bearing

Abstract

The ball bearing (5) is a bearing that supports a shaft member (7) having turbine blades (8) that receive compressed air from an air supply port (9). The ball bearing (5) has an inner ring (10), an outer ring (20), a plurality of rolling elements (30), and a cage (31). In addition, the ball bearing (5) has a sealing member (40) that is annular around an axis (x) and is configured to close the space between the inner ring (10) and the outer ring (20). The sealing member (40) has a support ring (42) for supporting the sealing member (40) on the outer peripheral side. A sealing groove (11) having a sealing contact surface (13), a recess (14), and a protrusion (12) is formed on the outer peripheral surface (10b) of the inner ring (10). The sealing contact surface (13) allows the inner peripheral end (41a) of the sealing member (40) to contact from the outside in the axial direction (x). The recess (14) extends radially at least in the region opposite the support ring (42) along the axis (x).

Description

Technical Field

[0001] This invention relates to a bearing, and more particularly to a bearing for a dental handpiece driven by an air turbine. Background Technology

[0002] Traditionally, dental handpieces have been used in dental treatments. A dental handpiece has a head with a rotating mechanism and a tool that can be detachably attached to the head. In the rotating mechanism, a shaft member is supported at both ends by bearings, and turbine blades are mounted on the shaft member. The bearings are ball bearings with an inner ring, an outer ring, and a cage that holds multiple rolling elements (balls) between the inner and outer rings. Compressed air can be supplied to the turbine blades through a supply path. The compressed air is blown onto the turbine blades of the rotating mechanism, causing the turbine blades to rotate, the shaft member to rotate, and the tool to rotate.

[0003] Among the conventional bearings used in dental handpieces, there is one type that has a braking function, such as the one disclosed in Patent Document 1. Specifically, an annular sealing ring is fixed to the outer ring of the bearing, and the end of the inner circumferential side of the sealing ring can contact the inner ring of the bearing. When the supply of compressed air stops, the end of the inner circumferential side of the sealing ring contacts the inner ring of the bearing, applying a braking force to the inner ring and preventing the inner ring from rotating.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: German Patent Application Publication No. 102012000757 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] For the bearing with braking function used in dental handpieces as described above, a structure that can achieve higher rotation speeds is required.

[0009] The present invention was made in view of the above-mentioned problems, and its object is to provide a bearing that can achieve higher rotation speeds.

[0010] Solution for solving the problem

[0011] To achieve the above objectives, the bearing of the present invention supports a shaft member having turbine blades that rotate under compressed air. The bearing comprises: an inner ring; an outer ring disposed on the outer periphery of the inner ring; a plurality of rolling elements between the inner and outer rings; a cage holding the rolling elements at circumferential intervals; and a sealing member disposed between the inner and outer rings to close the space between them. The sealing member is annular about an axis x and has a support ring for supporting the sealing member on its outer periphery. A sealing groove with a sealing contact surface, a recess, and a protrusion is formed on the outer periphery of the inner ring. The sealing contact surface allows the inner periphery end of the sealing member to contact the outer side in the axial direction. The recess extends radially at least in the region opposite the support ring along the axial direction.

[0012] Invention Effects

[0013] The bearing according to the present invention enables higher speed rotation. Attached Figure Description

[0014] Figure 1 This is an external view of an example of a dental handpiece equipped with the bearing of the present invention.

[0015] Figure 2 It is a general representation Figure 1 A cross-sectional view of an example of the head of a dental handpiece.

[0016] Figure 3 It means used for Figure 2 The figure shown is a schematic cross-sectional view of an example of the bearing of the present invention.

[0017] Figure 4 yes Figure 3 A magnified view of a portion of the bearing shown.

[0018] Figure 5 yes Figure 3 A magnified view of a portion of the bearing shown.

[0019] Figure 6 It means used for Figure 2 The image shows a partially enlarged cross-sectional view of the schematic structure of another example of the bearing of the present invention, with the head shown. Detailed Implementation

[0020] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that, in the drawings, for multiple component elements, sometimes not all of them are labeled, but only a portion of the labels of the multiple component elements are omitted.

[0021] One embodiment of the bearing of the present invention is a high-speed rotating ball bearing for dental handpieces. Figure 1 This is an external view of a dental handpiece 1, which is an example of a dental handpiece equipped with the bearing of the present invention. Figure 2 This is a simplified cross-sectional view of the head 2, which is an example of the head of a dental handpiece 1. Figure 3 This is a cross-sectional view showing a schematic structure of a ball bearing 5, which is an example of the bearing used in the head 2 according to the present invention. Furthermore, Figure 4 , Figure 5 yes Figure 3 The image shows a partially enlarged view of the ball bearing 5. It should be noted that... Figure 4 This refers to the ball bearing 5 in the dental handpiece 1 when it is in a stopped state. Figure 5 This indicates the ball bearing 4 in the dental handpiece 1 in the driving state. It should be noted that, as described later, the stopped state is the state where compressed air does not act on the sealing member, and the sealing member does not deform due to the action of compressed air. Furthermore, the driving state is the state where compressed air acts on the sealing member, causing the sealing member to deform.

