Double-row angular contact ball bearing

Abstract

To provide a double row angular ball bearing which is excellent in axial loading capability and moment loading capability, and capable of sufficiently securing a space for a cage to be arranged therein or good in assemblability (ball inserting property).SOLUTION: A double row angular ball bearing 1' includes an outer ring 2' used for a pump and having outer ring raceway surfaces 2a' on the inner periphery, an inner ring 3 having inner ring raceway surfaces 3a on the outer periphery, and a plurality of rolling elements 4 arranged between each outer ring raceway surface 2a' and each inner ring raceway surface 3a, the outer ring raceway surfaces 2a' plurally neighboring each other in the axial direction, the inner ring raceway surfaces 3a plurally neighboring each other in the axial direction, the inner ring 3 being split in the axial direction.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a double-row angular ball bearing, and particularly to a double-row angular ball bearing used in a pump (for example, a hydrogen circulation pump).

Background Art

[0002] In devices having a rotating mechanism, various bearings are used according to the application. As common bearings, rolling bearings such as deep groove ball bearings, angular ball bearings, and tapered roller bearings are known. An angular ball bearing can receive a radial load and an axial load in one direction. In an angular ball bearing, the balls (rolling elements) and the inner and outer rings have a contact angle, and the larger the contact angle, the greater the load capacity for receiving the axial load.

[0003] A double-row angular ball bearing is known as a bearing that can receive axial loads in both directions and also has a load capacity for moment loads. As a double-row angular ball bearing, for example, a structure in which single-row angular ball bearings are back-to-back combined and the inner and outer rings are integrated is known. As this double-row angular ball bearing, for example, a structure in which the shoulder height of the shoulder portion on the side receiving the load of the raceway ring is increased is known (Patent Document 1).

[0004] Conventionally, a double-row angular ball bearing has been used as a rolling bearing used in, for example, a pump or a compressor. For example, Patent Document 2 discloses that a double-row angular ball bearing is used in a roots-type hydrogen circulation pump for a fuel cell. Specifically, in the pump, two rotating shafts arranged so as to protrude from the gear chamber side into the rotor chamber are rotatably supported by double-row angular ball bearings. Further, a drive rotor or a driven rotor is attached to one side of these rotating shafts, and a drive gear or a driven gear is attached to the other side.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Application Publication No. 8-270644 [Patent Document 2] Japanese Patent Publication No. 2021-127736 [Overview of the project] [Problems that the invention aims to solve]

[0006] Incidentally, in the case of a fluid machine (for example, a hydrogen circulation pump) that has a drive gear and drive rotor connected to a motor, a driven gear that meshes with the drive gear, and a driven rotor that meshes with the drive rotor, loads are applied between the drive gear and the driven gear, and between the drive rotor and the driven rotor. For this reason, bearings used in such applications are considered to require particularly high axial load capacity and moment load capacity (moment resistance).

[0007] In double-row angular contact ball bearings, if an excessive axial load is applied, a low groove shoulder height can cause the balls to ride up, potentially leading to delamination or other damage. Therefore, a higher groove shoulder height is advantageous in preventing this riding up. However, if the groove shoulder height is too high, it becomes difficult to secure space for the cage. Furthermore, it is thought that inserting the balls between the raceways becomes difficult during bearing assembly. For example, while Patent Document 1 describes increasing the groove shoulder height of the inner ring and the outer ring, it does not provide a suitable design to address the above-mentioned problems.

[0008] This invention has been made in view of these circumstances, and aims to provide a double-row angular contact ball bearing that has excellent axial load capacity and moment load capacity, as well as sufficient space for arranging the cage, or good assembly (ball insertion). [Means for solving the problem]

[0009] The double-row angular contact ball bearing of the present invention is used in a hydrogen circulation pump and comprises an outer ring having an outer ring raceway on its inner circumference, an inner ring having an inner ring raceway on its outer circumference, and a plurality of rolling elements arranged between the outer ring raceway and the inner ring raceway, with a plurality of the above outer ring raceway and inner ring raceway surfaces. The double-row angular contact ball bearing is characterized in that at least one of the raceway rings of the outer ring and the inner ring is divided in the axial direction.

