Double-row rolling bearing

Abstract

The invention relates to a double-row rolling bearing (1), the end faces of the two axial sides of which are sealed and used in a grease lubrication manner. A stationary space increasing means (5) for increasing the volume of a stationary space in the total space inside the bearing is provided between the rows of the outer ring inner peripheral surfaces (4a). The stationary space increasing mechanism (5) is an annular recess which is provided on the inner peripheral surface (4a) of the outer ring and which can hold grease. A double-row rolling bearing (1) is provided with inner rings (3, 3), an integral outer ring (4), double rows of tapered rollers (6, 6) provided between the inner rings and the outer rings (3, 4), retainers (7, 7) for retaining the tapered rollers (6, 6), and seal members (8, 8) provided on end surfaces on both axial sides. A recess is provided in the axial center of the outer ring inner peripheral surface (4a) included in the stationary space (B).

Description

Technical Field

[0001] The present invention relates to a double-row rolling bearing suitable for use in sealed double-row tapered roller bearings and the like, and particularly to a bearing for use in railway vehicles and the like. Background Art

[0002] In recent years, there has been a demand for longer maintenance cycles in axle bearings for railway vehicles. Although extending the lubrication life is necessary, there are concerns that in grease lubrication, if the grease filling amount is increased, the bearing temperature may increase due to grease entrapment. In order to solve these problems, the internal space volume of the bearing is increased, and the grease filling ratio is important.

[0003] The applicant proposed to reduce maintenance time and equipment costs. Figure 7 The bearing device shown in the patent document 1 has an intermediate grease injection mechanism 31, which can provide auxiliary grease 35 for the existing grease filled in the bearing. The intermediate grease injection mechanism 31 fills water into the bag body, and as the bag body ages over time, the water seeps out of the bag body, and the volume of the expansion body 34 increases due to contact with the water. The increase in the volume of the expansion body 34 pushes the auxiliary grease 35 into the interior of the rolling bearing 17.

[0004] The applicant for this case Figure 8 As shown in the patent document 2, a lubrication structure of a rolling bearing is proposed, which can realize maintenance-free and long-term operation (patent document 2). Specifically, in a double-row rolling bearing, an engaging portion that engages with the outer periphery of the inner rings 51, 51 on both sides is provided in the inner ring gasket 50, and a lubricant storage recess 52 is provided on the inner diameter surface across the adjacent ends of the two inner rings 51, 51 and the inner ring gasket 50. A lubricant outflow passage such as a fine hole is provided, which is opened from the lubricant storage recess 52 to the space between the inner and outer rings 51, 53. The lubricant storage recess 52 is filled with grease.

[0005] [Prior art literature]

[0006] [Patent Document]

[0007] Patent Document 1: Japanese Patent Application Publication No. 2020-148321

[0008] Patent Document 2: JP Utility Model Publication No. 6-45117 Summary of the invention

[0009] [Problems to be Solved by the Invention]

[0010] Patent Document 1 states that by adding auxiliary grease midway, the bearing lubrication life can be extended and the vehicle maintenance cycle can be extended. However, the timing of adding auxiliary grease depends on the deterioration of the bag body due to the heating of the bearing, so the material and thickness of the bag body must be carefully checked for each use condition, which makes control complicated. The deteriorated grease inside the bearing will not be discharged to the outside of the bearing, so the following problems will arise. By increasing the grease filling capacity inside the bearing, the chance of temperature rise due to grease entrapment may increase, or stirring the auxiliary grease immediately after replenishment inside the bearing may cause temporary temperature rise of the bearing.

[0011] Patent Document 2 states that a recess is provided at the end of the inner ring adjacent to the inner ring gasket, thereby providing lubrication to the inside of the bearing through the centrifugal force when the inner ring rotates, thereby enabling maintenance-free operation for a longer period of time. However, this shape is only applicable to bearings that are arranged in parallel with the inner ring gasket, and it is believed that there is a possibility that foreign matter may be mixed into the grease filling portion when the bearing is pressed in.

[0012] The object of the present invention is to provide a double-row rolling bearing capable of extending the lubrication life.

[0013] [Methods to solve the problem]

[0014] (Technical Solution 1)

[0015] The double-row rolling bearing of the present invention is a double-row rolling bearing used in a grease-lubricated manner, wherein the double-row rolling bearing comprises: an inner ring, an integral outer ring, double-row rollers arranged between the inner ring and the outer ring, a retainer for holding these rollers, a sealing component arranged on the end faces on both sides of the axial direction, and a static space increasing mechanism, wherein the static space increasing mechanism increases the volume of the static space in the total space inside the bearing between the rows on the inner circumferential surface of the outer ring, and the static space increasing mechanism is an annular recessed portion arranged on the inner circumferential surface of the outer ring that can hold the grease.

[0016] The “stationary space” mentioned above refers to a space in the entire space inside the bearing through which rotating bodies such as rolling elements and cages do not pass when the bearing rotates.

[0017] According to this structure, there is a static space increasing mechanism, which increases the volume of the static space in the total space inside the bearing between the rows of the inner circumference of the outer ring. The static space increasing mechanism is an annular recessed portion that is arranged on the inner circumference of the outer ring and can hold the grease. Therefore, compared with the conventional structure without the static space increasing mechanism, the amount of grease remaining in the static space increases, which can suppress the temperature rise caused by the entrapment of grease, and at the same time increase the amount of grease filled inside the bearing. In addition, during operation, more base oil is left through the grease in the dynamic space and the static space, and the accelerated deterioration of the oil can be suppressed. Therefore, the lubrication life can be extended without changing the internal design of the existing rolling bearing.

