JP5527766B2 - Rotary braking device using magnetorheological fluid - Google Patents

Description

The present invention relates to a rotary braking device for a rotor that uses a magnetorheological fluid and an electromagnet or the like to apply a magnetic field thereto to brake a rotating shaft against a housing or the like around the rotating shaft.

In general, a clutch device and a brake device that perform braking such as transmitting or stopping rotation of a rotating body that rotates around an axis are known. As an example, a rotary braking device called a disc brake has been conventionally known. This disc brake has a structure in which a rotating body called a disc rotor is braked by a frictional force generated when the rotating body is sandwiched between two discs called brake pads disposed on both sides thereof. doing.

In this disc brake, a magnetic fluid is held in a gap between a disc rotor as a rotating body and a brake pad as a holding member on the fixed side, and a braking force applied to the rotating body is controlled by applying a magnetic field to the magnetic fluid. (Patent Document 1). However, such a rotary braking device (brake structure) has a problem in that external leakage of magnetic fluid cannot be prevented in a normal state where a magnetic field is not applied. In particular, when used for braking a rotating body with a precision device, it is necessary to prepare a sealing means capable of preventing such external leakage of fluid.

JP-A 61-290242 Japanese Patent Laid-Open No. 06-171484 JP 2009-117797 A

The present invention has been made in view of the above problems, and in a braking device of a rotor as a rotating shaft and a housing as an outer used in a brake device or a clutch device, a magnetic viscosity is provided in a gap between the rotor and the housing. It is an object of the present invention to provide a rotary braking device having a configuration capable of efficiently controlling braking of a rotor by using a fluid and simultaneously preventing external leakage of a magnetorheological fluid.

The rotor rotation braking device of the present invention comprises a rotor as an annular member that rotates relative to the housing in a hollow disk-shaped housing, and the housing so as to rotate together with the rotor. A magnetic disk coupled to the rotor between the rotor, an electromagnet disposed so as to sandwich the disk (with a gap), and providing a magnetic path in a direction to sandwich the disk when energized; It has. First, a magnetorheological fluid is held in a gap between the rotor or the disk and the housing or the electromagnet.

As a result, in the rotational braking device of the present rotor, when the electromagnet is energized, a shearing force acts between the magnetic disk and the yoke, and as a result, the rotation of the rotor coupled to the disk is also restricted.

It is also conceivable to hold a general lubricating oil in the gap, and the lubricating oil that is a non-magnetic material is advantageous in that it does not disperse the magnetic path from the electromagnet. However, in the case of a general lubricating oil, there is a drawback that since the viscosity is always high, the shearing force generated when the rotor rotates becomes resistance to rotation. In this respect, the magnetorheological fluid is advantageous because it has the property of developing viscosity only when a magnetic force is applied.

Further, the gap is physically sealed at an end located outside the rotation radius of the rotor, and conversely, a magnetic force is applied to the magnetorheological fluid held near the end located inside the rotation radius of the rotor. It is preferable to seal by disposing a permanent magnet.

The clearance outside the rotation radius of the rotor is preferably physically (structurally) secured since a strong centrifugal force acts upon rotation. On the contrary, the clearance inside the rotation radius of the rotor is often provided with a rotary bearing in the vicinity and is often difficult to physically seal, while the influence of centrifugal force due to rotation is relatively weak. Therefore, the end of the gap on the outer side of the radius of rotation is surely physically sealed, and the end of the gap on the inner side of the radius of rotation is provided with a permanent magnet in the vicinity and sealed with a magnetorheological fluid thickened by this magnetic force. It is supposed to stop (seal).

Moreover, it is preferable that a part of the gap to which the magnetic force of the permanent magnet is applied forms a so-called labyrinth structure.

