Magnetorheological fluid device

Abstract

To provide a technique capable of reducing power consumption of a magnetic viscous fluid device in order to further improve performance of the magnetic viscous fluid device.SOLUTION: A magneto-rheological fluid device 1 includes a housing 10, a rotating shaft 20 having one end 21 disposed inside the housing 10 and the other end 22 disposed outside the housing 10, a bearing 25 that rotatably holds the rotating shaft 20, a rotor 30 having a flat bottom plate 31 to the center of which the one end 21 of the rotating shaft 20 is connected and a side plate 32 that rises from the outer edge of the bottom plate 31, a first iron core 41 disposed in a region surrounded by the side plate 32, and a second iron core 42 having a base 43 disposed outside the bottom plate 31 and a standing portion 44 disposed outside the side plate 32. The motor includes a stator 40 in which a gap where a magnetic viscous fluid can be arranged is formed between a first iron core 41 and a second iron core 42, and a rotor 30, and a coil 50 to which a current can be supplied, and the coil 50 is arranged so that a magnetic flux generated when the current is supplied passes through a standing part 44.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] A magnetorheological fluid device is known that controls the viscosity of a magnetorheological fluid (MR fluid) placed in a gap by adjusting the magnetic flux density of a magnetic field applied to the MR fluid. MR fluid, also known as a magnetorheological fluid, is a material in which magnetic particles, such as iron-based particles with a particle diameter of 1 to 20 μm, are contained in insulating oil. When no magnetic field is applied, the magnetic particles of the MR fluid flow freely, resulting in low viscosity. On the other hand, when a magnetic field is applied, the magnetic particles align along magnetic field lines, resulting in high viscosity. As described in Non-Patent Documents 1 to 4, magnetorheological fluid devices can control the viscosity of an MR fluid by adjusting the magnetic flux density of a magnetic field applied to the MR fluid, and therefore are expected to be applied to controllable brakes, clutches, and the like.

[0003] Various techniques for improving the performance of magnetorheological fluid devices are known (see, for example, Patent Document 1). In the technique described in Patent Document 1, a sphere is fitted into a recess formed in the center of a rotating disk so that part of the sphere protrudes from the recess, thereby enabling the separation distance between the disk and the surface facing the disk to be precisely defined. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-183846 [Non-patent literature]

[0005] [Non-Patent Document 1] "Evaluation of Force Presentation Performance of Delta-Type Haptic Device Using Twin-Drive MR Fluid Actuator" (Ikeda et al., Robotics and Mechatronics Conference 2022 in Sapporo) [Non-patent document 2] "Development of a Compact Magnetorheological Fluid Clutch for Human-Friendly Actuator" (Kikuchi et al., Advanced Robotics, Volume 24, Issue 10 (2010)) [Non-patent document 3] "Development of Virtual Reality Bike with Cylindrical MR Fluid Brake" (Kikuchi et al., proceedings of the 2012 IEEE International conference on Robotics and Biomimetics, December 11 - 14, 2012) [Non-patent document 4] "Design and Analysis of a Small-Scale Magnetorheological Brake" (Patric S. Wellborn et al., IEEE / ASME TRANSACTION ON MECHATRONICS, VOL.27, NO. 5, OCTOBER 2022) Summary of the Invention [Problem to be solved by the invention]

[0006] The application of magnetorheological fluid devices to gripper-type haptic devices used at the hands of remote surgery, etc. When applying a magnetorheological fluid device to a gripper-type haptic device, it is desirable for the magnetorheological fluid device to be small and lightweight while maintaining high torque.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a magnetorheological fluid device that can be made smaller and lighter while maintaining high torque. [Means for solving the problem]

[0008] The magnetorheological fluid device of the present invention comprises a housing, a rotating shaft with one end located inside the housing and the other end located outside the housing, bearings that rotatably hold the rotating shaft, a rotor having a flat bottom plate portion to the center of which one end of the rotating shaft is connected, and side plate portions that stand up from the outer edge of the bottom plate portion, a stator having a first iron core located in an area surrounded by the side plate portions, and a second iron core having a base portion located outside the bottom plate portion and an upright portion located outside the side plate portions, and in which a gap is formed between the first iron core and the second iron core and the rotor in which a magnetorheological fluid can be placed, and a coil to which electric current can be supplied, the coil being positioned so that the magnetic flux generated when electric current is supplied passes through the side plate portions.

