JP2017089732A - Rotary resistance device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary resistance device capable of forming a magnetic path on a rotary shaft portion of a rotary body.SOLUTION: A rotary resistance device includes a supporting cylindrical portion 15 communicating the inside and outside of a case 3, a rotary shaft portion 21 disposed on a rotary body 5 and inserted to the supporting cylindrical portion 15, a pair of bearings 35a, 35b relatively rotatably supporting the rotary shaft portion 21 to the supporting cylindrical portion 15, and a spacer 37 disposed between the pair of bearings 35a, 35b. The spacer 37 includes a spacer body 37a with which outer races 35aa, 35ba of the pair of bearings 35a, 35b are kept into contact, and a projecting portion 37b projecting to a radial inner side from the spacer body 37a and defining a gap G capable of forming a magnetic path to a magnetic flux loop M between the rotary shaft portion 21 and the supporting cylindrical portion 15, with the rotary shaft portion 21.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a rotational resistance device such as a braking device using a magnetorheological fluid.

  As a conventional rotational resistance device of this type, for example, there is a braking device described in Patent Document 1.

  In this braking device, a magnetic viscous fluid is enclosed in a magnetic case and a rotating plate of the magnetic material is accommodated in a relatively rotatable manner, and the viscosity of the magnetic viscous fluid is changed between the case and the rotating plate by the magnetic flux of the electromagnetic coil. It is like that.

  Therefore, the braking device gives resistance to the relative rotation between the case and the rotating plate according to the viscosity of the magnetorheological fluid. For example, if one of the case and the rotating plate is fixed and used, a braking torque can be generated.

  The rotating plate is provided with a rotating shaft portion of a nonmagnetic material at the shaft center portion, and the rotating shaft portion is rotatably supported through the end wall of the case. Thereby, relative rotation with respect to the case of a rotating plate is implement | achieved.

  However, with such a structure, a magnetic path cannot be formed in the rotating shaft portion of the rotating plate. For this reason, it is necessary to increase the size to increase the braking torque, or to reduce the size, the braking torque decreases.

JP 2014-20539 A

  The problem to be solved is that a magnetic path could not be formed in the rotating shaft portion of the rotating body.

  According to the present invention, in order to form a magnetic path in the rotating shaft portion of the rotating body, a magnetorheological fluid is sealed in the case of the magnetic body and the rotating body of the magnetic body is accommodated so as to be relatively rotatable. A rotation resistance device that changes the viscosity of the magnetorheological fluid by the magnetic flux of the electromagnetic coil between the support cylinder portion provided in the case and communicating between the inside and the outside of the case; and the support cylinder provided in the rotating body A rotating shaft portion that is inserted through the portion, a pair of bearings that rotatably supports the rotating shaft portion relative to the support cylinder portion, and a spacer that is disposed between the pair of bearings, A spacer main body with which the outer races of the pair of bearings abut and a gap that protrudes radially inward from the spacer main body to form a magnetic path for the magnetic flux between the rotating shaft portion and the support cylinder portion. Further comprising a projecting portion for partitioning between the rotating shaft and the most main features.

  The rotation resistance device of the present invention can form a magnetic path in the rotating shaft portion of the rotating body via a spacer between the bearings.

It is sectional drawing of the braking device which is a rotation resistance apparatus. (Example 1) It is sectional drawing which shows the state which the side wall part of the case of the braking device of FIG. 1 elastically deformed. (Example 1) It is sectional drawing which expands and shows the spacer periphery in the braking device of FIG. (Example 1)

  For the purpose of forming a magnetic path in the rotating shaft of the rotating body, the rotating shaft is connected to the support cylinder that communicates the inside and outside of the case of the magnetic body that encloses the magnetorheological fluid and accommodates the rotating body of the magnetic body in a relatively rotatable manner. This is realized by providing a protrusion that protrudes inward in the radial direction in the spacer disposed between the bearings by supporting the part with a pair of bearings.

  Specifically, the spacer has a spacer main body with which an outer race of a pair of bearings abuts, and a clearance that protrudes radially inward from the spacer main body to form a magnetic path between the rotary shaft portion and the support cylinder portion. And a projecting portion partitioned between the two.