As described above, a method of sealing the magnetorheological fluid held in the gap by the magnetic force of the permanent magnet is adopted as an example of the rotary braking device of the rotor. The gap under the influence of the magnetic force of the permanent magnet is used. If a part of the labyrinth structure has a labyrinth structure, the flow path of the magnetorheological fluid to be held has many bent portions, and the sealing force of this portion can be further increased. Therefore, a large viscosity is expressed only in the portion where sealing is desired to improve the sealing force, and other portions are prevented from becoming resistance to the rotational force. That is, the sealing force can be improved without reducing the rotational torque.

Furthermore, a flow path that is fluidly connected to the gap may be provided in the rotor so that a magnetorheological fluid is injected into the gap by centrifugal force accompanying rotation of the rotor.

This is because it is efficient to utilize the rotation of the rotor in order to fill (hold) the magnetorheological fluid in the gap.

Further, it is preferable that the permanent magnets are positioned substantially equidistant from each other with respect to the flow path, and the permanent magnets are opposed to each other with the same polarity.

When the permanent magnets are arranged to face each other with the same polarity, it is possible to simultaneously achieve a seemingly contradictory effect of a sealing action due to the thickening of the magnetorheological fluid and a smooth inflow of the magnetorheological fluid. First, as described above, the magnetorheological fluid in the gap between the housing or the like and the rotor or the like is thickened by applying the magnetic field by the permanent magnet as it is, and thus the sealing can be achieved. On the other hand, in the flow path in the rotor provided for allowing the magnetorheological fluid to flow into the gap between the housing and the rotor, the magnetic field is canceled by the permanent magnets having the same polarity across the flow path. The viscous fluid does not thicken, flows smoothly, and does not hinder injection into the gap.

According to the rotor rotational braking device of the present invention, the braking between the rotor and the housing can be sufficiently achieved by efficiently applying the magnetic force of the electromagnet to the disk during energization, and the magnetic viscosity is applied to the gap between the rotor and the housing. By holding the fluid, a sufficient sealing state can be ensured without reducing the rotational torque.

It is sectional drawing along the axis line of the rotating apparatus which has a seal structure using the magnetorheological fluid of this invention. FIG. 2 is an enlarged view of the right side of FIG. 1 excluding hatching processing. It is the enlarged view shown in the state which performed the hatching process in FIG. 1 about the area A shown in FIG. It is the enlarged view shown in the state which performed the hatching process in FIG. 1 about the area B shown in FIG.

First, referring to FIG. 1, one embodiment of a rotary braking device 10 using a magnetorheological fluid of the present invention is shown. Specifically, a cross-sectional view taken along the rotation axis of the rotary braking device is shown. 1 is symmetrical about the axis X, and the members shown on either the left or right side are the same members as those at positions symmetrical to this. 2 is an enlarged cross-sectional view generally showing the right side of the rotation axis X of the rotary braking device 10 of FIG. 1, and the hatching process used for each member of the cross-sectional view is omitted in consideration of ease of visual recognition. doing.

First, in the rotation braking device 10 of the present embodiment, a rotating body 12 that mainly rotates on a shaft, a fixed housing 18 that covers the periphery of the rotating body 12, an annular disk 26 that is coupled to the rotating body 12, and the rotating body 12 and the housing. 18 and the like, and the electromagnet 20 that applies a magnetic field to the disk 26 and the magnetorheological fluid 28 when an electric current is passed.

Rotating body (shaft and rotor) and housing First, the rotating body 12 includes a rod-shaped shaft 14 that rotates about an axis X, and a rotor 16 that extends in the radial direction from the shaft 14 and forms a substantially annular plate. And is composed of. The shaft 14 and the rotor 16 are integrally formed, and austenitic stainless steel (SUS304) is used as a nonmagnetic material.

The housing 18 functions as a casing member of the rotating body 12 and is fixed to the rotating body 12 that rotates about the shaft. Here, the rotating body 12 rotates about the axis and the housing 18 is fixed. However, it is only necessary that both rotate relatively, and the housing 18 rotates about the axis X, and the rotating body 12 may be fixed. More specifically, the housing 18 has a structure that covers the outer periphery of the rotor 16 so that the rotor 16 can rotate inside. The two plate-like members 18a and 18b arranged so as to face each other are screwed. It is comprised by combining with. The housing 18 is made of austenitic stainless steel (hereinafter referred to as “SUS304”) as a non-magnetic material like the rotating body 12.

