JP2022169195A - Angular ball bearing - Google Patents

Abstract

To provide an angular ball bearing which employs an outer ring guide cage and which can improve the strength of the cage while maintaining the dimensions and fundamental performance of the bearing.SOLUTION: An angular ball bearing 11 comprises inner and outer rings 12, 13, a plurality of balls 14 interposed between the inner and outer rings 12, 13, and a cage 15 for holding the balls 14 in cylindrical pockets Pt which are formed at a plurality of points in a circumferential direction. The cage 15 is of a type of a cage guide for guiding the outer ring. An inside diameter Hd of the cylindrical cage 15 is set to a value which is obtained by subtracting 0.25 to 0.35 times of a diameter Da of the ball 14 from a pitch circle diameter P.C.D. of the ball 14. A wall thickness of the cage 15 in a radial direction is 0.40 to 0.45 times of the diameter Da of the ball 14, and a width of the cage 15 in an axial direction is 1.6 to 2.0 times of the diameter Da of the ball 14 within a range that prevents it from protruding from both ends of the inner ring 12 and the outer ring 13 in the axial direction.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to angular contact ball bearings used, for example, in spindles of machine tools and other equipment.

Angular contact ball bearings are widely used for bearings that support rotating bodies for high-speed operation, including the spindles of machine tools. An outer ring guide retainer or a rolling element guide retainer is often used for the retainer of the angular contact ball bearing. As the retainer, a lightweight resin retainer is often used in order to reduce the influence of centrifugal force. The resin is a resin material such as nylon reinforced with glass fiber or carbon fiber, high melting point polyamide resin, polyether ether ketone resin (abbreviation: PEEK material), phenol resin, etc., and is formed into a cylindrical shape (for example, Patent documents 1-3).

In order to realize high efficiency and space saving of machine tools, it is necessary to increase the rotation speed and improve the load capacity of the angular contact ball bearings that support the spindles of the machine tools. When the bearing rotates at high speed or under high load conditions, the cage is subjected to centrifugal force and an excessive load due to lead/lag of the balls from the balls, so the cage must have sufficient strength.

JP 2011-117542 A JP 2014-95469 A JP 2016-145644 A

The basic performance of angular contact ball bearings depends on the ball diameter and the number of balls, but if the ball diameter is increased or the number of balls is increased, the space available for the cage will become smaller, and the cage will not have sufficient strength. can become difficult to have
In order for the retainer to have sufficient strength, it is necessary to increase the ring thickness, axial width, and pocket spacing of the retainer. However, since the basic performance of a bearing generally depends on the ball diameter and the number of balls, we propose a cage shape that improves the cage strength while ensuring the basic performance of the bearing in the limited space inside the bearing. do.

SUMMARY OF THE INVENTION An object of the present invention is to provide an angular contact ball bearing to which an outer ring guide cage is applied, in which the strength of the cage can be improved while maintaining the dimensions and basic performance of the bearing.

An angular contact ball bearing according to the present invention comprises an inner ring, an outer ring, a plurality of balls interposed between the inner ring and the outer ring, and a retainer for holding the balls in pockets provided at a plurality of locations in the circumferential direction. The angular contact ball bearing, wherein the retainer is of a retainer guide type with an outer ring guide, and the outer peripheral surface of the retainer at a position serving as the outer ring guide surface of the retainer is formed in an axially cylindrical shape,
Let HD be the outside diameter of the cage, Hd be the inside diameter of the cage, and P.D. be the pitch circle diameter of the balls. C. D. When HD-P. C. D. >P. C. D. - satisfies the relationship of Hd,
The inner diameter Hd of the cage is defined by the pitch diameter P.D. of the balls. C. D. A value obtained by subtracting 0.25 to 0.35 times the diameter Da of the ball from
The radial thickness T of the retainer is 0.40 to 0.45 times the diameter Da of the ball.

