JPS63257431A - Assembly using magnetic fluid - Google Patents

Abstract

PURPOSE:To improve the reliability and endurability as an inertial damper, by filling up magnetic fluid in the annular space and by holding it with the flux in the gap. CONSTITUTION:Together with a permanent magnet 8 rotates a shaft 1 performing rotating motion. An inertial ring 9 rotates, however, at the speed slightly slower than the rotating speed of the shaft 1 owing to the friction between the permanent magnet 8 and magnetic fluid 4 and between the magnetic fluid 4 and inertial ring 9. If the shaft 1 is going to rotate at the speed higher than the average speed with the unevenness in rotation of a driving device, the rotating force will be reduced by the friction with the magnetic fluid 4. On the contrary, if it is going to rotate slower, the rotating force of the inertial ring 9 will act as a movement to rotate the permanent magnet 8, i.e. the shaft 1 faster through the magnetic fluid 4 since the inertial ring 9 rotates faster. In this way, the unevenness in rotation is reduced for the shaft 1 and the shaft 1 will be rotated smoothly at the speed as close as to the average speed.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to an assembly using magnetic fluid.
It particularly relates to an assembly suitable for use as an inertia damper or bearing.

(Prior art and its problems) For example, when a stepping motor is continuously sent a pulse signal to cause the motor to rotate continuously, an inertia damper is used to rotate a motor with uneven rotation at as uniform a speed as possible. There are many things to add (this is currently being done).

Conventional inertia dampers used for this purpose include those that utilize the viscosity of oil, those that utilize friction, and those that use permanent magnets. It is difficult to completely seal oil, and those that use friction have drawbacks such as problems with heat generation and contamination due to wear particles.

In order to improve these points, it is conceivable to use an inertia damper as shown in FIG. In other words, Figure 2 is a conceptual side view of the inertia damper.
A housing 3 made of a non-magnetic material is attached by a clamp 2 to the shaft 1 that transmits the driving force of the motor, and a seismic mass made of a magnet etc. is installed inside the housing.
It is sealed with a magnetic fluid 4 surrounding it, and the non-magnetic material 16 is also closed and sealed with an O-ring 7, so there is no oil leakage and the damper effect is high, but it has mass. Since the non-magnetic housing is attached at a large radius from the shaft, the non-magnetic housing itself becomes a load for motor rotation, resulting in excessive starting current, excessive rise time for synchronous motors, or Disadvantages such as reduced efficiency were unavoidable.

This invention was made in view of the above, and its purpose is to:
To provide an assembly using a magnetic fluid that eliminates and improves the above-mentioned drawbacks, has a small load on the inertia damper itself, has an effective buffering effect, and can improve reliability and durability. It's about doing.

(Means for Solving the Problems) Therefore, in an assembly using magnetic fluid according to the present invention, an outer ring is disposed in substantially the same ring shape on the outer periphery of a rotating body, and an annular space is created between the rotating body and the outer ring. At the same time, the annular space is filled with a magnetic fluid, and a predetermined gap communicating with the annular space is provided between the rotating body and the outer ring at positions on both sides of the annular space. A magnet is disposed inside, and the magnetic fluid is held by the magnetic flux within the gap caused by the magnet.

(Function) When the assembly using the magnetic fluid described above is used as an inertia damper, the magnetic fluid acts as a viscous power transfer agent between the rotating body and the outer ring, so it is highly durable and reliable. In addition, the additional mass directly connected to the drive shaft can be minimized, resulting in a low-load inertia damper.

Note that the application of the assembly using the magnetic fluid of the present invention is not limited to inertia dampers, but can also be applied to bearings and the like, as will be described later.

(Example) Next, a specific example of an assembly using a magnetic fluid according to the present invention will be described in detail with reference to the drawings. - An example of application to a damper will be explained.

First, as shown in FIG. 1, a permanent magnet 8 is attached to the drive shaft 1 via a holder 7 as a rotating body so that the magnetic pole direction NS is perpendicular to the axis of the shaft 1. An inertia ring 9 as an outer ring made of a magnetic material is also mounted on the outside of the magnetic material 8 with a predetermined gap therebetween. Thus, the gap between the permanent magnet 8 and the inertial ring 9 is filled with the magnetic fluid 4. Note that 11 indicates an annular space formed between the holder 7 and the inertial body ring 9, and 12 and 12 indicate gaps formed on both sides of the annular space 11 and communicating with the annular space 11, respectively.

The configuration of this embodiment has been described above, and its operation will be explained next.

