JP2010159776A - Magneto-rheological fluid device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily and surely seal a magneto-rheological fluid 4 in manufacturing a magneto-rheological fluid device 1. <P>SOLUTION: The magneto-rheological fluid device 1 includes an outer member 2 for sealing the magneto-rheological fluid 4, an inner member 3 arranged to be relatively displaced with respect to the outer member 2, a magnetic field generating means 34 for imparting a magnetic field to the magneto-rheological fluid 4 filled in a gap between the outer member 2 and the inner member 3, and an inflow opening 224 opened in the outer member 2. A fin 33 is formed in at least either one of the outer member 2 or the inner member 3. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to various devices using a magnetorheological fluid.

A magnetorheological fluid is a liquid in which magnetizable metal particles (magnetic particles) are dispersed in a dispersion medium. This magnetorheological fluid functions as a fluid when no magnetic field is applied, but when a magnetic field is applied, the magnetic particles form clusters to increase the viscosity of the liquid and increase the internal stress of the liquid. Due to the increase of the internal stress, the magnetorheological fluid functions like a rigid body and exhibits a resistance against shear flow and pressure flow. This magnetorheological fluid is used for various mechanically operated devices such as brakes, clutches, and dampers (see, for example, Patent Document 1). Such a device includes an outer member that encloses a magnetorheological fluid, an inner member that is disposed within the outer member with a predetermined gap with respect to the inner surface of the outer member, and is configured to be relatively displaceable with respect to the outer member. , And the basic structure is that the gap is filled with a magnetorheological fluid. By applying a magnetic field to the magnetorheological fluid filled in the gap, the viscosity of the magnetorheological fluid in the gap is changed, which changes the relative displacement characteristics of the outer member and the inner member.
JP-T-2006-505937

  By the way, there is a demand for downsizing a device using a magnetorheological fluid. For this purpose, the gap between the outer member and the inner member (hereinafter also referred to as a device gap) must be as narrow as possible.

  However, when the gap between the devices is narrowed, there is a disadvantage that it becomes difficult to manufacture the device. That is, such a magnetorheological fluid device encloses the magnetorheological fluid in the outer member by flowing the magnetorheological fluid from an inlet opening in the outer member when the device is manufactured. At that time, the gap between the outer member and the inner member must be filled with the magnetorheological fluid. However, as the gap becomes narrower, it becomes more difficult to fill the magnetorheological fluid. For this reason, for example, it is necessary to take measures such as pouring the magnetorheological fluid into the outer member in a state where the magnetorheological fluid is at a high temperature to reduce the viscosity and the inside of the outer member is evacuated. However, the necessity of such a measure has a problem that the process of enclosing the magnetorheological fluid becomes complicated and disadvantageous in terms of manufacturing cost. Even if such a measure is adopted, when the gap between the devices is narrow, the magnetorheological fluid is not always filled therewith, and there is a possibility that the product characteristics may vary during mass production.

  This invention is made | formed in view of this point, The place made into the objective is to manufacture a magnetorheological fluid easily and reliably in manufacture of a magnetorheological fluid device.

  The magnetorheological fluid device includes a magnetorheological fluid, an outer member enclosing the magnetorheological fluid, a predetermined gap with respect to the inner surface of the outer member in the outer member, and the magnetorheological fluid device with respect to the outer member. An inner member configured to be relatively displaceable, magnetic field generating means for changing the viscosity of the magnetorheological fluid in the gap by applying a magnetic field to the magnetorheological fluid filled in the gap, and the outer An inlet opening in the member, and at least one of the outer member and the inner member, when the magnetorheological fluid flows into the outer member through the inlet, the outer member and the inner member are With the relative displacement, fins are formed to flow the magnetorheological fluid so that the gap is filled with the magnetorheological fluid. To have.

  According to this configuration, when the magnetorheological fluid is allowed to flow into the outer member, the outer member and the inner member are relatively displaced. Here, the relative displacement may be a relative displacement related to the operation of the device (after manufacture), or may be a relative displacement at the time of manufacturing the device that is unrelated to the operation of the device. That is, for example, the operation of the damper including the cylinder (outer member) and the piston (inner member) is that the piston is relatively displaced in the axial direction of the cylinder. The cylinder and the piston may be relatively displaced in the center direction. In contrast, by allowing the piston to rotate relative to the cylinder center during manufacture, when the magnetorheological fluid is allowed to flow into the cylinder, the cylinder and piston are centered about the cylinder axis. You may make it rotate relatively.

