JP2013139842A - Main motor bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a main motor bearing that can extend a grease life.SOLUTION: A main motor bearing 90 for a railway vehicle supports a main motor spindle on a member disposed so as to face the outer peripheral surface of a main spindle, a main spindle being rotatably supported about the axis. The main motor bearing 90 includes: an outer ring 91 having an outer ring rolling surface 91a provided on the inner peripheral surface thereof; an inner ring 92 having an inner ring rolling surface 92a on the outer peripheral surface thereof and disposed on the inside of the outer ring 91 so that the inner ring rolling surface 92a faces the outer ring rolling surface 91a; rolling bodies 93 which are in contact with both the outer ring rolling surface 91a and the inner ring rolling surface 92a and which are arranged side-by-side on the annular path; and a retainer 94 which retains the rolling bodies 93 at a predetermined pitch in the circumferential direction. The rolling bodies 93 are ceramic balls. The retainer 94 consists of a resin.

Description

  The present invention relates to a bearing for a main motor, and more particularly to a bearing for a main motor capable of extending a grease life while suppressing an increase in manufacturing cost and occurrence of fretting. is there.

  In a bearing for a main motor of a railway vehicle, a ball bearing is used as a fixed-side bearing to cope with expansion and contraction in the axial direction of the main shaft caused by a temperature change, while a main shaft is used as a free-side bearing. Cylindrical roller bearings that can cope with the expansion and contraction of are used. The ball bearing on the fixed side is, for example, a deep groove ball bearing, and includes a steel ball and an iron plate corrugated cage. The free-side cylindrical roller bearing includes a steel cylindrical roller and a brass punched cage. When these main motor bearings are used under high temperature and high speed rotation, for example, grease having lithium soap and mineral oil is used as the lubricating oil.

  Since the lubrication life of grease in the main motor bearings of railway vehicles is shorter than the rolling fatigue life of the bearings, refilling of grease is currently performed in vehicle disassembly inspections that are carried out every predetermined travel distance. In many cases, the deterioration of the grease is progressing even in the current maintenance cycle, and it is necessary to extend the lubrication life of the grease in order to further extend the maintenance cycle. On the other hand, a bearing having a structure capable of easily supplying grease has been proposed as a bearing capable of improving durability (see, for example, Patent Document 1).

JP 2000-291667 A

  The above-mentioned deterioration of grease is mainly due to the temperature rise of the bearing due to heat generated during high-speed rotation of the main motor, and metal wear powder generated by friction of rolling elements and cages made of steel mixed in the grease. doing. Therefore, from the viewpoint of further extending the maintenance cycle, it is required to extend the lubrication life of the grease by suppressing the temperature rise of the bearing and the increase of the metal component in the grease.

  Further, in the conventional main motor bearing, since the race members such as the outer ring and the inner ring and the rolling elements are made of the same material (steel), for example, when the main motor is separated from the railway vehicle and transported alone. However, there is a problem that fretting wear occurs at the contact portions between the raceways of the inner ring and the outer ring and the rolling elements. In addition, since these bearings are subjected to insulation treatment by ceramic spraying to prevent electrolytic corrosion, there is a problem that the manufacturing cost of the bearings increases.

  The present invention has been made in view of the above problems, and an object thereof is to provide a bearing for a main motor capable of extending a grease life while suppressing an increase in manufacturing cost and occurrence of fretting. It is.

  The main motor bearing according to the present invention is a main motor bearing for a main motor of a railway vehicle that supports a main shaft rotatably around a shaft with respect to a member disposed opposite to the outer peripheral surface of the main shaft. The main motor bearing has an outer ring rolling surface on the inner circumferential surface, an outer ring made of steel, and an inner ring rolling surface on the outer circumferential surface, so that the inner ring rolling surface faces the outer ring rolling surface. An inner ring made of steel, an inner ring made of steel, a plurality of rolling elements arranged in contact with the outer ring rolling surface and the inner ring rolling surface, arranged side by side on an annular track, and a predetermined number of rolling elements in the circumferential direction. And a cage for holding at a pitch. The rolling element is a ceramic ball. The cage is made of resin.

