JP2018044646A - Ball bearing, bearing unit for dental air turbine, and dental air turbine handpiece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ball bearing capable of preventing occurrence of abrasion of a ball and suppressing deterioration of a rotational speed of a dental air turbine for a long period, and also provide a bearing unit for a dental air turbine, and a dental air turbine handpiece.SOLUTION: A ball bearing 100 includes: a pair of raceway rings; a main raceway surface 15 and a sub raceway surface 17 provided at one of the pair of raceway rings; a single row raceway surface 19 provided at the other of the pair of raceway rings; a plurality of main balls 21 arranged between the main raceway surface 15 and the single row raceway surface 19 in a rollable manner; and a plurality of sub balls 23 arranged between the main balls 21, and contacting with a pair of adjacent main balls 21 and the sub raceway surface 17. The sub raceway surface 17 is arranged on an anti-preload side to the main raceway surface 15, and has a groove depth deeper than a groove depth of the main raceway surface 15.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a ball bearing, a dental air turbine bearing unit, and a dental air turbine handpiece.

  In general, a full ball bearing is known as one of rolling bearings for high-speed rotation. This ball bearing is also employed in, for example, a dental handpiece disclosed in Patent Document 1 and a spindle motor disclosed in Patent Document 2, and supports a shaft that rotates at high speed. The ball bearings of Patent Documents 1 and 2 both have a single-row raceway surface on the inner and outer rings, and the ball diameter is a single diameter.

JP-A-1-223951 JP 2003-172359 A

  However, since conventional ball bearings used in dental air turbines are used at a high rotational speed of 300,000 to 500,000 revolutions / minute, a slight difference in the revolution speed of each ball occurs due to a slight decrease in ball accuracy. . When the revolution speed difference increases, the surfaces of adjacent balls may collide while rotating in the opposite direction. In that case, even if ceramic balls with improved wear resistance are used as balls of the ball bearing, the ceramic balls are worn, the balls are evenly distributed, and the rotational speed of the dental air turbine is likely to decrease. It was causing the problem.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above situation, and its object is to provide a ball bearing, a dental air turbine bearing unit and a dental air turbine bearing unit that are less likely to cause ball wear and that can suppress a decrease in rotational speed of the dental air turbine over a long period of time. It is to provide a dental air turbine handpiece.

The above object of the present invention is achieved by the following configuration.
(1) a pair of race rings,
A main raceway surface and a sub raceway surface provided on any one of the pair of raceways,
A single row raceway surface provided on the other of the pair of raceways,
A plurality of main balls arranged to roll freely between the main raceway surface and the single row raceway surface;
A plurality of secondary balls arranged between the primary balls and in contact with a pair of adjacent primary balls and the secondary track surface;
Comprising
The main ball has a contact angle and is disposed between the main raceway surface and the single row raceway surface,
The secondary raceway surface is a ball bearing that is disposed on the anti-preload side with respect to the main raceway surface and has a groove depth deeper than the groove depth of the main raceway surface.
(2) a rotating shaft;
A turbine blade provided on the rotating shaft and configured to rotationally drive the rotating shaft with compressed air;
The ball bearing for rotatably supporting the rotating shaft;
A housing that supports the rotating shaft via the ball bearing;
A dental air turbine bearing unit comprising:
(3) A dental air turbine handpiece comprising the dental air turbine bearing unit of (2).

  According to the present invention, it is possible to make ball wear less likely to occur than before. Moreover, the equal distribution of the balls can be maintained, and a reduction in the rotational speed of the dental air turbine can be suppressed over a long period of time.

