JP2014159869A - Rolling bering device - Google Patents

Abstract

Provided is a rolling bearing device that is less likely to seize and has a long life.
An electric compressor includes a substantially cylindrical housing 1, a rotating shaft 2 coaxially arranged inside the housing 1, and rolling bearings 10 and 10 for rotatably supporting the rotating shaft 2 on the housing 1. It is equipped with. One end of the rotating shaft 2 protrudes to the outside from the opening 1 a of the housing 1, and an impeller 3 for compressing air is attached to the end of the rotating shaft 2. Further, a sleeve 8 is press-fitted into the inner peripheral surface of the housing 1, and a rolling bearing 10 is disposed on the radially inner side of the sleeve 8. A radial gap C is provided between the inner peripheral surface of the sleeve 8 and the outer peripheral surface of the outer ring 12 of the rolling bearing 10. The size of the radial gap C is set such that the inclination of the outer ring 12 with respect to the sleeve 8 is 0.0025 rad or less.
[Selection] Figure 2

Description

  The present invention relates to a rolling bearing device.

  A housing, a rotating shaft provided with an impeller at its end, a rolling bearing that rotatably supports the rotating shaft on the housing, a rotor provided on the outer peripheral surface of the rotating shaft, and an inner peripheral surface of the housing; A rolling bearing device including a stator, in which a rotor and a stator are arranged to face each other in a radial direction, is incorporated in, for example, an in-vehicle supercharger or a pneumatic feeder, and is used as an electric compressor or an electric blower (Patent Document) 1).

JP 2002-369474 A

For example, electric compressors (rolling bearing devices) used for in-vehicle turbochargers are generally used at high rotational speeds of tens of thousands to hundreds of thousands of rpm, so slippage occurs between the rolling elements and the raceway surface. As a result, seizure and bearing life may be shortened. Therefore, the rolling bearing device as described above is required to prevent seizure.
SUMMARY OF THE INVENTION The present invention solves the problems of the prior art as described above, and an object of the present invention is to provide a long-life rolling bearing device that is unlikely to cause seizure even when used at a high rotational speed.

  In order to solve the above-described problems, an aspect of the present invention has the following configuration. That is, a rolling bearing device according to an aspect of the present invention includes a housing, a rotary shaft provided with an impeller, and a plurality of rolling elements between an inner ring and an outer ring so as to freely roll, the housing and the rotary shaft A rolling bearing for rotatably supporting the rotating shaft on the housing, a sleeve disposed between the housing and an outer ring of the rolling bearing, and an outer peripheral surface of the rotating shaft. And a stator provided on the inner peripheral surface of the housing so as to face the rotor, a radial clearance is provided between the outer peripheral surface of the outer ring and the inner peripheral surface of the sleeve, The inclination of the outer ring with respect to the sleeve is 0.0025 rad or less.

  In this rolling bearing device, the rolling bearing can be a ball bearing, and the groove radius of the raceway groove provided in the inner ring can be 54% or more and 60% or less of the diameter of the ball that is the rolling element.

  The rolling bearing device of the present invention has a radial clearance between the outer peripheral surface of the outer ring and the inner peripheral surface of the sleeve, and the inclination of the outer ring with respect to the sleeve is 0.0025 rad or less. Seizure hardly occurs and has a long life.

It is sectional drawing which shows the structure of the electric compressor which is one Embodiment of the rolling bearing apparatus which concerns on this invention. It is the fragmentary sectional view which expanded and showed the rolling bearing in FIG. 1, and its peripheral part. It is sectional drawing which shows the structure of a test apparatus. It is sectional drawing which shows the structure of the electric compressor which is the 1st modification of a rolling bearing apparatus. It is sectional drawing which shows the structure of the electric compressor which is the 2nd modification of a rolling bearing apparatus. It is sectional drawing which shows the structure of the electric compressor which is the 3rd modification of a rolling bearing apparatus. It is sectional drawing which shows the structure of the electric compressor which is the 4th modification of a rolling bearing apparatus.

