JP2017155822A - Seal-provided bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve lower torque and higher speed of a seal-provided bearing which prevents the intrusion of foreign matters having a specified particle diameter, and has a seal lip of an axial lip.SOLUTION: A projection 154 is formed on a seal lip 151 of an axial lip. An oil passage 180 communicating between a bearing interior space 170 and the exterior and not allowing the passing of foreign matters having a specified particle diameter, is formed between a seal slide face 113 sliding in a circumferential direction with respect to the projection 154, and the seal lip 151. With the rotation of the bearing, lubrication oil in the oil passage 180 is drawn into an interspace between the seal lip 151 and the seal slide face 113, and oil film formation in the interspace is promoted.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a bearing with a seal including a rolling bearing and a seal member.

  For example, foreign substances such as gear wear powder are mixed in transmissions mounted on vehicles such as automobiles and various construction machines. For this reason, the seal member prevents foreign matter from entering the bearing internal space and prevents the rolling bearing from being damaged early.

  A general seal member has a seal lip formed of a rubber-like material or the like. A bearing sliding surface that rotates in the circumferential direction with respect to the seal member, such as a bearing ring and a slinger, is formed with a seal sliding surface that makes the seal lip slide. Since the seal lip and the seal sliding surface are in sliding contact over the entire circumference, the bearing torque increases due to the drag resistance (seal torque) of the seal lip. Moreover, the friction of the sliding contact promotes the temperature rise of the rolling bearing. As the temperature rises, an adsorption action due to a pressure difference between the bearing internal space and the outside is caused, and the friction increases.

  Conventionally, a seal member having an axial lip is used as the seal lip. An axial lip is a seal sliding surface along the radial direction or a seal sliding surface having an acute angle gradient of less than 45 ° with respect to the radial direction, and a seal lip having a sealing action. There is an axial allowance in between.

  In order to suppress the seal torque of such a seal member, by performing shot peening on the seal sliding surface, a seal sliding surface having minute irregularities with a maximum roughness Ry of 2.5 μm or less is obtained, and the lubricating oil stored in the concave portion is used. It has been proposed to promote oil film formation between the seal lip and the seal sliding surface (Patent Document 1).

JP 2007-107588 A

  However, the torque reduction by shot peening as in Patent Document 1 is brought about by reducing the sliding area between the axial lip and the seal sliding surface. Torque was limited.

  Also, in the initial stage of bearing operation, the temperature of the lubricating oil is relatively low, so the viscosity of the lubricating oil is relatively high, and it is in a lubricating condition where it is easy to form an oil film. Then, it becomes the lubrication conditions which an oil film is easy to cut | disconnect. As the bearing is operated at higher speed, the relative peripheral speed of the seal sliding surface with respect to the axial lip increases, and heat generation due to friction between the axial lip and the sealing sliding surface increases. Wear tends to progress. For this reason, there are limits to the high speed operation and allowable rotational speed of the bearing with seal due to lubrication conditions. In an electric vehicle (EV), there is a strong demand for high-speed operation of a bearing with a seal that supports a rotating part of a drive system, but the reduction in torque by shot peening cannot meet the demand.

  If a non-contact seal member is used, it is possible to eliminate the seal torque, but it becomes difficult to manage various errors that can prevent the entry of a foreign substance having a predetermined particle size with respect to the size of the gap between the seal member and the bearing component.

  In view of the above-described background, the problem to be solved by the present invention is to reduce the torque and speed of a sealed bearing having a seal member having a seal lip of an axial lip while preventing the entry of a foreign substance having a predetermined particle diameter. That is.

  In order to achieve the above object, the present invention provides a seal member that divides the bearing internal space and the outside, a seal lip provided as an axial lip on the seal member, and a circumferential slide relative to the seal lip. A seal sliding surface and a protrusion formed at least in one circumferential direction of the seal lip, and an oil passage communicating between the bearing internal space and the outside between the seal sliding surface and the seal lip; The seal lip is configured as a bearing with a seal in which the protrusion is formed in such a manner that a fluid lubrication state can be established between the seal lip and the seal sliding surface.

According to the above configuration, an oil passage is formed between the seal sliding surface and the seal lip of the axial lip, and the lubricating oil in the oil passage is dragged between the seal sliding surface and the seal lip due to the wedge effect as the bearing rotates. And promote oil film formation during this period. For this reason, since the bearing operation can be performed in a state where the seal lip and the seal sliding surface are completely separated by the oil film and are not in direct contact with each other (that is, fluid lubrication state), the seal torque is brought close to substantially zero, and the seal lip is substantially reduced. Heat generation due to sliding between the seal lip and the seal sliding surface can be suppressed. Accordingly, an allowable speed as a relative peripheral speed of the seal sliding surface with respect to the seal lip is increased, and it is possible to meet a demand for a high-speed operation of a bearing with a seal that cannot be achieved conventionally. Furthermore, the adsorption action is also prevented.
Further, the particle size of the foreign matter that can pass through the oil passage can be determined based on the protrusion height of the protrusion. Accordingly, it is possible to arbitrarily determine the particle diameter to prevent intrusion and prevent foreign matters having the predetermined particle diameter from entering from the oil passage.
As described above, the present invention can reduce the torque and increase the speed of the sealed bearing including the seal member having the seal lip of the axial lip while preventing the intrusion of the foreign substance having the predetermined particle diameter by adopting the above configuration. it can.

