Magnetoviscous fluid apparatus

Abstract

The present invention provides a magnetoviscous fluid apparatus equipped with a one-way clutch that can suppress the influence of a magnetic field on the one-way clutch. [Solution] The present invention comprises a first shaft made of a non-magnetic material and rotatable around an axis, a second shaft made of a non-magnetic material and rotatable relative to the first shaft around an axis, a rotating plate fixed to the second shaft, a housing for housing the first shaft, the second shaft, and the rotating plate, a magnetoviscous fluid sealed in the housing and interposed between the rotating plate and the housing, a magnetic field generating unit for generating a magnetic field to be applied to the magnetoviscous fluid, and a one-way clutch disposed between the first shaft and the second shaft, wherein the one-way clutch is configured to transmit rotation of the first shaft in one direction to the second shaft, but not to transmit rotation of the first shaft in the other direction to the second shaft, and the one-way clutch is covered by the first shaft and the second shaft.

Description

Technical Field

[0004] , ,

[0005] , ,

[0001] The present invention relates to a magnetorheological fluid device.

Background Art

[0002] Conventionally, a rotary damper using a magnetorheological fluid has been known. In this type of rotary damper, by energizing an electromagnetic coil, the viscosity of the magnetorheological fluid can be changed to generate a braking torque with respect to rotation. Further, as a rotary damper having one-way rotation, as shown in Patent Document 1, a rotary damper including a damper body, a speed reduction mechanism for amplifying the braking torque generated in the damper body, and a one-way clutch provided in a braking torque transmission path from the rotation shaft of the damper body to the rotation shaft of the speed reduction mechanism has been proposed. In this rotary damper, the one-way clutch can apply a braking torque during rotation in one direction and suppress the transmission of the braking torque during rotation in the other direction.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when a one-way clutch is incorporated into a magnetorheological fluid device, the one-way clutch may be affected by a magnetic field. That is, in a magnetorheological fluid device, a magnetic field generating unit for applying a magnetic field to the magnetorheological fluid is provided. On the other hand, a one-way clutch is generally composed of components containing a magnetic material. Therefore, when the one-way clutch is arranged near the magnetic field generating unit, there is a risk that magnetic flux concentrates on the one-way clutch or the one-way clutch is magnetized, which may hinder the smooth engagement or free rotation of the one-way clutch.

[0005] Furthermore, if magnetic flux leaks to the one-way clutch side, it may become difficult to apply a sufficient magnetic field to the area where the magnetorheological fluid is located, potentially making it difficult to stably generate a load from the magnetorheological fluid.

[0006] The present invention has been made to solve the above problems, and aims to provide a magnetoviscous fluid apparatus equipped with a one-way clutch that can suppress the influence of a magnetic field on the one-way clutch. [Means for solving the problem]

[0007] Item 1. A first shaft body made of a non-magnetic material and rotatable around its axis, A second shaft, formed of a non-magnetic material and capable of relative rotation around an axis with respect to the first shaft, A rotating plate fixed to the second shaft body, A housing section that houses the first shaft, the second shaft, and the rotating plate, A magnetorheological fluid is sealed in the aforementioned housing and interposed between the rotating plate and the housing, A magnetic field generating unit that generates a magnetic field to be applied to the magnetoviscous fluid, A one-way clutch positioned between the first shaft and the second shaft, Equipped with, The one-way clutch is configured to transmit rotation of the first shaft in one direction to the second shaft, and not to transmit rotation of the first shaft in the other direction to the second shaft. The one-way clutch is covered by the first shaft and the second shaft. Magnetoviscosal fluid apparatus.

[0008] Item 2. The one-way clutch is positioned radially between the first shaft and the second shaft. A magnetorheological fluid apparatus as described in item 1.

[0009] Item 3. The one-way clutch is positioned radially inward of the coil of the magnetic field generating unit. A magnetorheological fluid apparatus as described in item 1 or 2.

