Magnetorheological Fluid Device

Abstract

To provide a magnetic viscous fluid device having a characteristic value that is less likely to be affected by a surrounding environmental temperature irrespective of types of a dispersion medium of magnetic viscosity fluid.SOLUTION: A magnetic viscous fluid device includes: a rotor 3; a yoke 11 having an opposite surface 11a opposite to the rotor 3 via a fine clearance 17; magnetic viscous fluid 5 interposed in the fine clearance 17; and magnetic path forming means 4 for forming a magnetic path that penetrates the fine clearance 17. The magnetic path forming means 4 includes a coil 13. The magnetic viscous fluid device further includes a temperature adjusting part 6 provided while coming into contact with the yoke 11 to heat the yoke 11 and not including a coil.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a magnetorheological fluid device in which a magnetorheological fluid is interposed between members that are arranged to be capable of rotating relative to one another, and the torque transmitted between the members can be changed by changing the strength of a magnetic field applied to the magnetorheological fluid. [Background technology]

[0002] This type of magnetorheological fluid device is disclosed, for example, in Patent Documents 1 and 2. The magnetorheological fluid device disclosed in these documents has a magnetorheological fluid interposed between a disk and a casing, and can change the torque transmitted between the disk and the casing by changing the strength of the magnetic field applied to the magnetorheological fluid. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-011788 A [Patent Document 2] JP 2019-032050 A Summary of the Invention [Problem to be solved by the invention]

[0004] The viscosity of the dispersion medium (oil) of the magnetorheological fluid sealed in the magnetorheological fluid device depends on temperature. Therefore, the viscosity of the magnetorheological fluid changes depending on the heat generated by the coil for generating the magnetic field and the surrounding environmental temperature. As a result, the characteristic values ​​of the magnetorheological fluid device (for example, the rotational resistance generated when a certain current is applied to the coil) are also affected.

[0005] It is possible to suppress changes in the characteristic values ​​of a magnetorheological fluid device caused by changes in the environmental temperature, etc., by using a dispersion medium that has little change in viscosity over a wide temperature range, or by adding additives to the dispersion medium. However, the use of such dispersion medium or additives may have adverse effects on the magnetorheological fluid device (for example, a decrease in the durability of the magnetorheological fluid device).

[0006] SUMMARY OF THE PRESENTLY PREFERRED EMBODIMENTS An object of the present invention is to provide a magnetorheological fluid device whose characteristic values ​​are not easily affected by the surrounding environmental temperature, etc., regardless of the type of dispersion medium of the magnetorheological fluid used in the magnetorheological fluid device. [Means for solving the problem]

[0007] A magnetorheological fluid device according to a first aspect of the present invention includes a rotor, a yoke having a facing surface facing the rotor via a minute gap, and a magnetorheological fluid present in the minute gap; The magnetic flux collector further includes a temperature adjusting unit that is provided in contact with the yoke and that heats or cools the yoke.

[0008] According to a magnetorheological fluid device having such a configuration, the characteristic values ​​are less susceptible to the effects of the ambient temperature and the like, regardless of the type of dispersion medium of the magnetorheological fluid used in the magnetorheological fluid device.

[0009] A magnetorheological fluid device according to a second aspect of the present invention is a magnetorheological fluid device according to the first aspect, wherein the opposing surface of the yoke faces one surface of the rotor via a small gap, and the temperature control unit is provided in contact with the side of the yoke opposite the opposing surface and heats or cools the yoke.

[0010] A magnetorheological fluid device according to a third aspect of the present invention is the magnetorheological fluid device according to the first or second aspect, wherein the temperature adjustment unit has a shape and size to cover the rotor when viewed from the direction of the rotational axis of the rotor.

[0011] A magnetorheological fluid device according to a fourth aspect of the present invention is the magnetorheological fluid device according to any one of the first to third aspects, wherein the temperature adjustment section is a Peltier element.

