JP2002372051A - Rolling bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rolling bearing device with a long service life restrained from wear and seizure even when moisture and foreign matters intrude into a rolling bearing. SOLUTION: A steam force-feeder is provided with a housing 2, a rotating shaft 1 insert-fitted to the housing 2, and angular ball bearings 4, 5 interposed between the housing 2 and the rotating shaft 1 to rotatably support the housing 2 and the rotating shaft 1. An opening part 2a for communicating the inside and outside of the housing 2 is provided at the end part of the housing 2, and a ball 40 provided at the angular ball bearing 4 disposed in a closest position to the opening part 2a is formed of ceramic.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling bearing device, and more particularly to a rolling bearing suitably used for a steam pump or a compressor device for a fuel cell, a dental handpiece, a lathe for a machine tool, a grinding machine, and the like. Related to the device.

[0002]

2. Description of the Related Art A rolling bearing device including a housing, a shaft inserted into the housing, and a rolling bearing for supporting the housing and the shaft so as to be rotatable relative to each other is known as a fuel cell, a dental handpiece, and a machine tool. It is used for various devices such as machines. For example, a fuel cell may use a rolling bearing device such as an air supply device that pumps air to a cathode or a steam pump that pumps very high-temperature steam.

[0003] The fuel cell depends on the electrolyte used, such as a solid polymer type, a solid electrolyte type, a phosphoric acid type, a molten carbonate type,
Each type of fuel cell is classified as an alkaline type or the like, and each type of fuel cell has a cell in which both surfaces of an electrolyte plate or an electrolyte membrane are sandwiched between cathode (oxygen electrode) and anode (fuel electrode) electrodes as one cell. A plurality of cells are stacked in multiple layers via a separator to form a stack. Then, oxygen in the air is supplied to the cathode side as an oxidant gas, and hydrogen is supplied to the anode side as a fuel gas.

[0004] Such a fuel cell is provided with an air supply device for supplying air to the cathode side by pressure. The air supply device includes a turbocharger system in which a compressor is driven by an exhaust gas turbine, and a compressor in which a motor is used. There is a motor driving method for driving. Further, when supplying oxygen and hydrogen to the fuel cell for reaction, depending on the type of the fuel cell (for example, solid polymer type), it is necessary to add water vapor for the reaction. Further, for example, when gasoline is used as fuel, very high temperature steam is required. Therefore, a steam pump may be required to increase the energy efficiency of the fuel cell.

[0005] The rotating shaft of the compressor or the steam pump as described above is rotatably supported by the housing by a lubricated rolling bearing. As a lubrication method for the rolling bearing, oil lubrication or grease lubrication is employed depending on the use of the fuel cell. For example, oil fuel lubrication is not suitable, and grease lubrication is preferable since reduction in weight and simplification of the system are required for fuel cell systems for automobiles. This is because in the case of oil lubrication, a system for supplying lubricating oil to the inside of the rolling bearing is required, which is contrary to the above requirement.

Further, if the lubrication system of the impeller supporting rolling bearing of the compressor or the steam pump is oil lubrication, the lubricating oil passes through a seal portion located between the impeller and the impeller supporting rolling bearing to remove lubricating oil. Grease lubrication is preferred because of the problem of mixing with water and steam.

[0007]

However, in a steam pump, when the space behind the impeller changes from a negative pressure to a positive pressure, steam may enter the rolling bearing. If a contact-type seal is used for a sealing device provided at an opening of the housing to seal between the housing and the rotating shaft, heat generation becomes a problem when the rotating shaft to which the impeller is connected rotates at high speed. Devices often employ non-contact seals. However, when the sealing device is a non-contact type seal, the space between the housing and the rotating shaft is not completely sealed, and the inside and the outside of the housing are slightly communicated with each other. There's a problem.