[0009] In the magnetorheological fluid device according to the present invention, the coil is preferably disposed in a region surrounded by the side plate portion.

[0010] In the magnetorheological fluid device according to the present invention, the distance between the coil and the side plate portion is preferably shorter than the distance between the coil and the rotation shaft.

[0011] In addition, in the magnetorheological fluid device of the present invention, it is preferable that the magnetic flux includes a first magnetic flux passing through the first iron core, the bottom plate portion, and the base portion, and a second magnetic flux passing through the first iron core, the bottom plate portion, the base portion, the upright portion, and the side plate portion.

[0012] In the magnetorheological fluid device according to the present invention, the bottom plate portion preferably has a circulation hole formed at a position facing the coil for circulating the magnetorheological fluid. [Effects of the Invention]

[0013] According to the present invention, the magnetorheological fluid device can be made smaller and lighter while maintaining high torque. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a front perspective view of a magnetorheological fluid device according to an embodiment. [Figure 2] FIG. 2 is a rear perspective view of the magnetorheological fluid device shown in FIG. [Figure 3] 2 is a cross-sectional view of the magnetorheological fluid device shown in FIG. 1 taken along line AA′. FIG. [Figure 4] 4(a) is a perspective view (part 1) of the rotating shaft shown in FIG. 3, and FIG. 4(b) is a perspective view (part 2) of the rotating shaft shown in FIG. [Figure 5] 4(a) is a perspective view (part 1) of the rotor shown in FIG. 3, and FIG. 4(b) is a perspective view (part 2) of the rotor shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0015] The magnetorheological fluid device according to the present invention will be described below with reference to the drawings. However, it should be noted that the technical scope of the present invention is not limited to the embodiments described therein, but extends to the inventions set forth in the claims and their equivalents.

[0016] FIG. 1 is a front perspective view of the magnetorheological fluid device according to the first embodiment, FIG. 2 is a rear perspective view of the magnetorheological fluid device shown in FIG. 1, and FIG. 3 is a cross-sectional view of the magnetorheological fluid device shown in FIG. 1 along line AA'.

[0017] The magnetorheological fluid device 1 has a housing 10, a rotating shaft 20, a bearing 25, a rotor 30, a stator 40, and a coil 50, and by supplying current to the coil 50, the viscosity of the MR fluid 100 filled in the gap formed between the rotor 30 and the stator 40 is controlled.

[0018] The housing 10 has a substantially cylindrical shape and includes a first housing 11, a second housing 12, a third housing 13, a fastening member 14, a first cover member 15, a second cover member 16, and a third cover member 17. The first housing 11 to the third cover member 17 are formed of a non-magnetic material such as synthetic resin, aluminum, or stainless steel, and house a rotating shaft 20, a bearing 25, a rotor 30, a stator 40, and a coil 50. The first housing 11 has a circular planar shape and a through-hole formed in the center through which the rotating shaft 20 passes. The second housing 12 has a cylindrical shape and houses the rotor 30, the stator 40, and the coil 50. The third housing 13 has a circular planar shape and, together with the first housing 11 and the second housing 12, forms a space that houses the rotating shaft 20, the bearing 25, the rotor 30, the stator 40, and the coil 50. The fastening member 14 is a screw and is arranged inside a fastening hole formed in each of the first housing 11, the second housing 12, and the third housing 13, and is a fastening member that integrates the first housing 11, the second housing 12, and the third housing 13.

[0019] The first lid member 15, the second lid member 16, and the third lid member 17 are placed in insertion holes formed in the third housing 13, and are removed from the third housing 13 when the housing 10 is filled with the MR fluid 100. The first lid member 15 is inserted into an insertion hole formed in the center of one surface of the third housing 13, and the second lid member 16 and the third lid member 17 are inserted into a pair of insertion holes arranged on either side of the insertion hole into which the first lid member 15 is inserted. The insertion hole into which the first lid member 15 is inserted functions as an injection hole into which the MR fluid 100 is injected, and the second lid member 16 and the third lid member 17 function as air vent holes through which air is discharged when the MR fluid 100 is injected into the insertion hole into which the first lid member 15 is inserted.

