Title of invention: Eddy current type speed reducer
Technical field
[0001]
　The present disclosure relates to a speed reducer mounted on a vehicle such as a truck or a bus as an auxiliary brake. In particular, the present disclosure relates to an eddy current type speed reducer that uses a permanent magnet to generate a braking force.
Background technology
[0002]
　Generally, an eddy current type speed reducer includes a cylindrical braking member. The braking member is fixed to the rotating shaft of the vehicle. Usually, a plurality of permanent magnets are arranged around the rotation axis on the inner peripheral side of the braking member. A plurality of pole pieces are arranged around the rotation axis in a gap between the inner peripheral surface of the braking member and the outer peripheral surface of the magnet. The switching mechanism switches the position of the magnet with respect to the pole piece, and switches between braking and non-braking.
[0003]
　The eddy current type speed reducer is classified into an axial slide type and a circumferential turning type according to the difference in the switching mechanism that switches the position of the magnet. The axial slide type eddy current type speed reducer is, as described in, for example, Registered Utility Model No. 2557740 (Patent Document 1), braking and non-braking by moving a magnet forward and backward by an actuator in a rotation axis direction. And switch. In the eddy current type speed reducer of Patent Document 1, a magnet is arranged in the braking member during braking, and the magnetic flux from the magnet reaches the braking member through the pole piece. On the other hand, during non-braking, the magnet moves in the direction of the rotation axis by the actuator and moves away from the braking member. Therefore, the magnetic flux from the magnet does not reach the braking member.
[0004]
　The axial slide type eddy current type speed reducer requires a large space for moving the magnet in the rotational axis direction. On the other hand, in the circumferential turning type eddy current type speed reducer, a magnet is moved in the circumferential direction of a braking member as described in, for example, Japanese Patent Application Laid-Open No. 2004-48963 (Patent Document 2). Since braking and non-braking are switched by, space saving can be realized.
[0005]
　In the eddy current type speed reducer of Patent Document 2, at the time of braking, each magnet substantially completely faces the pole piece, and the magnetic flux from the magnet reaches the braking member through the pole piece. That is, a magnetic circuit is formed between the magnet and the braking member. As a result, an eddy current is generated on the inner peripheral surface of the braking member that rotates integrally with the rotating shaft. As a result, the braking torque acts on the braking member, and the rotation speed of the rotating shaft decreases. On the other hand, during non-braking, the magnets move in the circumferential direction, and the magnets are arranged so as to straddle adjacent pole pieces. As a result, the magnetic flux from the magnet does not substantially reach the braking member. That is, a magnetic circuit is formed between the magnet and the pole piece, and no magnetic circuit is formed between the magnet and the braking member. Therefore, no eddy current is generated on the inner peripheral surface of the braking member, and no braking torque is generated.
[0006]
　The eddy current type speed reducers disclosed in Japanese Patent Laid-Open No. 2004-32927 (Patent Document 3) and Japanese Patent Laid-Open No. 2007-82333 (Patent Document 4) respectively include first and second magnets arranged around a rotation axis. The second magnet is arranged between the first magnet and the braking member, and is embedded inside the magnetic member. When switching between braking and non-braking, the first magnet moves in the circumferential direction, and the positional relationship between the first magnet and the second magnet is adjusted. According to Patent Documents 3 and 4, the magnetic fluxes from the first and second magnets are transmitted to the braking member during braking. At the time of non-braking, the first magnet and the second magnet are magnetically short-circuited with each other to form a breaking magnetic circuit.
Prior art documents
Patent literature
[0007]
Patent Document 1: Registered Utility Model No. 2557740
Patent Document 2: Japanese Patent Application Laid-Open No. 2004-48963
Patent Document 3: Japanese Patent Application Laid-Open No. 2004-32927
Patent Document 4: Japanese Patent Application Laid-Open No. 2007-82333
Summary of the invention
Problems to be Solved by the Invention
[0008]
　In recent years, the performance of vehicles has improved more and more. Therefore, the speed reducer is required to be able to generate a higher braking torque during braking. Further, the reduction gear transmission is required to be able to suppress the generation of inadvertent braking torque when not braking.
[0009]
　An object of the present disclosure is to provide an eddy current type speed reducer capable of generating a higher braking torque during braking while suppressing the generation of careless braking torque during non-braking.
