Double row rolling bearing

Abstract

To provide a double row rolling bearing which enables extension of the lubrication life.SOLUTION: A double row rolling bearing 1 is used lubricated by grease with both axial end surfaces sealed. Stationary space increasing means 5 for increasing the volumetric capacity of a stationary space in an entire space within the bearing is provided between rows on an outer ring inner peripheral surface 4a. The stationary space increasing means 5 is an annular recessed part which is provided on the outer ring inner peripheral surface 4a and may retain the grease. The double row rolling bearing 1 includes: inner rings 3, 3; an integral outer ring 4; and double row conical rollers 6, 6 provided between the inner rings 3 and the outer ring 4; retainers 7, 7 which retain these conical rollers 6, 6; and seal members 8, 8 provided on both axial end surfaces. The recessed part is provided at a center part in an axial direction of the outer ring inner peripheral surface 4a included in the stationary space B.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a double-row rolling bearing applied to sealed double-row tapered roller bearings and the like, and in particular to a bearing used for railway vehicles and the like. [Background technology]

[0002] In recent years, there has been a demand to extend the maintenance interval for axle bearings of railway vehicles. It is necessary to extend the lubrication life, but there is a concern that if the amount of grease filled is increased in the case of grease lubrication, the bearing temperature will rise due to grease entrapment. To solve this problem, it is important to increase the internal space volume of the bearing and to consider the proportion of grease filled.

[0003] The present applicant has proposed a bearing device shown in Fig. 7 with the aim of reducing maintenance man-hours and equipment costs (Patent Document 1). This bearing device has an intermediate lubrication mechanism 31 that supplies auxiliary grease 35 to the existing grease sealed inside the bearing. The intermediate lubrication mechanism 31 fills a bag with water, causes the water to seep out of the bag as the bag deteriorates over time, and increases the volume of the expansion body 34 by contacting with the water. The increase in volume of this expansion body 34 pushes the auxiliary grease 35 into the inside of the rolling bearing 17.

[0004] The present applicant has proposed a lubrication structure for a rolling bearing that allows for long-term operation without maintenance, as shown in Fig. 8 (Patent Document 2). Specifically, in a double-row rolling bearing, an inner ring spacer 50 is provided with an engagement portion that engages with the outer peripheries of the inner rings 51, 51 on both sides, and a lubricant reservoir recess 52 is provided on the inner diameter surface across the adjacent ends of the inner rings 51, 51 and the inner ring spacer 50. A lubricant outflow path such as a pore is provided that opens from the lubricant reservoir recess 52 to the space between the inner and outer rings 51, 53. Grease is sealed in the lubricant reservoir recess 52. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-148321 A [Patent Document 2] Japanese Utility Model Application Publication No. 6-45117 Summary of the Invention [Problem to be solved by the invention]

[0006] In Patent Document 1, the supplementary grease is supplied midway, which makes it possible to extend the lubrication life of the bearing and is thought to lead to an extension of the vehicle maintenance cycle. However, the timing of supplementary grease supply depends on the deterioration of the bag body due to heat generation from the bearing, so the material and thickness of the bag body must be carefully examined for each use condition, making control complicated. Since the deteriorated grease inside the bearing is not discharged to the outside of the bearing, there are the following concerns. There is a concern that the increased volume of grease enclosed inside the bearing increases the chance of temperature rise due to grease entrapment, or that the stirring of the auxiliary grease immediately after it is replenished inside the bearing may cause a temporary temperature rise in the bearing.

[0007] In Patent Document 2, by providing a recess on the end of the inner ring adjacent to the inner ring spacer, the centrifugal force generated when the inner ring rotates contributes lubrication to the inside of the bearing, which is thought to enable long-term operation without maintenance. However, this shape is only applicable to bearings that are installed side by side with an inner ring spacer, and there is a possibility that foreign matter may get into the grease-filled portion when the bearing is pressed into place.

[0008] An object of the present invention is to provide a double-row rolling bearing capable of extending the 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, The bearing comprises an inner ring, a one-piece outer ring, double rows of rollers provided between the inner and outer rings, a retainer that holds these rollers, seal members provided on both end faces in the axial direction, and static space increasing means between the rows on the inner circumferential surface of the outer ring for increasing the volume of static space in the entire space inside the bearing, the static space increasing means being annular recesses provided on the inner circumferential surface of the outer ring that are capable of holding the grease. The "static space" refers to the entire space inside the bearing through which rotating bodies such as rolling elements and a cage do not pass when the bearing rotates.