The shirt 1, which is rotated by a drive device (not shown), rotates together with the holder 7 and the permanent magnet 8, but at this time, friction between the permanent magnet 8 and the magnetic fluid 4, and friction between the magnetic fluid 4 and the inertial ring 9 occur. Due to this friction, the inertia ring 9 rotates at a speed slightly slower than the average rotational speed of the shaft 1. Therefore, when the shaft 1 attempts to rotate faster than the average speed due to uneven rotation of the drive device, the rotational force is attenuated by the friction between the permanent magnet 8 and the magnetic fluid 4. Furthermore, when the shaft l attempts to rotate at a slower rate than the average speed due to uneven rotation of the drive device, the inertia ring 9 is rotating faster than the above rotation, so the rotational force of the inertia ring 9 is permanently transferred through the magnetic fluid 4. This acts as a motion that causes the magnet 8 and therefore the shaft 1 to rotate faster.

As a result of the above, the drive device, and therefore the shaft 1, can be rotated smoothly at a speed as close to the average speed as possible with the unevenness of rotation being reduced.

In this case, the magnetic fluid 4 interposed in the annular space 11 between the permanent magnet 8 and the inertial ring 9 acts as a viscous power transfer agent as described above, and also acts as a lubricant between the two. become.

Thus, the magnetic fluid 4 interposed between the permanent magnet 8 and the inertial ring 9 is held at the illustrated position by the magnetic force of the permanent magnet 8. In this case, the magnetic pole NS of the permanent magnet 8
The lines of magnetic force (broken lines in the figure) that are generated from the magnetic field tend to pass through the magnetic material as much as possible, so the lines of magnetic force are concentrated at both ends of the magnetic fluid 4, that is, at the gap 12, Since a high-density magnetic flux is formed in the magnet, the magnetic fluid is captured by the magnet and is prevented from flowing outside.

FIG. 3 is a partially cutaway conceptual side view showing a second embodiment of the present invention, in which a permanent magnet 8 is attached to the circumference of the shaft 1 via a holder 7, The attachment of the inertia ring 9 with a predetermined gap and the interposition of the magnetic fluid 4 in the annular space 11 are the same as in the previous embodiment, but the magnetic pole NS of the permanent magnet 8 is aligned with the rotation axis of the shaft 1. Magnetic pieces 10a and 10b are attached to both sides of an inertia ring 9, which is attached in parallel and made of a non-magnetic material.

In this embodiment, the lines of magnetic force generated from the magnetic poles NS of the permanent magnet 8 magnetize the magnetic pieces 10a and 10b to create a magnetic closed circuit from the lower end of the magnetic body 10b in the figure to the lower end of the magnetic body 10a in the figure. Become.

Therefore, in this embodiment, the magnetic flux density becomes higher at the ends of the magnetic fluid 4, that is, at the gap 12, 12, and therefore the magnetic fluid's trapping force and retention force become larger.

The partially cutaway conceptual diagram of the side view shown in FIG. 4 is a third embodiment in which the present invention can be carried out, and is shown in FIG. 1 except that the inertial ring 9 is made of a non-magnetic material. The structure is the same as that of the embodiment, and the direction NS of the magnetic pole of the permanent magnet 8 is the same as that of the shaft 1.
In this case, the effect as an inertia damper is obtained in the same manner as explained in FIG. Using the wrapping phenomenon, the gap 1
2.12 to hold the magnetic fluid within.

In each of the above embodiments, the holder 7 is attached around the shaft, and the permanent magnet is attached to the outer periphery of the holder 7, but the invention is not limited to this. It is also possible to implement a structure in which a permanent magnet is attached directly to the inertial body ring, or a permanent magnet may be attached to an inertial body ring.

As mentioned above, the inertia damper of each of the above embodiments is
First, the inertia of the inertia ring is used to accelerate or decelerate the rotation speed of the shaft to make it as uniform as possible due to the friction of the magnetic fluid filled in the gap between it and the shaft, so disk friction Unlike a plate, there is no change in the friction coefficient due to wear of the friction member, no scattering of friction member powder, etc., and there are advantages such as no harm to other systems in the precision machinery system. Furthermore, since the only part directly connected to the shaft 1 is the permanent magnet (although in the above embodiment, the holder 7 is also used) or the permanent magnet is also attached to the inertia ring, the moment of inertia of the directly connected member is reduced. Since it is small and the start-up load on the drive device (motor, etc.) is correspondingly small, a new advantage arises in that the start-up power and the like do not have to become extremely large.

