムの内部に、非磁性体からなる断面長方形の内空部を有する案内筒を配設し、該案内筒の外筒部に周方向等間隔に多数の強磁性板を配設し、案内筒の内部に軸方向移動可能または回動可能に配設した磁性体からなる少くとも１つの磁石支持筒の外周面に、強磁性板に対する極性が周方向に交互に異なるように磁石を結合し、同極性の磁石が各強磁性板に全面的に対向する制動位置と、磁石が各強磁性板に全面的には対向しない非制動位置とに切り換わる渦電流減速装置において、前記強磁性板の磁石に対向する内面に隣接する前後の壁面を内面に対し垂直な第１の壁面とし、前記強磁性板の制動ドラムに対向する外面に隣接する前後の壁面を外面に対し垂直な第２の壁面とし、第１の壁面と第２の壁面との間の前後の壁面を、前後の壁面の周方向の間隔が内面から外面へ向かつて次第に狭くなるように互いに反対方向へ傾斜させたことを特徴とする。
【００１０】
【発明の実施の形態】
強磁性板の周方向寸法を径外方へ向かつて狭めて台形に似た形にし、磁束密度を高めて制動力を向上させる。特に、強磁性板が２つの磁石と磁石の間を覆う部分の肉厚を最大にする。これにより、強磁性板の外面の面積が狭くなり、磁石から強磁性板を経て制動ドラムへ向う磁束密度が高められる。
【００１１】
【実施例】
図１に示すように、本発明は強磁性板１５の制動ドラム７に対する磁束密度を高めるために、強磁性板１５の回転軸（制動ドラム７の中心軸線）に垂直な断面形状を、内面２５から外面２４に向けて周方向寸法W2が周方向寸法W1へと次第に小さくなるように、ほぼ台形に構成したものである。したがつて、強磁性板１５の外面２４は内面２５よりも狭くなる。制動ドラム７の矢印ｘ方向の回転に関して、強磁性板１５の前方の壁面は壁面２６ａ，２６，２７からなり、強磁性板１５の後方の壁面は壁面２８ａ，２８，２９からなる。強磁性板１５の内面２５に隣接する壁面２７，２９は、強磁性板１５の体積を確保するために、制動ドラム７の回転中心から径外方へ延びる線と平行にされる。つまり、前方の壁面２６と後方の壁面２８は、２つの磁石１４ａの間を通る径方向線に関してほぼ対称に傾斜される。上述の形状に予め成形された磁石１４ａは、案内筒１０をアルミニウムから鋳造する際に、鋳型へ配列されて鋳込まれる。共通の強磁性板１５に対向する極性が同じ磁石は１つの連続したものとしてもよい。
【００１２】
案内筒１０の外筒部１０ａの壁面２６ａ，２８ａ，２６，２８と接する部分２１が鋭角になり、この部分２１から熱などの影響により破損する恐れがあるので、図１に示す実施例では、傾斜した壁面２６，２８の外面２４に隣接する部分を、案内筒１０の外周面に対しほぼ垂直な壁面２６ａ，２８ａに形成し、外面２４にほぼ垂直な壁面２６ａ，２８ａと内面２５にほぼ垂直な壁面２７，２９との間に、内面２５から外面２４へ向つて周方向寸法が次第に縮小するように互いに反対方向へ傾斜した壁面２６，２８が形成される。これにより、案内筒１０の外筒部１０ａと強磁性板１５との安定な結合が得られる。
【００１３】
本発明は図２に示す渦電流減速装置に限定されるものではなく、他の形式の渦電流減速装置にも適用できる。図５に示す実施例では、回転軸１に結合した制動ドラム７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案内筒１０を配設し、案内筒１０の外筒部１０ａに周方向等間隔に多数の強磁性板１５を配設し、案内筒１０の内部に配設した磁性体からなる可動の磁石支持筒１４と不動の磁石支持筒３４の外周面に、各強磁性板１５に対向しかつ強磁性板１５に対する極性が周方向に交互に異なるように磁石１４ａ，３４ａをそれぞれ結合し、同極性の磁石１４ａ，３４ａが各強磁性板１５に全面的に対向する制動位置と、異極性の磁石１４ａ，３４ａが各強磁性板１５に全面的に対向する図示の非制動位置とに、可動の磁石支持筒１４をアクチユエータ２０により正逆回動して切り換えられるものであり、図１に示したように、強磁性板１５の周方向の寸法は内面２５から外面２４へ向かつて次第に狭められる。
【００１４】