[0010] Item 4. The housing section is, A first yoke having a first opposing surface that faces one main surface of the rotating plate via a first gap, A second yoke having a second opposing surface that faces the other main surface of the rotating plate via a second gap, Equipped with, The magnetorheological fluid is filled into the first gap and the second gap. The aforementioned magnetic field generating unit is A coil, the first yoke, and the second yoke are included, and when the coil is energized, a magnetic path is formed passing through the first yoke, the second yoke, the rotating plate, and the magnetoviscous fluid. A magnetorheological fluid apparatus as described in any of items 1 to 3.

[0011] Item 5. Further comprising a reduction mechanism located outside the housing section, The reduction mechanism is connected to the first shaft body protruding from the housing and is configured to reduce the rotation of the first shaft body and output the result. A magnetorheological fluid apparatus as described in any of items 1 to 4.

[0012] Item 6. In the aforementioned housing section, At least one corner formed on the surface facing the first shaft and the second shaft is formed in an arc shape. A magnetorheological fluid apparatus as described in any of items 1 to 5. [Effects of the Invention]

[0013] According to the present invention, in a magnetorheological fluid apparatus equipped with a one-way clutch, the influence of a magnetic field on the one-way clutch can be suppressed. [Brief explanation of the drawing]

[0014] [Figure 1] This is a perspective view of a magnetoviscous fluid apparatus according to one embodiment of the present invention. [Figure 2] This is a cross-sectional view of Figure 1. [Figure 3] It is a perspective view showing the structure of the shaft body in order. [Figure 4] It is a cross-sectional view of the shaft body. [Figure 5] It is a perspective view showing a state where a rotating plate, a second bearing, and a C-ring are attached to the shaft body. [Figure 6] It is a perspective view showing a state where a first yoke is arranged below the rotating plate. [Figure 7] It is a perspective view showing a state where a second yoke is arranged with respect to FIG. 6. [Figure 8] It is a perspective view of the cover member. [Figure 9] It is a cross-sectional view showing the magnetic path of the magnetorheological fluid device. [Figure 10] It is a cross-sectional view showing another example of the magnetorheological fluid device of the present invention.

Embodiments for Carrying out the Invention

[0015] <1. Overview of the Magnetorheological Fluid Device> Hereinafter, an embodiment of the magnetorheological fluid device 10 of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of the magnetorheological fluid device, and FIG. 2 is a cross-sectional view of FIG. 1. This magnetorheological fluid device mainly includes a shaft body 1, a rotating plate 2, a first yoke 3, a second yoke 4, and a cover member 5. Hereinafter, each member will be described in detail. However, FIGS. 3, 5, and 6 described later do not show the order of assembly, but are diagrams for showing the structure of the magnetorheological fluid device and the positional relationship of the members in detail. The order of assembly will be described later. Also, in the following description, for the sake of convenience of explanation, the description will be made according to the direction shown in FIG. 2, but this direction does not limit the invention, and the magnetorheological fluid device of the present invention can be arranged along various directions.

[0016] <1-1. Shaft Body> FIG. 3 is a perspective view showing the structure of the shaft body in order, and FIG. 4 is a cross-sectional view of the shaft body. The shaft body 1 has a first shaft portion (second shaft body) 6, a second shaft portion (first shaft body) 7, a third shaft portion (first shaft body) 8, and a one-way clutch 9.

[0017] Figure 3(a) is a perspective view of the first shaft portion. As shown in Figure 3(a), the first shaft portion 6 is integrally connected in the axial direction by a first portion 61, a second portion 62, a third portion 63, and a fourth portion 64 in that order. The first portion 61 is formed in a cylindrical shape, and a plurality of annular grooves 611 are formed on its outer circumferential surface, spaced apart in the axial direction. X-rings 65 are fitted into each of these grooves 611, as will be described later.

[0018] The second part 62 is formed in a cylindrical shape with a smaller diameter than the first part 61. The third part 63 is formed in a cylindrical shape with a smaller diameter than the second part 62. The fourth part 64 is also formed in a cylindrical shape with a smaller diameter than the third part 63. A groove 641 is formed on the outer circumferential surface near the upper end of the fourth part 64, and an E-ring 74 is fitted into this groove 641 as will be described later.