Means for solving the problems
[0010]
　本開示の実施形態による渦電流式減速装置は、円筒状の制動部材と、複数の第１永久磁石と、円筒状の磁石保持部材と、複数の第２永久磁石と、複数のポールピースと、ステータと、スイッチング機構と、を備える。制動部材は、回転軸に固定される。第１永久磁石は、制動部材の内周面又は外周面と隙間を空けて対向する。第１永久磁石は、制動部材の円周方向に所定の間隔で配列される。第１永久磁石の各々は、制動部材の径方向に配置された一対の磁極を有する。磁石保持部材は、第１永久磁石を保持する。第２永久磁石は、上記隙間に設けられる。第２永久磁石は、第１永久磁石の配置角度と一致する配置角度で円周方向に配列される。第２永久磁石の各々は、円周方向に配置された一対の磁極を有する。ポールピースは、上記隙間に設けられる。ポールピースは、円周方向に隣接する第２永久磁石同士の間に配置されて第２永久磁石と接触する。ステータは、第２永久磁石及びポールピースを保持する。スイッチング機構は、磁石保持部材を回転させて、制動状態と非制動状態とを切り替える。第１永久磁石の磁極の配置は、円周方向に隣接する第１永久磁石同士で交互に反転する。第２永久磁石の磁極の配置は、円周方向に隣接する第２永久磁石同士で交互に反転する。第２永久磁石の各々は、上底と下底とを含む台形状の横断面を有する。上底は、制動部材側に配置される。下底は、第１永久磁石側に配置される。下底は、上底よりも長い。制動状態において、第２永久磁石の各々は、円周方向の一端部が一の第１永久磁石と径方向において重なるとともに、円周方向の他端部が他の第１永久磁石と径方向において重なるように配置される。このとき、一の第１永久磁石は、第２永久磁石の円周方向の一端部の磁極と同じ磁極を第２永久磁石側に有する。他の第１永久磁石は、第２永久磁石の円周方向の他端部の磁極と同じ磁極を第２永久磁石側に有する。非制動状態において、第２永久磁石の各々は、円周方向の一端部が一の第１永久磁石と径方向において重なるとともに、円周方向の他端部が他の第１永久磁石と径方向において重なるように配置される。このとき、一の第１永久磁石は、第２永久磁石の円周方向の一端部の磁極と異なる磁極を第２永久磁石側に有する。他の第１永久磁石は、第２永久磁石の円周方向の他端部の磁極と異なる磁極を第２永久磁石側に有する。
Effect of the invention
[0011]
　According to the eddy current type reduction gear transmission according to the embodiment of the present disclosure, it is possible to generate a higher braking torque during braking while suppressing the generation of inadvertent braking torque during non-braking.
Brief description of the drawings
[0012]
FIG. 1 is a vertical cross-sectional view schematically showing a speed reducer according to an embodiment of the present disclosure.
FIG. 2 is a perspective view showing an arrangement of first permanent magnets in the reduction gear transmission shown in FIG. 1.
FIG. 3 is a cross-sectional view showing a magnetic circuit during braking by the speed reducer shown in FIG. 1.
FIG. 4 is a cross-sectional view showing a magnetic circuit when the reduction gear transmission shown in FIG. 1 is not braking.
MODE FOR CARRYING OUT THE INVENTION
[0013]
　Hereinafter, embodiments of the present disclosure will be described. Note that, in the following description, the embodiments of the present disclosure will be described by way of examples, but the present disclosure is not limited to the examples described below. Although specific numerical values ​​and specific materials may be exemplified in the following description, the present disclosure is not limited to those examples.
[0014]
　本開示の実施形態による渦電流式減速装置は、円筒状の制動部材と、複数の第１永久磁石と、円筒状の磁石保持部材と、複数の第２永久磁石と、複数のポールピースと、ステータと、スイッチング機構と、を備える。制動部材は、回転軸に固定される。第１永久磁石は、制動部材の内周面又は外周面と隙間を空けて対向する。第１永久磁石は、制動部材の円周方向に所定の間隔で配列される。第１永久磁石の各々は、制動部材の径方向に配置された一対の磁極を有する。磁石保持部材は、第１永久磁石を保持する。第２永久磁石は、上記隙間に設けられる。第２永久磁石は、第１永久磁石の配置角度と一致する配置角度で円周方向に配列される。第２永久磁石の各々は、円周方向に配置された一対の磁極を有する。ポールピースは、上記隙間に設けられる。ポールピースは、円周方向に隣接する第２永久磁石同士の間に配置されて第２永久磁石と接触する。ステータは、第２永久磁石及びポールピースを保持する。スイッチング機構は、磁石保持部材を回転させて、制動状態と非制動状態とを切り替える。第１永久磁石の磁極の配置は、円周方向に隣接する第１永久磁石同士で交互に反転する。第２永久磁石の磁極の配置は、円周方向に隣接する第２永久磁石同士で交互に反転する。第２永久磁石の各々は、上底と下底とを含む台形状の横断面を有する。上底は、制動部材側に配置される。下底は、第１永久磁石側に配置される。下底は、上底よりも長い。制動状態において、第２永久磁石の各々は、円周方向の一端部が一の第１永久磁石と径方向において重なるとともに、円周方向の他端部が他の第１永久磁石と径方向において重なるように配置される。このとき、一の第１永久磁石は、第２永久磁石の円周方向の一端部の磁極と同じ磁極を第２永久磁石側に有する。他の第１永久磁石は、第２永久磁石の円周方向の他端部の磁極と同じ磁極を第２永久磁石側に有する。非制動状態において、第２永久磁石の各々は、円周方向の一端部が一の第１永久磁石と径方向において重なるとともに、円周方向の他端部が他の第１永久磁石と径方向において重なるように配置される。このとき、一の第１永久磁石は、第２永久磁石の円周方向の一端部の磁極と異なる磁極を第２永久磁石側に有する。他の第１永久磁石は、第２永久磁石の円周方向の他端部の磁極と異なる磁極を第２永久磁石側に有する。
[0015]
　According to the speed reducer of the present embodiment, the operation of the switching mechanism causes the magnet holding member to rotate relative to the stator, and switches between the braking state and the non-braking state. Since the cross-sectional shape of each second permanent magnet is trapezoidal, one pole piece and two second pole pieces contacting this pole piece are provided for one first permanent magnet in both the braking state and the non-braking state. 