[0020] FIG. 4(a) is a perspective view (part 1) of the rotating shaft 20, and FIG. 4(b) is a perspective view (part 2) of the rotating shaft 20. As shown in FIG.

[0021] The rotating shaft 20 is formed of a non-magnetic material such as synthetic resin, such as polyethylene, aluminum, or stainless steel, and has a generally rod-like shape. One end 21 of the rotating shaft 20 is disposed inside the housing 10, and the other end 22 of the rotating shaft 20 is disposed outside the housing 10. A rotor 30 is fitted to one end 21 of the rotating shaft 20. The rotor 30 rotates in response to the rotation of the rotating shaft 20. The rotating shaft 20 is fixed to the housing 10 via a sealant 23 that seals the MR fluid 100 and a fixing member 24 that fixes the sealant 23. The sealant 23 and the fixing member 24 are formed of a non-magnetic material. The sealant 23 is a lip-type liquid seal that prevents the MR fluid 100 from creeping up the side surface of the rotating shaft 20 and leaking out. The fixing member 24 is fixed to the first housing 11 by a fastening member 14 so as to press the sealant 23 against the side surface of the rotating shaft 20.

[0022] The bearing 25 is made of a non-magnetic material such as aluminum or stainless steel, and is fixed to the housing 10. The bearing 25 holds the rotating shaft 20 rotatably.

[0023] FIG. 5(a) is a perspective view (part 1) of the rotor 30, and FIG. 5(b) is a perspective view (part 2) of the rotor 30. As shown in FIG.

[0024] The rotor 30 is formed from a thin plate of a non-magnetic material such as stainless steel or aluminum, and has a cup-like shape having a flat bottom plate portion 31 and side plate portions 32. The bottom plate portion 31 is disk-shaped, and has a fitting hole 33 formed in the center to fit over one end 21 of the rotating shaft 20, and fourteen circulation holes 34 formed in an annular shape at equal intervals for circulating the MR fluid. The circulation holes 34 formed in the bottom plate portion 31 are positioned opposite the coil 50. The side plate portions 32 are cylindrical, and are arranged to stand upright from the outer edge of the base in the normal direction of the bottom plate portion 31.

[0025] The stator 40 has a first iron core 41 and a second iron core 42. The first iron core 41 and the second iron core 42 are made of a magnetic material such as electromagnetic steel. The first iron core 41 has a cylindrical shape with an annular recess formed therein in which the coil 50 is disposed, and is disposed in an area surrounded by the side plate portion 32. The first iron core 41 has a guide hole formed therein that connects an insertion hole into which the first lid member 15 is inserted and a surface opposite to the surface facing the insertion hole into which the first lid member 15 is inserted. The guide hole formed in the first iron core 41 guides the MR fluid 100 injected through the insertion hole into which the first lid member 15 is inserted to the surface opposite to the surface facing the insertion hole into which the first lid member 15 is inserted.

[0026] The second core 42 has a base portion 43 arranged outside the bottom plate portion 31 of the rotor 30, and an upright portion 44 arranged outside the side plate portion 32 of the rotor 30. The base portion 43 has a circular planar shape, a through-hole through which the base portion 43 passes is formed in the center, and is arranged so that one surface faces the bottom plate portion 31 of the rotor 30 and the other surface faces the first housing 11 and the fixed member 24. The upright portion 44 has a cylindrical shape that rises from the outer edge of the base portion 43 in the normal direction of the base portion 43, and is arranged so that its inner surface faces the outer surfaces of the side plate portions 32 of the rotor 30 and its outer surface faces the inner surface of the second housing 12.

[0027] A gap is formed between the rotor 30 and the first and second iron cores 41 and 42, and the rotor 30, in which the rotor 30 and the MR fluid 100 can be placed. The width of the gap formed between the rotor 30 and the first and second iron cores 41 and 42 is determined by precision balls 26 that are arranged to engage with recesses formed at one end 21 of the rotating shaft 20 and at the center of the first iron core 41. The precision balls 26 are made of a non-magnetic material with high rigidity, such as aluminum or stainless steel, and determine the width of the gap formed between the rotor 30 and the first and second iron cores 41 and 42, and also function as bearings.