[0010] According to this configuration, a static space increasing means is provided between the rows on the inner peripheral surface of the outer ring, which increases the volume of the static space in the entire space inside the bearing. The static space increasing means is an annular recess provided on the inner peripheral surface of the outer ring, capable of holding the grease. Therefore, the amount of grease remaining in the static space is increased compared to a conventional structure not provided with a static space increasing means, and the amount of grease sealed inside the bearing can be increased while suppressing the rise in temperature caused by grease entrapment. In addition, it is possible to leave more base oil in the grease in the dynamic space and static space during operation, and suppress the promotion of deterioration of the oil. Therefore, the lubrication life can be extended without changing the internal design of the existing rolling bearing. Since the stationary space increasing means is an annular recess provided in the inner circumferential surface of the outer ring and capable of retaining grease, the recess can be relatively easily formed in the inner circumferential surface of the outer ring by machining or the like.

[0011] The total space inside the bearing is a stationary space A1, which is surrounded by the inner and outer rings, the seal member at one end of the bearing, an oil thrower or slinger, and a cage assembly including the rollers and the cage, and which is a space through which the rollers and the cage do not pass when the bearing rotates; a stationary space A2, which is a space through which the rollers and the cage do not pass when the bearing rotates, and which is surrounded by the inner and outer rings, the seal member on the other end side of the bearing, a rear cover or a slinger, and a cage assembly including the rollers and the cage; a stationary space B, which is surrounded by the inner and outer rings and a cage assembly including two rows of rollers and the cage, and which is a space through which the rollers and the cage do not pass when the bearing rotates; and dynamic spaces A3, A4 defined by excluding a volume of the cage assembly at rest from a space through which the cage assembly including the two rows of rollers and the cage passes during rotation, The recess may be provided in an axial center portion of the inner circumferential surface of the outer ring included in the stationary space B.

[0012] In this way, it is possible to increase the spatial volume of the stationary space B surrounded by the inner and outer rings and the cage assembly including the two rows of rollers and the cage. Therefore, it is possible to increase the spatial volume inside the bearing and extend the lubrication life without changing the internal design, including the main dimensions, component configuration, and specifications, of existing double row roller bearings.

[0013] 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 space volume ≦ space volume of stationary space B By satisfying the above relationship, it is possible to ensure a sufficient amount of base oil remaining in the grease in the dynamic spaces A3, A4 and the static space B, and to suppress the promotion of deterioration of the oil.

[0014] The spatial volume of the space a of the recess may have the following relationship with the spatial volume of the stationary space B excluding the space a. 0%×space volume of stationary space B excluding a space ≦space volume of a space ≦100%×space volume of stationary space B excluding a space By satisfying the above relationship, it is possible to ensure a sufficient amount of base oil remaining in the grease in the dynamic spaces A3, A4 and the static space B, and to suppress the promotion of deterioration of the oil.

[0015] 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% x total space volume ≦ space volume of dynamic space A3 + A4 ≦ 45% x total space volume When the above relationship is satisfied, the static spaces A1 and A2 have a sufficient capacity to accommodate the amount of grease expelled from the dynamic spaces A3 and A4, which suppresses heat generation in the bearings and further extends the lubrication life.

[0016] Grease present in the moving spaces A3 and A4 accumulates in the stationary spaces A1 and A2 due to the effects of centrifugal force and being pushed aside by the tapered rollers. If the ratio of moving spaces A3 + A4 to the total spatial volume is less than 15%, the amount of grease expelled from moving spaces A3 and A4 is small, and the impact of heat generation due to grease re-entering is small. However, the ratio of the tapered rollers to the overall spatial volume of the bearing becomes small, and the rated load for the bearing dimensions becomes too low, so this is not recommended. If the ratio of the dynamic space A3+A4 to the total spatial volume is greater than 45%, the capacity of the static spaces A1 and A2 will be insufficient for the amount of grease expelled from the dynamic spaces A3 and A4, and the grease will return to the dynamic spaces A3 and A4 during use, causing frequent re-entrapment of the grease. If the amount of grease initially injected is limited to suppress heat generation, the lubrication life will be reduced due to insufficient grease amount.