  The spacer body may have an annular shape formed along the inner periphery of the support cylinder portion, and the protrusion may have an annular shape formed along the inner periphery of the spacer body.

  The protruding portion may partition a gap between the protruding portion and the outer peripheral surface of the rotating shaft portion in the entire circumferential direction.

  The electromagnetic coil may be located on the outer periphery of the support cylinder portion.

[Brake device structure]
FIG. 1 is a cross-sectional view of the braking device. In the following description, the axial direction refers to the direction along the rotational axis of relative rotation, the radial direction refers to the rotational radius direction of relative rotation, and the circumferential direction refers to the relative rotational direction. In FIG. 1, the upper half and the lower half show cross sections at different positions in the circumferential direction.

  As shown in FIG. 1, the braking device 1 according to the first embodiment includes a case 3, a rotating body 5, and an electromagnetic coil 7. The braking device 1 uses one of the relatively rotatable case 3 and the rotating body 5 in a fixed manner, so that the resistance corresponding to the viscosity of the magnetorheological fluid F described later with respect to the relative rotation between the case 3 and the rotating body 5 is achieved. To generate a braking torque.

  If the brake device 1 is used by coupling the case 3 and the rotating body 5 together to a rotatable member, the braking device 1 can be used as a torque transmission device or the like by applying resistance to the relative rotation between the case 3 and the rotating body 5. It is.

  Therefore, the braking device 1 is configured as a rotation resistance device that provides resistance to relative rotation between the case 3 and the rotating body 5.

  The case 3 includes a main body wall portion 9, a first side wall portion 11 and a second side wall portion 13, and a support cylinder portion 15. The case 3 is integrally formed of a magnetic body as a whole except for the first side wall portion 11.

  The main body wall portion 9 has a cylindrical shape, and a first side wall portion 11 and a second side wall portion 13 are provided on both sides in the axial direction. The main body wall 9 divides the storage chamber 17 inside together with the first and second side walls 11 and 13. In the storage chamber 17, the magnetorheological fluid F is enclosed and the rotating body 5 is stored.

  The first side wall portion 11 is attached to the case 3 as a cap, is formed separately from the main body wall portion 9, and is fixed to one inner periphery of the main body wall portion 9. The first side wall portion 11 is formed in a disc shape by a nonmagnetic material such as copper, aluminum, or resin that can ignore the influence of the magnetic field as a whole. The first side wall portion 11 of the present embodiment is adapted to absorb the volume change of the magnetorheological fluid F in the storage chamber 17. This will be described later.

  The second side wall portion 13 is integrally formed on the other side inner periphery of the main body wall portion 9. The 2nd side wall part 13 is the surrounding shape as a whole, and is comprised by the side wall part main body 13a and the connection part 13b. The side wall portion main body 13a is disposed on the inner periphery of the main body wall portion 9 of the case 3 via the working chamber 17a. The outer peripheral part of the side wall part main body 13a is integrally connected to the main body wall part 9 by a connecting part 13b that is thinner in the axial direction than the side wall part main body 13a. A support tube portion 15 is integrally provided on the inner peripheral portion of the side wall portion main body 13a.

  The support cylinder part 15 is a hollow cylindrical body that extends from the inner periphery of the side wall part main body 13 a of the second side wall part 13 toward the first side wall part 11. A clearance for passing the flange portion 25 of the rotating body 5 is secured between the tip of the support cylinder portion 15 and the first side wall portion 11.

  A communication hole 19 that communicates the inside and outside of the case 3 in the axial direction is defined in the inner periphery of the support cylinder portion 15. The rotation shaft portion 21 of the rotating body 5 is inserted into the communication hole 19. In addition, you may abbreviate | omit the support cylinder part 15 and provide the communicating hole 19 within the range of the plate | board thickness of the side wall part main body 13a of the 2nd side wall part 13. As shown in FIG.

  The rotating body 5 is one in which the rotating shaft portion 21 and the rotating body main body 23 are integrally formed of a magnetic body.