[0022] like Figure 1 , Figure 2 As shown, the dental handpiece 1 has: a head 2 with a rotating mechanism 4; and a tool 3 that is detachably attached to the head 2. When using the dental handpiece 1, the tool 3 is rotated at a high speed (e.g., more than 400,000 revolutions per minute) to perform tooth cutting, etc.

[0023] like Figure 2 As shown, the head 2 of the dental handpiece 1, in addition to having a rotating mechanism 4, also has a housing 6 that accommodates the rotating mechanism 4. Figure 2 As shown, the rotating mechanism 4 includes a shaft member 7, a pair of ball bearings 5, a turbine blade 8, and an air supply port 9. The tool 3 is detachably mounted to the shaft member 7. The shaft member 7 is located along the x-axis and is rotatably supported at both ends by the pair of ball bearings 5. It should be noted that the x-axis is the axis of the ball bearings 5. Furthermore, the turbine blade 8 is mounted between the pair of ball bearings 5 ​​in the shaft member 7. By supplying compressed air to the turbine blade 8 from the air supply port 9, the turbine blade 7 can be rotated at high speed. Thus, the shaft member 7 and the tool 3 rotate at high speed. It should be noted that the shaft member 7 rotates about the x-axis as its central axis or approximately the central axis.

[0024] As described above, the ball bearing 5 is a bearing that supports a shaft member 7 equipped with turbine blades 8, which rotate under the influence of compressed air supplied from the air supply port 9. The ball bearing 5 includes an inner ring 10, an outer ring 20 disposed on the outer periphery of the inner ring 10, a plurality of rolling elements 30 between the inner ring 10 and the outer ring 20, and a cage 31 that holds the rolling elements 30 at circumferential intervals. Furthermore, the ball bearing 5 includes a sealing member 40, which is annular around the axis x and disposed between the inner ring 10 and the outer ring 20 to close the space between them. The sealing member 40 has a support ring 42, which is an annular member for supporting the sealing member 40 on the outer periphery. A sealing groove 11 with a sealing contact surface 13, a recess 14, and a protrusion 12 is formed on the outer peripheral surface 10b of the inner ring 10 facing the outer periphery. The sealing contact surface 13 allows the inner circumferential end 41a of the sealing member 40, which is the inner circumferential side, to contact from the outside in the axial x direction. The recess 14 extends radially, at least in the region opposite the support ring 42, along the axial x direction. The structure of the ball bearing 5 will be described in detail below.

[0025] It should be noted that the outer side is one side along the x-axis, and the inner side is the other side along the x-axis. In the head 2 of the dental handpiece 1, the inner side of the ball bearing 5 is the side closer to the turbine blade 8 along the x-axis, and the outer side of the ball bearing 5 is the side farther from the turbine blade 8 along the x-axis. Furthermore, radial direction is orthogonal to the x-axis. Additionally, the inner circumferential side is the radially inner side, the radially closer to the x-axis, and the outer circumferential side is the opposite end of the inner circumferential side, the radially outer side, the radially farther from the x-axis.

[0026] like Figures 2-4 As shown, the ball bearing 5 includes: an inner ring 10 with a raceway groove 10c forming an inner ring raceway on its outer circumferential surface 10b; an outer ring 20 with a raceway groove 20c forming an outer ring raceway on its inner circumferential surface 20a; a plurality of rolling elements (balls) 30 between the inner ring raceway and the outer ring raceway; and an annular cage 31 that holds the rolling elements 30 at circumferential intervals so that they can rotate. Furthermore, the ball bearing 5 includes a sealing member 40. The sealing member 40 is provided to prevent lubricant from leaking from the inside of the ball bearing 5 or foreign matter from entering the inside of the ball bearing 5. In addition, the sealing member 40 is provided as a braking mechanism for the rotating mechanism 4. As described above, the sealing member 40 is provided between the inner ring 10 and the outer ring 20 in a manner that can close the space between the inner ring 10 and the outer ring 20.