[0010] The above-described double-row angular contact ball bearing is characterized in that one of the raceways, either the outer ring or the inner ring, is a separable raceway divided in the axial direction, while the other raceway is an integrated raceway having multiple raceway surfaces.

[0011] The above-described double-row angular contact ball bearing has two rows in which the outer ring raceway surface and the inner ring raceway surface face each other, and the direction of the contact angle of the rolling elements in each row is different from that of the other. Furthermore, it is characterized in that the arrangement is a back-to-back combination.

[0012] Shoulders are formed on the inner circumference of the outer ring and the outer circumference of the inner ring, respectively, and the height hD of the shoulder of the outer ring satisfies the following formula (1), and the height hd of the shoulder of the inner ring satisfies the following formula (2). 0.15×(Dα-dp)≦hD≦0.35×(Dα-dp)···(1) 0.15×(dp-dα)≦hd≦0.35×(dp-dα)···(2) Dα: Diameter of the contact point between the outer ring and the rolling element. dα: Diameter of the contact point between the rolling element and the inner ring. dp: Pitch diameter of the rolling element mentioned above

[0013] The diameter Db of the rolling element and the axial width Wb of the double-row angular contact ball bearing satisfy the following relationship (3). 1.1 ≤ Wb / (Db × 2) ≤ 1.7 ···(3)

[0014] The filling ratio γ of the rolling elements arranged in one row of the raceway, as expressed by the following formula (4), is characterized by being 0.65 to 0.90. γ = (Db × Z) / (dp × π) ... (4) Db: Diameter of the rolling element mentioned above Z: Number of rolling elements as described above dp: Pitch diameter of the rolling element mentioned above

[0015] The above-described double-row angular contact ball bearing is characterized by rotatably supporting a rotating shaft to which a rotor that engages with a mating rotor is connected at one end, and a gear that engages with a mating gear is connected at the other end.

[0016] The double-row angular contact ball bearing of the present invention is used in a hydrogen circulation pump and comprises an outer ring having an outer ring raceway on its inner circumference, an inner ring having an inner ring raceway on its outer circumference, and a plurality of rolling elements arranged between the outer ring raceway and the inner ring raceway, with multiple outer ring raceway surfaces and inner ring raceway surfaces. The double-row angular contact ball bearing is characterized in that shoulders are formed on the inner circumference of the outer ring and the outer circumference of the inner ring, the height hD of the shoulder of the outer ring satisfies the following formula (5), and the height hd of the shoulder of the inner ring satisfies the following formula (6). 0.15×(Dα-dp)≦hD≦0.35×(Dα-dp)···(5) 0.15×(dp-dα)≦hd≦0.35×(dp-dα)···(6) Dα: Diameter of the contact point between the outer ring and the rolling element. dα: Diameter of the contact point between the rolling element and the inner ring. dp: Pitch diameter of the rolling element mentioned above [Effects of the Invention]

[0017] The double-row angular contact ball bearing of the present invention is used in hydrogen circulation pumps and has multiple outer ring raceways and inner ring raceways. At least one of the outer and inner ring raceways is divided axially, meaning that either the inner or outer ring is separated into left and right halves. Therefore, when assembling the bearing, the rolling elements can be assembled from the side of the bearing along with the divided raceways. As a result, more rolling elements can be arranged, increasing the rated load. This results in excellent axial load capacity, moment load capacity, and ease of assembly.

[0018] The double-row angular contact ball bearing has a split-type raceway ring in which one of the raceway rings of the outer ring and the inner ring is axially split, and the other raceway ring is an integral-type raceway ring having a plurality of raceway surfaces. Therefore, it has better assembling property than the case where both the inner ring and the outer ring are separable raceway rings (when single-row angular contact ball bearings are combined). Further, since the width dimension in the axial direction of the bearing can be made smaller than the case where single-row angular contact ball bearings are combined, it is easy to save space.

[0019] The double-row angular contact ball bearing has two rows of raceways where the outer-ring raceway surface and the inner-ring raceway surface face each other, and the directions of the contact angles of the rolling elements in each row are different from each other. Therefore, it can receive bidirectional axial loads. Further, since the arrangement is a back-to-back combination, the distance between the action points is larger and the moment load capacity can be further improved compared to a face-to-face combination (DF).