According to this construction, the inner diameter Hd of the outer ring guide retainer is set to the pitch circle diameter P. C. D. by subtracting 0.25 to 0.35 times the ball diameter Da from the P.D. C. D. to the inner diameter side portion of the retainer pocket. Therefore, a contact ellipse generated by whirling of the cage and contact between the balls and the cage does not contact the inner diameter side edge portion of the pocket of the cage. For example, if the inner diameter Hd of the retainer is P.M. C. D. At −Da×0.20 or less, the contact ellipse contacts the inner diameter edge of the pocket. The inner diameter Hd of the retainer is P.M. C. D. If -Da×0.40 or more, due to the cage wall thickness, the inner ring guides in contact with the inner ring, and the outer ring guide may not be established. If the clearance is relatively narrow, there is a possibility that the outer ring guide will be eliminated or close to it, considering the wear of the outer diameter portion of the retainer during use of the bearing.

Furthermore, the radial thickness T of the retainer is set to 0.40 to 0.45 times the ball diameter Da. As a result, the retainer has sufficient strength against the centrifugal force generated under high-speed operation and high-load conditions or the load generated due to lead/lag of the balls. For example, if the thickness T of the cage is Da×0.35 or less, the cage strength or load bearing performance may be insufficient. If the thickness T of the retainer is Da×0.50 or more, it is impossible due to the structure of the retainer. This is because the radial area of the retainer is restricted to the extent that the shoulders of the inner ring and the shoulders of the outer ring require desired dimensions.
Therefore, in the angular contact ball bearing to which the outer ring guide retainer is applied, the strength of the retainer can be improved while maintaining the dimensions and basic performance of the bearing.

The axial width HB of the retainer may be 1.6 to 2.0 times the diameter Da of the balls within a range that does not protrude from both axial ends of the inner ring and the outer ring of the angular contact ball bearing. There is a limit to enlarging the cage on the inner diameter side in order to improve the cage strength and load bearing performance in the outer ring guide cage. For this reason, the retainer is enlarged by maximally utilizing the axial region within a range that does not protrude from both ends of the inner ring and the outer ring in the axial direction. Further, by extending the retainer in the axial direction, the sliding contact portion between the inner peripheral surface of the outer ring and the outer peripheral surface of the retainer is widened, and the stability during rotation of the bearing can be increased.

An inner peripheral surface of the retainer may be provided with an inclined portion that is inclined radially outward as it extends axially outward. In this case, the lubricant easily flows from the outside of the angular contact ball bearing into the bearing space along the inclined portion, thereby improving lubricity.

The retainer may have a ball retaining projection protruding toward the inner side of the pocket on an inner diameter side edge of the retainer in each pocket. When the ball holding projections of the retainer are shaped to hold the balls in this manner, the strength of the retainer in the circumferential direction can be ensured, and the strength of the retainer can be further improved.

The inner peripheral surface of the retainer has protruding portions that protrude radially inward. , the relationship d1<Hd2<d2 may be satisfied. With the above relationship, the strength of the cage pocket can be maximized while leaving a necessary margin for incorporating the cage.

An angular contact ball bearing mounted on an electric vertical take-off and landing aircraft that is equipped with a plurality of drive units having rotor blades and a motor that rotates the rotor blades, and that flies by rotating the rotor blades,
In the case of the angular contact ball bearing having any one of the configurations described above for rotatably supporting the rotating shaft of the driving portion, the angular contact ball bearing of the present invention has the effects described above.

According to the angular contact ball bearing of the present invention, HD-P. C. D. >P. C. D. -Hd, the inner diameter Hd of the outer ring guide retainer is changed to the pitch diameter of the balls P. C. D. 0.25 to 0.35 times the diameter Da of the balls, and the thickness T in the radial direction of the retainer is 0.40 to 0.45 times the diameter Da of the balls. In an angular contact ball bearing to which a guide cage is applied, the strength of the cage can be improved while maintaining the dimensions and basic performance of the bearing.