  Since the bearing for a main motor of the present invention includes a rolling element that is a ceramic ball, the temperature rise of the bearing during operation of the main motor is suppressed. In addition, since the insulation of the bearing is ensured without subjecting the outer ring or the inner ring to an insulation treatment, the manufacturing cost can be reduced. In addition, since the main motor bearing of the present invention includes a cage made of resin, it suppresses generation of metal wear powder due to friction between the cage and the rolling element, which is a problem in a bearing having a cage made of metal. can do. In the main motor bearing of the present invention, since the rolling element, the inner ring, and the outer ring are made of different materials, the occurrence of fretting at the contact portion between the raceway surface of the inner ring and the outer ring and the rolling element is suppressed. be able to. As described above, according to the main motor bearing according to the present invention, it is possible to provide a main motor bearing capable of extending the life of grease while suppressing an increase in manufacturing cost and occurrence of fretting. .

  The main motor bearing may be an open type bearing. This facilitates the supply of grease to the main motor bearing, and as a result, lubrication of the main motor bearing is facilitated. Here, the open type bearing means a bearing that does not have a seal member that closes a space between the outer ring and the inner ring.

  In the main motor bearing, the cage is made of resin, and the thickness of the cage is increased from the viewpoint of securing the strength and rigidity. For this reason, the space between the outer ring and the inner ring is narrow, and when the space is closed by the seal member, it is difficult to retain sufficient grease in the space. Therefore, in such a main motor bearing, it is preferable to use an open type bearing from the viewpoint of smooth lubrication.

  In the above main motor bearing, the rolling element may be made of silicon nitride. As described above, silicon nitride having excellent rolling fatigue life can be used as a material constituting the rolling element under the usage environment of the bearing that supports the main shaft of the main motor.

  In the above main motor bearing, the cage may be made of a polyamide resin. As described above, a polyamide resin having excellent durability can be used as the material constituting the cage.

  The main motor bearing may be a deep groove ball bearing. Thus, a deep groove ball bearing with a small rolling resistance can be adopted as the main motor bearing.

  The main motor bearing may be a main motor bearing that supports the free side of the main shaft. As described above, the main motor bearing, which is a ball bearing having a rolling resistance smaller than that of the cylindrical roller bearing, can be adopted as the main motor bearing that supports the free side of the main shaft.

  As is apparent from the above description, according to the main motor bearing of the present invention, there is provided a main motor bearing capable of extending the life of grease while suppressing an increase in manufacturing cost and occurrence of fretting. be able to.

It is the schematic which shows the structure of a trolley partially. It is the schematic which shows the structure of a main motor. It is the schematic which expands and shows the structure of a main motor. It is the schematic which expands and shows the structure of a main motor. It is the schematic which shows the structure of the bearing for main motors. It is a flowchart which shows the manufacturing method of the bearing for main motors roughly. It is a flowchart which shows the manufacturing method of the bearing for main motors roughly. It is a figure which shows the relationship between the rotational speed of a main motor, and the temperature rise of the bearing for main motors. It is a figure which shows the relationship between the dmn value of a main motor, the lubrication life (left axis), and the lubrication life ratio (right axis) of grease. It is a figure which shows the result of a fine abrasion test at the time of using a silicon nitride ball | bowl and SUJ2 ball | bowl. It is a figure which shows the contrast of the iron content contained in the grease at the time of using a resin holder and an iron plate holder.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

  First, the structure of the cart of this Embodiment is demonstrated. A cart 1 of the present embodiment is a cart provided in a railway vehicle, and includes a cart body 2, a main motor 10, a coupling 30, a drive device 40, an axle 50, wheels 60, and an axle bearing device. 70.

  The main motor 10 is supported by the carriage body 2 at the main motor mounting portion 2a. The main shaft 20 of the main motor 10 is connected to the drive device 40 via the coupling 30. The drive device 40 has a small gear 41 fixed to the main shaft 20 and a large gear 42 fixed to the axle 50, and the small gear 41 and the large gear 42 are arranged to mesh with each other. A pair of wheels 60 is fixed to the axle 50, and both ends thereof are supported by the axle body 2 by the axle bearing device 70. Further, the axle bearing device 70 is supported by the carriage body 2 in the carriage 2b.