[0027] like Figure 3As shown, the inner circumferential surface of the cage 31 faces the outer circumferential surface 10b of the inner ring 10, and the outer circumferential surface of the cage 31 faces the inner circumferential surface 20a of the outer ring 20. In the cage 31, a plurality of pockets (not shown) are provided at constant or substantially constant intervals in the circumferential direction to hold the rolling elements 30 in a rotatable manner. Figure 2 As shown, the outer ring 20 is fitted with the housing 6 at its outer peripheral surface 20b, and a shaft member 7 is fitted with the inner peripheral surface 10a of the inner ring 10. Specifically, in the head 2, a pair of ball bearings 5 ​​support the shaft member 7 with respect to the turbine blades 8. In the ball bearings 5, the inner ring 10 and the outer ring 20 are freely rotatable relative to each other about the axis x. That is, when the dental handpiece 1 is driven, i.e., when compressed air is supplied to the turbine blades 8, the inner ring 10 rotates at high speed relative to the outer ring 20.

[0028] like Figures 2-4 As shown, the sealing member 40 is located in the opening between the inner ring 10 and the outer ring 20 on the side where compressed air is discharged after passing through the ball bearing 5. That is, in each of the pair of ball bearings 5 ​​facing each other across the turbine blade 8, the sealing member 40 is located in the outer opening between the inner ring 10 and the outer ring 20. Figure 3 , Figure 4 As shown, the sealing member 40 includes a sealing body 41, a support ring 42, and a retaining ring 43. Furthermore, the sealing member 40 is fixed to the end 21 of the outer ring 20. The end 21 is the outermost end in the x-direction.

[0029] like Figure 4 , Figure 5 As shown, the sealing body 41 is an elastic, deformable plate-shaped member that is annular around axis x. Furthermore, the support ring 42 is, for example, a plate-shaped member with a specified rigidity that is annular around axis x. The inner diameter D2 of the support ring 42 is larger than the inner diameter D1 of the sealing body 41. Additionally, the retaining ring 43 is, for example, an elastic member that is annular or substantially annular around axis x. The retaining ring 43 is used to fix the sealing member 40 to the outer ring 20 via the support ring 42. The retaining ring 43 is, for example, a C-shaped ring. Figure 3 , Figure 4 As shown, the sealing body 41, support ring 42, and retaining ring 43 are fixed to the end 21 of the outer ring 20 by overlapping from the outside in the x-axis direction in the order of retaining ring 43, support ring 42, and sealing body 41. Specifically, the sealing body 41 and support ring 42 are sandwiched between the end 21 of the outer ring 20 and the retaining ring 43 by the retaining ring 43, and are fixed to the end 21 of the outer ring 20.

[0030] like Figure 3 , Figure 4 As shown, when the dental handpiece 1 stops, the sealing body 41 contacts the inner ring 10 at its inner circumferential end (inner circumferential end 41a). Figure 2 As shown, when compressed air is supplied to the turbine blades 8 from the air supply port 9, a portion of the discharged air flows from inside the rotating mechanism 4 through the gap between the inner ring 10 and outer ring 20 of the ball bearings 5 ​​to the seal body 41. That is, a portion of the discharged air flows from the inside to the outside through the gap between the inner ring 10 and outer ring 20 of each ball bearing 5, impacting the seal body 41 from the inside. Through the pressure of this discharged air, such as... Figure 5 As shown, the seal body 41 deforms, and the inner peripheral end 41a of the seal body 41 moves away from the inner ring 10, allowing air to be discharged to the outside of the ball bearing 5.

[0031] Even if the supply of compressed air is stopped to bring the rotating tool 3 to a halt, the turbine blades 8 and shaft assembly 7 will continue to rotate for a period of time due to inertia. During this period, the interior of the ball bearing 5 becomes a negative pressure state with a lower air pressure than the exterior. Therefore, air containing foreign matter may be drawn from the periphery of the dental handpiece 1 into the interior of the ball bearing 5 and the interior of the housing 6. This air suction into the housing 6 when the dental handpiece 1 stops is called the backflow phenomenon. The sealing member 40 is pressed against the inner ring 10 due to the airflow during the backflow phenomenon, suppressing the suction of air from the outside and preventing foreign matter from entering. Furthermore, the sealing member 40 acts as a brake for the rotating mechanism 4, applying braking force to the inner ring 10, which rotates due to inertia. Therefore, the sealing member 40 can shorten the time until the dental handpiece 1 stops.

[0032] As described above, the support ring 42 contacts the outer peripheral side of the seal body 41 around the entire circumference of the axis x. Therefore, it can prevent or suppress the seal body 41 from detaching from the outer ring 20 when subjected to pressure applied by compressed air. Furthermore, the support ring 42 strengthens the contact between the inner peripheral end 41a of the seal body 41 and the sealing contact surface 13 of the inner ring 10. Therefore, the support ring 42 enables a stronger braking force for the braking function of the seal body 41.

[0033] The inner ring 10 and outer ring 20 are made of stainless steel, for example, and the rolling element 30 is made of stainless steel or ceramic, for example.

