JP2006211863A - Direct drive motor and bearing therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a direct drive motor capable of receiving radial load and moment load, receiving axial load in both directions, achieving reduction in space in the axial direction, reduction in torque, increase in speed, high rotation accuracy (low vibration), and high rigidity; and to provide a bearing for the direct drive motor. <P>SOLUTION: In a single row or a double row ball bearing, a rolling bearing supporting a rotor in a rolling-free state with respect to the stator of the direct drive motor includes an inner ring 102, an outer ring 101 arranged around the outer periphery of the inner ring 102, and a plurality of balls 103 freely rotatably assembled between the inner ring 102 and the outer ring 101. A sectioned dimension ratio (B/H) between an axially sectioned width B and a radially sectioned height H is set to be less than 0.63 (B/H<0.63) in case of a single row, and is set to be less than 1.2 (B2/H2<1.2) in case of a double row. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a direct drive motor that directly drives a load without using a reduction gear. The present invention also relates to a direct drive motor bearing that rotatably supports a rotor of a direct drive motor with respect to a stator of the motor.

  FIG. 30 shows an example of a conventional direct drive motor. In the figure, reference numeral 10 denotes a direct drive motor. The direct drive motor 10 includes a stator (stator) 11 and a rotor (rotor) 12. The stator 11 has a stator core 11a formed in a cylindrical shape, and a stator coil 11b is wound around the stator core 11a. On the other hand, the rotor 12 has a cylindrical rotor core 12a disposed on the outer periphery of the stator core 11a, and a rotor magnet 12b is attached to the inner peripheral surface of the rotor core 12a. The rotor magnet 12b faces the stator coil 11b of the stator 11. Therefore, when an excitation current is applied to the stator coil 11b of the stator 11, the rotation generated between the stator coil 11b and the rotor magnet 12b. The rotor 12 is rotated by the force.

  The direct drive motor 10 also includes a rolling bearing 13 (in this case, a cross roller bearing is shown) that rotatably supports the rotor 12 with respect to the stator 11. The rolling bearing 13 includes an inner race ring (hereinafter referred to as “inner ring”) 13 a fixed to the stator core 11 a of the stator 11, an outer race ring (hereinafter referred to as “outer ring”) 13 b disposed on the outer periphery of the inner ring 13 a, and an inner ring. The outer ring 13 b is fixed to the rotor core 12 a of the rotor 12, and includes a plurality of rolling elements 13 c that are rotatably incorporated between the outer ring 13 b and the outer ring 13 b. A pulsar ring 14 is attached to the rotor core 12a of the rotor 12, and the rotational speed of the rotor 12 is controlled by a controller (not shown) by detecting the unevenness of the pulsar ring 14 with a position detector 15. It has come to be.

  By the way, as a function required for the rolling bearing which supports the rotor of such a direct drive motor rotatably with respect to the stator, it has high rotational accuracy and high rigidity (particularly, high moment rigidity). In addition, the motor structure can be simplified and space can be saved. Therefore, in a conventional direct drive motor, as a rolling bearing (hereinafter referred to as “rotor support bearing”) that rotatably supports a rotor with respect to a stator, for example, as shown in Patent Document 1 or Patent Document 2 Often, cross roller bearings are used.

  As shown in FIG. 27, the cross roller bearing uses a cylindrical roller as the rolling element 3 incorporated between the inner ring 1 and the outer ring 2, so that the radial load and the axial load in both directions and It can receive moment load and can save space. However, since the rolling contact surface of the rolling element (roller) 3 is in line contact with the raceway grooves 1a and 2a of the inner ring 1 and the outer ring 2, the bearing ring is rotated as compared with a ball bearing using a ball as the rolling element. However, a relatively large torque is required. For this reason, since the rotation performance of the raceway is low, and frictional heat is likely to be generated at the contact portion with the raceway, it is difficult to use in applications where high-speed rotation is required. Further, there is a problem that the contact state of the line contact portion becomes unstable due to minute deformation when the shaft or the housing is incorporated, and as a result, torque unevenness (torque fluctuation) is likely to occur.