It is a front view of the ball bearing of the 1st example of composition. It is the perspective view which notched a part of ball bearing shown in FIG. It is sectional drawing which shows the internal peripheral surface of the outer ring | wheel shown in FIG. It is the side view which notched a part of inner ring shown in FIG. It is a principal part enlarged view of the ball bearing of the 1st example of composition. It is a principal part enlarged front view of the ball bearing of the 1st example of composition. It is a front view of the ball bearing of the 2nd example of composition. It is the perspective view which notched a part of outer ring of the ball bearing shown in FIG. It is a side view of the outer ring | wheel shown in FIG. It is the side view which notched a part of inner ring shown in FIG. It is the perspective view which notched a part of ball bearing of the example of the 3rd composition. It is the side view which notched a part of outer ring shown in FIG. It is a modification of the ball bearing of the 3rd example of composition, and is a side view which notched a part of outer ring. It is a ball bearing of the 4th example of composition, and is a side view which notched a part of ball bearing. It is a ball bearing of the 5th example of composition, and is a side view which notched a part of ball bearing. 1 is a schematic side view showing a general dental air turbine handpiece. It is an expanded sectional view of the head part of a dental air turbine handpiece.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First configuration example)
FIG. 1 is a front view of a ball bearing 100 of a first configuration example, and FIG. 2 is a perspective view in which a part of the ball bearing 100 shown in FIG.
As shown in FIG. 1, the ball bearing 100 of this configuration example includes an inner ring 11 and an outer ring 13, which are a pair of race rings, a plurality of main balls 21, and a plurality of sub balls 23. The main ball 21 is a large-diameter ball, and the secondary ball 23 is a small-diameter ball having a smaller diameter than the main ball 21.

  As shown in FIG. 2, the ball bearing 100 is provided with a main raceway surface 15 serving as a raceway surface of the main ball 21 and a sub raceway surface 17 serving as a raceway surface of the secondary ball 23 on the inner peripheral surface of the outer ring 13. Further, a single row raceway surface 19 serving as a raceway surface of the main ball 21 is provided on the outer peripheral surface of the inner ring 11.

  A plurality of main balls 21 are arranged in the circumferential direction between the main raceway surface 15 and the single row raceway surface 19. The secondary balls 23 are disposed between the primary balls 21 and are equally distributed in the circumferential direction in contact with the adjacent primary balls 21 and the secondary track surface 17. Therefore, the secondary balls 23 and the main balls 21 are alternately arranged along the circumferential direction.

  That is, in the ball bearing 100, the main ball 21 and the sub ball 23 are equally arranged in the circumferential direction, and the axial center position of the main ball 21 and the axial center position of the sub ball 23 are in one axial direction. They are shifted.

FIG. 3 is a cross-sectional view showing the inner peripheral surface of the outer ring 13 shown in FIG. 2, and FIG. 4 is a side view of the inner ring 11 shown in FIG.
As shown in FIG. 3, two raceways are provided on the inner circumferential surface of the outer ring 13, a main raceway surface 15 that is a raceway surface of the main ball 21 and a sub raceway surface 17 that is a raceway surface of the secondary ball 23. It is done. In this configuration example, the main track surface 15 and the sub track surface 17 are formed adjacent to each other in the axial direction, and the groove depth of the sub track surface 17 is larger than the groove depth of the main track surface 15 in the radial direction. It is deeper.

  On the other hand, as shown in FIG. 4, only the single-row raceway surface 19 that is the raceway surface of the main ball 21 is provided on the outer circumferential surface of the inner ring 11. The inner ring 11 has a shoulder portion 25 formed on one side in the axial direction and a counter bore 27 formed on the other side in the axial direction at the outer peripheral portion thereof. Thereby, the ball bearing 100 is arranged between the main raceway surface 15 and the single row raceway surface 19 with the main ball 21 having a contact angle, and constitutes an angular contact bearing of an inner ring counter. Further, the secondary raceway surface 17 of the outer ring 13 is disposed on the counter-preload side that is downstream in the preload direction with respect to the main raceway surface 15.

FIG. 5 is an enlarged view of the main part of the ball bearing of the first configuration example, and FIG. 6 is an enlarged front view of the main part of the ball bearing of the first configuration example.
The ball bearing 100 employs a secondary ball 23 having a diameter larger than the circumferential interval between the main balls 21 when the main balls 21 are equally arranged. Further, the secondary ball 23 has an appropriate clearance in a space inside three points of the contact point Pa with the secondary raceway surface 17 of the outer ring 13 and the contact points Pb and Pc with a pair of adjacent main balls 21. It is settled. Thereby, the secondary ball 23 does not jump out from between the main balls 21 in the axial direction.