  Fins are formed on at least one of the outer member and the inner member. With the relative displacement of the outer member and the inner member, the fin can push out the magnetorheological fluid that has flowed into the outer member through the inlet. The resulting flow causes the magnetorheological fluid to reach every corner in the outer member and reliably fills the gaps in the device. Thus, the work of the magnetorheological fluid sealing process is simplified to reduce the manufacturing cost, and variations in the characteristics of the magnetorheological fluid device are also avoided.

  The inner member is provided so as to be rotatable relative to the outer member around a predetermined rotation axis, the inflow port opens at a position near the rotation shaft, and the fin includes the outer member and The inner member may be configured to flow in a radially outward direction when the inner member rotates relative to the rotation axis to flow in the vicinity of the rotation axis.

  The magnetorheological fluid that has flowed into the outer member near the center of the device flows radially outward by the fins so that the magnetorheological fluid can be efficiently distributed to every corner of the outer member. Become. As a result, the gap between the devices is surely filled with the magnetorheological fluid, facilitating the manufacture of the device, and advantageous in eliminating the device characteristic variation.

  The magnetorheological fluid may contain magnetic particles containing nano-size magnetizable metal nanoparticles and a dispersion medium for dispersing the magnetic particles. The nano-size here means a size of about 1 to several hundred nanometers (nm).

  When the diameter of the magnetic particles contained in the magnetorheological fluid is relatively large, the magnetic particles come into contact with the wall surfaces constituting the gap even if the gap between the devices is to be narrowed. This increases the operating resistance of the device and causes wear of the wall surface and device seal. That is, the minimum gap of the device is limited by the diameter of the magnetic particles contained in the magnetorheological fluid.

  In the above configuration, the magnetic particles contained in the magnetorheological fluid are nano-sized and extremely small. For this reason, even if the gap between the devices is narrowed, the magnetic particles are prevented from coming into contact with the wall surfaces constituting the gaps, and the operation of the device is not hindered and the wall surfaces and the seal are worn. Is prevented. That is, the device can be miniaturized by making the gap as narrow as possible. At the same time, it is possible to prevent the wear of the wall surface and the seal and the like, thereby extending the life of the device.

  As described above, according to the present invention, when the magnetorheological fluid is sealed in the outer member by forming fins on at least one of the outer member and the inner member, the magnetorheological fluid is placed in the gap of the device. It can be filled reliably and easily. As a result, at the time of mass production, the manufacturing cost can be reduced, and variations in device characteristics can be prevented.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the following description of the preferred embodiment is merely illustrative in nature, and is not intended to limit the present invention, its application, or its use.

  FIG. 1 shows a schematic configuration of a brake 1 as an example of a magnetorheological fluid device. In FIG. 1 and the like, the shaft member 5 to which the braking force is applied by the brake 1 is arranged to extend in the vertical direction, but the direction of the brake 1 is not limited. In the following, for the sake of convenience, the details of the brake 1 will be described with the upper side in FIG. 1 being the upper side and the lower side being the lower side.

  The brake 1 includes an outer member 2 that is externally inserted into the shaft member 5 and an inner member 3 that is disposed in the outer member 2.

  The outer member 2 is a container-like member configured by opening the upper and lower ends of the cylindrical peripheral wall 21 with an upper wall 22 and a lower wall 23, respectively. The outer member 2 encloses the magnetorheological fluid 4 therein. On the upper wall 22 of the outer member 2, a support portion 221 is formed at the center position so as to protrude upward. A bearing 222 that rotatably supports the upper end portion of the shaft member 5 is attached to the support portion 221, and a seal member 223 for sealing the inside of the outer member 2 is disposed. A through hole 224 that penetrates the upper wall 22 in the thickness direction is formed in the vicinity of the support portion 221 in the upper wall 22, and this through hole 224 has an inlet 224 for enclosing the magnetorheological fluid 4 therein. Function as. The inflow port 224 is sealed by attaching a sealing plug 225.