In addition, when a cross roller bearing is used as a rotor support bearing for a direct drive motor, a preload is often applied to the bearing in order to achieve high rigidity and high accuracy (precision rotational runout accuracy). However, when a preload is applied to the cross roller bearing, the rotational performance, heat generation, torque fluctuation and the like of the raceway are further reduced. Therefore, for example, double row angular contact ball bearings (see FIG. 28) in which angular ball bearings as shown in Patent Document 3 or Patent Document 4 are combined in two rows, ultrathin angular ball bearings or deep groove ball bearings in two rows. It has been studied to use a combination (see FIG. 29) as a bearing for supporting a rotor of a direct drive motor.
Japanese Utility Model Publication No. 1-444806 JP 63-213457 A Japanese Utility Model Publication No. 5-66327 JP 2003-278765 A

  However, using double-row combination angular contact ball bearings as bearings for direct drive motor rotors can improve the rotational performance, heat generation, torque fluctuation, etc. of the bearing ring, but approximately twice that of single-row ball bearings. This requires a space in the axial direction and does not contribute to space saving. On the other hand, if an ultra-thin combined bearing as shown in FIG. 29 is used as a bearing for supporting a rotor of a direct drive motor, it is advantageous in terms of space saving, but the ring thickness of the inner ring 7 and the outer ring 8 is very large. Therefore, it is difficult to obtain desired processing accuracy (particularly roundness). In addition, the rigidity of the inner ring 7 and outer ring 8 is also low, so it is easy to press with peripheral parts such as bearing tightening nuts and outer ring pressers when assembled into a shaft or housing (especially when assembled with clearance fitting). There is also a problem that it may be deformed and it takes time and effort to ensure the accuracy of incorporation. Further, depending on the case, the deformation at the time of incorporation may cause distortion in the raceway grooves of the inner ring 7 and the outer ring 8, and an uneven load may be applied to the contact portion between the raceway grooves of the inner ring 7 and the outer ring 8 and the ball 9, Rolling movement may be inhibited.

  The present invention has been made in view of such problems, and can receive radial load, axial load in both directions and moment load, and can save space in the axial direction, reduce torque, increase speed, An object of the present invention is to provide a direct drive motor and a bearing for the direct drive motor that can achieve high rotational accuracy (low vibration) and high rigidity.

  In order to achieve the above object, a direct drive motor according to the invention of claim 1 includes a rotor, a stator arranged inside or outside the rotor, and the rotor with respect to the stator. In a direct drive motor that includes a rolling bearing that is rotatably supported, and that directly drives a load without using a reduction gear, the rolling bearing includes an inner ring, an outer ring disposed on an outer periphery of the inner ring, and the inner ring. And a plurality of balls rotatably incorporated between the outer ring and the outer ring, and a cross-sectional dimension ratio (B / H) is (B / H) <0.63.

  A direct drive motor bearing according to a second aspect of the present invention includes an inner ring, an outer ring disposed on an outer periphery of the inner ring, and a plurality of balls that are rotatably incorporated between the inner ring and the outer ring. A direct drive motor bearing comprising a single-row ball bearing and rotatably supporting a rotor of a direct drive motor that directly drives a load without using a speed reducer, the axial cross-sectional width of the ball bearing The cross-sectional dimension ratio (B / H) between B and the radial cross-sectional height H is (B / H) <0.63.

  According to a third aspect of the present invention, there is provided a direct drive motor comprising: a rotor; a stator disposed inside or outside the rotor; and a rolling bearing that rotatably supports the rotor with respect to the stator. In the direct drive motor that directly drives a load without using a reduction gear, the rolling bearing is configured to roll between an inner ring, an outer ring disposed on an outer periphery of the inner ring, and the inner ring and the outer ring. A double-row ball bearing including a plurality of freely incorporated balls, the cross-sectional dimension ratio (B2 / H2) between the axial cross-sectional width B2 and the radial cross-sectional height H2 is (B2 / H2) <1 .2.

  A direct drive motor bearing according to a fourth aspect of the present invention includes an inner ring, an outer ring disposed on an outer periphery of the inner ring, and a plurality of balls that are rotatably incorporated between the inner ring and the outer ring. A bearing for a direct drive motor comprising a double row ball bearing and rotatably supporting a rotor of a direct drive motor that directly drives a load without using a speed reducer, the axial section of the double row ball bearing The cross-sectional dimension ratio (B2 / H2) between the width B2 and the radial cross-sectional height H2 is (B2 / H2) <1.2.

The invention according to claims 1 and 2 will be described.
Here, FIG. 22 and FIG. 23 show the standard thin ball bearings (bearing inner diameter: φ38.1 mm, bearing outer diameter: φ47.625 mm, bearing width: 4.762 mm, cross-sectional dimension ratio ( B / H) = 1) as a reference, the radius of the inner and outer races when the bearing inner diameter is changed without changing the bearing outer diameter and the bearing width (that is, when the value of (B / H) is changed). direction of deformation characteristics (refer to FIG. 20: this illustrates the inner ring in this case) and the radial moment of inertia of area I of the inner and outer raceway: indicates (see FIG. 21 I = bh for a ^3/12) and result of comparison ing.