Sectional drawing which shows the bearing with a seal concerning the 1st example of this invention Enlarged view of the vicinity of the seal lip of the right seal member in FIG. Fig. 2 is an enlarged sectional view taken along line III-III in Fig. 2. The partial front view which shows the seal lip which concerns on 1st Example from an axial direction The figure which shows the particle size distribution and number of the foreign material contained in the lubricating oil in a transmission (AT / MT) of a vehicle Pie chart showing the ratio of particle size distribution in FIG. The figure which shows the particle size distribution and number of the foreign material contained in the lubricating oil in the transmission (CVT) of a vehicle Pie chart showing the ratio of particle size distribution in FIG. Lubrication area diagram explaining fluid lubrication mode The partial perspective view which shows the seal lip which concerns on 2nd Example of this invention (A) is a schematic diagram showing a state of vulcanization molding of the seal lip of FIG. 10, and (b) is a schematic diagram of the seal lip molded in (a). (A) is a schematic diagram showing the state of vulcanization molding of a virtual model seal lip, (b) is a schematic diagram of the seal lip molded in (a). Sectional drawing which shows an example of a transmission provided with the bearing with a seal concerning this invention

A preferred embodiment of the present invention will be described.
In the first embodiment, the protrusions are arranged at uniform intervals over the entire circumference in the circumferential direction. According to the first embodiment, oil film formation can be uniformly promoted over the entire circumference of the seal sliding surface.

  In the second embodiment, the gap between the protrusion and the seal sliding surface is formed in a wedge shape that is large on the oil passage side and small on the protrusion side. According to the second embodiment, as the bearing rotates, the lubricating oil in the oil passage is easily dragged to the protrusion side due to the wedge effect generated in the gap between the protrusion and the seal sliding surface. An oil film is easily formed between the surfaces. Further, the protrusion shape corresponding to the wedge shape can reduce the area of the sliding contact that has a great influence on the seal torque.

  In the third embodiment, the protrusion extends in a direction orthogonal to the circumferential direction, and the protrusion gradually approaches the seal sliding surface from both ends of the circumferential width toward the center of the circumferential width. It has a shape. According to the third embodiment, the protrusion extends in a direction orthogonal to the circumferential direction that is the sliding direction with the seal sliding surface, and has an R shape that reduces the area in which the protrusion can come into sliding contact. A region where the protrusion and the sliding surface of the seal are in sliding contact with each other can be linear. In addition, with such an R shape, the wedge angle of the aforementioned wedge-shaped gap gradually decreases from the wide side toward the narrow side, so that the wedge effect is effectively generated and the hydraulic pressure in the linear region is increased. Therefore, the lubrication state between the protrusion and the seal sliding surface can be easily changed to the fluid lubrication state. Further, even when the protrusion is rubbed against the seal sliding surface when the seal member is attached, there is no concern that the R-shaped protrusion will bend in the circumferential direction from the tip, and there is no fear that the sealing torque reduction performance will be impaired during attachment.

  In the fourth embodiment, the seal member has an outer lip that forms a labyrinth clearance on the outer side than the seal sliding surface. According to the fourth embodiment, the labyrinth clearance formed outside the seal sliding surface makes it difficult for foreign matter to enter the seal sliding surface to adversely affect the bearing life.

  A first embodiment according to the present invention will be described below with reference to FIGS. As shown in FIG. 1, the first embodiment includes an inner ring 110, an outer ring 120, a plurality of rolling elements 140 held by a cage 130, and a bearing inner space formed between the inner ring 110 and the outer ring 120. The bearing 100 with seal is provided with two seal members 150 and 160 that seal both ends. Hereinafter, the direction along the bearing central axis of the sealed bearing 100 is referred to as “axial direction”. The direction orthogonal to the axial direction is called “radial direction”. The circumferential direction around the bearing central axis is called “circumferential direction”.

  An annular bearing inner space 170 is formed by the inner ring 110 and the outer ring 120. The plurality of rolling elements 140 revolve while being interposed between the inner ring 110 and the outer ring 120 in the bearing inner space 170. Lubricating oil is supplied to the bearing internal space 170 by appropriate means such as grease and an oil bath.

  The inner ring 110 is attached to a rotating shaft (not shown) and rotates integrally with the rotating shaft. The rotating shaft is provided, for example, as a vehicle transmission or a differential rotating portion. The outer ring 120 is attached to a member that applies a load from the rotating shaft, such as a housing or a gear.

  This sealed bearing 100 is a ball bearing in which balls are used as the rolling elements 140. The inner ring 110 and the outer ring 120 each have a raceway groove 111, 121 that corresponds to about one third of the circumference of the rolling element 140 in a transverse cross section (corresponding to the cross section shown in the figure) and is uninterrupted over the entire circumference in the circumferential direction. .

  Seal grooves 122 and 122 for holding the seal members 150 and 160 are formed at the inner peripheral end of the outer ring 120. The seal members 150 and 160 are held in the seal grooves 122 and 122 of the outer ring 120. The seal members 150 and 160 are attached to the outer ring 120 by press-fitting their outer peripheral edges into the seal grooves 122 and 122.