1 is a longitudinal sectional view of an angular contact ball bearing according to a first embodiment of the invention; FIG. It is an enlarged vertical cross-sectional view of the same angular contact ball bearing. FIG. 3 is a partially enlarged view of a main portion of the retainer as seen from the axial direction; It is a figure for comparing the cage with the conventional cage. FIG. 5 is a longitudinal sectional view of an angular contact ball bearing according to another embodiment of the invention; It is a longitudinal cross-sectional view of a bearing device provided with the same angular contact ball bearing and a lubricating mechanism. FIG. 6 is a vertical cross-sectional view of an angular contact ball bearing according to still another embodiment of the present invention; FIG. 6 is a vertical cross-sectional view of an angular contact ball bearing according to still another embodiment of the present invention; 1 is a perspective view of an electric vertical take-off and landing aircraft equipped with an angular contact ball bearing of the present invention; FIG. It is a longitudinal cross-sectional view of the same angular contact ball bearing, a motor, and the like. FIG. 10 is a longitudinal sectional view of an angular contact ball bearing provided with a conventional retainer;

[First Embodiment]
An angular contact ball bearing according to an embodiment of the present invention will be described with reference to FIGS. 1 to 4. FIG.
As shown in FIG. 1 , this angular contact ball bearing 11 includes inner and outer rings 12 and 13 , a plurality of balls 14 and a retainer 15 . A plurality of balls 14 are interposed between the raceway surfaces 12 a and 13 a of the inner and outer rings 12 and 13 . The balls 14 are made of steel balls, ceramics, or the like. The retainer 15 retains a plurality of balls 14 in pockets Pt provided at a plurality of locations in a cylindrical shape in the circumferential direction. The angular ball bearing 11 has a general ball diameter and number of balls corresponding to the main dimensions (inner diameter, outer diameter and width).

A raceway surface 13a is connected to a front end surface 13c of the outer ring 13 via a front inner peripheral surface 13b. The front-side inner peripheral surface 13b is a tapered surface that slopes radially inward from the front-side end surface 13c toward the raceway surface 13a, and is a counterbore. A rear-side inner peripheral surface 13 e guided by the retainer 15 is formed between the raceway surface 13 a and the rear-side end surface 13 d of the outer ring 13 . The back-side inner peripheral surface 13e is located radially inward of the front-side inner peripheral surface 13b. A raceway surface 12a is connected to a front end surface 12c of the inner ring 12 via a front outer peripheral surface 12b. A rear outer peripheral surface 12e is formed between the raceway surface 12a and the rear end surface 12d of the inner ring 12 . The back-side outer peripheral surface 12e is located radially outside the front-side outer peripheral surface 12b. The front end faces 12c and 13c of the inner and outer rings 12 and 13 represent the side faces that do not support the axial load, and the back end faces 12d and 13d of the inner and outer rings 12 and 13 represent the side faces that support the axial load. represent the sides.
The outer peripheral surface 12e on the back side of the inner ring 12, that is, the peripheral surface radially opposed to the inner peripheral surface 13b on the front side, is formed radially outwardly of the outer peripheral surface 12b on the front side of the inner ring 12 to have a predetermined dimension and a larger diameter. It is In the present embodiment, the front inner peripheral surface 13b of the outer ring 13 is tapered, but the front outer peripheral surface 12b of the inner ring 12 may be tapered, or both may be tapered. good too.

<About retainer 15>
The retainer 15 is of an outer ring-guided retainer guide type that is guided to the rear inner peripheral surface 13e of the outer ring 13, and the outer peripheral surface of the retainer 15 is formed in a cylindrical shape. At least, the outer peripheral surface of the retainer 15 at the position that serves as the outer ring guide surface of the retainer should be formed in an axially cylindrical shape. By forming the outer peripheral surface of the retainer 15 in the axially cylindrical shape at the position that serves as the outer ring guide surface of the retainer, the stability during rotation of the bearing can be improved. The retainer 15 is made of resin and has a cylindrical shape. Each pocket Pt of the retainer 15 is formed in the shape of a circular hole along the radial direction. As the resin, nylon reinforced with glass fiber, carbon fiber, or the like, polyamide resin with a high melting point, polyetheretherketone resin (abbreviation: PEEK material), phenol resin, or the like is applied.

