Sealing device and bearing device equipped therewith

Abstract

The present invention provides a sealing device capable of stably electrically connecting a first member and a second member, and a bearing device equipped therewith. [Solution] A sealing device 10 for sealing an annular space S between a first member 2 and a second member 3 that rotate on an axis relative to each other, comprising a mounting portion 13 attached to the first member and a lip portion 15 extending toward the second member and elastically contacting the second member, and a conductive sealing portion 12 for electrically connecting the first member and the second member, wherein the lip portion comprises a lip tip portion 17 which is substantially circular in radial cross-sectional view and a lip base portion 16 which is provided so as to be connected to the lip tip portion and is formed such that the dimensions of the lip portion in the direction perpendicular to the extension direction and circumferential direction are smaller than those of the lip tip portion.

Description

Technical Field

[0001] The present invention relates to a sealing device and a bearing device provided with the same.

Background Art

[0002] Conventionally, in a bearing device including a first member and a second member that rotate relative to a shaft, in order to suppress the occurrence of electrical erosion when an electric current flows, the first member and the second member are configured to be electrically conductive. This is known. For example, Patent Document 1 below discloses a rolling bearing in which the bearing inner space is filled with conductive grease. Further, Patent Document 2 below discloses a conductive bearing in which a conductive ring that electrically conducts between an outer ring and an inner ring is disposed therebetween.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the rolling bearing disclosed in Patent Document 1 above, there is a concern that if the grease runs out, the electrical conductivity cannot be maintained. Further, in the conductive bearing disclosed in Patent Document 2 above, since the tip of the tapered conductive lip is configured to contact the inner ring, if there is eccentricity or the like between the outer ring and the inner ring, there is a concern that the contact of the conductive lip with the inner ring becomes unstable during rotation of the bearing.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a sealing device that can stably electrically conduct a first member and a second member, and a bearing device provided with the same.

Means for Solving the Problems

[0006] To achieve the above objective, configuration 1 of the sealing device of the present invention is a sealing device for sealing an annular space between a first member and a second member that rotate relatively on an axis, and comprises a mounting portion attached to the first member and a lip portion extending toward the second member and elastically contacting the second member, and a conductive sealing portion that electrically connects the first member and the second member, wherein the lip portion comprises a lip tip portion that is substantially circular in radial cross-sectional view and a lip base portion provided so as to be connected to the lip tip portion and formed such that the dimensions of the lip portion in the direction perpendicular to the extension direction and the circumferential direction are smaller than those of the lip tip portion.

[0007] The following description of embodiments reveals that the sealing device according to the present invention may have the following dependent configurations. <Configuration 2> In configuration 1, the sealing portion is provided to connect the mounting portion and the lip portion, and may include a sealing ring portion that covers the external space side of the core member to which the sealing portion is fixed. <Structure 3> In configuration 1 or configuration 2, the tip of the lip may have a plurality of protrusions that project from the circumferential surface and contact the second member.

[0008] To achieve the above objective, the bearing device of the present invention comprises a first member and a second member that rotate axially relative to each other, and a sealing device of configuration 1 or configuration 2 that seals the annular space between them, wherein the second member is provided with a groove for receiving the tip of the lip. Furthermore, in order to achieve the above objective, another bearing device of the present invention comprises a first member and a second member that rotate axially relative to each other, and a sealing device of configuration 3 that seals the annular space between them, wherein the second member is provided with a groove portion having an inner surface that receives the tip portion of the lip and into contact with the plurality of protrusions. Furthermore, in order to achieve the above objective, another bearing device of the present invention comprises a first member and a second member that rotate axially relative to each other, and one of the three sealing devices (configuration 1 to configuration 3) that seals the annular space between them, wherein the circumferential surface of the second member from the axial end on the external space side to the contact surface to which the lip tip elastically contacts is formed in a cylindrical shape. [Effects of the Invention]

[0009] Because the sealing device and bearing device equipped therewith of the present invention have the above-described configuration, the first member and the second member can be electrically connected stably. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic longitudinal cross-sectional view showing an example of a bearing device to which a sealing device according to one embodiment of the present invention is attached. [Figure 2] This is an enlarged view of section X in Figure 1, which is a schematic longitudinal cross-sectional view illustrating the sealing device. [Figure 3] This is a schematic longitudinal cross-sectional view illustrating a modified example of the bearing device fitted with the sealing device. [Figure 4] (a) is a schematic longitudinal cross-sectional view illustrating a modified example of the sealing device, and (b) is a schematic longitudinal cross-sectional view illustrating a bearing device equipped with the sealing device. [Modes for carrying out the invention]

[0011] Hereinafter, an example of a sealing device and a bearing device equipped therewith according to this embodiment will be described with reference to the drawings. Note that in some of the drawings, some of the detailed reference numerals used in other drawings have been omitted. Also, the seal portion shown by the dashed line in the drawings shows the shape in its natural state before elastic deformation. Figure 1 is a schematic diagram showing an example of a bearing device equipped with a sealing device, and Figure 2 is a schematic diagram showing an example of a sealing device according to this embodiment and the main parts of the bearing device.

