Coupling

Abstract

To provide a coupling capable of easily changing torsional rigidity.SOLUTION: A coupling 1 is equipped with a first joint portion 5 attached to a shaft 2 so as not to relatively rotate, a second joint portion 6 attached to a shaft 3 so as not to relatively rotate, and an intermediate portion 7 that is coupled between the first joint portion 5 and the second joint portion 6, and absorbs torsional vibrations. The coupling is further equipped with a magnetic field generating portion 9 that generates a magnetic field. The intermediate portion 7 includes a magnetic viscoelastic elastomer 7. Teh magnetic field generating portion 9 applies the magnetic field to the magnetic viscoelastic elastomer 7.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a coupling. [Background technology]

[0002] Couplings that connect shafts and transmit rotational power from a driving side to a driven side are known (see, for example, Patent Documents 1 to 4). The couplings disclosed in these documents include a driving side joint portion fixed to the driving side shaft, a driven side joint portion fixed to the driven side shaft, and an intermediate portion connected between these joint portions. In the couplings disclosed in Patent Documents 1 to 3, a leaf spring is included in the intermediate portion, and in the coupling disclosed in Patent Document 4, a rubber material is included in the intermediate portion.

[0003] The general roles of a coupling are (1) to transmit power from the driving side to the driven side, (2) to absorb installation errors between the driving and driven shafts, (3) to absorb vibrations on the driving side, and (4) to prevent heat from the driving motor or the like being transmitted to the driven side. In the couplings disclosed in Patent Documents 1 to 4, with regard to the role of (3) above, vibrations on the driving side are absorbed in the intermediate section. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2012-167743 A [Patent Document 2] JP 2002-372068 A [Patent Document 3] Japanese Patent Publication No. 155335 / 1983 [Patent Document 4] JP 2014-092168 A Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, the torsional vibration absorbed by the coupling can be suppressed by changing the torsional rigidity of the coupling, and the resonance point of the torsional vibration can also be changed.

[0006] However, in the couplings disclosed in Patent Documents 1 to 4, in order to change the torsional rigidity, it is necessary to replace the leaf spring or rubber material used in the middle part of the coupling with one having a different rigidity, or to replace the entire coupling with another coupling having a different torsional rigidity.

[0007] The present invention has been devised in view of the above circumstances, and an object of the present invention is to provide a coupling whose torsional rigidity can be easily changed. [Means for solving the problem]

[0008] A coupling according to a first aspect of the present invention includes a first joint part attached to one shaft so as to be non-rotatable relative to the other shaft, a second joint part attached to the other shaft so as to be non-rotatable relative to the other shaft, and an intermediate part connected between the first joint part and the second joint part and configured to absorb torsional vibrations, and further includes a magnetic field generating part that generates a magnetic field. The intermediate part includes a magnetorheological elastomer, and the magnetic field generating part applies a magnetic field to the magnetorheological elastomer.

[0009] A coupling having such a configuration makes it possible to easily change its torsional rigidity.

[0010] A coupling according to a second aspect of the present invention is the coupling according to the first aspect, wherein the magnetorheological elastomer is formed in a flat plate shape at least in a portion through which a magnetic path passes. Effect of the Invention

[0011] According to the present invention, it is possible to provide a coupling whose torsional rigidity can be easily changed. [Brief description of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view showing a coupling according to an embodiment of the present invention. [Diagram 2] FIG. 11 is a cross-sectional view showing a modified example of the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A coupling according to an embodiment of the present invention will now be described with reference to the drawings.

[0014] As shown in FIG. 1, the coupling 1 according to this embodiment is connected between a driving-side rotating shaft 2 and a driven-side rotating shaft 3, and includes a first joint portion 5, a second joint portion 6, an intermediate portion 7, and a magnetic field generating portion 9.

[0015] The first joint part 5 is attached to the drive-side rotating shaft 2 so as to be unable to rotate relative to the drive-side rotating shaft 2, and rotates integrally with the drive-side rotating shaft 2. As described below, the first joint part 5 also serves as a first inner yoke 15a of the magnetic field generating part 9. Therefore, it is preferable that the first joint part 5 is made of a magnetic material.

[0016] The second joint part 6 is attached to the driven-side rotating shaft 3 so as to be unable to rotate relative to the driven-side rotating shaft 3, and rotates integrally with the driven-side rotating shaft 3. As will be described later, the second joint part 6 also serves as a second inner yoke 15b of the magnetic field generating part 9. Therefore, it is preferable that the second joint part 6 is made of a magnetic material.

[0017] The first joint part 5 and the second joint part 6 have end faces that face each other in the axial direction. A minute gap 20 is formed between the end faces of the first joint part 5 and the second joint part 6, extending in the radial direction with a minute space in the axial direction.

[0018] The intermediate portion 7 is connected between the first joint portion 5 and the second joint portion 6. In this embodiment, the intermediate portion 7 is a magnetorheological elastomer 7 that is disposed in the minute gap 20 and formed into a flat plate that is circular when viewed in the axial direction. In this embodiment, the magnetorheological elastomer 7 is filled throughout the minute gap 20.