  Next, operation | movement of the wheel 60 by the main electric motor 10 of this Embodiment is demonstrated. Referring to FIG. 1, first, main shaft 20 is rotated by operating main motor 10. At this time, the rotation of the main shaft 20 is transmitted to the driving device 40 via the coupling 30, and the small gear 41 fixed to the main shaft 20 rotates. The rotation of the small gear 41 causes the large gear 42 that meshes with the small gear 41 to rotate. When the axle 50 fixed to the large gear 42 rotates, the wheels 60 fixed to both ends of the axle 50 rotate, and the carriage 1 travels. The operation of the main motor 10 will be described later.

  Next, the configuration of the main motor 10 of the present embodiment will be described. Referring to FIG. 2, main motor 10 is disposed so as to surround stator 12 having coil 12 a, rotor 13 disposed to face stator 12, and stator 12 and rotor 13. The frame 11 is mainly provided. The main shaft 20 is fixed so as to penetrate through a portion including the central portion (rotating shaft) of the rotor 13. The main motor 10 is a first main motor main shaft support structure according to the present embodiment in which the main shaft 20 is rotatably supported around a shaft with respect to a member disposed facing the outer peripheral surface 20a of the main shaft 20. A bearing device 80 and a second bearing device 81 are further provided.

  Next, the operation of the main motor 10 of the present embodiment will be described. With reference to FIG. 2, first, a three-phase alternating current is supplied to the coil 12 a of the stator 12. At this time, a rotating magnetic field is formed around the rotor 13, and an induced current is generated in the rotor 13 by the rotating magnetic field. In this way, a rotating magnetic field is formed around the rotor 13 and an induced current is generated in the rotor 13, thereby generating an electromagnetic force that works to rotate the rotor 13 around the rotation axis. 13 rotates. Then, the rotation of the rotor 13 is extracted to the outside through the main shaft 20.

  Next, the support structure for the main motor spindle of the present embodiment will be described. Referring to FIG. 2, the main motor main shaft support structure of the present embodiment includes a first bearing device 80 that supports the fixed side of main shaft 20 and a second bearing device 81 that supports the free side of main shaft 20. I have. Referring to FIG. 3, the first bearing device 80 includes a first bearing 82, a housing 83 as a first fixing member, a front lid 84, and an end lid 85. The first bearing 82 includes an outer ring 82a, an inner ring 82b, rolling elements 82c, and a cage 82d. The first bearing 82 is sandwiched between the front lid 84 and the end lid 85, the inner circumferential surface of the inner ring 82 b is in contact with the outer circumferential surface 20 a of the main shaft 20, and the outer circumferential surface of the outer ring 82 a is fixed to the housing 83. ing. The first bearing 82 is a main motor bearing of the present embodiment, for example, a deep groove ball bearing.

  Referring to FIG. 4, the second bearing device 81 includes a second bearing 86, a housing 83 as a second fixing member, a front lid 84, and an end lid 85. The second bearing 86 has an outer ring 86a, an inner ring 86b, a rolling element 86c, and a cage 86d. The second bearing 86 is sandwiched between the front lid 84 and the end lid 85, and is disposed so that the inner circumferential surface of the inner ring 86 b is in contact with the outer circumferential surface 20 a of the main shaft 20. Similarly to the first bearing 82, the second bearing 86 is a main motor bearing of the present embodiment, and is, for example, a deep groove ball bearing.

  The outer ring 86 a of the second bearing 86 faces the housing 83 with a displacement allowing member 87 that allows the outer ring 86 a of the second bearing 86 to be displaced relative to the housing 83 in the axial direction of the main shaft 20. Has been placed. More specifically, the displacement permissible member 87 is a member that allows the outer ring 86a of the second bearing 86 to slide relative to the housing 83. For example, a resin is disposed on the inner peripheral surface of a cylindrical member made of metal. Is a plain bearing.

