JPS60501122A - Improved magnetic seal assembly - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Improved magnetic seal assembly Technical field TECHNICAL FIELD This invention relates to methods of sealing holes, and more particularly to ferrofluidic seals. Improved features of the present invention The main application example of magnetic seals is the Winchester disk drive (Winche Ste? -diskdrive) A complete seal of the rotating shaft within the device body.

Background technique Regarding effectively sealing the penetration point of a high-speed rotating shaft that is penetrated by a hole in the main body. Many problems are arising. These issues are important in recent data processing applications, especially in Wi-Fi. This can be seen most clearly in Chester disk drive devices. winchester data record Disks are easily contaminated by debris that has entered the disk chamber, and this contamination can cause data loss. Errors may occur during data recording and reading, leading to unexpected results. Ru. Therefore, it is possible to prevent the entry of scorching debris into the disc chamber. It is important to do so.

The point where contamination occurs is the rotating spindle shaft that penetrates into the disk chamber through the basic body. It's nearby. Although it is necessary to form a hole for the shaft to pass through, it is necessary to prevent the intrusion of debris. It is often difficult to seal this hole due to the Different parts of shaft circumferential bearings, etc. Pollution occurs indoors along the axis from Traditionally, there is a method to properly seal this hole. A law is proposed.

Some methods utilized in the prior art include sliding contact with surfaces such as rubber washers. These include controlling clearances, pressurizing chambers, and using fluid pumps. by the surface Sliding contact is difficult to apply to high-precision data processing because uneven friction causes multiple positional errors. Not applicable to the field. Furthermore, the sealing material produces debris due to wear. I wonder Machining techniques have been established that can create clearances narrow enough to prevent the intrusion of debris. Clearance control is also not available. Even small pieces can cause contamination. Cause. Indoor pressurization requires continuous power and there is a possibility of equipment failure. Ru. Fluid pump seals in hydrodynamic systems prevent fluid drift and contamination. It has been found that it cannot be used.

The only significant conventional method of sealing holes around rotating shafts is ferrofluid, Chirp using ferromagnetic fluid or magnetic liquid. − In the type of equipment, debris The material that seals the hole to prevent intrusion must be a magnetic fluid or ferromagnetic fluid. the Ferrofluids are highly sensitive materials that are permanently magnetized in a fluid carrier (vehicle) such as mineral oil. It is a stable dispersion of microscopically small particles.

A sealing method using magnetic fluid is Machine Design N magnetic flow seal (Magne tic-F'luid 5eal's)".

U.S. patents granted to U.S. patents that partially utilize ferrofluid as part of the shaft liquid seal. 4. x7x, sls and F D, Ezek US Pat. No. 4,293,137, issued to J. These etc. 's patent describes different ways in which magnetic fluid seals prevent debris from passing around the rotating shaft. It is listed.

A disadvantage with traditional ferrofluid seals is that the ferrofluid is typically in direct contact with the shaft. The problem is that it creeps along the shaft and causes direct contamination. The creep mentioned above is This ultimately results in loss of ferrofluid and compromises the integrity of the seal. Conventional technology Another disadvantage of many methods is that the axis itself is not a return path for the magnetic flux due to the magnetic field. It must be made of magnetic material. As a result, lightweight materials such as aluminum Therefore, efficient materials cannot be used. In addition, another drawback is that the magnetic Field strength is inherently subject to spatial limitations. As a result, the functionality of the magnetic fluid decreases. , which further shortens the life of the seal.

Both prior art methods provide an effective encapsulation effect and a rotation axis regardless of the material. It has not been possible to provide a long-life seal around the perimeter. Therefore, the area of ferrofluid It has high strength and can completely prevent the magnetic fluid from creeping along the magnetic fluid axis. A magnetic seal assembly is required.

Therefore, it is an object of the present invention to prevent the magnetic fluid from creeping along its axis.

An object of the present invention is to provide an improved magnetic seal assembly.