  The rotating shaft portion 21 is inserted through the communication hole 19 of the support cylinder portion 15 of the case 3 as described above, and is supported so as to be relatively rotatable with respect to the support cylinder portion 15. Accordingly, the rotating body 5 is supported by the case 3 via the rotating shaft portion 21 and the support cylinder portion 15 so as to be relatively rotatable. In addition, the support structure of the rotating shaft portion 21 will be described later.

  The rotating body main body 23 is a part that is accommodated in the accommodating chamber 17 in the case 3. The rotating body main body 23 includes a flange portion 25 and a rotating cylinder portion 27.

  The flange portion 25 has a disk shape extending in the radial direction from the end portion of the rotating shaft portion 21 in the accommodation chamber 17. One side surface 25 a in the axial direction of the flange portion 25 faces the first side wall portion 11 with a gap in the axial direction. The other side surface 25b of the flange portion 25 faces the support cylinder portion 15 and an electromagnetic coil 7 described later with a gap therebetween. The other side surface 25b of the flange portion 25 is provided with a bulging portion 25c bulging in the axial direction, and the bulging portion 25c has a gap in the radial direction from the outer peripheral side with respect to the tip of the support tube portion 15. Facing each other.

  An oil passage 25d penetrating in the axial direction is provided in an intermediate portion between the inner and outer circumferences of the flange portion 25. A plurality of oil passages 25d are arranged at predetermined intervals in the circumferential direction of the flange portion 25. The outer peripheral portion of the flange portion 25 faces the working chamber 17a of the storage chamber 17, and is coupled to a rotating cylinder portion 27 located in the working chamber 17a.

  The rotating cylinder part 27 extends along the main body wall part 9 on the outer peripheral side of the electromagnetic coil 7. The outer periphery of the rotating cylinder part 27 is opposed to the inner periphery of the main body wall part 9 in the radial direction with a gap, and the inner periphery of the rotating cylinder part 27 is the outer periphery of the side wall part main body 13a of the second side wall part 13 at the tip part. Opposite to each other in the radial direction with a gap.

  A magnetic path by the electromagnetic coil 7 is formed between the rotating cylinder portion 27 and the flange portion 25 of the rotating body 5 and the main body wall portion 9 and the supporting cylinder portion 15 of the case 3, and the magnetic flux is a loop-shaped magnetic flux. Loop M will pass.

  The electromagnetic coil 7 is disposed on the outer periphery of the support cylinder portion 15 having a smaller diameter than the side wall portion main body 13 a of the second side wall portion 13. In this state, the electromagnetic coil 7 is supported by a retaining member 29 such as a snap ring that is prevented from being detached from the outer periphery of the support cylinder portion 15.

  Thus, the electromagnetic coil 7 constitutes an electromagnet having the support cylinder portion 15 and the side wall portion main body 13a of the second side wall portion 13 as a yoke. Therefore, the electromagnetic coil 7 can form the magnetic flux loop M via the support cylinder part 15 and the side wall part main body 13 a of the second side wall part 13. This magnetic flux loop M changes the viscosity of the magnetorheological fluid F between the case 3 and the rotating body 5 to generate a braking force between the case 3 and the rotating body 5. Specifically, it will be described later together with the operation of the braking device 1.

[Structure of the first side wall]
FIG. 2 is a cross-sectional view showing a state where the first side wall 11 is elastically deformed.

  The first side wall portion 11 of this embodiment is configured as an elastically deformable member that is elastically deformed according to the pressure in the storage chamber 17 and changes the volume in the storage chamber 17. This makes it possible to absorb volume changes such as thermal expansion of the magnetorheological fluid F during operation of the braking device 1.

  The first side wall portion 11 as the elastic deformation member may be partially or entirely elastically deformed. In this embodiment, as shown in FIGS. 1 and 2, the first side wall portion 11 is constituted by the fixing portion 11a, the side wall portion main body 11b, and the bent portion 11c, and at least a part of the bent portion 11c is elastic. The structure is deformed. However, if the entire first side wall 11 is made of an elastically deformable elastic member such as rubber, the entire first side wall 11 can be elastically deformed.