  Next, the main motor bearing 90 of the present embodiment will be described. As shown in FIGS. 3 and 4, the main motor bearing 90 is a member for the main motor 10 of a railway vehicle, in which the main shaft 20 is disposed opposite to the outer peripheral surface 20 a of the main shaft 20, for example, a housing 83. A bearing for a main motor that is rotatably supported around an axis, for example, a deep groove ball bearing having a low rolling resistance.

  Referring to FIG. 5, a main motor bearing 90 includes an outer ring 91 having an outer ring rolling surface 91 a on an inner circumferential surface, an inner ring 92 having an inner ring rolling surface 92 a on an outer circumferential surface, a plurality of rolling elements 93, and And a retainer 94. The inner ring 92 is disposed on the inner side of the outer ring 91 such that the inner ring rolling surface 92 a faces the outer ring rolling surface 91 a of the outer ring 91. The outer ring 91 and the inner ring 92 are made of steel, for example, high carbon chromium bearing steel such as JIS standard SUJ2, alloy steel for machine structure such as SCM420, or carbon steel for machine structure such as S53C.

The rolling elements 93 are, for example, ceramic balls made of Si ₃ N ₄ (silicon nitride), which are in contact with the outer ring rolling surface 91a and the inner ring rolling surface 92a, and are formed on the outer ring rolling surface 91a and the inner ring rolling surface 92a. A plurality are arranged side by side on an annular track along the circumferential direction. The cage 94 is made of a polyamide resin having excellent durability, such as nylon, and holds the rolling elements 93 at a predetermined pitch in the circumferential direction.

  Thus, since the main motor bearing 90 according to the present embodiment includes the rolling elements 93 that are ceramic balls, the temperature rise of the bearing during operation of the main motor is suppressed. Further, since the insulation of the bearing is ensured without subjecting the outer ring 91 and the inner ring 92 to an insulating treatment, the manufacturing cost can be reduced. In addition, since the main motor bearing 90 includes the cage 94 made of resin, it suppresses the generation of metal wear powder due to friction between the cage and the rolling element, which is a problem in a bearing having a cage made of metal. be able to. In the main motor bearing 90, since the rolling element 93, the inner ring 92, and the outer ring 91 are made of different materials, the inner ring rolling surface 92a, the outer ring rolling surface 91a of the inner ring 92 and the outer ring 91, and the rolling element. The occurrence of fretting at the contact portion with 93 can be suppressed. As described above, the main motor bearing 90 of the present embodiment is a main motor bearing capable of extending the life of grease while suppressing an increase in manufacturing cost and occurrence of fretting.

  Further, as shown in FIG. 5, the main motor bearing 90 may be an open type bearing in which the space between the outer ring 91 and the inner ring 92 is not closed by a seal member or the like. This facilitates the supply of grease to the main motor bearing 90, and as a result, lubrication of the main motor bearing 90 is facilitated.

  Further, in the main motor bearing 90, the cage 94 is made of resin, and the thickness of the cage 94 is increased from the viewpoint of securing its strength and rigidity. Therefore, the space sandwiched between the outer ring 91 and the inner ring 92 is narrow, and when the space is closed by the seal member, it is difficult to retain sufficient grease in the space. Therefore, in such a main motor bearing 90, it is preferable to use an open type bearing from the viewpoint of smooth lubrication.

In addition, as described above, in the main motor bearing 90, the material constituting the rolling element 93 is Si ₃ N ₄ (silicon nitride) which has an excellent rolling fatigue life in a use environment as a bearing for supporting the main shaft of the main motor. However, the present invention is not limited to this. That is, the rolling element 93 may be a ceramic ball made of, for example, Zr (zirconia) or Al ₂ O ₃ (alumina).

  Further, the main motor bearing 90 may support the free side of the main shaft 20 as described in the main motor main shaft support structure of the present embodiment. As described above, the main motor bearing 90 that is a ball bearing having a rolling resistance smaller than that of the cylindrical roller bearing can be adopted as the main motor bearing that supports the free side of the main shaft.