DESCRIPTION OF EMBODIMENTS Embodiments of a rolling bearing device according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing the structure of an electric compressor which is an embodiment of a rolling bearing device according to the present invention. FIG. 2 is an enlarged partial sectional view showing the rolling bearing and its peripheral portion in FIG.
The electric compressor of FIG. 1 includes a substantially cylindrical housing 1, a rotating shaft 2 coaxially arranged inside the housing 1, and a pair of rolling bearings 10 and 10 that rotatably support the rotating shaft 2 in the housing 1. And. As the rolling bearing 10, for example, as shown in FIGS. 1 and 2, an inner ring 11, an outer ring 12, and a plurality of rolling elements (balls) 13 that are arranged to freely roll between the inner ring 11 and the outer ring 12. And an angular ball bearing comprising:

  Note that grease (not shown) is sealed inside the rolling bearing 10 (internal space formed between the outer peripheral surface of the inner ring 11 and the inner peripheral surface of the outer ring 12). The grease lubricates the inner ring 11, the outer ring 12, and the rolling elements 13 of the rolling bearing 10, thereby reducing friction and suppressing seizure. Further, the rolling bearing 10 may be provided with a sealing device as shown in FIG. 1, but may not be provided.

  One end of the rotating shaft 2 (the right end in FIG. 1) protrudes from the opening 1 a of the housing 1 to the outside. An impeller 3 for compressing air (corresponding to an impeller which is a constituent element of the present invention) is attached to an end of the rotating shaft 2 protruding outside the housing 1 by a nut 22. Arranged outside the housing 1. An air supply pipe 23 containing the impeller 3 is integrally formed at the axial end of the housing 1 on the side where the impeller 3 is located (the right end in FIG. 1). ing.

  The opening 1 a is provided with a sealing device (not shown) such as a labyrinth seal or a mechanical seal, and seals between the rotating shaft 2 and the housing 1. In the following, the axial end (the right end in FIG. 1) on the side where the impeller 3 is located among the axial ends of the housing 1 and the rotary shaft 2 is referred to as “impeller side end”. The opposite axial end (the left end in FIG. 1) may be referred to as the “anti-impeller side end”.

  Two rolling bearings 10 are used, and these two rolling bearings 10 and 10 are interposed between the housing 1 and the rotating shaft 2 in a front combination (DF) and are arranged with a space in the axial direction. Has been. As shown in FIG. 2, a sleeve 8, which is a metal cylindrical member, is press-fitted on the inner peripheral surface of the housing 1, and a rolling bearing 10 is disposed on the radially inner side of the sleeve 8. A small radial gap C (hereinafter also referred to as “clearance”) is provided between the inner peripheral surface of the sleeve 8 and the outer peripheral surface of the outer ring 12.

  That is, the two rolling bearings 10 and 10 are arranged between the outer peripheral surface of the rotating shaft 2 and the inner peripheral surface of the sleeve 8, and the respective inner rings 11 and 11 are fixed to the rotating shaft 2 by press fitting or the like. The outer rings 12, 12 are held on the sleeve 8 via a radial gap C. Since the radial gap C is provided between the inner peripheral surface of the sleeve 8 and the outer peripheral surface of the outer ring 12, the outer rings 12, 12 can be displaced in the axial direction.

  The radial clearance C is such that the inclination of the outer ring 12 with respect to the sleeve 8 (hereinafter sometimes referred to as “misalignment”) is 0.0025 rad or less (preferably 0.0020 rad or less). Is set to That is, the size of the radial gap C is set so that the angle formed by the center axis of the sleeve 8 and the center axis of the outer ring 12 is 0.0025 rad or less (preferably 0.0020 rad or less). The axial length of the sleeve 8 is preferably equal to or greater than the width of the outer ring 12. In addition, the thickness of the sleeve 8 is preferably set to a thickness that does not deform due to a radial load acting on the rolling bearing 10.

