Double-row rolling bearings

Abstract

To provide a double-row rolling bearing that can extend the lubrication life. [Solution] The double-row rolling bearing is used with grease lubrication, with both axial end faces sealed. Between the rows of the inner circumferential surface 4a of the outer ring, there is a stationary space increasing means 5 that increases the volume of stationary space in the entire space inside the bearing. The stationary space increasing means 5 is an annular recess provided on the inner circumferential surface 4a of the outer ring, capable of holding grease. The stationary space inside the bearing has stationary spaces A1 and A2, and stationary space B surrounded by the inner and outer rings and the cage assembly. The amount of grease sealed in the spatial volume of stationary spaces A1 and A2 satisfies the following condition: 5% × (spatial volume of stationary space A1 + stationary space A2)

Description

Technical Field

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[0003]

[0001] The present invention relates to a double-row rolling bearing applied to a sealed double-row tapered roller bearing or the like, and particularly to a bearing used for railway vehicle applications or the like.

Background Art

[0002] In the axle bearings of railway vehicles, in recent years, it has been required to extend the maintenance cycle. Although it is necessary to extend the lubrication life, in grease lubrication, if the enclosed amount is increased, there is a concern about the increase in the bearing temperature due to the entrainment of the grease. To solve these problems, it is important to increase the internal space volume of the bearing and the ratio of grease filling.

[0003] The applicant of the present application has proposed a bearing device shown in FIG. 7 (Patent Document 1) for the purpose of reducing maintenance man-hours and equipment costs. This bearing device has an intermediate grease supply mechanism 31 that supplies auxiliary grease 35 to the existing grease enclosed inside the bearing. The intermediate grease supply mechanism 31 fills a bag body with water, allows the water to leak out from the bag body due to the aging deterioration of the bag body, and increases the volume of the expandable body 34 by contact with the water. The increase in the volume of the expandable body 34 pushes the auxiliary grease 35 into the inside of the rolling bearing 17.

[0004] <00000​​​​​​​​​​​​​Japanese Patent Publication No. 2020-148321 [Patent Document 2] Japanese Utility Model Publication No. 6-45117 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Patent Document 1 suggests that the lubrication life of bearings can be extended by supplying auxiliary grease midway through the process, which is thought to lead to an extension of the vehicle's maintenance cycle. However, the timing of supplying auxiliary grease depends on the deterioration of the bag due to heat generated by the bearing, so the material and thickness of the bag must be carefully examined for each operating condition, making control complicated. There are concerns that the deteriorated grease inside the bearing will not be discharged to the outside of the bearing. There is a concern that the increased grease capacity inside the bearing will increase the chances of temperature rise due to grease entrapment, or that the agitation of the auxiliary grease immediately after it is added to the bearing may cause a temporary rise in bearing temperature.

[0007] In Patent Document 2, it is believed that by providing a recess at the end of the inner ring adjacent to the inner ring spacer, lubrication inside the bearing is contributed by the centrifugal force when the inner ring rotates, enabling maintenance-free operation for extended periods. However, this shape is only applicable to bearings installed side-by-side via an inner ring spacer, and there is a possibility that foreign matter may enter the grease-filled portion during bearing press-fitting.

[0008] The object of the present invention is to provide a double-row rolling bearing that can extend its lubrication life. [Means for solving the problem]

[0009] The double-row rolling bearing of the present invention is a double-row rolling bearing used with grease lubrication, An inner ring, an outer ring, a double row of rollers provided between the inner and outer rings, a retainer that holds these rollers, and sealing members provided on both axial end faces, Between the rows on the inner surface of the outer ring, there is a means for increasing the volume of the stationary space in the entire space inside the bearing, and the means for increasing the stationary space is an annular recess provided on the inner surface of the outer ring that is capable of holding the grease. The stationary space inside the bearing is A stationary space A1 is a space that the rollers and the cage do not pass through when the bearing rotates, surrounded by the inner and outer rings, the sealing member on one end of the bearing, the oil drain or slinger, and the cage assembly including the rollers and the cage. A stationary space A2 is a space that the rollers and the cage do not pass through when the bearing rotates, surrounded by the inner and outer rings, the sealing member on the other end of the bearing, the rear cover or slinger, and the cage assembly including the rollers and the cage. The bearing has an inner and outer ring, and a cage assembly including two rows of rollers and the cage, which has a stationary space B through which the rollers and the cage do not pass when the bearing rotates. The amount of grease sealed in the spatial volume of the aforementioned stationary space A1 and stationary space A2 satisfies the following conditions. 5% × (Spatial volume of stationary space A1 + stationary space A2) < Amount of grease sealed in the spatial volume of stationary space A1 + stationary space A2 ≤ 25% × (Spatial volume of stationary space A1 + stationary space A2) The aforementioned "static space" refers to the space within the entire bearing where, during bearing rotation, rotating elements such as rolling elements and cages do not pass through.