  The lower wall 23 of the outer member 2 is formed with a through hole 231 at the center position thereof through which the shaft member 5 is disposed. A bearing 232 that rotatably supports an intermediate portion of the shaft member 5 and a seal member 233 are disposed in the through hole 231.

  A plurality of (three in the illustrated example) disks 211 are integrated with the peripheral wall 21 so as to protrude radially inward from the inner peripheral surface of the outer wall 2 of the outer member 2. Is provided. The three disks 211 are arranged at equal intervals in the vertical direction at an intermediate position in the vertical direction of the outer member 2. Each disk 211 has a predetermined thickness when the upward surface and the downward surface face each other in the vertical direction, and is formed in an annular shape by extending along the inner peripheral surface of the peripheral wall 21 over the entire periphery. ing. Thus, a hole into which the inner member 3 is inserted is formed on the radial center side of each disk 211. A through hole 212 that penetrates in the thickness direction is formed in the peripheral wall 21 of the outer member 2 at a position corresponding to between adjacent disks 211, and this through hole 212 is used to enclose the magnetorheological fluid 4. It functions as an air vent hole 212 for venting air in the outer member 2. This air vent hole 212 is also sealed by attaching a sealing plug 213.

  The inner member 3 is a member that is externally fitted to the shaft member 5 and is configured to rotate integrally with the shaft member 5. The inner member 3 has a substantially cylindrical main body 31 and a plurality of (four in the illustrated example). The disc 32 and the fins 33 are provided. The main body 31 is a portion that is externally fitted to the shaft member 5, and a coil 34 serving as a magnetic field generating unit is disposed therein. By supplying a current to the coil 34 (note that the supply source is not shown), a magnetic field is applied to the magnetorheological fluid 4 in the outer member 2.

  The disk 32 is provided so as to rotate integrally with the main body 31. The four disks 32 are disposed at equal intervals in the vertical direction between the upper end and the lower end of the main body 31. Each disk 32 is provided so as to protrude outward in the radial direction from the outer peripheral surface of the main body 31, and the outer peripheral edge of each disk 32 is relative to the inner peripheral surface of the peripheral wall 21 of the outer member 2. It is located with a predetermined gap. The disk 211 of the outer member 2 and the disk 32 of the inner member 3 are alternately arranged in the vertical direction. Between the disk 211 of the outer member 2 and the disk 32 of the inner member 3, a magnetic viscosity is provided. A gap filled with the fluid 4 is formed. Here, in the brake 1, the magnetic particles contained in the magnetorheological fluid 4 are nano-sized as described later, whereby the gap between the disk 211 of the outer member 2 and the disk 32 of the inner member 3. Is configured to be extremely narrow. As a result, the brake 1 is reduced in size as a whole. In the example of the drawing, the size of the gap is exaggerated for easy understanding.

  The fin 33 is provided so as to rotate integrally with the main body 31 and the disk 32 so as to protrude upward from the upper end surface of the inner member 3, whereby the fin 33 is connected to the lower surface of the upper wall 22 of the outer member 2. It is located between the upper end surface of the member 3. As shown in FIG. 2, four fins 33 are arranged at equal angles in the circumferential direction, and each fin 33 corresponds to the outer peripheral surface of the shaft member 5 at the upper end surface of the inner member 3. It is arranged to extend while curving from the center side position outward in the radial direction.

  Note that the brake 1 shown in FIG. 1 is schematically illustrated. For example, a specific configuration necessary for disposing the inner member 3 in the outer member 2 is not illustrated. As such a configuration, an appropriate known configuration can be adopted.

  The magnetorheological fluid 4 is a liquid in which magnetic particles are dispersed in a dispersion medium. In this embodiment, the magnetic particles are composed of nano-sized metal particles (metal nanoparticles). The magnetic particles are made of a magnetizable metal material. The metal material is not particularly limited, but a soft magnetic material is preferable. Examples of soft magnetic materials include alloys such as iron, cobalt, nickel, and permalloy. As for a metal nanoparticle, it is desirable that the average particle diameter is 20-500 nm, More preferably, it is 70-200 nm. When the average particle diameter is 70 nm or more, a high MR effect can be obtained, and when the average particle diameter is 200 nm or less, deterioration of sedimentation property of the magnetorheological fluid 4 can be avoided. The magnetic particles may contain an aggregate in which metal nanoparticles are aggregated.