[0008] The race and the rolling element of the rolling bearing are EHL
The rolling and sliding motion is performed through the oil film. However, if steam enters the rolling bearing and mixes with the grease, the EHL oil film is extremely difficult to be formed. Also, when the rotating shaft to which the impeller is connected rotates at high speed, the heat generated by sliding friction at that time causes the EHL oil film to be further thinned. Is likely to occur, which may result in seizure. As a result, the life of the rolling bearing device is greatly reduced.

On the other hand, in a dental handpiece or a machine tool, a tool for processing or a work which is a workpiece is fixed to a tip of a rotating shaft, and water or cutting fluid is used for processing. Cutting powder, polishing powder, etc. are generated. Therefore, if the sealing device provided at the opening of the housing and seals between the housing and the rotating shaft is a non-contact type seal,
As described above, the space between the housing and the rotating shaft is not completely sealed, and the inside and the outside of the housing are slightly communicated with each other, so that foreign matters such as water, cutting fluid, cutting powder, and abrasive powder are not sealed. There is a risk of passing through the device and entering the inside of the rolling bearing.

Then, the EH is placed between the race and the rolling element.
The L oil film is difficult to be formed, and there is a possibility that foreign matter may be caught. As a result, the life of the rolling bearing device is greatly reduced. Accordingly, the present invention has been made to solve the above-mentioned problems of the prior art, and to provide a long-life rolling bearing device in which abrasion and seizing hardly occur even when moisture or foreign matter enters the inside of the rolling bearing. And

[0011]

In order to solve the above problems, the present invention has the following arrangement. That is, the rolling bearing device of the present invention includes a housing, a shaft inserted into the housing, and a rolling interposed between the housing and the shaft to support the housing and the shaft so as to be relatively rotatable. And a bearing having an opening at an end of the housing for communicating between the inside and the outside of the housing, wherein the rolling bearing provided at a position closest to the opening is provided. At least a part of the moving body is made of ceramic.

With this configuration, even if moisture enters the inside of the rolling bearing through the opening and the thickness of the oil film is reduced due to the incorporation of moisture into the grease, the race of the rolling bearing and the raceway of the rolling bearing can be reduced. Lubricity between the rolling elements is not significantly impaired, and wear and seizure hardly occur. Further, even if foreign matter enters the inside of the rolling bearing from the opening, the foreign matter is hardly caught. Therefore, the rolling bearing device has a long life.

Further, since the rolling elements made of ceramic have a low density and a small centrifugal force, the rotational torque of the rolling bearing is small. Further, since the hardness of the ceramic is high, the contact area between the rolling element and the raceway surface of the race is small. Therefore, heat generation due to rotation is small, and an oil film is easily formed between the bearing ring and the rolling element. Further, since an oil film is easily formed, it is also advantageous against foreign matter intrusion.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a rolling bearing device according to the present invention will be described with reference to the drawings. [First Embodiment] FIG. 1 is a longitudinal sectional view showing a structure of a steam pump for a fuel cell which is a first embodiment of a rolling bearing device according to the present invention.

The rotating shaft 1 is inserted into the housing 2, and both ends of the rotating shaft 1 protrude from openings 2 a and 2 b at both ends of the housing 2. At one end (the left end in FIG. 1) of the rotating shaft 1, an impeller 13 for feeding steam is attached by a nut 14.
Are arranged outside the housing 2. An air supply pipe 16 in which the impeller 13 is provided is attached to an end of the end of the housing 2 on the side where the impeller 13 is located (the left end in FIG. 1).
By the rotation of 3, the steam is pressure-fed in the air supply pipe 16.

A housing lid 10 is attached to the end of the housing 2 opposite to the side where the impeller 13 is located (the right end in FIG. 1).
The opening 2b is formed in the housing lid 10. The rotating shaft 1 is provided between the rotating shaft 1 and the housing 2.
The housing 2 is rotatably supported by the angular ball bearings 4 and 5. These angular ball bearings 4 and 5 are fitted on the outer peripheral surface of the rotating shaft 1 and the inner peripheral surface of the housing 2 so that the respective inner rings 4a and 5a are fixed to the rotating shaft 1, and the respective outer rings 4b and 5b are fixed. It is fixed to the housing 2.