[0012] As shown in Figures 1 and 2, the sealing device 10 seals the annular space S between the first member 2 and the second member 3, which rotate axially relative to each other. The sealing device 10 has a mounting portion 13 attached to the first member 2 and a lip portion 15 that extends toward the second member 3 and elastically contacts the second member 3. With this configuration, the mounting portion 13 attached to the first member 2 and the lip portion 15 elastically contacting the second member 3 can effectively suppress the intrusion of foreign matter such as muddy water and the leakage of fillers such as grease to the outside. The sealing device 10 includes a conductive sealing portion 12 that electrically connects the first member 2 and the second member 3. With this configuration, the first member 2 and the second member 3 can be electrically connected, and the occurrence of electrolytic corrosion when current flows can be suppressed. The lip portion 15 comprises a lip tip portion 17 that is substantially circular in radial cross-sectional view, and a lip base portion 16 that is provided so as to be connected to the lip tip portion 17 and is formed such that the dimensions in the direction perpendicular to the extension direction and circumferential direction of the lip portion 15 are smaller than those of the lip tip portion 17. With this configuration, compared to a configuration in which a tapered lip tip is brought into contact, even if there is eccentricity or inclination between the first member 2 and the second member 3, the lip base portion 16 is more easily deformed, which in turn allows the substantially circular circumferential surface 17a of the lip tip portion 17 to stably contact the second member 3. This makes it easier to maintain electrical conductivity between the first member 2 and the second member 3 over a long period of time.

[0013] As shown in Figures 1 and 2, the bearing device 1 comprises a first member 2 and a second member 3 that rotate axially relative to each other, and a sealing device 10 that seals the annular space S between them. The second member 3 is provided with a groove 3b for receiving the lip tip 17. With this configuration, the contact area with the lip tip 17 can be increased by the inner surface 3c of the groove 3b, thereby improving conductivity. A specific example of the configuration will be described below.

[0014] The bearing device 1 is configured such that, for example, a first member 2 constituting the outer member is fitted into a housing or the like, a shaft 5 is inserted through a second member 3 constituting the inner member, and the second member 3 is rotatable with respect to the first member 2 together with the shaft 5. The second member 3 is a cylindrical member that fits (externally fits) onto the shaft 5, and the first member 2 is a cylindrical member formed concentrically with the second member 3 and provided on the outer circumference at a distance from the second member 3. The bearing device 1 is configured to include a single row of rolling elements (balls) 4 interposed between the first member 2 and the second member 3. Within the annular space S, the single row of rolling elements 4 is interposed so as to be rotatable between the raceway rings of the first member 2 and the raceway rings of the second member 3, with the single row of rolling elements 4 held by a retainer (not shown). The bearing device 1 may also be configured to have grooved raceway rings on the first member 2 and the second member 3. The annular space S is filled with a filler such as grease to facilitate the rolling of the rolling elements 4. Sealing devices 10, 10, which are formed in an annular shape along the circumferential direction of the bearing device 1, are mounted on both axial ends of the annular space S. These sealing devices 10, 10 have substantially the same configuration.

[0015] The first member 2 is provided with grooves 2a formed on both axial sides of the inner circumferential surface 2e of the first member 2, extending around its entire circumference. The mounting portion 13 of the sealing device 10 is fitted into the grooves 2a. As shown in Figure 2, the grooves 2a are provided opening on the inner diameter side (second member side) and may be approximately rectangular in shape when viewed in the longitudinal direction of the groove, divided into a groove bottom 2b that is approximately parallel to the axial direction and groove walls 2c and 2d on both sides of the groove width direction of the groove 2a. The groove wall 2c on the outer space side of the groove walls 2c and 2d may have a smaller radial dimension than the groove wall 2d on the annular space S side. In such a case, the inner circumferential surface 2e of the first member 2 connected to the groove wall 2c on the outer space side is located on the outer diameter side than the inner circumferential surface 2e of the first member 2 connected to the groove wall 2d on the annular space S side.