  FIGS. 24 and 25 show ultra-thin ball bearings that are used as standard (bearing inner diameter: φ63.5 mm, bearing outer diameter: φ76.2 mm, bearing width: 6.35 mm, cross-sectional dimension ratio (B / H) = 1) as a reference, the radial direction of the inner and outer races when the bearing inner diameter is changed without changing the bearing outer diameter and bearing width (that is, when the value of (B / H) is changed) 3 shows a result of comparison between the deformation characteristics of the inner ring and the secondary moment I in the radial direction of the inner and outer races.

In any of the bearings, (B / H) = 0.63, and the change in the rigidity increase rate gradient is noticeable. That is, the increase in the cross-sectional secondary moment I becomes remarkable, and the decrease in the amount of deformation in the radial direction of the raceway ring becomes saturated.
Therefore, in the present invention, it is possible to prevent the raceway ring from being deformed due to the lathe processing during the production of the raceway or the grinding force during the grinding process, which is a problem with the conventional ultra-thin bearing, and the bearing with roundness, uneven thickness, etc. Accuracy can be improved.

In addition, when incorporated in a shaft or housing (especially when assembled by clearance fitting with the shaft or housing), deformation of the bearing ring when the bearing is fixed with a bearing tightening nut or outer ring presser (especially roundness) (Deterioration) can be suppressed, and defects such as torque failure and rotation accuracy caused by deformation, increased heat generation, wear and seizure can be prevented.
That is, as compared with the conventionally used ultra-thin ball bearings, it is possible to achieve both space saving and high accuracy. In addition, since each ball always makes point contact with the raceway groove of the raceway at two points, torque increase due to the rolling contact surface of the roller making linear contact with the raceway groove like a cross roller bearing, etc. There is no problem of torque unevenness, low heat generation, and prevention of wear can be realized.

  Furthermore, when the width dimension is about half that of the conventional standard single row ball bearing, the ball diameter is also about half that of the conventional ball bearing, but conversely the number of balls per row increases, and the bearing rigidity is More than ball bearings. For direct drive motors, the rotational speed is lower than in other applications, so rolling fatigue life time is reduced due to a decrease in the bearing load capacity due to the reduced ball diameter, even in consideration of future high-speed trends. There is no problem in practical use.

If the ball bearing is a single row, it is difficult to apply a preload to the bearing or apply a moment load. However, if the ball bearing is a double row or more, a radial load, an axial load, a moment load, etc. Can be loaded onto the bearing.
On the other hand, in the standard ball bearings whose dimension series defined by the International Organization for Standardization (ISO) are 18 (for example, 6800), 19 (for example, 6901), 10 (for example, 6003), 02 (for example, 7205A), 03 (for example, 7307A) When the inner diameter of the bearing is φ5 mm to φ500 mm, the cross-sectional dimension ratio (B / H) is set to 0.63 to 1.17.

Therefore, the width of the conventional standard single-row ball bearing is the largest in width by setting it to about 1/2 times the maximum value 1.17 of the sectional dimension ratio (B / H) of these ball bearings, that is, less than 0.63. The single-row ball bearings according to claim 1 and 2 can be arranged in a combination of two rows within a narrower width than a narrow ball bearing and within an axial width space of a conventional standard single-row ball bearing.
For example, if the sectional dimension ratio (B / H) of a conventional ball bearing is (B / H) = 0.9, the sectional dimension ratio (B / H) of the bearing of the present invention is (B / H) = 0. .45. Moreover, it is not necessary for the two ball bearings to be combined to have the same cross-sectional dimension ratio (B / H). For example, one of the ball bearings may be 0.50 and the other may be 0.40.

  Further, the operation of the invention according to claims 3 and 4 will be described. For example, as shown in FIG. 16, between the double row raceway grooves 201a and 201b of the outer ring 201 and the double row raceway grooves 202a and 202b of the inner ring 202, In the double-row ball bearing 200 in which a large number of balls 203 are rotatably arranged, an axial sectional width B2 and a radial sectional height H2 (= (outer ring outer diameter D2-inner ring inner diameter d2) / 2) and The cross-sectional dimension ratio (B2 / H2) is (B2 / H2) <1.2.