Between the two angular ball bearings 4 and 5,
An inner race spacer 11 fitted to the outer peripheral surface of the rotating shaft 1 and an outer race spacer 12 fitted to the inner peripheral surface of the housing 2 are interposed. The inner race spacer 11 contacts the inner races 4a and 5a, Outer ring spacer 1
Reference numeral 2 is in contact with the outer rings 4b and 5b. Also, the openings 2a,
2b are each provided with a sealing device,
And the housing 2 are sealed. A labyrinth seal 6 is provided in the opening 2a on the side where the impeller 13 is attached.
Is provided, and a mechanical seal 7 is provided in the opening 2b opposite to the side where the impeller 13 is attached. Since the labyrinth seal 6 is a non-contact type sealing device, the space between the rotating shaft 1 and the housing 2 is not completely sealed and has a slight gap. Therefore, the inside and the outside of the housing 2 communicate with each other. On the other hand,
Since the mechanical seal 7 is a contact-type sealing device, the space between the rotating shaft 1 and the housing 2 is completely sealed.
The inside and outside of the housing 2 do not communicate with each other.

Of the two angular ball bearings 4 and 5,
Closest to the opening 2a provided with the virulence seal 6
The angular ball bearing 4 disposed at the position includes an inner ring 4a and
Outer ring 4b is made of stainless steel (SUS440C)
The ball 4c is made of ceramic (Si _ThreeN_Four)
You. On the other hand, the angular ball bearing 5 includes an inner ring 5a, an outer ring 5
Both b and ball 5c are made of stainless steel (SUS440C).
Has been established. Thus, the inner races 4a, 5a and the outer race 4
Since both b and 5b are made of stainless steel,
Nos. 4 and 5 have excellent corrosion resistance. In addition, both bearings 4 and 5
The outer ring guide type polyimide resin cages 4d and 5d
It is grease lubricated. In addition, back assembly
Nut 15 fixed position on both bearings 4 and 5
Preload is being applied.

Such a water vapor pumping device is provided with an impeller 1 by rotating a rotating shaft 1 with an electric motor (not shown).
Rotate 3 to pump water vapor. Since the pressure inside the housing 2 becomes a negative pressure during rotation and a positive pressure during a stop, if the rotation and the stop are repeated, the pressure inside the housing 2 will be a negative pressure and a positive pressure. The labyrinth seal 6 is provided in the opening 2a on the side where the impeller 13 is attached to prevent the invasion of water vapor. However, since it is a non-contact type sealing device to prevent heat generation due to friction, the inside of the housing 2 When the pressure changes from the negative pressure to the positive pressure, the water vapor near the impeller 13 enters the inside of the housing 2 and further enters the inside of the angular ball bearing 4.

As a result, moisture is mixed into the grease sealed in the angular contact ball bearing 4 and
When the rotation of the wheel is suddenly accelerated, the inner and outer wheels 4a, 4b and the ball 4c
The ability to form an oil film in the area of contact with the film decreases. When the ball 4c is made of metal, there is a high possibility that abrasion occurs early and seizure occurs. However, the wear is suppressed because the ball 4c is made of ceramic. In addition, since the inner and outer rings 4a, 4b and the ball 4c are made of different materials, adhesion between the inner and outer rings 4a and 4b is hardly generated, and wear resistance and
Excellent seizure resistance. Therefore, the angular contact ball bearing 4
Has a long life, and thus the steam pump has a long life.

Although the effect of extending the life can be obtained by making a part of the plurality of balls 4c of the angular ball bearing 4 made of ceramic, it is most preferable to make all of them made of ceramic. In the present embodiment, an electric motor is used to drive the steam pump, and a contact-type sealing device is used for the opening 2b on the electric motor side.
If a non-contact type sealing device is used for the opening 2b, air may enter, so the ball 5c of the angular ball bearing 5 disposed closest to the opening 2b is made of ceramic. Is preferred.