[0034] The sealing member 40, and the structure consisting of the sealing member 40, the inner ring 10, and the outer ring 20, will be described in more detail.

[0035] like Figure 3 , Figure 4 As shown, the sealing member 40 is fixed to the sealing groove 22 of the outer ring 20. The sealing groove 22 is a groove recessed towards the outer peripheral surface 20b of the outer ring 20, extending in a ring shape around the axis x. Figure 4As shown, the sealing groove 22 includes an inclined surface 23, an annular surface 24, and a bottom surface 25. The inclined surface 23 is a cylindrical surface about the x-axis, located on the outer side of the x-axis in the sealing groove 22. The inclined surface 23 expands in diameter from the outer side to the inner side in the x-axis direction, and in cross-section, it is inclined radially outward as it moves from the outer side to the inner side in the x-axis direction. The annular surface 24 is an annular surface extending along a plane orthogonal to the x-axis, facing outward in the x-axis direction. The bottom surface 25 is an annular surface facing radially inward, extending between the inclined surface 23 and the annular surface 24.

[0036] In addition, such as Figure 4 As shown, the sealing groove 22 has a stepped cylindrical surface 26 and an annular surface 27 adjacent to the annular surface 24. The cylindrical surface 26 is a cylindrical surface extending inward along the x-axis from the inner circumferential end of the annular surface 24. The cylindrical surface 26 is, for example, a cylindrical surface. The annular surface 27 is an annular surface extending along a plane orthogonal to the x-axis, facing outward along the x-axis. The annular surface 27 extends from the inner end of the cylindrical surface 26.

[0037] like Figure 4 As shown, the outer peripheral end (outer peripheral end 41b) of the sealing body 41 is accommodated in the step formed by the cylindrical surface 26 and the annular surface 27, and is supported in contact with the cylindrical surface 26 and the annular surface 27. The retaining ring 43 contacts the inclined surface 23, and the sealing body 41 is clamped between the retaining ring 43 and the outer ring 20 through the support ring 42, thus fixing the sealing body 41 and the support ring 42 to the sealing groove 22.

[0038] The sealing body 41 is a ring-shaped sheet component. The sealing body 41 contains at least one resin selected from fluoropolymers, fluororubbers, nitrile rubber, hydrogenated nitrile rubber, acrylate rubber, and ethylene propylene rubber as the base resin. The base resin can be a resin impregnated with an elastomer within a porous (three-dimensional mesh structure, etc.) resin. Examples of fluoropolymers include polytetrafluoroethylene (PTFE) and perfluoroelastomers. The fluoropolymer can be a composite of PTFE and perfluoroelastomers to possess sliding properties and elasticity. For example, a composite formed by curing a liquid perfluoroelastomer impregnated with porous (three-dimensional mesh structure, etc.) PTFE can be used. Examples of fluororubbers include vinylidene fluoride (PVDF) based, tetrafluoroethylene-propylene based, and tetrafluoroethylene-perfluorovinyl ether based.

[0039] The hardness of the seal body 41 is, for example, Shore A60 to A90 (according to JIS K 6253:2012), and also Shore A70 to 90 (according to JIS K 6253:2012). The thickness T1 of the seal body 41 is, for example, 0.5 mm or less, and also 0.2 mm or less, and also 0.1 mm or less. The radial length W0 of the contact area between the seal body 41 and the support ring 42 is, for example, more than 1 / 2 and less than 3 / 4 of the radial width W1 of the seal body 41, and also more than 2 / 3 and less than 3 / 4. With such hardness and dimensions, the seal body 41 can easily and appropriately deform when the air turbine supplying compressed air is operating (with the compressed air passing through the inside of the ball bearing 5).

[0040] The tear strength of the seal body 41 according to JIS K 6252:2007 is not particularly limited, but is, for example, 50 N / mm or more, or 65 N / mm or more, or 80 N / mm or more. Furthermore, the tensile strength of the seal body 41 according to JIS K 6251:2010 is, for example, 30 MPa or more. By possessing such tear and tensile strengths, the durability of the seal body 41 during repeated operation and shutdown of the air turbine is further improved.

[0041] The support ring 42 is a ring-shaped component made of metal or resin. The support ring 42 has a higher hardness than the seal body 41. The retaining ring 43 is a component made of metal or resin. The retaining ring 43 has a structure that generates an applied force radially outward. By applying this force to the inclined surface 23 of the seal groove 22, the retaining ring 43 is forceped inward in the x-direction. Thus, as described above, the retaining ring 43 presses the seal body 41 and the support ring 42 against the annular surface 27 of the outer ring 20. In this example, the inner diameter D2 of the support ring 42 is larger than the inner diameter D1 of the seal body 41, and the inner diameter D3 of the retaining ring 43 is larger than the inner diameter D2 of the support ring 42.