An inner ring spacer 24 fitted to the outer peripheral surface of the rotary shaft 2 is interposed between the two rolling bearings 10 and 10. And each inner ring | wheel 11, 11 of these rolling bearings 10 and 10 has the inner side surface (side surface which mutually opposes) abuts against the inner ring spacer 24, and the outer side surface (side surface which is not facing the axial direction outer side). The abutting portion is abutted against the side wall 2a of the step portion formed in the vicinity of both end portions of the rotating shaft 2. Thereby, the axial displacement of the inner rings 11, 11 of the two rolling bearings 10, 10 is restricted.
On the other hand, one of the outer rings 12 and 12 of the two rolling bearings 10 and 10 (the outer ring 12 of the left rolling bearing 10 in FIG. 1) is preloaded on the outer side surface (the axially outer side surface that is not opposed). A load spring 21 is abutted, and an axial preload is applied by the preload load spring 21.

  With such a configuration, a preload is applied to the rolling bearing 10 against which the preload load spring 21 is abutted, and the rotary shaft 2 is rotatably supported inside the housing 1 without rattling. When a ball bearing is used as the rolling bearing 10, the preload is applied to accurately position the rolling bearing 10 in the axial direction, suppress the runout of the rotating shaft 2, and suppress the sliding of the rolling element 13. Can do. As a preloading method, a constant pressure preloading method using a preloading spring 21 is preferable. As the preload spring 21, for example, a compression coil spring can be used.

  Furthermore, the electric compressor includes an electric motor including a rotor 5 and a stator 6. A rotor 5 having a field magnet is fixed by an interference fit at an intermediate portion in the axial direction of the outer peripheral surface of the rotary shaft 2 and between the two rolling bearings 10 and 10. A stator 6 is fixed to a portion of the inner peripheral surface of the housing 1 that faces the outer peripheral surface of the rotor 5. The rotor 5 may be a laminated core formed by laminating a plurality of thin magnetic metal plates in the axial direction, and may be configured without a magnet. The type of the stator 6 is not particularly limited. For example, as shown in FIG. 1, the armature coil 6b is wound around a laminated core 6a formed by laminating a plurality of magnetic metal thin plates in the axial direction. The thing comprised by is mentioned.

  When the armature coil 6b is connected to the motor inverter 27 and energized, the rotary shaft 2 is rotationally driven by the electric motor, so that the impeller 3 fixed to the rotary shaft 2 rotates. The air is pumped through the air supply pipe 23 by the rotation of the impeller 3. In the electric compressor of this embodiment, since the rotor 5 and the rolling bearings 10 and 10 are fixed to the rotating shaft 2, the weight is reduced, the size is reduced, the efficiency is increased, and the system is simplified.

  Such an electric compressor of the present embodiment can be used for various purposes for compressing gas, and can be suitably used for, for example, a vehicle-mounted supercharger (electric motor-driven supercharger). Electric compressors used in in-vehicle superchargers are generally used at high rotational speeds of tens of thousands to hundreds of thousands of rpm, so that slippage occurs between the rolling elements and the raceway surface, and seizure is likely to occur. . However, in the electric compressor of this embodiment, the clearance C is provided between the inner peripheral surface of the sleeve 8 and the outer peripheral surface of the outer ring 12 as described above, and the outer ring 12 can be displaced in the axial direction. Therefore, an appropriate preload can be applied to the rolling bearing 10. And since the minimum preload which does not increase the slip between the rolling element 13 and the raceway surface of the inner ring | wheel 11 is provided, slip does not increase and the seizure of the rolling bearing 10 does not arise easily.

  Further, as described above, an appropriate clearance C is provided between the inner peripheral surface of the sleeve 8 and the outer peripheral surface of the outer ring 12, and the inclination of the outer ring 12 with respect to the sleeve 8 is 0.0025 rad or less (preferably 0.0020 rad or less). Therefore, the relative slip which generate | occur | produces between the rolling element 13 which revolves and the track surface of the inner ring | wheel 11 is suppressed. For this reason, seizure hardly occurs between the rolling elements 13 and the raceway surface of the inner ring 11, and therefore the electric compressor of this embodiment does not seize even when used at a high rotational speed of tens of thousands to hundreds of thousands of rpm. It is difficult to occur and has a long life.