In the case where the water vapor containing hydrogen is fed under pressure, if there is a danger of fuel cell efficiency drop or explosion, etc., a magnetic coupling is adopted as the coupling to completely seal the rolling bearing device. Then, intrusion of the atmosphere may be prevented. [Second Embodiment] FIG. 2 is a longitudinal sectional view showing the structure of a dental handpiece which is a second embodiment of the rolling bearing device according to the present invention. In FIG. 2,
The same or corresponding parts as those in FIG. 1 are denoted by the same reference numerals as those in FIG.

The rotary shaft 1 is inserted into a cylindrical housing 2 having one end closed, and an end of the rotary shaft 1 protrudes from an opening 2 a of the housing 2. The rotating shaft 1 is rotatably supported by the housing 2 by two small-diameter ball bearings 4 and 5 interposed between the rotating shaft 1 and the housing 2. The small-diameter ball bearings 4 and 5 are fitted on the outer peripheral surface of the rotating shaft 1 and the inner peripheral surface of the housing 2 to form respective inner rings 4a and 5a.
Are fixed to the rotating shaft 1, and the respective outer rings 4 b, 5 b are fixed to the housing 2.

At the center of the rotating shaft 1, small-diameter ball bearings 4, 5 are provided.
The turbine blades 20 are mounted between them. Further, between the turbine blade 20 and the two small-diameter ball bearings 4 and 5, an inner race spacer 11 fitted on the outer peripheral surface of the rotary shaft 1,
A tool 21 for machining teeth is attached to an end of the rotating shaft 1 protruding from an opening 2a of the housing 2 in contact with the inner races 4a, 5a. In addition, a labyrinth seal 6 is provided in the opening 2 a to seal the space between the rotating shaft 1 and the housing 2. Since the labyrinth seal 6 is a non-contact type sealing device, the space between the rotating shaft 1 and the housing 2 is not completely sealed and has a slight gap. Therefore, the inside and the outside of the housing 2 communicate with each other.

Among the two small-diameter ball bearings 4 and 5, the small-diameter ball bearing 4 disposed closest to the opening 2a provided with the labyrinth seal 6 has an inner ring 4a and an outer ring 4b made of stainless steel (SUS440C). ), And the ball 4c is made of ceramic (Si ₃ N ₄ ). On the other hand, in the small-diameter ball bearing 5, the inner ring 5a, the outer ring 5b, and the ball 5c are all made of stainless steel (SUS440C). Since the inner rings 4a, 5a and the outer rings 4b, 5b are made of stainless steel, the bearings 4 and 5 have excellent corrosion resistance.

Although the small-diameter ball bearings 4 and 5 are lubricated with grease, the harm is extremely small in consideration of the influence on the human body. For example, poly-α-olefin or ISO standard VG32,
It is desirable to use grease using liquid paraffin such as VG68 as a base oil. Further, the small-diameter ball bearings 4 and 5
Shield plates 4e and 5e are provided. Further, the nut 15 and the preload load spring 26
The preload is applied to both bearings 4 and 5 at a fixed position. further,
The outer ring 4b, which is a fixed ring, is supported by an O-ring 23 so that the small-diameter ball bearing 4 is prevented from vibrating due to unbalance or external force.

In such a dental handpiece, the rotary shaft 1 rotates by introducing air from a driving air inlet 24 provided in the housing 2 and blowing the air onto the turbine blade 20. The drive of the rotating shaft 1 is not limited to such an air turbine system, but may be a system using a coupling mechanism such as a coupling or a system using an electric motor.