This retainer 15 has configurations 1, 2, 3 and 4 below.

<Configuration 1: (HD-P.C.D.)>(P.C.D.-Hd)>
As shown in FIG. 1, the pitch diameter P.D. C. D. is the pitch circle diameter P. C. D. is larger than the value obtained by subtracting the inner diameter Hd of the retainer 15 from

<Structure 2: HD=D1-Sr and P.S. C. D. -0.35 Da≤Hd≤P. C. D. -0.25 Da>
The outer diameter HD of the retainer 15 is the diameter dimension of the cylindrical outer peripheral surface, and is a value obtained by subtracting the retainer radial clearance Sr from the outer ring inner diameter D1. The outer ring inner diameter D1 is the inner diameter dimension of the back side inner peripheral surface 13 e of the outer ring 13 . The cage radial clearance Sr is appropriately determined in consideration of, for example, the dimensional tolerance and radial clearance of each bearing component.

The inner diameter Hd of the cage 15 is the diameter dimension of the cylindrical inner peripheral surface, and the pitch diameter P.D. C. D. 0.25 to 0.35 times the diameter Da of the ball 14.
Therefore, the contact ellipse Ce (FIG. 3) generated by whirling of the cage 15 and contact between the balls 14 and the cage 15 does not contact the inner diameter side edge portion 15a of the pocket Pt of the cage 15 .
Table 1 shows an example of an angular contact ball bearing with bearing number 7014 (inner diameter 70 mm x outer diameter 110 mm, width 20 mm) with 13/32 inch (10.31875 mm) balls and changes in cage inner diameter and cage wall thickness. indicates

In Table 1, cages with sufficient cage strength and load-bearing performance due to the ring compression load, etc. described later, and which can be used as outer ring guide cages are marked with "O", and other cages are marked with "X".
For example, if the inner diameter Hd of the retainer is P.M. C. D. At −Da×0.20 or less, the contact ellipse Ce comes into contact with the inner diameter side edge portion 15a of the pocket Pt of the retainer 15, as shown in FIG. The inner diameter Hd of the retainer is P.M. C. D. If -Da×0.40 or more, the inner ring guides the inner ring in contact with the inner ring due to the cage wall thickness, and the outer ring guide may not be established. If the clearance is relatively narrow, the outer ring guide may be eliminated or close to it, considering the wear of the outer diameter portion of the retainer during use of the bearing.

<Configuration 3: 0.40 Da ≤ T ≤ 0.45 Da>
As shown in FIG. 2, the radial thickness (plate thickness) T of the retainer 15 is 0.40 to 0.45 times the diameter Da of the balls 14 . For example, if the thickness T of the cage is Da×0.35 or less, the cage strength or load bearing performance may be insufficient. If the thickness T of the retainer is Da×0.50 or more, it is impossible due to the structure of the retainer. This is because the radial area of the retainer is restricted to the extent that the shoulders of the inner ring and the shoulders of the outer ring require desired dimensions. Therefore, in Table 1, the case where the thickness T of the retainer is Da×0.35 and the case where the cage thickness is Da×0.5 are marked with “×”.

<Configuration 4: 1.6 Da ≤ HB ≤ 2.0 Da>
The axial width HB of the retainer 15 is set to 1.6 to 2.0 times the diameter Da of the balls 14 within a range not protruding from both ends of the angular contact ball bearing 11 in the axial direction. There is a limit to enlarging the cage on the inner diameter side in order to improve the cage strength and load bearing performance in the outer ring guide cage. For this reason, the retainer 15 is enlarged by maximally utilizing the axial region within a range that does not protrude from both ends of the inner ring 12 and the outer ring 13 in the axial direction. Further, by extending the retainer 15 in the axial direction, the sliding contact portion between the inner peripheral surface 13e on the back side of the outer ring 13 and the outer peripheral surface of the retainer is widened, and the stability during rotation of the bearing can be increased.