[0017] The spatial volumes of the stationary space A1 and the stationary space A2 may 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 When the above relationship is satisfied, a space is secured in which grease scattered by centrifugal force etc. can accumulate, thereby making it possible to suppress heat generation in the bearing and further extend the lubrication life.

[0018] During use, grease accumulates in the stationary spaces A1 and A2 due to the effects of centrifugal force and the tapered rollers pushing aside the grease. If the ratio of stationary spaces A1 + A2 to the total space volume is less than 30%, there is little space for grease to accumulate, and the grease that is blown away returns to the range of moving spaces A3 and A4, causing frequent heat generation due to grease entrapment. If the amount of grease filled is limited to suppress heat generation, the lubrication life will be reduced due to insufficient grease amount. If the ratio of stationary space A1 + A2 to the total spatial volume is greater than 60%, there will be enough space to retain grease scattered by centrifugal force, etc., and heat generation in the bearing can be suppressed. However, in this case, the ratio of the rollers to the total spatial volume of the bearing will be small, and the rated load for the bearing dimensions will be too low, so this is not recommended.

[0019] The amount of grease filled in the spatial volume of the stationary space B may satisfy the following condition. 20% x spatial volume of stationary space B ≦ Amount of grease filled in the spatial volume of stationary space B In this case, the remaining amount of base oil contained in the grease in the stationary space B can be ensured sufficiently and more reliably.

[0020] The amount of grease filled in the spatial volume of the stationary space A1 and the stationary space A2 may satisfy the following condition. 5% x (space volume of stationary space A1 + stationary space A2) < amount of grease filled in the space volume of stationary space A1 + stationary space A2 ≦ 25% x (space volume of stationary space A1 + stationary space A2)

[0021] By specifying the amount of grease to be filled in the spatial volume of the stationary spaces A1 and A2 in this way, the grease expelled from the moving spaces A3 and A4 can be accommodated in the stationary spaces A1 and A2 with a sufficient margin, which has the effect of suppressing the temperature rise of the bearing caused by the entrainment of grease. It is also possible to further reduce the oil separation rate of the grease in the moving spaces A3 and A4 and the stationary space B. This allows a large amount of base oil to remain in the grease, making it possible to suppress the accelerated deterioration of the oil, and extending the lubrication life.

[0022] The amount of grease filled in the spatial volume of each of the motion spaces A3 and A4 may satisfy the following condition. 10% x (space volume of moving space A3 + moving space A4) < amount of grease filled in the space volume of moving space A3 + moving space A4 ≦ 45% x (space volume of moving space A3 + moving space A4)

[0023] By specifying the amount of grease filled in the spatial volume of the dynamic spaces A3 and A4 in this way, some of the grease is expelled from the dynamic spaces A3 and A4, which has the effect of suppressing the temperature rise of the bearing caused by grease entrapment. It also makes it possible to further reduce the oil separation rate of the grease in the dynamic spaces A3 and A4 and the stationary space B. This allows a large amount of base oil to remain in the grease, making it possible to suppress the acceleration of deterioration of the oil, and extending the lubrication life.

[0024] The inner ring may be a split inner ring, and an inner ring spacer may be provided between the two rows of these split inner rings. In this case, the distance between the load points is made larger than in a double row tapered roller bearing that does not have an inner ring spacer, increasing the rigidity of the entire bearing, and the spatial volume of the stationary space B can be increased according to the width dimension of the inner ring spacer. The inner ring spacer is considered to be the "inner ring" when defining the stationary space B.

[0025] The double row rolling bearing may be a bearing that rotatably supports an 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, so that the maintenance cycle can be extended more than that of existing railway vehicles. Effect of the Invention

[0026] The double row rolling bearing of the present invention is a double row rolling bearing used with grease lubrication, and includes an inner ring, an integral outer ring, double rows of rollers provided between the inner and outer rings, a cage for holding these rollers, and seal members provided on both end faces in the axial direction. It also includes a static space increasing means between the rows on the inner peripheral surface of the outer ring for increasing the volume of the static space in the entire space inside the bearing, and this static space increasing means is an annular recess provided on the inner peripheral surface of the outer ring that can hold grease. This makes it possible to extend the lubrication life. [Brief description of the drawings]