[0042] like Figure 4 As shown, the inner ring 10 has the following on its outer peripheral side: an outer peripheral surface 10b, on which a raceway groove 10c for the rolling element 30 to roll is formed; and a sealing member opposing groove 11, which is opposed to the sealing member 40. The sealing member opposing groove 11 is a groove recessed toward the inner peripheral surface 10a of the inner ring 10 and extends in a ring shape around the axis x.

[0043] like Figure 4 As shown, the sealing groove 11 includes a sealing contact surface 13, a recess 14, and a protrusion 12. The sealing contact surface 13 is an annular surface surrounding the axis x, facing outward in the x-direction. The sealing contact surface 13 is connected to the outer peripheral surface 10b at its inner circumferential end. Figure 4As shown, when the air turbine stops (when no pressure generated by compressed air is applied), that is, when the dental handpiece 1 is in a stopped state, the inner peripheral end 41a of the sealing body 41 contacts the sealing contact surface 13. Thus, in the stopped state of the dental handpiece 1, the sealing body 41, which has not deformed due to the action of compressed air, contacts the sealing contact surface 13 of the inner ring 10 from the outside at its inner peripheral end 41a. It should be noted that, in the stopped state of the dental handpiece 1, the inner peripheral end 41a of the sealing body 41 may be subjected to force toward the sealing contact surface 13 of the inner ring 10, or it may not be subjected to force toward the sealing contact surface 13 of the inner ring 10. That is, in the stopped state of the dental handpiece 1, the sealing body 41 may deform, and the inner peripheral end 41a may be pressed against the sealing contact surface 13; alternatively, the sealing body 41 may not deform, and the inner peripheral end 41a may contact the sealing contact surface 13 without generating a reaction force.

[0044] like Figure 4 As shown, the recess 14 extends outward from the sealing contact surface 13 in the x-axis direction, forming an annular groove that is radially recessed inward between the sealing contact surface 13 and the protrusion 12. When viewed radially, the recess 14 extends in the x-axis direction at least in the region opposite the inner circumferential end (inner circumferential end 42a) of the support ring 42. The recess 14 preferably has at least a portion having a cylindrical surface 14a extending in the x-axis direction. The cylindrical surface 14a is a cylindrical surface or a substantially cylindrical surface with the x-axis as its central axis or approximately its central axis. In one embodiment of the invention, as... Figure 4 As shown, the recess 14 has a cylindrical surface 14a between the end (inner end 14b) connecting to the sealing contact surface 13 and the protrusion 12. The cylindrical surface 14a is radially opposed to the inner circumferential end 42a of the support ring 42 and the inner circumferential end (inner circumferential end 43a) of the retaining ring 43. As an example, Figure 4 As shown, the cylindrical surface 14a extends further outward than the retaining ring 43 in the x-axis direction. Thus, in the region radially opposite the sealing member 40, the recess 14 extends along the x-axis, thereby lessening obstruction of the flow of discharged compressed air. This improves the exhaust efficiency of the supplied compressed air, increases the flow rate of compressed air supplied to the turbine blades 8, and enables the ball bearing 5 to rotate at higher speeds. Therefore, the tool 3 can rotate at higher speeds.

[0045] like Figure 4 As shown, the protrusion 12 is a flange-like portion that connects to the outer end of the recess 14 in the x-direction. The protrusion 12 is located on the outer side of the retaining ring 43 in the x-direction. The outer diameter D4 of the protrusion 12 is smaller than the inner diameter D1 of the sealing body 41. A curved surface is formed on the inner edge (end edge 12a) of the protrusion 12 in the x-direction. For example, in Figure 4 In the cross-section shown, the end edge 12a of the protrusion 12 is depicted with convex curves on both the outer and inner sides. This makes the flow of discharged compressed air less obstructed. On the other hand, when backflow occurs, the airflow stagnates around the protrusion 12, and some air flows towards the seal body 41. This suppresses the inflow of air into the ball bearing 5 when backflow occurs. Therefore, backflow can be suppressed, and the amount of foreign matter entering the ball bearing 5 due to backflow can be reduced. Furthermore, the time from the cessation of compressed air supply to the contact between the seal body 41 and the seal contact surface 13 can be shortened, as can the time from the stopping of the tool 3. This improves braking performance.