[0012] A magnetorheological fluid device according to a fifth aspect of the present invention is the magnetorheological fluid device according to the first to fourth aspects, further comprising a temperature detection unit that detects the temperature of the magnetorheological fluid or the temperature of a part whose temperature changes in response to a change in temperature of the magnetorheological fluid, and a control unit that controls the temperature adjustment unit based on the temperature detected by the temperature detection unit.

[0013] A magnetorheological fluid device according to a sixth aspect of the present invention is a magnetorheological fluid device according to any one of the first to fourth aspects, wherein the magnetic path forming means includes a coil, and is provided with a resistance value detection unit that detects a current resistance value of the coil, and a control unit that controls the temperature adjustment unit based on the current resistance value detected by the resistance value detection unit.

[0014] A magnetorheological fluid device according to a seventh aspect of the present invention is the magnetorheological fluid device according to any one of the first to sixth aspects, wherein the temperature adjustment part is detachably provided on a side of the yoke opposite to the opposing surface. Effect of the Invention

[0015] According to the magnetorheological fluid device of the present invention, the characteristic values ​​are less susceptible to the effects of the surrounding environmental temperature and the like, regardless of the type of dispersion medium of the magnetorheological fluid. [Brief description of the drawings]

[0016] [Figure 1] 1 is a cross-sectional view showing a magnetorheological fluid device according to a first embodiment. [Diagram 2] FIG. 4 is a cross-sectional view showing a magnetorheological fluid device according to a modified example of the first embodiment. [Diagram 3] FIG. 4 is a cross-sectional view showing a magnetorheological fluid device according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] -First embodiment- A magnetorheological fluid device according to a first embodiment of the present invention will be described below with reference to the drawings. As shown in Fig. 1, the magnetorheological fluid device 1 according to this embodiment includes a rotating shaft 2, a rotor 3, a magnetic path forming means 4, a magnetorheological fluid 5, a temperature adjustment unit 6, a temperature detection unit 7, a control unit 8, etc.

[0018] The rotating shaft 2 is rotatably supported by a bearing 10, and one end of the rotating shaft 2 is connected to the center of the rotor 3.

[0019] The rotor 3 is provided so as to rotate integrally with the rotating shaft 2. In this embodiment, the rotor 3 is formed in a disk shape. The rotor 3 is desirably made of a magnetic material.

[0020] The magnetic path forming means 4 is configured using a first yoke 11, a second yoke 12, a coil 13, and the like.

[0021] The first yoke 11 has an opposing surface 11a that faces one surface 3a of the rotor 3. A small gap 17 is formed between the one surface 3a of the rotor 3 and the opposing surface 11a of the first yoke 11. In this embodiment, the first yoke 11 has a circular contour when viewed from the axial direction. A surface 11b (hereinafter also referred to as the "outer surface 11b") of the first yoke 11 opposite to the opposing surface 11a is formed flat. A space 11c for arranging the coil 13 is formed on the outer periphery of the first yoke 11.

[0022] The second yoke 12 has an opposing surface 12a that faces the other surface 3b of the rotor 3. A minute gap 18 is also formed between the other surface 3b of the rotor 3 and the opposing surface 12a of the second yoke 12. In this embodiment, the second yoke 12 also has a circular contour when viewed from the axial direction. An arrangement space 12c for the coil 13 is formed on the outer periphery side of the second yoke 12. As shown in FIG. 1, the outer periphery 12d of the second yoke 12 is connected to the outer periphery 11d of the first yoke 11. In addition, a shaft hole 12e, a bearing housing 12f, and an annular groove 12g are formed on the inside of the second yoke 12. The rotating shaft 2 is inserted into the shaft hole 12e. A bearing 10 that supports the rotating shaft 2 is fitted into the bearing housing 12f. A seal member 19 is fitted into the annular groove 12g. The seal member 19 seals the gap between the rotating shaft 2 and the second yoke 12 so as to prevent the magnetorheological fluid 5 from leaking to the outside.