[0020] Shoulders are respectively formed on the inner circumference of the outer ring and the outer circumference of the inner ring, and the height hD of the shoulder of the outer ring satisfies the above formula (1), and the height hd of the shoulder of the inner ring satisfies the above formula (2). Therefore, it is difficult for the rolling elements to ride over the shoulders, and it is easy to sufficiently secure the space for arranging the cage.

[0021] Since the diameter Db of the rolling element and the axial width Wb of the double-row angular contact ball bearing satisfy the relationship of the above formula (3), the diameter Db of the rolling element can be maintained, and the strength of the shoulder and the rated load can be ensured. Also, the axial width Wb is suppressed, which can contribute to downsizing.

[0022] Since the filling ratio γ of the rolling elements arranged in one row of the raceway, represented by the above formula (4), is 0.65 to 0.90, the rated load can be made larger than that of a non-separable double-row angular contact ball bearing for both the inner ring and the outer ring. Also, sufficient space for arranging the cage can be ensured, and the column width between the pockets (circumferential direction) of the cage does not become too small, so that a decrease in the strength of the cage can be suppressed.

[0023] The double-row angular contact ball bearing of the present invention is used in hydrogen circulation pumps and has multiple rows of raceways where the outer ring raceway surface and the inner ring raceway surface face each other. Shoulders are formed on the inner circumference of the outer ring and the outer circumference of the inner ring, respectively. The height hD of the shoulder of the outer ring satisfies equation (5) above, and the height hd of the shoulder of the inner ring satisfies equation (6) above. As a result, it has excellent axial load capacity and moment load capacity, and sufficient space can be secured for arranging the cage. [Brief explanation of the drawing]

[0024] [Figure 1] This is a longitudinal cross-sectional view of a first embodiment of the double-row angular contact ball bearing of the present invention. [Figure 2] This is a longitudinal cross-sectional view of a second embodiment of the double-row angular contact ball bearing of the present invention. [Figure 3] Figure 2 is a partial cross-sectional view of a double-row angular contact ball bearing. [Figure 4] This is a cross-sectional view of a hydrogen circulation pump using the double-row angular contact ball bearings of the present invention. [Modes for carrying out the invention]

[0025] The double-row angular contact ball bearing of the present invention has multiple outer ring raceway surfaces and inner ring raceway surfaces, and at least one of the outer ring and inner ring raceway surfaces is divided in the axial direction, resulting in three configurations depending on how the raceway surfaces are divided. Specifically, there is a configuration in which multiple single-row angular contact ball bearings are combined in parallel (see Figure 1), a configuration in which the outer ring is integrated and the inner ring is separate (see Figure 2), and a configuration in which the inner ring is integrated and the outer ring is separate. These configurations will be described in detail below with reference to the drawings.

[0026] (First Embodiment) A first embodiment of the double-row angular contact ball bearing of the present invention will be described with reference to Figure 1. Figure 1 is a longitudinal cross-sectional view of the bearing. As shown in Figure 1, the double-row angular contact ball bearing 1 comprises an outer ring 2 having an outer ring raceway surface 2a on its inner circumference, an inner ring 3 having an inner ring raceway surface 3a on its outer circumference, and a plurality of rolling elements 4 arranged between the outer ring raceway surface 2a and the inner ring raceway surface 3a. Here, the outer ring raceway surface 2a and the inner ring raceway surface 3a are each concave grooves extending in the circumferential direction. The outer ring 2 has a plurality of axially adjacent (two rows in Figure 1) outer ring raceway surfaces 2a, and the inner ring 3 has a plurality of axially adjacent (two rows in Figure 1) inner ring raceway surfaces 3a. The outer ring 2 and the inner ring 3 are each annular, and the inner ring 3 is arranged concentrically with the outer ring 2 so as to be able to rotate relative to it.

[0027] In this configuration, both the outer ring 2 and the inner ring 3 are separable raceway rings divided into two axial sections, with each separated raceway ring having one row of raceway surfaces. The double-row angular contact ball bearing 1 has two rows of raceways formed by the opposing raceway surfaces 2a of the outer ring and 3a of the inner ring. Multiple rolling elements 4 are arranged in each raceway, and the rolling elements 4 are rotatably held by a cage 5. The radius of curvature of each raceway surface 2a, 3a is dimensioned to be slightly larger than the radius of curvature of the rolling elements 4.