[0028] The coil 50 has an annular shape and is disposed in a recess formed in the first iron core 41, thereby being disposed in an area surrounded by the side plate portion 32 of the rotor 30, and can be supplied with current from a current source (not shown). The coil 50 is formed by winding a conductor such as a copper wire a predetermined number of times, such as 100 turns. The coil 50 is disposed so that magnetic flux generated when current is supplied from an external current source (not shown) passes through the upright portion 44 of the second iron core 42. Specifically, the coil 50 is disposed so that the distance between the coil 50 and the side plate portion 32 of the rotor 30 is shorter than the distance between the coil 50 and the rotating shaft 20.

[0029] The magnetic flux generated when current is supplied to coil 50 includes first magnetic flux 51 and second magnetic flux 52. First magnetic flux 51 forms a magnetic circuit that passes through first core 41, bottom plate 31 of rotor 30, base 43 of second core 42, and bottom plate 31 of rotor 30 in that order, and returns to first core 41. Second magnetic flux 52 passes through first core 41, bottom plate 31 of rotor 30, base 43 of second core 42, upright portion 44 of second core 42, and side plate 32 of rotor 30 in that order, and forms a magnetic circuit that returns to first core 41.

[0030] In the magnetorheological fluid device 1, the coil 50 is arranged so that the second magnetic flux 52 passes through the upright portion 44 of the second iron core 42, and therefore it is possible to control the viscosity of the MR fluid 100 around the side plate portion 32 of the rotor 30 that is arranged between the first iron core 41 and the upright portion 44. Because the magnetorheological fluid device 1 is able to control the viscosity of the MR fluid 100 around the side plate portion 32 of the rotor 30, it is possible to achieve miniaturization and weight reduction while maintaining high torque.

[0031] Specifically, when the thin plate forming the rotor 30 is 0.2 mm thick, the weight of the magnetorheological fluid device 1 can be kept to 60 g or less, and the torque when a current of 1 An is supplied to the coil 50 can be set to 0.27 Nm. The weight of a conventional magnetorheological fluid device and the torque when a current of 1 An is supplied to the coil 50 are 106 g and 0.26 Nm, respectively, so the weight of the magnetorheological fluid device 1 is 40% or more lighter than a conventional magnetorheological fluid device with a similar torque.

[0032] Furthermore, in the magnetorheological fluid device 1, the rotor 30 is formed from a thin plate of a non-magnetic material such as aluminum, which allows for a reduction in the weight of the rotor 30. By reducing the weight of the rotor 30, the magnetorheological fluid device 1 can reduce the rotational inertia of the rotor 30 and achieve high torque.

[0033] Furthermore, in the magnetorheological fluid device 1, the rotor 30 is disposed in the gap formed between the first iron core 41 and the second iron core 42 and the rotor 30, and therefore it is possible to control the viscosity of the MR fluid 100 around the bottom plate 31 in addition to the side plate 32. Since the magnetorheological fluid device 1 controls the viscosity of the MR fluid 100 around the bottom plate 31 in addition to the side plate 32, it is possible to achieve a higher torque than when the viscosity of the MR fluid 100 around only the side plate 32 is controlled.

[0034] Furthermore, the magnetorheological fluid device 1 can be made smaller by arranging the coil 50 in an area surrounded by the side plate portions 32 of the rotor 30. In the magnetorheological fluid device 1, by forming the second iron core 42 to have a base portion 43 and an upright portion 44, it is possible to generate the second magnetic flux 52 so as to form a magnetic circuit that passes through the upright portions 44 of the second iron core 42 via the base portion 43 and the upright portions 44. In the magnetorheological fluid device 1, by forming the second iron core 42 to have the base portion 43 and the upright portions 44, it is possible to make the magnetorheological fluid device 1 smaller by arranging the coil 50 in an area surrounded by the side plate portions 32 of the rotor 30, and it is possible to generate the second magnetic flux 52 that passes through the upright portions 44, thereby achieving high torque.