[0023] The coil 13 is provided so as to form a magnetic path that crosses the minute gaps 17 and 18 at right angles when a current is applied. That is, when a current is applied to the coil 13, a magnetic path is formed in the direction along the arrow P in FIG. 1. In this embodiment, the coil 13 is disposed in an annular shape between the first yoke 11 and the second yoke 12 on the outside of the rotor 3. A desired current is supplied to the coil 13 from a power supply device (not shown).

[0024] The magnetorheological fluid 5 is enclosed in an enclosed space 21 formed inside the first yoke 11 and the second yoke 12. In Fig. 1, the area shaded in gray represents the enclosed space 21 for the magnetorheological fluid 5. This magnetorheological fluid 5 is present in a minute gap 17 between one surface 3a of the rotor 3 and the opposing surface 11a, and in a minute gap 18 between the other surface 3b of the rotor 3 and the opposing surface 12a, and transmits torque therebetween according to its viscosity.

[0025] The magnetorheological fluid 5 is a liquid in which magnetic particles are dispersed in a dispersion medium. For example, nano-sized metal particles (metal nanoparticles) can be used as the magnetic particles. The magnetic particles are made of a magnetizable metal material, and although there is no particular limitation on the metal material, a soft magnetic material is preferable. Examples of the soft magnetic material include alloys such as iron, cobalt, nickel, and permalloy. The dispersion medium is not particularly limited, and a well-known dispersion medium generally used in magnetorheological fluids can be used.

[0026] The temperature adjustment unit 6 is provided in contact with the outer surface 11b of the first yoke 11, and heats or cools the first yoke 11. In this embodiment, a Peltier element is used as the temperature adjustment unit 6. In this embodiment, the surface of the temperature adjustment unit 6 on the first yoke 11 side is disposed parallel to the minute gap 17, as shown in FIG.

[0027] The temperature detection unit 7 is for detecting the temperature of the magnetorheological fluid 5, and is configured using, for example, a temperature sensor. As shown in Fig. 1, it is desirable that the temperature sensing unit 7a of the temperature sensor is disposed within the magnetorheological fluid 5. In the example shown in Fig. 1, the temperature sensing unit 7a is disposed outside the outer periphery of the rotor 3, on a surface along the opposing surface 11a of the first yoke 11.

[0028] In addition, a heat dissipation / absorption member 14 is provided on the surface 7b of the temperature adjustment unit 6 opposite to the magnetorheological fluid 5. When the temperature adjustment unit 6 side becomes relatively high temperature, the heat dissipation / absorption member 14 dissipates heat conducted from the temperature adjustment unit 6 to the outside, and when the temperature adjustment unit 6 side becomes relatively low temperature, the heat absorbed from the outside is conducted to the temperature adjustment unit 6 side. As the heat dissipation / absorption member 14, a material having excellent thermal conductivity such as a copper alloy or an aluminum alloy can be used. For example, a heat sink made of an aluminum alloy can be used. In this embodiment, the heat dissipation / absorption member 14 is fixed to the inside of an annular member 23 made of a non-magnetic material, and the annular member 23 is fixed to the first yoke 11 and the second yoke 12 by a fastener 22 (bolts or the like in this embodiment). The temperature adjustment unit 6 is fixed to the inside of the annular member 23 while being sandwiched between the heat dissipation / absorption member 14 and the first yoke 11. In this embodiment, the temperature adjustment section 6 , the heat dissipation / absorption member 14 and the member 23 are integral with one another, and are detachably attached to the first yoke 11 by a fastener 22 .

[0029] Moreover, the temperature adjustment unit 6 has a shape (circular shape) and a size sufficient to cover the rotor 3 when viewed from the direction of the rotation axis of the rotor 3.