[0018] Since the static space increasing mechanism is an annular recessed portion provided on the inner peripheral surface of the outer ring and capable of retaining grease, the recessed portion can be relatively easily provided on the inner peripheral surface of the outer ring by machining or the like.

[0019] (Technical Solution 2)

[0020] Alternatively, the total space inside the bearing may include:

[0021] a stationary space A1, which is surrounded by the inner ring and the outer ring, the sealing member at one end of the bearing, the oil slinger or the oil thrower, and the retainer assembly including the roller and the retainer, and serves as a space through which the roller and the retainer do not pass when the bearing rotates,

[0022] a stationary space A2, which is surrounded by the inner ring and the outer ring, the sealing member at the other end of the bearing, the rear cover or the oil slinger, and the retainer assembly including the rollers and the retainer, and serves as a space through which the rollers and the retainer do not pass when the bearing rotates,

[0023] a stationary space B, which is surrounded by the inner ring and the outer ring, the retainer assembly including two rows of rollers and the retainer, and is a space through which the rollers and the retainer do not pass when the bearing rotates, and

[0024] dynamic spaces A3 and A4, which are obtained by subtracting the volume of the retainer assembly when it is stationary from the space through which the retainer assembly including the two rows of rollers and the retainer rotates,

[0025] The recessed portion is provided at the axial center portion of the inner peripheral surface of the outer ring included in the static space B.

[0026] In this way, the space volume of the stationary space B surrounded by the inner ring and the outer ring, the retainer assembly including two rows of rollers and the retainer can be increased. Therefore, without changing the internal design of the existing double-row roller bearing including the main dimensions, component composition and specifications, the space volume inside the bearing can be increased and the lubrication life can be extended.

[0027] (Technical Solution 3)

[0028] Alternatively, the spatial volume of the static space B may have the following relationship compared with the total spatial volume inside the bearing:

[0029] 15%×total space volume ≤ the space volume of static space B.

[0030] By satisfying the above relationship, it is possible to sufficiently ensure the residual amount of the base oil contained in the grease in the dynamic spaces A3 and A4 and the static space B, thereby suppressing the acceleration of the deterioration of the oil.

[0031] (Technical Solution 4)

[0032] The spatial volume of the space a of the concave portion and the spatial volume of the static space B excluding the space a may have the following relationship:

[0033] 0%×the spatial volume of the static space B minus the space a≤the spatial volume of the space a≤100%×the spatial volume of the static space B minus the space a.

[0034] By satisfying the above relationship, it is possible to sufficiently ensure the residual amount of the base oil contained in the grease in the dynamic spaces A3 and A4 and the static space B, thereby suppressing the acceleration of the deterioration of the oil.

[0035] (Technical Solution 5)

[0036] Alternatively, the spatial volumes of the dynamic space A3 and the dynamic space A4 may have the following relationship compared with the total spatial volume inside the bearing:

[0037] 15%×total space volume ≤ the space volume of dynamic space A3+A4 ≤ 45%×total space volume.

[0038] When the above relationship is satisfied, sufficient capacity of the static spaces A1 and A2 can be ensured for the amount of grease squeezed out of the driven spaces A3 and A4. This suppresses heat generation of the bearings, thereby further extending the lubrication life.

[0039] The grease in the moving spaces A3 and A4 is accumulated in the stationary spaces A1 and A2 due to the scraping of the tapered rollers and the influence of centrifugal force. If the moving spaces A3+A4 account for less than 15% of the total space volume, the amount of grease squeezed out of the moving spaces A3 and A4 is small, and the influence of heat caused by the re-entry of grease is small. However, since the proportion of the tapered roller in the overall space volume of the bearing will decrease, the rated load relative to the bearing size will become too low, so it is not recommended.

[0040] If the ratio of the dynamic space A3+A4 to the total space volume exceeds 45%, the capacity of the static spaces A1 and A2 is insufficient relative to the amount of grease squeezed out from the dynamic spaces A3 and A4, and grease re-entry due to grease returning to the dynamic space side will frequently occur during use. If the initial grease filling amount is limited to suppress heat generation, insufficient grease will occur, resulting in a reduction in lubrication life.

[0041] (Technical Solution 6)

[0042] Alternatively, the spatial volumes of the static space A1 and the static space A2 may have the following relationship compared with the total spatial volume inside the bearing:

[0043] 30%×total space volume ≤ static space A1+A2 ≤ 60%×total space volume.

[0044] When the above relationship is satisfied, a space is secured for the grease scattered by centrifugal force, etc. This can suppress the heating of the bearing and further extend the lubrication life.

[0045] During use, grease will accumulate in the static spaces A1 and A2 due to the influence of centrifugal force and the effect of tapered rollers scraping grease. If the static spaces A1+A2 account for less than 30% of the total space volume, the space for grease accumulation is very small, and the scattered grease will return to the range of the dynamic spaces A3 and A4, causing frequent heating due to grease entrapment. If the amount of grease sealed is limited in order to suppress heat generation, insufficient grease will occur, resulting in a reduction in lubrication life.