図６に示す実施例では、回転軸１に結合した制動ドラム７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案内筒１０を配設し、案内筒１０の外筒部１０ａに周方向等間隔に多数の強磁性板１５を配設し、案内筒１０の内部に軸方向移動可能に配設した磁性体からなる磁石支持筒１４の外面に、各強磁性板１５に対する極性が周方向に交互に異なるように磁石１４ａを結合し、磁石支持筒１０を制動ドラム７の内部へ突出させて各磁石１４ａが各強磁性板１５に全面的に対向する図示の制動位置と、磁石支持筒１４を制動ドラム７から軸方向に引退させて各磁石１４ａが各強磁性板１５に対向しない非制動位置とにアクチユエータ２０により切り換えられるものであり、図１に示したように、強磁性板１５の周方向の寸法は内面から外面へ向かつて次第に狭められる。
【００１５】
以上説明したように、本発明は強磁性板１５の回転軸に垂直な断面の形状を、内面２５よりも外面２４が狭くなつているほぼ台形にされているので、磁石１４ａから強磁性板１５を経て制動ドラム７へ及ぼす磁束が絞られる。つまり、２つの磁石１４ａの磁束が強磁性板１５を透過する時に絞られて制動ドラム７ヘ及ぶので、制動ドラム７の内部で磁束密度が大きくなり、制動ドラム７の内部に発生する渦電流が強くなり、制動力が高められる。
【００１６】
【発明の効果】
要するに、本発明は回転軸に結合した制動ドラムの内部に、非磁性体からなる断面長方形の内空部を有する案内筒を配設し、該案内筒の外筒部に周方向等間隔に多数の強磁性板を配設し、案内筒の内部に軸方向移動可能または回動可能に配設した磁性体からなる少くとも１つの磁石支持筒の外周面に、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に１つずつ磁石を結合し、同極性の磁石が各強磁性板に全面的に対向する制動位置と、磁石が各強磁性板に全面的には対向しない非制動位置とに切り換わる渦電流減速装置において、前記強磁性板の磁石に対向する内面に隣接する前後の壁面を内面に対し垂直な第１の壁面とし、前記強磁性板の制動ドラムに対向する外面に隣接する前後の壁面を外面に対し垂直な第２の壁面とし、第１の壁面と第２の壁面との間の前後の壁面を、前後の壁面の周方向の間隔が内面から外面へ向かつて次第に狭くなるように互いに反対方向へ傾斜させたものであり、磁石からの磁束が強磁性板を透過する時に絞られて制動ドラムヘ及ぶので、制動ドラムの内部での磁束密度が大きくなり、制動力が向上される。
【図面の簡単な説明】
【図１】本発明の実施例に係る渦電流減速装置の要部を示す正面断面図である。
【図２】本発明が適用される渦電流減速装置の上半部を示す側面断面図である。
【図３】同渦電流減速装置の非制動状態を示す正面断面図である。
【図４】同渦電流減速装置の制動状態を示す正面断面図である。
【図５】本発明が適用される他の渦電流減速装置の上半部を示す側面断面図である。
【図６】本発明が適用される他の渦電流減速装置の上半部を示す側面断面図である。
【符号の説明】
W1，W2：周方向寸法１：回転軸６：スポーク７：制動ドラム８：放熱フイン１０：案内筒１０ａ：外筒部１０ｂ：内筒部１４，３４：磁石支持筒１４ａ，３４ａ：磁石１５：強磁性板２０：流体圧アクチユエータ２４：外面２５：内面２６：側面２７：側面２８：側面２９：側面[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an eddy current reduction device for reducing the burden of a friction brake on a large vehicle or the like, and more particularly to an eddy current reduction device in which a magnetic flux of a permanent magnet (hereinafter simply referred to as a magnet) works effectively on a braking drum. It is.