Another object of the invention is to increase the magnetic field strength of ferrofluids without changing the magnet material. It is an object of the present invention to provide a magnetic seal assembly that adds

A further object of the invention is to prevent ferrofluid leakage due to mechanical shock or other physical factors. It is an object of the present invention to provide a magnetic seal assembly with reduced possibility.

The present invention is an improved ferrofluidic seal assembly particularly for use around rotating shafts. Ru. In particular, the present invention provides a method for attaching the spindle shaft to the main body of the Winchester disk drive device. Intended for use in penetrating locations.

Briefly, the preferred embodiment of the invention includes an inner magnetic link concentrically coupled to the shaft. The inner magnetic ring is surrounded by a uniform air carrier between the inner magnetic ring and the inner magnetic ring. an outer magnetic ring with an air gap that prevents air or debris from passing through. improved magnetic properties, including an arbitrary amount of magnetic fluid disposed in the air gap, such as A fluid seal assembly. The inner and outer magnetic rings are permanently magnetized members. on the other hand , a magnetic gas is a suspension of permanently magnetized particles in a fluid carrier. inner and outer magnetic The direction of polarization in the ring is parallel to the axis of the shaft, but at least In the vicinity of the cap, the two rings are opposed to each other.

In a preferred embodiment, the magnetic ring has a coplanar iron plate to increase the magnetic field strength. It has fragments made of In addition, the inner and outer magnetic rings are designed so that the magnetic fluid is attached to the shaft or body. surface magnetism, as well as a protective ring that prevents debris from moving along the surface. be converted into

An advantage of the present invention is that the magnetic fluid does not directly contact the shaft and that the magnetic fluid does not come into direct contact with the shaft and The goal is to prevent flops.

Another advantage of the present invention is that the opposing polarization of the inner ring and outer ring allows air cap The magnetic fluid strength is increased at the ends and the integrity of the magnetic fluid is maintained. .

Another advantage of the invention is that the magnetic protection rings on the surfaces of the inner and outer ring magnets It is possible to prevent any movement of magnetic fluid to the shaft or body.

Yet another advantage of the present invention is that the ferrofluidic seal assembly has a shaft and It can be used with the main body.

Still another advantage of the present invention is that the ferrofluid in the seal has an increased air gap. The seal is maintained at a lower temperature, which extends the life of the seal.

The above-mentioned and other objects and advantages of the present invention are as follows: It will be obvious to a person skilled in the art from the description of the form and industrial applicability of It will become a thing.

FIG. 1 shows a state in which a rotating shaft is mounted through a hole in a main body, and is related to the present invention. Perspective view of the improved magnetic seal assembly: FIG. 2 is a cross-sectional view taken along line 2-2 in FIG. 1; and FIG. 3 is a cross-sectional view of the protective ring and FIG. 3 is a schematic plan view of a magnetic seal assembly showing polarization of other magnetic elements;

The best mode for carrying out the invention is an improved magnetic fluid seal assembly. , particularly characterized by concentric oppositely magnetized magnets and a ferrofluid seal between them. can be attached. This ferrofluidic seal specifically provides sealing of the hole between the rotating shaft and the body applied to. The primary application of this improved seal is Winchestudy. The present invention relates to a spindle shaft that is inserted into the main body of a disk drive device.

A preferred embodiment of the improved magnetic seal assembly is illustrated in FIG. Indicated by number 10. The seal assembly 10 includes a hole 14 in the base body 16. It is typically found in spindle shafts that pass through the disk chamber of rotating equipment.

This improved magnetic fluid seal assembly 10 includes an inner magnetic ring 18 and a concentric ring. Includes an outer magnetic ring 20.

The outer magnetic ring 20 has a uniform air carrier between the inner magnetic ring 18 and their sides. They are arranged concentrically with the tops 22. This air cap 22 is A magnetic fluid 24 is inserted to prevent passage between the two, thereby sealing the space.