Further, in each of the above embodiments, the magnetic fluid is strongly captured and held by the influence of the magnetic field, and there is little risk of it leaking out, so it is excellent in reliability and durability. In addition, the magnetic fluid forms a film in areas other than the opening of the magnetic fluid, and the thickness of this film becomes uniform as the shaft rotates, so the friction between the magnetic fluid and the inertial ring and the friction between the permanent magnet and the inertial ring are reduced. The damping effect is also uniform on all the circumferential surfaces, so a smooth damping effect can be expected.

Next, an embodiment in which an assembly using a magnetic fluid according to the present invention is applied to a bearing in a radial and/or axial direction will be described with reference to FIGS. 5 to 10.

Fig. 5 is a longitudinal cross-sectional side view of the bearing.
A permanent magnet 2 is attached to an inner ring 22 as a rotating body attached to
3 is attached so that the direction of its magnetic NS is parallel to the axis 21 as shown in the figure, and the outer ring 24 is fitted with the inner ring 22 to which the permanent magnet 23 is attached through a small gap. A magnetic fluid 25 is interposed in the minute gap. In the case of this embodiment, the inner ring 22 and the outer ring 24 are made of non-magnetic material, and the reason why the outer ring 24 is divided into two parts as shown is that the outer ring 24 is separated into two parts as described above. In order to fit the outer ring 24, the outer ring 24 is composed of two parts as shown in the figure, and both parts are fitted to the outside of the inner ring 22 and then fixed. It is. Note that 31 represents an annular space formed between the inner ring 22 and outer ring 24, and 32 and 32 represent gaps that are formed between the inner ring 22 and outer ring 24 and communicate with the annular space 31. .

In this configuration, the lines of magnetic force generated by the permanent magnet are approximately elliptical, regardless of the presence or absence of non-magnetic material, so it can be imagined that magnetic force and lines are generated as shown by the dotted lines in the figure. By the way, the magnetic fluid is strongly attracted by the force of the magnet, so if the permanent magnet 23 is used with an appropriate magnetic strength, the magnetic fluid 2 is attracted as shown in the figure.
5 is held at the position of the gap 32, 32 as shown in the figure, and does not flow out beyond this.

The magnetic fluid held in this position by the attractive force of the permanent magnet 23 has its own considerable pressure, and the inner ring 22 of the bearing to which the permanent magnet 23 is attached is floating in this pressure. Become. Therefore, unlike bearings made of solid materials, a bearing with almost no vibration can be obtained.

Figure 6 is a conceptual longitudinal cross-sectional side view of the bearing portion showing one of the other embodiments. As shown in the same figure, in this embodiment, the inner ring 22 is made of a magnetic material. This shows an example in which a permanent magnet 23 is attached to the inner ring 22 so that its magnetic pole NS is perpendicular to the direction of the axis, and the outer ring 24 is also made of a magnetic material. The arrangement of the magnetic fluid 25 in the annular space 31 between the outer ring 24 and the like is the same as in the fourth embodiment. In this example, the lines of magnetic force are expected to pass through the magnetic material as shown by the dotted line in the same figure and draw a configuration as shown in the dotted line in the figure. It is considered that the magnetic fluid is concentrated in the end portion, that is, in the gap 32, 32, and strongly prevents the magnetic fluid from flowing out from this portion.

Figure 7 is a vertical cross-sectional side conceptual diagram showing the sixth embodiment, however, axis 2
The lower part with 1 as the center appears symmetrically with the upper part, so it has been omitted, but this figure is the same as Fig. 5 except that the shape of the permanent magnet 23 is different from Fig. 5, and its action and effect, lines of magnetic force, etc. The directions and the like are also expected to be the same as in FIG. 5, so their explanation will be omitted.

Figure 8 is a drawing similar to Figure 7 showing the seventh embodiment, but
In this embodiment, the inner ring 22 and the outer ring 24 are made of non-magnetic material, and the structure is similar to that shown in FIGS.
6a and 26b are attached. With this configuration, the magnetic bodies 26a attached to both ends of the permanent magnet 23
, 26b, namely 27a, 27b and 28
Since the magnetic lines of force are concentrated near a and 28b,
This part also attracts the magnetic fluid 25 particularly strongly,
Therefore, it seems to be effective in increasing the pressure of the magnetic fluid inside the bearing.