Furthermore, the housing 18 is provided with an annular rotary bearing 32 centered on the axis X, one above the other. Since the rotary bearing 32 is an annular member centered on the axis X, the reference numerals 32a and 32b shown in FIG. 1 mean the same rotary bearing, and the reference numerals 32c and 32d are the same rotary bearing. is there. By inserting the shaft 14 into the two rotary bearings 32 and rotating the shaft 14, the rotating body 12 can rotate about the housing 18. The members disposed in the housing 18 to be described below are two sets of annular members formed in the direction of the axis X as in the case of the rotary bearing 32. Accordingly, the same members are displayed symmetrically on the paper surface of FIG. 1 (and FIG. 2), and each member disposed in the housing 18 is the paper surface of FIG. 1 (and FIG. 2). A pair of members is displayed in two vertically symmetrically.

Positional relationship between disk, electromagnet, and magnetorheological fluid A pair of annular plate members 26 are vertically coupled to the outer edge of the rotor 16 in the rotational radius direction. 3 is an enlarged view of an area A surrounded by a dotted line in FIG. As can be understood from FIG. 3 and FIGS. 1 to 2, the disk 26 has a part of the inner edge side 26 c coupled to the outer edge of the rotor 16, and the outer edge side 26 b of the disk 26 is connected to the rotor 16. It protrudes from the outer edge and is inserted into an electromagnet 20 (described later). The inner edge side 26c of the disk 26 is coupled to the rotor 16 by a screw 36 via an annular contact member 38.

Further, the outer edge side 26 b of the disk 26 protruding outward in the rotational radius direction from the outer edge end portion of the rotor 16 is inserted into the electromagnet 20. Here, the electromagnet 20 surrounds the coil 22 with a yoke 24 via a bobbin 23. The yoke 24 uses pure iron as a magnetic material. Further, the bobbin 23 between the coil 22 and the yoke 24 is inserted so as to cover the top surface side and the inner surface side (the bottom surface side and the inner surface side) of the coil 22 over the entire ring direction. In general, a magnetic body is used as a member corresponding to a bobbin in an electromagnet, but here, a sufficient magnetic path L (see arrow L in FIGS. 2 and 3) is formed by concentrating magnetic flux in the yoke 24. Therefore, SUS304, which is a nonmagnetic material, is used.

Here, the magnetic path L when the coil 22 is energized will be described with reference to FIGS. As described above, the lines of magnetic force (magnetic flux) generated from the coil 22 circulate mainly in the yoke 24 due to the presence of the auxiliary member 23 and the housing 18 which are non-magnetic materials, and generate a magnetic path L. In the case of the rotary braking device 10, means for concentrating the magnetic lines of force on the magnetic path L without dispersing the magnetic force lines is further provided, which will be described in detail later.

First, as shown in FIG. 3, the yoke 24 has a U-shaped cross-section opened to the rotor 16 side, and a first yoke 24a that can be divided into two parts in the vertical direction, and the disk 26 in combination with the first yoke 24a. And a second yoke 24b sandwiching the outer edge side 26b. Further, the first yoke 24a is generally fixed to the housing 18 without providing a gap. The second yoke 24b is mechanically coupled to and integrated with the bobbin 23 described above. The lines of magnetic force that have traveled in the first yoke 24 a are bent and travel to the outer edge side 26 b of the disk 26. In FIG. 3, it is as shown by the magnetic path L that bends from the left direction and proceeds substantially downward at a right angle. This is because the lines of magnetic force emitted from the first yoke member 24a are directed toward the disk 26 made of a material having a high magnetic permeability such as permalloy (Fe—Ni alloy).