[0046] If the static space A1+A2 accounts for more than 60% of the total space volume, sufficient space can be secured for the grease scattered by centrifugal force, etc., and the heating of the bearing can be suppressed. However, in this case, the ratio of the roller to the overall space volume of the bearing will decrease, resulting in a load rating that is too low relative to the bearing size, so it is not recommended.

[0047] (Technical Solution 7)

[0048] Alternatively, the grease filling amount of the space volume of the static space B may satisfy the following conditions:

[0049] 20%×the spatial volume of the static space B≤the grease filling amount of the spatial volume of the static space B.

[0050] In this case, the remaining amount of the base oil contained in the grease in the static space B can be sufficiently and more reliably ensured.

[0051] (Technical Solution 8)

[0052] Alternatively, the grease filling amount of the static space A1 and the static space A2 may satisfy the following conditions:

[0053] 5%×(the spatial volume of the static space A1+the spatial volume of the static space A2)<the grease filling amount of the spatial volume of the static space A1+the static space A2≤25%×(the spatial volume of the static space A1+the static space A2).

[0054] In this way, by defining the grease filling amount of the space volume of the static spaces A1 and A2, the grease squeezed out from the dynamic spaces A3 and A4 is accommodated in a manner that there is a surplus in the static spaces A1 and A2, thereby having the effect of suppressing the increase in bearing temperature caused by the entrapment of grease. In addition, the oil separation rate of the grease in the dynamic spaces A3 and A4 and the static space B can be suppressed to a low level. According to this, a large amount of base oil can remain in the grease, the accelerated deterioration of the oil components can be suppressed, and the lubrication life can be extended.

[0055] (Technical Solution 9)

[0056] Alternatively, the grease filling amount of the above-mentioned dynamic space A3 and the above-mentioned dynamic space A4 may satisfy the following conditions:

[0057] 10%×(spatial volume of dynamic space A3+spatial volume of dynamic space A4)<grease filling amount of spatial volume of dynamic space A3+spatial volume of dynamic space A4≤45%×(spatial volume of dynamic space A3+spatial volume of dynamic space A4).

[0058] In this way, by specifying the grease filling amount of the space volume of the dynamic space A3+dynamic space A4, a part of the grease is ejected from the dynamic spaces A3 and A4, thereby having the effect of suppressing the increase in bearing temperature caused by the entrapment of grease. In addition, the oil separation rate of the grease in the dynamic spaces A3 and A4 and the static space B can be suppressed to a low level. Accordingly, a large amount of base oil can remain in the grease, the accelerated deterioration of the oil components can be suppressed, and the lubrication life can be extended.

[0059] (Technical Solution 10)

[0060] The inner ring is a split inner ring, and an inner ring washer may be provided between the two rows of the split inner rings. In this case, compared with a double-row tapered roller bearing without an inner ring washer, the distance between the action points can be increased, the rigidity of the entire bearing can be improved, and the space volume of the static space B can be increased according to the width of the inner ring washer.

[0061] The inner ring gasket mentioned above is regarded as the “inner ring” when defining the static space B.

[0062] (Technical Solution 11)

[0063] The double row rolling bearing can also be used for supporting the axle of a railway vehicle in a freely rotatable manner. At this time, the lubrication life of the double row rolling bearing as the axle bearing of the railway vehicle can be extended, so compared with the existing railway vehicle, the maintenance cycle can be extended.

[0064] The present invention includes any combination of at least two configurations disclosed in the claims and / or the specification and / or the drawings. In particular, the present invention includes any combination of two or more of the claims in the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] The present invention can be more clearly understood by referring to the following description of suitable embodiments with reference to the accompanying drawings. However, the embodiments and the accompanying drawings are for illustration and description only and should not be used to limit the scope of the present invention. The scope of the present invention is determined by the claims. In the accompanying drawings, the same symbols in multiple drawings represent the same or equivalent parts.

[0066] Figure 1 : It is a longitudinal cross-sectional view of a double-row rolling bearing according to the first embodiment of the present invention.

[0067] Figure 2 :for Figure 1 A partial enlarged view of the area around part II.

[0068] Figure 3 : A graph showing the oil separation rate of grease inside a bearing.

[0069] Figure 4 : A graph showing the oil separation rate of grease inside a bearing.

[0070] Figure 5 : A longitudinal cross-sectional view of a double-row rolling bearing according to a second embodiment of the present invention.

[0071] Figure 6 : A longitudinal cross-sectional view of a double-row rolling bearing according to a third embodiment of the present invention.

[0072] Figure 7 : An enlarged cross-sectional view of the intermediate grease injection mechanism of a known embodiment.

[0073] Figure 8 : A longitudinal cross-sectional view of a double-row tapered roller bearing according to another known embodiment.

[0074] Fig. 9 : Schematic diagram for explaining the durability test of the bearing. DETAILED DESCRIPTION

[0075] [First embodiment]

[0076] The double row rolling bearing of the embodiment of the present invention is Figure 1 to Figure 4 The double row rolling bearing is suitable for use, for example, in a bearing unit for rotatably supporting an axle of a railway vehicle. Figure 1 The double row rolling bearing shown is a double row tapered roller bearing 1. In this specification, the double row tapered roller bearing 1 may be simply referred to as a bearing 1. The bearing unit BU includes a double row tapered roller bearing 1 and attachments 2 provided on both sides of the bearing 1 in the axial direction.