[0035] Furthermore, in the magnetorheological fluid device 1, the circulation hole 34 formed in the bottom plate portion 31 is positioned to face the coil 50, so the first magnetic flux 51 and the second magnetic flux 52 do not pass through the circulation hole 34. In the magnetorheological fluid device 1, the first magnetic flux 51 and the second magnetic flux 52 do not pass through the circulation hole 34, and by controlling the viscosity of the MR fluid 100 around the bottom plate portion 31, high torque can be achieved.

[0036] Furthermore, in the magnetorheological fluid device 1, by arranging the coil 50 inside the stator 40, the circuit configuration of the current supply circuit that supplies current to the coil 50 can be made simpler than when the coil is arranged in the rotor.

[0037] The magnetorheological fluid device 1 has the characteristics of high torque, small size, and light weight, making it possible to use it as a haptic device capable of providing sensitive force interval feedback that can be used in remote surgery, virtual reality (VR), and game controllers.

[0038] In the magnetorheological fluid device 1, the coil 50 is disposed in an area surrounded by the side plate portion 32 of the rotor 30, but in the magnetorheological fluid device according to the embodiment, the coil may be disposed outside the rotor 30. Furthermore, in the magnetorheological fluid device 1, the coil 50 is disposed so that the distance between the coil 50 and the side plate portion 32 of the rotor 30 is shorter than the distance between the coil 50 and the rotating shaft 20. However, as long as the coil 50 is disposed so that magnetic flux generated by supplying current to the coil 50 passes through the side plate portion 32, the distance between the coil 50 and the side plate portion 32 of the rotor 30 may be longer than the distance between the coil 50 and the rotating shaft 20.

[0039] Furthermore, in the magnetorheological fluid device 1, a first magnetic flux 51 and a second magnetic flux 52 are generated when a current is supplied to the coil 50. However, in the magnetorheological fluid device, the coil 50 may be arranged so that a single magnetic flux passing through the side plate portion 32 is generated when a current is supplied to the coil 50. Furthermore, in the magnetorheological fluid device, the stator 40 and the coil 50 may be arranged so that another magnetic flux is generated in addition to the first magnetic flux 51 and the second magnetic flux 52.

[0040] In the magnetorheological fluid device 1, the rotating shaft 20 and the rotor 30 are connected by fitting one end 21 of the rotating shaft 20 into a fitting hole 33 formed in the rotor 30. However, in the magnetorheological fluid device according to the embodiment, the rotating shaft 20 and the rotor 30 may be connected via a connecting member such as an adhesive. [Explanation of symbols]

[0041] 1. Magnetorheological fluid device 10. Cabinet 20 Rotation axis 30 rotor 31 Bottom plate part 32 Side plate part 40 Stator 41 First iron core 42 Second iron core 43 Base 44 Standing part 50 coils 51 First magnetic flux 52 Second magnetic flux 100 MR fluid (Magnetic Rheological Fluid)

Claims

1. The housing and a rotating shaft having one end disposed inside the housing and the other end disposed outside the housing; a bearing that rotatably holds the rotary shaft; a rotor having a flat bottom plate portion connected to the center of one end of the rotary shaft, and side plate portions standing upright from the outer edge of the bottom plate portion; a stator including a first core disposed in an area surrounded by the side plate portions, and a second core having a base portion disposed outside the bottom plate portion and an upright portion disposed outside the side plate portions, wherein a gap is formed between the first core and the second core and the rotor, and a magnetorheological fluid can be disposed therein; a coil to which a current can be supplied, The coil is disposed so that magnetic flux generated when a current is supplied to the coil passes through the side plate portion.

2. The magnetorheological fluid device according to claim 1 , wherein the coil is disposed in an area surrounded by the side plate portion.

3. The magnetorheological fluid device according to claim 2 , wherein the distance between the coil and the side plate portion is shorter than the distance between the coil and the rotation shaft.

4. The magnetic flux is a first magnetic flux passing through the first iron core, the bottom plate portion, and the base portion; a second magnetic flux passing through the first iron core, the bottom plate portion, the base portion, the upright portion, and the side plate portion; The magnetorheological fluid device according to any one of claims 1 to 3, comprising:

5. 4. The magnetorheological fluid device according to claim 1, wherein the bottom plate portion has a circulation hole formed in a position facing the coil for circulating the magnetorheological fluid.

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