[0010] This configuration includes a static space increasing means between the rows on the inner surface of the outer ring, which increases the volume of the static space within the entire space inside the bearing. The static space increasing means is an annular recess provided on the inner surface of the outer ring, capable of holding the grease. As a result, the amount of grease remaining in the static space is increased compared to conventional structures without the static space increasing means, and the amount of grease sealed inside the bearing can be increased while suppressing the temperature rise caused by grease entrapment. Furthermore, it is possible to retain more base oil in the grease in the moving space and the static space during operation, thereby suppressing the acceleration of oil degradation. Therefore, the lubrication life can be extended without changing the internal design of existing rolling bearings.

[0011] In particular, by defining the amount of grease to be sealed in the spatial volume of the stationary spaces A1 and A2 as described above, the grease that is ejected from the moving space is accommodated in the stationary spaces A1 and A2 with ample room, which has the effect of suppressing the temperature rise of the bearing caused by grease entrapment. Furthermore, the oil separation rate of the grease in the moving space and stationary space B can be kept lower. As a result, it is possible to retain more base oil in the grease, suppress the acceleration of oil degradation, and extend the lubrication life. Since the means for increasing the stationary space is an annular recess provided on the inner circumferential surface of the outer ring that is capable of holding grease, the recess can be provided on the inner circumferential surface of the outer ring relatively easily by machining or the like.

[0012] Furthermore, the double-row rolling bearing of the present invention is a double-row rolling bearing used with grease lubrication, An inner ring, an outer ring, a double row of rollers provided between the inner and outer rings, a retainer that holds these rollers, and sealing members provided on both axial end faces, Between the rows on the inner surface of the outer ring, there is a means for increasing the volume of the stationary space in the entire space inside the bearing, and the means for increasing the stationary space is an annular recess provided on the inner surface of the outer ring that is capable of holding the grease. As the internal space of the bearing, dynamic spaces A3 and A4 are provided, which are the space through which the cage assembly, including the two rows of rollers and the cage, passes during rotation, excluding the volume of the cage assembly when it is at rest. The amount of grease sealed in the spatial volume of the aforementioned dynamic space A3 and the aforementioned dynamic space A4 satisfies the following conditions. 10% × (Spatial volume of dynamic space A3 + dynamic space A4) < Amount of grease filled in the spatial volume of dynamic space A3 + dynamic space A4 ≤ 45% × (Spatial volume of dynamic space A3 + dynamic space A4)

[0013] This configuration includes a means for increasing the static space between the rows on the inner surface of the outer ring, and this means for increasing the static space is an annular recess on the inner surface of the outer ring that is capable of holding grease. As a result, the amount of grease remaining in the static space is increased compared to conventional structures that do not have a means for increasing the static space, and it is possible to increase the amount of grease sealed inside the bearing while suppressing the temperature rise caused by grease entrapment.

[0014] Furthermore, by defining the amount of grease to be sealed in the spatial volumes of the moving spaces A3 and A4 as described above, it is possible to suppress the temperature rise of the bearing caused by grease entrapment by ejecting some of the grease from the moving spaces A3 and A4. In addition, the oil separation rate of the grease in the moving spaces A3 and A4 and the stationary space can be kept lower. As a result, it is possible to retain more base oil in the grease, suppress the acceleration of oil degradation, and extend the lubrication life.

[0015] The spatial volume of the stationary space B may have the following relationship with respect to the total spatial volume inside the bearing. 15% × Total spatial volume ≤ Spatial volume of stationary space B By satisfying the above relationship, it becomes possible to ensure a sufficient amount of base oil remaining in the grease in the moving space and the stationary space B, thereby suppressing the acceleration of oil degradation.

[0016] The spatial volume of space a in the recess may have the following relationship with respect to the spatial volume of the stationary space B excluding space a. 0% × spatial volume of stationary space B excluding space a ≤ spatial volume of space a ≤ 100% × spatial volume of stationary space B excluding space a By satisfying the above relationship, it becomes possible to ensure a sufficient amount of base oil remaining in the grease in the moving space and the stationary space B, thereby suppressing the acceleration of oil degradation.

[0017] The spatial volumes of the dynamic space A3 and the dynamic space A4 may have the following relationship with respect to the total spatial volume inside the bearing. 15% × total space volume ≤ space volume of dynamic space A3 + A4 ≤ 45% × total space volume When the above relationship is satisfied, sufficient capacity of the static space is ensured for the amount of grease ejected from the dynamic spaces A3 and A4. Therefore, heat generation of the bearing is suppressed, and the lubrication life can be further extended.