[0028] The double-row angular contact ball bearing 1 of the first embodiment is composed of single-row angular contact ball bearings arranged back-to-back. Each angular contact ball bearing has an inner ring and an outer ring, and the rolling elements are in contact with each other at a predetermined angle α (contact angle) with respect to the radial centerline, and can withstand radial loads and unidirectional axial loads. In Figure 1, the direction of the contact angle α of the rolling elements 4 in each raceway is different from that of the other, so that it can withstand bidirectional axial loads. In the present invention, the contact angle α is not particularly limited, but is preferably 20 to 40°, and more preferably 25 to 35°.

[0029] Furthermore, the outer ring 2 has shoulders 2b on the load side of its inner circumference where it makes contact with the rolling elements 4. In the double-row angular contact ball bearing 1, shoulders 2b are the inner shoulders, and shoulders 2c are the outer shoulders. In Figure 1, the shoulder height of shoulder 2c is smaller than that of shoulder 2b. The inner ring 3 also has shoulders on both axial sides of each inner ring raceway surface 3a on its outer circumference. In the double-row angular contact ball bearing 1, the inner ring 3 has an inner shoulder 3b and an outer shoulder 3c. The shoulder heights of shoulders 3b and 3c are the same.

[0030] In a double-row angular contact ball bearing 1, the outer ring may have multiple outer ring raceway surfaces on its inner circumference, and may have three or more rows. Similarly, the inner ring may also have three or more inner ring raceway surfaces. The number of outer ring raceway surfaces and inner ring raceway surfaces are equal. For example, three single-row angular contact ball bearings may be combined in parallel in the axial direction.

[0031] Due to the above configuration, the double-row angular contact ball bearing 1 can be assembled from the side along with the divided raceways (outer ring 2 and inner ring 3 in Figure 1) during bearing assembly. As a result, the number of rolling elements 4 arranged in the raceways can be increased, and the rated load can be increased.

[0032] (Second Embodiment) A second embodiment of the double-row angular contact ball bearing of the present invention will be described with reference to Figure 2. Components identical to those described in the first embodiment with reference to Figure 1 are denoted by the same reference numerals, and detailed descriptions are omitted.

[0033] As shown in Figure 2, in the double-row angular contact ball bearing 1', the inner ring 3 is a separable raceway ring divided into two axial sections, with each separated raceway ring having one row of raceway surfaces. The outer ring 2' is a non-separable (integrated) raceway ring, a single raceway ring that is not divided axially. The outer ring 2' also has two rows of raceway surfaces 2a' on its inner circumference, with a shoulder portion 2b' between these raceway surfaces.

[0034] In the configuration having both separable and non-separable raceways, as shown in the second embodiment, assembly is superior compared to the configuration in the first embodiment where both the inner and outer raceways are separable. Furthermore, since non-separable raceways have a smaller width, space can be saved.

[0035] In addition, in the double-row angular contact ball bearing of the present invention, the arrangement of the raceways is not limited to a back-to-back arrangement; a front-to-back arrangement may also be used when the outer ring is separate and the inner ring is integrated.

[0036] Next, with reference to Figure 3, the dimensional relationships of each component in the double-row angular contact ball bearing will be explained. Figure 3 is a partial cross-sectional view of the double-row angular contact ball bearing of the second embodiment shown in Figure 2. Note that the dimensional relationships described below can also be applied to other embodiments (such as the first embodiment).