[0030] The control unit 8 controls the current supplied to the temperature adjustment unit 6 based on the temperature of the magnetorheological fluid 5 detected by the temperature detection unit 7. Specifically, the control unit 8 switches the current supplied to the temperature adjustment unit 6 and the polarity of the current so that the temperature of the magnetorheological fluid 5 detected by the temperature detection unit 7 approaches a predetermined temperature. For example, when the temperature of the magnetorheological fluid 5 is higher (for example, 40°C) than a predetermined target temperature (for example, 20°C) by a predetermined temperature (for example, 1°C), the control unit 8 supplies a current to the temperature adjustment unit 6 so that the temperature adjustment unit 6 cools the first yoke 11 until the temperature falls within a predetermined range (for example, the target temperature ±0.5°C) with respect to the target temperature. On the other hand, when the temperature of the magnetorheological fluid 5 is lower (for example, -5°C) than the predetermined target temperature (for example, 20°C) by a predetermined temperature (for example, 1°C), the control unit 8 supplies a current to the temperature adjustment unit 6 so that the temperature adjustment unit 6 heats the first yoke 11 until the temperature rises within a predetermined range (for example, the target temperature ±0.5°C) with respect to the target temperature. The control unit 8 may be configured using a microcomputer or the like, or may be configured using an electronic circuit that does not include a microcomputer.

[0031] According to the magnetorheological fluid device 1 described above, it is possible to maintain the temperature of the magnetorheological fluid 5 at a predetermined preferred temperature. Therefore, regardless of the type of dispersion medium of the magnetorheological fluid used in the magnetorheological fluid device 1, the characteristic values ​​(for example, the rotational resistance of the rotating shaft 2 generated when a predetermined current is applied to the coil 13) are unlikely to be affected by the surrounding environmental temperature, heat generation of the coil 13, etc.

[0032] In particular, since the temperature control unit 6 is located relatively close to the minute gap 17 between the rotor 3 and the first yoke 11, the magnetorheological fluid present in the minute gap 17 can be efficiently heated and cooled via the first yoke 11.

[0033] Furthermore, since the temperature adjustment unit 6 has a shape and size that covers the rotor 3 when viewed from the direction of the rotation axis of the rotor 3, the magnetorheological fluid present in the minute gap 17 can be heated or cooled uniformly and quickly throughout.

[0034] <Temperature detection unit variation 1> The temperature detection unit 7 detects the temperature of the magnetorheological fluid 5 using a temperature sensor, but the temperature of the magnetorheological fluid 5 and the temperatures of other parts (parts other than the magnetorheological fluid 5) in the magnetorheological fluid device 1 (for example, the temperatures of the first yoke 11, the second yoke 12, etc.) are linked to some extent. The temperature of the magnetorheological fluid 5 can also be estimated to some extent from the temperatures of the other parts. Therefore, instead of detecting the temperature of the magnetorheological fluid, the temperature of the other parts can be detected and the control unit 8 can control the current supplied to the temperature adjustment unit 6 based on the temperatures of the other parts detected by the temperature detection unit, so that the temperature of the magnetorheological fluid 5 can be maintained at a desired temperature to some extent. The same can be said about the second embodiment described later.

[0035] <Modification 2 of Temperature Detection Section> The temperature detection unit 7 detects the temperature of the magnetorheological fluid 5 using a temperature sensor, but instead of detecting the temperature of the magnetorheological fluid, a resistance value detection unit 26 that detects the current resistance value of the coil 13 may be provided as shown in FIG. 2, and the control unit 8 may control the current supplied to the temperature adjustment unit 6 based on the current resistance value detected by the resistance value detection unit 26. This allows the temperature of the magnetorheological fluid 5 to be maintained at a desired temperature to some extent. That is, the current resistance value of the coil 13 (the current resistance value of copper) increases as the temperature of the coil 13 increases and decreases as the temperature of the coil 13 decreases. Therefore, the temperature of the coil 13 can be estimated from the current resistance value of the coil 13, and the temperature of the magnetorheological fluid 5 can be estimated to some extent from the estimated temperature of the coil. This also applies to the second embodiment described later.