[0019] Figure 3(b) is a perspective view showing the one-way clutch attached to the first shaft. As shown in Figure 3(b), the one-way clutch 9 is formed in a cylindrical shape, and the second portion 62 of the first shaft 6 is press-fitted inside it. The lower end surface of the one-way clutch 9 faces the upper surface 612 of the first portion 61 of the first shaft 6 with a gap between them, but they may be in contact. On the other hand, the upper end of the one-way clutch 9 protrudes slightly above the second portion 62, but as shown in Figure 2, after assembly it is in contact with the lower end surface of the second portion 72 of the second shaft 7. The one-way clutch 9 is also formed of a magnetic material.

[0020] Figure 3(c) is a perspective view showing the one-way clutch with the second shaft portion attached. As shown in Figures 3(c) and 4, the second shaft portion 7 has a cylindrical first portion 71 and a second portion 72 connected to the upper end of the first portion 71. The lower end of the first portion 71 faces the upper surface 612 of the first portion 61 of the first shaft portion 6 with a small gap between them. The outer circumferential surface of the one-way clutch 9 is press-fitted into the inner wall surface of the first portion 71. The wall thickness of the first portion 71 is approximately the difference between the outer diameter of the first portion 61 of the first shaft portion 6 and the outer diameter of the one-way clutch 9. Therefore, the outer circumferential surface of the first portion 71 of the second shaft portion 7 and the outer circumferential surface of the first portion 61 of the first shaft portion 6 are approximately flush.

[0021] In this configuration, the one-way clutch 9 is housed between the first shaft portion 6 and the second shaft portion 7, and is configured so that it is not generally exposed to the outside of the shaft body 1.

[0022] The second part 72 is formed in a cylindrical shape with a larger diameter than the first part 71. The third part 63 and the fourth part 64 of the first shaft part 6 are inserted into the second part 72. The first bearing 73 is positioned between the fourth part 64 of the first shaft part 6 and the inner wall surface of the second part 72 of the second shaft part 7. Therefore, the first shaft part 6 is rotatable around its axis relative to the second shaft part 7 via the one-way clutch 9 and the first bearing 73. However, the one-way clutch 9 causes the first shaft part 6 and the second shaft part 7 to engage with each other during relative rotation in one direction, and to be able to rotate relative to each other during relative rotation in the other direction.

[0023] An annular notch 721 is formed at the upper end of the outer surface of the second part 72. In addition, a plurality of screw holes 722 are formed on the upper end surface of the second part 72.

[0024] Figure 3(d) is a perspective view showing the third shaft portion attached to the upper part of the second shaft portion. As shown in Figures 3(d) and 4, the third shaft portion 8 has a cylindrical first portion 81 and a second portion 82 connected to the upper end of the first portion 81. The outer diameter of the first portion 81 is approximately the same as the outer diameter of the second portion 72 of the second shaft portion 7. A circular recess 811 is formed in the center of the lower surface of the first portion 81, and the upper end of the fourth portion 64 of the first shaft portion 6 is inserted into this recess 811.

[0025] Furthermore, a notch 812 is formed on the lower part of the outer circumferential surface of the first part 81. This notch 812 and the notch 721 of the second shaft part 7 are flush, and the second bearing 83, which will be described later, is attached to this part. In addition, the first part 81 has a plurality of through holes 813 that extend in the vertical direction. The second shaft part 7 and the third shaft part 8 are connected by bolts inserted through these through holes 813 and screwed into the threaded holes 722 of the second shaft part 7.

[0026] The second part 82 is formed in a cylindrical shape with a smaller diameter than the first part 81, and is connected to an external device (not shown). This configuration allows rotational force from the external device to be applied to the shaft 1, causing the shaft 1 to rotate.

[0027] The first to third shaft portions 6 to 8 are formed of a non-magnetic material such as SUS304.

