Rolling bearing

Abstract

In a rolling bearing (1) having a retainer (5) having an annular guided surface (Sb) guided by an annular guide surface (Sa) of the outer ring (3) during bearing operation, and each pocket (6) being a circular hole with a constant opening size (W) along the radial direction, a large pocket (6A) and a small pocket (6B) are provided as pockets (6). When the design value of the radial clearance (Ga2) between the guide surface (Sa) and the guided surface (Sb) is set to δ, the size of the radial clearance (Ga2) when the bearing is running is set to δ0, and the size of the circumferential clearance (Gb1, Gb2) between the large pocket (6A) and the small pocket (6B) formed in the neutral state of the retainer (5) and the ball (4) is set to ε1 and ε2 respectively, the inequality ε2<δ0<ε1 and the inequality 0mm<(δ-δ0)<0.5mm are satisfied, and the movable area (10) of the retainer is a non-circular shape with a circle whose diameter is the size of the radial clearance (Ga2) when the bearing is running as δ0 as the circumcircle.

Description

Technical Field

[0001] This invention relates to rolling bearings. Background Technology

[0002] Figure 9A A schematic cross-sectional view of a rolling bearing 100 is shown. The rolling bearing 100 shown in the figure has: a pair of raceways (inner ring 101 and outer ring 102) that are radially opposed and rotate about a central axis via a plurality of rolling elements (here, balls) 103; and an annular retainer 104 that holds the plurality of rolling elements 103 at circumferential intervals. The retainer 104 is assembled between the raceways in a no-load state, where gravity, rotational forces, etc., do not act on the rolling bearing, such that radial clearances 111 and 112 are formed between the outer circumferential surface 101a of the inner ring 101 and the inner circumferential surface 102a of the outer ring 102, respectively, and a circumferential clearance 113 is formed between the rolling elements 103 housed in pockets 105 formed by circular holes with a radially constant opening size. The aforementioned radial clearances 111 and 112 are also referred to as "guide clearances," and the aforementioned circumferential clearance 113 is also referred to as "pocket clearance."

[0003] Rolling bearings can be broadly classified into raceway-guided type and rolling element-guided type based on the guiding method of the cage 104. Raceway-guided type can be further broadly classified into outer ring-guided type and inner ring-guided type. In a broad sense, outer ring-guided type refers to the type with the smaller radial clearance 112 of the two radial clearances 111 and 112 mentioned above. Among outer ring-guided bearings, there are types where the circumferential clearance 113 between the pocket forming surface 105a of the cage 104 in its neutral position (cage 104 in an unloaded state) and the rolling element 103 is larger or smaller than the radial clearance 112. Figure 9A , Figure 9B The former was shown. Figure 10A , Figure 10B The latter is shown. Although the illustration is omitted, the inner ring guide type is, in a broad sense, the type where the radial clearance 111 is smaller of the two radial clearances 111 and 112 mentioned above. Additionally, although the illustration is also omitted, the rolling element guide type is the type where the opening size of the pocket 105 is not constant along the radial direction, and the radial clearance formed between the pocket forming surface 105a and the rolling element 103 is smaller than the two radial clearances 111 and 112.

[0004] However, when the rolling bearing 100, in which the inner ring 101 and the outer ring 102 rotate relative to each other, is operating, an abnormally high-speed oscillating rotation (a self-excited vibration that vibrates at several times the rotational frequency of the cage) sometimes occurs in the cage 104, also known as high-speed whirl. This high-speed whirl phenomenon occurs even when the value of dn, which is the product of the inner diameter [mm] and the rotational speed [rpm] of the rolling bearing 100, is approximately 1,500,000 or less (dn≤1,500,000). When high-speed whirl occurs, it can cause abnormal noise, vibration, increased torque, torque fluctuation, and heat generation. The high-speed whirl phenomenon occurs, for example, due to friction generated by the contact between the guide surface of the raceway ring and the guided surface of the cage 104, and friction generated by the contact between the pocket forming surface 105a of the cage 104 and the rolling element 103.

[0005] by Figure 9A and Figure 9B Taking the outer ring guided type rolling bearing 100 as an example, the mechanism of the high-speed rapid rotation phenomenon caused by the frictional force generated by the contact between the guiding surface of the raceway ring and the guided surface of the retainer 104 will be explained. In this case, the guiding surface of the raceway ring is the inner circumferential surface 102a of the outer ring 102, and the guided surface of the retainer 104 is the outer circumferential surface of the retainer 104. In addition, although the figure is omitted, in the inner ring guided type rolling bearing, "guiding surface of the raceway ring" = "outer circumferential surface of the inner ring", and "guided surface of the retainer" = "inner circumferential surface of the retainer".