[0037] In a double-row angular contact ball bearing 1', it is preferable that the height (shoulder height) hD of the shoulder portion 2b' of the outer ring 2' satisfies the following formula (1). 0.15×(Dα-dp)≦hD≦0.35×(Dα-dp)···(1) Dα: Diameter of the contact point between the outer ring 2' and the rolling element 4. dp: Pitch diameter of rolling element 4

[0038] Here, the shoulder height hD of the outer ring 2' refers to the height difference between the shoulder portion 2b' of the outer ring 2' and the deepest part of the outer ring raceway surface 2a'. Note that if the height difference differs between the inner shoulder portion, which is located between the two rows of outer ring raceway surfaces 2a', 2a' of the outer ring 2', and the outer shoulder portion, which is located axially outward from the two rows of outer ring raceway surfaces 2a', 2a', the shoulder height hD refers to the height difference of the higher shoulder portion. Generally, when the height difference differs between the inner and outer shoulder portions, the shoulder on the load-bearing side is often higher. The contact point diameter Dα refers to the diameter of the circle formed by the contact point between the outer ring 2' and the rolling element 4. The pitch diameter dp refers to the diameter of the circle traced by the center of the rolling element 4 when the rolling element 4 rotates on the raceway.

[0039] When the shoulder height hD of the outer ring 2' is 0.15 times or more the difference between the contact point diameter Dα and the pitch diameter dp (Dα-dp), shoulder overloading of the rolling elements becomes less likely, and axial loads and moment loads can be stably supported more easily. Furthermore, when the shoulder height hD of the outer ring 2' is 0.35 times or less the above (Dα-dp) value, it becomes easier to secure sufficient space for placing the cage. As a result, it becomes unnecessary to thin the cage, and it becomes easier to ensure the strength of the cage. It is preferable that the shoulder height hD is 0.20 times or more and 0.30 times or less the above (Dα-dp) value.

[0040] Furthermore, in a double-row angular contact ball bearing 1', it is preferable that the height (shoulder height) hd of the shoulder portion 3b of the inner ring 3 satisfies the following formula (2). 0.15×(dp-dα)≦hd≦0.35×(dp-dα)···(2) dα: Diameter of the contact point between the rolling element 4 and the inner ring 3. dp: Pitch diameter of rolling element 4

[0041] Here, the shoulder height hd of the inner ring 3 refers to the height difference between the shoulder portion 3c of the inner ring 3 (in this embodiment, the shoulder portion 3b and the shoulder portion 3c have the same shoulder height, so it may also be the shoulder portion 3b) and the deepest part of the inner ring raceway surface 3a. If the height difference differs between the inner shoulder portion 3b, which is provided between the two rows of inner ring raceway surfaces 3a, 3a of the inner ring 3, and the outer shoulder portion 3c, which is provided axially outward from the two rows of inner ring raceway surfaces 3a, 3a, then the shoulder height hd refers to the height difference of the shoulder portion on the load-bearing side. As mentioned above, generally, when the height difference differs between the inner shoulder portion and the outer shoulder portion, the shoulder portion on the load-bearing side is often higher. Also, the contact point diameter dα refers to the diameter of the circle formed by the contact point between the inner ring 3 and the rolling element 4.

[0042] When the shoulder height hd of the inner ring 3 is 0.15 times or more the difference between the contact point diameter dα and the pitch diameter dp (dp-dα), shoulder overloading of the rolling elements becomes less likely. Furthermore, when the shoulder height hd of the inner ring 3 is 0.35 times or less the above difference (dp-dα), it becomes easier to secure sufficient space for positioning the cage. It is more preferable that the shoulder height hd is 0.20 times or more and 0.30 times or less the above value of (dp-dα).

[0043] The above equations (1) and (2) were discovered as a result of various studies by changing the contact angle α and the diameter Db of the rolling element 4, etc., as conditions that make it difficult for the rolling element shoulders to occur and secure a large space for arranging the cage. Generally, the shoulder heights hD and hd are sometimes set as a multiplier to the diameter Db of the rolling element, but by using the above equations (1) and (2), it becomes easier to evaluate from the perspectives of both the shoulder overhang of the rolling element 4 and the securing of space inside the bearing.

[0044] Furthermore, in a double-row angular contact ball bearing 1', it is preferable that the diameter Db of the rolling element 4 and the bearing width (axial width of the bearing) Wb satisfy the relationship shown in equation (3) below. 1.1 ≤ Wb / (Db × 2) ≤ 1.7 ···(3)

[0045] Here, the diameter Db of the rolling element 4 refers to the nominal diameter of the rolling element. The bearing width Wb refers to the axial length of the raceway ring (the longer one if it differs between the inner ring 3 and the outer ring 2').