  The seal members 150 and 160 separate the bearing inner space 170 from the outside, and seal both ends of the bearing inner space 170. On the outer side with the seal members 150 and 160 as a boundary, there are foreign matters according to the installation destination of the bearing 100 with seal, such as gear wear powder, clutch wear powder, and fine crushed stone. Such powdery foreign matter can reach the vicinity of the seal members 150 and 160 by the flow of lubricating oil or atmosphere. Seal members 150 and 160 prevent foreign matter from entering the bearing internal space 170 from the outside.

  The seal members 150 and 160 include seal lips 151 and 161 provided as axial lips, and outer lips 152 and 162 located on the outer side of the seal lips 151 and 161.

  Here, the axial lip is a seal lip that exhibits a sealing action with a seal sliding surface along the radial direction or a seal sliding surface with an acute angle gradient of less than 45 ° with respect to the radial direction. This means that there is an axial allowance between the moving surface.

  Seal grooves 112 and 112 are formed at the outer peripheral end of the inner ring 110 over the entire circumference. The seal sliding surfaces 113 and 114 that slide in the circumferential direction with respect to the seal lips 151 and 161 of the seal members 150 and 160 are groove side surfaces that expand from the bottom of the seal grooves 112 and 112 toward the raceway groove 111. And has an acute angle gradient α of less than 45 ° with respect to the radial direction.

  The seal grooves 112 and 112 are formed in a pair of shoulder portions 115 and 116 formed on both sides of the raceway groove 111 of the inner ring 110. Among these shoulder portions 115 and 116, the shoulder portion 115 on the load side (right side in the drawing) that receives an axial load is formed higher than the shoulder portion 116 on the opposite non-load side (left side in the drawing). The shoulder 116 on the non-load side has a shoulder height equivalent to a deep groove ball bearing. Therefore, the bearing 100 with a seal has a load capacity of an axial load superior to that of the deep groove ball bearing, while exhibiting good low torque characteristics of the deep groove ball bearing. The outer ring 120 also has a shoulder height difference between the shoulder on the load side and the shoulder on the non-load side.

  Since there is a large diameter difference between the outer diameter of the load-side shoulder 115 and the outer diameter of the non-load-side shoulder 116, the diameter of the seal sliding surface 113 formed on the load-side shoulder 115 is The diameter of the seal sliding surface 114 formed on the shoulder 116 on the non-load side is different. That is, the diameter of the seal sliding surface 113 on the right side in the drawing is larger than the diameter of the seal sliding surface 114 on the left side in the drawing. For this reason, during the bearing operation, the peripheral speed of the seal sliding surface 113 on the right side in the drawing becomes higher than that of the seal sliding surface 114 on the left side in the drawing.

  Further, during the operation of the bearing, in the bearing internal space, a pumping action for sending the lubricating oil from the left side to the right side in the figure occurs due to the above-described difference in diameter between the shoulder portions 115 and 116.

  Between the seal member 150 on the right side in the drawing and the seal member 160 on the left side in the drawing, the outer diameter difference corresponding to the diameter difference between the seal groove 122 on the right side in the drawing and the seal groove 122 on the left side in the drawing of the outer ring 120. And an inner diameter difference corresponding to the difference in diameter between the seal sliding surface 113 on the right side of the inner ring 110 and the seal sliding surface 114 on the left side of the drawing is set. Yes. Therefore, further details of the seal members 150 and 160 will be described using the seal member 150 on the right side in the figure as a representative example, and the seal member 160 is given the same reference numerals as those in FIG.

  FIG. 2 is an enlarged view of the vicinity of the seal lip 151 of the seal member 150 of FIG. 3 is a cross-sectional view taken along line III-III in FIG. This cross section is orthogonal to the seal sliding surface 113 in terms of design with respect to a gap in a direction orthogonal to the seal sliding surface 113 (including an oil passage 180 described later) between the seal lip 151 and the seal sliding surface 113. It shows the situation in the narrowest direction. Moreover, the external appearance when the seal lip 151 is viewed in the axial direction from the bearing internal space side is shown in FIG. FIG. 4 depicts the outer shape of the seal lip 151 in the natural and natural state of the seal member 150 shown in FIG. Here, the natural state means a state where no external force is applied to the seal member in a single state, that is, the state where the seal member is not deformed by the external force (hereinafter, this state is simply referred to as “natural”). Call it a state. ")

  As shown in FIGS. 2 to 4, the seal lip 151 has a protrusion 154 having a protrusion height in a direction perpendicular to the seal sliding surface 112, that is, a normal direction perpendicular to a tangent line contacting the seal sliding surface 112. Have. Since the seal sliding surface 113 is in the shape of a conical surface having a gradient α, the direction orthogonal thereto is equivalent to a direction perpendicular to the gradient α.

  A tightening margin in the axial direction and the radial direction is set between the seal lip 151 and the seal sliding surface 113. Due to this tightening allowance, the seal lip 151 pressed against the seal sliding surface 113 in the axial direction and the radial direction causes a rubber-like elastic deformation that is bent to the outside, and generates a tightening force of the seal lip 151. A mounting error, a manufacturing error, and the like of the seal member 150 are absorbed by a change in the degree of bending of the seal lip 151.

  As shown in FIG. 4, the seal lip 151 has a tip 153 that defines the inner diameter of the seal lip 151 in a natural state.