[0028] <1-2. Rotating plate> Figure 5 is a perspective view showing the shaft with the rotating plate, second bearing, and C-ring attached. As shown in Figure 5, the circular rotating plate 2 is fixed to the lower surface of the first portion 61 of the first shaft 6 by bolts. As a result, the rotating plate 2 and the first shaft 6 rotate together.

[0029] As shown in Figure 5, a second bearing 83 is fixed across the second shaft portion 7 and the third shaft portion 8. A C-ring 84 is also fixed to the upper surface of the second bearing 83. The outer edge of the C-ring 84 protrudes radially outward from the outer edge of the second bearing 83.

[0030] <1-3. First York> Figure 6 is a perspective view showing the first yoke positioned below the rotating plate. As shown in Figures 2 and 6, the first yoke 3 is formed of a cylindrical magnetic material and is positioned with a small gap between it and the rotating plate 2. The outer diameter of the first yoke 3 is larger than the outer diameter of the rotating plate 2. A through hole 31 is formed in the center of the first yoke 3, and a diaphragm (not shown) or the like can be placed in this through hole.

[0031] An annular groove 32 is formed on the upper part of the outer circumferential surface of the first yoke 3, which accommodates an O-ring 320, described later. In addition, a plurality of screw holes 33 are formed on the lower part of the outer circumferential surface of the first yoke 3 for fixing a cover member 5, described later.

[0032] <1-4. Second York> Figure 7 is a perspective view showing the second yoke positioned relative to Figure 6. As shown in Figures 2 and 7, the second yoke 4 is formed of a cylindrical magnetic material and has a through hole inside which a shaft is housed. This through hole has a first inner wall surface 41, a second inner wall surface 42, and a third inner wall surface 43 arranged from bottom to top. A first step portion 44 is formed between the first inner wall surface 41 and the second inner wall surface 42, and a second step portion 45 is formed between the second inner wall surface 42 and the third inner wall surface 43.

[0033] The first inner wall surface accommodates the first portion of the first shaft and the first portion of the second shaft, with a gap formed between them. The aforementioned X-ring 65 is positioned between the first portion 61 of the first shaft 6 and the first inner wall surface 41, allowing the shaft 1 to rotate inside the first inner wall surface 41.

[0034] The second inner wall surface 42 accommodates the second portion 72 of the second shaft portion 7, and a gap is formed between the two. The second bearing 83 is fixed to the third inner wall surface. Furthermore, an annular groove 431 is formed above the second bearing 83 on the third inner wall surface 43, and the aforementioned C-ring 84 is fitted into this groove 431. This restricts the downward movement of the shaft body 1 inside the second yoke.

[0035] The lower surface of the second yoke 4 is positioned opposite the rotating plate 2 with a small gap between them. The outer diameter of the second yoke 4 is larger than the outer diameter of the rotating plate 2. An annular groove 46 is formed on the lower part of the outer circumferential surface of the second yoke 4, which accommodates an O-ring 460, described later. In addition, on the outer circumferential surface of the second yoke 4, a number of screw holes 47 are formed slightly above the groove 46, in the lower part, for fixing the cover member 5, described later.

[0036] An annular groove 48 is formed inside the second yoke 4, extending axially around the shaft 1, and a coil 49 is wound around this groove 48. Current is input to this coil 49 from a control unit (not shown) located outside the magnetorheological fluid apparatus via a power supply connector (not shown) provided on the second yoke 4.

[0037] <1-5. Cover components> Figure 8 is a perspective view of the cover member. As shown in Figure 8, the cover member 5 has a cover body 51 formed in an annular shape from a plate material and an annular rib 52 formed on the inner wall surface of the cover body 51. As shown in Figure 2, the cover member 5 is configured to connect the outer circumferential surface of the first yoke 3 and the outer circumferential surface of the second yoke 4. At this time, the rib 52 of the cover member 5 is positioned between the first yoke 3 and the second yoke 4. That is, the vertical width of the rib 52 forms a gap between the first yoke 3 and the second yoke. Multiple first through holes 53 are formed at the lower part of the outer circumferential surface of the cover member 5, and screws inserted through these first through holes 53 are screwed into the screw holes 33 of the first yoke 3. In addition, multiple second through holes 54 are formed at the upper part of the outer circumferential surface of the cover member 5, and screws inserted through these second through holes 54 are screwed into the screw holes 47 of the second yoke.