[0046] When Wb / (Db×2) is 1.1 or greater, there is no need to reduce the diameter Db of the rolling element 4, making it easier to ensure the strength of the shoulder and the rated load. Furthermore, when Wb / (Db×2) is 1.7 or less, it offers superior compactness. In addition, Wb / (Db×2) of 1.4 or greater and 1.7 or less is more preferable.

[0047] Furthermore, in the angular contact ball bearing 1', it is preferable that the filling ratio γ of the rolling elements 4 arranged in one row of raceways is 0.65 to 0.90. The filling ratio γ is expressed by the following formula (4). γ = (Db × Z) / (dp × π) ... (4)

[0048] When the filling ratio γ is 0.65 or higher, it becomes easier to achieve a higher rated load than with non-separable double-row angular contact ball bearings for both the inner and outer rings. Also, when the filling ratio is 0.90 or lower, the column width between the cage pockets does not become too small, making it easier to ensure the strength of the cage. A filling ratio γ of 0.70 to 0.90 is more preferable, and 0.80 to 0.90 is even more preferable.

[0049] In the double-row angular contact ball bearing of the present invention, it is preferable that at least one of the above-described formulas (1) to (4) is satisfied, and it is particularly preferable that all of them are satisfied.

[0050] (Third embodiment) A third embodiment of the double-row angular contact ball bearing of the present invention will be described (not shown). The double-row angular contact ball bearing of the present invention does not have to be configured such that at least one of the outer ring and inner ring raceways is divided in the axial direction, as described in the first and second embodiments. Specifically, it may be a double-row angular contact ball bearing in which both the outer ring and inner ring are non-separable raceways. Detailed descriptions of configurations identical to those of the first and second embodiments will be omitted.

[0051] The double-row angular contact ball bearing of the third embodiment has non-separable raceways for both the outer ring and the inner ring. In this double-row angular contact ball bearing, shoulders are formed on the inner circumference of the outer ring and the outer circumference of the inner ring, respectively, with the height hD of the shoulder of the outer ring satisfying the following formula (5), and the height hd of the shoulder of the inner ring satisfying the following formula (6). 0.15×(Dα-dp)≦hD≦0.35×(Dα-dp)···(5) 0.15×(dp-dα)≦hd≦0.35×(dp-dα)···(6)

[0052] In a double-row angular contact ball bearing, if both the outer and inner rings are non-separable raceways, it is more preferable, from the viewpoint of ball insertion, that the height hD of the shoulder of the outer ring satisfies the following equation (7) and the height hd of the shoulder of the inner ring satisfies the following equation (8). 0.15×(Dα-dp)≦hD≦0.31×(Dα-dp)···(7) 0.15×(dp-dα)≦hd≦0.31×(dp-dα)···(8)

[0053] As a result, the double-row angular contact ball bearing of the third embodiment is less prone to the shoulders of the rolling elements riding up, has excellent axial load capacity and moment load capacity, and allows for sufficient space to arrange the cage.

[0054] The double-row angular contact ball bearing of the present invention is used in pumps. As an example of a configuration in which it is applied to a hydrogen circulation pump, Figure 4 shows a cross-sectional view of the hydrogen circulation pump. The hydrogen circulation pump 11 has a motor housing 12, a pump housing 13, rotating shafts 14 and 15, a motor stator 16, a motor rotor 17, gears 18 and 19, rotors 20 and 21, and rolling bearings 22, 23, 24, 25, 26, and 27. Here, rolling bearings 25 and 27 are the double-row angular contact ball bearings of the present invention, and rolling bearings 22, 23, 24, and 26 are deep groove ball bearings.

[0055] The motor housing 12 is attached to the pump housing 13. One end of the rotating shaft 14 is located inside the motor housing 12, and the other end of the rotating shaft 14 is located inside the pump housing 13. The one end and the other end of the rotating shaft 14 are rotatably supported by a rolling bearing 22 located inside the motor housing 12 and a rolling bearing 23 located inside the pump housing 13, respectively. The rotating shaft 14 is also rotatably supported between the one end and the other end by rolling bearings 24 and 25 located inside the pump housing 13.

[0056] The rotating shaft 15 is located within the pump housing 13. One end of the rotating shaft 15 is rotatably supported by a rolling bearing 26 located within the pump housing 13. The rotating shaft 15 is also rotatably supported at a position away from the other end by a rolling bearing 27 located within the pump housing 13.