[0077] <General Structure of Double-row Tapered Roller Bearings>

[0078] The double-row tapered roller bearing 1 is sealed on both axial sides and is used in a grease-lubricated manner. The entire space inside the bearing between the inner ring 3 and the outer ring 4 is filled with grease. Figure 2 ) between the rows, and a static space increasing mechanism 5 described later is provided. The above-mentioned bearing is a so-called outward-facing double-row tapered roller bearing 1, which can bear radial loads and axial loads in two directions. Compared with an inward-facing double-row tapered roller bearing of the same bearing size, the above-mentioned outward-facing double-row tapered roller bearing 1 has a longer distance between the action points and can bear a larger moment load.

[0079] The double-row tapered roller bearing 1 has: split inner rings 3, 3; an integral outer ring 4; double-row tapered rollers 6 arranged between the raceway surfaces 3a, 4b of the inner ring 3 and the outer ring 4; a retainer 7 for retaining these tapered rollers 6; and sealing members 8, 8 arranged on the end surfaces on both sides of the axial direction. A pair of retainers 7 is provided for each roller row. The two retainers 7, 7 are arranged to be spaced apart from each other in the axial direction. The inner ring 3 and the outer ring 4 are made of bearing steel or carburized steel.

[0080] <Attachments, etc.>

[0081] The accessory 2 includes, for example, an oil thrower 9 and a rear cover 10. The rear cover 10 is mounted on the axial wheel side of the axle 11 relative to the bearing 1 ( Figure 1The right side is in the middle). A sleeve not shown in the figure is fixed to the outer circumference of the rear cover 10, and a sealing outer ring 12 is fixed to the inner circumference of the outer ring connected to the end face of the outer ring. A sealing member 13 and a sealing ring (not shown) are arranged between the sleeve and the sealing outer ring 12. Sometimes there is no sealing ring. The sealing member 13 is mounted on the sealing outer ring 12, and together with the sealing outer ring 12 and the sealing ring, it forms a sealing component 8. The sealing member 13 is in sliding contact with the sleeve, and the sealing ring is mounted on the sealing outer ring 12, and forms a labyrinth seal with the sleeve. If there is no sealing ring, the sealing member 13 is in direct sliding contact with the rear cover 10 to form a seal.

[0082] The oil retaining ring 9 is installed on one side of the shaft end of the axle 11. Like the rear cover 10, the outer peripheral surface of the oil retaining ring 9 is also fixed with a sleeve not shown in the figure, and the sealing outer ring 12 is fixed to the inner peripheral surface of the outer ring. Between the above-mentioned sleeve and the sealing outer ring 12, a sealing member 13 and a sealing ring not shown in the figure are provided. The sealing member 13 is installed on the sealing outer ring 12, and together with the sealing outer ring 12 and the sealing ring, it constitutes a sealing component 8. The sealing member 13 is in sliding contact with the sleeve, and the sealing ring is installed on the sealing outer ring 12, and a labyrinth seal is formed between it and the above-mentioned sleeve. Like the rear cover, the oil retaining ring 9 may also be without a sealing ring.

[0083] <About the total space inside the bearing>

[0084] The total space inside the annular bearing is set between the inner ring outer circumference 3b and the outer ring inner circumference 4a. The total space inside the bearing includes: static space A1, static space A2, static space B and dynamic spaces A3 and A4. The total space inside the bearing is also referred to as "bearing space". The total space volume inside the bearing is the volume of static space A1, A2 + static space B + dynamic space A3 and A4. The static space A1 is an annular space surrounded by the inner ring 3 and the outer ring 4, the sealing component 8 on one end of the bearing, the oil retainer 9 and the retainer assembly including the tapered roller 6 and the retainer 7. It is a space that the tapered roller 6 and the retainer 7 do not pass through when the bearing rotates.

[0085] The stationary space A2 is an annular space surrounded by the inner ring 3 and the outer ring 4, the sealing component 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. It is a space through which the tapered rollers 6 and the retainer 7 do not pass when the bearing rotates.

[0086] The stationary space B is a space surrounded by the inner ring 3, the outer ring 4 and the retainer assembly including two rows of tapered rollers 6, 6 and retainers 7, 7. When the bearing rotates, the tapered rollers 6 and the retainer 7 do not pass through this space.

[0087] The dynamic spaces A3 and A4 are the dynamic spaces obtained by subtracting the volume of the retainer assembly when it is stationary from the space through which the retainer assembly including the two rows of tapered rollers 6, 6 and retainers 7, 7 passes when rotating. The dynamic space A3 is the space of the row adjacent to the stationary space A1 on one side, and the dynamic space A4 is the space of the row adjacent to the stationary space A2 on the other side.

[0088] <Stationary Space Increase Mechanism>

[0089] The static space increasing mechanism 5 increases the volume of the static space in the total space inside the bearing by only the amount of space a. Figure 2 As shown, the static space increasing mechanism 5 is an annular recessed portion that is arranged on the inner circumference 4a of the outer ring and can retain grease. In other words, space a is the space formed by the recessed portion 5. A recessed portion 5 having a rectangular hole-like cross section is arranged in the axial central portion of the inner circumference 4a of the outer ring included in the static space B. By providing space a of the recessed portion 5 in the axial central portion of the inner circumference 4a of the outer ring for grease replenishment, the grease filling amount of the total space inside the bearing can be increased without changing the main dimensions, component structure and specifications of the bearing, thereby extending the lubrication life. The above-mentioned main dimensions refer to Figure 1 The inner diameter, outer diameter and width dimensions of the bearing 1 are shown. The above specifications refer to the rated load of the bearing 1, the load direction that can be sustained, etc.