[0038] Furthermore, a magnetorheological fluid is sealed in the space enclosed by the first yoke 3, the second yoke 4, and the cover member 5 (hereinafter referred to as the fluid space), and the rotating plate 2 rotates within the magnetorheological fluid. The magnetorheological fluid is a liquid in which magnetic particles are dispersed in a dispersion medium. As magnetic particles, for example, nano-sized metal particles (metal nanoparticles) can be used. There are no particular restrictions on the material of the metal particles, but soft magnetic materials are preferred. Examples of soft magnetic materials include alloys of iron, cobalt, nickel, and permalloy. The dispersion medium is not particularly limited, but one example is hydrophobic silicone oil. The amount of magnetic particles in the magnetorheological fluid can be, for example, 3 to 40 vol%. Various additives can also be added to the magnetorheological fluid to obtain desired properties.

[0039] <2. Assembly of the magnetorheological fluid apparatus> Next, we will describe an example of assembling a magnetorheological fluid apparatus configured as described above. (1) A one-way clutch 9 is press-fitted into the first portion 71 of the second shaft portion 7. (2) The second shaft portion 7, to which the one-way clutch 9 is attached, the second bearing 83, and the C-ring 84 are attached to the second yoke 4 from above. An O-ring 460 is attached to the groove 46 at the bottom of the second yoke 4, and the cover member 5 is then screwed on to cover the O-ring 460. The coil 49 and power supply connector are pre-attached to the second yoke 4. (3) Position the second yoke 4 so that its lower surface faces upward, and apply magnetorheological fluid to the lower surface of the second yoke 4. (4) The X-ring 65 and the rotating plate 2 are attached to the first shaft portion 6, and this is inserted into the second yoke 4. That is, the second portion 62 of the first shaft portion 6 is press-fitted into the one-way clutch 9. At this time, in order to create a gap between the lower end surface of the one-way clutch 9 and the upper surface 612 of the first shaft portion 6, and between the rotating body 2 and the second yoke 3, it is necessary not to insert the first shaft portion 6 too far into the second yoke 4. (5) The first bearing 73 is attached to the fourth part 64 of the first shaft portion 6 located within the second part 72 of the second shaft portion 7, and an E-ring 74 is attached to the groove 641 of the fourth part 64. Since the E-ring 74 is positioned on the first bearing 73, it acts as a retainer, preventing the first shaft portion 6 from detaching from the second shaft portion 7. (6) Apply magnetorheological fluid to the surface of the rotating plate 2 on the side facing the first yoke 3, insert the first yoke 3 with the O-ring attached into the cover member 5, and fasten it with screws. (7) Invert the assembly so that the second yoke 4 is positioned on the upper side, and secure the third shaft portion 8 to the second shaft portion 7 with bolts. (8) The through hole 31 of the first yoke 3 is closed with a diaphragm or the like. This completes the assembly of the magnetorheological fluid apparatus.

[0040] <3. Operation of magnetorheological fluid apparatus> In the magnetorheological fluid apparatus configured as described above, when an electric current is applied to the coil 49, a magnetic path is formed within the rotating plate 2, the first yoke 3, and the second yoke 4 along the direction indicated by the arrow P shown in Figure 9. This magnetic path penetrates the magnetorheological fluid interposed in the gap between the rotating plate 2 and the first yoke 3, and the magnetorheological fluid interposed in the gap between the rotating plate 2 and the second yoke 4. In this state, the behavior when a force is applied to the third shaft 8 in one direction around its axis and when it rotates in the opposite direction will be explained.