The retainer 15 of the angular contact ball bearing 11 of the present embodiment shown in FIG. 4 and the retainer 51 (FIG. 11) of the conventional angular contact ball bearing 50 were compared with the same bearing size. The ball diameter and the number of balls applied to the angular contact ball bearings 11 and 50 of FIGS. 4 and 11 are the same, and are determined according to the main dimensions. The conventional angular contact ball bearing 50 shown in FIG. 11 is an outer ring guide retainer, and the radial thickness of the retainer is less than 0.40 times the diameter Da of the balls 52 . Further, the axial width HBa of the conventional retainer 51 is set to be less than 1.6 times the diameter Da of the balls 52, although it does not protrude from both ends of the angular contact ball bearing 50 in the axial direction.

In this case, under the same load conditions, in the conventional cage 50 (FIG. 11), the contact ellipses of the balls 52 and the cage 51 come into contact with the inner diameter side edge portion of the pocket Pt, whereas the cage 15 in FIG. Then, the contact ellipse does not contact the inner diameter side edge portion 15a of the pocket Pt. In addition, compared to the conventional cage 51 (FIG. 11), the cage 15 of FIG. It was confirmed that the value obtained by dividing the force of the balls 14 pushing the retainer 15 against the load increased by that amount. Therefore, it was confirmed that the retainer 15 of FIG. 4 has sufficient strength as compared with the conventional retainer 51 (FIG. 11). The ring compressive rigidity is the axial compressive stress of the cylinder (cylinder crushing strength).

<Effect>
According to the angular contact ball bearing 11 described above, in the outer ring guide retainer in which the outer diameter HD of the retainer 15 is the difference between the outer ring inner diameter D1 and the retainer radial direction clearance Sr, the inner diameter Hd of the retainer 15 is set to the pitch circle of the balls 14. diameter p.m. C. D. by subtracting 0.25 to 0.35 times the diameter Da of the ball 14 from the P.D. C. D. , to the inner diameter side portion of the pocket Pt of the retainer 15 for the radial dimension. Therefore, the whirling of the cage 15 and the contact ellipse generated by the contact between the balls 14 and the cage 15 do not contact the inner diameter side edge portion 15 a of the pocket of the cage 15 . In addition, the radial thickness T of the cage 15 is 0.40 to 0.45 times the diameter Da of the balls 14, and the axial width HB of the cage 15 is 1.6 to 1.6 times the diameter Da of the balls 14. 2.0 times.

As a result, the retainer has sufficient strength against the centrifugal force generated under high-speed operation and high-load conditions or the load generated as the balls 14 lead and lag. Therefore, in the angular contact ball bearing 11 to which the outer ring guide retainer is applied, the strength of the retainer 15 can be improved while maintaining the dimensions and basic performance of the bearing.

<About other embodiments>
In the following description, the same reference numerals are given to the parts corresponding to the items previously described in each embodiment, and redundant description is omitted. When only a portion of the configuration is described, the other portions of the configuration are the same as those previously described unless otherwise specified. The same configuration has the same effect. It is possible not only to combine the parts specifically described in each embodiment, but also to partially combine the embodiments if there is no problem with the combination.

[Second Embodiment: FIGS. 5 and 6]
As shown in FIG. 5, inclined portions 16 may be provided on both sides of the pocket Pt on the inner peripheral surface of the retainer 15A in the axial direction so as to extend radially outward toward the axially outer side. . Each inclined portion 16 extends linearly in the longitudinal section of FIG. 5 from the axially intermediate portion of the inner peripheral surface of the retainer 15A to the radially outwardly inclined portion to the end surface of the retainer.