[0036] <Temperature control unit installation location> The location where the temperature adjustment unit 6 is attached in the first embodiment is one example of a location where the temperature of the magnetorheological fluid 5 can be easily maintained at a desired temperature. Even if the temperature adjustment unit 6 is installed in contact with the first yoke 11 or the second yoke 12 in a location other than the above, it is possible to maintain the temperature of the magnetorheological fluid 5 within a desired range to some extent. The same can be said about the second embodiment described later.

[0037] <Size of temperature control unit> The temperature adjustment unit 6 in the embodiment described above has a shape and size sufficient to cover the rotor 3, and therefore can uniformly and quickly heat and cool the magnetorheological fluid present in the minute gap 17 as a whole, but even if the temperature adjustment unit 6 does not have a size sufficient to cover the rotor 3, it is possible to maintain the temperature of the magnetorheological fluid 5 within a desired range to some extent. The same can be said about the second embodiment described later.

[0038] -Second embodiment- The magnetorheological fluid device 1B according to the second embodiment of the present invention will be described below. In the following description, when the functions of the components constituting each part are similar to those of the magnetorheological fluid device 1 described in the first embodiment, the same reference numerals as in the first embodiment will be used and the description will be omitted even if the shape is slightly different.

[0039] As shown in FIG. 3, a magnetorheological fluid device 1B according to the second embodiment includes a rotating shaft 2, a rotor 3, a magnetic path forming means 4, a magnetorheological fluid 5, a temperature adjustment unit 6, a temperature detection unit 7, a control unit 8, and the like.

[0040] The magnetic path forming means 4 is configured using a first yoke 11A, a second yoke 12A, a coil 13, etc. The magnetorheological fluid device 1B according to the second embodiment differs from the magnetorheological fluid device 1 according to the first embodiment mainly in the shapes, sizes, etc. of the first yoke 11A, the second yoke 12A, the rotor 3, the temperature adjustment unit 6, and the heat dissipation / absorption member 14.

[0041] That is, as shown in Fig. 3, the first yoke 11A is formed in a flat plate shape and has a diameter substantially equal to that of the rotor 3. The second yoke 12A is formed in a U-shaped cross section opening toward the rotor 3, and an opposing surface 12Aa opposing the other surface 3b of the rotor 3 is formed on the inside and outside of the coil 13. The temperature adjustment unit 6 has substantially the same shape and size as the first yoke 11A. The heat dissipation / absorption member 14 is provided so as to be in close contact with the entire temperature adjustment unit 6. The first yoke 11A, the second yoke 12A, and the temperature adjustment unit 6 are fitted and fixed in a cylindrical member 27 made of a non-magnetic material.

[0042] Further, the heat dissipating / absorbing member 14 is detachably fixed to the cylindrical member 27 by fasteners 22 such as bolts. Accordingly, the temperature adjustment section 6 is also detachably attached to the first yoke 11A and the like.

[0043] Coil 13 is provided so as to form a magnetic path that crosses minute gaps 17 and 18 at right angles when a current is applied. That is, when a current is applied to coil 13, a magnetic path is formed in the direction along arrow P in FIG. 3. In this embodiment, coil 13 is disposed in an annular groove of second yoke 12A. A desired current is supplied to coil 13 from a power supply device (not shown).

[0044] <Adding the temperature control unit later> In the first and second embodiments described above, the temperature adjustment unit 6 and the heat dissipation / absorption member 14 are detachably attached to the first yoke 11. However, even for magnetorheological fluid devices that do not have a temperature adjustment unit 6 and a heat dissipation / absorption member 14, as long as the shape and structure of the first yoke and the second yoke are similar to those of the first or second embodiment, it is possible to construct magnetorheological fluid devices 1, 1A, 1B with a temperature adjustment unit 6 as shown in Figures 1 to 3 by performing simple construction (for example, drilling screw holes for fasteners 22). [Industrial Applicability]