[0090] <parameters>

[0091] The space surrounded by the inner ring outer circumferential surface 3b, the outer ring inner circumferential surface 4a and the seal members 8, 8 of the bearing 1 is designed to satisfy the following conditions except for the volumes of the retainers 7, 7 and the tapered rollers 6.

[0092] (1) 15% × total space volume ≤ space volume of static space B

[0093] (2) 0% × the volume of the static space B minus the space a ≤ the volume of the space a ≤ 100% × the volume of the static space B minus the space a

[0094] (3) 20% × the volume of static space B ≤ the amount of grease filled in the volume of static space B

[0095] (4) 15% × total space volume ≤ dynamic space A3 + A4 space volume ≤ 45% × total space volume

[0096] (5) 30% × total space volume ≤ static space A1 + A2 ≤ 60% × total space volume

[0097] [Example]

[0098] The effect obtained by satisfying the above formula was evaluated as follows.

[0099] [Table 1]

[0100] (1) 15% × total space volume ≤ static space volume B

[0101] (3) 20% × static space volume B ≤ grease filling amount of static space volume B

[0102]

[0103] ◎: Good effect

[0104] ○: Effective

[0105] ×: No effect

[0106] [Table 2]

[0107] (2) 0% × the volume of the static space B after removing a ≤ the volume of the space a ≤ 100% × the volume of the static space B after removing a

[0108] Even within the above range, the effect is better when it is within the following range:

[0109] 5% × the volume of the static space B after removing a ≤ the volume of the space a ≤ 30% × the volume of the static space B after removing a

[0110] The ratio of the spatial volume of space a to the static spatial volume B determination ~Less than 5% ○ More than 5% and less than 30% ◎◎ More than 30%, less than 100% ◎

[0111] ◎: The effect of slowing down the remaining amount of base oil contained in the grease of the dynamic space A3+dynamic space A4+static space B and the accelerated deterioration of the base oil is great.

[0112] ◎◎: Better results than ◎

[0113] ○: Effective in slowing down the remaining amount of base oil contained in the grease of the dynamic space A3 + dynamic space A4 + static space B and the accelerated deterioration of the base oil

[0114] <Durability test (1)>

[0115] A durability test of bearing 1 was conducted. The test conditions are shown in Table 3. The test bearings and the initial grease seal amount (initial grease coating amount) are shown in Table 4. "Dmn" in Table 3 is the value obtained by multiplying the pitch circle diameter Dm (unit: mm) of the bearing 1 by the number of revolutions n (unit: rpm) of the inner ring 3. The above pitch circle diameter Dm is calculated by (inner ring inner diameter + outer ring outer diameter) / 2. "Cr" is the basic rated dynamic load, and "conditions equivalent to EN12082" are conditions for continuous operation of the bearing 1 with the main dimensions below the specified period (e.g., 7 to 8 months).

[0116] Inner ring inner diameter φ130mm × outer ring outer diameter φ240mm × width 160mm

[0117] [Table 3]

[0118] Table 3 Durability test conditions

[0119]

[0120] [Table 4]

[0121] Table 4 Specifications of test bearings and initial grease application amount (ratio to space volume)

[0122] Name of product The ratio of the spatial volume of space a to the static spatial volume B Example X ~Less than 10% Example Y More than 10%, less than 100%

[0123] Figure 3 The oil separation rate inside the bearing after the above-mentioned durability test is shown. The above-mentioned "oil separation rate" is calculated by the following formula.

[0124] Oil separation rate (%) = {(mass of oil in new grease - mass of oil in used grease) / mass of oil in new grease} × 100

[0125] In Example Y, in which the ratio of the spatial volume of the "a" space to the spatial volume of the static space B is more than 10% but less than 100%, the oil separation rate is lower and the base oil residual rate is higher in each part of the dynamic space A3, A4 and the static space a than in Example X.

[0126] [Table 5]

[0127] (5) 30% × total space volume ≤ static space A1 + static space A2 ≤ 60% × total space volume.

[0128] Furthermore, the grease filling amount of the space volume in the static space A1 and the static space A2 satisfies the following conditions.

[0129] 5%×(the spatial volume of the static space A1+the spatial volume of the static space A2)<the grease filling amount of the spatial volume of the static space A1+the static space A2≤25%×(the spatial volume of the static space A1+the static space A2).

[0130] The ratio of static space A1 + static space A2 to the total space volume determination ~Less than 30% × More than 30%, less than 40% △ More than 40% and less than 60% 〇 More than 60%~ ▲

[0131] ○: Has the effect of extending the lubrication life

[0132] Δ: Has some effect of extending lubrication life

[0133] ▲: Although the lubrication life is extended, the bearing load rating becomes too low

[0134] ×: No effect on extending lubrication life

[0135] [Table 6]

[0136] (4) 15% × total space volume ≤ dynamic space A3 + dynamic space A4 ≤ 45% × total space volume

[0137] Furthermore, the grease filling amount of the spatial volume in the dynamic space A3 and the dynamic space A4 satisfies the following conditions.

[0138] 10%×(spatial volume of dynamic space A3+spatial volume of dynamic space A4)<grease filling amount of spatial volume of dynamic space A3+spatial volume of dynamic space A4≤45%×(spatial volume of dynamic space A3+spatial volume of dynamic space A4).