2. The circumferential ends of the permanent magnets overlap in the radial direction. That is, when the second permanent magnets arranged in the circumferential direction are viewed from the inner peripheral side or the outer peripheral side, the end portions of the respective second permanent magnets overlap the first permanent magnets. However, in the braking state, the magnetic pole at the end of the second permanent magnet that overlaps with the first permanent magnet (eg, N pole) is the magnetic pole on the side facing the second permanent magnet of the first permanent magnet (eg, N pole). Is the same as. On the other hand, in the non-braking state, the magnetic pole at the end of the second permanent magnet that overlaps the first permanent magnet (eg, S pole) is the magnetic pole on the side facing the second permanent magnet of the first permanent magnet (eg: (N pole). In the present embodiment, the cross section means a cross section perpendicular to the rotation axis.
[0016]
　In the braking state, a magnetic circuit formed by the first permanent magnets is provided between the first permanent magnets adjacent to each other in the circumferential direction, the pole pieces adjacent to each other in the circumferential direction, the magnet holding member, and the braking member. It is formed. Further, a magnetic circuit formed by the second permanent magnet is formed between the second permanent magnet, the pole pieces adjacent to each other in the circumferential direction, and the braking member.
[0017]
　Therefore, according to the reduction gear transmission of the present embodiment, the magnetic flux from the second permanent magnet is superimposed on the magnetic flux from the first permanent magnet during braking, and the strong magnetic flux thus enhanced reaches the braking member. Therefore, a large eddy current is generated by the braking member that rotates integrally with the rotating shaft. This makes it possible to obtain a high braking torque.
[0018]
　On the other hand, in the non-braking state, the magnetism of the first and second permanent magnets is mainly present between the first permanent magnets adjacent to each other in the circumferential direction, the second permanent magnet, and the magnet holding member. A circuit is formed.
[0019]
　Therefore, according to the speed reducer of the present embodiment, the magnetic flux leaking from the first and second permanent magnets to the braking member is small during non-braking. Therefore, the eddy current generated in the braking member that rotates integrally with the rotating shaft is small, and it is possible to suppress the generation of careless braking torque.
[0020]
　In a typical example of the reduction gear transmission of the present embodiment, the plurality of first permanent magnets are arranged on the inner peripheral side of the braking member and face the inner peripheral surface of the braking member with a gap. In this case, the plurality of second permanent magnets and the plurality of pole pieces are arranged in the gap between the inner peripheral surface of the braking member and the outer peripheral surfaces of the plurality of first permanent magnets. The arrangement angle of the plurality of second permanent magnets around the rotation axis matches the arrangement angle of the plurality of first permanent magnets around the rotation axis. The arrangement angles of the plurality of pole pieces around the rotation axis also match the arrangement angles of the plurality of first permanent magnets around the rotation axis.
[0021]
　In the speed reducer of the present embodiment, the corners of the second permanent magnet having a trapezoidal cross section may be rounded. That is, in the trapezoidal cross section of the second permanent magnet, the upper base and the hypotenuse and/or the lower base and the hypotenuse may be connected by an arc. Alternatively, the corners of the second permanent magnet having a trapezoidal cross section may be chamfered. That is, in the trapezoidal cross section of the second permanent magnet, a straight line portion may be provided between the upper bottom and the hypotenuse and/or between the lower bottom and the hypotenuse.