  At this time, the seizure can be further suppressed by appropriately setting the groove radius of the raceway surface (the raceway groove) of the inner ring 11 where seizure is likely to occur. That is, the groove radius of the raceway groove provided in the inner ring 11 is preferably 54% or more and 60% or less of the diameter of the ball that is the rolling element 13. With such a configuration, even if the outer ring 12 is inclined (misaligned) with respect to the sleeve 8, the relative slip generated between the revolving rolling element 13 and the raceway surface of the inner ring 11 is suppressed. Since it is easy, the occurrence of seizure can be further suppressed.

  Such a configuration is particularly preferably applied to the rolling bearing 10 (the left-side rolling bearing 10 in FIG. 1) disposed at the end portion on the side opposite to the impeller. The reason is as follows. When the impeller 3 rotates and pumps air, a force in the direction from the end portion on the anti-impeller side toward the end portion on the impeller side (force in the right direction in FIG. 1) acts on the rotary shaft 2. Therefore, in the rolling bearing 10 arranged at the impeller side end, the preload increases with the increase in the rotational speed of the impeller 3, and the slip generated between the revolving rolling element 13 and the raceway surface of the inner ring 11 decreases. On the other hand, since the force does not act on the rolling bearing 10 arranged at the end portion on the side opposite to the impeller, the preload does not increase even if the rotational speed of the impeller 3 increases, and the preload may be too small. . As a result, since the sliding of the rolling bearing 10 disposed at the opposite end portion of the impeller is relatively high, seizure is more likely to occur than the rolling bearing 10 disposed at the end portion of the impeller.

Further, the rolling bearing device having the same configuration as that of the electric compressor of the present embodiment can be used as an electric blower. The electric blower can be used for various applications for sending gas, and can be suitably used for, for example, a pneumatic feeder for a fuel cell and a water vapor pump.
In addition, this embodiment shows an example of this invention and this invention is not limited to this embodiment. For example, in the present embodiment, the two rolling bearings 10 and 10 are a front combination (DF), but may be a rear combination (DB).

  In the present embodiment, an angular ball bearing has been described as an example of a rolling bearing. However, in the present invention, various types of rolling bearings other than the angular ball bearing can be used. For example, radial rolling bearings such as deep groove ball bearings, 4-point contact ball bearings, self-aligning ball bearings, cylindrical roller bearings, tapered roller bearings, needle roller bearings, self-aligning roller bearings, thrust ball bearings, thrust It is a thrust type rolling bearing such as a roller bearing.

Further, when a plurality of rolling bearings are provided as in the present embodiment, one or more types of rolling bearings may be used. And when providing 2 or more types of rolling bearings, the combination of the kind is not specifically limited. Furthermore, the number of the rolling bearings 10 that support the rotating shaft 2 is not particularly limited, and may be one or two or more.
Furthermore, the material of the race rings (inner ring 11 and outer ring 12) of the rolling bearing 10 is not particularly limited, but a metal such as steel is preferable. Specific examples include heat-resistant steel such as M50 (when heat resistance and wear resistance are required), stainless steel such as SUS440C, bearing steel such as SUJ2, and carburized steel.

Further, the material of the rolling element 13 is not particularly limited, but a metal such as steel or ceramic is preferable, and when the rotating shaft 2 is used at a high speed rotation of several tens of thousands to several hundred thousand rpm, the ceramic is more suitable. preferable. Specific examples of the ceramic include silicon nitride (Si ₃ N ₄ ), alumina (Al ₂ O ₃ ), silicon carbide (SiC), zirconia (ZrO ₂ ), aluminum nitride (AlN), and the like.

  In the electric compressor of the present embodiment, since the electric motor is installed inside the housing 2, the temperature of the rolling bearing 10 rises due to the heat generated by the electric motor, and the raceway surface of the rolling bearing 10 and the rolling elements 13. There is a possibility that the oil film existing between the rolling surfaces becomes thin. If a ceramic having a lower density than the bearing steel used in general is used as the material of the rolling element 13, the centrifugal force acting on the rolling element 13 during rotation of the rotating shaft 2 is reduced, and the rolling bearing 10 is loaded. The increase in the calorific value can be suppressed by suppressing the load.