  The fixed portion 11a is formed in an annular shape, and has a thicker plate thickness than the side wall portion main body 11b and the bent portion 11c of the first side wall portion 11. The outer periphery of the fixed portion 11 a is fitted to the inner periphery of the main body wall portion 9 of the case 3. An annular seal member 31 such as an O-ring is held between the fixed portion 11 a and the main body wall portion 9. In the present embodiment, the seal member 31 is held in a circular recess 11aa formed in the fixed portion 11a of the first side wall portion 11. However, the recess 11aa may be provided in the main body wall 9 of the case 3.

  The outer peripheral side of the fixed portion 11 a is abutted against the stepped portion 9 a of the main body wall portion 9 in the case 3, and is prevented from being removed by a retaining member 33 such as a snap ring outside the case 3. Thereby, fixation to the main body wall part 9 of the fixing | fixed part 11a is made | formed. On the inner peripheral side of the fixed part 11a, a side wall part body 11b is supported via a bent part 11c.

  The side wall part main body 11 b has a disk shape that constitutes a main part of the first side wall part 11. A convex bent portion 11ba is provided in the case 3 at the axial center of the side wall portion main body 11b. The plate thickness of the side wall portion main body 11b is, for example, about 2 mm in the case of resin and about 0.2 mm in the case of metal, and can be elastically deformed according to the pressure of the storage chamber 17 in the case 3. . However, the side wall portion main body 11b may be configured not to be elastically deformed according to the pressure in the storage chamber 17 by increasing the plate thickness, changing the material, or the like.

  The bending part 11c couple | bonds between the fixing | fixed part 11a and the side wall part main body 11b, and elastically supports the side wall part main body 11b with respect to the fixing | fixed part 11a. The bent portion 11c of the present embodiment is a curved portion constituted by a first curved portion 11ca that curves convexly out of the case 3 and a second curved portion 11cb that curves convexly into the case 3. Note that one or both of the first and second bending portions 11ca and 11cb may be changed from a curved shape to a bent shape. Further, the number of the curved portions is arbitrary, and can be appropriately set within a range in which elastic deformation is possible in consideration of the expansion coefficient of the magnetorheological fluid F and the like.

  By setting the radius of curvature of the first curved portion 11ca, the convex top portion is offset inward in the axial direction from the one end edge portion 9b of the main body wall portion 9 by the chamfered portion 9c. The second bending portion 11cb is set to have a smaller radius of curvature than the first bending portion 11ca.

  Thereby, the bending part 11c is holding | maintaining the side wall part main body 11b in the position offset further inside in the axial direction rather than the top part of 1st curved part 11ca in the normal time of FIG. Then, the bending portion 11c is elastically deformed according to the pressure increase in the housing chamber 17 of the case 3 as shown in FIG. 2 and displaces the side wall portion main body 11b toward the outside of the case 3.

[Support structure of rotating shaft]
As shown in FIG. 1, the rotating shaft portion 21 of the present embodiment has an inner end portion 21 a, an intermediate portion 21 b, and an outer end portion 21 c having different diameters formed in order from the inside of the case 3. In addition, the rotating shaft part 21 may be comprised, for example as a rod-shaped body which has a fixed diameter, and the setting of a diameter is free.

  The inner end portion 21 a is integrally coupled to the flange portion 25 of the rotating body 5. The intermediate part 21b is formed with a smaller diameter than the inner end part 21a, and has a stepped shape between the intermediate part 21b and the inner end part 21a. The outer end portion 21 c protrudes outward with respect to the case 3. The outer end portion 21c is formed with a smaller diameter than the intermediate portion 21b, and has a stepped shape between the outer end portion 21c and the intermediate portion 21b. The outer end portion 21c is coupled to a movable side (not shown) such as a braking target. In this case, the rotating body 5 is the movable side, and the case 3 is the fixed side. Conversely, the case 3 may be coupled to a braking object or the like to form a movable side, and the outer end 21c may be coupled to the fixed side to make the rotating body 5 the fixed side.

  The communication hole 19 that supports the rotating shaft portion 21 includes a bearing hole portion 19a and a fitting hole portion 19b.

