KR20240004650A - Angular ball bearings - Google Patents

Abstract

The angular ball bearing 11 of the present invention includes an inner ring 12, an outer ring 13, a plurality of balls 14 interposed between the inner ring 12 and the outer ring 13, and a cylindrical ball 14. It is provided with retainers 15 that hold it in pockets Pt provided at a plurality of locations in the circumferential direction. The retainer 15 is a retainer guide type of the outer ring guide. The inner diameter (Hd) of the retainer 15 was determined by subtracting 0.25 to 0.35 times the diameter (Da) of the balls 14 from the pitch circle diameter (P.C.D.) of the balls 14. The thickness (T) of the retainer (15) was set to 0.40 to 0.45 times the diameter (Da) of the balls (14).

Description

Angular ball bearings

[Related applications]

This application claims priority of Japanese Patent Application 2021-075067, dated April 27, 2021, and is hereby incorporated by reference in its entirety.

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

Angular ball bearings are widely used in bearings that support rotating bodies for high-speed operation, including the main axis of machine tools. As a retainer for this angular ball bearing, an outer ring guide retainer or a rolling element guide retainer is often used. As the retainer, a lightweight resin retainer is often used in order to reduce the influence of centrifugal force. These retainers are made of resin materials such as aliphatic polyamide resin (nylon) reinforced with glass fiber, carbon fiber, etc., aromatic polyamide resin, polyether ether ketone resin (abbreviated name: PEEK material), and phenolic resin, and are made of cylindrical shape. It is formed (for example, patent documents 1 to 3).

In order to realize high efficiency and space saving of machine tools, it is necessary to improve the high-speed rotation and load-bearing performance of the angular ball bearings that support the main axis of the machine tool. When the bearing rotates at high speed or under high load conditions, the retainer needs to have sufficient strength because an excessive load is applied from the balls due to centrifugal force and delay in the movement of the balls.

Japanese Patent Publication No. 2011-117542 Japanese Patent Publication No. 2014-95469 Japanese Patent Publication No. 2016-145644

The basic performance of angular ball bearings depends on the ball diameter and number of balls, but when the balls are made larger or the number of balls is increased, the space available to construct the retainer becomes smaller, so it is important for the retainer to have sufficient strength. There is a possibility that you will be in trouble.

In order for the retainer to have sufficient strength, it is necessary to increase the thickness of the retainer (thickness in the diametric direction), the axial width, and the spacing between pockets. However, since the basic performance of a bearing generally depends on the ball diameter and the number of balls, a retainer shape that improves the retainer strength while securing the basic performance of the bearing in a limited space within the bearing is proposed.

The purpose of the present invention is to provide an angular ball bearing with an outer ring guide retainer that can improve the strength of the retainer while maintaining the dimensions and basic performance of the bearing.

The angular ball bearing of the present invention has an inner ring, an outer ring, a plurality of balls interposed between the inner ring and the outer ring, and a cylindrical retainer that holds the balls in pockets provided at a plurality of locations in the circumferential direction, the retainer comprising: As an angular ball bearing, which is a retainer guide type of outer ring guide,

When the outer diameter of the retainer is HD, the inner diameter of the retainer is Hd, and the pitch circle diameter of the ball is P.C.D., the relationship HD-P.C.D.>P.C.D.-Hd is satisfied,

The inner diameter Hd of the retainer is set to a value obtained by subtracting 0.25 to 0.35 times the diameter Da of the ball from the pitch circle diameter P.C.D. of the ball,

The thickness T of the retainer was set to 0.40 to 0.45 times the diameter Da of the balls.

According to this configuration, the inner diameter Hd of the outer ring guide retainer is set to a value obtained by subtracting 0.25 to 0.35 times the diameter Da of the ball from the pitch circle diameter P.C.D. of the ball, so that the radial dimension from P.C.D. to the inner diameter side of the pocket of the retainer is Sufficient distance can be secured. Accordingly, the contact ellipse generated around the vibration of the retainer and the contact between the ball and the retainer does not contact the inner diameter side edge portion of the pocket of the retainer. For example, when the inner diameter Hd of the retainer is P.C.D.-Da x 0.20 or less, the contact ellipse contacts the edge portion on the inner diameter side of the pocket. When the inner diameter Hd of the cage is P.C.D.-Da If the gap between the inner diameter side and the outer diameter side of the inner ring becomes relatively narrow, considering the wear of the outer diameter portion of the retainer when using the bearing, there is a possibility that the outer ring may not be guided, or may be close to it.