■Back construction■ Figure 9 is a drawing similar to Figure 7 showing the configuration of the eighth embodiment, in which the inner ring 22 and outer ring 24 are each made of a non-magnetic material, but the permanent magnet 23 has a triangular structure. shall be. The structure of the permanent magnet 23 is thus changed to the end portion 32 of the magnetic fluid 25.
If the permanent magnet is configured to have a protruding shape near 32, the lines of magnetic force of the permanent magnet will be concentrated at high density near the end portion 32.32 of the magnetic fluid. It is also effective for increasing the pressure of the magnetic fluid in the magnetic fluid.

Figure 10 of the first implementation team is similar to Figure 7 showing the ninth embodiment, and is similar to Figure 7 in that the inner ring 22 and outer ring 24 of the bearing are made of non-magnetic material. In the embodiment, the permanent magnet 23 is attached to the outer ring. If the permanent magnet 23 is attached to the outer ring 24 in this way, the shaft 21
The mass of the inner ring 22, which is directly connected to the inner ring 22, is reduced, which has the advantage of reducing the starting load.

In addition to the above, there are also other considerations, such as how to install the permanent magnet, whether the permanent magnet is attached to the inner ring or the outer ring, and whether the inner ring or outer ring is made of magnetic material or non-magnetic material.
It can be designed in various ways depending on the purpose.

As described above, in the fourth to ninth embodiments, the permanent magnet is attached to the inner ring or outer ring of the bearing by interposing a magnetic fluid in the annular space between the outer ring and the inner ring. The magnetic force of the permanent magnet holds the magnetic fluid interposed in the gap between the outer and inner rings of the bearing in that position, generates a considerable pressure, and the inner ring of the bearing floats within that pressure to operate. The bearing is less likely to vibrate in the direction of the shaft, has no oil leakage, and maintains airtightness.

Furthermore, since the structure is simple, it can be precisely processed and failures are reduced.

(Effects of the Invention) The assembly using the magnetic fluid of the present invention is constructed as described above. Therefore, when the assembly using the magnetic fluid of the present invention is applied to an inertia damper,
The inertia damper itself has the advantage of having a small load, yet has an effective buffering effect, and can improve reliability and durability.On the other hand, when the inertia damper itself is applied to a bearing, This has the advantage that the vibration of the shaft caused by this is almost eliminated, and the bearing is airtight and free from oil leakage. In particular, in this assembly, the magnetic fluid in the annular space is held by the magnetic flux generated on both sides of the annular space, so there is no need for a mechanical seal to hold the magnetic fluid. Even when applied to functional parts, the structure is simple and highly durable.

Furthermore, since the magnetic fluid is arranged around the outer periphery of the rotating body, the diameter of the rotating body can be reduced as necessary to reduce its moment of inertia, which has the advantage of improving the responsiveness of the rotating body. There is also.

[Brief explanation of the drawing]

Fig. 1 is a conceptual side view of the present invention implemented as an inertia damper, Fig. 2 is a conceptual side view of a conventional inertia damper, and Fig. 3 is a partially cutaway side view of the inertia damper of the second embodiment. 4 is a conceptual drawing similar to FIG. 3 of the third embodiment, FIG. 5 is a vertical cross-sectional side conceptual diagram when the present invention is implemented as a bearing, and FIG. 6 is a fifth diagram showing the fifth embodiment. 7 is a vertical cross-sectional side view of the vicinity of the bearing showing the sixth embodiment; FIG. 8 is a drawing similar to FIG. 7 showing the seventh embodiment;
FIG. 9 is a drawing similar to FIG. 7 showing the eighth embodiment, and FIG. 10 is a drawing similar to FIG. 7 showing the ninth embodiment. DESCRIPTION OF SYMBOLS 1... Shaft, 4... Magnetic fluid, 7... Holder, 8... Permanent magnet, 9... Inertia ring, 11...
・Annular space, 12... Gap, 21... Bearing, 22.
...Inner ring, 23...Permanent magnet, 24...Outer ring, 25
...Magnetic fluid, 31...Annular space, 32...Gap.

Claims (1)

[Claims] 1. An outer ring is disposed approximately coaxially around the outer circumference of the rotating body, an annular space is formed between the rotating body and the outer ring, and a magnetic fluid is filled in this annular space, and magnetic fluid is placed on both sides of the annular space. At this position, a predetermined gap is provided between the rotating body and the outer ring that communicates with the annular space, and a magnet is placed in the annular space, and the magnetic flux in the gap caused by the magnet causes the magnetic An assembly using a magnetic fluid, characterized in that it is configured to hold a fluid.