  The bearing hole portion 19a rotatably supports the rotating shaft portion 21 of the rotating body 5 via a pair of bearings 35a and 35b as bearings. In the present embodiment, the bearing hole portion 19a is positioned on the outer periphery of the intermediate portion 21b of the rotating shaft portion 21 of the rotating body 5, and the bearing hole portion 19a supports the intermediate portion 21b by the bearings 35a and 35b.

  One bearing 35a is abutted against the inner wall of the bearing hole 19a in the axial direction. The other bearing 35b is abutted in the axial direction against one bearing 35a via a spacer 37 disposed between the pair of bearings 35a and 35b, and is secured by retaining members 39a and 39b such as inner and outer peripheral snap rings. The retaining is made.

  The outer peripheral side retaining member 39 a is fixed to the inner periphery of the support cylinder portion 15 and abuts on the outer race 35 ba of the bearing 35 b, and the inner peripheral side retaining member 39 b is fixed to the outer periphery of the rotating shaft portion 21. It contacts the inner race 35bb of the bearing 35b. The spacer 37 will be described later.

  The fitting hole portion 19 b is disposed on the inner side of the case 3 (inside the housing chamber 17) than the bearing hole portion 19 a, and the inner periphery thereof is fitted to the outer periphery of the rotating shaft portion 21 so as to be relatively rotatable. The fitting hole portion 19b of the present embodiment is located on the outer periphery of the inner end portion 21a of the rotating shaft portion 21, and the inner periphery is fitted to the outer periphery of the inner end portion 21a. A seal member 41 and a filter member 43 are interposed between the inner periphery of the fitting hole portion 19b and the rotary shaft portion 21.

  The seal member 41 is for enclosing the magnetorheological fluid F and is an annular X-ring in this embodiment. The seal member 41 is not limited to the X ring, and may be an O ring or the like.

  The seal member 41 of the present embodiment is held in an annular seal recess 15 a provided on the inner periphery of the support cylinder portion 15, and the inner periphery slides on the outer periphery of the inner end portion 21 a of the rotary shaft portion 21 to provide a sealing property. Secure. However, the seal recess may be provided on the rotating shaft side, and the seal member may be held on the rotating shaft side.

  The filter member 43 is disposed on the inner side of the case 3 with respect to the seal member 41 (inside the storage chamber 17), and restricts movement of magnetic particles such as iron powder contained in the magnetic viscous fluid F toward the seal member 41. .

  The filter member 43 of this embodiment is annular and is held in a filter recess 15 b that is annularly provided along the inner periphery of the support cylinder 15. However, the filter recess may be provided on the rotating shaft portion side, and the filter member may be held on the rotating shaft portion side. The filter member 43 has an inner periphery that is in sliding contact with the outer periphery of the rotary shaft portion 21, and is located between the fitting hole portion 19 b of the communication hole 19 and the inner end portion 21 a of the rotary shaft portion 21 toward the magnetic particle seal member 41. Certainly restrict the movement of

  The material of the filter member 43 is not particularly limited as long as it can transmit the fluid in the magnetorheological fluid F reaching the seal member 41 and can capture the magnetic particles. For example, the filter member 43 can be made of a fiber aggregate such as a so-called soft wiper or felt, or a porous material such as a sponge.

[Spacer structure]
FIG. 3 is an enlarged sectional view showing the periphery of the spacer.

  The spacer 37 of this embodiment is made of a magnetic material and includes a spacer body 37a and a protruding portion 37b.

  The spacer main body 37a has an annular shape formed along the inner periphery of the support cylinder portion 15, and the outer races 35aa and 35ba of the pair of bearings 35a and 35b are in contact with both ends.

  The protruding portion 37 b protrudes radially inward from the spacer body 37 a and partitions the gap G between the rotating shaft portion 21. The gap G has a size that can form a magnetic path as a path of a branch portion M2 of a magnetic flux loop M described later between the rotating shaft portion 21 and the support cylinder portion 15.

  In the present embodiment, the protruding portion 37b is an annular shape formed along the inner periphery of the spacer body 37a, and divides the gap G from the outer periphery of the rotating shaft portion 21 in the entire circumferential direction. However, the projecting portion 37b does not need to be formed in an annular shape. For example, a configuration in which a plurality of projecting pieces are provided at intervals in the circumferential direction or a single projecting piece is provided in a part of the spacer body 37a in the circumferential direction. It may be a configuration.