[0046] Preferably, the outer end (outer end 14c) of the recess 14 in the x-direction is as follows: Figure 5 As shown, in the state where the dental handpiece 1 is driven (under compressed air pressure), it is located outside the axial x-direction of the inner peripheral end 41a of the deformed seal body 41. Furthermore, the minimum distance L1 between the deformed seal body 41 and the recess 14 or protrusion 12 is preferably greater than or equal to the thickness T1 of the seal body 41. It should be noted that... Figure 5 In the embodiment of the invention shown, the minimum distance L1 is the radial distance between the deformed sealing body 41 and the recess 14, but the minimum distance L1 is not limited to this. For example, the minimum distance L1 can also be the distance in the x-axis direction. More preferably, the minimum distance L1 is more than 1.2 times the thickness of the sealing body 41. Further preferably, the size of the gap between the deformed sealing body 41 and the sealing contact surface 13, the recess 14, and the protrusion 12 gradually increases toward the minimum distance L1. In this way, the length of the recess 14 extending in the x-axis direction is sufficiently long, and the gap between the sealing body 41 and the recess 14 or the protrusion 12 is sufficiently large, thereby making the flow of the discharged compressed air less obstructed.

[0047] Furthermore, as described above, the material of the sealing body 41 is such that it is more easily deformable. Additionally, the hardness and dimensions of the sealing body 41 are designed to further enhance its deformability. Therefore, the sealing body 41 is more easily deformable than conventional sealing bodies. Consequently, in the dental handpiece 1 in the driving state, when compressed air acts on the sealing body 41, it deforms more significantly, and the flow of compressed air discharged through the ball bearing 5 to the outside of the head 2 is less obstructed.

[0048] Thus, according to the ball bearing 5, the flow of compressed air discharged to the outside of the head 2 through the ball bearing 5 is less obstructed, and the rotation speed of the rotating mechanism 4 of the dental handpiece 1 in the driving state can be increased to a higher speed.

[0049] Furthermore, as described above, the seal body 41 is more prone to deformation than conventional seal bodies. Therefore, in the state of inertial rotation where the dental handpiece 1 stops while the turbine blades 8 and shaft member 7 continue to rotate due to inertia, when a negative pressure forms inside the ball bearing 5, this negative pressure can press the seal body 41 more forcefully against the seal contact surface 13. Therefore, even if the seal body 41 wears over time, the reduction in braking performance of the seal body 41 can be suppressed. Thus, according to the ball bearing 5, the durability of the braking mechanism can be improved, thereby extending the period for which the desired braking performance is achieved. Furthermore, the braking performance of the seal body 41 can be improved.

[0050] Furthermore, for example, by adjusting the inner diameter D2 of the support ring 42, the working area of ​​the inner peripheral end 41a of the seal body 41 when compressed air is applied can be varied. This allows adjustment of the flow rate of compressed air discharged to the outside of the head 2 via the ball bearing 5. For example, if the inner diameter D2 of the support ring 42 is increased, the inner peripheral end 41a of the seal body 41 can deform more significantly, increasing the flow rate of compressed air discharged to the outside of the head 2 via the ball bearing 5. This allows for a higher rotation speed of the rotating mechanism 4 of the dental handpiece 1 in the driving state. On the other hand, by decreasing the inner diameter D2 of the support ring 42, the rotational speed of the rotating mechanism 4 of the dental handpiece 1 can be reduced, and the braking performance of the seal body 41 can be improved.

[0051] Thus, based on the ball bearing 5, when adjusting the rotation speed and braking performance of the rotating mechanism 4 of the dental handpiece 1, it is not necessary to make changes to the internal structure of the bearing, the lubricating oil, the design of the dental handpiece, the flow rate of compressed air, and other structural changes of the dental handpiece as in the past. Only the inner diameter D2 of the support ring 42 needs to be changed, and the rotation speed and braking performance of the rotating mechanism 4 of the dental handpiece 1 can be easily adjusted.

[0052] As described above, the ball bearing 5 according to an embodiment of the present invention can achieve higher rotation speeds.

[0053] Next, the ball bearing 5A, which is another example of the bearing of the present invention, will be described. The ball bearing 5A has a sealing groove 11A that is different from the sealing groove 11 described above, compared to the ball bearing 5 described above. Hereinafter, regarding the structure of the ball bearing 5A, structures that are the same as or have the same function as the ball bearing 5 described above will be marked with the same reference numerals and their descriptions will be omitted; structures that are different from the ball bearing 5 described above will be described.

[0054] Figure 6 This is a partially enlarged cross-sectional view showing the schematic structure of a ball bearing 5A, another example of the bearing used in the head 2, which is part of the present invention. It should be noted that... Figure 6This indicates the ball bearing 5A in the dental handpiece 1 when it is in a stopped state. That is, compressed air is not acting on it. Figure 6 The sealing body 41 of the ball bearing 5A shown is not deformed. Figure 6 As shown, the inner ring 10 of the ball bearing 5A has a seal groove 11A that is different from the seal groove 11 of the ball bearing 5 described above.