[0018] The grease existing in the dynamic spaces A3 and A4 accumulates in the static space due to the scraping by the roller and the influence of centrifugal force. When the ratio of the dynamic spaces A3 + A4 to the total space volume is less than 15%, the amount of grease ejected from the dynamic spaces A3 and A4 is small, and the influence of heat generation due to re-winding of the grease is small. However, since the ratio occupied by the tapered roller in the total space volume of the bearing becomes small and the rated load with respect to the bearing dimensions becomes too low, it is not recommended. When the ratio of the dynamic spaces A3 + A4 to the total space volume is greater than 45%, the capacity of the static space has to be reduced for the amount of grease ejected from the dynamic spaces A3 and A4. When the dynamic space increases and the static space decreases, re-winding of the grease frequently occurs due to the grease returning again to the dynamic spaces A3 and A4 during use. When the initial grease filling amount is restricted to suppress heat generation, the lubrication life decreases due to insufficient amount of grease.

[0019] The space volumes of the static space A1 and the static space A2 may have the following relationship with respect to the total space volume inside the bearing. 30% × total space volume ≤ static space A1 + A2 ≤ 60% × total space volume When the above relationship is satisfied, a space for accumulating the grease ejected by centrifugal force or the like is ensured. Therefore, heat generation of the bearing can be suppressed, and the lubrication life can be further extended.

[0020] During use, due to the influence of centrifugal force and the influence of the roller scraping the grease, the grease accumulates in the static spaces A1 and A2. When the ratio of the static spaces A1 + A2 to the total space volume is less than 30%, the space for accumulating the grease is small, and the ejected grease returns to the range of the dynamic space, and heat generation due to grease re-winding frequently occurs. When the filling amount of the grease is restricted to suppress heat generation, the lubrication life decreases due to insufficient amount of grease. If the ratio of the stationary space A1+A2 to the total spatial volume is greater than 60%, sufficient space can be secured for grease ejected by centrifugal force, etc., and heat generation in the bearing can be suppressed. However, in this case, the proportion of the rollers to the total spatial volume of the bearing becomes small, and the rated load relative to the bearing dimensions becomes too low, so this is not recommended.

[0021] The amount of grease to be filled into the spatial volume of the aforementioned stationary space B may satisfy the following conditions. 20% × volume of stationary space B ≤ amount of grease filled in the volume of stationary space B In this case, the amount of base oil remaining in the grease in stationary space B can be secured sufficiently and more reliably.

[0022] The double-row rolling bearing may also be a bearing that rotatably supports the axle of a railway vehicle. In this case, the lubrication life of the double-row rolling bearing, which is the axle bearing of the railway vehicle, can be extended, making it possible to extend the maintenance cycle compared to existing railway vehicles. [Effects of the Invention]

[0023] The present invention provides a double-row rolling bearing for use with grease lubrication, comprising an inner ring, an outer ring, a double row of rollers provided between the inner and outer rings, a cage for holding these rollers, seal members provided on both axial end faces, and a means for increasing the volume of the stationary space in the entire space inside the bearing, between the rows on the inner circumferential surface of the outer ring, wherein the means for increasing the volume of the stationary space is an annular recess provided on the inner circumferential surface of the outer ring that is capable of holding the grease, and the stationary space inside the bearing comprises the inner and outer rings, the seal member on one end of the bearing, an oil drainer or slinger, and a cage assembly including the rollers and the cage. The bearing has a stationary space A1 surrounded by the upright parts, which is a space through which the rollers and the cage do not pass when the bearing rotates; a stationary space A2 surrounded by the inner and outer rings, the sealing member on the other end of the bearing, the rear cover or slinger, and the cage assembly including the rollers and the cage, which is a space through which the rollers and the cage do not pass when the bearing rotates; and a stationary space B surrounded by the inner and outer rings, the cage assembly including two rows of rollers and the cage, which is a space through which the rollers and the cage do not pass when the bearing rotates. The amount of grease sealed in the spatial volume of stationary spaces A1 and A2 satisfies the following conditions. 5% × (Spatial volume of stationary space A1 + stationary space A2) < Amount of grease sealed in the spatial volume of stationary space A1 + stationary space A2 ≤ 25% × (Spatial volume of stationary space A1 + stationary space A2) Therefore, the lubrication life of double-row rolling bearings can be extended. [Brief explanation of the drawing]

[0024] [Figure 1] This is a longitudinal cross-sectional view of a double-row rolling bearing according to a first embodiment of the present invention. [Figure 2] This is a magnified view of the area around part II in Figure 1. [Figure 3] This figure shows the oil separation rate of the grease inside the bearing. [Figure 4] This figure shows the oil separation rate of the grease inside the bearing. [Figure 5] This is a longitudinal cross-sectional view of a double-row rolling bearing according to a second embodiment of the present invention. [Figure 6]This is a longitudinal cross-sectional view of a double-row rolling bearing according to a third embodiment of the present invention. [Figure 7] This is an enlarged cross-sectional view of a conventional intermediate lubrication mechanism. [Figure 8] This is a longitudinal cross-sectional view of another conventional example of a double-row tapered roller bearing. [Modes for carrying out the invention]