[0016] The groove portion 3b is provided on both axial sides of the outer peripheral surface 3a of the second member 3 and is formed over the entire circumference of the second member 3. As shown in FIG. 2, the groove portion 3b may open to the outer diameter side (the first member 2 side) and may be formed in a concave curved shape in which the inner surface 3c is recessed toward the inner diameter side in a radial cross-sectional view. The inner surface 3c of the groove portion 3b may be formed in a shape corresponding to at least the circumferential surface 17a (outer contour shape) on the inner diameter side of the lip tip portion 17. Further, the groove portion 3b may be provided at a position radially overlapping the concave groove 2a of the first member 2. Note that the groove portion 3b is not limited to the above-described configuration, and for example, it may be formed in a substantially square groove shape when viewed in the groove length direction.

[0017] The sealing device 10 includes an annular core member 11. As shown in FIG. 2, the core member 11 includes a cylindrical portion 11a provided on the outer diameter side of the core member 11 and formed concentrically with the first member 2, and an annular portion 11b that continues from one axial side (outer space side) end of the cylindrical portion 11a and extends toward the inner diameter side. In the illustrated example, the core member 11 is formed such that the radial dimension of the annular portion 11b is larger than the axial dimension of the cylindrical portion 11a. The core member 11 may be formed by pressing a steel plate such as SPCC or SUS. Further, the core member 11 may have conductivity.

[0018] The seal portion 12 is fixed to the core member 11. The seal portion 12 is provided so as to connect the mounting portion 13 and the lip portion 15, and includes a seal annular portion 14 that covers the outer space side of the core member 11 to which the seal portion 12 is fixed. With such a configuration, compared with a configuration in which a through hole is provided in the conductive ring, the sealing performance can be improved by the mounting portion 13, the seal annular portion 14, and the lip portion 15 of the seal portion 12. Specifically, the seal portion 12 is fixed to the core member 11 so as to cover the entire annular space side end face and the entire outer peripheral surface of the cylindrical portion 11a, the entire outer space side surface and the entire inner diameter side end face of the annular portion 11b, and a part of the inner diameter side of the annular space side surface. In the seal portion 12, a portion fixed so as to cover the entire outer peripheral surface of the cylindrical portion 11a of the core member 11 is formed as the mounting portion 13. Further, in the seal portion 12, a portion fixed so as to cover the entire outer space side surface of the annular portion 11b of the core member 11 is formed as the seal annular portion 14. Further, the seal portion 12 is formed with a lip portion 15 extending inward from a portion covering the entire inner diameter side end face of the annular portion 11b. The seal portion 12 is formed of a rubber material having conductivity. Examples of the rubber material having conductivity include, but are not limited to, rubber materials mixed with conductive carbon fillers such as carbon black, carbon fiber, carbon nanofiber, and graphite. The seal portion 12 has the mounting portion 13, the seal annular portion 14, and the lip portion 15 connected in series. Thus, in the state where the sealing device 10 is mounted on the bearing device 1, the seal portion 12 abuts against the first member 2 and the second member 3, making the first member 2 and the second member 3 electrically conductive.

[0019] The mounting portion 13 is provided on the outer diameter side of the cylindrical portion 11a of the core member 11 and is formed to be fitted into the concave groove 2a of the first member 2. The mounting portion 13 is formed such that in the state of being fitted into the concave groove 2a, the outer diameter side end portion contacts the groove bottom 2b and elastically deform. The mounting portion 13 may be formed in a substantially trapezoidal shape that tapers as it goes toward the outer diameter side in the natural state before elastic deformation, with approximately half of the outer diameter side. Further, the mounting portion 13 is formed to abut (elastically abut) against the groove walls 2c, 2d of the concave groove 2a. Note that the mounting portion 13 is not limited to the above-described configuration. For example, the outer diameter side surface of the mounting portion 13 may be formed in an inclined shape.

[0020] The lip portion 15 is located on the inner diameter side of the annular portion 11b and is formed around the entire circumference of the core member 11. The lip portion 15 comprises a lip base end portion 16 provided on the base end side in the extension direction (the annular portion 11b side of the core member 11) and a lip tip portion 17 provided on the tip side in the extension direction of the lip base end portion 16. The lip base end portion 16 may be formed to incline toward the annular space S side as it extends toward the inner diameter. Furthermore, the dimension of the lip base end portion 16 in the extension direction is larger than the dimension in the direction perpendicular to the extension direction and the circumferential direction. The lip base end portion 16 only needs to be formed such that the dimension in the direction perpendicular to the extension direction and the circumferential direction is smaller than the radial dimension of the lip tip portion 17, for example, it may be 90% or less of the radial dimension of the lip tip portion 17.