[0022]
　In a typical example of the reduction gear transmission of the present embodiment, a first air gap is provided between the circumferential ends of the second permanent magnets that are adjacent to each other in the circumferential direction, and the first air gap is slightly magnetic. It becomes resistance. During braking, the first permanent magnets and the second permanent magnets are provided between the first permanent magnets adjacent to each other in the circumferential direction, the pole pieces adjacent to each other in the circumferential direction, the magnet holding member, and the braking member. A magnetic circuit is formed. At that time, the magnetic flux emitted from the N pole of the first permanent magnet is effectively introduced into the pole piece through the first air gap while strengthening the magnetic flux emitted from the N pole of the second permanent magnet. Further, the magnetic flux introduced from the braking member to the pole piece is effectively attracted to the S pole of the second magnet and effectively reaches the S pole of the first permanent magnet through the first gap. That is, the first air gap also serves as a magnetic flux passage. Therefore, the amount of magnetic flux exchanged between the first and second permanent magnets and the pole piece and the pole piece is effectively ensured.
[0023]
　In a typical example of the reduction gear transmission of the present embodiment, a second gap is provided between the circumferential ends of the pole pieces that are circumferentially adjacent to each other. During braking, a magnetic circuit of the second permanent magnet is formed between the second permanent magnet, the pole pieces adjacent to each other in the circumferential direction, and the braking member. At that time, the second air gap effectively suppresses the short circuit of the magnetic flux from one pole piece to the other pole piece. It is also possible to suppress self-shorting of magnetic flux in the second permanent magnet.
[0024]
　Hereinafter, an embodiment of the eddy current type speed reducer of the present disclosure will be described in detail.
[0025]
　FIG. 1 is a vertical sectional view schematically showing the speed reducer according to the present embodiment. FIG. 2 is a perspective view showing an arrangement of the first permanent magnets in the speed reducer shown in FIG. 3 and 4 are cross-sectional views showing a magnetic circuit of the speed reducer shown in FIG. Of these figures, FIG. 3 shows the state during braking, and FIG. 4 shows the state during non-braking. 3 and 4, the magnetic circuit is schematically shown by a solid line, and the direction of the magnetic flux is shown by an arrow on the solid line. Here, the vertical section is a section along the rotation axis. The cross section is a cross section perpendicular to the rotation axis.
[0026]
　With reference to FIGS. 1 to 4, the reduction gear device includes a cylindrical braking member 1 and a cylindrical magnet holding member 2 disposed inside the braking member 1. The braking member 1 is fixed to a rotating shaft 10 (eg, propeller shaft, drive shaft, etc.) of the vehicle via a rotor support member 6 (see FIG. 1). As a result, the braking member 1 rotates integrally with the rotating shaft 10. Thick line arrows in FIGS. 3 and 4 indicate an example of the rotation direction of the braking member 1. Radiating fins 1a are provided on the outer peripheral surface of the braking member 1 (see FIG. 1). The heat radiation fin 1a plays a role of cooling the braking member 1 itself.
[0027]
　The magnet holding member 2 forms a pair with the braking member 1 and is arranged concentrically with the braking member 1. The magnet holding member 2 is arranged slidably with respect to the stator support member 7 fixed to the non-rotating portion 11 (eg, transmission cover) of the vehicle via, for example, a ring-shaped slide plate. That is, the magnet holding member 2 is supported so as to be rotatable relative to the rotating shaft 10. In other words, the magnet holding member 2 is supported by the non-rotating portion 11 via the stator supporting member 7 so as not to rotate integrally with the rotating shaft 10.
[0028]
　With reference to FIGS. 1 and 2, a plurality of first permanent magnets 3 are fixed to the outer peripheral surface of the magnet holding member 2. The first permanent magnets 3 face the inner peripheral surface 1b of the braking member 1 with a gap therebetween, and are arranged at predetermined intervals in the circumferential direction of the braking member 1 and the magnet holding member 2 with the rotating shaft 10 as the center. . That is, the first permanent magnets 3 are provided at intervals in the circumferential direction over the entire circumference of the magnet holding member 2. The first permanent magnets 3 each have a pair of magnetic poles (N pole, S pole). The pair of magnetic poles (N pole, S pole) are arranged in the radial direction of the braking member 1 and the magnet holding member 2 with the rotating shaft 10 as the center. The arrangement of the magnetic poles (N pole, S pole) of the first permanent magnets 3 is alternately reversed between the first permanent magnets 3 adjacent to each other in the circumferential direction (see FIGS. 2 to 4). The material of the magnet holding member 2 is a ferromagnetic material (eg, carbon steel, cast iron, etc.).