  As shown in FIGS. 2 to 4, the protrusion 154 extends in a direction orthogonal to the circumferential direction. The protrusion 154 extends to the tip 153 of the seal lip 151 and is formed over substantially the entire range having an axial interference with the seal sliding surface 113.

  The protrusions 154 are arranged at a constant interval d in the circumferential direction. Considering the appearance of the seal lip 151 viewed from the axial direction, the plurality of protrusions 154 appear in a radial pattern arranged in the circumferential direction at a constant pitch angle θ corresponding to the distance d. In addition, the radiation center is on the center axis (coincident with the bearing center axis) of the seal member 150 (not shown).

  The protrusion 154 has an R shape that gradually approaches the seal sliding surface 113 from both ends of the circumferential width w toward the center of the circumferential width. The R shape is provided over the entire length of the protrusion 154 in the radial direction. Therefore, the region where the protrusion 154 and the seal sliding surface 113 can come into sliding contact exists linearly on the virtual axial plane Pax passing through the center of the circumferential width of the protrusion 154. The center of curvature of the R shape of the protrusion 154 is on the virtual axial plane Pax.

  The distance d between the circumferentially adjacent projections 154 and the circumferential width w of the projections 154 are coupled with the fact that the radially arranged projections 154 exist near the tip 153 of the seal lip 151. The lip 151 can come into sliding contact with the seal sliding surface 113 only on each protrusion 154, and the oil passage 180 is always generated between the protrusions 154. That is, when the seal member 150 is attached, the protrusion 154 that contacts the seal sliding surface 113 is stretched against the tight force of the seal lip 151, so that the bearing inner space 170 and the outer side on both sides in the circumferential direction with the protrusion 154 as a boundary. An oil passage 180 communicating between them is formed. The lubricating oil passes from the outside through the oil passage 180 to the bearing internal space 170. Lubricating oil that has entered the bearing internal space 170 and base oil in the case where grease is sealed reach the outside through the oil passage 180 from the bearing internal space 170. In FIG. 1, the seal lip 151 corresponding to the natural state is drawn to show the tightening margin between the seal sliding surface 113 and the protrusion 154, and in FIG. 2, the oil passage 180 is generated by attaching the seal member 150. The shape of the sealed seal lip 151 is depicted.

  The particle diameter that can pass through the oil passage 180 can be determined based on the protrusion height h of the protrusion 154 in the direction orthogonal to the seal sliding surface 113. Accordingly, the first embodiment can arbitrarily determine the particle diameter to prevent intrusion and prevent foreign matters having the predetermined particle diameter from entering the bearing internal space 170 shown in FIG. 1 from the oil passage 180. is there.

  The wear powder that causes early breakage of the rolling bearing is a foreign matter having a particle diameter exceeding 50 μm. If the protrusion height h of the protrusion 154 shown in FIG. 2 is set to 0.05 mm or less, an oil passage 180 through which such wear powder cannot pass can be generated. On the other hand, in order to improve the oil permeability of the oil passage 180, the protrusion height h of the protrusion 154 is preferably set to 0.05 mm or more.

  The gap formed between the protrusion 154 and the seal sliding surface 113 is formed in a wedge shape in which the side close to the oil passage 180 in the circumferential direction is large and the side close to the protrusion 154 in the circumferential direction is small. As shown in FIG. 3, when the seal sliding surface 113 rotates in the circumferential direction with respect to the seal lip 151 as the inner ring 110 rotates (the direction of rotation is indicated by an arrow A in the figure), the oil passage. The lubricating oil in 180 (indicated by a dot pattern in the figure) is dragged between the seal sliding surface 113 and the projection 154 of the seal lip 151 as the seal sliding surface 113 rotates, and an oil film is formed between them. Promote. For this reason, the friction coefficient (μ) between the seal lip 151 and the seal sliding surface 113 is lowered, and the seal torque is reduced. Further, oil permeability between the bearing internal space 170 and the outside is improved by the oil passage 180. For this reason, the temperature rise of the bearing 100 with a seal | sticker is suppressed and by extension, the adsorption | suction effect | action of the seal lip 151 is also prevented.

  As shown in FIG. 1, the seal member 150 is formed by a metal core 156 made of a metal plate and a vulcanized rubber material 157 attached to at least an inner diameter portion of the metal core 156. The seal lip 151 and the outer lip 152 are formed of a vulcanized rubber material 157. The seal lip 151 and the outer lip 152 are branched from the waist portion that is gradually thinner in the axial direction from the portion adhering to the metal core 156 toward the seal lip 151, and each has a tongue-like shape on the inner peripheral side of the seal member 150. Sticks out. The cored bar 156 is a press-worked part formed in an annular shape over the entire circumference. The vulcanized rubber material 157 is a vulcanized rubber part. The seal member 150 is manufactured as an integral part by, for example, placing the cored bar 156 in a mold and vulcanizing and molding the vulcanized rubber material 157. The vulcanized rubber material 157 may be attached to the entire core bar 156 or may be attached only to the inner diameter portion of the core bar 156.