When the tooth is machined by rotating the tool 21, water is used, and cutting powder, abrasive powder and the like are generated. The opening 2a is provided with a labyrinth seal 6 for preventing water and foreign matter from entering. However, since it is a non-contact type sealing device for preventing heat generation due to friction, water and foreign matter (cutting powder, abrasive powder) are prevented. There is a risk of passing through the labyrinth seal 6 and entering the housing 2 and further into the small-diameter ball bearing 4. Then, an oil film may not be easily formed between the inner and outer rings 4a, 4b and the ball 4c, or there is a possibility that foreign matter may be caught. However, since the ball 4c is made of ceramic, such a problem hardly occurs. As a result, the dental handpiece has a long life.

Further, since the fixed-position preload is applied so that the two small-diameter ball bearings 4 and 5 are combined on the back side, when an axial load, which is a stress from the tool 21 during processing, is applied, the tool The load received by the small-diameter ball bearing 4 close to 21 may increase, and the small-diameter ball bearing 4 may have poor lubrication.
However, since the ball 4c of the small-diameter ball bearing 4 is made of ceramic, such a problem hardly occurs. That is, wear of the small-diameter ball bearing 4 is suppressed, and the dental handpiece has a long life.

[Third Embodiment] FIG. 3 is a longitudinal sectional view showing the structure of a machine tool spindle which is a third embodiment of the rolling bearing device according to the present invention. In FIG. 3, the same or corresponding parts as those in FIG. 1 are denoted by the same reference numerals as those in FIG. The rotating shaft 1 is inserted into the housing 2,
Both ends of the rotating shaft 1 protrude from the openings 2a and 2b at both ends of the housing 2. Housing lids 10 are attached to both ends of the housing 2, and openings 2 a and 2 b are formed in the housing lids 10.

The rotating shaft 1 is rotatable on the housing 2 by four angular ball bearings 4, 4, 4, and 4 and a cylindrical roller bearing 5 interposed between the rotating shaft 1 and the housing 2. Supported. Angular contact ball bearings 4,4
4 and 4 and the cylindrical roller bearing 5 are fitted on the outer peripheral surface of the rotating shaft 1 and the inner peripheral surface of the housing 2 to form the respective inner races 4a, 4a.
4a, 4a, 4a, 5a are fixed to the rotating shaft 1, and the respective outer races 4b, 4b, 4b, 4b, 5b are
It is fixed to.

Between the four angular ball bearings 4, 4, 4, 4, there are three inner race spacers 11, 11, 11 fitted on the outer peripheral surface of the rotating shaft 1 and the inner peripheral surface of the housing 2. Three fitted outer ring spacers 12, 12, 12 are interposed, the inner ring spacer 11 is in contact with the inner ring 4a, and the outer ring spacer 12 is connected to the outer ring 4b.
Is in contact with At the front end (left end in FIG. 1) of the rotating shaft 1, a processing tool or a work (neither is shown) is attached. Further, a sealing device is provided in each of the openings 2a and 2b to seal the space between the rotating shaft 1 and the housing 2. Each of the sealing devices is a labyrinth seal 6 which is a non-contact type sealing device. Therefore, the space between the rotating shaft 1 and the housing 2 is not completely sealed but has a slight gap, and the inside and the outside of the housing 2 communicate with each other.

Opening 2a of the four angular ball bearings 4, 4, 4, 4 on the side where a tool or work is attached
The inner ring 4a and the outer ring 4b are made of stainless steel (S).
US440C), and the ball 4c is made of ceramic (Si
₃ N ₄ ). On the other hand, the other angular ball bearings 4, 4, 4 and the cylindrical roller bearing 5 have inner rings 4a, 5
a, the outer races 4b and 5b and the balls 4c and 5c are both made of stainless steel (SUS440C). Since the inner rings 4a, 5a and the outer rings 4b, 5b are made of stainless steel, the bearings 4 and 5 have excellent corrosion resistance.