In addition, when the rolling element 13 is made of metal, there is a possibility that wear may occur and seizure may occur. However, if the rolling element 13 is made of ceramic, the wear is suppressed. Further, if the races 11 and 12 are made of steel such as heat-resistant steel and the rolling elements 13 are made of ceramic, the races 11 and 12 and the rolling elements 13 are made of different materials, so the oil film becomes insufficient. However, they are less likely to adhere to each other and have excellent wear resistance and seizure resistance. Therefore, the rolling bearing 10 has a long life, and as a result, the electric compressor has a long life.
In addition, when the gas to be compressed or pumped is high temperature, it is preferable that the races 11 and 12 are made of heat-resistant steel and the rolling element 13 is made of ceramic. There is a risk that a change in preload due to the difference between the two occurs. Therefore, in order to suppress a change in preload due to a difference in linear expansion coefficient, it is preferable to use a constant pressure preload.

  FIG. 4 is a cross-sectional view showing the structure of an electric compressor which is a first modification of the rolling bearing device according to the present invention. In this modification, the rolling is arranged at the end of the impeller side and supports the rotating shaft 2 while supporting the force (the rightward force in FIG. 4) that acts when the impeller 3 rotates and pumps air. The number of bearings 10 is two. Accordingly, the rolling bearing 10 disposed at the end portion on the impeller side increases in preload as the rotational speed of the impeller 3 increases. However, since the force is shared by the two rolling bearings 10 and 10, the rolling element 13 and the raceway It is possible to suppress an increase in surface pressure with the surface, and to prevent generation of noise and a decrease in bearing life.

  FIG. 5 is a cross-sectional view showing the structure of an electric compressor that is a second modification of the rolling bearing device according to the present invention. In this modification, a tandem type double-row angular ball bearing is used as the rolling bearing 10 a that is disposed at the impeller side end and supports the rotating shaft 2. The outer ring 12a of the tandem double-row angular ball bearing has a structure in which double-row outer ring raceway surfaces are integrally provided, and its axial width dimension is larger than that of the single-row angular ball bearing. Therefore, even when the clearance with respect to the sleeve 8 is the same, the inclination (misalignment) of the outer ring 12a can be reduced. Compared with the case where two rolling ball bearings 10 as shown in FIG. 4 are combined, the axial dimension is reduced to make the bearing device compact, or the rolling elements (balls) 13a are enlarged to increase the load capacity. I can do it.

FIG. 6 is a cross-sectional view showing the structure of an electric compressor which is a third modification of the rolling bearing device according to the present invention. In this modification, each rolling bearing 10 is a rear combination (DB), and is disposed at the end portion on the side opposite to the impeller, and supports the force acting when the impeller 3 rotates and pumps air. The number of rolling bearings 10 that support 2 is two.
FIG. 7 is a cross-sectional view showing the structure of an electric compressor which is a fourth modification of the rolling bearing device according to the present invention. In this modification, each rolling bearing is a rear combination (DB) and is disposed at the end portion on the side opposite to the impeller, and supports the rotating shaft 2 while supporting the force acting when the impeller 3 rotates and pumps air. As the rolling bearing 10a that supports the tandem type, a tandem double-row angular ball bearing is used.

〔Example〕
Using the test apparatus shown in FIG. 3, the seizure resistance of the rolling bearing device of the present invention was evaluated. The test apparatus shown in FIG. 3 includes a substantially cylindrical housing 101, a rotating shaft 102 coaxially disposed inside the housing 101, and a pair of rolling bearings 110 and 110 that rotatably support the rotating shaft 102 on the housing 101. It is equipped with. The pair of rolling bearings 110, 110 is a front combination.

  Further, a metal sleeve 108 is press-fitted into the inner peripheral surface of the housing 101, and one rolling bearing 110 (the left bearing in FIG. 3) is arranged inside the sleeve 108, and the other rolling bearing. 110 (the right bearing in FIG. 3) is directly fitted to the inner peripheral surface of the housing 101. A clearance is provided between the inner peripheral surface of the sleeve 108 and the outer peripheral surface of the outer ring of the rolling bearing 110. Further, an axial preload is applied to the outer ring of the rolling bearing 110 (the left bearing in FIG. 3) by a spring 104. The rolling bearings 110 and 110 have an outer diameter of 22 mm, an inner diameter of 8 mm, and an outer ring width of 12 mm (11.5 mm excluding chamfered portions at both ends in the axial direction).