Furthermore, the thickness T of the retainer was set to 0.40 to 0.45 times the diameter Da of the balls. As a result, the retainer can have sufficient strength against the centrifugal force that occurs under high-speed operation and high load conditions or the load that occurs due to the delay in ball progression. For example, if the thickness T of the cage is Da x 0.35 or less, the cage strength or load-bearing performance may become insufficient. If the thickness T of the cage is Da×0.50 or more, it becomes impossible to construct the cage. This is because the radial area of the retainer is regulated to the extent that desired dimensions are required for the shoulder portion of the inner ring and the shoulder portion of the outer ring.

Therefore, in an angular ball bearing using an outer ring guide retainer, 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 ball bearing. In the outer ring guide retainer, there is a limit to enlarging the retainer on the inner diameter side in order to improve the retainer strength and load-bearing performance. Accordingly, the retainer is enlarged by utilizing the axial area as much as possible within the range that does not protrude from both axial ends of the inner and outer rings. Additionally, by extending the retainer in the axial direction, the slide contact area between the inner peripheral surface of the outer ring and the outer peripheral surface of the retainer is expanded, and stability during bearing rotation can be increased.

On the inner peripheral surface of the retainer, an inclined portion may be provided that slopes toward the axial outer side and reaches the radial outer side. In this case, the lubricant can easily flow into the bearing space from the outside of the angular ball bearing along the inclined portion, thereby improving lubricity.

The retainer may have a ball retaining protrusion protruding inside the pocket on an inner diameter side edge of the retainer in each pocket. In this way, when the ball retaining protrusion of the retainer is shaped to hold the ball, the strength of the retainer in the circumferential direction can be secured, making it possible to further improve the strength of the retainer.

When the retainer has a protruding portion that protrudes radially inward, the outer diameter of the small diameter side of the inner ring is d1, the outer diameter of the large diameter side is d2, and the inner diameter of the protruding portion is Hd2. , d <Hd2<d2 may be satisfied. By maintaining the above relationship, the strength of the retainer pocket can be maximized while leaving the necessary margin (necessary gap) for assembling the retainer.

An angular ball bearing equipped with a plurality of driving parts having rotary blades and motors for rotating the rotary blades, and mounted on an electric vertical takeoff and landing aircraft that flies by rotation of the rotary blades, comprising:

In the case of the angular ball bearing of any of the above configurations of the present invention that rotatably supports the rotating shaft of the drive unit, each effect described above with respect to the angular ball bearing of the present invention is obtained.

Any combination of at least two configurations disclosed in the claims and/or specification and/or drawings is encompassed by the present invention. In particular, any combination of two or more of each claim in the claims is included in the present invention.

The present invention may be more clearly understood from the following description of embodiments with reference to the accompanying drawings. However, the embodiments and drawings are for simple illustration and description and should not be used to define the scope of the present invention. The scope of the present invention is defined by the appended claims. In the accompanying drawings, the same part numbers in multiple drawings indicate the same part.
1 is a longitudinal cross-sectional view of an angular ball bearing according to a first embodiment of the present invention.
Figure 2 is an enlarged longitudinal cross-sectional view of the same angular ball bearing.
Figure 3 is a partial enlarged view of the main portion of the retainer of the angular ball bearing viewed from the axial direction.
Figure 4 is a diagram for comparing the same retainer with a conventional retainer.
Figure 5 is a longitudinal cross-sectional view of an angular ball bearing according to a second embodiment of the present invention.
Figure 6 is a longitudinal cross-sectional view of a bearing device including an angular ball bearing and a lubrication mechanism.
Figure 7 is a longitudinal cross-sectional view of an angular ball bearing according to a third embodiment of the present invention.
Figure 8 is a longitudinal cross-sectional view of an angular ball bearing according to a fourth embodiment of the present invention.
Figure 9 is a perspective view of an electric vertical takeoff and landing aircraft equipped with an angular ball bearing of the present invention.
Figure 10 is a longitudinal cross-sectional view of a motor including an angular ball bearing.
Figure 11 is a longitudinal cross-sectional view of an angular ball bearing with a conventional retainer.