[0025] [First Embodiment] A double-row rolling bearing according to an embodiment of the present invention will be described with reference to Figures 1 to 4. The double-row rolling bearing is applied, for example, to a bearing unit that rotatably supports the axle of a railway vehicle. The double-row rolling bearing shown in Figure 1 is a double-row tapered roller bearing 1. In this specification, the double-row tapered roller bearing 1 may be simply referred to as bearing 1. The bearing unit BU comprises a double-row tapered roller bearing 1 and accessory parts 2 provided on both axial sides of the bearing 1.

[0026] <Schematic configuration of a double-row tapered roller bearing> The double-row tapered roller bearing 1 is used with grease lubrication, with both axial end faces sealed. Grease is sealed in the entire space inside the bearing between the inner and outer rings 3 and 4. A stationary space increasing means 5, described later, is provided between the rows on the inner circumferential surface 4a of the outer ring (Figure 2). The bearing is a so-called outward-facing double-row tapered roller bearing 1 and is capable of receiving radial loads and axial loads in both directions. The outward-facing double-row tapered roller bearing 1 has a longer distance between points of application and can receive larger moment loads than an inward-facing double-row tapered roller bearing of the same bearing size.

[0027] The double-row tapered roller bearing 1 comprises a split inner ring 3, 3, an integrated outer ring 4, a double row of tapered rollers 6 provided between the raceway surfaces 3a, 4b of the inner and outer rings 3, 4, a cage 7 that holds these tapered rollers 6, and seal members 8, 8 provided on the end faces on both sides in the axial direction. A pair of cages 7 are provided for each row of rollers. The two cages 7, 7 are spaced apart from each other in the axial direction. The inner and outer rings 3, 4 are made of bearing steel or carburized steel. In this embodiment, the outer ring is an integrated type, but it may also be a split type outer ring.

[0028] <Included parts, etc.> Attachment 2 includes, for example, an oil drainer 9 and a rear cover 10. The rear cover 10 is attached to the bearing 1 on the axial wheel side (right side in Figure 1) of the axle 11. A sleeve (not shown) or the like is fixed to the outer circumferential surface of the rear cover 10, and a seal outer ring 12 is fixed to the inner circumferential surface of the outer ring which connects to the outer ring end face. A seal 13 and a seal ring (not shown) are provided between the sleeve and the seal outer ring 12. The seal ring may be absent. The seal 13 is attached to the seal outer ring 12 and together with the seal outer ring 12 and the seal ring constitute a seal member 8. The seal 13 slides against the sleeve, and the seal ring is attached to the seal outer ring 12 to form a labyrinth seal between itself and the sleeve. If there is no seal ring, the seal 13 slides directly against the rear cover 10 and constitutes a seal.

[0029] The oil drain 9 is attached to the axle end of the axle 11. Similar to the rear cover 10, a sleeve or the like (not shown) is fixed to the outer circumferential surface of the oil drain 9, and a seal outer ring 12 is fixed to the inner circumferential surface of the outer ring. A seal 13 and a seal ring (not shown) are provided between the sleeve and the seal outer ring 12. The seal 13 is attached to the seal outer ring 12 and together with the seal outer ring 12 and the seal ring constitute a seal member 8. The seal 13 slides against the sleeve, and the seal ring is attached to the seal outer ring 12, forming a labyrinth seal between it and the sleeve. The oil drain 9, like the rear cover, may not have a seal ring.

[0030] <Regarding the entire space inside the bearing> The entire annular space inside the bearing is provided between the outer circumferential surface 3b of the inner ring and the inner circumferential surface 4a of the outer ring. The entire space inside the bearing has a stationary space A1, a stationary space A2, a stationary space B, and dynamic spaces A3 and A4. The entire space inside the bearing is also simply called the "bearing space". The total volume of the space inside the bearing is the volume of stationary spaces A1, A2 + stationary space B + dynamic spaces A3 and A4. Stationary space A1 is an annular space surrounded by the inner and outer rings 3 and 4, the seal member 8 on one end of the bearing, the oil drain 9, and the cage assembly including the tapered rollers 6 and the cage 7, and is a space through which the tapered rollers 6 and the cage 7 do not pass when the bearing rotates.