[0029]
　With reference to FIGS. 1, 3 and 4, a plurality of second permanent magnets 4 and a plurality of ferromagnetic bodies are provided in the gap between the inner peripheral surface 1 b of the braking member 1 and the outer peripheral surface of the first permanent magnet 3. The pole piece 5 is provided. The second permanent magnets 4 are arranged in the circumferential direction of the braking member 1 around the rotation shaft 10. The second permanent magnets 4 each have a pair of magnetic poles (N pole, S pole) arranged in the circumferential direction. The arrangement of the magnetic poles (N pole, S pole) of the second permanent magnets 4 is alternately inverted between the second permanent magnets 4 adjacent to each other in the circumferential direction (see FIGS. 3 and 4). The pole piece 5 is arranged between the second permanent magnets 4 that are adjacent to each other in the circumferential direction, and contacts the second permanent magnet 4. The arrangement angle of the plurality of second permanent magnets 4 around the rotation axis 10 matches the arrangement angle of the plurality of first permanent magnets 3 around the rotation axis 10. The arrangement angle of the plurality of pole pieces 5 around the rotation axis 10 also matches the arrangement angle of the plurality of first permanent magnets 3 around the rotation axis 10.
[0030]
　The plurality of second permanent magnets 4 and the plurality of pole pieces 5 are held by ring-shaped stators 8 on both sides thereof. The second permanent magnets 4 and the pole pieces 5 are arranged around the entire circumference of the stator 8. The stator 8 is fixed to the stator support member 7. That is, the stator 8 is supported by the stator support member 7 so as to be rotatable relative to the rotating shaft 10 (see FIG. 1 ). In other words, the stator 8 is supported by the non-rotating portion 11 via the stator support member 7 so as not to rotate integrally with the rotating shaft 10 of the vehicle.
[0031]
　3 and 4, the cross section (transverse cross section) of each second permanent magnet 4 perpendicular to the rotation axis 10 is trapezoidal. As shown in FIG. 4, each of the second permanent magnets 4 includes an upper bottom 4a, a lower bottom 4b, and hypotenuses 4c and 4c when viewed in cross section. The upper bottom 4a is arranged on the braking member 1 side. The lower bottom 4b is longer than the upper bottom 4a, and is arranged on the first permanent magnet 3 side. Each hypotenuse 4c connects the upper bottom 4a and the lower bottom 4b. Each hypotenuse 4c forms an acute angle (an angle larger than 0° and smaller than 90°) with the lower bottom 4b. When the hypotenuse 4c and the lower bottom 4b are connected by an arc or another straight line, the angle formed by the extension line of the hypotenuse 4c and the extension of the lower bottom 4b is an acute angle. The second permanent magnet 4 has a thickness (a dimension in the radial direction) that decreases toward both ends in the circumferential direction in a cross-sectional view. That is, in the second permanent magnet 4, the volume at both end portions in the circumferential direction is smaller than the volume at the central portion in the circumferential direction.
[0032]
　The cross section of each second permanent magnet 4 is preferably substantially isosceles trapezoidal. In this case, by design, the shape of the second permanent magnet 4 may be an isosceles trapezoidal shape, and asymmetry caused by a dimensional error at the time of manufacture is allowed.
[0033]
　Referring to FIG. 4, the cross section (transverse cross section) of each pole piece 5 perpendicular to the rotation axis 10 is substantially pentagonal (home base shape). Each of the pole pieces 5 has a bottom side 5a facing the braking member 1, opposite sides 5b and 5b extending from both ends of the bottom side 5a to the second permanent magnet 4 side, and a hypotenuse 4c of the second permanent magnet 4 in cross-sectional view. And the hypotenuses 5c and 5c which contact with. The pole piece 5 has a thickness (a dimension in the radial direction) that increases toward the central portion in the circumferential direction in the cross-sectional view. The maximum thickness of the pole piece 5 is larger than the maximum thickness of the second permanent magnet 4. In the pole piece 5, the volume at the center in the circumferential direction is larger than the volume at both ends in the circumferential direction.
[0034]
　Continuing to refer to FIG. 4, the first gap G1 is provided between the circumferentially adjacent ends of the second permanent magnets 4 that are circumferentially adjacent to each other. The first gap G1 contacts the surface of the pole piece 5 on the side closer to the first permanent magnet 3. Since the maximum thickness of the pole piece 5 is larger than the maximum thickness of the second permanent magnet 4, the second gap G2 is provided between the circumferential ends of the adjacent pole pieces 5 in the circumferential direction. The second gap G2 is formed between the opposite sides 5b of the pole pieces 5 adjacent to each other in the circumferential direction. The second gap G2 contacts the surface of the second permanent magnet 4 on the side closer to the braking member 1 (upper bottom 4a). The first gap G1 is a gap between the second permanent magnets 4 adjacent to each other, and may be a simple space (air) or may be filled with a non-magnetic material. Similarly, the second gap G2 is a gap between the pole pieces 5 adjacent to each other, and may be a mere space (air) or may be filled with a non-magnetic material.