Next, the operation of the above configuration will be described.
In the ball bearing 100 of this configuration, a plurality of main balls 21 are disposed between the main raceway surface 15 of the outer ring 13 and the single row raceway surface 19 of the inner ring 11, and the inner ring 11 and the outer ring 13 are interposed via the main ball 21. Rotates relative to each other. Further, the secondary ball 23 is disposed in contact with the main ball 21 and the secondary raceway surface 17.

  One auxiliary ball 23 is disposed between adjacent main balls 21, and contacts the pair of adjacent main balls 21 and the sub track surface 17 at three contact points Pa, Pb, Pc. Thereby, the secondary ball 23 is stably disposed in the bearing without dropping from the space between the pair of main balls 21 and the secondary raceway surface 17. Further, the main ball 21 is disposed between the secondary balls 23 so that the main balls do not directly contact each other.

  As shown in FIG. 6, when the main balls 21 are viewed from the direction along the axis, the inner ring 11 and the outer ring 13 relatively rotate (in the illustrated example, the inner ring 11 rotates counterclockwise) It rotates in the same direction (clockwise in the illustrated example). The secondary ball 23 sandwiched between a pair of main balls 21 that rotate in the same direction receives the rotation of the main ball 21 from the contacts Pb and Pc, and rotates counterclockwise. Therefore, the contact points Pb and Pc between the main ball 21 and the secondary ball 23 are in contact with each other in the forward direction, and the surfaces do not contact while rotating in the reverse direction.

  By the way, the secondary ball 23 comes into contact with the secondary raceway surface 17 while rotating in the reverse direction at the contact point Pa with the secondary raceway surface 17. However, since the contact point Pa between the secondary ball 23 and the secondary raceway surface 17 does not directly receive the axial load in the radial direction, the secondary ball 23 and the secondary raceway surface 17 are greatly worn even when they are in contact with each other. There is nothing.

  Thus, in the ball bearing 100 of this configuration, the plurality of main balls 21 that are in rolling contact with the inner ring 11 and the outer ring 13 have the sub balls 23 interposed between a pair of adjacent main balls 21. Therefore, unlike the conventional full ball bearing, the ball surfaces do not collide while rotating in opposite directions. Moreover, since the preload is not applied to the secondary ball 23, the secondary ball 23 is in a free support state. Therefore, the main ball 21, the secondary ball 23, the main raceway surface 15, the secondary raceway surface 17, and the single row raceway surface 19 are less likely to be worn.

  Further, in the ball bearing 100 of this configuration, since the radial groove depth of the secondary raceway surface 17 is deeper than the radial groove depth of the main raceway surface 15, the rolling contact with respect to the entire circumference of the surface of the secondary ball 23. The ratio of the circumference of the surface is larger than that of the main ball 21. Therefore, the secondary ball 23 is less likely to be detached from the secondary raceway surface 17, and the main ball 21 is also less likely to be detached from the primary raceway surface 15 and the single row raceway surface 19. Therefore, it is possible to more reliably prevent the main ball 21 and the secondary ball 23 from falling out of the bearing.

  Further, since both the main raceway surface 15 and the sub raceway surface 17 of the outer ring 13 are grooves that are recessed in the radial direction, it is possible to continuously process the double-row raceway surface grooves with the same tool, thereby improving workability and processing accuracy. .

  Further, in the ball bearing 100 of this configuration, the center of the secondary ball 23 is shifted in one axial direction with respect to the center of the main ball 21, but the center of the secondary ball 23 and the center of the main ball 21 are axial. May be arranged to match. In that case, the width of the ball bearing 100 can be reduced.

  The ball bearing 100 has a shoulder 25 formed on one side in the axial direction of the inner ring 11 and a counter bore 27 formed on the other side in the axial direction. For this reason, the main ball 21 can increase the contact angle and increase the load capacity of the axial load of the bearing.

  In the ball bearing 100 of this configuration, the secondary ball 23 has a smaller diameter than the main ball 21, but may have the same diameter.

(Second configuration example)
Next, the ball bearing 200 of the second configuration example will be described. In the following description, the same or equivalent parts as those in the first configuration example are denoted by the same reference numerals, and the description thereof is omitted or simplified.