[0006] First, such as Figure 9A As shown, when the retainer 104 is displaced relative to the axis O towards point 0 (12 o'clock), the retainer 104 contacts the inner circumferential surface 102a of the outer ring 102 at the point 0 position. At this time, if the inner ring 101 rotates clockwise, a frictional force F is applied to the retainer 104 in the direction that causes it to displace towards point 9. If the retainer 104, displaced by this frictional force F, contacts the inner circumferential surface 102a of the outer ring 102 at the point 9, then as... Figure 9B As shown, a frictional force F is generated in the retainer 104, causing it to displace in the direction of 6 o'clock. Moreover, as the inner ring 101 continues to rotate and the above phenomenon (displacement of the retainer 104 and contact with the inner circumferential surface 102a of the outer ring 102) repeats, the retainer 104 oscillates and rotates at high speed in the direction opposite to the rotation direction of the inner ring 101.

[0007] In addition, according to Figure 10A and Figure 10B This explains the mechanism of the high-speed rapid rotation phenomenon caused by the frictional force generated from the contact between the pocket forming surface 105a of the retainer 104 and the rolling element 103. For example... Figure 10AAs shown, when the retainer 104 displaces relative to the axis O towards the 0 point (12 o'clock), the rolling element 103 positioned at the 3 o'clock and 9 o'clock positions contacts the pocket forming surface 105a at the 6 o'clock position. At this time, if the inner ring 101 wishes to rotate clockwise, a frictional force F is generated in the retainer 104, causing it to displace towards the 3 o'clock position. When the retainer 104 is displaced by this frictional force F, as... Figure 10B As shown, the rolling element 103, positioned at the 0 and 6 o'clock positions, contacts the pocket forming surface 105a at the 9 o'clock position. This generates a frictional force F that displaces the retainer 105 towards the 6 o'clock position. Subsequently, by repeating this phenomenon, the retainer 104 oscillates at high speed in the same direction as the rotation of the inner ring 101.

[0008] In order to prevent abnormal noises and vibrations caused by the high-speed rapid rotation of the retainer mentioned above, for example, in the rolling bearing described in Patent Document 1 below, a specified imbalance is intentionally given to the retainer so that the retainer rotates in an eccentric state (so that a part of the retainer is always in contact with the raceway).

[0009] Existing technical documents

[0010] Patent documents

[0011] Patent Document 1: Japanese Patent Application Publication No. 2011-196513 Summary of the Invention

[0012] The problem that the invention aims to solve

[0013] However, to achieve the technical means described in Patent Document 1, firstly, the retainer needs to be formed into a non-point-symmetrical shape, thus requiring considerable effort to machine the retainer with high precision. Furthermore, to ensure the required durability of the rolling bearing, wear at the constant contact point between the retainer and the raceway needs to be suppressed; therefore, measures such as precision grinding of the opposing surfaces of the raceway and retainer are required to achieve extremely high precision. Therefore, achieving the technical means of Patent Document 1 results in increased costs.

[0014] In view of the above actual situation, the purpose of the present invention is to realize a rolling bearing that can prevent the occurrence of high-speed rapid rotation and the resulting abnormal noise, vibration, etc. at low cost.

[0015] Methods for solving problems

[0016] The present invention, proposed to achieve the aforementioned objective, is a rolling bearing comprising: a pair of raceways arranged radially opposite each other and rotating relative to each other via a plurality of rolling elements; and a retainer, which is annular in shape and has a plurality of pockets spaced apart circumferentially to accommodate the rolling elements, wherein one of the raceways has an annular guide surface, and the retainer has an annular guided surface radially opposite the guide surface; each pocket is formed by a circular hole with a constant opening size along the radial direction; characterized in that at least one of the plurality of pockets is formed as a large pocket, and the remaining pockets are formed as small pockets with opening sizes smaller than the large pocket; and the design value of the radial clearance formed between the guide surface and the guided surface is set to... When the radial clearance during bearing operation is set to δ0, and the circumferential clearance between the large pocket forming surface and the small pocket forming surface of the retainer in the neutral state and the rolling element is set to ε1 and ε2 respectively, the inequalities ε2<δ0<ε1 and 0mm<(δ-δ0)<0.5mm are satisfied. Furthermore, when the area surrounded by the line connecting the outer edge of the scatter plot is defined as the movable area of ​​the retainer, the movable area of ​​the retainer has a non-circular shape with a circle whose diameter is the aforementioned radial clearance δ0 during bearing operation as the circumcircle. This scatter plot is obtained by drawing numerous positions on a two-dimensional coordinate system where the retainer can exist without contacting a pair of track rings and rolling elements.

[0017] Furthermore, the "neutral state" mentioned in this invention refers to a state in which the center of the circular hole of the retainer forming the pocket is aligned with the center of the rolling element and the two are not in contact with each other.

[0018] First, as referenced Figure 9A , Figure 9B and Figure 10A , Figure 10B As explained, when a bearing with a pair of track rings rotating relative to each other is in operation, the frictional force generated by the contact between the retainer and the track rings and the frictional force generated by the contact between the retainer and the rolling elements are in opposite directions. Therefore, if the two frictional forces can be generated in a balanced manner when the bearing is in operation, it is considered that both can be reduced or offset by the frictional force of the other, which is the cause of the high-speed spinning phenomenon.