  The protrusions 154 are formed in a direction along the radial direction during vulcanization molding. In FIG. 1, the shape of the seal lip 151 corresponding to the natural state is drawn in order to show the tightening allowance between the seal sliding surface 113 and the protrusion 154. When the projection 154 is pressed against the seal sliding surface 113 from the axial direction, the seal lip 151 is inclined so as to substantially follow the seal sliding surface 113, and between the projection 154 and the seal sliding surface 113, as shown in FIG. Oil passage 180 and a wedge-shaped gap are generated.

  As described above, in the first embodiment, the protrusion 154 can be formed on the seal lip 151 at the time of vulcanization molding of the seal lip 151, and the seal sliding surface 113 is formed into a cylindrical surface that is easy to process, It is easy to directly form the raceway with the same cross-sectional shape over the entire circumference, such as a groove shape.

  Due to the tight force of the seal lip 151 and the oil pressure of the lubricating oil, the solid protrusion 154 is not substantially deformed (deformation that affects the lubrication performance between the protrusion 154 and the seal sliding surface 113). Yes. Therefore, the shape of the protrusion 154 during the bearing operation may be considered to be the same as the shape transferred when the seal lip 151 is vulcanized.

  The outer lip 152 forms a labyrinth clearance 190 between the outer groove wall portion of the seal groove 112. For this reason, foreign substances having a particle diameter exceeding 50 μm cannot easily enter the seal groove 112 from the outside.

  This sealed bearing 100 is assumed to be used for supporting a rotating part in a transmission of a vehicle. Oil supply to a bearing with a seal present in a transmission of a vehicle is generally performed by an appropriate method such as splashing, an oil bath, nozzle injection, or the like. Therefore, lubricating oil exists around the seal fixed to the inner ring or the outer ring of the bearing with seal. The lubricating oil to be supplied is commonly used in other lubricating parts such as gears existing in the transmission. The lubricating oil is circulated by an oil pump, and is filtered by an oil filter provided in the circulation path.

  The inventor of the present application collects the lubricating oil actually used in the market according to the mileage of the vehicle, and investigated the number of foreign matters mixed in the used lubricating oil, the particle size distribution of the foreign matters, and the foreign material. . FIG. 5 shows the number of foreign substances and the particle size distribution of the lubricating oil collected from the eight vehicles of the automatic transmission (AT) or the manual transmission (MT). The vertical axis in FIG. 5 is a logarithmic scale, the horizontal axis is the distance traveled by the vehicle, and the vertical axis is the number of foreign substances (fine particles) per 100 ml. The foreign objects to be counted were those having a particle size of 5 μm or more. Counting was performed for each particle size category. The particle size ranges from 5 μm to less than 15 μm, particle size from 15 μm to less than 25 μm, particle size from 20 μm to less than 50 μm, particle size from 50 μm to less than 100 μm, and particle size of 100 μm or more. In this measurement, a fine particle substance amount method was used with a measuring machine of model number 8000A manufactured by Hiac Royco. The particle size distribution of FIG. 5 is shown as a pie chart in FIG.

  FIG. 7 shows the number of foreign matters and the particle size distribution of the lubricating oil collected from 10 vehicles of continuously variable transmissions (CVT), as in FIG. The particle size distribution of FIG. 7 is shown as a pie chart in FIG. Vehicle manufacturers, vehicle types, and travel distances that are subject to collection vary, but as is clear from a comparison between FIGS. 5, 6, 7, and 8, AT / MT that uses a lot of gear is better than CVT There was also a tendency for both the particle size of foreign matter and the number of foreign matters to be large. Regardless of the type of transmission, the particle size distribution accounted for 99.9% or more when the particle size was 50 μm or less. The number of foreign matters having a particle size exceeding 50 μm was less than 1000 in the case of AT / MT and less than 200 in the case of CVT even when the travel distance was increased. This indicates that in recent years, the performance of the oil filter has been improved, and foreign matters in the lubricating oil have become finer (that is, foreign matters having a large particle diameter are removed by the oil filter).

  On the other hand, when the lubricating oil inside the bearing contains foreign matter, the relationship between the particle size of the foreign matter and the bearing life was investigated, and there is a tendency for the bearing life to decrease as the foreign matter with larger particle size increases. However, if there is a small amount of foreign matter with a particle size of 50 μm or more as in recent transmission environments, the life ratio of the rolling bearing (actual life even if foreign matter enters the bearing without seal) It was found that the ratio to the calculated life) shows a value (for example, about 7 to 10 times) that can be sufficiently put into practical use in an automobile transmission.

  Based on the above results, when lubricating oil filtered by an oil filter is supplied to a bearing with a seal that is used to support a rotating part of a drive system such as a transmission of a vehicle or a differential gear, a large particle size exceeding 50 μm is required. As long as the seal member prevents foreign matter from entering the inside of the bearing, it can be said that there is no problem in bearing life even if foreign matter having a particle size of 50 μm or less contained in the lubricating oil is allowed to enter the bearing. If this is allowed, fluid flow between the seal lip and the seal sliding surface should be ensured, and the lubrication between the seal lip and the seal sliding surface should be combined with the aforementioned wedge effect. It is feasible to get into the state.