FIG. 7 is a front view of the ball bearing 200 of the second configuration example, and FIG. 8 is a perspective view in which a part of the outer ring 29 of the ball bearing 200 shown in FIG. 9 is a side view of the outer ring 29 shown in FIG. 8, and FIG. 10 is a side view of the inner ring 31 shown in FIG.
The ball bearing 200 of this configuration has a configuration in which the main raceway surface 15 and the secondary raceway surface 17 are provided on the inner ring 31 and the single row raceway surface 19 is provided on the outer ring 29.
The plurality of main balls 21 are equally distributed in the circumferential direction between the main raceway surface 15 of the inner ring 31 and the single row raceway surface 19 of the outer ring 29, and the sub-balls 23 are arranged between the main balls 21. The The plurality of secondary balls 23 are equally arranged in the circumferential direction along the secondary track surface 17. The secondary ball 23 is arranged so as to be shifted to one side in the axial direction with respect to the center of the main ball 21.

  As described above, the single row raceway surface 19 provided on the inner periphery of the outer ring 29 shown in FIG. 9 and the main raceway surface 15 provided on the outer periphery of the inner ring 31 shown in FIG. Become. Further, the secondary raceway surface 17 of the inner ring 31 becomes the raceway surface of the secondary ball 23. The main raceway surface 15 and the secondary raceway surface 17 of this configuration are formed adjacent to the outer peripheral surface of the inner ring 31 in the axial direction, and the groove depth of the secondary raceway surface 17 is the groove of the main raceway surface 15 in the radial direction. It is deeper than the depth.

  The outer ring 29 has a shoulder portion 25 formed on one side in the axial direction and a counter bore 27 formed on the other side in the axial direction on the inner peripheral surface thereof. Thus, the ball bearing 200 constitutes an angular contact bearing of an outer ring counter in which the main ball 21 has a contact angle and is disposed between the main raceway surface 15 and the single row raceway surface 19. Further, the secondary raceway surface 17 is disposed on the counter-preload side with respect to the main raceway surface 15.

  In the ball bearing 200 of the present configuration, as shown in FIG. 8, the secondary ball 23 includes the secondary raceway surface 17 of the inner ring 31 and the insides of the three contacts Pa, Pb, Pc between the pair of adjacent main balls 21. It fits in the space with proper clearance. This ball bearing 200 employs the secondary balls 23 that are larger than the interval when the primary balls 21 are equally arranged, so that the secondary balls 23 do not jump out in the axial direction from between the primary balls.

  Further, since the groove depth in the radial direction of the secondary raceway surface 17 is deeper than the radial groove depth of the main raceway surface 15, the secondary ball 23 is difficult to come off from the secondary raceway surface 17. Therefore, it is possible to more reliably prevent the main ball 21 and the secondary ball 23 from falling out of the bearing.

  Further, according to the ball bearing 200 of this configuration, no preload is applied to the secondary ball 23, and the centrifugal force acting on the secondary ball 23 and the secondary raceway surface 17 is reduced as compared with the case of the first configuration example. Wear can be made difficult to occur. In addition, the same effects as the ball bearing 100 of the first configuration example can be obtained.

(Third configuration example)
Next, the ball bearing 300 of the third configuration example will be described.
11 is a perspective view in which a part of the ball bearing 300 of the third configuration example is cut out, and FIG. 12 is a side view in which a part of the outer ring shown in FIG. 11 is cut out.

  In the ball bearing 300 of this configuration, a main raceway surface 15 serving as a starting surface of the main ball 21 and a pair of sub raceway surfaces 17A and 17B are provided on both sides of the main raceway surface 15 on the inner peripheral surface of the outer ring 35. . Thereby, the secondary ball | bowl 23 adjacent to the main ball | bowl 21 is alternately shifted | deviated and arrange | positioned along the circumferential direction at one side and the other of an axial direction. The inner ring 33 has the same configuration as that of the inner ring 11 of the first configuration example shown in FIG. 4, and a single row raceway surface 19 serving as a raceway surface of the main ball 21 is provided on the outer circumferential surface of the inner ring 33. The outer ring 35 is formed such that the outer ring groove shoulder 36 on the side without the groove shoulder of the inner ring 33 is formed thick, thereby preventing the secondary ball 23 from falling off.