[0027] [Figure 1] 1 is a vertical sectional view of a double-row rolling bearing according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a partially enlarged view of the periphery of a portion II in FIG. [Diagram 3] FIG. 4 is a diagram showing the oil separation rate of grease inside a bearing. [Figure 4] FIG. 4 is a diagram showing the oil separation rate of grease inside a bearing. [Diagram 5] FIG. 4 is a vertical sectional view of a double-row rolling bearing according to a second embodiment of the present invention. [Figure 6] FIG. 11 is a vertical sectional view of a double-row rolling bearing according to a third embodiment of the present invention. [Figure 7] FIG. 13 is an enlarged cross-sectional view of a conventional mid-stage greasing mechanism. [Figure 8] FIG. 11 is a vertical sectional view of another conventional double row tapered roller bearing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] [First embodiment] A double-row rolling bearing according to an embodiment of the present invention will be described with reference to Figs. 1 to 4. The double-row rolling bearing is applied to a bearing unit that supports the rotation of axles of a railway vehicle, for example. The double-row rolling bearing shown in Fig. 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 the double-row tapered roller bearing 1 and accessory parts 2 provided on both axial sides of the bearing 1.

[0029] <Outline of double-row tapered roller bearing configuration> 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, 4. A stationary space increasing means 5, described later, is provided between the rows of the inner circumferential surface 4a of the outer ring (Fig. 2). The bearing is a so-called outward-facing type double-row tapered roller bearing 1, and is capable of receiving radial loads and axial loads in both directions. The outward-facing type double-row tapered roller bearing 1 has a longer distance between the load points and can receive larger moment loads than an inward-facing type double-row tapered roller bearing of the same bearing size.

[0030] The double-row tapered roller bearing 1 comprises split inner rings 3, 3, one-piece outer ring 4, double-row tapered rollers 6 provided between raceway surfaces 3a, 4b of the inner and outer rings 3, 4, a cage 7 for holding these tapered rollers 6, and seal members 8, 8 provided on both end faces in the axial direction. A pair of cages 7 is provided for each roller row. The two cages 7, 7 are arranged spaced apart from each other in the axial direction. The inner and outer rings 3, 4 are made of bearing steel or carburized steel.

[0031] <Accessories, etc.> The accessory parts 2 include, for example, an oil thrower 9 and a rear cover 10. The rear cover 10 is attached to the axial wheel side of the axle 11 relative to the bearing 1 (right side in FIG. 1). A sleeve (not shown) is fixed to the outer peripheral surface of the rear cover 10, and a seal outer ring 12 is fixed to the inner peripheral surface of the outer ring connected to the end face of the outer ring. A seal 13 and a seal ring (not shown) are provided between the sleeve and the seal outer ring 12. There may be no seal ring. The seal 13 is attached to the seal outer ring 12, and together with the seal outer ring 12 and the seal ring, they constitute the 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 the seal 13 and the sleeve. When there is no seal ring, the seal 13 slides directly against the rear cover 10 to form a seal.

[0032] The oil thrower 9 is attached to the shaft end side of the axle 11. A sleeve (not shown) is fixed to the outer peripheral surface of the oil thrower 9, similar to the back cover 10, and an outer seal ring 12 is fixed to the inner peripheral surface of the outer ring. A seal 13 and a seal ring (not shown) are provided between the sleeve and the outer seal ring 12. The seal 13 is attached to the outer seal ring 12, and together with the outer seal ring 12 and the seal ring, they form a seal member 8. The seal 13 is in sliding contact with the sleeve, and the seal ring is attached to the outer seal ring 12 to form a labyrinth seal between the seal 13 and the sleeve. Like the back cover, the oil thrower 9 may not have a seal ring.

[0033] <About the entire space inside the bearing> Between the inner ring outer peripheral surface 3b and the outer ring inner peripheral surface 4a, an annular total space inside the bearing is provided. The total space inside the bearing has stationary space A1, stationary space A2, stationary space B, and dynamic spaces A3 and A4. The total space inside the bearing is also simply referred to as the "bearing space." The total spatial volume inside the bearing is the volume of stationary spaces A1 and 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 side of the bearing, the oil thrower 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.