[0019] The magnetorheological elastomer 7 has a matrix elastomer (elastic material) with viscoelasticity as a matrix, and a large number of conductive magnetic particles dispersed in the matrix elastomer. Since the conductive magnetic particles are dispersed in the matrix elastomer, the magnetorheological elastomer 7 reversibly changes its mechanical properties such as elastic modulus and damping characteristics in response to the strength of the applied magnetic field.

[0020] Examples of materials constituting the substrate elastomer include known polymeric materials that have viscoelasticity at room temperature, such as ultrasoft urethane resin, ethylene-propylene rubber, and silicone rubber.

[0021] The magnetic particles have the property of being magnetically polarized by the action of a magnetic field. The magnetic particles preferably have high magnetic permeability and small residual magnetization. Examples of materials constituting the magnetic particles include iron, iron nitride, iron carbide, carbonyl iron, magnetic iron oxides, ferrites, nickel, cobalt, or cobalt-iron alloys, magnetite, goethite, and the like. The shape of the magnetic particles is not particularly limited, and may be, for example, spherical, needle-shaped, or tabular. The particle size of the magnetic particles is not particularly limited, and may be, for example, about 0.01 μm to 500 μm.

[0022] When the strength of the applied magnetic field is sufficiently low, the magnetic particles behave in such a way that the mutual interaction between them is negligibly small, and as the strength of the applied magnetic field increases, the magnetic interaction increases the mutual attractive force acting on them. This behavior of the magnetic particles makes it possible to change the elastic modulus and rigidity (including torsional rigidity) of the magnetorheological elastomer. The ratio of the magnetic particles to the matrix elastomer can be set arbitrarily, and may be, for example, about 5% to 85% in volume fraction. The dispersion state of the magnetic particles in the matrix elastomer may be uniform in each part of the matrix elastomer, or a density difference may be provided in some parts.

[0023] One end of the magnetorheological elastomer 7 is fixed to the first joint 5, and the other end is fixed to the second joint 6. As a result, when a displacement occurs in a torsional direction between the driving-side rotating shaft 2 and the driven-side rotating shaft 3, the magnetorheological elastomer 7 elastically deforms in the torsional direction.

[0024] The magnetic field generating unit 9 generates a magnetic field and applies the magnetic field to the intermediate portion 7 (the magnetorheological elastomer 7). In this embodiment, the magnetic field generating unit 9 includes a yoke 15 and a coil 16.

[0025] In this embodiment, the yoke 15 is made up of a first inner yoke 15a, a second inner yoke 15b, and an outer yoke 15c. All of the members constituting the yoke 15 are naturally made of magnetic material.

[0026] In this embodiment, the first joint part 5 also serves as the first inner yoke 15a, and the second joint part 6 also serves as the second inner yoke 15b.

[0027] One end face of the outer yoke 15c faces the radially outer surface of the first inner yoke 15a via a small gap, and the other end face faces the radially outer surface of the second inner yoke 15b via a small gap. In this embodiment, the outer yoke 15c is formed in an overall annular shape and has a substantially C-shaped cross section.

[0028] Bearing housing members 17 are fixed to both axial sides of the outer yoke 15c. A bearing 18 is interposed between one bearing housing member 17 and the first joint part 5, and a bearing 18 is interposed between the other bearing housing member 17 and the second joint part 6. Therefore, the first joint part 5, the second joint part 6, and the intermediate part 7 are rotatable with respect to the outer yoke 15c and the coil 16. The bearing housing member 17 is preferably made of a non-magnetic material.

[0029] The coil 16 is wound on the inside of the outer yoke 15c. A current of a desired value can be supplied to the coil 16 from a power supply unit 21. When a current is supplied to the coil 16, the coil 16 can form a magnetic path within the yoke 15. When a magnetic path is formed within the yoke 15, a magnetic field is applied to the intermediate portion 7 (magnetic viscoelastic elastomer 7) sandwiched between the first inner yoke 15a (first joint portion 5) and the second inner yoke 15b (second joint portion 6).

[0030] In the coupling 1 having the above-mentioned configuration, when a current is applied to the coil 16 by the power supply unit 21, a magnetic path is formed in the yoke 15 along the direction of the arrow P in Fig. 1, for example. In particular, a magnetic path is formed that penetrates the magnetorheological elastomer 7 disposed in the minute gap 20 between the first joint part 5 and the second joint part 6, and the magnetorheological elastomer 7 exhibits a torsional rigidity whose magnitude corresponds to the strength of the applied magnetic field. Then, by changing the value of the current applied to the coil 16, the torsional rigidity of the magnetorheological elastomer 7 can be changed, and therefore the torsional rigidity of the coupling 1 can also be changed.

[0031] As described above, according to the coupling 1 of this embodiment, the torsional rigidity of the coupling 1 can be changed simply by changing the value of the current applied to the coil 16. Therefore, the torsional vibration input to the coupling 1 can be easily suppressed, and the resonance point of the torsional vibration can also be easily changed.