  In the ball bearing 300 of this configuration, the secondary balls 23 arranged between the plurality of main balls 21 have a staggered arrangement in which the main balls 21 are alternately arranged on one side and the other side in the axial direction. .

  According to this ball bearing 300, the secondary balls 23 are alternately arranged on the opposite side in the axial direction across the main ball 21, so that both sides sandwiching the center of the main ball 21 can be brought into contact with the secondary ball 23, The rotation balance of the main ball 21 is stabilized. Further, since the preload is not applied to the secondary ball 23 that rolls on the secondary raceway surface 17B, the secondary ball 23 is less likely to be worn.

  Further, in the ball bearing 300 of this configuration, since the radial groove depth of the secondary raceway surface 17B is deeper than the radial groove depth of the main raceway surface 15, the secondary ball 23 is difficult to come off from the secondary raceway surface 17B. . Therefore, it is possible to more reliably prevent the main ball 21 and the secondary ball 23 from falling out of the bearing.

  In addition to this configuration, the main raceway surface 15 and the secondary raceway surfaces 17A and 17B may be provided on the inner ring 33 and the single row raceway surface 19 may be provided on the outer ring 35.

  Further, as shown in FIG. 13, the ball bearing 300 may have a configuration in which a pair of secondary balls 23 and 23 are arranged in the same phase in the axial direction between adjacent main balls 21.

  In this case, since the main ball 21 contacts the secondary balls 23 and 23 symmetrically in the bearing width direction, the main ball 21 rolls more stably. In addition, the contact points of the main ball 21 and the secondary balls 23 and 23 rotate in the forward direction, so that the surfaces do not contact while rotating in the reverse direction.

(Fourth configuration example)
Next, the ball bearing 400 of the fourth configuration example will be described.
FIG. 14 is a side view of the ball bearing 400 of the fourth configuration example, with a part of the ball bearing 400 cut away.
In the ball bearing 400 of this configuration, the inner ring 39 is formed integrally with the inner ring 39 and has an annular sealing portion 37 extending outward in the radial direction. Further, the outer ring 41 has an annular sealing portion 38 that is formed integrally with the outer ring 41 and extends radially inward. In addition, a single row raceway surface 19 is formed on the inner ring 39, and a main raceway surface 15 and a sub raceway surface 17 are formed on the outer ring 41.

  The ball bearing 400 has a shoulder portion 25 on one side in the axial direction of the inner ring 39 and a counter bore 27 on the other side in the axial direction. That is, the ball bearing 400 becomes an angular contact bearing of the inner ring counter. Further, the secondary track surface 17 is disposed on the side opposite to the preload side with respect to the main track surface 15, and the groove depth of the secondary track surface 17 is deeper than the groove depth of the main track surface 15 in the radial direction.

  According to the ball bearing 400 having the above-described configuration, the inner ring 39 and the outer ring 41 have the integrally formed sealing portions 37 and 38, so that the inner ring outer peripheral surface and the inner ring inner ring can be formed without using a separate seal member. Covering the axial end opening with the peripheral surface, it is possible to suppress the entry of foreign matter into the bearing. Therefore, only a small number of parts are required, and an attachment structure for attaching a separate seal member is not required. Therefore, the shapes of the inner ring 39 and the outer ring 41 can be simplified. In addition, the same effects as the ball bearing 100 of the first configuration example can be obtained.

(Fifth configuration example)
Next, the ball bearing 500 of the fifth configuration example will be described.
FIG. 15 is a side view of the ball bearing 500 of the fifth configuration example, with a part of the ball bearing 500 cut away.
In the ball bearing 500 of this configuration, the inner ring 43 is formed integrally with the inner ring 43 and has an annular sealing portion 37 that extends radially outward. Further, the outer ring 45 includes an annular sealing portion 38 that is formed integrally with the outer ring 45 and extends radially inward. In addition, a single row raceway surface 19 is formed on the outer ring 45, and a main raceway surface 15 and a sub raceway surface 17 are formed on the inner ring 43.