[0034] The stationary space A2 is an annular space surrounded by the inner and outer rings 3, 4, the seal member 8 on the other end side of the bearing, the rear cover 10, and the retainer assembly including the tapered rollers 6 and the retainer 7, and is a space through which the tapered rollers 6 and the retainer 7 do not pass when the bearing rotates. The stationary space B is a space surrounded by the inner and outer rings 3, 4 and a cage assembly including two rows of tapered rollers 6, 6 and cages 7, 7, through which the tapered rollers 6 and cage 7 do not pass when the bearing rotates. The dynamic spaces A3 and A4 are dynamic spaces obtained by excluding the volume of the cage assembly at rest from the space through which the cage assembly including the two rows of tapered rollers 6, 6 and the cages 7, 7 passes when rotating. The dynamic space A3 is the space of one row adjacent to the static space A1, and the dynamic space A4 is the space of the other row adjacent to the static space A2.

[0035] <Methods for increasing static space> The static space increasing means 5 increases the volume of the static space in the entire space inside the bearing. Specifically, as shown in FIG. 2, the static space increasing means 5 is an annular recess provided on the inner peripheral surface 4a of the outer ring, capable of holding grease. A recess 5 having a rectangular cross-section hole shape is provided in the axial center of the inner peripheral surface 4a of the outer ring, which is included in the static space B. By providing a space a of the recess 5 for the purpose of replenishing grease in the axial center of the inner peripheral surface 4a of the outer ring, it is possible to increase the amount of grease filled in the entire space inside the bearing without changing the main dimensions, component configuration, and specifications of the bearing, and it is possible to extend the lubrication life. The main dimensions are the inner diameter, outer diameter, and width dimensions of the bearing 1 shown in FIG. 1. The specifications are the rated load of the bearing 1, the load direction that it can bear, etc.

[0036] <parameters> The space surrounded by the inner ring outer peripheral surface 3b, the outer ring inner peripheral surface 4a and the seal members 8, 8 of the bearing 1, excluding the volumes of the cages 7, 7 and the tapered rollers 6, is designed to satisfy the following conditions. (1) 15% × total space volume ≦ space volume of static space B (2) The spatial volume of the stationary space B excluding 0% × a space ≦ the spatial volume of the a space ≦ the spatial volume of the stationary space B excluding 100% × a space (3) 20% × spatial volume of stationary space B ≦ amount of grease filled in the spatial volume of stationary space B (4) 15% × total spatial volume ≦ spatial volume of dynamic space A3 + A4 ≦ 45% × total spatial volume (5)30%×total space volume≦Stationary space A1+A2≦60%×total space volume EXAMPLES

[0037] The effects obtained by satisfying the above formula were evaluated as follows. [Table 1]

[0038] [Table 2]

[0039] <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 amount of grease filled (initial amount of grease applied) are shown in Table 4. "Dmn" in Table 3 is the value obtained by multiplying the pitch circle diameter Dm (unit: mm) of bearing 1 by the rotation 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 the conditions of EN12082" refers to the conditions under which bearing 1 having the following main dimensions is operated continuously for a specified period (for example, 7 to 8 months). Inner ring inner diameter φ130mm x outer ring outer diameter φ240mm x width 160mm

[0040] [Table 3] [Table 4]

[0041] The oil separation rate inside the bearing after the durability test is shown in Figure 3. The "oil separation rate" is calculated by the following formula. Oil separation rate (%) = {(mass of oil in new grease - mass of oil in used grease) / mass of oil in new grease} x 100 Example Y, in which the ratio of the spatial volume of space "a" to the spatial volume of static space B is 10% or more but less than 100%, has a lower oil separation rate and a higher residual rate of base oil than Example X in each of the dynamic spaces A3, A4 and the static space a.

[0042] [Table 5]

[0043] [Table 6]

[0044] <Durability test (2)> A durability test was conducted on bearing 1. The test conditions were the same as those shown in Table 3 above. Table 7 shows the test bearing and the initial amount of grease filled (initial amount of grease applied). [Table 7] The bearing temperature data of the durability test was obtained. The bearing temperature was measured, for example, by measuring the temperature of the outer ring, which is the fixed ring. The average temperature of Example Y was 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 with reference to Figure 3. Example Z, in which the amount of initial grease applied was changed as shown in formulas (5) and (4), has the effect of suppressing the temperature rise of the bearing, and as shown in Figure 4, the oil separation rate is lower than that of Example Y in each of the static section A1+A2, static space B, and dynamic space A3+A4.