[0002]
[Prior art]
In the eddy current reduction device disclosed in Japanese Patent Laid-Open No. 4-88867, as shown in FIG. 2, for example, a brake drum 7 made of a conductor coupled to an output rotation shaft 1 of a vehicle transmission, A guide tube 10 made of a non-magnetic material disposed inside and a magnet support tube 14 made of a magnetic material rotatably supported in the inner space of the guide tube 10 are provided. The brake drum 7 is overlapped with the flange 5a of the boss 5 together with the end wall of the brake drum 3 of the parking brake on the mounting flange 2 that is spline-fitted to the rotary shaft 1 and fastened by a bolt 4. . A brake drum 7 having a heat radiation fin 8 is coupled to the spokes 6 that extend radially from the boss 5.
[0003]
The guide cylinder 10 includes an inner space having a rectangular cross section, and specifically, is configured by connecting an annular cover plate 11 to a cylindrical body having a U-shaped cross section. The guide tube 10 is fixed to a gear box of a transmission, for example, by appropriate means. Ferromagnetic plates (pole pieces) 15 are coupled to a large number of openings 13 provided at equal intervals in the circumferential direction in the outer tube portion 10a of the guide tube 10 respectively. Preferably, the ferromagnetic plate 15 is cast when the guide tube 10 is formed. The magnet support cylinder 14 is rotatably supported by the bearing 12 on the inner space of the guide cylinder 10, more specifically, the inner cylinder 10b.
[0004]
Preferably, three fluid pressure actuators 20 are coupled to the left end wall of the guide tube 10 at equal intervals in the circumferential direction. The fluid pressure actuator 20 has a piston 17 fitted to a cylinder 18, and an arm 16 protruding from the magnet support cylinder 14 through a slit on the left end wall of the guide cylinder 10 is connected to a rod protruding outward from the piston 17. . The magnet support cylinder 14 is coupled with magnets 14a, which are approximately half the area of the ferromagnetic plate 15 and a multiple of the magnet plate 14a, at equal intervals in the circumferential direction by an arrangement pitch that is 1/2 of the arrangement pitch of the ferromagnetic plate 15. As shown in FIG. 3, the magnet support cylinder 14 is made of a nonmagnetic material such as aluminum, and a large number of magnets 14a face the ferromagnetic plate 15 so that the polarities with respect to the ferromagnetic plate 15 differ by two in the circumferential direction. It is arranged.
[0005]
As shown in FIG. 3, during non-braking, when the polarities of the two magnets 14a adjacent to each other in the circumferential direction are different from each other with respect to the common ferromagnetic plate 15, there is a gap between the ferromagnetic plate 15 and the magnet support cylinder 14. A short circuit magnetic circuit y is generated and no magnetic field is applied to the brake drum 7.
[0006]
As shown in FIG. 4, when braking, when the magnet support cylinder 14 is rotated by the arrangement pitch p of the magnets 14a by the fluid pressure actuator 20, the two adjacent magnets 14a have the same polarity with respect to the common ferromagnetic plate 15. become. Therefore, the two magnets 14 a equally apply a magnetic field to the braking drum 7 through the ferromagnetic plate 15. When the rotating brake drum 7 crosses the magnetic field, an eddy current flows through the brake drum 7 and the brake drum 7 receives a braking torque. At this time, a magnetic circuit z is generated between the brake drum 7 and the magnet support cylinder 14.