[0041] <3-1. Unidirectional rotation> (1) A force is applied to the third shaft portion 8 in one direction around the axis. (2) The third shaft portion 8 and the second shaft portion 7 connected thereto rotate in one direction. (3) The one-way clutch 9 connects the second shaft portion 7 and the first shaft portion 6, and the rotating plate 2 connected to the first shaft portion 6 also rotates in one direction. In other words, the shaft body 1 and the rotating plate 2 rotate together in one direction. (4) As the rotating plate 2 rotates in the magnetorheological fluid, viscosity (shear stress) is generated in the magnetorheological fluid in proportion to the strength of the magnetic field, and the torque transmitted between the rotating plate 2 and the yokes 3 and 4 increases in proportion to the strength of the magnetic field. In other words, the magnetorheological fluid generates a braking torque on the shaft 1.

[0042] <3-2. Rotation in other directions> (1) A force is applied to the third shaft portion 8 in a direction other than the axis. (2) The third shaft portion 8 and the second shaft portion 7 connected thereto rotate in opposite directions. (3) Due to the one-way clutch 9, rotation of the second shaft portion 7 in the other direction is not transmitted to the first shaft portion 6, so the second shaft portion 7 rotates freely relative to the first shaft portion 6. Consequently, the first shaft portion 6 does not rotate, and only the second shaft portion 7 and the third shaft portion 8 rotate together due to the force applied to the third shaft portion 8 in the other direction. (4) Since the first shaft portion 6 does not rotate, even if the torque transmitted between the rotating plate 2 and the yokes 3 and 4 by the magnetorheological fluid is large, it will not be transmitted from the first shaft portion 6 to the second shaft portion 7 and the third shaft portion 8 as a braking torque.

[0043] <4. Features> According to this embodiment, the following effects can be obtained.

[0044] (1) The one-way clutch 9 is housed between the first shaft portion 6 and the second shaft portion 7 and is configured so as not to be exposed to the outside of the shaft body 1. Therefore, even if a magnetic field is generated by energizing the coil 49, it is possible to suppress the concentration of magnetic flux on the one-way clutch 9. This prevents the one-way clutch 9 from being magnetized by the magnetic field or from having its engagement or free-spinning operation hindered. Thus, the operation of the one-way clutch 9 can be stabilized.

[0045] (2) The one-way clutch 9 is positioned between the first shaft portion 6 and the second shaft portion 7. Therefore, when the second shaft portion 7 rotates in one direction together with the third shaft portion 8, the first shaft portion 6 and the rotating plate 2 also rotate in one direction due to that rotation. On the other hand, when the second shaft portion 7 rotates in another direction together with the third shaft portion 8, the second shaft portion 7 rotates freely relative to the first shaft portion 6. This makes it possible to realize a magnetoviscous fluid device in which a braking torque is applied to the rotation of the second shaft portion 7 and the third shaft portion 8 in one direction, but no braking torque is applied to the rotation in the other direction.

[0046] (3) The one-way clutch 9 is positioned radially inward of the coil 49. Therefore, even with a configuration that includes the one-way clutch 9, it is easy to suppress the radial increase in size of the magnetorheological fluid device. Thus, it is easy to miniaturize the magnetorheological fluid device while providing unidirectionality with the one-way clutch 9.

[0047] <5. Variation> Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the invention. The following modifications can be combined as appropriate. Furthermore, the following modifications can be combined as appropriate with the above-described embodiment.

[0048] (1) In the above embodiment, the first shaft portion 6 corresponds to the second shaft body of the present invention, and the second shaft portion 7 and the third shaft portion 8 correspond to the first shaft body of the present invention. However, the configuration of each shaft body is not limited thereto. For example, at least one of the first shaft body and the second shaft body may be composed of a combination of multiple members or a single member. Furthermore, the shape of the first shaft body and the second shaft body is not limited to a cylindrical or cylindrical shape. As long as rotation in one direction can be transmitted via the one-way clutch 9, they may have a stepped shape, a shape with a cylindrical portion, or other rotating shaft shape.