[0035]
　The switching mechanism rotates the magnet holding member 2. As a switching mechanism, a lever 2a projects from the side surface of the magnet holding member 2 (see FIG. 1). A drive device such as an air cylinder or an electric actuator (not shown) is connected to the lever 2a via a link mechanism (not shown). At the time of switching between braking and non-braking, the magnet holding member 2 and the first permanent magnet 3 rotate integrally by the operation of the drive device. As a result, the positions of the first permanent magnet 3, the second permanent magnet 4, and the pole piece 5 take the following two states (braking state and non-braking state).
[0036]
　With reference to FIG. 3, at the time of braking, one pole piece 5 and two second permanent magnets 4 in contact with the pole piece 5 have radial end portions in the radial direction with respect to one first permanent magnet 3. In (radial view). In other words, each of the first permanent magnets 3 is arranged so as to straddle two adjacent second permanent magnets 4 in the circumferential direction, and the ends of the second permanent magnets 4 (between the lower bottom 4b and the hypotenuse 4c) are arranged. Facing the corner (Fig. 4)). At this time, the magnetic pole at the end of the second permanent magnet 4 overlapping the first permanent magnet 3 (example: N pole) is the magnetic pole on the side facing the second permanent magnet 4 of the first permanent magnet 3 (example: N pole). ) Is the same. On the other hand, referring to FIG. 4, during non-braking, one pole piece 5 and two second poles 5 that contact the pole piece 5 are provided for one first permanent magnet 3 as in the case of braking. The circumferential ends of the permanent magnets 4 overlap in the radial direction (as viewed in the radial direction). In other words, each of the first permanent magnets 3 is arranged so as to straddle two adjacent second permanent magnets 4 in the circumferential direction, and the ends of the second permanent magnets 4 (between the lower bottom 4b and the hypotenuse 4c) are arranged. Facing the corner). At this time, the magnetic pole at the end of the second permanent magnet 4 overlapping the first permanent magnet 3 (example: S pole) is the magnetic pole on the side of the first permanent magnet 3 facing the second permanent magnet 4 (example: N pole). ) Different. By switching the magnet holding member 2 relative to the stator 8 by the arrangement angle of the first permanent magnet 3 (second permanent magnet 4, pole piece 5), switching between braking and non-braking is performed.
[0037]
　Referring to FIG. 3, in the braking state, the magnetic flux emitted from the N pole of one of the first permanent magnets 3 adjacent in the circumferential direction is the first permanent magnet 3 of the one permanent magnet 3. Is superposed on the magnetic flux emitted from the N poles of the two second permanent magnets 4 overlapping with each other, and is introduced into the pole piece 5 overlapping with the one first permanent magnet 3 through the first gap G1. The magnetic flux introduced into the pole piece 5 reaches the braking member 1 that faces the pole piece 5 and one of the first permanent magnets 3. The magnetic flux that has reached the braking member 1 is introduced into the pole piece 5 that overlaps the other first permanent magnet 3 and reaches the S pole of the other first permanent magnet 3. The magnetic flux emitted from the N pole of the other first permanent magnet 3 reaches the S pole of one of the first permanent magnets 3 through the magnet holding member 2.
[0038]
　At that time, the magnetic flux emitted from the N pole of the second permanent magnet 4 overlaps with the magnetic flux emitted from the N pole of the first permanent magnet 3 overlapping the N pole of the second permanent magnet 4, and the magnetic flux of the second permanent magnet 4 It is introduced into the pole piece 5 that contacts the north pole. The magnetic flux introduced into the pole piece 5 reaches the braking member 1 that faces the pole piece 5 and one of the first permanent magnets 3. The magnetic flux that has reached the braking member 1 reaches the S pole of the second permanent magnet 4 through the pole piece 5 that contacts the S pole of the second permanent magnet 4.
[0039]
　That is, at the time of braking, the first permanent magnets 3 that are adjacent to each other in the circumferential direction, the pole pieces 5 that are adjacent to each other in the circumferential direction, the magnet holding member 2, and the braking member 1 are provided with the first permanent magnets. A magnetic circuit of 3 is formed. Further, a magnetic circuit is formed by the second permanent magnet 4 between the second permanent magnet 4, the pole pieces 5 adjacent to each other in the circumferential direction, and the braking member 1. Such a magnetic circuit is formed in such a manner that the directions of the magnetic flux are alternately reversed over the entire area in the circumferential direction.