[0019] Therefore, in the rolling bearing of the present invention, at least one of the pockets formed by a plurality of circular holes provided in the retainer is formed as a large pocket, and the remaining pockets are formed as small pockets with an opening size smaller than the large pocket. Furthermore, during bearing operation, the radial clearance ("guide clearance") δ0 formed between the guide surface of the raceway and the guided surface of the retainer, and the circumferential clearances ("pocket clearance") ε1 and ε2 formed between the large pocket forming surface (the surface forming the large pocket) and the small pocket forming surface (the surface forming the small pocket) of the retainer in its neutral state and the rolling element, respectively, satisfy the inequality ε2 < δ0 < ε1. With this structure, the contact between the rolling element and the small pocket of the retainer and the contact between the guide surface of the raceway and the guided surface of the retainer can be switched by the radial displacement of the retainer during bearing operation. Therefore, one of the two frictional forces generated during bearing operation can be reduced or offset by the frictional force of the other.

[0020] Normally, the guide clearance δ0 of a bearing decreases relative to the design value δ due to the expansion of the retainer and other components caused by heat and centrifugal force during operation. This reduction (δ-δ0) is at most about 0.5 mm under conditions of high-speed rapid rotation, satisfying the inequality 0 mm < (δ-δ0) < 0.5 mm.

[0021] Even when the above two inequalities hold, depending on the arrangement of the pockets and the relationship between the radial clearance, it is possible that only the small pocket of the retainer contacts the rolling element, while the guiding surface of the raceway ring cannot contact the guided surface of the retainer. In this case, the desired rapid rotation suppression effect cannot be achieved. Therefore, in this invention, the design values ​​of the pocket clearance of the small pocket, the guiding clearance, and the arrangement of the large and small pockets are studied in a way that the area enclosed by the line connecting the outer edge of the scatter plot is defined as the "retainer movable area," and this movable area has a non-circular shape with a circle whose circumscribed circle is a circle with a diameter of δ0, the size of the radial clearance during bearing operation. This scatter plot is obtained by plotting numerous positions on a two-dimensional coordinate system where the retainer can exist without contacting a pair of raceways and rolling elements. Thus, the situation where the rolling element contacts the retainer (small pocket) and the situation where the guiding surface of the raceway ring contacts the guided surface of the retainer can be appropriately switched by the displacement of the retainer.

[0022] Furthermore, the rolling bearing of the present invention, by providing a pocket in the retainer consisting of two circular holes of different opening sizes, can prevent high-speed rapid rotation, which can be easily and cost-effectively implemented compared to the method described in Patent Document 1. Additionally, in the structure of the present invention, the guided surface of the retainer is not always in contact with the guiding surface of the raceway. Compared to the rolling bearing described in Patent Document 1, the contact frequency between the guiding surface and the guided surface can be suppressed, thus eliminating the need to machine the guiding surface and the guided surface to extremely high precision.

[0023] The contact portion of the retainer's movable area that contacts the circumscribed circle is an arc shape with a length in the circumferential direction of the circumscribed circle, and multiple such arc-shaped contact portions are provided at intervals in the circumferential direction of the circumscribed circle. It is particularly preferable to provide three or more such arc-shaped contact portions at equal intervals in the circumferential direction of the circumscribed circle. This allows for precise switching of the contact objects of the retainer at regular intervals, appropriately reducing or offsetting one of the two frictional forces generated during bearing operation through the frictional force of the other.

[0024] In the above structure, as a configuration of multiple pockets (large pockets and small pockets), for example, when the retainer is divided into 6 equal regions in the circumferential direction, large pockets are arranged clockwise in the first, third and fifth regions, and small pockets are arranged in the second, fourth and sixth regions.

[0025] In the above structure, the guide surface can be the inner circumferential surface of the outer ring of a pair of track rings located radially outside the retainer, or it can be the outer circumferential surface of the inner ring of a pair of track rings located radially inside the retainer.

[0026] Invention Effects

[0027] According to the present invention, a rolling bearing that can prevent high-speed rapid rotation and the resulting abnormal noise, vibration, etc., can be realized at low cost. Attached Figure Description

[0028] Figure 1 This is a partial schematic top view of a rolling bearing according to an embodiment of the present invention.

[0029] Figure 2 yes Figure 1 Sectional view along line A1-A1.

[0030] Figure 3 yes Figure 1 Sectional view along line A2-A2.

[0031] Figure 4 It is assembled in Figure 1 A schematic top view of the retainer of the rolling bearing shown.

[0032] Figure 5 It shows that it has adopted Figure 4 A diagram showing the movable area of ​​the retainer in a rolling bearing.

[0033] Figure 6 This is a schematic diagram used to illustrate the method for determining the movable area of ​​the retainer.

[0034] Figure 7 This is a diagram showing the movable area of ​​the retainer in a rolling bearing employing a modified retainer.

[0035] Figure 8 The diagram shows the movable area of ​​the retainer of a rolling bearing that does not have the structure of the present invention.