  The dispersion medium is not particularly limited, and a hydrophobic silicone oil can be given as an example. Depending on the type of the dispersion medium to be used, the magnetic particles may be subjected to surface modification having high affinity with the dispersion medium. By doing so, the dispersion stability of the magnetic particles is increased. For example, when hydrophobic silicone oil is used as the dispersion medium, it is preferable to subject the magnetic particles to surface modification with a coupling agent.

  The blending amount of the magnetic particles in the magnetorheological fluid 4 may be 3 to 40 vol%, for example.

  Various additives can also be added to the magnetorheological fluid 4 in order to obtain various desired characteristics.

  In the brake 1 configured as described above, a magnetic field is generated by supplying a predetermined current to the coil 34, and the magnetorheological fluid 4 filled in the gap between the disk 211 of the outer member 2 and the disk 32 of the inner member 3. The viscosity becomes higher. As a result, the shear stress between the disks 211 and 32 increases, and a braking force is applied to the shaft member 5 that is rotationally driven.

  When the magnetic viscous fluid 4 is sealed in the outer member 2 during the manufacture of the brake 1 having this configuration, the inlet 224 and the air vent hole are formed in the state in which the inner member 3 is assembled in the outer member 2 as shown in FIG. 212 is opened, and the magnetorheological fluid 4 is caused to flow into the outer member 2 through the inlet 224. At this time, for example, the outer member 2 and the inner member 3 are relatively rotated by rotating the inner member 3. With this relative rotation, the fin 33 provided on the inner member 3 starts to rotate. As a result, the magnetorheological fluid 4 flowing into the outer member 2 at a position near the shaft member 5 is radially moved by the fin 33. It will be pushed outward. In this way, the magnetorheological fluid 4 flows radially outward from the center side of the brake 1 and passes through the gap between the outer member 2 and the inner member 3 to reach every corner in the outer member 2. become. In this way, the magnetorheological fluid 4 is also filled in the gap between the disk 211 of the outer member 2 and the disk 32 of the inner member 3, which is particularly narrow. Thus, the magnetic viscous fluid 4 can be easily and reliably sealed by the fins 33 formed on the inner member 3. This is particularly effective in a device having a narrow gap such as the brake 1. As a result, it is possible to reduce the manufacturing cost and suppress characteristic variations.

  In addition, when enclosing the magnetorheological fluid in the outer member 2, the temperature of the magnetorheological fluid 4 may be increased to decrease the viscosity, or the inner member 2 may be evacuated. By combining these measures, the magnetic viscous fluid 4 can be more reliably sealed.

  FIG. 3 shows a modification of the brake 1. This brake 1 is provided with fins 24 on the outer member 2 instead of providing fins on the inner member 3. In addition, in the brake 1 shown in FIG. 3, about the same structure as the brake 1 shown in FIG. 1, the same code | symbol is attached | subjected and description is abbreviate | omitted suitably.

  In the brake 1, the fin 24 is formed so as to protrude downward from the lower surface of the upper wall 22 of the outer member 2. Although not shown in the drawings, a plurality of (for example, four) fins 24 are arranged in the same manner as the brake 1 shown in FIG. 1, and the plurality of fins 24 are spaced at equal angles in the circumferential direction. It is arranged. Each fin 24 extends while being curved from the center side position, which is a position in the vicinity of the shaft member 5, outward in the radial direction.

  Even in this configuration, when the magnetorheological fluid 4 is sealed in the outer member 2, the outer member 2 and the inner member 3 are relatively rotated. With this relative rotation, the magnetorheological fluid 4 that has flowed into the outer member 2 through the inlet 224 flows from the center side of the brake 1 toward the outer side in the radial direction, and the outer member 2 and the inner member 3. It spreads to every corner in the outer member 2 through the gap between the two. Thus, the magnetic viscous fluid 4 can be easily and reliably sealed. In addition, you may make it provide a fin in both the outer member 2 and the inner member 3. FIG.