  The protruding portion 37b is located between the inner races 35ab and 35bb of the bearings 35a and 35b, but a clearance in the axial direction is secured between the inner races 35ab and 35bb.

[Brake operation]
For example, the braking device 1 couples the case 3 to the fixed side and the rotating shaft portion 21 of the rotating body 5 to the movable side such as a braking target, and generates braking torque by energization control of the electromagnetic coil 7.

  While the electromagnetic coil 7 is not energized, the viscosity of the magnetorheological fluid F is low, and the relative rotation between the rotating body 5 and the case 3 is performed smoothly.

  When the electromagnetic coil 7 is energized, a magnetic flux loop M is formed as shown in FIG. 1, the viscosity of the magnetorheological fluid F becomes high, and the relative rotation between the rotating body 5 and the case 3 is restricted. This produces a braking torque.

  Specifically, the main part M1 of the magnetic flux loop M passes from the support cylinder part 15 through the side wall part main body 13a of the second side wall part 13 and through the rotary cylinder part 27 of the rotating body 5 to the main body wall part of the case 3. To 9. From the main body wall portion 9, the main body portion M1 of the magnetic flux loop M avoids the low magnetic resistance portions 45a, 45b, and 45c, passes through the rotating cylinder portion 27 and the main body wall portion 9 of the rotating body 5, and rotates the rotating body 5. From the cylindrical portion 27 to the flange portion 25.

  In the flange part 25, the branch part M2 branches from the main part M1 of the magnetic flux loop M. That is, the main part M1 of the magnetic flux loop M reaches from the bulging part 25c of the flange part 25 to the support cylinder part 15 of the case 3 to complete the loop. On the other hand, the branch part M2 extends from the flange part 25 of the rotating body 5 to the support cylinder part 15 of the case 3 from the spacer 37 between the bearings 35a and 35b via the inner end part 21a and the intermediate part 21b of the rotary shaft part 21. .

  At this time, the magnetorheological fluid F has spread across the gap between the case 3 and the rotating body 5, between the second side wall portion 13 of the case 3 and the rotating cylinder portion 27 of the rotating body 5, and between the rotating cylinder portion 27 and the case. 3 between the main body wall portion 9 and the flange portion 25 of the rotating body 5 and the support cylinder portion 15 of the case 3. For this reason, the viscosity of the magnetorheological fluid F changes between the case 3 and the rotating body 5 due to the passage of the main part M1 of the magnetic flux loop M. Thereby, in the braking device 1, braking torque can be generated between the case 3 and the rotating body 5 that rotate relative to each other.

  Here, the magnetorheological fluid F spreading in the gap between the case 3 and the rotating body 5 is also interposed between the rotating shaft portion 21 of the rotating body 5 and the support cylinder portion 15 of the case 3. The magnetic particles contained in the magnetorheological fluid F are captured by the filter member 43, and the fluid from which the magnetic particles have been removed is supplied to the seal member 41 located downstream thereof. .

  For this reason, the sealing member 41 can ensure sealing performance while being lubricated and is prevented from being damaged by the magnetic particles. As a result, the braking device 1 can suppress the leakage of the magnetorheological fluid F and stably generate the braking torque.

  When the braking torque is generated, the branching portion M2 of the magnetic flux loop M passes through the rotating shaft portion 21, so that the cross-sectional area of the portion functioning as the yoke can be increased, and the magnetic flux of the magnetic flux loop M can be increased. As a result, the magnetic flux loop M can increase the magnetic flux density in a range where the main portion M1 and the branch portion M2 are not branched.

  That is, in the present embodiment, the magnetic flux density of the magnetic flux loop M is between the second side wall portion 13 of the case 3 and the rotating cylinder portion 27 of the rotating body 5 and between the rotating cylinder portion 27 and the main body wall portion 9 of the case 3. Increases, and higher braking torque can be generated.