[0036] Figure 9A This is a schematic cross-sectional view of an outer ring-guided rolling bearing, where the radial clearance between the inner diameter of the outer ring and the outer diameter of the cage is smaller than the circumferential clearance between the pocket forming surface and the rolling element.

[0037] Figure 9B It is shown Figure 9A A cross-sectional view of the retainer of the rolling bearing shown, in the state of radial displacement.

[0038] Figure 10A This is a schematic cross-sectional view of an outer ring-guided rolling bearing, where the radial clearance between the inner diameter of the outer ring and the outer diameter of the cage is larger than the circumferential clearance between the pocket forming surface and the rolling element.

[0039] Figure 10B It is shown Figure 10A A cross-sectional view of the retainer of the rolling bearing shown, in the state of radial displacement. Detailed Implementation

[0040] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Furthermore, unless otherwise specified, the terms "axial," "radial," and "circumferential," used below to indicate directionality, refer to the directions of the present invention. Figure 1 The rolling bearing 1 shown has its axis O parallel to the direction of rotation, the radial direction of the circle centered on axis O, and the circumferential direction of the circle centered on axis O. Figure 2 and Figure 3 In the diagram, arrows X, Y, and Z represent "axial", "radial", and "circumferential" directions, respectively.

[0041] Figure 1 This is a partial schematic top view of the rolling bearing 1 according to an embodiment of the present invention. More specifically, it is a partial schematic top view of the rolling bearing 1 in a no-load state without the action of gravity, rotational force, etc. Figure 2 yes Figure 1Sectional view along line A1-A1, Figure 3 yes Figure 1 Sectional view along line A2-A2. Figure 1 The rolling bearing 1 shown is a so-called angular contact ball bearing, which has a pair of raceways (inner ring 2 and outer ring 3) formed of a high-rigidity metal material such as bearing steel (high carbon chromium bearing steel), a plurality of balls 4 that are rolled freely between the inner ring 2 and the outer ring 3, and an annular retainer 5 that holds the plurality of balls 4 at circumferential intervals. The balls 4 are in contact with the arc-shaped inner raceway surface 2b formed on the outer peripheral surface 2a of the inner ring 2 and the arc-shaped outer raceway surface 3b formed on the inner peripheral surface 3a of the outer ring 3 at a contact angle α.

[0042] The retainer 5 forms multiple pockets 6 to house the balls 4 one by one. In the example shown, the retainer 5 has a total of 24 pockets 6 spaced at 15° intervals. Figure 2 and Figure 3 As shown, each pocket 6 is formed by a circular hole with a constant opening size (pocket diameter) W along the radial direction, and the pocket forming surface 7 of the retainer 5 forming the pocket 6 is formed as a cylindrical surface with a constant diameter.

[0043] The retainer 5 is a resin retainer made of resin materials such as PA66 resin and phenolic resin (especially phenolic resin for fabric substrates). However, as long as each pocket 6 is made of a circular hole as described above, a known retainer other than a resin retainer can also be used as the retainer 5, such as a so-called cut retainer obtained by cutting metal material into a specified shape, or a stamped retainer obtained by combining a pair of retainer raw materials that have been stamped (cut) into a specified annular shape.

[0044] like Figure 2 and Figure 3 As shown, in a no-load state where gravity, rotational force, etc., do not act on the rolling bearing 1, the retainer 5 is in a neutral state (not in contact with the balls 4, inner ring 2, and outer ring 3) forming radial clearances with the inner ring 2 and outer ring 3, and forming a circumferential clearance with the balls 4 housed in the pocket 6. Therefore, when the retainer 5 is in the neutral state, a first radial clearance Ga1 is formed between the outer circumferential surface 2a of the inner ring 2 and the inner circumferential surface 5a of the retainer 5, a second radial clearance Ga2 is formed between the inner circumferential surface 3a of the outer ring 3 and the outer circumferential surface 5b of the retainer 5, and a circumferential clearance Gb, also known as the "pocket clearance," is formed between the balls 4 and the pocket forming surface 7 of the retainer 5. By setting these various clearances, good operation of the rolling bearing 1 can be ensured.

[0045] In the rolling bearing 1 of this embodiment, the second radial clearance Ga2 is smaller than the first radial clearance Ga1. Therefore, the rolling bearing 1 of this embodiment is an angular contact ball bearing in which the guiding surface Sa is formed by the inner circumferential surface 3a of the outer ring 3 and the guided surface Sb is formed by the outer circumferential surface 5b of the retainer 5, and the second radial clearance Ga2 constitutes the "guiding clearance".

[0046] Taking the case where the inner diameter of the outer ring 3 (the diameter of the guide surface Sa) is designed to be 95.26 mm, the outer diameter of the retainer 5 (the diameter of the guided surface Sb) is designed to be 95 mm, and the ball diameter is designed to be 8.73 mm as an example, the characteristic structure of the rolling bearing 1 of this embodiment having the above structure will be described. In addition, in this case, the design value δ of the second radial clearance Ga2, which is the guide clearance, is 0.26 mm.