  The positions where the fins are formed in the brake 1 are not limited between the lower surface of the upper wall 22 of the outer member 2 and the upper end surface of the inner member 3, as shown in FIGS. Can be formed. For example, fins may be formed on a disk or the like in the outer member 2 and / or the inner member 3. Moreover, what is necessary is just to set the shape etc. of a fin suitably according to the position which arrange | positions it, and the direction which wants to flow the magnetorheological fluid 4. FIG. As shown in FIG. 2 and the like, the fins may be curved as necessary, or the fins may be formed linearly.

  The position of the inlet for allowing the magnetorheological fluid 4 to flow into the outer member 2 is not limited to the upper wall 22 of the outer member 2 as shown in FIG. Is possible. Further, the position of the air vent may be set as appropriate according to the position of the inlet.

  Further, the inlet may be provided on the inner member 3 side. Although illustration is omitted, for example, the shaft member 5 is formed in a hollow shape, and a communication hole that opens in the outer member 2 via the inner member 3 is formed at a midway position in the vertical direction of the shaft member 5. May be. There may be one or more such communication holes. In this configuration, the magnetorheological fluid 4 flows into the outer member 2 from the inside of the shaft member 5 through the communication hole. Therefore, the opening of the communication hole corresponds to the inflow port. Even when such a configuration is adopted, the fins can be provided at appropriate positions in the outer member 2 and / or the inner member 3.

  Moreover, the structure of a brake is not restricted to the said structure, It is possible to change suitably. For example, the number of disks is not limited to the example in the figure.

  The present invention is not limited to application to the brake 1. The present invention can be widely applied to various magneto-rheological fluid devices including an outer member and an inner member such as a clutch and a damper. Further, the relative movement of the outer member and the inner member performed when the magnetic viscous fluid is sealed is not limited to the relative rotation as described above. The relative movement may be linear depending on the structure of the device. The arrangement and shape of the fins may be appropriately set in consideration of the shape of the outer member and the inner member, the direction of relative movement thereof, the position of the inlet, and the like.

  Furthermore, the magnetorheological fluid 4 is not limited to a magnetorheological fluid in which the magnetic particles contained therein are nano-sized. It may be a magnetorheological fluid in which the size of the magnetic particles is larger than that. However, from the viewpoint of reducing the size of the magnetorheological fluid device, the magnetic particles are preferably nano-sized magnetorheological fluids.

  As described above, the present invention is useful for various devices using a magnetorheological fluid.

It is sectional drawing which shows schematic structure of the brake using a magnetorheological fluid. It is a perspective view of an inner member. FIG. 2 is a view corresponding to FIG. 1 illustrating a brake having a configuration different from that of FIG. 1.

1 Brake (Magnetorheological fluid device)
2 Outer member 24 Fin 224 Inlet 3 Inner member 33 Fin 34 Coil (magnetic field generating means)
4 Magnetorheological fluid 5 Shaft member (Rotating shaft)

Claims (3)

A magnetorheological fluid;
An outer member enclosing the magnetorheological fluid;
An inner member disposed within the outer member with a predetermined gap with respect to the inner surface of the outer member, and configured to be relatively displaceable with respect to the outer member;
Magnetic field generating means for changing the viscosity of the magnetorheological fluid in the gap by applying a magnetic field to the magnetorheological fluid filled in the gap;
An inlet opening in the outer member,
A magnetorheological fluid device in which fins are formed on at least one of the outer member and the inner member. The magnetorheological fluid device of claim 1, wherein
The inner member is provided to be rotatable relative to the outer member around a predetermined rotation axis,
The inflow port is open at a position near the rotation axis;
The fin is configured to cause the magneto-rheological fluid flowing in the vicinity of the rotation shaft to flow outward in the radial direction when the outer member and the inner member relatively rotate around the rotation shaft. Magnetorheological fluid device. The magnetorheological fluid device according to claim 1 or 2,
The magnetorheological fluid is a magnetorheological fluid device containing magnetic particles containing nano-size magnetizable metal nanoparticles and a dispersion medium for dispersing the magnetic particles.

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