[First Embodiment]

An angular ball bearing according to the first embodiment of the present invention will be described with FIGS. 1 to 4.

As shown in FIG. 1, this angular ball bearing 11 includes an inner ring 12, an outer ring 13, a plurality of balls 14, and a retainer 15. The plurality of balls 14 are interposed between the raceway surfaces 12a and 13a of the inner ring 12 and the outer ring 13. The ball 14 is made of a steel ball or ceramics. The retainer 15 has a cylindrical shape and holds a plurality of balls 14 in pockets Pt provided at a plurality of locations in the circumferential direction. For this angular ball bearing (11), typical ball diameters and numbers of balls are applied according to the main dimensions (inner diameter, outer diameter and width).

In the cross section 13c on the front side of the outer ring 13, the raceway surface 13a continues through the inner peripheral surface 13b on the front side. The front inner peripheral surface 13b is a tapered surface that slopes radially inward from the front end surface 13c toward the raceway surface 13a, and is a counterbore. Between the raceway surface 13a and the end surface 13d on the back side of the outer ring 13, a back inner peripheral surface 13e for guiding the retainer 15 is formed. The back side inner peripheral surface 13e is located radially inside the front side inner peripheral surface 13b. In the cross section 12c on the front side of the inner ring 12, the raceway surface 12a continues through the front outer peripheral surface 12b. A back-side outer peripheral surface 12e is formed between the raceway surface 12a and the back-side end surface 12d of the inner ring 12. The rear outer peripheral surface 12e is located radially outer than the front side outer peripheral surface 12b. The cross sections 12c and 13c on the front side of the inner ring 12 and the outer ring 13 represent the cross section on the side that does not support the axial load, and the cross sections 12d on the back side of the inner ring 12 and the outer ring 13. 13d) shows the cross section on the side that supports the axial load.

The rear outer peripheral surface 12e of the inner ring 12, that is, the main surface radially opposite to the front inner peripheral surface 13b of the outer ring 13, is the front outer peripheral surface 12b of the inner ring 12. It is formed to have a larger diameter by a predetermined size on the outer side in the radial direction. In addition, in this embodiment, the front side inner peripheral surface 13b of the outer ring 13 is a tapered surface, but the front side outer peripheral surface 12b of the inner ring 12 may be configured with a tapered surface, and both sides are tapered surfaces. It can be configured by .

{About Maintenance (15)}

The retainer 15 is a retainer guide type of the outer ring guide guided by the inner peripheral surface 13e on the rear side of the outer ring 13, and is formed in a cylindrical shape. Since the outer peripheral surface of the cylindrical retainer 15 serves as the outer ring guide surface, stability during bearing rotation can be improved. Each pocket Pt of the retainer 15 is formed in a circular hole shape along the circumferential direction. This retainer 15 is made of a resin material such as aliphatic polyamide resin (nylon) reinforced with glass fiber, carbon fiber, etc., aromatic polyamide resin, polyether ether ketone resin (abbreviated name: PEEK material), and phenol resin. It consists of

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

{Configuration 1: (HD-P.C.D.)>(P.C.D.-Hd)}

As shown in FIG. 1, the value obtained by subtracting the pitch circular diameter P.C.D. of the balls 14 from the outer diameter HD of the retainer 15 is greater than the value obtained by subtracting the inner diameter Hd of the retainer 15 from the pitch circular diameter P.C.D. satisfies.

{Configuration 2: HD=D1-Sr and P.C.D.-0.35Da≤Hd≤P.C.D.-0.25Da}

The outer diameter HD of the cage 15 is the diameter of the cylindrical outer peripheral surface, and is a value obtained by subtracting the cage radial clearance Sr from the outer ring inner diameter D1. The outer ring inner diameter D1 is the inner diameter of the inner peripheral surface 13e on the back side of the outer ring 13. The cage radial clearance Sr is appropriately determined, for example, taking into account the dimensional tolerance and radial clearance of each bearing component.

The inner diameter Hd of the retainer 15 is the diameter of the cylindrical inner peripheral surface, and is a value obtained by subtracting 0.25 to 0.35 times the diameter Da of the balls 14 from the pitch circle diameter P.C.D. of the balls 14.