The structure of this improved magnetic fluid assembly 10 is shown in cross-section in FIG. Ru. Inner magnetic ring 18 is shown coupled to shaft 12 . Similarly outer magnetic Ring 20 is coupled to body 16. In this case both bonds are connected to rings 18 and and 20, respectively, must be strong enough to hold them in place. Also, that The bond forms a perfect seal at the interface to prevent objects or debris from entering. It must be.

Since the inner magnetic ring 18 is securely connected to the rotating shaft 12, it rotates with the rotating shaft. Turn around. Therefore, this inner magnetic ring 18 does not impair the rotational state of the shaft 12. Therefore, the balance of the surroundings must be carefully considered.

In addition, in FIG. 2, the inner magnetic ring 18 and the outer magnetic ring 20 have a predetermined thickness. An air cap 22 is formed in the total thickness direction of both rings. Furthermore, magnetic The fluid 24 is formed only at both ends of the air gap 22 due to the magnetism and magnetic field, and is not formed in the center. It is not usually found in the area.

Figure 2 also illustrates the direction of magnetization of the magnetic rings 18 and 20. as shown Both magnetic rings are polarized parallel to the axial direction of the rotating shaft 12. however , the inner magnetic ring 18 is polarized in the opposite direction to the outer magnetic ring. In Figure 2 The inner magnetic ring 18 is polarized in the S direction, while the outer ring is polarized in the N direction. However, both directions can be reversed without changing the effect.

Opposing magnetization of the inner and outer magnetic rings 18 and 20 This polarization produces an additional effect near the ends of air gap 22. This collection of magnetic fields The inside acts to retain the magnetic fluid 24 within its vicinity. The stronger the magnetic field, the more magnetic The integrity of the fluid 24 is increased and the ferrofluid can leak through the air gap 22. It gets lower. Therefore, this opposing polarization arrangement of the magnetic rings results in the separation of the individual magnetic rings. The magnetic field strength of the ferromagnetic fluid 24 can be increased without increasing the magnetic field.

As shown in FIG. 2, the magnetic field strength is is increased by adding a pair of ferromagnetic pole pieces 26 on the side and bottom coplanar ends. be concentrated. These pole pieces 26 are usually made of soft iron or magnetic steel and contain magnetic particles. It acts as a magnetic conductor and magnetic concentrator to increase the integrity of the fluid distribution 24. talented , the magnetic pole piece 26 strongly adheres or couples the inner magnetic ring 18 and the outer magnetic ring 20. be done. ′ FIG. 3 outlines a further improved method of the preferred embodiment. In the figure, the magnetic The air seal assembly 10 is attached to various portions of the inner magnetic ring 18 and the outer magnetic ring 20. It has magnetic poles. Here, the inner magnetic ring 18 is shown including the inner protective ring 28. The unilateral magnetic ring 20 is shown including an outer protective ring 30. inside The protective ring 28 and the outer protective ring 30 usually have magnetic components on the surfaces of the rings 18 and 20. It is a polarized ring and is polarized in the opposite direction to the rest of rings 18 and 20.

Typically this is surface magnetization only. As a result of applying these protective rings 28 and 30, Magnetic fluid 24 leaks through air gap 22 and creeps onto shaft 12 or body 16. Prevent it from happening. Typically, the protective rings 28 and 30 are fixed to the assembly 10. Recommended for chamber side only. However, similar protection is required to prevent loss of magnetic fluid. Preferably, a protective ring is also provided on the external surface.

The inner magnetic ring 18 and outer magnetic ring 20 of the preferred embodiment are of suitable magnetic properties. Can be formed from materials. Due to the concentration of magnetic field caused by this, only a weak magnetic field is generated, Spatial array materials are available to which high-precision machining techniques can be applied. Usually this is what you want The material used is strontium ferrite embedded in a nylon matrix. There is something.