[0032] The present inventors have also invented a coupling that uses a magnetorheological fluid instead of the magnetorheological elastomer 7. The coupling 1 according to this embodiment that uses the magnetorheological elastomer 7 has the advantage that there is absolutely no possibility of fluid leakage compared to one that uses a magnetorheological fluid.

[0033] Furthermore, in the coupling 1 having the above-mentioned configuration, the magnetorheological elastomer 7 is formed in a flat plate shape, and therefore can receive the torsion associated with the relative rotation between the first joint part 5 and the second joint part 6 as a circumferential shear force, and the torsional rigidity is appropriately controlled by the magnetic field generating part 9, thereby effectively suppressing the torsional vibration input to the coupling 1.

[0034] <Modification> In the above-described embodiment of the present invention, the entire intermediate portion is made of a magnetorheological elastomer, but a part of the intermediate portion may be made of a magnetorheological elastomer and the other portion of the intermediate portion may be made of an elastically deformable material. Note that the same reference numerals may be used to designate the same members as those described in the above-described embodiment, and descriptions thereof may be omitted.

[0035] For example, as shown in FIG. 2, the intermediate portion 7A is composed of a central rubber 7Aa provided across the first joint portion 5 and the second joint portion 6 on the axis N, an annular rubber 7Ab provided across the first joint portion 5 and the second joint portion 6 in the vicinity of the side surfaces of the first joint portion 5 and the second joint portion 6, and a magnetorheological elastomer 7Ac interposed in a minute gap 20 formed between the first joint portion 5 and the second joint portion 6 in the radial direction between the central rubber 7Aa and the annular rubber 7Ab. One of the central rubber 7Aa, the annular rubber 7Ab, and the magnetorheological elastomer 7Ac is fixed to the first joint portion 5, and the other is fixed to the second joint portion 6. When a displacement occurs in a torsional direction between the driving side rotating shaft 2 and the driven side rotating shaft 3, each of the central rubber 7Aa, the annular rubber 7Ab, and the magnetorheological elastomer 7Ac elastically deforms in the torsional direction. The central rubber 7Aa and the annular rubber 7Ab each have a constant elastic modulus, and when torsional vibration is input from the driving-side rotating shaft 2 or the driven-side rotating shaft 3, they absorb the torsional vibration while elastically deforming in the torsional direction.

[0036] The magnetic field generating unit 9A generates a magnetic field and applies the magnetic field to the magnetorheological elastomer 7Ac in the intermediate portion 7A.

[0037] In the coupling 1A having such a configuration, a magnetic path is also formed that penetrates the magnetorheological elastomer 7Ac disposed in the minute gap 20, and the magnetorheological elastomer 7Ac exhibits a torsional rigidity whose magnitude corresponds to the strength of the applied magnetic field. By changing the value of the current applied to the coil 16, the torsional rigidity of the magnetorheological elastomer 7Ac can be changed, and therefore the torsional rigidity of the coupling 1 can also be changed.

[0038] Therefore, according to the coupling 1A of this modification, the torsional rigidity of the coupling 1A can be changed simply by changing the value of the current applied to the coil 16. Therefore, the torsional vibration input to the coupling 1A can be easily suppressed, and the resonance point of the torsional vibration can also be easily changed.

[0039] In the above-described embodiment of the present invention, the magnetorheological elastomer constituting the intermediate portion is entirely formed in a flat plate shape, but at least the portion of the magnetorheological elastomer through which the magnetic path passes may be formed in a flat plate shape. Even in this case, the portion of the magnetorheological elastomer can receive the torsion caused by the relative rotation between the first joint part 5 and the second joint part 6 as a circumferential shear force, and the torsional rigidity is appropriately controlled by the magnetic field generating part 9, so that the torsional vibration input to the coupling 1 can be effectively suppressed. [Industrial Applicability]

[0040] The present invention can be applied, for example, to a coupling for connecting shafts. [Explanation of symbols]

[0041] 1,1A coupling 5 First joint 6 Second joint 7 Middle part (Magnetic viscoelastic elastomer) 7A middle part 7Aa Center Rubber 7Ab Circular Rubber 7Ac Magnetorheological Elastomer 9,9A Magnetic field generating unit 15 York 15a 1st inner yoke 15b 2nd inner yoke 15c outer yoke 16 Coils 20 Small gap N axis

Claims

[Claim 1] A first joint portion that is attached to one of the shafts so as not to rotate relative to the one of the shafts; A second joint portion that is attached to the other shaft so as not to rotate relative to the other shaft; an intermediate portion connected between the first joint portion and the second joint portion and configured to absorb torsional vibration; A coupling comprising: Further comprising a magnetic field generating unit that generates a magnetic field, the intermediate portion includes a magnetorheological elastomer; The magnetic field generating unit applies a magnetic field to the magnetorheological elastomer, The magnetorheological elastomer is formed in a flat plate shape at least in a portion through which a magnetic path passes. A coupling characterized by:

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