[0045] [Table 8]

[0046] <Action and effect> According to the double row rolling bearing 1 described above, the space between the rows of the inner peripheral surface 4a of the outer ring is provided with a static space increasing means 5 that increases the volume of the static space B in the entire space inside the bearing. Therefore, the amount of grease remaining in the static space is increased compared to a conventional structure that does not have a 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. In addition, it is possible to leave more base oil in the grease in the moving spaces A3, A4 and static space B during operation, and suppress the acceleration of deterioration of the oil. Therefore, the lubrication life can be extended without changing the internal design of the existing rolling bearing.

[0047] The stationary space increasing means is an annular recess 5 that is provided on the inner peripheral surface 4a of the outer ring and is capable of retaining grease. For this reason, the recess 5 can be relatively easily provided on the inner peripheral surface 4a of the outer ring by machining or the like. The recess 5 is provided in the axial center of the inner peripheral surface 4a of the outer ring, which is included in the stationary space B surrounded by the inner and outer rings 3, 4 and the cage assembly including the two rows of tapered rollers 6, 6 and the cage 7, 7. This makes it possible to increase the spatial volume of the stationary space B. This makes it 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. As a result, 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 caught in the rotation, increasing the amount of base oil remaining in the grease remaining in the dynamic space A3 + dynamic space A4 + static space B that affects the rotation, and suppressing the promotion of deterioration of the oil, thereby enabling the extension of the lubrication life.

[0048] In order to obtain the above-mentioned effect to a large extent, it is desirable to satisfy all of the following expressions (1), (2), and (3). (1) 15% × total space volume ≦ space volume of static space B (2) The spatial volume of the stationary space B excluding 0% × a space ≦ the spatial volume of the a space ≦ the spatial volume of the stationary space B excluding 100% × a space (3) 20% × spatial volume of stationary space B ≦ amount of grease filled in the spatial volume of stationary space B

[0049] (4) 15% × total spatial volume ≦ spatial volume of dynamic space A3 + A4 ≦ 45% × total spatial volume Grease present in the moving spaces A3, A4 accumulates in the stationary spaces A1, A2 due to the effects of centrifugal force and being pushed aside by the tapered rollers 6. If the ratio of moving spaces A3 + A4 to the total spatial volume is less than 15%, the amount of grease expelled from moving spaces A3, A4 is small and the impact of heat generation due to grease re-entering is small. However, the ratio of the tapered rollers 6 to the spatial volume of the entire bearing becomes small, and the rated load for the bearing dimensions becomes too low, so this is not recommended.

[0050] When the ratio of the dynamic space A3+A4 to the total spatial volume is 15% or more and less than 30%, the static spaces A1 and A2 have a sufficient capacity to withstand the amount of grease expelled from the dynamic spaces A3 and A4. In this case, heat generation in the bearing 1 is suppressed, and the effect of extending the lubrication life is obtained. When the ratio of the dynamic space A3+A4 to the total spatial volume is between 30% and 45%, a certain amount of capacity for the static spaces A1 and A2 is ensured for the amount of grease expelled from the dynamic spaces A3 and A4. This suppresses heat generation in the bearing 1 to some extent, and slightly extends the lubrication life.

[0051] If the ratio of the dynamic space A3+A4 to the total spatial volume is greater than 45%, the capacity of the static spaces A1 and A2 will be insufficient for the amount of grease expelled from the dynamic spaces A3 and A4, and the grease will return to the dynamic spaces during use, causing frequent re-entrapment of the grease. If the amount of grease initially injected is limited to suppress heat generation, the lubrication life will be shortened due to insufficient grease.

[0052] (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 pushing aside the grease. If the ratio of stationary spaces A1 + A2 to the total space volume is less than 30%, there is little space for grease to accumulate, and the grease that is blown away returns to the range of the moving spaces A3 and A4, causing frequent heat generation due to grease entrapment. If the amount of grease filled is limited to suppress heat generation, the lubrication life will be shortened due to insufficient grease amount.