  Therefore, as shown in FIGS. 2 and 3, the height h of the protrusion 154 is set to 0.05 mm. The height h of the protrusion 154 is a value at the highest position in the range in which sliding contact with the seal sliding surface 113 is possible in design. This position is also where the tightening margin set between each protrusion 154 and the seal sliding surface 113 is maximized. Since the deformation amount of the protrusion 154 during the operation of the bearing is negligible, a gap (including the oil passage 180) in the direction perpendicular to the seal sliding surface 113 between the seal lip 151 and the seal sliding surface 113 is a seal sliding. The narrowest portion in the direction orthogonal to the surface 113 has a width corresponding to the height h of the protrusion 154 and does not substantially exceed 0.05 mm. For this reason, even if a foreign matter having a particle size of more than 50 μm is included in the external lubricating oil, it is considered that the foreign matter hardly passes through the oil passage 180.

  When the seal sliding surface 113 rotates relative to the seal lip 151 in the direction indicated by the arrow A in the drawing, the lubricating oil in the oil passage 180 is dragged into the wedge-shaped gap between the protrusion 154 and the seal sliding surface 113. Is included. The wedge angle in the aforementioned wedge-shaped gap gradually decreases from the wide oil passage 180 where the drawn lubricating oil is present toward the narrow side, so that the protrusion 154 and the seal sliding surface 113 are in sliding contact with each other. The closer to the linear region to be obtained (on the virtual axial plane Pax), the stronger the wedge effect occurs. Accordingly, the oil pressure of the oil film in the linear region can be increased more effectively, the protrusion 154 can be completely separated from the seal sliding surface 113, and the oil film in the linear region can be generated thickly. It becomes easy to make the lubrication state between 154 and the seal sliding surface 113 a fluid lubrication state.

  Here, if there is an oil film that completely separates the protrusion 154 and the seal sliding surface 113, a fluid lubrication state is reached in which the seal sliding surface 113 slides against the protrusion 154 without being in direct contact. . By maintaining such an oil film between each protrusion 154 and the seal sliding surface 113, the space between the seal lip 151 and the seal sliding surface 113 can be in a fluid lubrication state.

The fluid lubrication condition, theoretically calculated, (see FIG. 9) in the lubricating area diagram in the case of a line contact which is based on the viscosity parameter _{g v} and elastic parameter _{g e} is a dimensionless number decided in Greenwood-Johnson, etc viscosity - This corresponds to a lubrication mode corresponding to one of a rigid body region (RI mode) or an isoviscous-elastic body region (EI mode, soft EHL). In addition, the plot shown in FIG. 9 illustrates the case corresponding to the RI mode or EI mode.

  In order to easily realize the fluid lubrication state, it is better to set the tightening force of the seal lip 151 based on the tightening margin between the seal lip 151 and the seal sliding surface 113 as weak as possible. For this reason, the waist | hip | lumbar part which gives the bending deformation to the exterior side among the seal lips 151 is formed as thinly as possible.

  Further, the smaller the maximum height roughness Rz is, the smaller the thickness of the oil film necessary for achieving a fluid lubrication state. For this reason, shot peening processing is not performed on the seal sliding surface 113, and the maximum height roughness Rz of the seal sliding surface 113 is set to less than 1 μm. Here, the maximum height roughness Rz refers to the maximum height roughness defined in JIS standard B0601: 2013.

  The protrusion 154 may be formed on the seal lip 151 in such a manner that the height h is set to 0.05 mm or less and the space between the seal lip 151 and the seal sliding surface 113 can be in a fluid lubrication state. The mode can be determined by the interval d between the projections 154 adjacent in the circumferential direction, the circumferential width w of the projections 154, the pitch angle θ of the projections 154 arranged at a constant interval in the circumferential direction, and the shape of the projections 154. The smaller the distance d between the protrusions 154, that is, the greater the number of protrusions 154, the more times the protrusion 154 passes per rotation when the seal sliding surface 113 rotates relative to the seal lip 151 in the circumferential direction. Since the oil film is maintained continuously over the entire circumference of the seal sliding surface 113 and the wedge effect between the protrusions 154 is easily generated without interruption, it is easy to maintain the fluid lubrication state. Become.

  In addition, a wedge effect is more likely to occur when the R dimension of the protrusion 154 (the radius of curvature of the surface 155 of the protrusion 154) is larger.

  If the oil film thickness between the protrusion 154 and the seal sliding surface 113 is too thin, the friction coefficient μ increases, and conversely, if it is too thick, there is a possibility of deteriorating the invasion effect of foreign matter. An optimum oil film thickness may be set on the assumption that the oil film thickness exceeds Rz.

  Further, the number of protrusions 154 on the right seal member 150 in FIG. 1 is different from the number of protrusions 164 on the left seal member 160 in the drawing. Further, the circumferential pitch angle of the protrusion 154 in the right seal member 150 in FIG. 1 is different from the circumferential pitch angle of the protrusion 164 in the left seal member 160 in FIG. These differences are the difference in the lubrication conditions due to the above-described difference in peripheral speed and pump action between the seal member 150 and the seal sliding surface 113 on the right side in FIG. 1 and between the seal member 160 and the seal sliding surface 114 on the left side in the drawing. Therefore, it is necessary to make the oil film formed between these left and right parts equal and to optimize the formation so that the entry of foreign matter having a particle diameter of more than 50 μm is not likely to occur due to the formation of an oil film that is too thick. It is set as a purpose.