[0049] (2) In the above embodiment, the one-way clutch 9 is housed between the first shaft portion 6 and the second shaft portion 7 and is configured not to be exposed to the outside of the shaft body 1 in general. However, the arrangement of the one-way clutch 9 is not limited to this. For example, the one-way clutch 9 may be covered at least on its radially inner and radially outer sides by the first shaft body and the second shaft body which are made of a non-magnetic material. Also, even if a part of the axial end of the one-way clutch 9 is exposed to the outside of the shaft body 1, it is sufficient as long as the influence of the magnetic field on the one-way clutch 9 can be suppressed. In other words, the one-way clutch 9 does not necessarily have to be completely covered by the first shaft portion (second shaft body) 6 and the second shaft portion (first shaft body) 7.

[0050] (3) In the second yoke 4, the corners formed on the surfaces facing the first shaft portion 6 and the second shaft portion 7 can be formed in an arc shape. For example, as shown in Figure 10, the corner where the first inner wall surface 41 and the first step portion 44 intersect, and the corner where the second inner wall surface 42 and the second step portion 45 intersect can be formed in an arc shape. This makes it easier to form a magnetic path that passes through the rotating plate 2 and the magnetorheological fluid around it, while suppressing magnetic flux leakage from the second yoke 4 to the one-way clutch 9. Therefore, it is possible to efficiently generate braking torque by the magnetorheological fluid while suppressing the influence of the magnetic field on the one-way clutch 9.

[0051] (4) In the above embodiment, the coil 49 is provided on the second yoke 4, the one-way clutch 9 is positioned radially inward of the coil 49, and the first yoke is positioned below the coil 49. However, the configuration and arrangement of the magnetic field generating unit are not limited thereto. For example, the coil 49 may be provided on the first yoke 3, the second yoke 4, the cover member 5, or other members connected thereto. Also, the one-way clutch 9 is not limited to radially inward of the coil 49, but may be positioned on one or the other axial side of the coil 49. Furthermore, in addition to the coil 49, the magnetic field generating unit may include a magnetic member for forming a magnetic path, a non-magnetic member for limiting magnetic flux, or a permanent magnet.

[0052] (5) The shape of the housing portion of the present invention is not particularly limited, and the shapes of the first yoke 3 and second yoke 4 constituting the housing portion shown in the above embodiment are just examples. Therefore, as long as it functions as a magnetorheological fluid device, the shape of the yoke as the housing portion is not particularly limited, and various configurations are possible, such as being composed of two or more members. The cover member 5 is provided as one of the components of the housing portion, and is a member whose function is to enclose the magnetorheological fluid, and the housing portion may be composed of other components. That is, it is sufficient that the housing portion has a yoke and is configured to enclose the magnetorheological fluid. Furthermore, the shape and position of the coil are not particularly limited as long as it functions as a magnetorheological fluid device, and various modifications are possible. Also, in the above embodiment, O-rings, C-rings, and X-rings are used as examples of sealing members, but the type, position, shape, etc. of the sealing member are not particularly limited, and may be used in configurations other than those shown in the above embodiment.

[0053] (6) The magnetorheological fluid apparatus according to the above embodiment may further include a reduction mechanism located outside the housing. The reduction mechanism may be connected, for example, to a third shaft 8 protruding from the second yoke (housing) 4, and configured to reduce the rotation of the third shaft 8 and output the result. In this case, the braking torque generated on the rotating plate 2 by the magnetorheological fluid can be amplified according to the reduction ratio of the reduction mechanism and acted on the output shaft of the reduction mechanism.

[0054] As a reduction mechanism, for example, a planetary gear mechanism, an eccentric planetary gear mechanism, a worm gear reduction mechanism, a bevel gear reduction mechanism, a spur gear reduction mechanism, a helical gear reduction mechanism, or a reduction mechanism combining these can be used. A planetary gear mechanism may include, for example, a sun gear connected to the third shaft portion 8, an internal gear arranged radially apart from the sun gear, planetary gears that mesh with the sun gear and the internal gear, and a carrier that rotatably supports the planetary gears. A worm gear reduction mechanism may include a worm connected to the third shaft portion 8 and a worm wheel that meshes with the worm. Furthermore, a bevel gear reduction mechanism may include a first bevel gear connected to the third shaft portion 8 and a second bevel gear that meshes with the first bevel gear.