[0040]
　When a magnetic field acts on the braking member 1 from the first and second permanent magnets 3 and 4 in a state where a relative rotational speed difference is generated between the first and second permanent magnets 3 and 4 and the braking member 1, Eddy current is generated on the inner peripheral surface 1b of the braking member 1 facing the first permanent magnet 3. Due to the interaction between this eddy current and the magnetic flux densities from the first and second permanent magnets 3 and 4, according to Fleming's left-hand rule, the braking member 1 rotating integrally with the rotating shaft 10 is rotated in the opposite direction to the rotating direction. Braking torque is generated.
[0041]
　Therefore, according to the speed reducer of the present embodiment, the magnetic flux from the second permanent magnet 4 is superimposed on the magnetic flux from the first permanent magnet 3 during braking, and the strong magnetic flux thus enhanced reaches the braking member 1. .. Therefore, a large eddy current is generated in the braking member 1 that rotates integrally with the rotating shaft 10. This makes it possible to obtain a high braking torque.
[0042]
　On the other hand, referring to FIG. 4, in the non-braking state, the magnetic flux emitted from the N pole of one of the first permanent magnets 3 adjacent to each other in the circumferential direction immediately becomes The S poles of the two second permanent magnets 4 overlapping the one first permanent magnet 3 are reached. The magnetic flux emitted from the N pole of the second permanent magnet 4 immediately reaches the S pole of the other first permanent magnet 3 overlapping the N pole of the second permanent magnet 4. The magnetic flux emitted from the N pole of the other first permanent magnet 3 reaches the S pole of one of the first permanent magnets 3 through the magnet holding member 2.
[0043]
　That is, at the time of non-braking, the magnetic circuit formed by the first and second permanent magnets 3 and 4 is provided between the first permanent magnets 3 adjacent to each other in the circumferential direction, the second permanent magnet 4, and the magnet holding member 2. Is formed. Such a magnetic circuit is formed by alternately arranging the magnetic fluxes in opposite directions over the entire area in the circumferential direction.
[0044]
　Therefore, according to the speed reducer of the present embodiment, the magnetic fluxes from the first and second permanent magnets 3 and 4 do not reach the braking member 1 reliably during non-braking. That is, careless magnetic flux leakage from the first and second permanent magnets 3 and 4 to the braking member 1 can be suppressed. Therefore, no eddy current is generated in the braking member 1 that rotates integrally with the rotating shaft 10, and it is possible to suppress the generation of inadvertent braking torque.
[0045]
　For example, the material of the braking member 1 is a ferromagnetic material (eg, carbon steel, cast iron, etc.). A copper plating layer having high conductivity may be formed on the inner peripheral surface 1b of the braking member 1. When the copper plating layer is formed on the inner peripheral surface 1b of the braking member 1, the eddy current generated on the inner peripheral surface 1b of the braking member 1 during braking increases. As a result, the braking torque can be further improved.
[0046]
　Generally, in a permanent magnet, the linearity of the magnetic flux emitted from the central portion in the arrangement direction of the magnetic poles (N pole, S pole) is small, and the linearity of the magnetic flux emitted from both ends in the arrangement direction of the magnetic pole is large. In consideration of this point, the second permanent magnet 4 is formed in a trapezoidal shape in a cross-sectional view so that the volume becomes smaller toward both ends in the circumferential direction. Thereby, the magnetic flux emitted from both ends of the second permanent magnet 4 can be reduced, and it is possible to prevent the magnetic flux from leaking from one of the adjacent second permanent magnets 4 to the other during braking. Further, the pole pieces 5 arranged between the second permanent magnets 4 adjacent to each other are formed in a pentagonal shape in a cross-sectional view so that the volume increases toward the central portion in the circumferential direction. There is. With such a pole piece 5, during braking, the magnetic flux leakage from one of the second permanent magnets 4 adjacent to each other to the other is more reliably suppressed, and the magnetic flux emitted from each second permanent magnet 4 is applied to the braking member 1 side. (Fig. 3). Therefore, according to the speed reducer of the present embodiment, it is possible to effectively generate the braking torque.
[0047]
　In the reduction gear transmission of the present embodiment, the second gap G2 is provided between the pole pieces 5 adjacent to each other. The surface (upper bottom 4a) of the second permanent magnet 4 on the braking member 1 side is exposed to the second gap G2. That is, the surface of the second permanent magnet 4 on the braking member 1 side is not covered with a ferromagnetic material such as the pole piece 5. Therefore, at the time of braking, it is possible to prevent the magnetic flux emitted from the second permanent magnet 4 from returning to the second permanent magnet 4 (self-short circuit) without reaching the braking member 1 and effectively reducing the braking torque. Can be generated.