[0057] The motor stator 16 is located inside the motor housing 12. The motor rotor 17 is mounted on the rotating shaft 14 so as to face the motor stator 16. The motor stator 16 and motor rotor 17 rotate the rotating shaft 14. Gears 18 and 19 are mounted on the rotating shaft 14 and the rotating shaft 15, respectively. The rotation of the rotating shaft 14 is transmitted to the rotating shaft 15 by gears 18 and 19. Gear 18 is located between rolling bearings 24 and 25, and gear 19 is located between rolling bearings 26 and 27.

[0058] A pump chamber 13a is formed inside the pump housing 13. Rotors 20 and 21 are arranged inside the pump chamber 13a. Rotors 20 and 21 are attached to the rotating shafts 14 and 15, respectively. As rotor 20 rotates with the rotation of the rotating shaft 14, and rotor 21 rotates with the rotation of the rotating shaft 15, hydrogen is drawn into the pump chamber 13a and discharged from the pump chamber 13a.

[0059] The rolling bearings 25 and 27 according to the present invention rotatably support rotating shafts 14 and 15, to which rotors 20 and 21, which are fitted to mating rotors, are connected on one end, and gears 18 and 19, which are fitted to mating gears, are connected on the other end. These shafts are susceptible to axial loads and moment loads. In the configuration shown in Figure 4, in particular, the rolling bearing 27, which supports the rotating shaft 15 connected to the driven gear 19 and the driven rotor 21, has a free end on the rotor 21 side of the rotating shaft 15 and is a cantilever support structure, making it more susceptible to loads. In this configuration, by employing the double-row angular contact ball bearings of the present invention, it is believed that the rotating shaft of the hydrogen circulation pump can rotate stably without axial runout.

[0060] Furthermore, the double-row angular contact ball bearing of the present invention can be used not only in hydrogen circulation pumps but also in other pumps. [Examples]

[0061] The present invention will be specifically described by way of examples, but it is not limited by these examples in any way.

[0062] Five types of bearings (Example A) with a separable inner ring and an integral outer ring and different contact angles were examined as follows.

[0063] <Examination of shoulder heights hd and hD> In Example A where the shoulder height hD was 0.15 to 0.35 times (specifically, 0.15 times, 0.17 times, 0.30 times, 0.32 times, 0.35 times) the difference (Dα - dp) between the diameter Dα of the contact point between the rolling element and the outer ring and the pitch diameter dp of the rolling element, and the shoulder height hd was 0.15 to 0.35 times (specifically, 0.15 times, 0.17 times, 0.30 times, 0.32 times, 0.35 times) the difference (dp - dα) between the pitch diameter dp of the rolling element and the diameter dα of the contact point between the rolling element and the inner ring, it was found that riding up of the rolling element was less likely to occur and it was easy to secure sufficient space for arranging the cage.

[0064] Five types of bearings (Example B) with a separable inner ring and an integral outer ring, and three types of double-row angular ball bearings (Reference Examples) with non-separable inner and outer rings were examined as follows.

[0065] <Examination of Wb / (Db×2)> For Example B and the Reference Examples, Wb / (Db×2) was calculated. As a result, Wb / (Db×2) for Example B was 1.407, 1.575, 1.599, 1.599, 1.642 respectively. Also, Wb / (Db×2) for the Reference Examples was 1.167, 1.293, 1.501 respectively.

[0066] <Examination of filling ratio γ of rolling elements> Next, for Example B and the Reference Examples described above, the filling ratio γ was calculated. As a result, the filling ratio γ for Example B was 0.81, 0.82, 0.83, 0.84, 0.85 respectively. In contrast, the filling ratio γ for the Reference Examples was 0.53, 0.57, 0.60 respectively.