[0047] The retainer 5 of the rolling bearing 1 forms two types of pockets with different opening sizes (pocket diameters) W, which are respectively composed of circular holes as multiple pockets 6. That is, there is a large pocket 6A and a small pocket 6B with a pocket diameter W smaller than that of the large pocket 6A, and at least one large pocket 6A and one small pocket 6B are provided. In this embodiment, a total of 24 pockets 6 are arranged at 15° intervals, such as Figure 4 As shown, three large pocket groups BG, which consist of four consecutive large pockets 6A in the circumferential direction, and four small pocket groups SG, which consist of four consecutive small pockets 6B in the circumferential direction, are alternately arranged in the circumferential direction.

[0048] The balls 4 housed in each pocket 6 are shared balls of the same diameter. Therefore, the circumferential clearance Gb between the pocket forming surface 7 (large pocket forming surface) forming the large pocket 6A and the ball 4 is larger than the circumferential clearance Gb between the pocket forming surface 7 (small pocket forming surface) forming the small pocket 6B and the ball 4. Hereinafter, when explaining the two circumferential clearances Gb of different sizes, the former will be referred to as "large pocket clearance Gb1" and the latter as "small pocket clearance Gb2".

[0049] The diameter W of the large pocket 6A and the small pocket 6B is set to the size δ0 of the guide clearance (second radial clearance Ga2) when the bearing is running. The first inequality (size relationship) satisfies ε2<δ0<ε1 between the size ε1 of the large pocket clearance Gb1 and the size ε2 of the small pocket clearance Gb2.

[0050] Here, the guide clearance δ0 during bearing operation is calculated based on the bearing temperature T under operating conditions considering the high-speed rapid rotation phenomenon of the retainer 5. As described above, the high-speed rapid rotation phenomenon occurs even when the dn value, calculated as the product of the inner diameter [mm] and the rotational speed [rpm] of the rolling bearing, is approximately 1,500,000 or less (dn ≤ 1,500,000), and the bearing temperature at this time is T ≒ 30 [°C]. Furthermore, in the case where the guide ring is the outer ring 3, as in the rolling bearing 1 of this embodiment (where the guide surface Sa is provided on the outer ring 3), the guide clearance δ0 during bearing operation can be calculated using the following formula.

[0051] δ0=δ+d r ·(T-20)·α r -d c ·(T-20)·α c

[0052] In addition, the parameters in the above formula are: δ: design value of guide clearance [mm], T: bearing temperature [°C], d r : Diameter of guide surface Sa [mm], d c : Diameter of the guided surface Sb [mm], α r The linear expansion coefficient [1 / ℃] of the outer ring 3 (forming material), α c The linear expansion coefficient of retainer 5 [1 / ℃], where δ: 0.26, T: 30, d r 95.26, d c 95.0, α r 12.5×10 -6 α c 50×10 -5 The coefficient of linear expansion of the outer ring 3 is that of SUJ2 bearing steel as specified in JIS G 4805, and the coefficient of linear expansion of the retainer 5 is that of the phenolic resin of the fabric substrate. In this case, δ0 = 0.22 mm.

[0053] As described above, with the diameter of ball 4 being 8.73 mm and the guide clearance δ0 being 0.22 mm during bearing operation, in order to make the first inequality ε2 < δ0 < ε1 hold, for example, the diameter W of the large pocket 6A is made 9.13 mm, the size ε1 of the large pocket clearance Gb1 is made 0.4 mm, and the diameter W of the small pocket 6B is made 8.93 mm, the size ε2 of the small pocket clearance Gb2 is made 0.2 mm.

[0054] For reference Figure 9A , Figure 9B and Figure 10A , Figure 10BAs explained, when the rolling bearing 1, which consists of an inner ring 2 and an outer ring 3 rotating relative to each other, operates, the frictional force generated by the contact between the retainer 5 and the raceway rings and the frictional force generated by the contact between the retainer 5 and the balls 4 are in opposite directions. Therefore, in the rolling bearing 1 of this embodiment, by generating the two frictional forces in a balanced manner during bearing operation, the other frictional force is used to reduce or offset one of the two frictional forces that cause the high-speed spinning phenomenon.

[0055] Specifically, as a pocket 6 for storing the ball bearing 4, a large pocket 6A and a small pocket 6B with an opening size W smaller than that of the large pocket 6A are provided, and the first inequality (size relationship) satisfying ε2<δ0<ε1 is true.

[0056] In this case, by the radial displacement of the retainer 5 during bearing operation, it is possible to switch between the contact between the ball 4 and the pocket forming surface 7 of the small pocket 6B, and the contact between the inner circumferential surface 3a (guide surface Sa) of the outer ring 3 and the outer circumferential surface 5b (guided surface Sb) of the retainer 5. Thus, one of the two frictional forces, which are in opposite directions, can be reduced or counteracted by the frictional force of the other, thereby suppressing the occurrence of high-speed rapid rotation.