[0045] The present invention can be applied to a magnetorheological fluid device in which, for example, a magnetorheological fluid is interposed between components that are arranged to be rotatable relative to one another, and the torque transmitted between the components can be changed by changing the strength of the magnetic field applied to the magnetorheological fluid. [Explanation of symbols]

[0046] 1,1A,1B Magnetorheological fluid device 2 Rotation Axis 3 Rotor 3a One side of the rotor 3b The other side of the rotor 4 Magnetic path forming means 5. Magnetorheological fluid 6 Temperature control section 7 Temperature detection section 8. Control Unit 11 First York 11a Opposite side 11b External surface 12 Second York 12a Opposite side 13 Coil 14 Heat dissipation and absorption materials 17,18 Micro gap 19 Sealing material 22 Fixtures 26 Resistance detection section

Claims

1. A rotor; a yoke having a facing surface facing the rotor with a small gap therebetween; A magnetorheological fluid present in the minute gap; a magnetic path forming means for forming a magnetic path penetrating the minute gap; A magnetorheological fluid device comprising: The magnetic path forming means includes a coil, a temperature control unit that is provided in contact with the yoke and heats the yoke and does not include a coil; The magnetorheological fluid device according to claim 1, wherein the temperature adjustment section has a shape and size sufficient to cover the entire rotor when viewed from the direction of the rotation axis of the rotor.

2. A rotor; a yoke having a facing surface facing the rotor with a small gap therebetween; A magnetorheological fluid present in the minute gap; a magnetic path forming means for forming a magnetic path penetrating the minute gap; A magnetorheological fluid device comprising: The magnetic path forming means includes a coil, a temperature control unit that is provided in contact with the yoke and that heats and cools the yoke and does not include a coil; a temperature detection unit that detects a temperature of the magnetorheological fluid or a temperature of a portion that changes in temperature in accordance with a change in temperature of the magnetorheological fluid; a control unit that controls the temperature adjustment unit based on the temperature detected by the temperature detection unit so that the temperature detected by the temperature detection unit approaches a predetermined temperature and is maintained at the predetermined temperature; A magnetorheological fluid device comprising:

3. A rotor, a yoke having a facing surface facing the rotor with a small gap therebetween; A magnetorheological fluid present in the minute gap; a magnetic path forming means for forming a magnetic path penetrating the minute gap; A magnetorheological fluid device comprising: The magnetic path forming means includes a coil, a temperature control unit that is provided in contact with the yoke and that heats or cools the yoke and does not include a coil; a temperature detection unit that detects a temperature of the magnetorheological fluid or a temperature of a portion that changes in temperature in accordance with a change in temperature of the magnetorheological fluid; a control unit that controls the temperature adjustment unit based on the temperature detected by the temperature detection unit so that the temperature detected by the temperature detection unit approaches a predetermined temperature and is maintained at the predetermined temperature; Equipped with The magnetorheological fluid device according to claim 1, wherein the temperature adjustment section has a shape and size sufficient to cover the entire rotor when viewed from the direction of the rotation axis of the rotor.

4. The magnetorheological fluid device according to any one of claims 1 to 3, the opposing surface of the yoke faces one surface of the rotor via a minute gap, 2. A magnetorheological fluid device according to claim 1, wherein the temperature adjustment portion is provided in contact with a side of the yoke opposite to the opposing surface.

5. In the magnetorheological fluid device according to claim 2 or claim 4 depending on claim 2, The magnetorheological fluid device according to claim 1, wherein the temperature adjustment section has a shape and size sufficient to cover the entire rotor when viewed from the direction of the rotation axis of the rotor.

6. The magnetorheological fluid device according to any one of claims 1 to 5, The magnetorheological fluid device according to claim 1, wherein the temperature control unit is a Peltier element.

7. The magnetorheological fluid device according to any one of claims 1 to 6, The magnetorheological fluid device according to claim 1, wherein the temperature adjustment unit is detachably provided on a side of the yoke opposite the opposing surface.

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