Accordingly, the contact ellipse Ce (FIG. 3) generated around the vibration of the retainer 15 and the contact between the ball 14 and the retainer 15 is located at the inner diameter side edge portion (FIG. 3) of the pocket Pt of the retainer 15. Do not touch 15a).

In Table 1, an example of applying 13/32 inch (10.31875 mm) balls to an angular ball bearing with the number 7014 (inner diameter 70 mm x outer diameter 110 mm, width 20 mm) and changing the inner diameter Hd of the retainer and the thickness T of the retainer. represents.

[Table 1]

In Table 1, those that have sufficient retainer strength and load-bearing performance due to the ring compression load, etc., which will be described later, and that can be established as an outer ring guide retainer are indicated with "○", and others are indicated with "×".

For example, when the inner diameter Hd of the retainer is P.C.D.-Da x 0.20 or less, as shown in FIG. 3, the contact ellipse Ce contacts the inner diameter side edge portion 15a of the pocket Pt of the retainer 15. When the inner diameter Hd of the cage is P.C.D.-Da If the gap between the inner diameter side and the outer diameter side of the inner ring is relatively narrow, considering wear of the outer diameter portion of the retainer when using the bearing, there is a possibility that the outer ring may not be guided, or may be close to it.

{Configuration 3: 0.40Da≤T≤0.45Da}

As shown in FIG. 2, the 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 x 0.35 or less, the cage strength or load-bearing performance may become insufficient. If the thickness T of the cage is Da×0.50 or more, it becomes impossible to construct the cage. This is because the radial area of the retainer is regulated to the extent that desired dimensions are required for the shoulder portion of the inner ring and the shoulder portion of the outer ring. Accordingly, in Table 1, “×” is indicated for the case where the thickness T of the retainer is Da x 0.35 and for the case where Da x 0.5.

{Composition 4: 1.6Da≤HB≤2.0Da}

The axial width HB of the retainer 15 (the axial direction is common to the angular ball bearing 11, the inner ring 12, the outer ring 13, and the retainer 15) is that of the angular ball bearing 11. It is set to be 1.6 to 2.0 times the diameter Da of the ball 14 in the range where it does not protrude from both ends in the axial direction. In the outer ring guide retainer, there is a limit to enlarging the retainer on the inner diameter side in order to improve the retainer strength and load-bearing performance. Accordingly, the retainer 15 is enlarged by utilizing the axial area as much as possible within the range that does not protrude from both axial ends of the inner ring 12 and the outer ring 13. Additionally, by extending the retainer 15 in the axial direction, the slide contact portion between the rear inner peripheral surface 13e of the outer ring 13 and the outer peripheral surface of the retainer becomes wider, and stability during bearing rotation can be increased.

The retainer 15 of the angular ball bearing 11 of this embodiment shown in FIG. 4 and the retainer 51 of the conventional angular ball bearing 50 (FIG. 11) were compared with the same bearing size. The ball diameter and number of balls applied to the angular ball bearings 11 and 50 of FIGS. 4 and 11 are determined according to the main dimensions of the bearings 11 and 50, and are the same for the dual bearings 11 and 50. Additionally, the conventional angular ball bearing 50 shown in FIG. 11 has an outer ring guide retainer, but the thickness of the retainer is less than 0.40 times the diameter Da of the balls 52. Furthermore, the axial width HBa of the conventional retainer 51 is within a range that does not protrude from both axial ends of the angular ball bearing 50, but is less than 1.6 times the diameter Da of the balls 52.

In this case, under the same load conditions, in the conventional retainer 50 (FIG. 11), the contact ellipse of the ball 52 and the retainer 51 contacts the inner diameter side edge portion of the pocket Pt, as shown in FIG. 4. In the retainer 15, the contact ellipse does not contact the inner diameter side edge portion 15a of the pocket Pt. In addition, compared to the conventional retainer 51 (FIG. 11), the retainer 15 in FIG. 4 has an increased ring compression rigidity by increasing the cross-sectional area of the thinnest part of the retainer 15. ), and the value obtained by dividing the force with which the ball 14 presses the retainer 15 with respect to the fatigue limit load of the retainer 15 increased accordingly. Accordingly, it was confirmed that the retainer 15 in FIG. 4 has sufficient strength compared to the conventional retainer 51 ( FIG. 11 ). The ring compressive rigidity is the axial compressive stress of the cylinder (crushing strength of the cylinder).