[0007]
As described above, a large number of magnets 14a are coupled to the outer peripheral surface of the magnet support cylinder 14 so that the polarities facing the ferromagnetic plate 15 are different from each other such as N, N, S, S,. A ferromagnetic plate 15 (made of a ferromagnetic material and a soft magnetic material) is disposed on the guide tube 10 so as to cover the outer surfaces of the two magnets 14a, and the magnet support tube 14 is arranged by the fluid pressure actuator 20 by an arrangement pitch p of the magnets 14a. In the conventional eddy current reduction device that switches between the braking position and the non-braking position by rotating the forward and reverse, the cross-sectional shape of the ferromagnetic plate 15, more precisely, the cross-section perpendicular to the central axis of the guide cylinder 10 Is substantially rectangular, the concentration of magnetic flux from the magnet 14a of the magnet support cylinder 14 toward the braking drum 7 cannot be obtained, leading to a reduction in braking force. That is, in the above-described eddy current reduction device, the area of the outer surface of the ferromagnetic plate 15 is larger than the area of the outer surface of the magnet 14a, and the magnetic flux density coming out of the ferromagnetic plate 15 is reduced, resulting in a decrease in braking force. It was.
[0008]
[Problems to be solved by the invention]
In view of the above-described problems, an object of the present invention is to provide an eddy current reduction device in which the cross-sectional shape of a ferromagnetic plate with respect to the rotation axis is similar to a trapezoid, and the magnetic flux density is increased to improve the braking force.
[0009]
[Means for Solving the Problems]
In order to solve the above problems, the configuration of the present invention is such that a guide cylinder having an inner space with a rectangular cross section made of a non-magnetic material is disposed inside a brake drum coupled to a rotating shaft, and the outer cylinder of the guide cylinder A large number of ferromagnetic plates are arranged at equal intervals in the circumferential direction on the outer peripheral surface of at least one magnet support cylinder made of a magnetic body that is axially movable or rotatable inside the guide cylinder. The magnets are coupled so that the polarities with respect to the ferromagnetic plates are alternately different in the circumferential direction, and the braking position where the magnets of the same polarity are opposed to the respective ferromagnetic plates and the magnets are opposed to the respective ferromagnetic plates. In the eddy current reduction device that switches to the non-braking position, the front and rear wall surfaces adjacent to the inner surface facing the magnet of the ferromagnetic plate are first wall surfaces perpendicular to the inner surface, and the braking drum of the ferromagnetic plate is The second wall surface perpendicular to the outer surface on the front and rear wall surfaces adjacent to the opposing outer surface And, characterized in that the front and rear walls, the circumferential spacing of the front and rear walls is inclined in mutually opposite directions such that countercurrent former gradually narrowed to the outer surface from the inner surface between the first and second walls And
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The circumferential dimension of the ferromagnetic plate is once narrowed outward in a radial shape to resemble a trapezoid, and the magnetic flux density is increased to improve the braking force. In particular, the thickness of the portion where the ferromagnetic plate covers between the two magnets is maximized. Thereby, the area of the outer surface of the ferromagnetic plate is reduced, and the magnetic flux density from the magnet to the braking drum through the ferromagnetic plate is increased.
[0011]
【Example】
As shown in FIG. 1, in the present invention, in order to increase the magnetic flux density of the ferromagnetic plate 15 with respect to the braking drum 7, a cross-sectional shape perpendicular to the rotation axis of the ferromagnetic plate 15 (center axis of the braking drum 7) It is configured to be substantially trapezoidal so that the circumferential dimension W2 gradually decreases toward the outer dimension 24 toward the circumferential dimension W1. Therefore, the outer surface 24 of the ferromagnetic plate 15 is narrower than the inner surface 25. Regarding the rotation of the brake drum 7 in the direction of the arrow x, the front wall surface of the ferromagnetic plate 15 is made up of wall surfaces 26a, 26, 27, and the rear wall surface of the ferromagnetic plate 15 is made up of wall surfaces 28a, 28, 29. Wall surfaces 27 and 29 adjacent to the inner surface 25 of the ferromagnetic plate 15 are made parallel to a line extending radially outward from the rotation center of the brake drum 7 in order to secure the volume of the ferromagnetic plate 15. That is, the front wall surface 26 and the rear wall surface 28 are inclined substantially symmetrically with respect to the radial line passing between the two magnets 14a. When the guide tube 10 is cast from aluminum, the magnets 14a previously formed in the shape described above are arranged and cast into a mold. The magnets having the same polarity facing the common ferromagnetic plate 15 may be one continuous magnet.