[0021] The lip tip 17 has a circumferential surface 17a on the inner diameter side that corresponds to the inner surface 3c of the groove 3b. This effectively increases the contact area with the groove 3b and improves conductivity. In this embodiment, as shown in Figure 2, the lip tip 17 is configured such that the circumferential surface 17a on the inner diameter side can abut against substantially the entire inner surface 3c of the groove 3b. The radial dimension of the lip tip 17 in a radial cross-sectional view may be larger than the extension dimension of the lip base 16. In the illustrated example, the lip tip 17 is provided such that, in the natural state before elastic deformation of the lip base 16, the end on the external space side is located on the external space side of the groove 3b of the second member 3. In other words, the lip tip 17 is configured to be received by the groove 3b of the second member 3 by elastically deforming the lip base 16. The lip tip portion 17 is provided such that its approximate axial center on the outer diameter side circumferential surface 17a connects to the extending tip portion of the lip base portion 16. The lip tip portion 17 only needs to have a substantially circular shape in its radial cross-sectional view; for example, it may be shaped to abut a part of the inner surface 3c of the groove portion 3b.

[0022] In the sealing device 10, in its natural state before the elastic deformation of the sealing portion 12, the distance from the outer diameter side tip of the mounting portion 13 to the inner diameter side tip of the lip tip portion 17 is greater than the distance from the groove bottom 2b of the recessed groove 2a of the first member 2 to the bottom of the groove portion 3b of the second member 3. When the mounting portion 13 is elastically deformed and fitted into the recessed groove 2a of the first member 2, the lip base portion 16 is elastically deformed so that the lip tip portion 17 is received into the groove portion 3b of the second member 3, and the lip tip portion 17 elastically contacts the inner surface 3c of the groove portion 3b. In this state, if the lip base portion 16 is elastically deformed to bend toward the annular space S, the lip base portion 16, attempting to restore to its original shape, presses the lip tip portion 17 against the inner surface 3c of the groove portion 3b of the second member 3, thereby enabling more stable contact between the lip tip portion 17 and the second member 3. Furthermore, the configuration is not limited to one in which the lip tip 17 is received in the groove 3b while the lip base 16 is elastically deformed to bend. The mounting portion 13 may be fitted into the recessed groove 2a, and the lip tip 17 may be received in the groove 3b without the lip base 16 undergoing any significant elastic deformation.

[0023] Next, we will describe each modified example with reference to Figures 3 and 4. In the following descriptions of each modified example, we will mainly explain the differences from the previously described example, and will omit or briefly explain similar configurations or similar effects.

[0024] Figure 3 schematically shows a modified bearing device 1A. In this modified example, the configuration of the second member 3A differs from the previous example. In this modified example, the circumferential surface (outer surface 3a in the figure) of the second member 3A, from the axial end on the external space side to the contact surface where the lip tip 17 elastically contacts, is formed in a cylindrical shape. In other words, the second member 3A is not provided with a groove 3b for receiving the lip tip 17. With this configuration, the sealing device 10 can be assembled to the bearing device 1A more smoothly compared to a configuration in which the outer surface 3a of the second member 3 has irregularities or the like.

[0025] The radial dimension of the sealing portion 12 in the sealing device 10 in its natural state before elastic deformation is set to be larger than the dimension from the groove bottom 2b of the groove 2a of the first member 2 to the outer circumferential surface 3a (contact surface) of the second member 3. The lip tip 17 elastically contacts the outer circumferential surface 3a of the second member 3, causing the lip base portion 16 to bend toward the annular space S, similar to the above configuration. In addition, the contact portion of the lip tip 17 with the outer circumferential surface 3a of the second member 3 presses against the outer circumferential surface 3a and undergoes elastic deformation. With this configuration, the contact area with the outer circumferential surface 3a of the second member 3 is larger compared to a configuration in which the contact portion with the outer circumferential surface 3a of the second member 3 does not undergo elastic deformation, thereby improving conductivity.