{action effect}

According to the angular ball bearing 11 described above, in the outer ring guide retainer where the outer diameter HD of the retainer 15 is the difference between the outer ring inner diameter D1 and the retainer radial clearance Sr, the inner diameter Hd of the retainer 15 is set to the ball (14). ) by subtracting 0.25 to 0.35 times the diameter Da of the ball 14 from the pitch circular diameter P.C.D., ensuring a sufficient distance in the radial direction from the P.C.D. to the inner diameter portion of the pocket Pt of the retainer 15. can do. Accordingly, the contact ellipse generated around the vibration of the retainer 15 and the contact between the ball 14 and the retainer 15 does not contact the edge portion 15a on the inner diameter side of the pocket of the retainer 15. .

Additionally, the thickness T of the retainer 15 is set to 0.40 to 0.45 times the diameter Da of the balls 14. As a result, the retainer can have sufficient strength against the centrifugal force that occurs under high-speed operation and high load conditions or the load that occurs due to the delay in the movement of the balls 14. Therefore, in the angular 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.

{Regarding other embodiments}

In the following description, the same reference numerals are assigned to parts corresponding to matters previously described in each embodiment, and overlapping descriptions are omitted. When only part of the structure is explained, other parts of the structure are assumed to be the same as those previously explained unless otherwise specified. The same effect can be obtained from the same composition. In addition to the combination of the parts specifically explained in each embodiment, it is also possible to partially combine the embodiments with each other, especially if there is no problem with the combination.

[Second Embodiment: Figures 5 to 6]

As shown in FIG. 5, inclined portions 16 may be provided on both axial portions of the pocket Pt on the inner peripheral surface of the retainer 15A, respectively, slanting toward the axial outer side so as to reach the radial outer side. . Each inclined portion 16 extends linearly in the longitudinal cross section of Fig. 5 from a portion near the axial direction of one axial portion on the inner peripheral surface of the retainer 15A to the end face of the retainer inclined radially outward.

In the vertical 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 cross section of the retainer in the inclined portion 16 are the lubrication mechanism for air oil lubrication ( So that air oil flows smoothly into the bearing space from 17), it is determined according to the radial position of the nozzle 18 of the lubrication mechanism 17 and the inclination angle β of the nozzle 18 with respect to the axial direction. By setting the inclination angles α and β to the relationship of (α-5°)<β<(α+5°), the inclination portion 16 does not interfere with air oil flowing into the bearing space, thereby preventing the air from flowing into the bearing space. Oil can flow smoothly into the bearing space. Other configurations 1, 2, 3, and 4 are the same as those in the first embodiment.

According to this configuration, air oil from the nozzle 18 of the lubrication mechanism 17 can easily flow into the bearing space along the inclined portion 16 from the outside of the angular ball bearing 11, thereby improving lubricity. . Since the inclined portion 16 is formed at a predetermined inclined angle α and has an uncomplicated shape, it becomes possible to easily perform molding using a mold. Additionally, the molded product after molding can be easily taken out from the mold. Incidentally, the inclined portion 16 is not limited to the above-mentioned straight shape, but may also have a curved shape or a shape in which a straight line and a curved line are smoothly connected.

[Third Embodiment: Figure 7]

As shown in Fig. 7, the retainer 15B may have a ball retaining protrusion 19 protruding inside the pocket at the inner diameter side edge of the retainer within each pocket Pt. The ball retaining protrusion 19 has a pitch circular diameter P.C.D. of the retainer 15B. It has an inclined surface 19a that slopes greatly toward the inside of the pocket as it goes radially inward in the vicinity. Other configurations 1, 2, 3, and 4 are the same as those in the first embodiment. When the ball retaining protrusion 19 of the retainer 15B is shaped to hold the ball 14, the strength of the retainer 15B in the circumferential direction can be secured, and the strength of the entire retainer can be further improved. It becomes possible. The ball retaining protrusion 19 can also be easily molded using a mold, similar to the above-described inclined portion 16 (FIG. 5). Additionally, the molded product after molding can be taken out of the mold more easily.