Pole piece 26H is a magnetic conductor that acts as a magnetic concentrator and is generally made of soft iron or magnetic steel. is formed. This pole piece 26 is located at the axis of the inner magnetic ring 18 and the outer magnetic ring 20. It is formed in accordance with the surface of the direction. They are less magnetic fluids or ferromagnetic fluids. The body 24 is selected from a fluid carrier in which solid particles, which are magnetic materials, are extremely finely dispersed. determined. For optimal results, this fluid should have very finely dispersed permanent magnetization. The particles that contain the particles are selected. Also, the particles may coagulate or solidify within the fluid. A fluid such as mineral oil is selected to prevent this. In this way, the magnetic current Even if the liquid part of the body 24 does not have magnetism, the entire magnetic fluid 24 can flow as if it were Works as a magnetic material.

A suitable commercially available ferromagnetic fluid 24 can be used as the magnetic fluid. .

The dimensions of the various components of improved magnetic seal assembly 10 are nearly arbitrary. Inside The magnetic fields of the side magnetic ring 18 and the outer magnetic ring 20 have a slight influence on their ring radius. Therefore, choose a ring that is large enough to generate an appropriate magnetic field. is preferred. In the figures, the air gap 22 is shown to have the intended size. However, this is for illustrative purposes only. In fact, bubble wrap is It needs to be as narrow as possible to maintain a strong magnetic field. normal air gap The dimensions are approximately 5. OX 10-5 meters to 7.5X10-’ meters (0, 002-0,003”).The extremely narrow air gap prevents magnetic fields and magnetic flows. Debris large enough to destroy the body is prevented from entering the air gap 22. Yoshi A large splinter tool will only destroy the ferrofluid 24 at one end of the air gap 22, but not the other end. It is considered that the magnetic fluid 24 is not damaged.

One advantage of the arrangement of magnetic materials in the present invention is that the magnetic field strength is comparable to that of conventional seals. This is achieved by using an arbitrarily wide air gap 22.

Also, the wider the air gaps 2, 2, the more generated in the magnetic fluid 24 due to the rotation of the shaft. The fact that frictional heat is lower may be necessary for some applications. Ma The reduction in frictional heat is effective in reducing the amount of fluid loss due to evaporation, and therefore the seal assembly 1 0's effective lifespan is extended. This reduction in shear strain is negligible when using this seal. A related factor is that the physical life of the motor exceeds 50,000 hours.

Except for the surface magnetization of the inner protective ring 28 and the outer ring 30, the inner magnetic ring 1 8 and outer magnetic ring 20 are uniformly polarized. Balanced symmetry with uniform polarization The magnetic field is effective in maintaining the continuity and integrity of the seal.

In this case, the inner magnetic ring 18 has a balanced symmetrical ring shape for proper rotation. However, the outer ring 20 does not meet such requirements in its external dimensions. It should be clearly stated that there is no. The inner end of the outer magnetic ring 20 is the inner ring 1 8 in a concentric circle with an appropriate air gap 22 between them. If so, the outer ring 18 has the external shape necessary to fit into the hole in the body 16. There are no restrictions that prevent it.

The materials of the shaft 12 and the body 16 are arbitrary. A magnetic fluid 24 connects the inner ring 18 and the outer ring. Since it does not come into contact with any member other than the ring 20, the selection of the other b material is a matter of the present invention. It is unrelated to the operation.

Although the present invention has been described above with reference to the application of rotary shafts, this type of circular There is no need to limit inventions related to tools. The magnetic fluid according to the invention is It can be used in applications with an intervening air gap.

In particular, it is useful in applications with members that move relative to each other. Main departure Another typical use of magnetic seals by Akira is to attach them to each other along an air cap. This is an example of an application with two coplanar members moving in opposite directions. Also, front and rear The change in motion is similar to that of the rotation motion described above. The magnetic seal of the present invention is as described above. In the case of a linear air cap, as in the case of a radial air gap, Industrial applicability that can be used in sufficient quantities even if An improved magnetic seal assembly according to the present invention requires a seal to prevent the passage of objects. It can be adapted to any application that provides an air cap that The present invention is particularly suitable for holes in the main body. It is applied to applications that provide a rotating shaft that is penetrated by the shaft. Special applications of the improved invention is the insertion part of the main shaft into the disk chamber of the Winchester disk drive device. be.