[0057] Furthermore, in order to perform the aforementioned functions during bearing operation, even under conditions such as thermal expansion of the outer ring 3 and the cage 5, it is necessary to switch the contact object of the cage 5 between the ball 4 and the outer ring 3 by displacement of the cage 5. Therefore, in the first inequality described above, the design value of the guide clearance δ is not used, but the size of the guide clearance δ0 during bearing operation is used. Normally, the size of the guide clearance δ0 during bearing operation decreases relative to the design value δ due to expansion caused by heat and centrifugal force. This reduction (δ-δ0) is at most about 0.5 mm under conditions of high-speed rapid rotation, thus satisfying the second inequality 0 mm < (δ-δ0) < 0.5 mm. Here, since δ = 0.26 mm and δ0 = 0.22 mm, the second inequality holds.

[0058] As described above, even if large pockets 6A and small pockets 6B with different opening sizes W are provided, depending on the configuration of the pockets 6 and the relationship with the guide gap Ga2, it is possible that only the pocket forming surface 7 of the small pocket 6B can contact the ball 4, while the inner circumferential surface 3a (guide surface Sa) of the outer ring 3 and the outer circumferential surface 5b (guided surface Sb) of the retainer 5 cannot contact. In this case, the expected rapid rotation suppression effect cannot be achieved. Therefore, in the rolling bearing 1 of this embodiment, when the area surrounded by the line of the outer edge of the connecting scatter plot is defined as the "retainer movable area", the retainer movable area is made into a non-circular shape with a circle whose diameter is the size δ0 of the guide clearance Ga2 when the bearing is running as the circumcircle. The pocket clearance Gb2 of the small pocket 6B, the design value δ of the guide clearance Ga2, and the configuration of the large pocket 6A and the small pocket 6B are studied. The scatter plot is obtained by drawing the positions of numerous retainers 5 that can exist without contacting the track rings 2, 3 and the ball 4 on a two-dimensional coordinate. Figure 5 It shows that Figure 4 The retainer movable area 10 of the retainer 5 is configured with a large pocket 6A and a small pocket 6B as shown.

[0059] Figure 5 The movable region 10 of the retainer shown is a non-circular shape with a circle 11 whose diameter is the guide clearance δ0 (=0.22 mm) during bearing operation as its circumcircle, and contacts the circle 11 at multiple locations. The contact portion 12 of the movable region 10 that contacts the circle 11 is an arc shape with a length in the circumferential direction of the circle 11, and six such arc-shaped contact portions 12 are provided at equal intervals along the circumferential direction of the circle 11. Therefore, the movable region 10 of the retainer of the rolling bearing 1 of this embodiment has six arc-shaped contact portions 12 that contact the circle 11 (circumcircle) and six non-contact portions 13 that do not contact the circle 11 in the circumferential direction of the circle 11. The arc-shaped contact portion 12 represents the range in which the retainer 5 contacts the guide surface Sa (inner circumferential surface 3a of the outer ring 3), and the non-contact portion 13 represents the range in which the pocket forming surface 7 of the retainer 5 contacts the ball 4.

[0060] The movable region 10 of the retainer indicates that the retainer 5 can move freely without contacting other components (inner ring 2, outer ring 3, and balls 4). Therefore, if the center of the retainer 5 is located within the movable region 10 when the bearing is running, the center of the retainer 5 is subjected to centrifugal force and moves towards the outer edge of the movable region 10. When the center of the retainer 5 reaches the outer edge of the movable region 10, the retainer 5 contacts the inner circumferential surface 3a (guide surface Sa) of the outer ring 3 or the balls 4 and is subjected to frictional force in the tangential direction, moving along the outer edge of the movable region 10. At this time, in the area (arc-shaped contact portion 12) of the outer edge of the movable region 10 that contacts the circle 11 (circumscribed circle), a frictional force F1 is applied to the retainer 5 through contact with the guide surface Sa. In the area (non-contact portion 13) that does not contact the circle 11, a frictional force F2 opposite to the aforementioned frictional force F1 is applied to the retainer 5 through contact with the balls 4. Therefore, during bearing operation, the two frictional forces F1 and F2, which are in opposite directions, act alternately on the retainer 5, thus appropriately reducing one of the frictional forces F1 and F2. This effectively prevents the occurrence of high-speed rapid rotation.

[0061] Furthermore, the rolling bearing 1 of this embodiment prevents high-speed rapid rotation by providing pockets 6 (large pocket 6A and small pocket 6B) on the retainer 5, which are composed of two circular holes of different sizes with different opening dimensions W. Compared with the technical means described in Patent Document 1, this can be easily and cost-effectively implemented. In particular, in the structure of the rolling bearing 1 of this embodiment, the guide surface Sb of the retainer 5 is not always in contact with the guide surface Sa of the track ring. The contact frequency between the guide surface Sa and the guide surface Sb is suppressed, so wear can be suppressed even without precision machining these surfaces.

[0062] Here, for reference, according to Figure 6 This section briefly explains how to determine the position where the retainer 5 can exist without contacting the ball 4, which is required when determining the movable area 10 of the retainer mentioned above.