[Fourth Embodiment: Figure 8]

As shown in FIG. 8, the retainer 15C may be thick only at the axial rolling element portion, which is the portion that holds the rolling element in the axial direction. Specifically, the retainer 15C includes a protruding portion 20 whose axial rolling element portion protrudes radially inward, inclined portions 21 on both sides of the axial direction connected to the protruding portion 20, and each It has two cylindrical parts 22 connected by an inclined part 21 and extending to both ends in the axial direction. The inner diameter Hd1 of the cylindrical portion 22 is set to a value obtained by subtracting 0.25 to 0.35 times the diameter Da of the ball from the pitch circular diameter P.C.D of the ball 14.

The inner diameter Hd2 of the protruding portion 20 is the outer diameter d1 on the small diameter side of the inner ring 12 plus the required assembly allowance γ. The assembly required margin γ is the margin (necessary gap) required to assemble the retainer 15C and the balls 14 into the bearing space between the inner ring 12 and the outer ring 13. The inclined portions 21, 21 on both axial sides are inclined radially outward as they go outward in the axial direction from the edge portions on both axial sides of the protruding portion 20, respectively. From the axially outer edge portions of these inclined portions 21 and 21, cylindrical portions 22 and 22 extend axially outward, respectively. Additionally, when the outer diameter on the large diameter side of the inner ring 12 is d2, the relationship between the inner diameter Hd2 of the protruding portion 20 and the outer diameter d1 on the small diameter side of the inner ring 12 may be d1 < Hd2 < d2. By maintaining the above relationship, the strength of the retainer pocket can be maximized while leaving the necessary margin for assembling the retainer 15C. Other configurations 1, 2, 3, and 4 are the same as those in the first embodiment. By thickening only the axial rolling element portion of the cage 15C, the strength in the circumferential direction of the cage 15C can be secured, and the strength of the entire cage can be further improved.

{Application examples for electric vertical takeoff and landing aircraft: Figures 9 and 10}

Angular ball bearings can be applied to electric vertical takeoff and landing aircraft.

Recently, flying cars, so-called flying cars, have been attracting attention as a means of transportation replacing cars. Flying cars are expected to be used in a variety of situations, including intra-regional travel, inter-regional travel, tourism and leisure, emergency medical services, and disaster relief.

As a flying car, the Vertical Take-Off and Landing aircraft (VTOL) is attracting attention. Since vertical takeoff and landing aircraft can ascend and descend vertically, they do not require a runway and are highly convenient. In particular, in recent years, electric vertical takeoff and landing (eVTOL), a type of vehicle that flies with batteries and motors, has become the mainstream of development due to social demands for reduction of CO ₂ emissions.

As shown in FIG. 9, the electric vertical takeoff and landing aircraft 1 is a multicopter having a main body 2 located in the center of the fuselage and four drive units 3 arranged left, right, front and rear. The driving unit 3 is a device that generates lift and thrust of the electric vertical takeoff and landing aircraft 1, and the electric vertical takeoff and landing aircraft 1 flies by driving the driving unit 3. In the electric vertical takeoff and landing aircraft (1), there may be a plurality of driving units (3), but it is not limited to four.

The main body 2 has a living space where passengers (for example, about 1 to 2 people) can ride. In this living space, a control system for determining the direction of travel, altitude, etc., and meters indicating altitude, speed, flight position, etc. are installed. Four arms 2a extend radially from the main body 2, and a drive unit 3 is installed at the tip of each arm 2a. In Fig. 9, in order to protect the rotary blade 4, the arm 2a is integrally provided with an annular portion that covers the rotation periphery of the rotary blade 4. Additionally, a skid 2b is installed at the lower part of the main body 2 to maintain the aircraft during landing.

The drive unit 3 has a rotary blade 4 and a motor 5 that rotates the rotary blade 4. In the drive unit 3, a pair of rotary blades 4 are installed in the axial direction with the motor 5 interposed therebetween. Each rotary blade 4 has two blades extending outward in the radial direction.

Fig. 10 is a vertical cross-sectional view of the motor 5 in the drive unit. The rotary blade 4 (FIG. 9) is mounted on the upper side of the rotation shaft 7 of the motor 5 in FIG. 10, and the rotor 5a of the motor 5 is mounted on the lower side in FIG. 10. The motor 5 is a direct drive type in which a rotor 5a is disposed opposite to a stator 5b fixed to the housing 6, and the rotor 5a is rotatable with respect to the stator 5b. It is a form. As the motor 5, an outer rotor type brushless motor or an inner rotor type brushless motor can be adopted.