[0026] Figure 4(a) schematically shows a modified sealing device 10A. In this modified example, the lip tip 17 has a plurality of protrusions 18 that protrude from the circumferential surface 17a and contact the second member 3. With this configuration, the protrusions 18 of the lip tip 17 can effectively increase the contact pressure with the second member 3, thereby further improving conductivity. Specifically, the protrusion 18 is provided projecting from the inner diameter side circumferential surface 17a of the lip tip 17. The inner diameter side circumferential surface 17a of the lip tip 17 is formed in an arc shape that is convex inward when viewed in a radial cross-section. The protrusion 18 extends around the entire circumference of the lip tip 17 and is formed as a continuous annular protrusion along the circumferential direction of the lip tip 17. When viewed in a radial cross-section, the protrusion 18 is formed in a substantially semicircular shape. Multiple protrusions 18 (three in the illustrated example) are provided side by side in the axial direction. Note that the protrusion 18 is not limited to a continuous annular protrusion along the circumferential direction, but may be formed as an intermittent projection along the circumferential direction.

[0027] The sealing device 10A according to this modified example may be mounted on a bearing device 1 that has a second member 3 having a groove 3b that receives the lip tip 17 and has an inner surface 3c into which a plurality of protrusions 18 make contact, as shown in Figure 4(b). The groove 3b may have a configuration similar to the previous example shown in Figure 2, which opens on the outer diameter side and has a concave curved inner surface 3c that is recessed on the inner diameter side in a radial cross-sectional view. If the protrusions 18 are elastically deformed upon contact with the inner surface 3c of the groove 3b, the contact area with the inner surface 3c of the groove 3b becomes larger compared to a configuration in which the protrusions 18 are not elastically deformed, thereby improving conductivity. Alternatively, the sealing device 10A according to this modified example may be mounted on a bearing device 1A that has a second member 3A without a groove 3b, as shown in Figure 3. In such a case, the protrusions 18 contact the outer circumferential surface 3a of the second member 3A and undergo elastic deformation.

[0028] The configurations of the sealing devices described in the above embodiments and their respective modifications may be modified, rearranged, or combined as appropriate and necessary. Furthermore, the components are not limited to the configurations described above. For example, multiple hemispherical recesses may be provided on the contact surface between the lip tip and the groove of the second component. In such a case, lubricant can be stored in the recesses at the lip tip to improve lubrication performance. Furthermore, the configurations of the different bearing devices described in the above embodiments and their respective modifications may be modified, rearranged, or combined as appropriate and necessary. Also, the components are not limited to the above-described configurations. For example, the bearing device may have a configuration in which the outer member (first member) rotates. Alternatively, the bearing device may have a configuration in which a mounting portion for a sealing device is attached to the inner member, and a lip portion elastically contacts the outer member. In such cases, a groove portion for receiving the tip of the lip portion may be provided on the inner circumferential surface of the outer member. [Explanation of symbols]

[0029] 1.1A Bearing device 2. First Member 3,3A Second member 3b Groove 3c Inner surface 10,10A sealing device 11 Core member 12. Seal part 13 Mounting part 14. Seal ring portion 15 Lip section 16 Lip base 17 Lip tip 17a Circumferential surface 18 Convex part S-shaped circular space

Claims

1. A sealing device for sealing an annular space between a first member and a second member that rotate relatively on an axis, It has a mounting portion that is attached to the first member and a lip portion that extends toward the second member and elastically contacts the second member, and is equipped with a conductive sealing portion that electrically connects the first member and the second member, The sealing device is characterized in that the lip portion comprises a lip tip portion which is substantially circular in a radial cross-sectional view, and a lip base portion which is provided so as to be connected to the lip tip portion and is formed such that the dimensions in the direction perpendicular to the extension direction and circumferential direction of the lip portion are smaller than those of the lip tip portion.

2. In claim 1, The sealing device is characterized in that the sealing portion is provided to connect the mounting portion and the lip portion, and includes a sealing ring portion that covers the external space side of the core member to which the sealing portion is fixed.

3. In claim 1 or claim 2, The sealing device is characterized in that the tip of the lip has a plurality of protrusions that protrude from the circumferential surface and contact the second member.

4. The device comprises a first member and a second member that rotate on an axis relative to each other, and a sealing device according to claim 1 or claim 2 that seals the annular space between them. The bearing device is characterized in that the second member is provided with a groove for receiving the tip of the lip.

5. The device comprises a first member and a second member that rotate on an axis relative to each other, and a sealing device according to claim 3 that seals the annular space between them. The bearing device is characterized in that the second member is provided with a groove having an inner surface that receives the tip of the lip and into contact with the plurality of protrusions.

6. The device comprises a first member and a second member that rotate on an axis relative to each other, and a sealing device according to claim 1 or claim 2 that seals the annular space between them. The bearing device is characterized in that the circumferential surface of the second member, from the axial end on the external space side to the contact surface to which the lip tip elastically makes contact, is formed in a cylindrical shape.

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