In the longitudinal section shown in FIG. 6, the inclination angle α with respect to the axial direction of the inclined portion 16 and the radial position P1 of the retainer end face at the inclined portion 16 allow air-oil to smoothly flow into the bearing space from the lubrication mechanism 17 for air-oil lubrication. , it is determined according to the radial position of the nozzle 18 of the lubricating mechanism 17, the inclination angle β of the nozzle 18 with respect to the axial direction, and the like. By setting the inclination angles α and β to satisfy the relationship of (α−5°)<β<(α+5°), the inclined portion 16 does not interfere with the flow of the air-oil into the bearing space, and the air-oil flows smoothly. It can flow into the bearing space. Other configurations 1, 2, 3 and 4 are the same as in the first embodiment.

With this configuration, air oil can easily flow from the outside of the angular ball bearing 11 into the bearing space along the inclined portion 16 from the nozzle 18 of the lubricating mechanism 17, thereby improving the lubricating property. Since the inclined portion 16 has a simple shape with a predetermined inclination angle α, it can be easily molded using a mold. In addition, the molded product after mold molding can be easily removed from the mold. The inclined portion 16 is not limited to the linear shape, and may have a curved shape or a shape in which a straight line and a curved line are smoothly connected.

[Third Embodiment: FIG. 7]
As shown in FIG. 7, the retainer 15B may have a ball holding protrusion 19 protruding toward the inside of the pocket on the inner diameter side edge of the retainer in each pocket Pt. The ball holding projections 19 have a pitch circle diameter P.1 of the cage 15B. C. D. An inclined surface 19a having an inclination angle that greatly inclines toward the inside of the pocket as it goes radially inward from the vicinity is formed. Other configurations 1, 2, 3 and 4 are the same as in the first embodiment.
When the ball holding projections 19 of the retainer 15B are shaped to hold the balls 14, the strength of the retainer 15B in the circumferential direction can be ensured, and the strength of the entire retainer can be further improved. Become. The ball holding projection 19 can also be easily molded by a mold, like the inclined portion 16 (FIG. 5). In addition, the molded product after mold molding can be easily removed from the mold.

[Fourth Embodiment: FIG. 8]
As shown in FIG. 8, the retainer 15C may be thick only at the axial rolling elements. Specifically, the inner peripheral surface of the retainer 15C is composed of projecting portions 20 where the axial rolling elements protrude radially inward, inclined portions 21 on both sides in the axial direction connected to the projecting portions 20, and each inclined portion. 21 and extending to both ends in the axial direction. The inner diameter Hd1 of the cylindrical portion 22 is determined by the pitch diameter of the balls 14 P.D. C. A value obtained by subtracting 0.25 to 0.35 times the ball diameter Da from D.

The inner diameter Hd2 of the protruding portion 20 is the sum of the outer diameter d1 on the smaller diameter side of the inner ring 12 and the required assembly margin γ. The required assembling margin γ is a requisite allowance for assembling the retainer 15C and the balls 14 into the bearing space between the inner and outer rings 12,13. The inclined portions 21 , 21 on both sides in the axial direction are inclined radially outward from both axial side edges of the projecting portion 20 toward the outside in the axial direction. Cylindrical portions 22, 22 extend axially outward from the axially outer edges of the inclined portions 21, 21, respectively. When the outer diameter of the inner ring 12 on the large diameter side is d2, the relationship between the inner diameter Hd2 of the projecting portion 20 and the outer diameter d1 of the inner ring 12 on the small diameter side may be d1<Hd2<d2. By establishing the above relationship, it is possible to maximize the strength of the cage pocket while leaving a necessary margin for incorporating the cage 15C. Other configurations 1, 2, 3 and 4 are the same as in the first embodiment. If only the axial rolling elements of the retainer 15C are thickened, the strength of the retainer 15C in the circumferential direction can be ensured, and the strength of the entire retainer can be further improved.