[0031] The stationary space A2 is an annular space surrounded by the inner and outer rings 3 and 4, the sealing member 8 on the other end of the bearing, the rear cover 10, and the cage assembly including the tapered rollers 6 and the cage 7, and is a space through which the tapered rollers 6 and the cage 7 do not pass when the bearing rotates. The stationary space B is the space enclosed by the inner and outer rings 3 and 4, and the cage assembly which includes two rows of tapered rollers 6, 6 and cages 7, 7, and is the space through which the tapered rollers 6 and cages 7 do not pass when the bearing rotates. Dynamic spaces A3 and A4 are the dynamic spaces obtained by subtracting the volume of the cage assembly when it is at rest from the space through which the cage assembly, which includes two rows of tapered rollers 6,6 and cages 7,7, passes during rotation. Dynamic space A3 is the space of one row adjacent to the stationary space A1, and dynamic space A4 is the space of the other row adjacent to the stationary space A2.

[0032] <Means for increasing static space> The stationary space increasing means 5 increases the volume of stationary space in the entire space inside the bearing. Specifically, as shown in Figure 2, the stationary space increasing means 5 is an annular recess provided on the inner circumferential surface 4a of the outer ring, capable of holding grease. The recess 5, which has a rectangular cross-section, is provided in the axial center of the inner circumferential surface 4a of the outer ring, which is included in the stationary space B. By providing space a of the recess 5 for the purpose of replenishing grease in the axial center of the inner circumferential surface 4a of the outer ring, it is possible to increase the amount of grease sealed in the entire space inside the bearing without changing the main dimensions, component configuration, and specifications of the bearing, and thus extend the lubrication life. The main dimensions are the inner diameter, outer diameter, and width dimensions of the bearing 1 shown in Figure 1. The specifications are the rated load of the bearing 1, the load direction it can withstand, etc.

[0033] <Parameters> The space enclosed by the outer circumferential surface 3b of the inner ring, the inner circumferential surface 4a of the outer ring, and the sealing members 8, 8 of the bearing 1, excluding the volume of the cages 7, 7 and the tapered rollers 6, is designed to satisfy the following conditions. (1) 15% × total spatial volume ≤ spatial volume of stationary space B (2) 0% × spatial volume of stationary space B excluding space a ≤ spatial volume of space a ≤ 100% × spatial volume of stationary space B excluding space a (3) 20% × volume of stationary space B ≤ amount of grease filled in the volume of stationary space B (4) 15% × total space volume ≤ space volume of dynamic space A3 + A4 ≤ 45% × total space volume (5)30%×total space volume≦Stationary space A1+A2≦60%×total space volume [Examples]

[0034] The effect obtained by satisfying the aforementioned formula was evaluated as follows. [Table 1]

[0035] [Table 2]

[0036] <Durability Test (1)> A durability test was conducted on bearing 1. The test conditions are shown in Table 3. The test bearing and the initial grease filling amount (initial grease application amount) are shown in Table 4. In Table 3, "Dmn" is the value obtained by multiplying the pitch circle diameter Dm (unit: mm) of bearing 1 by the rotational speed n (unit: rpm) of inner ring 3. The pitch circle diameter Dm is calculated by (inner ring inner diameter + outer ring outer diameter) / 2. "Cr" is the basic dynamic load rating, and "equivalent to EN12082 conditions" refers to the conditions under which bearing 1 with the following main dimensions is operated continuously for a specified period (e.g., 7 to 8 months). Inner ring inner diameter φ130mm × Outer ring outer diameter φ240mm × Width 160mm

[0037] [Table 3] [Table 4]

[0038] Figure 3 shows the oil separation rate inside the bearing after the aforementioned durability test. The "oil separation rate" is calculated using the following formula. Oil separation rate (%) = {(Mass of oil in new grease - Mass of oil in used grease) / Mass of oil in new grease} × 100 In Example Y, where the ratio of the spatial volume of space "a" to the spatial volume of static space B is 10% or more and less than 100%, the oil separation rate is lower and the base oil residue rate is higher in each part of the dynamic spaces A3 and A4 and static space a compared to Example X.

[0039] [Table 5]

[0040] [Table 6]

[0041] <Durability Test (2)> A durability test was conducted on bearing 1. The test conditions were the same as those shown in Table 3 above. The test bearing and the initial grease filling amount (initial grease application amount) are shown in Table 7. [Table 7] Bearing temperature data was obtained during the durability test. The bearing temperature was measured, for example, at the temperature of the outer ring, which is a fixed ring. The average temperature of Example Y is set to "1", and the average temperature ratio of Example Z to Example Y is shown in Table 8. The oil separation rate of the grease inside the bearing is shown in Figure 4. This oil separation rate is the same as the definition explained above along with Figure 3. Example Z, in which the initial grease application amount was changed as shown in equations (5) and (4), has an effect of suppressing the temperature rise of the bearing, and as shown in Figure 4, the oil separation rate of Example Z is lower than that of Example Y in each part of the stationary section A1+A2, stationary space B, and dynamic space A3+A4.