All bearings 4 and 5 have cages 4d and 5d made of polyimide resin of an outer ring guide type, and are grease-lubricated. When machining a work using such a machine tool spindle as a machine tool lathe or grinder, a cutting fluid is used.
Grinding powder is generated. The opening 2a is provided with a labyrinth seal 6 for preventing cutting fluid and foreign matter from entering.
Since a non-contact type sealing device is used to prevent heat generation due to friction, cutting fluid and foreign matter (cutting powder, abrasive powder) pass through the labyrinth seal 6 into the housing 2 and further into the forefront angular ball bearing 4. There is a risk of intrusion. Then, an oil film may not be easily formed between the inner and outer rings 4a and 4b and the ball 4c, and there is a possibility that foreign matter may be caught.
Since the ball 4c is made of ceramic, such a problem hardly occurs, and as a result, the spindle for the machine tool has a long life.

In the third embodiment, of the four angular ball bearings 4, 4, 4, and 4, only the ball 4 of the angular ball bearing 4 disposed closest to the opening 2a.
Although c is made of ceramic, if all the balls of the bearings provided from the center of the rotating shaft 1 to the end on the side of the opening 2a are made of ceramic, the life of the rolling bearing device becomes longer. preferable.

Further, a non-contact type sealing device is provided at both of the openings 2a and 2b of the housing 2, and when water or foreign matter may enter from both, the opening 2a may be used.
It is preferable that not only the bearing arranged at the position closest to a, but also the rolling elements of the bearing arranged at the position closest to the opening 2b be made of ceramic. The first to third embodiments described above are examples of the present invention, and the present invention is not limited to the above embodiments.

For example, the seeds of the ceramic constituting the rolling element
Classes include silicon nitride (Si_ThreeN _Four), Other than alumina
(Al_TwoO_Three), Silicon carbide (SiC), zirconia
(ZrO_Two), Aluminum nitride (AlN) etc. can be used
Noh. Also, the rolling shaft provided in the rolling bearing device
To prevent the lubricant from leaking out,
Rotation of shafts, especially impellers, tools, etc.
On the side where the member that converts the
Provide a sealing device in the opening as in each embodiment
Is desirable. For example, in the first embodiment, steam
Since it is not desirable that the lubricant is mixed in the
It is preferable to provide a sealing device at a.

However, if there is no problem with the member that converts the rotation of the shaft into a predetermined work even if the lubricant of the rolling bearing leaks out, for example, in the case of the machine tool spindle of the third embodiment For example, the sealing device may not be provided in the opening 2a. If the opening 2a is not provided with a sealing device, the amount of foreign matter that enters the inside of the housing 2 from the opening 2a increases, but if the ball 4c of the small-diameter ball bearing 4 is made of ceramic, the above-described problem occurs. That is suppressed.

Further, in each of the embodiments, a steam pump, a compressor, a dental handpiece, and a spindle for a machine tool have been described as examples of the rolling bearing device, but the present invention is not limited thereto. Can be applied to Furthermore, in each of the embodiments, a rolling bearing device of a type in which a shaft rotates is described. However, it is needless to say that the present invention is applicable to a rolling bearing device of a type in which a housing rotates.

Further, the type of the rolling bearing provided in the rolling bearing device of the present invention is not particularly limited.
For example, deep groove ball bearings, angular ball bearings, four-point contact ball bearings, cylindrical roller bearings, tapered roller bearings, needle roller bearings,
Radial rolling bearings such as self-aligning roller bearings, and thrust rolling bearings such as thrust ball bearings and thrust roller bearings. When a plurality of rolling bearings are provided, one or two or more rolling bearings may be used. When two or more types of rolling bearings are provided, the combination of the types is not particularly limited.