[0055] like Figure 6 As shown, when compressed air is not applied to the sealing body 41, i.e., when the sealing body 41 is not deformed, the sealing contact surface 13 of the sealing groove 11A does not contact the inner peripheral end 41a of the sealing body 41. That is, as Figure 6 As shown, when compressed air is not applied to the sealing body 41, an annular gap G is formed between the inner peripheral end 41a of the sealing body 41 and the sealing contact surface 13 of the sealing groove 11A. The inner peripheral end 41a of the sealing body 41 is positioned opposite the sealing contact surface 13 of the sealing groove 11A from the outside in the x-axis direction through the gap G.

[0056] The width W of the clearance G is set as follows: when the dental handpiece 1 is stopped but the turbine blade 8 and shaft member 7 are rotating due to inertia, and the inside of the ball bearing 5 is under negative pressure, this negative pressure attracts the sealing body 41, pressing the inner circumferential end 41a of the sealing body 41 against the sealing contact surface 13. It should be noted that the width W of the clearance G is the width of the clearance G in the x-axis direction. For example, the width W of the clearance G is less than or equal to the thickness T1 of the sealing body 41.

[0057] According to ball bearing 5A, the seal body 41 contacts the seal contact surface 13 only when the dental handpiece 1 is stopped and the turbine blade 8 and shaft member 7 are rotating due to inertia, and the interior of the ball bearing 5 is under negative pressure. Therefore, the contact time between the seal body 41 and the seal contact surface 13 of the rotating inner ring 10 can be shortened, reducing wear between the seal body 41 and the seal contact surface 13. Thus, even if the inner diameter D2 of the support ring 42 is reduced to prevent deformation of the inner circumferential end 41a of the seal body 41, wear between the seal body 41 and the seal contact surface 13 can be reduced. Therefore, the braking capacity of the seal body 41 can be improved, and the durability of the seal body 41 can be increased.

[0058] Furthermore, ball bearing 5A can perform the same function as ball bearing 5 described above, and can achieve the same effect as ball bearing 5 described above.

[0059] It should be noted that, in the ball bearing 5 described above, when the dental handpiece 1 is stopped and the inner circumferential end 41a of the seal body 41 is not subjected to force toward the sealing contact surface 13 of the inner ring 10, similarly to the ball bearing 5A described above, it can reduce wear between the seal body 41 and the inner ring 10, improve the braking capacity of the seal body 41, and improve the durability of the seal body 41. This is because it can shorten the contact time between the seal body 41 and the sealing contact surface 13 when the dental handpiece 1 is driven or stopped.

[0060] The present invention has been described above through the above embodiments, but the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications or improvements can be made to the above embodiments. It is evident from the claims that forms incorporating such modifications or improvements may also be included within the technical scope of the present invention.

[0061] The embodiments described above are for the purpose of facilitating understanding of the present invention and are not intended to limit or explain the present invention. Furthermore, the above embodiments do not limit the scope of application of the present invention; the present invention can be applied to all objects. The components, their configurations, materials, conditions, shapes, and dimensions, etc., included in the above embodiments are not limited to those illustrated and can be appropriately modified. For example, the present invention includes manufacturing tolerances and other differences that may arise during implementation. Furthermore, the components shown in different embodiments can be partially substituted or combined with each other to the extent that they do not create technical contradictions. In addition, the structures can be appropriately and selectively combined to achieve at least some of the aforementioned problems and effects.

[0062] Explanation of reference numerals in the attached figures

[0063] 1: Dental handpiece; 2: Head; 3: Tool; 4: Rotating mechanism; 5, 5A: Ball bearing; 6: Housing; 7: Shaft component; 8: Turbine blade; 9: Air supply port; 10: Inner ring; 10a: Inner circumferential surface; 10b: Outer circumferential surface; 10c: Raceway groove; 11, 11A: Seal opposing groove; 12: Protrusion; 12a: End edge; 13: Seal contact surface; 14: Recess; 14a: Cylindrical surface; 14b: Inner end; 14c: Outer end; 20: Outer ring; 20a: Inner circumferential surface; 20b: Outer circumferential surface Surface; 20c: raceway groove; 21: end; 22: seal groove; 23: inclined surface; 24: annular surface; 25: bottom surface; 26: cylindrical surface; 27: annular surface; 30: rolling element; 31: cage; 40: sealing member; 41: seal body; 41a: inner circumferential end; 41b: outer circumferential end; 42: support ring; 42a: inner circumferential end; 43: retaining ring; 43a: inner circumferential end; D1, D2, D3, D4: inner diameter; G: clearance; L1: minimum distance; T1: thickness; W: width; x: axis.