The present invention is easy to manufacture and is compatible with Winchester disk drive devices. It can be installed immediately.

The invention also provides a rotating shaft that requires insertion into a tightly sealed chamber. It can also be readily installed in other applications. The incorporation of the seal according to the invention is , there is no need to change the structure of other parts of this data processing device.

The improved magnetorheological seal according to the present invention can It is formed. Therefore, it can be economically produced and also advantageously used economically. . Therefore, the present invention has industrial applicability, particularly in the data processing field. You can expect to do so.

Engraving (no changes to the content) FIG+ Procedural amendment (formality) %formula% 1. Display of the incident Showa year application no. Improved magnetic seal assembly 3. Person who makes corrections Relationship to the incident: Patent applicant ´International search report

Claims (1)

[Claims] 1. an inner magnetic ring that is concentrically connected to the shaft and rotates with the shaft; , the outer part of the inner magnetic ring is magnetically polarized along a direction parallel to the axis of rotation of the shaft. With the inner ring: an outer magnetic ring coupled to a main body having an insertion hole and fixed together with the main body; , the outer ring includes a cylindrical hole passing through its interior, the cylindrical hole being The inner ring is concentric with the ring and a gap is formed between the inner rings. The inner part of the outer ring has a larger radius and the inner part of the outer ring is opposite to the direction of polarization of the inner ring. With an outer ring magnetically polarized along the direction: It is sealed in and near the gap between the inner ring and outer ring, and is stimulated by magnetic force. The insertion hole in the main body containing an arbitrary amount of ferromagnetic fluid is held in the vicinity of the rotating shaft. Improved magnetic seal assembly that seals around the perimeter. 2. In the magnetic seal assembly according to claim 1, A magnetic seal assembly, wherein the air gap is configured to have a minimum tolerance. 3. In the magnetic seal assembly according to claim 1, the ferromagnetic fluid is contained in the fluid carrier. A magnetic seal assembly containing multiple microparticles of ferromagnetic material in a stable dispersion state. 4. In the magnetic seal assembly according to claim 1, Coupling in the same plane of at least one of the inner magnetic ring and the outer magnetic ring A magnetic seal assembly further comprising a magnetic conductor pole piece. 5. In the magnetic seal assembly according to claim 1, A magnetic protection ring portion is provided on the surface of the inner magnetic ring, and the magnetic protection ring The polarity of the inner magnetic ring is such that the movement of the ferromagnetic fluid is hindered through this The polarity of the magnetic seal assembly is opposite to that of the rest of the magnetic seal assembly. 6. The magnetic seal assembly according to claim 5, wherein the magnetic protection ring portion is Provided on the surface of the outer magnetic ring, the polarity of the magnetic protection ring is determined through this. The polarity of the remainder of the outer magnetic ring is such that the movement of the ferromagnetic fluid is obstructed. Magnetic seal assembly which is the opposite. 7. The magnetic seal assembly according to claim 6, wherein the inner magnetic ring and the outer magnetic ring further comprising a magnetic conductor magnetic piece coupled to the same plane of at least one of the side magnetic rings. magnetic seal assembly. 8. In the magnetic seal assembly according to claim 7, the air gap has a minimum allowable error. The ferrofluid is set to have ferromagnetic properties in a stable dispersion within the vehicle. A magnetic seal assembly containing multiple microparticles of material. 9. A direction extending along one side of the gap and perpendicular to the plane containing the edge of the gap a first magnetic element that can be magnetically polarized along; Sky! extending from the first magnetic element along the other side or side of the a second magnetic element; distributed throughout the gap to prevent the movement of substances through the gap; The air gap is equipped with a magnetic fluid that is dispersed to prevent the movement of substances through the narrow air gap. Magnetic seal assembly to seal.