The rotating shaft 102 was rotated at a rotational speed of 100,000 rpm while applying a predetermined radial load, and the time until seizure occurred on the rolling bearing 110 (the left bearing in FIG. 3) was measured. The outer ring temperature was measured, and it was determined that seizure occurred when the temperature increased by 10 ° C. from the temperature at the start of the test. And when it did not generate | occur | produce seizure even if it rotated for 100 hours, it was set as the pass, and when seizure occurred by rotation for less than 100 hours, it was set as the failure.
Table 1 shows the axial load (preload) applied to the rolling bearing 110, the radial load applied to the rotating shaft 102, the inclination of the outer ring with respect to the sleeve 108 (misalignment), and the rotation time until seizure occurs. The misalignment was obtained from the amount of dimensional change in the axial direction of the side surface of the outer ring with respect to the rotating shaft 102.

As can be seen from Table 1, test no. 1 and test no. No. 2 rolling bearing was rejected and test No. with small misalignment was small. 3 and test no. No. 4 rolling bearing was acceptable.
When the misalignment value is large, slippage increases, and seizure is likely to occur due to frictional heat between the rolling elements and the raceway surface of the inner ring. If the preload is increased, the slip will be reduced, but the surface pressure between the rolling elements and the raceway will increase, leading to noise generation and reduced bearing life. It is not preferable to increase the preload (beyond the preload amount that can be obtained).

Next, the relationship between the groove radius of the raceway groove provided in the inner ring and the seizure resistance was examined. That is, rolling bearings with different groove radii provided in the inner ring were prepared, and seizure resistance was evaluated in substantially the same manner as described above using the test apparatus shown in FIG. In these rolling bearings, the diameter of the balls as the rolling elements is the same, and the ratio of the groove radius to the ball diameter ([groove radius] / [groove radius] / [ The diameter of the ball], and hereinafter referred to as “groove curvature ratio”.
Groove curvature ratio, rotational speed of rotating shaft 102, axial load (preload) applied to rolling bearing 110, radial load applied to rotating shaft 102, test environment temperature, inclination of outer ring relative to sleeve 108 (misalignment), and seizure Table 2 shows the rotation time until the occurrence of.

As can be seen from Table 2, the test No. with a small groove curvature ratio was obtained. No. 11 rolling bearing was rejected, test No. with a large groove curvature ratio. 12-15 rolling bearings were acceptable.
If the value of the groove curvature ratio is small, slippage increases and seizure is likely to occur due to frictional heat between the rolling elements and the raceway surface of the inner ring. Also, if the groove curvature ratio is increased, the slip will be reduced, but the surface pressure between the rolling elements and the raceway will increase, leading to noise generation and reduced bearing life. It is not preferable to increase the groove curvature ratio (beyond the preload amount at which rigidity is obtained).

DESCRIPTION OF SYMBOLS 1 Housing 2 Rotating shaft 3 Impeller 5 Rotor 6 Stator 8 Sleeve 10, 10a Rolling bearing 11, 11a Inner ring 12, 12a Outer ring 13, 13a Rolling element C Clearance

Claims (2)

  A plurality of rolling elements are rotatably provided between a housing, a rotating shaft provided with an impeller, and an inner ring and an outer ring, and the rotating shaft is disposed between the housing and the rotating shaft. A rolling bearing that is rotatably supported; a sleeve that is disposed between the housing and an outer ring of the rolling bearing; a rotor that is provided on an outer peripheral surface of the rotating shaft; and a housing that is opposed to the rotor. A stator provided on the inner peripheral surface, a radial clearance is provided between the outer peripheral surface of the outer ring and the inner peripheral surface of the sleeve, and the inclination of the outer ring with respect to the sleeve is 0.0025 rad or less. A rolling bearing device characterized by.   2. The rolling bearing device according to claim 1, wherein the rolling bearing is a ball bearing, and a groove radius of a raceway groove included in the inner ring is 54% or more and 60% or less of a diameter of the ball as the rolling element. .

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