  As described above, the sealed bearing 100 according to the first embodiment has a seal member having the seal lips 151 and 161 of the axial lip that allows foreign matters having a particle size that adversely affect the bearing life to enter the bearing internal space. The friction coefficient μ of sliding between the seal lips 151 and 161 and the seal sliding surfaces 113 and 114 is reduced to the limit by fluid lubrication while being prevented by 150 and 160, and thus the seal torque is remarkably reduced and the bearing rotational torque is reduced. Can be significantly reduced (see FIGS. 1 and 3).

  Further, the bearing 100 with a seal has a peripheral speed (for example, 30 m / s or more) of the seal sliding surface that would cause a problem of heat generation due to wear of the seal lip or sliding between the seal lip and the seal sliding surface. ), It is possible to achieve a fluid lubrication state without direct contact between the seal lips 151 and 161 of the axial lip and the seal sliding surfaces 113 and 114, so that the wear of the seal lips 151 and 161 is substantially reduced. In addition, the above-described heat generation can be suppressed. For this reason, this bearing 100 with a seal | sticker can respond to the request | requirement of the high-speed driving | operation of the bearing with a seal | sticker which was not able to be achieved conventionally.

  Further, since the protrusion 154 is formed in an R shape in the bearing 100 with a seal, even when the protrusion 154 is rubbed against the seal sliding surface 113 when the seal member 150 is attached to the outer ring 120, the protrusion 154 is formed from the tip. There is no concern of bending in the circumferential direction, and there is no risk of impairing the sealing torque reduction performance during installation. For example, when the protrusions are pointed, it is not possible to know which side of the circumferential direction the ends of the many protrusions rubbed against the seal sliding surface when the seal member is attached, and in the direction of relative rotation with the seal sliding surface. On the other hand, it is extremely difficult to attach all the protrusions so as to bend in a direction in which a proper wedge-shaped gap is formed. A wedge effect cannot be satisfactorily obtained at a protrusion bent in an inappropriate direction, and the sealing torque reduction performance is impaired.

  Furthermore, since this bearing 100 with a seal makes it difficult for foreign matter to reach the seal lips 151 and 161 due to the formation of the labyrinth clearance 190, foreign matter intrusion can be further suppressed so as not to hinder the reduction in torque. Generally, the seal lips 151 and 161 provided as axial lips have a larger axial movement amount during the operation of the bearing than the seal lips provided as radial lips, and the corresponding seal sliding surface at the time of the maximum movement. There may be a large gap between them. For this reason, providing the seal lips 151 and 161 as the axial lips is disadvantageous for foreign matter intrusion. In the bearing 100 with seal, such a disadvantage can be compensated by the sealing effect by the labyrinth clearance 190, so there is no fear that the bearing life is greatly inferior to the radial lip.

  A second embodiment will be described with reference to FIGS. In the second embodiment, only the projection shape is changed from the first embodiment. As shown in FIG. 10, the protrusion 201 according to the second embodiment has a shape that gradually decreases toward the tip 203 of the seal lip 202. FIG. 10 is an enlarged perspective view of the vicinity of the protrusion 201 of the seal lip 202 in a natural state. The R dimension of the protrusion 201 (the radius of curvature at the surface 204 of the protrusion 201) and the center of curvature are gradually reduced toward the tip 203 of the seal lip 202 in order to make the protrusion 201 gradually lower toward the tip 203 of the seal lip 202. And the center of curvature is moved to the outside.

  The height of the protrusion 201 is substantially zero on the tip 203 of the seal lip 202. For this reason, the projection 201 does not reach the tip 203 of the seal lip 202, and a flat surface 205 exists between the projection 201 and the tip 203 of the seal lip 202. That is, the tip 203 of the seal lip 202 is substantially an edge where two conical surfaces intersect, and the surface 205 is substantially a part of one of the conical surfaces.

  FIG. 11 shows a state where the seal lip 202 is vulcanized. Note that FIG. 11 is drawn schematically for easy understanding, and the shape of the seal lip 202 is also roughly shown. Vulcanization of the seal lip 202 is performed by vulcanizing and molding a rubber sheet on the core metal 206. At this time, a rubber sheet is sandwiched between the upper mold Mp1 and the lower mold Mp2, and a rubber portion such as the seal lip 202 of the seal member is molded. The vertical direction in which the upper mold Mp1 and the lower mold Mp2 are combined corresponds to the axial direction. Accordingly, the tip 153 that defines the inner diameter of the seal lip 151 in the natural state is a boundary line between the upper surface portion of the seal lip 151 in contact with the transfer surface of the upper mold Mp1 and the lower surface portion of the seal lip 151 in contact with the transfer surface of the lower mold Mp2. Therefore, it is located on the parting line Pl that is the joining portion of the upper mold Mp1 and the lower mold Mp2.

  Now, assuming a model in which a protrusion extends to the tip of the seal lip, FIG. 12 is obtained. In this virtual model, since the unevenness for forming the projection 201 ′ on the tip 203 ′ of the seal lip 202 ′ is present on the parting line Pl, a burr 207 as shown in the figure is likely to occur after vulcanization. When the burr 207 is generated, the burr 207 is separated from the seal lip 202 ′ during the operation of the bearing, which causes clogging of the oil filter and the lubricating oil circulation path.