[0012]
In the embodiment shown in FIG. 1, the portion 21 in contact with the wall surface 26a, 28a, 26, 28 of the outer tube portion 10a of the guide tube 10 has an acute angle and may be damaged by the influence of heat or the like. The portions adjacent to the outer surface 24 of the inclined wall surfaces 26, 28 are formed on the wall surfaces 26 a, 28 a substantially perpendicular to the outer peripheral surface of the guide cylinder 10, and are substantially perpendicular to the wall surfaces 26 a, 28 a substantially perpendicular to the outer surface 24 and the inner surface 25. Wall surfaces 26 and 28 inclined in opposite directions are formed between the inner wall surfaces 27 and 29 so that the circumferential dimension gradually decreases from the inner surface 25 toward the outer surface 24. Thereby, the stable coupling | bonding of the outer cylinder part 10a of the guide cylinder 10 and the ferromagnetic plate 15 is obtained.
[0013]
The present invention is not limited to the eddy current reduction device shown in FIG. 2, but can be applied to other types of eddy current reduction devices. In the embodiment shown in FIG. 5, a guide cylinder 10 made of a non-magnetic material and having an inner space with a rectangular cross section is disposed inside the brake drum 7 coupled to the rotary shaft 1. A large number of ferromagnetic plates 15 are arranged at equal intervals in the circumferential direction 10a, and the outer peripheral surfaces of a movable magnet support cylinder 14 and a stationary magnet support cylinder 34 made of a magnetic material arranged inside the guide cylinder 10 The magnets 14a and 34a are coupled so as to face the ferromagnetic plate 15 and the polarities with respect to the ferromagnetic plate 15 are alternately different in the circumferential direction, and the magnets 14a and 34a of the same polarity face the respective ferromagnetic plates 15 entirely. The movable magnet support cylinder 14 is switched by forward / reverse rotation by the actuator 20 between the braking position to be operated and the non-braking position shown in the figure where the magnets 14a and 34a having different polarities are opposed to the respective ferromagnetic plates 15 entirely. As shown in FIG. Circumferential dimension of the plate 15 is narrowed gradually once toward the inner surface 25 to outer surface 24.
[0014]
In the embodiment shown in FIG. 6, a guide cylinder 10 made of a non-magnetic material and having an inner space with a rectangular cross section is disposed inside the brake drum 7 coupled to the rotary shaft 1, and the outer cylinder portion of the guide cylinder 10 is arranged. A large number of ferromagnetic plates 15 are arranged at equal intervals in the circumferential direction 10a, and on the outer surface of a magnet support cylinder 14 made of a magnetic material arranged in the guide tube 10 so as to be movable in the axial direction, The magnets 14a are coupled so that the polarities are alternately different in the circumferential direction, and the magnet support cylinder 10 is protruded into the brake drum 7 so that each magnet 14a is opposed to each ferromagnetic plate 15 and the illustrated braking position. The magnet support cylinder 14 is retracted from the braking drum 7 in the axial direction, and each magnet 14a is switched to the non-braking position where it does not oppose each ferromagnetic plate 15, by the actuator 20, as shown in FIG. The circumferential dimension of the ferromagnetic plate 15 is the inner surface. Once directed to the Luo outer surface is narrowed gradually.