[0053] When the ratio of the static space A1+A2 to the total space volume is 30% or more and less than 40%, a certain amount of space is secured for the grease scattered by centrifugal force, etc. Therefore, heat generation in the bearing 1 is suppressed to some extent, and the lubrication life is slightly extended. When the ratio of the static space A1+A2 to the total spatial volume is between 40% and 60%, a sufficient space can be secured to retain the grease that is blown off by centrifugal force, etc. This makes it possible to suppress heat generation in the bearing 1, thereby achieving the effect of extending the lubrication life.

[0054] If the ratio of stationary space A1 + A2 to the total spatial volume is greater than 60%, it is possible to secure sufficient space for the grease scattered by centrifugal force, etc. to remain, and it is possible to suppress heat generation in the bearing 1. However, in this case, the ratio of the tapered rollers 6 to the total spatial volume of the bearing becomes smaller, and the rated load for the bearing dimensions becomes too low, so this is not recommended.

[0055] In addition to satisfying formula (5), the following condition may also be satisfied. 5% x (space volume of stationary space A1 + stationary space A2) < amount of grease filled in the space volume of stationary space A1 + stationary space A2 ≦ 25% x (space volume of stationary space A1 + stationary space A2) By specifying the amount of grease to be filled in the spatial volume of the stationary spaces A1 and A2 in this way, the grease expelled from the moving spaces A3 and A4 can be accommodated in the stationary spaces A1 and A2 with a sufficient margin, which has the effect of suppressing the temperature rise of the bearing caused by the entrainment of grease. It is also possible to further reduce the oil separation rate of the grease in the moving spaces A3 and A4 and the stationary space B. This allows a large amount of base oil to remain in the grease, making it possible to suppress the accelerated deterioration of the oil, and extending the lubrication life.

[0056] In addition to satisfying formula (4), the following condition may also be satisfied. 10% x (space volume of moving space A3 + moving space A4) < amount of grease filled in the space volume of moving space A3 + moving space A4 ≦ 45% x (space volume of moving space A3 + moving space A4) By specifying the amount of grease filled in the spatial volume of the dynamic spaces A3 and A4 in this way, some of the grease is expelled from the dynamic spaces A3 and A4, which has the effect of suppressing the temperature rise of the bearing caused by grease entrapment. It also makes it possible to further reduce the oil separation rate of the grease in the dynamic spaces A3 and A4 and the stationary space B. This allows a large amount of base oil to remain in the grease, making it possible to suppress the acceleration of deterioration of the oil, and extending the lubrication life.

[0057] <Other embodiments> In the following description, parts corresponding to matters previously described in each embodiment are given the same reference numerals, and duplicated description is omitted. When only a part of the configuration is described, the other parts of the configuration are the same as the previously described embodiment unless otherwise specified. The same configuration has the same action and effect. It is possible to combine not only the parts specifically described in each embodiment, but also partially combine embodiments together, provided that there is no particular problem with the combination.

[0058] [Second embodiment: with inner ring spacer, Fig. 5] As shown in Fig. 5, an inner ring spacer 14 may be provided between the two rows of split type inner rings 3, 3. In the case of this bearing 1A, the distance between the load points can be made larger to increase the rigidity of the entire bearing compared to a double row tapered roller bearing not provided with an inner ring spacer, and the spatial volume of the stationary space B can be increased according to the width dimension of the inner ring spacer. In addition, the same effects as those of the above-mentioned embodiment are achieved.

[0059] Instead of the oil slinger 9, a slinger fixed to the outer circumferential surface of the shaft 11 may be used. Instead of the rear cover 10, a slinger fixed to the outer circumferential surface of the shaft 11 may be used. The recesses 5 may be provided at equal intervals around the circumference or at predetermined intervals in the circumferential direction. The recess 5 may be provided at one location on the inner peripheral surface 4a of the outer ring. As the double row rolling bearing, a four row tapered roller bearing may be used. As the double row rolling bearing, an inward facing double row tapered roller bearing may be used. The bearing body, excluding the accessory part 2 and the seal member 8 from the bearing unit BU, can be traded independently on the market.

[0060] [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 FIG. 6. In this case, cylindrical rollers 6A are used as each roller in the double row. The double row cylindrical roller bearing 1B also has a stationary space increasing means 5 that increases the volume of stationary space B, so that the amount of grease remaining in the stationary space is increased compared to a conventional structure that does not have a stationary space increasing means, and the amount of grease sealed inside the bearing can be increased while suppressing the temperature rise caused by grease entrapment. Other effects are the same as those of the first embodiment described above. In addition to railway vehicles, double-row rolling bearings can also be used in industrial machinery and other applications.