[0139] The ratio of dynamic space A3 + dynamic space A4 to the total space volume determination ~Less than 15% ▲ More than 15%, less than 30% ○ More than 30% and less than 45% Δ Greater than 45% ×

[0140] ○: Has the effect of extending the lubrication life

[0141] Δ: Has some effect of extending lubrication life

[0142] ▲: Although the lubrication life is extended, the bearing load rating becomes too low

[0143] ×: No effect on extending lubrication life

[0144] <Durability test (2)>

[0145] The durability test of the bearing 1 was carried out. The test conditions were the same as those shown in Table 3. The test bearings and the initial grease seal amount (initial grease application amount) are shown in Table 7.

[0146] [Table 7]

[0147] Table 7 Specifications of test bearings and initial grease application amount (ratio to space volume)

[0148] Name of product Still Space A1+A2 Still Space B Dynamic Space A3+A4 Example X 0％ 60％ 20％ Example Y 20％ 40％ 20％

[0149] The bearing temperature data of the endurance test was obtained. For the bearing temperature, the temperature of the outer ring, for example, which is a fixed ring, was measured. 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 as follows: Figure 4 The oil separation rate is similar to the above Figure 3 As in formula (5) and formula (4), in Example Z where the initial grease application amount is changed, there is an effect of suppressing the increase in bearing temperature, and, as Figure 4 Thus, the oil separation rate is lower than that of Example Y in each of the static space A1+A2, the static space B, and the dynamic space A3+A4.

[0150] [Table 8]

[0151] Table 8 Average temperature ratio of bearings

[0152] Average temperature ratio, ℃ Y 1 Z 0.8

[0153] <Effects>

[0154] The double-row rolling bearing 1 described above has a static space increasing mechanism 5, which increases the volume of the static space B in the total space inside the bearing between the rows of the inner peripheral surface 4a of the outer ring. Therefore, compared with the conventional structure without the static space increasing mechanism, the amount of grease remaining in the static space increases, which can suppress the temperature rise caused by the entrapment of grease and increase the amount of grease filled inside the bearing. In addition, during operation, more base oil remains through the grease in the dynamic spaces A3, A4 and the static space B, and the accelerated deterioration of the oil content can be suppressed. Therefore, the lubrication life can be extended without changing the internal design of the existing rolling bearing.

[0155] The static space increasing mechanism is an annular recessed portion 5 provided on the inner peripheral surface 4a of the outer ring and capable of retaining grease. Therefore, the recessed portion 5 can be provided on the inner peripheral surface 4a of the outer ring relatively easily by machining or the like.

[0156] The above-mentioned recess 5 is provided in the axial center of the inner peripheral surface 4a of the outer ring included in the static space B, and the static space B is surrounded by the inner ring 3 and the outer ring 4, and the retainer assembly including two rows of tapered rollers 6, 6 and retainers 7, 7. Therefore, the spatial volume of the static space B can be increased. Therefore, the spatial volume inside the bearing can be increased without changing the internal design including the main dimensions, component structure and specifications of the existing double-row tapered roller bearing. Accompanying this, the ratio of the static space to the total space inside the bearing increases, and the amount of grease that is not involved in the rotation can be increased. By increasing the remaining amount of base oil contained in the grease remaining in the dynamic space A3+dynamic space A4+static space B that affects the rotation, the accelerated deterioration of the oil components can be suppressed, and the lubrication life can be extended.

[0157] In order to obtain the above-mentioned effects to a large extent, it is preferable that all of the following formulas (1), (2) and (3) are satisfied.

[0158] (1) 15% × total space volume ≤ space volume of static space B

[0159] (2) 0% × the volume of the static space B minus the space a ≤ the volume of the space a ≤ 100% × the volume of the static space B minus the space a

[0160] (3) 20% × the volume of static space B ≤ the amount of grease filled in the volume of static space B

[0161] (4) 15% × total space volume ≤ dynamic space A3 + A4 space volume ≤ 45% × total space volume

[0162] The grease in the moving spaces A3 and A4 is accumulated in the stationary spaces A1 and A2 due to the scraping of the tapered roller 6 and the influence of the centrifugal force. If the ratio of the moving spaces A3+A4 to the total space volume is less than 15%, the amount of grease squeezed out of the moving spaces A3 and A4 is small, and the influence of heat generation caused by the re-entry of grease is also small. However, since the ratio of the tapered roller 6 to the overall space volume of the bearing will be reduced, the rated load relative to the bearing size will become too low, so it is not recommended.

[0163] When the ratio of the dynamic space A3+A4 to the total space volume is greater than 15% and less than 30%, the amount of grease squeezed out from the dynamic spaces A3 and A4 can ensure sufficient capacity of the static spaces A1 and A2. At this time, the heating of the bearing 1 is suppressed, thereby obtaining an effect of extending the lubrication life.

[0164] When the ratio of the dynamic space A3+A4 to the total space volume is greater than 30% and less than 45%, the capacity of the static spaces A1 and A2 is ensured to a certain extent relative to the amount of grease squeezed out from the dynamic spaces A3 and A4. Therefore, the heating of the bearing 1 can be suppressed to a certain extent, and the lubrication life can be extended to a certain extent.