  In the double row ball bearing, by setting the cross-sectional dimension ratio (B2 / H2) as described above, the conventional standard is the same as when the single row narrow ball bearing according to claim 1 is combined in two rows. The double-row ball bearing according to claim 3 can be disposed in the axial width space of the single-row ball bearing, and it is also possible to apply a preload or to apply a moment load. Other functions and effects are the same as those obtained when the single-row narrow ball bearing according to claim 1 is combined in two rows.

  FIG. 26 is a comparison of calculated moment stiffness of various bearings. The single-row narrow angular contact ball according to claim 1 having the same size (calculation example is equivalent to bearing name No. 7906A (contact angle 30 °) and the inner and outer diameters are the same: inner ring inner diameter φ30 mm, outer ring outer diameter φ47 mm). The present invention examples A to E in which the bearings (contact angle 30 °: calculation example of the total ball bearing) are combined in two rows and the raceway groove radius of the race is changed are all standard double row angular contact ball bearings and crosses Moment rigidity is larger than that of roller bearings. For example, the present invention example B can maintain a moment rigidity of 1.9 times that of a standard two-row angular contact ball bearing and 2.4 times that of a cross roller bearing.

Each design preload clearance is calculated as a practical standard value of Examples A to E of the present invention, -0.010 mm for the standard two-row combination angular contact ball bearing, and -0.001 mm for the cross roller bearing. (If a preload design smaller than -0.001 mm is used with a cross roller bearing, the bearing torque becomes excessive and may become unusable in practice).
The appropriate ball diameter of the narrow ball bearing according to the present invention varies depending on whether or not a seal or the like is attached, but in order to increase rigidity, if the ball diameter is extremely reduced, the ball and the raceway groove of the bearing ring Since the surface pressure between the contact portions is increased and the pressure scar resistance is lowered, generally 30 to 90% of the bearing width (B) or (B2 / 2) is desirable.

Furthermore, when the present invention is applied to an angular ball bearing, the contact angle of the bearing is selected according to the required rigidity (for example, moment rigidity) and the required torque, but is preferably in the range of approximately 10 ° to 60 °.
Furthermore, according to the direction and magnitude of the load, the contact angle of the combined bearings or the contact angle between the rows in the case of a double row bearing may be changed as necessary.
Furthermore, the curvature radii of the inner ring raceway groove and the outer ring raceway groove are 51 to 60% Da (Da: ball diameter), preferably 52 to 56% Da, more preferably 52, depending on the required rigidity and torque characteristics. About 54% Da. Further, the radius of curvature of the inner ring raceway grooves and the radius of curvature of the outer ring raceway grooves may not be the same, or may be different between single row bearings combined or between rows of double row bearings.

  According to the first to fourth aspects of the present invention, it is possible to receive radial loads, both axial loads and moment loads, and to save space in the axial direction, lower torque, higher speed, and higher rotational accuracy (lower vibration). Since high rigidity can be achieved, it is possible to simultaneously increase the speed of the direct drive motor, improve the positioning accuracy, and make it compact.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. 30 identical to those shown in FIG. 30 are assigned the same reference codes as in FIG. 30, and detailed descriptions thereof are omitted.
FIG. 1 is a partial cross-sectional view showing a schematic configuration of a direct drive motor according to a first embodiment of the present invention. As shown in the figure, two single row ball bearings 100 are combined in a back-to-back manner between the stator 11 and the rotor 12 of the direct drive motor according to the first embodiment of the present invention. A row combination ball bearing 16 is provided as a rotor support bearing.

As shown in FIG. 2, each single row ball bearing 100 constituting the two-row combination ball bearing 16 has a large number of balls 103 that can freely roll between a raceway groove 101 a of the outer ring 101 and a raceway groove 102 a of the inner ring 102. In the single-row all-round angular contact ball bearing arranged, the cross-sectional dimension ratio (B /) between the axial cross-sectional width B and the radial cross-sectional height H (= (outer ring outer diameter D−inner ring inner diameter d) / 2). H) is (B / H) <0.63.
Here, in the first embodiment, as shown in FIG. 3, two single-row angular contact ball bearings 100 are used as a double-row back side combination and replaced with a double-row combination angular contact ball bearing of 7208A (contact angle 30 °). Take an example.

  The 7208A angular contact ball bearing has an inner ring inner diameter φ40 mm, an outer ring outer diameter φ80 mm, and an axial sectional width (bearing single body width) B of 18 mm, so the sectional dimension ratio (B / H) = 0.9. Therefore, in the angular ball bearing 100 of the present embodiment, the sectional dimension ratio (B / H) = 0.45 (the inner ring inner diameter and the outer ring outer diameter remain the same, and the axial sectional width (bearing single body width) is 9 mm). Yes. As a result, it is possible to receive a radial load, an axial load in both directions, and a moment load, and to achieve a space saving of 1/2 in the axial dimension, a reduction in torque, and a further increase in rigidity.