[0042] [Table 8]

[0043] <Effects and Effects> The double-row rolling bearing 1 described above is equipped with a static space increasing means 5 between the rows on the inner circumferential surface 4a of the outer ring, which increases the volume of the static space B in the entire space inside the bearing. As a result, the amount of grease remaining in the static space is increased compared to conventional structures that do not have a static space increasing means, and the amount of grease sealed inside the bearing can be increased while suppressing the temperature rise due to grease entrapment. In addition, it is possible to retain more base oil in the grease of the moving spaces A3, A4 and the static space B during operation, thereby suppressing the acceleration of oil degradation. Therefore, the lubrication life can be extended without changing the internal design of existing rolling bearings.

[0044] The means for increasing the stationary space is an annular recess 5 provided on the inner circumferential surface 4a of the outer ring, which is capable of holding grease. Therefore, the recess 5 can be provided on the inner circumferential surface 4a of the outer ring relatively easily by machining or the like. The recess 5 is provided in the axial center of the inner circumferential surface 4a of the outer ring, which is contained within the stationary space B surrounded by the inner and outer rings 3, 4 and the cage assembly including two rows of tapered rollers 6, 6 and cages 7, 7. This makes it possible to increase the spatial volume of the stationary space B. Consequently, it is possible to increase the spatial volume inside the bearing without changing the internal design, including the main dimensions, component configuration, and specifications of the existing double-row tapered roller bearing. Along with this, the ratio of the stationary space to the total space inside the bearing increases, making it possible to increase the amount of grease that is not involved in rotation. This increases the amount of base oil remaining in the grease that remains in the dynamic space A3 + dynamic space A4 + stationary space B that affects rotation, suppressing accelerated deterioration of the oil and thus extending the lubrication life.

[0045] To achieve the above effects to the fullest extent, it is desirable to satisfy all of the following equations (1), (2), and (3). (1) 15% × total spatial volume ≤ spatial volume of stationary space B (2) 0% × spatial volume of stationary space B excluding space a ≤ spatial volume of space a ≤ 100% × spatial volume of stationary space B excluding space a (3) 20% × volume of stationary space B ≤ amount of grease filled in the volume of stationary space B

[0046] (4) 15% × total space volume ≤ space volume of dynamic space A3 + A4 ≤ 45% × total space volume The grease present in the dynamic spaces A3 and A4 accumulates in the stationary spaces A1 and A2 due to the effects of being pushed aside by the tapered rollers 6 and centrifugal force. If the ratio of dynamic spaces A3+A4 to the total space volume is less than 15%, the amount of grease ejected from dynamic spaces A3 and A4 is small, and the effect of heat generation due to grease re-entry is small. However, this is not recommended because the proportion of tapered rollers 6 that occupy to the total space volume of the bearing becomes small, and the rated load relative to the bearing dimensions becomes too low.

[0047] When the ratio of the dynamic space A3+A4 to the total space volume is 15% or more and less than 30%, sufficient capacity of the static space A1 and A2 is ensured to compensate for the amount of grease ejected from the dynamic space A3 and A4. In this case, heat generation in bearing 1 is suppressed, resulting in an extended lubrication life. When the ratio of the dynamic space A3+A4 to the total space volume is between 30% and 45%, a certain amount of capacity in the static space A1 and A2 is secured to compensate for the amount of grease ejected from the dynamic space A3 and A4. As a result, the heat generation of bearing 1 is suppressed to some extent, and a slight extension of lubrication life can be obtained.

[0048] If the ratio of the dynamic space A3+A4 to the total space volume is greater than 45%, the capacity of the static space A1 and A2 is insufficient to accommodate the amount of grease ejected from the dynamic space A3 and A4, resulting in frequent grease re-entry as grease returns to the dynamic space during use. If the initial amount of grease sealed is limited to suppress heat generation, a reduction in lubrication life will occur due to insufficient grease.

[0049] (5)30%×total space volume≦Stationary space A1+A2≦60%×total space volume During use, grease accumulates in the stationary spaces A1 and A2 due to the effects of centrifugal force and the tapered rollers 6 dispersing the grease. If the ratio of stationary spaces A1+A2 to the total space volume is less than 30%, there is insufficient space for grease to accumulate, and the grease that is thrown back into the dynamic spaces A3 and A4 frequently generates heat due to grease entrapment. If the amount of grease sealed in is limited to suppress heat generation, the lubrication life will be reduced due to insufficient grease.