[0015]
As described above, according to the present invention, the shape of the cross section perpendicular to the rotation axis of the ferromagnetic plate 15 is substantially trapezoidal in which the outer surface 24 is narrower than the inner surface 25. After that, the magnetic flux exerted on the braking drum 7 is reduced. That is, when the magnetic flux of the two magnets 14a passes through the ferromagnetic plate 15 and reaches the brake drum 7, the magnetic flux density increases inside the brake drum 7, and eddy currents generated inside the brake drum 7 are generated. Strengthens and increases braking power.
[0016]
【The invention's effect】
In short, according to the present invention, a guide cylinder having a rectangular cross section made of a non-magnetic material is disposed inside a brake drum coupled to a rotating shaft, and a large number of circumferentially equally spaced outer cylinder parts of the guide cylinder are provided. A ferromagnetic plate is disposed on the outer peripheral surface of at least one magnet support cylinder made of a magnetic body that is axially movable or pivotable inside the guide cylinder. Brake positions where magnets are coupled one by one so that they are alternately different in direction, and the magnets of the same polarity face each ferromagnetic plate, and the non-braking positions where the magnet does not face each ferromagnetic plate In the eddy current reduction device, the front and rear wall surfaces adjacent to the inner surface facing the magnet of the ferromagnetic plate are first wall surfaces perpendicular to the inner surface, and the outer surface of the ferromagnetic plate facing the braking drum is The adjacent front and rear wall surfaces are second wall surfaces perpendicular to the outer surface, and the first Walls and the front and rear wall between the second wall, which circumferential spacing of the front and rear walls is inclined in mutually opposite directions such that countercurrent former gradually narrowed to the outer surface from the inner surface, the magnetic flux from the magnet Is reduced when passing through the ferromagnetic plate and reaches the braking drum, the magnetic flux density inside the braking drum is increased and the braking force is improved.
[Brief description of the drawings]
FIG. 1 is a front sectional view showing a main part of an eddy current reduction device according to an embodiment of the present invention.
FIG. 2 is a side sectional view showing an upper half portion of an eddy current reduction device to which the present invention is applied.
FIG. 3 is a front sectional view showing a non-braking state of the eddy current reduction device.
FIG. 4 is a front sectional view showing a braking state of the eddy current reduction device.
FIG. 5 is a side sectional view showing an upper half portion of another eddy current reduction device to which the present invention is applied.
FIG. 6 is a side sectional view showing an upper half portion of another eddy current reduction device to which the present invention is applied.
[Explanation of symbols]
W1, W2: Circumferential dimensions 1: Rotating shaft 6: Spoke 7: Braking drum 8: Heat radiation fin 10: Guide tube 10a: Outer tube portion 10b: Inner tube portion 14, 34: Magnet support tube 14a, 34a: Magnet 15: Ferromagnetic plate 20: Fluid pressure actuator 24: Outer surface 25: Inner surface 26: Side surface 27: Side surface 28: Side surface 29: Side surface

Claims

A guide cylinder having a rectangular inner section made of a non-magnetic material is disposed inside a brake drum coupled to the rotating shaft, and a large number of ferromagnetic plates are arranged at equal intervals in the circumferential direction on the outer cylinder of the guide cylinder. The polarity with respect to the ferromagnetic plate is alternately different in the circumferential direction on the outer peripheral surface of at least one magnet support cylinder made of a magnetic material that is arranged and can move axially or turn inside the guide cylinder. In an eddy current reduction device, the magnet is coupled to a braking position where the magnet of the same polarity completely faces each ferromagnetic plate and a non-braking position where the magnet does not entirely face each ferromagnetic plate . The front and rear wall surfaces adjacent to the inner surface of the ferromagnetic plate facing the magnet are first wall surfaces perpendicular to the inner surface, and the front and rear wall surfaces of the ferromagnetic plate adjacent to the outer surface facing the braking drum are A vertical second wall and front and back between the first wall and the second wall Wall surface, the eddy current reduction apparatus characterized by circumferential spacing of the front and rear walls is inclined in mutually opposite directions such that countercurrent former gradually narrowed to the outer surface from the inner surface.