Of course, if necessary, the sectional dimension ratio (B / H) of the angular ball bearing 100 may be set to be less than 0.45 or more than 0.45 (provided that (B / H) <0.63). Absent. Incidentally, the contact angle of the angular ball bearing 100 is, for example, 30 °.
In this embodiment, the pitch circle diameter of the balls 103 is as shown in the following formula (1). However, when it is desired to increase the moment rigidity by increasing the number of balls per row, the following formula (2) is adopted. Then, the pitch circle diameter of the ball 103 may be shifted to the outer ring side, and the structure shown in FIG. 4 may be adopted. If necessary, the following equation (3) is adopted to conversely change the pitch circle diameter of the ball 103 to the inner ring 102 side. It may be shifted to (not shown).
Ball pitch circle diameter = (inner ring inner diameter + outer ring outer diameter) / 2 (1)
Ball pitch circle diameter> (inner ring inner diameter + outer ring outer diameter) / 2 (2)
Ball pitch circle diameter <(inner ring inner diameter + outer ring outer diameter) / 2 (3)

  Further, if necessary, as shown in FIG. 5, the ball pitch circle diameters of the left and right ball bearings to be combined may not be the same value, and the diameters of the balls 103 of the left and right ball bearings to be combined may not be the same value. May be. In addition, the sectional dimension ratio (B / H) of the two ball bearings to be combined is not the same. For example, the smaller ball diameter is (B / H) = 0.28, and the larger ball diameter is (B / H). ) = 0.62. Further, the axial pitch of the balls 103 may not be the center of the axial direction, and the axial pitch of the balls 103 may be shifted in the axial direction in order to secure the distance between the application points of the moment and the moment of attachment of the seal and the cage. Good.

FIG. 6 shows a combination of two rows of angular ball bearings 100 each having an annular seal body 104 mounted at one end in the axial direction.
After the angular ball bearings 100 having the annular seal body 104 mounted on one end in the axial direction are combined in two rows and attached to a machine or the like (combined with the seal mounting surface facing outward), the external ball bearing 100 is in use. It is possible to prevent entry of foreign matter, dust, etc. and leakage of the enclosed grease to the outside. In this embodiment, the annular seal body 104 is a non-contact type (non-contact with the inner ring 102) which is inserted into the seal groove 104a of the outer ring 101 and is a reinforcement type rubber seal (for example, nitrile rubber, acrylic rubber). , Fluoro rubber, etc.) 106, and an annular seal body 104 is attached only on the side opposite to the combined end face to save space.

FIG. 7 shows an angular ball bearing 100 in which annular seal bodies 104 are mounted at both ends in the axial direction.
After the angular ball bearing 100 with the annular seal body 104 mounted on both ends in the axial direction is attached to a machine or the like, it prevents foreign matter and dust from entering from outside during use of the bearing, Even when it is assembled into the housing, it is possible to prevent intrusion of foreign matter, dust, etc. and leakage of the enclosed grease to the outside. As for the combination, in order to increase the moment stiffness in two rows, it is desirable to adopt a backside combination (the contact angle is in the direction of the letter C in FIG. 3 and the like) that allows the moment action point distance to be increased. .

If further rigidity is required, as shown in FIGS. 8 and 9, a multi-row combination of three or more rows may be used. For some reason (for example, misalignment is unavoidable when the bearing is installed, the internal load of the bearing is For example, when it is desired to suppress the load as much as possible and to reduce the moment rigidity, an arrangement such as a frontal combination (the contact angle direction is reverse C) may be used as shown in FIG.
Furthermore, in order to load a moment load or an axial load in both directions, it is necessary to use two or more rows of combined bearings. You can use it.

  In this embodiment, the angular ball bearing is used, but other ball bearings such as a deep groove ball bearing may be used. The annular seal body is not the non-contact type shown in FIGS. 6 and 7, but may be a contact type metal core reinforced rubber seal (the rubber material is, for example, nitrile rubber, acrylic rubber, fluoro rubber, etc.), or the outer ring A metal shield plate that is caulked in the seal groove 101 may be used. Further, the annular seal body may be inserted by being inserted into the seal groove on the inner ring 102 side, or may be attached by caulking (a structure in contact with or non-contact with the outer ring).