<Examples of application to electric vertical take-off and landing aircraft: Figures 9 and 10>
You may apply an angular contact ball bearing to an electric vertical take-off and landing aircraft.
In recent years, so-called flying cars, which are capable of flying, have attracted attention as means of transportation in place of automobiles. Flying cars are expected to be used in various situations such as transportation within and between regions, tourism and leisure, emergency medical care, and disaster relief.

As a flying car, a vertical take-off and landing aircraft (VTOL) attracts attention. Vertical take-off and landing aircraft can ascend and descend vertically between the sky and the takeoff and landing site, so they do not require a runway and are highly convenient. In recent years, in particular, electric vertical take-off and landing aircraft (eVTOL), which fly with batteries and motors, have become the mainstream of development due to social demands for reducing _CO2 emissions.

As shown in FIG. 9, the electric vertical take-off and landing aircraft 1 is a multicopter having a main body 2 positioned at the center of the aircraft body and four drive units 3 arranged on the front, rear, left and right sides. The drive unit 3 is a device that generates lift and propulsion of the electric vertical take-off and landing aircraft 1 , and the electric vertical take-off and landing aircraft 1 flies by driving the drive unit 3 . The electric vertical take-off and landing aircraft 1 may have a plurality of driving units 3, and the number is not limited to four.

The body part 2 has a living space in which passengers (for example, about one or two people) can board. This living space is equipped with an operating system for determining the direction of travel and altitude, as well as instruments for indicating altitude, speed, flight position, and the like. Four arms 2a extend radially from the body portion 2, and a driving portion 3 is provided at the tip of each arm 2a. In FIG. 9, the arm 2a is integrally provided with an annular portion that covers the rotating circumference of the rotor blade 4 in order to protect the rotor blade 4. As shown in FIG. A skid 2b is provided at the bottom of the main body 2 to support the aircraft during landing.

The drive unit 3 has a rotor blade 4 and a motor 5 that rotates the rotor blade 4 . In the drive unit 3, a pair of rotor blades 4 are provided on both sides of the motor 5 in the axial direction. Each rotor blade 4 has two blades extending radially outward.

FIG. 10 shows a partial cross-sectional view of the motor 5 in the drive section. The rotating blade 4 (FIG. 9) is attached to one end side (the upper side in FIG. 10) of the rotating shaft 7 of the motor 5, and the rotor 5a of the motor 5 is attached to the other end side (the lower side in FIG. 10). The motor 5 is of the inner rotor type, in which the rotor 5a is arranged opposite to the stator 5b fixed to the housing 6, and the rotor 5a is rotatable with respect to the stator 5b, and is of the direct drive type. It should be noted that the motor 5 can employ a configuration of an outer rotor type brushless motor or an inner rotor type brushless motor.

In FIG. 10, the motor 5 includes a housing 6, a rotor 5a, a stator 5b, and two angular ball bearings 11, 11 according to any of the embodiments described above. The housing 6 has an outer cylinder 6a and an inner cylinder 6b, and a passage 6c for flowing a cooling medium is provided between the outer cylinder 6a and the inner cylinder 6b. Excessive temperature rise of the motor 5 can be prevented by flowing the cooling medium through the flow path 6c.

The angular ball bearing 11 rotatably supports the rotating shaft 7 within the housing 6 . The outer ring 13 of the angular ball bearing 11 has the same outer diameter shape as the fitting portion on the inner periphery of the housing, and is directly fitted to the housing 6 without a bearing housing or the like. In this example, the two angular ball bearings 11, 11 are arranged back-to-back via inner and outer ring spacers 8, 9, and are preloaded.

<Regarding the control system>
The body portion 2 is provided with a control device 31 that controls the plurality of motors 5 and the like, and a battery 32 that supplies power to each motor 5 and the control device 31 . The control device 31 has an inverter that converts the DC power of the battery 32 into an AC voltage, and a control unit that controls the output of the inverter by PWM control or the like according to a torque command generated according to the operation system.
The controller changes the rotation speed of the motor 5 and the rotor blade 4 (FIG. 9) by outputting a command to change the rotation speed to the motor 5 whose lift is to be adjusted based on the difference between the current attitude and the target attitude. The adjustment of the number of rotations of the motors 5 is performed simultaneously for a plurality of motors 5, thereby determining the attitude of the airframe.