[0063] Figure 6 This is a conceptual diagram showing a portion of the retainer 5 and two balls 4 housed in the pocket 6 of the retainer 5 after extraction. In this diagram, label O represents the axis, label C represents the center of the retainer 5, label B represents the center of the ball 4, and label P represents any point on the pocket-forming surface 7 of the retainer 5. Furthermore, the left-hand character of the subscript in label B and the subscript in label P indicates the number of the ball 4 and the pocket 6 housing it, while the right-hand character of the subscript in label P indicates the j-th point when the pocket-forming surface 7 is discretized (mesh-divided).

[0064] First, from the center B of ball 4 i Any point P on the pocket-forming surface 7 of the pocket 6 that houses the ball 4. i,j The magnitude (absolute value d) of the vector is compared with the radius (r) of ball 4. If the absolute value d is greater than the radius r of the ball 4, then point P is determined to be on the pocket forming surface 7. i,j It does not interfere with ball bearing 4. When the absolute value d is less than or equal to the radius r of the ball 4, point P is determined to be on the pocket forming surface 7. i,j Interference with ball bearing 4.

[0065] Then, perform the same decision-making process for other points P.

[0066] In addition, Figure 5 In the example shown, it can be said that point P on the pocket-forming surface 7 of the pocket 6 that houses the ball 4 with the center indicated by label B1. 1,j Point P 1,j+1 Point P on the pocket forming surface 7 of the pocket 6 that houses the ball 4, which is not interfered with by the ball 4 and has the ball 4 centered as indicated by label B2. 2,j Point P 2,j+1 Interference with ball bearing 4.

[0067] Furthermore, if f(i,j) = dr, and the relation f(i,j) > 0 holds for all i and j, then the position of the retainer center C can be considered a point where the retainer 5 can exist without contacting the ball 4. Also, if the position of the retainer center C is within a circle centered on the shaft and with the guide clearance as its diameter, then the retainer 5 can also exist without contacting the raceway. Therefore, a point satisfying both of these conditions is determined to be a point that can exist without contacting either the ball or the raceway.

[0068] Next, the position of the retainer center C and the phase of the retainer are changed, and the same determination operation as that performed in the first step described above is performed. Then, if there is a phase at the selected retainer center C position that is determined to be a "point on the movable area of ​​the retainer" as described above, then the selected retainer center C position is determined to be a "point on the movable area of ​​the retainer".

[0069] The rolling bearing 1 according to the embodiments of the present invention has been described above, but the embodiments of the present invention are not limited thereto, and various modifications can be made without departing from the spirit of the present invention.

[0070] For example, the configuration of the large pocket 6A and the small pocket 6B provided in the retainer 5 can be appropriately changed to take into account the ease of manufacturing the retainer 5, the ability to suppress rapid rotation, thermal balance, and other factors. Figure 7 The arrangement of the two pockets 6A and 6B is shown. Figure 4 The retainer movable region 10 of different retainers 5 (retainers 5 with a total of 24 pockets 6) and the circle 11 with a diameter of the guide clearance δ0 (=0.22mm) during bearing operation are arranged alternately in the circumferential direction of the retainer movable region 10, with two arc-shaped contact portions 12 that are in line contact with the circle 11 and two non-contact portions 13 that are not in contact with the circle 11. Although detailed drawings are omitted, the retainer movable region 10 is the retainer movable region of the retainer 5 with two large pocket groups BG consisting of six large pockets 6A arranged consecutively and two small pocket groups SG consisting of six small pockets 6B arranged consecutively.

[0071] Here, according to Figure 8 An example is given where the rapid rotation suppression effect described above cannot be properly enjoyed due to the configuration of the large pocket 6A and the small pocket 6B. Figure 8 The diagram shows the movable region 10 of the retainer and the circle 11 with a diameter equal to the guide clearance δ0 (=0.22 mm) during bearing operation in a rolling bearing 1 with the above-described structure, where a retainer 5 is used. The retainer 5 has a total of 24 pockets 6, each consisting of six consecutive groups of two large pockets 6A arranged as large pockets BG and six consecutive groups of two small pockets 6B arranged as small pockets SG. As shown in the diagram, the movable region 10 of the retainer in this case does not have a contact portion that contacts the circle 11; it is not in contact with the circle 11 around its entire circumference. That is, during bearing operation, the retainer 5 does not contact the guide surface Sa of the raceway; only the small pockets 6B of the retainer 5 contact the balls 4. In this case, only a unidirectional frictional force F2 acts on the retainer 5, i.e., only the frictional force that causes high-speed rapid rotation acts; therefore, it is impossible to prevent high-speed rapid rotation.

[0072] The rolling bearing 1 described above has a guide surface Sa of the guide retainer 5 on the outer ring 3. However, the present invention can also be applied to a rolling bearing 1 with a guide surface Sa of the guide retainer 5 on the inner ring 2, that is, a rolling bearing 1 in which the guide clearance during bearing operation is formed by the first radial clearance Ga1 between the outer peripheral surface 2a of the inner ring 2 and the inner peripheral surface 5a of the retainer 5. In this case, the formula for calculating the size δ0 of the guide clearance during bearing operation is as follows.