The material of the inner ring 102, the outer ring 101, and the ball 103 is a bearing steel (eg, SUJ2, SUJ3, etc.) under standard use conditions, but depending on the use environment, for example, a stainless steel that is a corrosion-resistant material in vacuum applications. Materials (for example, martensitic stainless steel materials such as SUS440C, austenitic stainless steel materials such as SUS304, precipitation hardening stainless steel materials such as SUS630, etc.), titanium alloys and ceramic materials (for example, Si ₃ N ₄ , SiC, Al ₂₎ O ₃ , ZrO _2, etc.) may be employed.

The lubrication method is not particularly limited, and mineral oil grease or synthetic oil grease (for example, lithium or urea) or oil can be used in general usage environments, and fluorine grease or fluorine grease for vacuum applications. Or a solid lubricant such as fluorine resin or MoS ₂ can be used.
FIG. 11 shows an angular contact ball bearing provided with an annular seal body 104 at one end in the axial direction (end opposite to the end face on the combination side) and a cage 110 that holds the ball 103 in a rollable manner. 100 is a combination of two rows on the back.

  As the cage 110, for example, as shown in FIGS. 12 to 15 (a), an annular portion 111 and one end portion of the annular portion 111 project in the axial direction at a plurality of locations at substantially equal intervals in the circumferential direction. A flexible crown-shaped cage including the pillars 112 and pockets 113 formed between the pillars 112 to hold the balls 103 so as to roll in the circumferential direction is employed. The material of the cage 110 is, for example, a synthetic resin material such as polyamide, polyacetal, or polyphenylene sulfide, and a material in which a reinforcing material such as glass fiber or carbon fiber is mixed into the synthetic resin material is used as necessary.

In this embodiment, in order to increase the load capacity and rigidity of the bearing, the circumferential pitch between adjacent balls 103 is made as small as possible, and the number of balls is increased as much as possible. Further, the pitch of the balls 103 in the axial direction is shifted as much as possible to the opposite side of the end face on the combination side (see FIG. 11: X ₁ > X ₂ ), and the annular portion 111 of the cage 110 is arranged on the end face side of the bearing combination. Therefore, the distance between the operating points for increasing the moment rigidity can be increased.

In the case of a full ball bearing, the axial pitch of the balls is not the center of the width in the same way as necessary, such as whether or not an annular seal body is mounted. It may be shifted to the opposite side.
When bearings with cages are used with full-ball bearings under conditions that tend to cause variations in revolution speed due to changes in contact angle of each ball, such as continuous rotation in one direction or a large moment load. It is more effective in terms of low torque, low heat generation, etc.

Furthermore, in this embodiment, if the entrance portion of the pocket portion 113 is slightly smaller than the ball diameter and is provided with a hook (pachin allowance), the ball 103 can be assembled without being dropped when the inner ring 102 and the outer ring 101 are assembled. Easy.
The shape of the cage is not limited to this embodiment, and any system other than the separator type cage disposed between the balls 103 may be used. Also, the material may be a metal material instead of a synthetic resin material.

15 (b) is a crown-shaped cage having the same basic structure as FIG. 15 (a), but the pocket portion 113 adjacent to each other at least at one place in the circumferential direction of the annular portion 111 is cut in advance. And it is set as the structure which gave the predetermined clearance gap between each cut surface.
By adopting such a structure, the rolling element pitch circle diameter and the cage pitch circle diameter have shifted due to differences in the thermal expansion coefficient between the cage and the raceway and variations in the dimensional accuracy and roundness of the cage. Even in this case, the ball 103 and the pocket have both the flexibility in the radial direction due to the cantilever shape and the elastic deformation in the circumferential direction (the flexibility in the circumferential direction) due to the gaps between the cut surfaces. The tension force between the portions 113 can be buffered to prevent the cage from being damaged and worn, and torque unevenness and heat generation due to sliding contact resistance between the balls 103 and the pocket portions 113 can be further reduced.

  In addition, since the ball bearing of the present invention has a structurally small ball diameter, the radial thickness of the annular portion 111 of the cage cannot be increased (as can be understood from FIG. 11, the cage is an inner ring). It is necessary to position the gap between the outer diameter and the inner diameter of the outer ring by providing an appropriate gap, and the gap between the outer diameter of the inner ring and the inner diameter of the outer ring is substantially proportional to the ball diameter and is narrow) Furthermore, due to the narrow structure, the gap in the axial direction is also narrow and the axial thickness has to be reduced. For this reason, since the annular portion of the cage is extremely smaller than a standard size bearing and it is difficult to obtain dimensional accuracy such as roundness, the cage structure having the annular portion 111 as shown in FIG. In particular, an effect is obtained with respect to the above-described cage damage and wear prevention effect, and torque unevenness and reduction of heat generation.