Claims

1. A bearing for supporting a shaft member, said shaft member having turbine blades that are rotated by compressed air, said bearing comprising: Inner circle; The outer ring is disposed on the outer periphery of the inner ring; Multiple rolling elements are located between the inner ring and the outer ring; A cage holds the rolling elements at circumferential intervals; and A sealing member is disposed between the inner ring and the outer ring in a manner that closes the space between the inner ring and the outer ring, the sealing member being annular about axis x. The sealing member has a support ring, which is an annular component used to support the sealing member on its outer peripheral side. On the outer peripheral surface of the inner ring facing the outer peripheral side, a sealing groove is formed, which includes a sealing contact surface, a recess, and a protrusion. The sealing contact surface allows the inner circumferential end of the sealing member to contact from the outside in the axial direction. The recess extends radially along the axial direction, at least in the region opposite the support ring.

2. The bearing according to claim 1, wherein, When not subjected to the compressed air, the sealing contact surface contacts the end of the inner circumferential side of the sealing member.

3. The bearing according to claim 1, wherein, When not subjected to compressed air, the sealing contact surface does not contact the end of the inner circumferential side of the sealing member.

4. The bearing according to any one of claims 1 to 3, wherein, The bearing also includes a retaining ring, which is an annular component used to fix the sealing member to the outer ring over the support ring. The recess extends radially along the axial direction in the region opposite the retaining ring and the support ring.

5. The bearing according to claim 4, wherein, The protrusion is adjacent to the contact surface of the seal from the outside along the axial direction, separated by the recess. The protrusion is located further outward than the retaining ring in the axial direction. The outer diameter of the protrusion is smaller than the inner diameter of the sealing member.

6. The bearing according to any one of claims 1 to 5, wherein, A curved surface is formed at the inner end of the protrusion in the axial direction.

7. The bearing according to any one of claims 1 to 6, wherein, The outer end of the recess in the axial direction is located outside the inner circumferential end of the sealing member that is deformed by the compressed air in the axial direction.

8. The bearing according to any one of claims 1 to 7, The minimum distance between the end of the inner circumferential side of the sealing member, which is deformed by the compressed air, and the recess or the protrusion is greater than or equal to the thickness of the sealing member.

9. The bearing according to claim 8, wherein, The minimum distance is at least 1.2 times the thickness of the sealing member.

10. The bearing according to any one of claims 1 to 9, wherein, The sealing member includes a sealing body, which is an elastic member that is annular around the axis. The base material of the sealing element body is a resin impregnated with an elastomer in a porous resin.

11. The bearing according to claim 10, wherein, The base material of the sealing element is a composite of porous polytetrafluoroethylene and perfluoroelastomer.

12. The bearing according to any one of claims 1 to 11, wherein, The hardness of the main body of the seal, according to JIS K 6253:2012, is Shore A60 to A90.

13. The bearing according to claim 12, wherein, The hardness of the main body of the seal, according to JIS K 6253:2012, is Shore A70 to A90.

14. The bearing according to any one of claims 1 to 13, wherein, The sealing member includes a sealing body, which is an elastic member that is annular around the axis. The thickness of the main body of the seal is less than 0.5 mm.

15. The bearing according to claim 14, wherein, The thickness of the main body of the seal is less than 0.2 mm.

16. The bearing according to claim 15, wherein, The thickness of the main body of the seal is less than 0.1 mm.

17. The bearing according to any one of claims 1 to 16, wherein, The sealing member includes a sealing body, which is an elastic member that is annular around the axis. The radial length of the contact area between the sealing element body and the support ring is more than 1 / 2 and less than 3 / 4 of the radial width of the sealing element body.

18. The bearing according to claim 17, wherein, The radial length of the contact area between the sealing element body and the support ring is more than 2 / 3 and less than 3 / 4.

19. The bearing according to any one of claims 1 to 18, wherein, The sealing member includes a sealing body, which is an elastic member that is annular around the axis. The material of the main body of the seal has a tear strength of 50 N / mm or higher, according to JIS K 6252:2007.

20. The bearing according to claim 19, wherein, The material of the main body of the seal has a tear strength of 65 N / mm or higher according to JIS K 6252:2007.

21. The bearing according to claim 20, wherein, The material of the main body of the seal has a tear strength of 80 N / mm or higher according to JIS K 6252:2007.

22. The bearing according to any one of claims 1 to 21, wherein, The sealing member includes a sealing body, which is an elastic member that is annular around the axis. The material of the main body of the seal has a tensile strength of 30 MPa or higher, according to JIS K 6251:2010.

23. The bearing according to any one of claims 1 to 22, wherein, The shaft component is included in the rotating mechanism of a dental handpiece.

24. The bearing according to claim 23, wherein, The bearing is each of a pair of bearings that support the shaft member across the turbine blades. The inner side in the axial direction is the side of the turbine blade.

Images