[0050] When the ratio of the stationary space A1+A2 to the total volume is between 30% and 40%, a certain amount of space is secured for the grease that is ejected by centrifugal force, etc., to remain. As a result, the heat generation of bearing 1 is suppressed to some extent, and a slight extension of the lubrication life can be obtained. When the ratio of the stationary space A1+A2 to the total volume is between 40% and 60%, sufficient space can be secured for the grease that has been ejected by centrifugal force, etc., to remain. This suppresses heat generation in bearing 1, thereby extending the lubrication life.

[0051] If the ratio of the stationary space A1+A2 to the total spatial volume is greater than 60%, sufficient space can be secured for the grease that has been ejected by centrifugal force, etc., and heat generation of bearing 1 can be suppressed. However, in this case, the proportion that the tapered rollers 6 occupy to the total spatial volume of the bearing becomes small, and the rated load relative to the bearing dimensions becomes too low, so this is not recommended.

[0052] (5) The following conditions may also be met in addition to satisfying equation (5). 5% × (Spatial volume of stationary space A1 + stationary space A2) < Amount of grease sealed in the spatial volume of stationary space A1 + stationary space A2 ≤ 25% × (Spatial volume of stationary space A1 + stationary space A2) By defining the amount of grease to be sealed in the spatial volume of the stationary spaces A1 and A2 in this way, the grease that is ejected from the dynamic spaces A3 and A4 can be accommodated in the stationary spaces A1 and A2 with ample room, thereby suppressing the temperature rise of the bearing caused by grease entrapment. Furthermore, the oil separation rate of the grease in the dynamic spaces A3 and A4 and the stationary space B can be kept lower. This allows more base oil to remain in the grease, suppressing the acceleration of oil degradation and extending the lubrication life.

[0053] (4) The following conditions may also be met in addition to satisfying equation (4). 10% × (Spatial volume of dynamic space A3 + dynamic space A4) < Amount of grease filled in the spatial volume of dynamic space A3 + dynamic space A4 ≤ 45% × (Spatial volume of dynamic space A3 + dynamic space A4) By defining the amount of grease to be sealed in the spatial volumes of the moving spaces A3 and A4 in this way, it is possible to suppress the temperature rise of the bearing caused by grease entrapment by ejecting some of the grease from the moving spaces A3 and A4. Furthermore, the oil separation rate of the grease in the moving spaces A3 and A4 and the stationary space B can be kept lower. As a result, it is possible to retain more base oil in the grease, suppress the acceleration of oil degradation, and extend the lubrication life.

[0054] <Regarding other embodiments> In the following description, parts corresponding to matters previously described in each embodiment will be denoted by the same reference numerals, and redundant explanations will be omitted. When only a part of the configuration is described, the other parts of the configuration will be the same as those in the previously described embodiment unless otherwise specified. Identical configurations will produce the same effects. Not only are combinations of the parts specifically described in each embodiment possible, but partial combinations of embodiments are also possible, provided that there are no particular problems with the combination.

[0055] [Second embodiment: with inner wheel spacer, Figure 3] As shown in Figure 3, an inner ring spacer 14 may be provided between the two rows of split inner rings 3, 3. In the case of this bearing 1A, the distance between the points of action can be increased compared to a double-row tapered roller bearing without an inner ring spacer, thereby increasing the overall rigidity of the bearing, and the volume of the stationary space B can be increased according to the width dimension of the inner ring spacer. In addition, it provides the same effects as the embodiment described above.

[0056] Instead of the oil drain 9, a slinger fixed to the outer surface of the shaft 11 or the like may be used. Instead of the rear cover 10, a slinger fixed to the outer surface of the shaft 11 or the like may be used. The recesses 5 can also be provided at equal intervals around the circumference or at predetermined intervals in the circumferential direction. Alternatively, one recess 5 may be provided on the inner circumferential surface 4a of the outer ring. As a double-row rolling bearing, a four-row tapered roller bearing may be used. As a double-row rolling bearing, an inward-facing double-row tapered roller bearing may be used. The bearing body, with the accessory parts 2 and sealing member 8 removed from the bearing unit BU, can be traded independently in the market.

[0057] [Third embodiment: Double-row cylindrical roller bearing] As a double-row rolling bearing, a double-row cylindrical roller bearing 1B may be used, as shown in Figure 6. In this case, cylindrical rollers 6A are used for each of the double-row rollers. The double-row cylindrical roller bearing 1B is also equipped with a stationary space increasing means 5 that increases the volume of the stationary space B. Therefore, compared to a conventional structure without a stationary space increasing means, the amount of grease remaining in the stationary space increases, and the amount of grease sealed inside the bearing can be increased while suppressing the temperature rise due to grease entrapment. The outer circumferential surface of the outer ring 4 is provided with a screw hole 4c to which a grease nipple (not shown) can be attached and detached. This screw hole 4c communicates with a recess 5, which is a stationary space increasing means, and grease can be filled into the recess 5 from the grease nipple. In addition, it provides the same effects as the first embodiment described above. Double-row rolling bearings can also be used in applications other than railway vehicles, such as industrial machinery.