  This ball bearing 500 has a shoulder portion 25 on one side in the axial direction of the outer ring 45 and a counter bore 27 on the other side in the axial direction. That is, the ball bearing 500 serves as an angular contact bearing for the outer ring counter. Further, the secondary track surface 17 is disposed on the side opposite to the preload side with respect to the main track surface 15, and the groove depth of the secondary track surface 17 is deeper than the groove depth of the main track surface 15 in the radial direction.

  According to the ball bearing 500 having the above configuration, the same operational effects as those of the ball bearing 400 of the fourth configuration example can be obtained.

(Sixth configuration example)
Next, the case where the ball bearing of each structure demonstrated above is applied to a dental air turbine is demonstrated. Here, an example in which the ball bearing 100 of the first configuration example is applied to a dental air turbine will be described as an example.

FIG. 16 is a schematic side view showing a general dental air turbine handpiece 47.
The dental air turbine handpiece 47 includes a grip portion 49 and a head portion 51 provided at the distal end portion of the grip portion 49, and an operator performs cutting of teeth, for example, with the grip portion 49.

FIG. 17 is an enlarged cross-sectional view of the head portion 51 of the dental air turbine handpiece 47.
The dental air turbine bearing unit 55 constituting the head portion 51 includes a rotating shaft 57 to which a dental treatment tool (not shown) is attached, a turbine blade 59 provided on the rotating shaft 57 and rotationally driving the rotating shaft 57 with compressed air. And a pair of ball bearings 100A and 100B that rotatably support the rotating shaft 57, and a housing 61 that supports the rotating shaft 57 via the ball bearings 100A and 100B.

  The pair of ball bearings 100A and 100B have the same configuration as the ball bearing of the first configuration example described above. The outer rings 13 of the ball bearings 100 </ b> A and 100 </ b> B are supported via a rubber ring 65 attached to the annular recess 63 of the housing 61. The outer ring 13 of the lower ball bearing 100B is urged upward by a spring washer 67, and a preload is applied to the pair of ball bearings 100A and 100B. That is, the pair of ball bearings 100 </ b> A and 100 </ b> B that support the rotating shaft 57 are combined in front and are given a constant pressure preload by the elastic force of the spring washer 67.

  The dental air turbine bearing unit 55 having this configuration uses the above-described ball bearing 100 (or may be the ball bearings 200, 300, 400, 500), so that the surfaces of the main balls rotate in opposite directions. While there is no collision. Thereby, it is hard to generate | occur | produce in the main ball | bowl 21 and it becomes difficult for the equal distribution of the main ball | bowl 21 to collapse. As a result, the rotational speed of the rotating shaft 57 can be maintained high for a long period.

  As described above, the present invention is not limited to the above-described embodiments, and those skilled in the art can make changes and applications based on combinations of the configurations of the embodiments, descriptions in the specification, and well-known techniques. This is also the scope of the present invention, and is included in the scope for which protection is sought.