Also, the intended application is when the dmn value of the bearing (dm: product of rolling element pitch circle diameter (mm) of rolling bearing and n: rotational speed (min ⁻¹ )) is 200,000 to 300,000 or less at most. In many cases, when the present invention is applied to these uses, even if the cage structure as shown in FIG. If necessary, the circular portion 111 may have two or more cut portions in the circumferential direction. In this case, it is desirable that the cut portions are equally divided in the circumferential direction as much as possible. In addition, when applying a direct drive motor using these bearings to a robot, etc., it is usually used with a preload to increase rigidity, but it is used depending on conditions or for other purposes. May be.

Next, with reference to FIG. 16, the double row ball bearing which is an example of the 2nd Embodiment of this invention is demonstrated.
In this double row full ball angular contact ball bearing 200, a large number of balls 203 are arranged between the double row raceway grooves 201a and 201b of the outer ring 201 and the double row raceway grooves 202a and 202b of the inner ring 202 so as to roll freely. The cross-sectional dimension ratio (B2 / H2) between the cross-sectional width B2 and the radial cross-sectional height H2 (= (outer ring outer diameter D2—inner ring inner diameter d2) / 2) is (B2 / H2) <1.2. The ball pitch circle diameter is set at the center of the radial section height.
Here, in this embodiment, a case where the double row ball bearing 200 is replaced with a double row angular contact ball bearing of 7208A (contact angle 30 °) is taken as an example.

  7208A has an inner ring inner diameter φ40 mm, an outer ring outer diameter φ80 mm, and an axial sectional width (bearing single body width) B of 18 mm, so the sectional dimension ratio (B / H) = 0.9. Therefore, in the angular ball bearing 200 of the present embodiment, the cross-sectional dimension ratio (B2 / H2) = 0.90 (the inner ring inner diameter and the outer ring outer diameter remain the same, and the axial sectional width (bearing unit width) B2 is 18 mm). It is said. As a result, it is possible to receive radial load and moment load, as well as axial load in both directions, as well as space saving by 1/2 in the axial dimension, lower torque and higher rigidity. Can be achieved.

Of course, if necessary, the cross-sectional dimension ratio (B2 / H2) may be set to be less than 0.90 or more than 0.90 (provided that (B2 / H2) <1.2). Incidentally, the contact angle of the angular ball bearing 200 is, for example, 30 °. 17 shows an example in which the ball pitch circle diameter is shifted to the outer ring side in the double row full ball angular contact ball bearing 200 in order to increase the moment rigidity, and FIG. 18 shows each row in the double row full ball angular contact ball bearing 200. 19 is an example in which the ball diameter and the ball pitch circle diameter are changed. FIG. 19 is a double row full-ball angular contact ball bearing 200 in which the annular seal body 104 is mounted at both ends in the axial direction. This is an example in which the diameter of the circle is shifted to the outer ring side.
In any case, in addition to the structure of the annular seal body, the cage, etc., whether or not it is mounted, application examples related to the structure are the same as those of the single row ball bearing described in the first embodiment. Moreover, you may use on any conditions of a preload and a clearance gap like the said 1st Embodiment.