[0061] Although the embodiment of the present invention has been described above, the disclosed embodiment is illustrative in all respects and is not restrictive. The scope of the present invention is indicated by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0062] Reference Signs List 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 peripheral surface of outer ring, 5... recess (stationary space increasing means), 6... tapered roller (roller), 6A... cylindrical roller (roller), 7... cage, 8... sealing member, 9... oil thrower, 10... rear cover, 11... axle, 14... inner ring spacer

Claims

1. A double-row rolling bearing used with grease lubrication, an inner ring, an integral outer ring, double rows of rollers provided between the inner and outer rings, a cage for holding these rollers, and seal members provided on both end faces in the axial direction; A double-row rolling bearing comprising: between rows of the inner circumferential surface of the outer ring, a static space increasing means for increasing the volume of the static space in the entire space inside the bearing; the static space increasing means being annular recesses provided on the inner circumferential surface of the outer ring capable of retaining the grease.

2. In the double row rolling bearing according to claim 1, the total space inside the bearing is: a stationary space A1, which is surrounded by the inner and outer rings, the seal member at one end of the bearing, an oil thrower or slinger, and a cage assembly including the rollers and the cage, and which is a space through which the rollers and the cage do not pass when the bearing rotates; a stationary space A2, which is a space through which the rollers and the cage do not pass when the bearing rotates, and which is surrounded by the inner and outer rings, the seal member on the other end side of the bearing, a rear cover or a slinger, and a cage assembly including the rollers and the cage; a stationary space B, which is surrounded by the inner and outer rings and a cage assembly including two rows of rollers and the cage, and which is a space through which the rollers and the cage do not pass when the bearing rotates; and dynamic spaces A3, A4 defined by excluding a volume of the cage assembly at rest from a space through which the cage assembly including the two rows of rollers and the cage passes during rotation, The double-row rolling bearing has the recess provided in the axial center of the inner circumferential surface of the outer ring, which is included in the stationary space B.

3. 3. A double row rolling bearing according to claim 2, 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 space volume ≦ space volume of stationary space B

4. 4. A double-row rolling bearing according to claim 2 or 3, wherein the spatial volume of the space a of the recess has the following relationship with the spatial volume of a stationary space B excluding the space a: 0% x spatial volume of stationary space B excluding a space ≦ spatial volume of a space ≦ 100% x spatial volume of stationary space B excluding a space

5. 4. A double row rolling bearing according to claim 2, wherein the spatial volumes of the dynamic spaces A3 and 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. 4. A double row rolling bearing according to claim 2, wherein the spatial volumes of the stationary spaces A1 and A2 have the following relationship with respect to a total spatial volume inside the bearing: 30% x total space volume ≦ still space A1 + A2 ≦ 60% x total space volume

7. 6. The double-row rolling bearing according to claim 4 or 5, wherein the amount of grease filled in the spatial volume of the stationary space B satisfies the following condition: 20% x spatial volume of stationary space B ≦ amount of grease filled in spatial volume of stationary space B

8. 7. A double-row rolling bearing according to claim 6, wherein the amount of grease filled in the spatial volume of each of the stationary spaces A1 and A2 satisfies the following condition: 5%×(space volume of stationary space A1+stationary space A2)<amount of grease filled in the space volume of stationary space A1+stationary space A2≦25%×(space volume of stationary space A1+stationary space A2)

9. 6. A double row rolling bearing according to claim 5, wherein the amount of grease filled in the spatial volume of each of the dynamic spaces A3 and A4 satisfies the following condition: 10%×(space volume of dynamic space A3+dynamic space A4)<amount of grease filled in the space volume of dynamic space A3+dynamic space A4≦45%×(space volume of dynamic space A3+dynamic space A4)

10. 4. A double-row rolling bearing according to claim 2 or 3, wherein the inner ring is a split-type inner ring, and an inner ring spacer is provided between the two rows of split-type inner rings.

11. 4. A double-row rolling bearing according to claim 2 or 3, which is a bearing for rotatably supporting an axle of a railway vehicle.

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