Next, a method for manufacturing the main motor bearing of the present embodiment will be described. In the main motor bearing manufacturing method according to the present embodiment, the main motor bearing 90 of the present embodiment can be manufactured. Referring to FIG. 6, in the method for manufacturing a main motor bearing according to the present embodiment, first, a step of manufacturing rolling elements (S10), and a step of manufacturing track members such as outer rings and inner rings (S20), And the step of manufacturing the cage (S30). And the bearing 90 for main motors is manufactured by implementing the process (S40) which combines the outer ring | wheel and inner ring | wheel manufactured in the said process (S10)-(S30), a rolling element, and a holder | retainer. Further, in the step (S10) of manufacturing the rolling element, for example, as described below, a rolling element made of, for example, Si ₃ N ₄ (silicon nitride) is manufactured.

Referring to FIG. 7, first, as a step (S11), a step of preparing a raw material powder made of, for example, Si ₃ N ₄ (silicon nitride) is performed. Next, a mixing step is performed as a step (S12). In this step (S12), a sintering aid is added to and mixed with the Si ₃ N ₄ (silicon nitride) powder prepared in step (S11). This step (S12) may be omitted when no sintering aid is added.

  Next, a molding process is performed as a process (S13). In this step (S13), the raw material powder or a mixture of the raw material powder and the sintering aid is formed into a schematic shape of the rolling element. Specifically, for example, a molded body in which the raw material powder or a mixture of the raw material powder and the sintering aid is molded into the approximate shape of the rolling element by a molding technique such as press molding, cast molding, extrusion molding, rolling granulation, or the like. Is produced.

  Next, a sintering step is performed as a step (S14). In this step (S40), the molded body is sintered to produce a sintered body. Specifically, the molded body is heated by a heating method such as heat heating, electromagnetic wave heating using microwaves or millimeter waves in an atmosphere of an inert gas such as helium, neon, argon and nitrogen. As a result, a sintered body having a schematic shape of the rolling element is produced.

Next, a finishing step is performed as a step (S15). In this step (S15), the surface of the sintered body is processed, and the region including this surface is removed. By performing the steps (S10) to (S15), a rolling element made of Si ₃ N ₄ is manufactured.

  First, a test for confirming the effect of the present invention was performed with respect to suppression of temperature rise during rotation of the bearing. First, a bearing having rolling elements that are steel balls and ceramic balls was prepared. Then, the temperature rise of the outer ring when these bearings were operated at a predetermined rotational speed was investigated. Based on the results of this investigation, the relationship between the temperature increase of the outer ring and the lubrication life of the grease was also considered.

FIG. 8 is a diagram showing the relationship between the rotational speed and dmn value of the bearing and the temperature rise of the outer ring of the bearing. Here, the dmn value is a value indicating the product of the ball rotation diameter of the bearing and the rotation speed of the bearing. FIG. 9 shows the lubrication life of the grease (left axis) calculated from the Boser's equation using the bearing dmn value and the outer ring temperature value of the bearing, and the grease life when ceramic balls and steel balls are used. It is a figure which shows the relationship with lubrication life ratio. As shown in FIG. 8, when the dmn value was 65 × 10 ⁴ and the ceramic ball was used, the temperature increase of the outer ring was smaller by about 8 ° C. than when the steel ball was used. Further, as shown in FIG. 9, at a dmn value of 65 × 10 ⁴ , the lubrication life of grease when using ceramic balls was estimated to be about 1.5 times that when using steel balls. As a result, it has been clarified that the use of a bearing having a rolling element that is a ceramic ball suppresses an increase in temperature during rotation of the bearing, and as a result, the life of the grease can be extended.

Next, an experiment for confirming the effect of the present invention was performed regarding the suppression of the occurrence of fretting. First, Si ₃ N ₄ (silicon nitride) balls and SUJ2 balls were prepared. Then, a fine wear test was conducted in which the Si ₃ N ₄ (silicon nitride) ball and the SUJ2 ball were brought into contact with the vibrating plate to investigate the wear depth of the plate. The test conditions were as follows. The ball size was 5/16. A plate made of SUJ2 was used. The test load was 19.6 kN. At this time, the maximum contact surface pressures between the Si ₃ N ₄ ball and the SUJ2 ball and the plate were 1640 MPa and 1460 MPa, respectively. The amplitude was 0.47 mm. The vibration (frequency) number was 30 Hz. The number of loads was 8.6 × 10 ⁵ times. The test time was 8 hours. Also, no lubricating oil was used.