[0055] With such a reduction mechanism, the rotation of the third shaft 8 can be reduced and output to the output shaft. Furthermore, the braking torque generated on the rotating plate 2 by the magnetorheological fluid can be amplified according to the reduction ratio of the reduction mechanism and applied to the output side. Therefore, a larger operating load or braking force can be applied to the output side without increasing the size of the magnetorheological fluid device itself.

[0056] When a magnetic field is applied to the magnetorheological fluid by energizing the coil 49, a braking torque is generated between the rotating plate 2 and the first yoke 3 and the second yoke 4. This braking torque is transmitted to the second shaft section 7 and the third shaft section 8 via the one-way clutch 9, and further acts on the output shaft of the reduction mechanism via the reduction mechanism. At this time, the braking torque acting on the output shaft can be increased by reducing the rotation speed due to the reduction mechanism. Therefore, a larger operating load or braking force can be applied to the output side without increasing the size of the magnetorheological fluid device itself.

[0057] On the other hand, when the second shaft portion 7 and the third shaft portion 8 rotate in a direction that does not transmit rotation to the rotating plate 2 side by the one-way clutch 9, even if a braking torque is generated by the magnetorheological fluid, it is possible to suppress that braking torque from acting on the output side of the reduction mechanism. Therefore, even in a configuration where the braking torque is amplified by the reduction mechanism, the one-way clutch 9 can be used to apply a large braking torque when rotating in a predetermined direction, and to make it easier to cause the output side to spin freely when rotating in the opposite direction. [Explanation of Symbols]

[0058] 1: Axis 3: York 1 (Detention Center) 4: Second York (Detention Center) 6: First shaft section (second shaft body) 7: Second shaft section (first shaft body) 8: Third shaft section (first shaft body) 9: One-way clutch 49: Coil

Claims

1. A first shaft body made of a non-magnetic material and rotatable around its axis, A second shaft, formed of a non-magnetic material and capable of relative rotation around an axis with respect to the first shaft, A rotating plate fixed to the second shaft body, A housing section that houses the first shaft, the second shaft, and the rotating plate, A magnetorheological fluid is sealed in the aforementioned housing and interposed between the rotating plate and the housing, A magnetic field generating unit that generates a magnetic field to be applied to the magnetoviscous fluid, A one-way clutch positioned between the first shaft and the second shaft, Equipped with, The one-way clutch is configured to transmit rotation of the first shaft in one direction to the second shaft, and not to transmit rotation of the first shaft in the other direction to the second shaft. The one-way clutch is covered by the first shaft and the second shaft. A magnetorheological fluid apparatus.

2. The one-way clutch is positioned radially between the first shaft and the second shaft. The magnetorheological fluid apparatus according to claim 1.

3. The one-way clutch is positioned radially inward of the coil of the magnetic field generating unit. The magnetorheological fluid apparatus according to claim 1 or 2.

4. The aforementioned housing section is A first yoke having a first opposing surface that faces one main surface of the rotating plate with a first gap in between, A second yoke having a second opposing surface that faces the other main surface of the rotating plate via a second gap, Equipped with, The magnetorheological fluid is filled into the first gap and the second gap. The aforementioned magnetic field generating unit is The device includes a coil, the first yoke, and the second yoke, and when the coil is energized, it forms a magnetic path passing through the first yoke, the second yoke, the rotating plate, and the magnetoviscous fluid. The magnetorheological fluid apparatus according to claim 1 or 2.

5. The housing further comprises a reduction mechanism located outside the aforementioned housing section, The reduction mechanism is connected to the first shaft body protruding from the housing and is configured to reduce the rotation of the first shaft body and output the result. The magnetorheological fluid apparatus according to claim 1 or 2.

6. In the aforementioned storage section, At least one corner formed on the surface facing the first shaft and the second shaft is formed in an arc shape. The magnetorheological fluid apparatus according to claim 1 or 2.

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