[0165] When the ratio of the dynamic space A3+A4 to the total space volume exceeds 45%, the capacity of the static spaces A1 and A2 is insufficient relative to the amount of grease squeezed out from the dynamic spaces A3 and A4, and grease re-entry due to grease returning to the dynamic space side will frequently occur during use. If the initial grease filling amount is limited to suppress heat generation, the lubrication life will be shortened due to insufficient grease.

[0166] (5) 30% × total space volume ≤ static space A1 + A2 ≤ 60% × total space volume

[0167] During use, due to the influence of centrifugal force and the influence of tapered roller 6 scraping grease, grease will accumulate in the static spaces A1 and A2. If the static space A1+A2 accounts for less than 30% of the total space volume, the space for grease accumulation is very small, and the scattered grease will return to the range of the dynamic spaces A3 and A4, and heat caused by grease entrapment will frequently occur. If the filling amount of grease is limited in order to suppress heat generation, the lubrication life will be shortened due to insufficient grease.

[0168] When the static space A1+A2 accounts for more than 30% and less than 40% of the total space volume, it can ensure a certain amount of space for the grease scattered by centrifugal force, etc. Thus, the heating of the bearing 1 can be suppressed to a certain extent, and the lubrication life can be extended to some extent.

[0169] When the static space A1+A2 accounts for 40% or more and 60% or less of the total space volume, sufficient space can be secured for the grease scattered by centrifugal force, etc. This can suppress the heating of the bearing 1 and extend the lubrication life.

[0170] If the ratio of the static space A1+A2 to the total space volume exceeds 60%, sufficient space can be secured for the grease scattered by centrifugal force, etc., thereby suppressing the heating of the bearing 1. However, in this case, since the ratio of the space volume of the tapered roller 6 to the entire bearing is reduced, the rated load relative to the bearing size becomes too low, so it is not recommended.

[0171] While satisfying equation (5), the following conditions can also be satisfied.

[0172] 5%×(the spatial volume of the static space A1+the spatial volume of the static space A2)<the grease filling amount of the spatial volume of the static space A1+the static space A2≤25%×(the spatial volume of the static space A1+the static space A2).

[0173] In this way, by specifying the grease filling amount of the space volume of the static spaces A1 and A2, the grease squeezed out from the dynamic spaces A3 and A4 is accommodated in a manner that there is a surplus in the static spaces A1 and A2, thereby having the effect of suppressing the increase in bearing temperature caused by the entrapment of grease. In addition, the oil separation rate of the grease in the dynamic spaces A3 and A4 and the static space B can be suppressed to a low level. According to this, a large amount of base oil can remain in the grease, the acceleration of oil deterioration can be suppressed, and the lubrication life can be extended.

[0174] While satisfying equation (4), the following conditions can also be satisfied.

[0175] 10%×(spatial volume of dynamic space A3+spatial volume of dynamic space A4)<grease filling amount of spatial volume of dynamic space A3+spatial volume of dynamic space A4≤45%×(spatial volume of dynamic space A3+spatial volume of dynamic space A4).

[0176] In this way, by defining the grease filling amount of the space volume of the dynamic space A3+dynamic space A4, a part of the grease is ejected from the dynamic spaces A3 and A4, thereby having the effect of suppressing the increase in bearing temperature caused by the entrapment of grease. In addition, the oil separation rate of the grease in the dynamic spaces A3 and A4 and the static space B can be suppressed to a low level. Accordingly, a large amount of base oil can remain in the grease, the acceleration of oil deterioration can be suppressed, and the lubrication life can be extended.

[0177] <About other implementation forms>

[0178] In the following description, the parts corresponding to the matters previously described in each embodiment are marked with the same reference numerals, and repeated descriptions are omitted. When only a part of the structure is described, unless otherwise specified, the other parts of the structure should be the same as the previously described embodiment. The same structure produces the same effect. Not only the combination of the parts specifically described in each embodiment, but also partial combination between embodiments is possible if there is no special obstacle to the combination.

[0179] [Second embodiment: with inner ring washer, Figure 5 ]

[0180] like Figure 5 As shown, an inner ring washer 14 can be provided between the two rows of split inner rings 3, 3. In the case of such a bearing 1A, the distance between the action points can be increased compared to a double-row tapered roller bearing without an inner ring washer, thereby improving the overall rigidity of the bearing, and the spatial volume of the static space B can be increased according to the width dimension of the inner ring washer. In addition, the same effects as those of the above-mentioned embodiment can be achieved.

[0181] Instead of the oil slinger 9, an oil slinger fixed to the outer peripheral surface of the shaft 11 or the like may be used.

[0182] Instead of the rear cover 10 , an oil slinger fixed to the outer peripheral surface of the shaft 11 or the like may be used.

[0183] The recessed portions 5 may be arranged evenly around the circumference or at predetermined intervals in the circumferential direction. The recessed portion 5 may be arranged at one position of the inner circumferential surface 4a of the outer ring.

[0184] As a double-row rolling bearing, a four-row tapered roller bearing may be used.

[0185] As the double-row rolling bearing, an inward-type double-row tapered roller bearing may be used.

[0186] The bearing main body excluding the attachment 2 and the sealing member 8 from the bearing unit BU can be traded independently on the market.

[0187] [Third embodiment: double row cylindrical roller bearing]

[0188] As double row rolling bearings, Figure 6 As shown in the figure, it can be used as a double-row cylindrical roller bearing 1B. In this case, cylindrical rollers 6A are used as the double-row rollers. The double-row cylindrical roller bearing 1B is also equipped with a static space increasing mechanism 5 for increasing the volume of the static space B. Therefore, compared with the conventional structure without the static space increasing mechanism, the remaining grease in the static space is increased, and the temperature rise caused by the entrapment of grease can be suppressed, and the grease filling amount inside the bearing can be increased. The same effects as those of the first embodiment described above are produced.