[0058] While embodiments of the present invention have been described above, the embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of symbols]

[0059] 1,1A...Double-row tapered roller bearing (double-row rolling bearing), 1B...Double-row cylindrical roller bearing (double-row rolling bearing), 3...Inner ring, 4...Outer ring, 4a...Inner surface of outer ring, 5...Recess (means for increasing stationary space), 6...Tapered roller (roller), 6A...Cylindrical roller (roller), 7...Cage, 8...Sealing member, 9...Oil drain, 10...Rear cover, 11...Axle, 14...Inner ring spacer

Claims

1. A double-row rolling bearing used with grease lubrication, An inner ring, an outer ring, a double row of rollers provided between the inner and outer rings, a retainer that holds these rollers, and sealing members provided on both axial end faces, Between the rows on the inner surface of the outer ring, there is a means for increasing the volume of the stationary space in the entire space inside the bearing, and the means for increasing the stationary space is an annular recess provided on the inner surface of the outer ring that is capable of holding the grease. The stationary space inside the bearing is A stationary space A1 is a space that the rollers and the cage do not pass through when the bearing rotates, surrounded by the inner and outer rings, the sealing member on one end of the bearing, the oil drain or slinger, and the cage assembly including the rollers and the cage. A stationary space A2 is a space that the rollers and the cage do not pass through when the bearing rotates, surrounded by the inner and outer rings, the sealing member on the other end of the bearing, the rear cover or slinger, and the cage assembly including the rollers and the cage. The bearing has an inner and outer ring, and a cage assembly including two rows of rollers and the cage, which has a stationary space B through which the rollers and the cage do not pass when the bearing rotates. The amount of grease sealed in the spatial volume of the aforementioned stationary space A1 and the aforementioned stationary space A2 is a double-row rolling bearing that satisfies the following conditions. 5% × (Spatial volume of stationary space A1 + stationary space A2) < Amount of grease sealed in the spatial volume of stationary space A1 + stationary space A2 ≤ 25% × (Spatial volume of stationary space A1 + stationary space A2)

2. A double-row rolling bearing used with grease lubrication, An inner ring, an outer ring, a double row of rollers provided between the inner and outer rings, a retainer that holds these rollers, and sealing members provided on both axial end faces, Between the rows on the inner surface of the outer ring, there is a means for increasing the volume of the stationary space in the entire space inside the bearing, and the means for increasing the stationary space is an annular recess provided on the inner surface of the outer ring that is capable of holding the grease. As the internal space of the bearing, dynamic spaces A3 and A4 are provided, which are the spaces through which the cage assembly, including the two rows of rollers and the cage, passes during rotation, excluding the volume of the cage assembly when it is at rest. The amount of grease sealed in the spatial volume of the aforementioned dynamic space A3 and the aforementioned dynamic space A4 is a double-row rolling bearing that satisfies the following conditions. 10% × (Spatial volume of dynamic space A3 + dynamic space A4) < Amount of grease sealed in the spatial volume of dynamic space A3 + dynamic space A4 ≤ 45% × (Spatial volume of dynamic space A3 + dynamic space A4)

3. A double-row rolling bearing according to claim 1, wherein the spatial volume of the stationary space B has the following relationship with respect to the total spatial volume inside the bearing: 15% × Total spatial volume ≤ Spatial volume of stationary space B

4. A double-row rolling bearing according to claim 1 or claim 3, wherein the spatial volume of space a in the recess has the following relationship with respect to the spatial volume of the stationary space B excluding space a: 0% × the volume of the stationary space B excluding space a ≤ the volume of space a ≤ 100% × the volume of the stationary space B excluding space a

5. A double-row rolling bearing according to claim 2, wherein the spatial volumes of the dynamic space A3 and the dynamic space A4 have the following relationship with respect to the total spatial volume inside the bearing: 15% × total space volume ≤ space volume of dynamic space A3 + A4 ≤ 45% × total space volume

6. A double-row rolling bearing according to claim 1 or claim 3, wherein the spatial volumes of the stationary space A1 and the stationary space A2 have the following relationship with respect to the total spatial volume inside the bearing: 30% x total space volume ≦ still space A1 + A2 ≦ 60% x total space volume

7. In the double-row rolling bearing described in claim 4, the amount of grease sealed in the spatial volume of the stationary space B is such that the following conditions are met for the double-row rolling bearing. 20% × volume of stationary space B ≤ amount of grease filled in the volume of stationary space B

8. A double-row rolling bearing according to claim 1 or claim 2, wherein the double-row rolling bearing is a bearing that rotatably supports the axle of a railway vehicle.

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