Furthermore, the number of rolling bearings supporting the shaft is not particularly limited, and may be one or two or more. Furthermore, the method of lubricating the rolling bearing is not particularly limited. For example, in a fuel cell system mounted on an automobile as in the first embodiment, reduction in weight and simplification of the system are required. Therefore, grease lubrication is preferable. Further, if oil lubrication is used, lubricating oil may be mixed into the compressed air or steam from the labyrinth seal 6. For example, in the case of a steam pumping machine as in the first embodiment or a dental handpiece as in the second embodiment, Grease lubrication is desirable for equipment that requires minimum mixing of the lubricant component into the pressure-feeding medium. Oil lubricant lubrication, lubrication lubrication, or forced lubrication may be used when the lubricant is allowed to be mixed into the pumping medium or when lubrication may be insufficient with grease lubrication.

Further, the type of grease for lubricating the rolling bearing is not particularly limited. However, when water is expected to enter as in the first embodiment, for example, the thickener is based on diurea. The oil is poly-α-olefin oil (PA
O) or grease in which the thickener is lithium soap and the base oil is mineral oil to which a rust inhibitor has been added is preferable.

Further, when there is a high possibility of contact with steam or water as in the first and second embodiments, the race of the rolling bearing is made of SUS44 to improve rust resistance.
0C, but usually, stainless steel,
It may be made of any material such as bearing steel such as SUJ2, heat-resistant steel such as M50 (when heat resistance and wear resistance are required), carburized steel, and ceramic materials. In addition, nitriding treatment and rolling treatment are applied to the raceway surface of the rolling bearing arranged closest to the opening provided with the non-contact type sealing device.
It is very preferable to improve the wear resistance by applying a surface treatment such as ceramic film spraying or DLC (diamond-like carbon).

Further, the material of the cage provided in the rolling bearing is not particularly limited, and brass, iron and the like can be used in addition to the polyimide resin. Regarding the guide type of the cage, any of the outer ring guide, the inner ring guide, and the ball guide may be used without any problem. Furthermore, the operating conditions of the rolling bearing device of the present invention, such as the operating speed, the applied load, and the ambient temperature, are not particularly limited.
The present invention exhibits a particularly prolonged service life under conditions where an oil film is difficult to be formed, such as high-speed rotation, high load, and high temperature.

Furthermore, when a ball bearing is used as the rolling bearing provided in the rolling bearing device, it is possible to precisely position the bearing in the axial direction by applying a preload, suppress the shaft runout, and suppress the ball from slipping. it can. As a method of applying a preload, a fixed position preload method is suitable for applications requiring rigidity, and a constant pressure preload method using a spring or the like is suitable for applications requiring high speed. Also, as the preload direction, a back-to-back combination, which has a large acting point distance on the shaft and excellent load capacity against moment load, is more suitable, but if assembly of a rolling bearing device is required, a front-to-back combination is adopted. can do.

[0046]

As described above, in the rolling bearing device of the present invention, the rolling bearing disposed closest to the opening communicating between the inside and the outside of the housing includes the ceramic rolling element. Therefore, even if moisture or foreign matter enters the inside of the rolling bearing, wear and seizure hardly occur, and the life is long.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a first embodiment of a rolling bearing device according to the present invention.

FIG. 2 is a longitudinal sectional view showing a second embodiment of the rolling bearing device according to the present invention.

FIG. 3 is a longitudinal sectional view showing a third embodiment of the rolling bearing device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotation shaft 2 Housing 2a Opening 4 Rolling bearing 4c Ball (rolling element)

Continued on the front page (72) Inventor Hirotoshi Aramaki 1-5-50 Kugenuma Shinmei, Fujisawa-shi, Kanagawa F-term in NSK Ltd. (Reference) 3J101 AA02 AA13 AA43 EA41 FA31 GA31 GA60

Claims (1)

[Claims] 1. A housing, a shaft inserted into the housing, and a rolling bearing interposed between the housing and the shaft to rotatably support the housing and the shaft. And a rolling bearing device having an opening at an end of the housing for communicating the inside and the outside of the housing, wherein at least one of rolling elements provided in a rolling bearing disposed closest to the opening. A rolling bearing device characterized in that the part is made of ceramic.