[0189] In addition to railway vehicles, double-row rolling bearings can also be used in industrial machinery and other fields.

[0190] As described above, while referring to the drawings, suitable embodiments have been described, but various additions, changes and deletions may be made without departing from the gist of the present invention. Therefore, these changes should also be included in the scope of the present invention.

[0191] [Explanation of symbols]

[0192] 1. 1A...Double-row tapered roller bearings (double-row rolling bearings)

[0193] 1B...Double row cylindrical roller bearings (double row rolling bearings)

[0194] 3…Inner Circle

[0195] 4...Outer ring

[0196] 4a...Inner circumference of outer ring

[0197] 5... Recessed part (static space increasing mechanism)

[0198] 6...Tapered roller (roller)

[0199] 6A...Cylindrical roller

[0200] 7. Retainer

[0201] 8... Sealing parts

[0202] 9...Oil retaining ring

[0203] 10... Back cover

[0204] 11…Axle

[0205] 14...Inner ring gasket.

Claims

1. A double-row rolling bearing used in a grease-lubricated manner, wherein: The double-row rolling bearing comprises: an inner ring, an integral outer ring, double-row rollers arranged between the inner ring and the outer ring, a retainer for holding the rollers, a sealing component arranged on the end faces on both sides of the axial direction, and a static space increasing mechanism, which increases the volume of the static space in the total space inside the bearing between the rows on the inner circumferential surface of the outer ring, and the static space increasing mechanism is an annular recessed portion arranged on the inner circumferential surface of the outer ring and capable of holding the grease.

2. The double row rolling bearing according to claim 1, characterized in that: The total space inside the above bearing includes: a stationary space A1, which is surrounded by the inner ring and the outer ring, the sealing member at one end of the bearing, the oil slinger or the oil thrower, and the retainer assembly including the roller and the retainer, and serves as a space through which the roller and the retainer do not pass when the bearing rotates, a stationary space A2, which is surrounded by the inner ring and the outer ring, the sealing member at the other end of the bearing, the rear cover or the oil slinger, and the retainer assembly including the rollers and the retainer, and serves as a space through which the rollers and the retainer do not pass when the bearing rotates, a stationary space B, which is surrounded by the inner ring and the outer ring, the retainer assembly including two rows of rollers and the retainer, and is a space through which the rollers and the retainer do not pass when the bearing rotates, and dynamic spaces A3 and A4, which are obtained by subtracting the volume of the retainer assembly when it is stationary from the space through which the retainer assembly including the two rows of rollers and the retainer rotates, The recessed portion is provided at the axial center portion of the inner peripheral surface of the outer ring included in the static space B.

3. The double row rolling bearing according to claim 2, characterized in that: The spatial volume of the static space B mentioned above has the following relationship compared with the total spatial volume inside the bearing: 15%×total space volume ≤ the space volume of static space B.

4. The double row rolling bearing according to claim 2 or 3, characterized in that: The spatial volume of the space a of the concave portion and the spatial volume of the static space B excluding the space a have the following relationship: 0%×the spatial volume of the static space B minus the space a≤the spatial volume of the space a≤100%×the spatial volume of the static space B minus the space a.

5. The double row rolling bearing according to claim 2 or 3, characterized in that: The spatial volumes of the dynamic spaces A3 and A4 are compared with the total spatial volume inside the bearing, and have the following relationship: 15%×total space volume ≤ the space volume of dynamic space A3+A4 ≤ 45%×total space volume.

6. The double row rolling bearing according to claim 2 or 3, characterized in that: The spatial volumes of the static space A1 and the static space A2 are compared with the total spatial volume inside the bearing, and have the following relationship: 30%×total space volume ≤ static space A1+A2 ≤ 60%×total space volume.

7. The double row rolling bearing according to claim 4 or 5, characterized in that: The grease filling amount of the space volume of the static space B satisfies the following conditions: 20%×the spatial volume of the static space B≤the grease filling amount of the spatial volume of the static space B.

8. The double row rolling bearing according to claim 6, characterized in that: The grease filling amount of the space volume of the static space A1 and the static space A2 satisfies the following conditions: 5%×(the spatial volume of the static space A1+the spatial volume of the static space A2)<the grease filling amount of the spatial volume of the static space A1+the static space A2≤25%×(the spatial volume of the static space A1+the static space A2).

9. The double row rolling bearing according to claim 5, characterized in that: The grease filling amount of the space volume of the above-mentioned dynamic space A3 and the above-mentioned dynamic space A4 meets the following conditions: 10%×(spatial volume of dynamic space A3+spatial volume of dynamic space A4)<grease filling amount of spatial volume of dynamic space A3+spatial volume of dynamic space A4≤45%×(spatial volume of dynamic space A3+spatial volume of dynamic space A4).

10. The double row rolling bearing according to claim 2 or 3, characterized in that: The inner ring is a split inner ring, and an inner ring gasket is provided between the two rows of split inner rings.

11. The double row rolling bearing according to claim 2 or 3, characterized in that: The double-row rolling bearing is a bearing used for rotatably supporting an axle of a railway vehicle.

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