Industrial Applicability

[0067] The double-row angular contact ball bearing of the present invention has excellent axial load capacity and moment load capacity, and also allows for sufficient space to arrange the cage, or has good assembly characteristics, so it can be used in pumps, and is particularly suitable for hydrogen circulation pumps. [Explanation of Symbols]

[0068] 1, 1' Double row angular contact ball bearing 2, 2' outer ring 2a, 2a' Outer ring raceway surface 2b, 2c Shoulder 3. Inner Ring 3a Inner ring raceway surface 3b, 3c Shoulder 4 Rolling elements 5 Cage 11 Hydrogen circulation pump 12 Motor Housing 13 Pump Housing 14, 15 Rotation axis 16 Motor Stator 17 Motor Rotor 18, 19 gears 20, 21 rotors 22, 23, 24, 25, 26, 27 Rolling bearings

Claims

1. A double-row angular contact ball bearing used in a hydrogen circulation pump, comprising an outer ring having an outer ring raceway on its inner circumference, an inner ring having an inner ring raceway on its outer circumference, and a plurality of rolling elements arranged between the outer ring raceway and the inner ring raceway, each having multiple outer ring raceway surfaces and inner ring raceway surfaces, In the aforementioned double-row angular contact ball bearing, at least one of the raceways of the outer ring and the inner ring is divided in the axial direction. Shoulders are formed on the inner circumference of the outer ring and the outer circumference of the inner ring, respectively, and the shoulders of the inner ring are of the same height on the inner side and the outer side. A double-row angular contact ball bearing characterized in that the height hD of the shoulder portion of the outer ring satisfies the following formula (1), and the height hd of the shoulder portion of the inner ring satisfies the following formula (2). 0.15×(Dα-dp)≦hD≦0.35×(Dα-dp)...(1) 0.15×(dp-dα)≦hd≦0.35×(dp-dα)...(2) Dα: Diameter of the contact point between the outer ring and the rolling element. dα: Diameter of the contact point between the inner ring and the rolling element. dp: Pitch diameter of the rolling element

2. The double-row angular contact ball bearing according to claim 1, characterized in that one of the raceways of the outer ring and the inner ring is a separable raceway that is divided in the axial direction, and the other raceway is an integrated raceway having multiple raceway surfaces.

3. The double-row angular contact ball bearing according to claim 1 or 2, characterized in that the double-row angular contact ball bearing has two rows in which the outer ring raceway surface and the inner ring raceway surface face each other, and the direction of the contact angle of the rolling elements in each row is different from that of the other.

4. The double-row angular contact ball bearing according to claim 3, characterized in that the arrangement is a back-to-back combination.

5. The double-row angular contact ball bearing according to claim 1 or 2, characterized in that the diameter Db of the rolling elements and the axial width Wb of the double-row angular contact ball bearing satisfy the following equation (3). 1.1 ≤ Wb / (Db × 2) ≤ 1.7 ... (3)

6. The double-row angular contact ball bearing according to claim 1 or 2, characterized in that the filling ratio γ of the rolling elements arranged in one row of raceways, as represented by the following formula (4), is 0.65 to 0.

90. γ=(Db×Z) / (dp×π)...(4) Db: Diameter of the rolling element Z: Number of rolling elements dp: Pitch diameter of the rolling element

7. The double-row angular contact ball bearing according to claim 1 or 2 is characterized in that it is a bearing that rotatably supports a rotating shaft to which a rotor that is fitted with a mating rotor is connected on one end and a gear that is fitted with a mating gear is connected on the other end.

8. A double-row angular contact ball bearing used in a hydrogen circulation pump, comprising an outer ring having an outer ring raceway on its inner circumference, an inner ring having an inner ring raceway on its outer circumference, and a plurality of rolling elements arranged between the outer ring raceway and the inner ring raceway, each having multiple outer ring raceway surfaces and inner ring raceway surfaces, Shoulders are formed on the inner circumference of the outer ring and the outer circumference of the inner ring, respectively, and the shoulders of the inner ring are of the same height on the inner side and the outer side. A double-row angular contact ball bearing characterized in that the height hD of the shoulder portion of the outer ring satisfies the following formula (5), and the height hd of the shoulder portion of the inner ring satisfies the following formula (6). 0.15×(Dα-dp)≦hD≦0.35×(Dα-dp) (5) 0.15×(dp-dα)≦hd≦0.35×(dp-dα)...(6) Dα: Diameter of the contact point between the outer ring and the rolling element. dα: Diameter of the contact point between the inner ring and the rolling element. dp: Pitch diameter of the rolling element

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