However, it is preferable that the magnetic path L has a shape such that the magnetic lines of force traveling inside are not dispersed and released when energized. Next, the magnetic path L that has traveled from the first yoke member 24a to the outer edge side of the disk 26 travels in the disk 26 as it is and reaches the second yoke member 26b. Specifically, it is as referring to the magnetic path L in FIGS. A magnetic viscous fluid 28 is held in the “gap” between the disk 26 and the rotor 16 and the housing 18 and the electromagnet 20. However, in FIG. 1 to FIG. It can be said that the groove 26a also forms a part of the “gap” (hereinafter referred to as “gap 28” with a reference number).

Returning to FIG. 3, the description will be continued. The magnetic path L that has traveled past the disk 26 enters the second yoke member 24b and proceeds straight downward. And it passes the position of the rotation plane Y. Thereafter, the magnetic path L also proceeds symmetrically because it is vertically symmetric with respect to the rotational plane Y. Moreover, it is symmetrical up and down also about the structure of another member and the significance of a structure. This can be understood with reference to FIGS.

About filling of magnetorheological fluid Here, a method of filling the magnetorheological fluid 28 held in the gap between the rotor 16 and the disk 26 and the housing 18 and the electromagnet 20 (particularly the yoke 24) will be described. As shown in FIGS. 1 and 2, the shaft 14 has a flow path 12a in the lower part of the drawing plane than the rotation plane Y, and has a hollow structure opened to the outside at the lower end of the flow path 12a. The rotor 16 also includes a flow path 12b inside along the rotation plane Y. The flow path 12 b extends outward in the radial direction of the rotor 16, and is open to the outside at the outer edge end portion of the rotor 16. These flow paths 12a and 12b are fluidly connected in the vicinity of the intersection of the rotation axis X and the rotation plane Y. Although not shown in FIGS. 1 to 2, a plurality of flow paths 12 b may exist radially around the rotation axis X.

Next, filling of the magnetorheological fluid will be described. After assembling the rotary braking device, the magnetorheological fluid is press-fitted from the open end of the flow path 12a using a syringe or the like. When the magnetorheological fluid reaches the flow path 12b from the flow path 12a, it proceeds from the position of the rotation axis X toward the outer side of the rotation radius. The magnetorheological fluid is discharged from the outer edge of the rotor 16 into the gap 28, and the gap 28 is all replenished in order to be fluidly connected. In order to efficiently fill the gap 28 with the magnetorheological fluid, a blade 25 capable of stirring the fluid in the gap as shown in FIG. 3 may be provided, and the rotor 16 may be rotated to use the centrifugal force.

About prevention of leakage of magnetorheological fluid As described above, magnetorheological fluid filled outside the rotating radius of the rotating body 12 such as the rotor 16 is filled inside the rotating radius. At this time, rotary bearings 32a to 32d and the like exist at the inner end of the clearance radius of the gap 28, and external leakage of the magnetorheological fluid reaching this position becomes a problem. Certainly, in the vicinity of the rotary bearings 32a to 32d, the influence of the centrifugal force of the rotating body 12 is small, so that a large amount of magnetorheological fluid does not leak. However, there is a problem in that the viscosity of the magnetorheological fluid in a normal state is relatively small and is more likely to leak than a general lubricating oil. On the other hand, the low viscosity is advantageous in that a large shearing force acts in the gap 28 during rotation of the rotor 16 and the like, and resistance to rotational torque hardly occurs. The rotary braking device 10 of the present rotor is provided with means for reducing the leakage problem while taking advantage of this advantage.