As described above, the following items are disclosed in this specification.
(1) a pair of race rings,
A main raceway surface and a sub raceway surface provided on any one of the pair of raceways,
A single row raceway surface provided on the other of the pair of raceways,
A plurality of main balls arranged to roll freely between the main raceway surface and the single row raceway surface;
A plurality of secondary balls arranged between the primary balls and in contact with a pair of adjacent primary balls and the secondary track surface;
Comprising
The main ball has a contact angle and is disposed between the main raceway surface and the single row raceway surface,
The secondary raceway surface is a ball bearing that is disposed on the anti-preload side with respect to the main raceway surface and has a groove depth deeper than the groove depth of the main raceway surface.
According to this ball bearing, a plurality of main balls are arranged between the main raceway surface and the single row raceway surface. In addition, the secondary balls are arranged between the main balls, and roll in contact with a pair of adjacent primary balls and the secondary track surface. As a result, the contact points of the main ball and the secondary ball are in contact with each other in the forward direction, and the surfaces do not contact while rotating in the reverse direction. In addition, since the preload is not applied to the secondary ball, the secondary ball is in a free-supporting state, and no major wear occurs on the main ball, secondary ball, and each raceway surface.
In addition, since the radial groove depth of the secondary raceway surface is deeper than the radial groove depth of the primary raceway surface, the secondary ball is less likely to come off from the secondary raceway surface, and the main ball and secondary ball fall off from the bearing. Can be prevented more reliably.
(2) The secondary ball has a smaller diameter than the main ball,
The ball bearing according to (1), wherein the secondary ball and the main ball are alternately arranged along a circumferential direction.
According to this ball bearing, the main ball is disposed between the secondary balls, and the main balls are not in direct contact with each other.
(3) The ball bearing according to (1) or (2), wherein the auxiliary ball is arranged so as to be shifted in an axial direction from a center of the main ball.
According to this ball bearing, the secondary ball is arranged so as to be shifted in the axial direction from the center of the main ball, whereby the number of main balls that can be arranged is increased and the load bearing capacity of the bearing is increased.
(4) Each of the pair of bearing rings is integrally formed with an annular sealing portion that covers an axial end opening between the outer peripheral surface of the inner diameter side raceway ring and the inner peripheral surface of the outer diameter side raceway ring. The formed ball bearing according to any one of (1) to (3).
According to this ball bearing, it is possible to suppress the intrusion of foreign matter into the bearing without newly using a separate seal member and simplifying the shape of each bearing ring.
(5) The ball bearing according to any one of (1) to (4), wherein the secondary raceway surfaces are formed in a double row.
According to this ball bearing, a plurality of secondary balls can be arranged, and the rotation balance of the main ball can be further stabilized.
(6) a rotating shaft;
A turbine blade provided on the rotating shaft and configured to rotationally drive the rotating shaft with compressed air;
The ball bearing according to any one of (1) to (5), which rotatably supports the rotating shaft;
A housing that supports the rotating shaft via the ball bearing;
A dental air turbine bearing unit comprising:
According to this dental air turbine bearing unit, even when the rotary shaft rotates at a high speed, the balls are not evenly distributed due to wear, and the rotational speed is unlikely to decrease.
(7) A dental air turbine handpiece provided with the bearing unit for dental air turbine of (6).
According to this dental air turbine handpiece, an excellent configuration with little deterioration over a long period of time can be achieved.

11, 31, 33, 39, 43 Inner ring (Raceway)
13, 29, 35, 41, 45 Outer ring (Raceway)
DESCRIPTION OF SYMBOLS 15 Main track surface 17,17A, 17B Secondary track surface 19 Single row track surface 21 Main ball 23 Secondary ball 37,38 Sealing part 47 Dental air turbine handpiece 55 Dental air turbine bearing unit 57 Rotary shaft 59 Turbine blade 61 Housing 100 , 200, 300, 400, 500 Ball bearings

Claims (7)

A pair of race rings,
A main raceway surface and a sub raceway surface provided on any one of the pair of raceways,
A single row raceway surface provided on the other of the pair of raceways,
A plurality of main balls arranged to roll freely between the main raceway surface and the single row raceway surface;
A plurality of secondary balls arranged between the primary balls and in contact with a pair of adjacent primary balls and the secondary track surface;
Comprising
The main ball has a contact angle and is disposed between the main raceway surface and the single row raceway surface,
The secondary raceway surface is a ball bearing that is disposed on the anti-preload side with respect to the main raceway surface and has a groove depth deeper than the groove depth of the main raceway surface. The secondary ball is smaller in diameter than the main ball,
The ball bearing according to claim 1, wherein the secondary ball and the main ball are alternately arranged along a circumferential direction.   The ball bearing according to claim 1, wherein the secondary ball is arranged so as to be shifted in an axial direction from a center of the main ball.   The pair of race rings are integrally formed with an annular sealing portion that covers an axial end opening between the outer peripheral surface of the inner diameter side race ring and the inner peripheral surface of the outer diameter side race ring. The ball bearing as described in any one of Claims 1-3.   The ball bearing according to any one of claims 1 to 4, wherein the secondary raceway surface is formed in a double row. A rotation axis;
A turbine blade provided on the rotating shaft and configured to rotationally drive the rotating shaft with compressed air;
The ball bearing according to any one of claims 1 to 5, wherein the rotary shaft is rotatably supported.
A housing that supports the rotating shaft via the ball bearing;
A dental air turbine bearing unit comprising:   A dental air turbine handpiece comprising the dental air turbine bearing unit according to claim 6.

Images