  During such a braking operation, the magnetorheological fluid F may generate heat and thermally expand. In the present embodiment, the volume change of the magnetorheological fluid F due to such thermal expansion can be absorbed by the first side wall portion 11 being elastically deformed to the outside of the case 3.

  Specifically, when the magnetorheological fluid F is thermally expanded, the pressure in the housing chamber 17 of the case 3 increases. Accordingly, the first side wall portion 11 can increase the volume in the storage chamber 17 by elastically deforming the bent portion 11c and displacing the side wall portion main body 11b toward the outside of the case 3 as shown in FIG. . At this time, the side wall portion body 11b itself is also elastically deformed so as to bulge outward depending on the pressure. Thereby, the volume in the storage chamber 17 can be further increased. By such an increase in volume, an increase in the volume of the magnetorheological fluid F due to thermal expansion can be absorbed.

  When the thermally expanded magnetorheological fluid F is cooled and its volume is reduced, the pressure in the housing chamber 17 of the case 3 is reduced. Thereby, as for the 1st side wall part 11, the bending part 11c and the side wall part main body 11b will return from an elastic deformation state, and the volume in the storage chamber 17 will reduce. Such a decrease in volume can absorb the decrease in volume of the cooled magnetorheological fluid F.

[Effect of Example 1]
The braking device (rotational resistance device) 1 of this embodiment rotates the rotating body 5 via a spacer 37 between a pair of bearings 35a and 35b that supports the rotating shaft portion 21 so as to be relatively rotatable with respect to the support cylinder portion 15. A magnetic path extending from the shaft portion 21 to the support cylinder portion 15 can be formed. Thereby, the branch part M2 can be formed in addition to the main part M1 of the magnetic flux loop M using the rotating shaft part 21, and a higher braking torque can be generated without increasing the size of the braking device 1. it can. Alternatively, the size of the braking device 1 can be reduced without reducing the braking torque.

  In the present embodiment, the spacer 37 is annular as a whole, and the projecting portion 37b defines a gap G between the outer periphery of the rotary shaft portion 21 in the entire circumferential direction, and therefore the branching portion M2 of the magnetic flux loop M in the entire circumferential direction. Thus, higher braking torque or downsizing of the braking device 1 is realized.

  In this embodiment, since the electromagnetic coil 7 is positioned on the outer periphery of the support cylinder portion 15, it is possible to reduce the size of the braking device 1, while realizing a higher braking torque or further size reduction of the braking device 1. it can.

1 Braking device (rotational resistance device)
3 Case 5 Rotating body 7 Electromagnetic coil 15 Supporting cylinder portion 21 Rotating shaft portion 35a, 35b Bearing 35aa, 35ba Outer race 35ab, 35bb Inner race 37 Spacer 37a Spacer body 37b Protruding portion F Magnetorheological fluid G Gap

Claims (4)

A rotational resistance device that encloses a magnetorheological fluid in a case of magnetic material and accommodates the rotating body of the magnetic body so as to be relatively rotatable, and changes the viscosity of the magnetorheological fluid by magnetic flux of an electromagnetic coil between the case and the rotating body. Because
A support cylinder portion provided in the case and communicating between the inside and the outside of the case;
A rotating shaft portion provided in the rotating body and inserted through the support cylinder portion;
A pair of bearings that rotatably support the rotating shaft with respect to the support cylinder;
A spacer disposed between the pair of bearings,
The spacer includes a spacer main body with which the outer race of the pair of bearings abuts, and a gap that protrudes radially inward from the spacer main body to form a magnetic path for the magnetic flux between the rotating shaft portion and the support cylinder portion. And a projecting portion that partitions between the rotating shaft portion and
A rotation resistance device. The rotation resistance device according to claim 1,
The spacer body is an annular shape formed along the inner periphery of the support cylinder portion,
The protrusion is a ring formed along the inner periphery of the spacer body.
A rotation resistance device. The rotation resistance device according to claim 2,
The protruding portion defines the gap between the projecting portion and the outer peripheral surface of the rotating shaft portion in the entire circumferential direction.
A rotation resistance device. The rotation resistance device according to any one of claims 1 to 3,
The electromagnetic coil is located on the outer periphery of the support cylinder portion.
A rotation resistance device.

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