In FIG. 10, the rotating shaft of the motor 5 and the rotating shaft of the rotor blade 4 (FIG. 9) are the same rotating shaft, but the rotating shaft of the motor and the rotating shaft of the rotor blade are connected via a transmission mechanism. It may be a configuration. In this case, the angular ball bearing that supports the rotating shaft of the drive unit may be an angular ball bearing that supports the rotating shaft of the motor, or an angular ball bearing that supports the rotating shaft of the rotor.

It is also possible to use angular ball bearings in a face-to-face combination.
It is also possible to apply angular contact ball bearings to applications other than electric vertical take-off and landing aircraft.
The retainer of the angular contact ball bearing may be manufactured not only by molding with a mold, but also by machining or by a 3D printer, for example.

As mentioned above, although the form for implementing this invention was demonstrated based on embodiment, embodiment disclosed this time is an illustration and is not restrictive at all points. The scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include all modifications within the meaning and range of equivalents of the scope of the claims.

DESCRIPTION OF SYMBOLS 1... Electric vertical take-off and landing aircraft, 3... Drive part, 4... Rotor blade, 5... Motor, 7... Rotating shaft, 11... Angular contact ball bearing, 12... Inner ring, 13... Outer ring, 14... Ball, 15, 15A, 15B, 15C... Cage, 16... Inclined portion, 19... Ball holding protrusion, 20... Protruding part, Pt... Pocket

Claims (6)

An inner ring, an outer ring, a plurality of balls interposed between the inner ring and the outer ring, and a retainer for holding the balls in pockets provided at a plurality of locations in the circumferential direction, the retainer being an outer ring-guided retainer. An angular contact ball bearing of a guide type in which an outer peripheral surface of the retainer at a position serving as an outer ring guide surface of the retainer is formed in an axially cylindrical shape,
Let HD be the outside diameter of the cage, Hd be the inside diameter of the cage, and P.D. be the pitch circle diameter of the balls. C. D. When HD-P. C. D. >P. C. D. - satisfies the relationship of Hd,
The inner diameter Hd of the cage is defined by the pitch diameter P.D. of the balls. C. D. A value obtained by subtracting 0.25 to 0.35 times the diameter Da of the ball from
An angular contact ball bearing in which the radial thickness T of the retainer is 0.40 to 0.45 times the diameter Da of the ball. 2. The angular contact ball bearing according to claim 1, wherein the axial width HB of the retainer is 1.6 times the diameter Da of the balls within a range not protruding from both axial ends of the inner ring and the outer ring of the angular contact ball bearing. Angular contact ball bearings with a factor of ~2.0. 3. The angular contact ball bearing according to claim 1, wherein the inner peripheral surface of the retainer is provided with an inclined portion inclined radially outward toward the axially outward side. . 4. The angular contact ball bearing according to any one of claims 1 to 3, wherein said retainer has ball retaining projections protruding inwardly of said pocket on inner diameter side edges of said retainer in each pocket. 5. The angular contact ball bearing according to claim 4, wherein the inner peripheral surface of the retainer has a protruding portion that protrudes radially inward. An angular contact ball bearing that satisfies the relationship d1<Hd2<d2, where d2 is the inner diameter of the projecting portion and Hd2 is the inner diameter of the projecting portion. An angular contact ball bearing mounted on an electric vertical take-off and landing aircraft that is equipped with a plurality of drive units having rotor blades and a motor that rotates the rotor blades, and that flies by rotating the rotor blades,
6. The angular contact ball bearing according to any one of claims 1 to 5, wherein the rotary shaft in the driving portion is rotatably supported.

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