FIG. 4 is an enlarged partial cross-sectional view of the area B surrounded by a dotted line in FIG. First, as shown in FIGS. 1 and 2, a seal block 30 is disposed on the inner side of the rotation radius than the contact member 38 of the disk 14 (on the left side in FIG. 2). The seal block 30 is a rolled steel material (SS400), which is a magnetic material, and is coupled to the housing 18 with screws 40. Further, as understood from reference numeral 30a in FIG. 4, the seal block 30 has a so-called labyrinth structure in which a surface treatment is performed on the gap side and a plurality of bent portions are provided in the gap. Further, a permanent magnet 34 is disposed inside the rotation radius of the seal block 30 (on the left side in FIG. 4). Further, a gap of a labyrinth structure is formed on the gap side of the permanent magnet 34 as in the case of the seal block 30 (see reference numeral 34a).

The magnetic force from the permanent magnet 34 acts on the magnetorheological fluid in the gap near the labyrinth structure of reference number 30a or reference number 34a. Here, the magnetorheological fluid used in the rotary braking device 10 of the present rotor is assumed to be obtained by dispersing nano-sized iron particles (magnetic material) produced by the arc plasma method disclosed in Patent Document 3 in a dispersion medium. However, other fluids may be used as long as they have a function called a so-called magnetorheological fluid.

Further, the state where the magnetic force acts on the magnetorheological fluid will be described. In the first place, a magnetorheological fluid is a liquid in which magnetizable metal particles are dispersed in a dispersion medium. This magnetorheological fluid functions as a fluid when there is no magnetic force, while when magnetic force is applied, metal 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.

For this reason, the magnetorheological fluid 28 is attracted to the lines of magnetic force (magnetic flux) traveling inside the gap, and the gap can be sealed with high pressure resistance by increasing the viscosity due to the generation of clusters. Thereby, external leakage of the magnetorheological fluid can be prevented. Furthermore, as described above, the sealing performance is further enhanced by providing the labyrinth structures 30a and 34a in the gap.

The permanent magnets 34 are arranged so that the same poles face each other with respect to the rotation plane Y. In the case of the example shown in FIGS. 2 and 4, they are arranged so as to face each other with the S pole. If the permanent magnet 34 is disposed so as to face the N pole and the S pole, the magnetorheological fluid thickens in the vicinity of the position indicated by reference numeral 12c in the flow path 12b, and the magnetic viscosity due to the rotation as described above. This is because sufficient fluid filling cannot be achieved.

The embodiment of the present invention has been described above, but the rotor rotation braking device of the present invention is not limited to this, and other embodiments that do not depart from the spirit and teaching of the claims. It will be apparent to those skilled in the art that variations and modifications exist.

DESCRIPTION OF SYMBOLS 10 ... Rotary brake device 12 ... Rotating body 14 ... Shaft 16 ... Rotor 18 ... Housing 20 ... Electromagnet 22 ... Coil (rotating shaft)
23 ... Bobbin 24 ... Yoke 26 ... Disk 26a ... Groove 28 ... Magnetorheological fluid (gap)
X ... rotation axis Y ... rotation plane

Claims (2)

A rotor as an annular member that rotates relative to the housing in a hollow disk-shaped housing;
A magnetic disk coupled to the rotor side between the housing and the rotor for axial rotation with the rotor;
A rotary braking device for a rotor provided with an electromagnet disposed so as to sandwich the disk and providing a magnetic path in a direction to sandwich the disk when energized,
A magnetorheological fluid is held in a gap between the rotor or the disk and the housing or the electromagnet,
The gap is
At the end located outside the turning radius of the rotor, it is physically sealed,
At the end located inside the rotation radius of the rotor, it is sealed by disposing a permanent magnet that gives magnetic force to the magnetorheological fluid held in the vicinity thereof,
A part of the gap to which the magnetic force of the permanent magnet is applied forms a labyrinth structure,
A rotary braking device for a rotor, wherein a flow path is provided in the rotor to fluidly connect to the gap so that a magnetorheological fluid is injected into the gap. The permanent magnets are positioned substantially equidistant from each other with respect to the flow path,
The rotary braking device according to claim 1, wherein the permanent magnets positioned substantially equidistant in the vertical direction face each other with the same polarity.

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