FIG. 10 is a diagram showing the results of a fine wear test in the case of using Si ₃ N ₄ (silicon nitride) balls and SUJ2 balls. As is clear from FIG. 10, the maximum wear depth of the plate was smaller in the Si ₃ N ₄ (silicon nitride) ball than in the SUJ2 ball. Accordingly, in a bearing having an outer ring or an inner ring made of metal such as SUJ2, a rolling element that is a ceramic ball such as Si ₃ N ₄ (silicon nitride) is used. It became clear that the adhesion force was reduced, and as a result, the occurrence of fretting could be suppressed.

  Next, an experiment was conducted to confirm the effect of adopting a resin retainer with respect to the suppression of the mixing of metal wear powder into the grease. First, a bearing having a resin cage and an iron plate cage was prepared. And after operating these bearings on predetermined conditions, the amount of iron contained in grease was investigated. The test conditions were as follows. As the bearing, a double row tapered roller bearing (inner diameter: 120 mm, outer diameter: 220 mm, inner ring width: 155 mm, outer ring width: 160 mm) was used. The rotation speed was 2125 rpm. The radial load was 48.0 ± 9.8 kN. The test time was about 2120 hours.

  FIG. 11 is a diagram showing a comparison of the amount of iron contained in grease when a resin cage and an iron plate cage are used. As is apparent from FIG. 11, the amount of iron contained in the grease was significantly smaller when the resin cage was used than when the iron plate cage was used. From this, it became clear that the use of a bearing having a resin cage can suppress the mixing of metal into the grease.

  The embodiments and examples disclosed herein are illustrative in all respects and should not be construed as being restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The bearing for a main motor of the present invention can be applied particularly advantageously in a bearing for a main motor that requires an increase in manufacturing cost, suppression of occurrence of fretting, and extension of grease life.

  1 bogie, 2 bogie main body, 2a main motor mounting part, 2b underframe, 10 main motor, 11 frame, 12 stator, 12a coil, 13 rotor, 20 main shaft, 20a outer peripheral surface, 30 coupling, 40 driving device, 41 small gear, 42 large gear, 50 axle, 60 wheels, 70 axle bearing device, 80 first bearing device, 81 second bearing device, 82 first bearing, 83 housing, 84 front lid, 85 end lid, 86 second Bearing, 87 Displaceable member, 90 Main motor bearing, 91, 82a, 86a Outer ring, 92, 82b, 86b Inner ring, 93, 82c, 86c Rolling element, 94, 82d, 86d Cage, 91a Outer ring rolling surface, 92a Inner ring rolling surface.

Claims (6)

In a main motor of a railway vehicle, a main motor bearing that supports a main shaft so as to be rotatable about an axis with respect to a member arranged to face the outer peripheral surface of the main shaft,
An outer ring made of steel having an outer ring rolling surface on the inner circumferential surface;
An inner ring rolling surface on the outer peripheral surface, disposed on the inner side of the outer ring so that the inner ring rolling surface faces the outer ring rolling surface, and an inner ring made of steel;
A plurality of rolling elements arranged in contact with the outer ring rolling surface and the inner ring rolling surface and arranged side by side on an annular track;
A cage for holding the rolling elements at a predetermined pitch in the circumferential direction;
The rolling element is a ceramic ball,
The retainer is a bearing for a main motor made of resin.   The bearing for main motors according to claim 1 which is an open type bearing.   The bearing for a main motor according to claim 1, wherein the rolling element is made of silicon nitride.   The main motor bearing according to claim 1, wherein the cage is made of a polyamide resin.   The bearing for main motors of any one of Claims 1-4 which is a deep groove ball bearing.   The bearing for main motors of any one of Claims 1-5 which supports the free side of the said main axis | shaft.

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