It is a fragmentary sectional view showing a schematic structure of a direct drive motor concerning one embodiment of the present invention. It is sectional drawing which shows a part of single row ball bearing which comprises a two-row combination ball bearing. FIG. 2 is a cross-sectional view showing an embodiment of a rotor support bearing in the direct drive motor of FIG. 1. It is sectional drawing which shows the double row combination ball bearing at the time of shifting the pitch circle diameter of a ball | bowl to the outer ring | wheel side. It is a figure which shows the Example at the time of comprising the rotor support bearing of a direct drive motor with two single row ball bearings from which the pitch circle diameters of a ball differ. It is a figure which shows the Example at the time of comprising the rotor support bearing of a direct drive motor with two single row ball bearings which have an annular seal body. It is a figure which shows the Example at the time of comprising the rotor support bearing of a direct drive motor with one single row ball bearing which has an annular seal body. It is a figure which shows the Example at the time of comprising the rotor support bearing of a direct drive motor combining three single row ball bearings. It is a figure which shows the Example at the time of comprising the rotor support bearing of a direct drive motor combining four single row ball bearings. It is a figure which shows the Example at the time of using the single row ball bearing of FIG. It is a figure which shows the Example at the time of comprising the rotor support bearing of a direct drive motor with the two single row ball bearings which have a holder | retainer. It is sectional drawing of the crown shaped holder | retainer shown in FIG. It is a perspective view which shows a part of crown-shaped holder | retainer shown in FIG. It is the figure which looked at the crown-shaped cage of FIG. 12 from the arrow B direction in the figure. (A) is the figure which looked at the crown shaped holder | retainer of FIG. 12 from the arrow A direction in the figure, (b) is a figure which shows the modification of (a). It is a figure which shows the Example at the time of comprising the rotor support bearing of a direct drive motor with a double row ball bearing. It is sectional drawing which shows the double row ball bearing at the time of shifting the pitch circle diameter of a ball | bowl to the outer ring | wheel side. It is a figure which shows the modification of the Example shown in FIG. It is a figure which shows the Example at the time of comprising the rotor support bearing of a direct drive motor with the double row ball bearing which has an annular seal body. It is explanatory drawing for demonstrating the deformation amount of the radial direction of an inner ring | wheel. It is explanatory drawing for demonstrating the calculation method of the cross-sectional secondary moment of an inner ring | wheel. It is a graph which shows the relationship between a cross-sectional dimension ratio (B / H) and the deformation amount of the bearing ring of radial direction. It is a graph which shows the relationship between a cross-sectional dimension ratio (B / H) and a cross-sectional secondary moment I. It is a graph which shows the relationship between a cross-sectional dimension ratio (B / H) and the deformation amount of the bearing ring of radial direction. It is a graph which shows the relationship between a cross-sectional dimension ratio (B / H) and a cross-sectional secondary moment I. It is a graph which shows the comparison of the calculated moment rigidity in various bearings. It is sectional drawing which shows a part of cross roller bearing. It is sectional drawing which shows a part of two-row combination angular contact ball bearing. It is sectional drawing which shows a part of double row combination angular contact ball bearing which combines the single row angular contact ball bearing of an ultra-thin section in two rows. It is a fragmentary sectional view which shows schematic structure of the conventional direct drive motor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Stator 11a Stator core 11b Stator coil 12 Rotor 12a Rotor core 12b Rotor magnet 13 Rolling bearing 14 Pulsar ring 15 Position detector 16 Rotor support bearing 100 Single row ball bearing 101 Outer ring 101a Outer ring raceway groove 102 Inner ring raceway 103 Ball 104 Annular seal body 110 Cage

Claims (4)

  A rotor, a stator disposed inside or outside the rotor, and a rolling bearing that rotatably supports the rotor with respect to the stator, and directly loading a load without using a reduction gear. In the direct drive motor that drives the inner ring, the rolling bearing includes an inner ring, an outer ring disposed on the outer periphery of the inner ring, and a plurality of balls that are rotatably incorporated between the inner ring and the outer ring. A direct drive comprising a row of ball bearings, wherein a sectional dimension ratio (B / H) between an axial sectional width B and a radial sectional height H is (B / H) <0.63 motor.   It consists of a single-row ball bearing having an inner ring, an outer ring disposed on the outer periphery of the inner ring, and a plurality of balls that are rotatably incorporated between the inner ring and the outer ring, without using a reduction gear. A direct drive motor bearing that rotatably supports a rotor of a direct drive motor that directly drives a load, wherein a cross-sectional dimension ratio between an axial sectional width B and a radial sectional height H of the ball bearing ( (B / H) is (B / H) <0.63.   A rotor, a stator disposed inside or outside the rotor, and a rolling bearing that rotatably supports the rotor with respect to the stator, and directly loading a load without using a reduction gear. In the direct drive motor that drives the inner ring, the rolling bearing includes an inner ring, an outer ring disposed on an outer periphery of the inner ring, and a plurality of balls that are rotatably incorporated between the inner ring and the outer ring. A direct drive motor having a cross-sectional dimension ratio (B2 / H2) between the axial sectional width B2 and the radial sectional height H2 is (B2 / H2) <1.2. .   A double-row ball bearing having an inner ring, an outer ring disposed on the outer periphery of the inner ring, and a plurality of balls that are rotatably incorporated between the inner ring and the outer ring. A direct drive motor bearing that rotatably supports a rotor of a direct drive motor that directly drives the cross-sectional dimension ratio between the axial sectional width B2 and the radial sectional height H2 of the double row ball bearing A bearing for a direct drive motor, wherein (B2 / H2) is (B2 / H2) <1.2.

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