[0073] δ0=δ+d c ·(T-20)·α c -d r·(T-20)·α r

[0074] The parameters in this calculation formula are: δ: design value of guide clearance [mm], T: bearing temperature [°C], d r : Diameter [mm] of the guiding surface Sa (outer peripheral surface 2a of inner ring 2), d c : Diameter [mm] of the guided surface Sb (inner circumferential surface 5a of retainer 5), α r The linear expansion coefficient [1 / ℃] of the inner ring 2 (forming material), α c : Coefficient of linear expansion of retainer 5 [1 / ℃].

[0075] Furthermore, the rolling elements constituting the rolling bearing 1 can also be rollers (cylindrical rollers, needle rollers, etc.) instead of balls 4. That is, the present invention can be applied not only to ball bearings, but also to roller bearings such as cylindrical roller bearings and needle roller bearings.

[0076] As explained above, the present invention effectively prevents high-speed rapid rotation of the retainer 5 constituting the rolling bearing 1, and is therefore particularly preferred for use in rolling bearings used in applications where high-speed rapid rotation is prone to occur. For example, in the case of ball bearings used to support the spindle of a machine tool or the reaction wheel of a spacecraft, these ball bearings are subjected to relatively large axial preload during use. Specifically, there are many cases where the ratio of the radial load Fr to the axial load Fa (=Fr / Fa) during operation is 3 or less, and in such cases, high-speed rapid rotation is particularly likely to occur. This is because the more constant the spacing of the rolling elements (balls), the more likely high-speed rapid rotation will occur. Conversely, when the radial load acting on the ball bearing is particularly large compared to the axial load (for example, the ratio Fr / Fa exceeds 3 as described above), the balls are delayed and the spacing of the balls becomes uneven, thus making high-speed rapid rotation less likely to occur. Therefore, the present invention is particularly preferred for use in ball bearings used in applications such as machine tool spindles and reaction wheel support bearings of space equipment where the relationship Fr / Fa≤3.0 holds.

[0077] The rolling bearing 1 of the present invention has been described above, but the present invention is not limited to any of the embodiments described above, and can be implemented in various ways without departing from the spirit of the present invention. The scope of the present invention is indicated by the claims, and also includes all equivalents and modifications within the scope of the claims.

[0078] Label Explanation

[0079] 1: Rolling bearing; 2: Inner ring; 3: Outer ring; 4: Ball (rolling element); 5: Retainer; 6: Pocket; 6A: Large pocket; 6B: Small pocket; 7: Pocket forming surface; 10: Retainer movable area; 11: Circle; 12: Contact part; 13: Non-contact part; BG: Large pocket group; SG: Small pocket group; F, F1, F2: Friction force; Ga1: First radial clearance (guide clearance); Ga2: Second radial clearance (guide clearance); Gb: Circumferential clearance; Sa: Guide surface; Sb: Guided surface; W: Opening size (pocket diameter); δ: Design value of guide clearance (radial clearance); δ0: Size of guide clearance (radial clearance) during bearing operation; ε1: Size of large pocket clearance; ε2: Size of small pocket clearance.

Claims

1. A rolling bearing, comprising: A pair of track rings, the pair of track rings being arranged radially opposite each other and rotating relative to each other via a plurality of rolling elements; and The retainer is annular in shape and has multiple pockets spaced apart circumferentially to accommodate the rolling elements. One of the pair of track rings has an annular guide surface, and the retainer has an annular guided surface radially opposite the guide surface. Each pocket is composed of a circular hole with a constant opening size along the radial direction. Its features are, At least one of the plurality of pockets is a large pocket, and the remaining pockets are small pockets with an opening size smaller than the large pocket. When the design value of the radial clearance formed between the guide surface and the guided surface is set as δ, the size of the radial clearance during bearing operation is set as δ0, and the sizes of the circumferential clearances between the large pocket forming surface and the small pocket forming surface of the retainer in a neutral state and the rolling element are set as ε1 and ε2 respectively, the inequalities ε2<δ0<ε1 and 0mm<(δ-δ0)<0.5mm are satisfied, and... When the area enclosed by the line connecting the outer edge of the scatter plot is defined as the movable area of ​​the retainer, the movable area of ​​the retainer has a non-circular shape with a circle whose diameter is the size δ0 of the radial clearance when the bearing is running as the circumcircle. The scatter plot is obtained by drawing a number of positions on a two-dimensional coordinate system where the retainer can exist without contacting the pair of track rings and the rolling elements.

2. The rolling bearing according to claim 1, wherein, The contact portion between the movable area of ​​the retainer and the circumferential circle is an arc shape having a length in the circumferential direction of the circumferential circle, and multiple arc-shaped contact portions are provided at intervals in the circumferential direction of the circumferential circle.

3. The rolling bearing according to claim 2, wherein, The arc-shaped contact portion is provided in three or more at equal intervals along the circumference of the circumference of the outer circle.

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