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

The angular ball bearing 11 rotatably supports the rotating shaft 7 within the housing 6. The outer circumferential shape of the outer ring 13 of the angular ball bearing 11 is the same as the fitting portion on the inner periphery of the housing, and is directly fitted into the housing 6 without intervening the bearing housing or the like. In this example, the two angular ball bearings 11, 11 are arranged back to back through the inner ring spacer 8 and the outer ring spacer 9, and a preload is applied.

{About control system}

The main body 2 is provided with a control device 31 that controls a 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 direct current power of the battery 32 into alternating current power, and a control unit that controls the output of the inverter by PWM control or the like based on a torque command generated according to the operating system.

The control unit changes the rotation speed of the motor 5 and the rotary blade 4 (FIG. 9) by outputting a command to change the rotation speed to the motor 5 to adjust the lift based on the difference between the current posture and the target posture. The rotation speed of the motor 5 is adjusted simultaneously for a plurality of motors 5, and the attitude of the aircraft is determined accordingly.

In Fig. 10, the rotation axis of the motor 5 and the rotation axis of the rotary blade 4 (Fig. 9) are the same rotation axis, but the rotation axis of the motor and the rotation axis of the rotary blade may be connected through a transmission mechanism. In this case, the angular ball bearing supporting the rotating shaft of the drive unit may be an angular ball bearing supporting the rotating shaft of the motor or may be an angular ball bearing supporting the rotating shaft of the rotating blade.

It is also possible to use angular ball bearings in a face-to-face combination.

It is also possible to apply angular ball bearings to applications other than electric vertical takeoff and landing aircraft.

The retainer of an angular ball bearing may be manufactured not only by molding using a mold, but also by, for example, mechanical processing or a 3D printer.

As described above, the preferred embodiments have been described with reference to the drawings, but those skilled in the art will be able to easily imagine various changes and modifications within the scope of the obvious by looking at the specification. Accordingly, such changes and modifications are construed as being within the scope of the present invention as defined by the appended claims.

1: Electric vertical takeoff and landing aircraft
3: Drive part
4: rotary blade
5: motor
7: Rotation axis
11: Angular ball bearing
12: Inner ring
13: paddle
14: ball
15, 15A, 15B, 15C: retainer
16: inclined portion
19: Ball holding protrusion
20: protruding part
PT: Pocket

Claims (6)

It is provided with an inner ring, an outer ring, a plurality of balls interposed between the inner ring and the outer ring, and a cylindrical retainer that holds the balls in pockets provided at a plurality of locations in the circumferential direction, and the retainer is an angular type of retainer guide of the outer ring guide. As a ball bearing,
When the outer diameter of the retainer is HD, the inner diameter of the retainer is Hd, and the pitch circle diameter of the ball is PCD, the relationship HD-PCD>PCD-Hd is satisfied,
The inner diameter Hd of the retainer is set as a value obtained by subtracting 0.25 to 0.35 times the diameter Da of the ball from the pitch circle diameter PCD of the ball,
An angular ball bearing in which the thickness T of the retainer is 0.40 to 0.45 times the diameter Da of the balls. According to paragraph 1,
An angular ball bearing in which the axial width HB of the retainer is 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 ball bearing. According to claim 1 or 2,
An angular ball bearing in which an inclined portion is provided on the inner circumferential surface of the retainer that slopes toward the axial outer side to reach the radial outer side. According to any one of claims 1 to 3,
The retainer is an angular ball bearing having a ball retaining protrusion protruding inside the pocket on an inner diameter side edge of the retainer in each pocket. According to clause 4,
The retainer has a protruding portion that protrudes radially inward, and when the outer diameter of the small diameter side of the inner ring is d1, the outer diameter of the large diameter side is d2, and the inner diameter of the protruding portion is Hd2, d1 < Hd2 < Angular ball bearing that satisfies the d2 relationship. According to any one of claims 1 to 5,
An angular ball bearing mounted on an electric vertical takeoff and landing aircraft comprising a plurality of rotary blades and a driving unit having a motor for rotating the rotary blades, and flying by rotation of the rotary blades, comprising:
An angular ball bearing that rotatably supports the rotation axis of the drive unit.