[0048]
　In the speed reducer of the present embodiment, the first gap G1 is provided between the second permanent magnets 4 adjacent to each other and between the first permanent magnet 3 and the pole piece 5. As described above, the first gap G1 is a space (air) or is filled with a non-magnetic material, and thus has a large magnetic resistance. Therefore, during non-braking, it is possible to prevent the magnetic flux emitted from the first permanent magnet 3 from leaking to the pole piece 5 side, and the magnetic flux emitted from the first permanent magnet 3 can be more reliably caused to the second permanent magnet 4 side. (Fig. 4). As a result, it is possible to effectively suppress the generation of careless braking torque during non-braking.
[0049]
　The first gap G1 does not substantially hinder the formation of a magnetic circuit by the first and second permanent magnets 3 and 4 during braking. More specifically, at the time of braking, the first and second permanent magnets 3, 4 are provided between the braking member 1, the magnet holding member 2, and the circumferentially adjacent first permanent magnets 3 and the pole pieces 5. To form a magnetic circuit. At that time, the magnetic flux emitted from the N pole of one of the first permanent magnets 3 effectively strengthens the magnetic flux emitted from the N pole of the second permanent magnet 4 and effectively passes through the first gap G1 to the one pole piece 5. be introduced. The magnetic flux introduced into one pole piece 5 passes through the braking member 1 and is introduced into the other pole piece 5, and then is attracted to the S pole of the second permanent magnet 4, thereby passing through the first gap G1 and the other. Effectively reaches the S pole of the first permanent magnet 3. Therefore, the amount of magnetic flux exchanged between the first and second permanent magnets 3 and 4 and the pole piece 5 is sufficiently secured. In this way, the first gap G1 can serve as a magnetic flux passage, although it has a slight magnetic resistance during braking.
[0050]
　In addition, it goes without saying that the present disclosure is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present disclosure.
Industrial availability
[0051]
　The eddy current type speed reducer of the present disclosure is useful as an auxiliary brake for all vehicles.
Explanation of symbols
[0052]
　　1 Braking member
　　1b Inner peripheral surface of braking member
　　2 Magnet holding member
　　3 First permanent magnet
　　4 Second permanent magnet
　　4a Upper
　　bottom 4b of second permanent magnet 4b Lower bottom
　　4c of second permanent magnet Oblique side
　　5 of second permanent magnet 5 Pole piece
　　8 Stator
　　10 Rotation axis
The scope of the claims
[Claim 1]
　A plurality of first braking members that are fixed to the rotating shaft and that
　face the inner circumferential surface or the outer circumferential surface of the braking member with a gap and are arranged at predetermined intervals in the circumferential direction of the braking member. A permanent magnet, the first permanent magnet having a pair of magnetic poles arranged in the radial direction of the braking member,
　a cylindrical magnet holding member holding the first permanent magnet, and the first permanent magnet
　being provided in the gap. A plurality of second permanent magnets arranged in the circumferential direction at an arrangement angle that matches the arrangement angle of the first permanent magnet, the second permanent magnets each having a pair of magnetic poles arranged in the circumferential direction. A permanent magnet,
　a plurality of pole pieces provided in the gap and arranged between the second permanent magnets adjacent to each other in the circumferential direction, and in contact with
　the second permanent magnet ; the second permanent magnet; A stator that holds the pole piece; and a
　switching mechanism that rotates the magnet holding member to switch between a braking state and a non-braking state, and the
　magnetic poles of the first permanent magnet are arranged in the circumferential direction. alternately inverted by the first permanent magnet adjacent to,
　the arrangement of the magnetic poles of the second permanent magnet is alternately inverted in the second permanent magnets adjacent to each other in the circumferential direction,
　the second permanent magnet Each has a trapezoidal cross section including an upper bottom arranged on the braking member side and a lower bottom arranged on the first permanent magnet side and longer than the upper bottom,
　In the braking state, each of the second permanent magnets has a first permanent magnet whose one end in the circumferential direction has the same magnetic pole as the magnetic pole of the one end on the second permanent magnet side, and the diameter. Is arranged so that the other end in the circumferential direction overlaps in the radial direction with another first permanent magnet having the same magnetic pole as the magnetic pole of the other end on the second permanent magnet side. In the
　non-braking state, each of the second permanent magnets includes one first permanent magnet having a magnetic pole different from the magnetic pole of the one end at the one end in the circumferential direction on the second permanent magnet side. While overlapping in the radial direction, the other end in the circumferential direction overlaps in the radial direction with another first permanent magnet having a magnetic pole different from the magnetic pole of the other end on the second permanent magnet side. Eddy current type speed reducer.
[Claim 2]
　The eddy current reduction device according to claim 1,
　wherein a first air gap is provided between the circumferentially adjacent ends of the second permanent magnets adjacent to each other in the circumferential direction. ..
[Claim 3]
　The eddy current reduction gear according to claim 1 or 2,
　wherein a second air gap is provided between the circumferential ends of the pole pieces adjacent to each other in the circumferential direction. ..