  On the other hand, as shown in FIG. 11, when the seal lip 202 has a flat surface 205 between the protrusion 201 and the tip 203 of the seal lip 202, the unevenness for forming the protrusion 201 on the parting line Pl. No burr 207 as shown in FIG. 12 is generated. Thus, according to the second embodiment, it is possible to prevent burrs from being generated on the tip 203 of the seal lip 202 when the seal lip 202 is vulcanized.

  The second embodiment shows an example in which the protrusion 201 does not have a height on the tip 203 of the seal lip 202 and a flat surface 205 exists between the protrusion 201 and the tip 203 of the seal lip 202. However, even when the protrusion has a height on the tip of the seal lip, if the protrusion is gradually lowered toward the tip of the seal lip, the uneven shape for forming the protrusion on the parting line is gentle. Therefore, it is possible to make it difficult to generate burrs on the tip of the seal lip.

  FIG. 13 shows an example in which a bearing with a seal according to the present invention is used as a rolling bearing for supporting a rotating portion of a transmission of a vehicle. The illustrated transmission is a multi-stage transmission that changes the gear ratio stepwise, and the above-described embodiment is used as a bearing B with a seal that rotatably supports a rotating portion (for example, the input shaft S1 and the output shaft S2). Such a bearing with a seal is provided. The illustrated transmission includes an input shaft S1 to which engine rotation is input, an output shaft S2 provided in parallel with the input shaft S1, and a plurality of gear trains G1 to G4 that transmit the rotation from the input shaft S1 to the output shaft S2. Each of the gear trains G1 to G4 and a clutch (not shown) incorporated between the input shaft S1 or the output shaft S2, and the gear trains G1 to G4 used by selectively engaging the clutches. This changes the speed ratio of the rotation transmitted from the input shaft S1 to the output shaft S2. The rotation of the output shaft S2 is output to the output gear G5, and the rotation of the output gear G5 is transmitted to the differential gear or the like. The input shaft S1 and the output shaft S2 are rotatably supported by a bearing B with a seal, respectively. Further, the transmission is splashed or sprayed by splashing of the lubricant accompanying the rotation of the gear or by jetting of lubricant from a nozzle (not shown) provided inside the housing H. However, it is applied to the side surface of each bearing B with a seal.

  In each of the above-described embodiments, the protrusion has an R shape. However, the protrusion cannot be in a fluid lubrication state when the relative peripheral speed with respect to the seal sliding surface is equal to or higher than a certain value, and has a rust effect. An appropriate shape may be used so as to be obtained. For example, a chamfered shape such as an R chamfer or a C chamfer can be employed.

  Further, in each of the above-described embodiments, the example in which the protrusions are uniformly arranged in the circumferential direction has been described. However, the protrusions may be arranged unevenly or only at one place in the circumferential direction. The oil passage can be formed by the protrusion even at one place, and the effect of reducing the seal torque can be expected.

  In each of the above-described embodiments, the seal member is composed of a core metal and a vulcanized rubber material. However, the present invention can also be applied to a seal member formed of a single material. . In this case, it suffices if a required tightening allowance can be set for the seal lip. For example, a rubber material or a resin material can be used as the material of the seal member.

  In each of the above-described embodiments, the inner ring rotation and the radial bearing are exemplified. However, the present invention can be applied to the outer ring rotation and the thrust bearing.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. Accordingly, the scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

100, B Sealed bearing 110 Inner ring 112, 122 Seal groove 113, 114 Seal sliding surface 120 Outer ring 140 Rolling element 150, 160 Seal member 151, 161, 202 Seal lip 152, 162 Outer lip 153, 203 Tip 154, 164, 201 Protrusions 155, 204 Surfaces 156, 166, 206 Core bars 157, 167 Vulcanized rubber material 170 Bearing internal space 180 Oil passage 190 Labyrinth clearance S1 Input shaft (rotating part)
S2 Output shaft (rotating part)

Claims (7)

A seal member for separating the bearing internal space and the exterior;
A seal lip provided as an axial lip on the seal member;
A seal sliding surface sliding in a circumferential direction with respect to the seal lip;
An oil passage formed between at least one circumferential direction of the seal lip and communicating between the bearing internal space and the outside, and between the seal sliding surface and the seal lip.
A bearing with a seal in which the protrusion is formed on the seal lip in such a manner that a fluid lubrication state can be established between the seal lip and the seal sliding surface.   The bearing with a seal according to claim 1, wherein the protrusions are arranged at uniform intervals over the entire circumference in the circumferential direction.   The bearing with a seal according to claim 1 or 2, wherein a gap between the protrusion and the seal sliding surface is formed in a wedge shape that is large on the oil passage side and small on the protrusion side.   The protrusion extends in a direction orthogonal to the circumferential direction, and the protrusion has an R shape that gradually approaches the seal sliding surface from both ends of the circumferential width toward the center of the circumferential width. 3. A bearing with a seal according to 3.   The bearing with a seal according to any one of claims 1 to 4, wherein the seal member has an outer lip that forms a labyrinth clearance outside the seal sliding surface.   The bearing with a seal according to any one of claims 1 to 5, wherein the seal lip is formed of a vulcanized rubber material attached to at least an inner diameter portion of a cored bar.   The bearing with a seal according to any one of claims 1 to 6, which supports at least one rotating portion in a transmission and a differential of a vehicle.

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