SEALING DEVICE

A sealing device includes a conductive member integrated with a seal lip along a circumferential direction of the seal lip and configured such that a voltage is applied to the conductive member, and a reference member provided at a predetermined interval with respect to the conductive member. A deformation degree of the seal lip is inspected such that a change of an inductance of the conductive member associated with a change of the interval between the conductive member and the reference member is detected by a detection unit.

INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application No. 2017-054627 filed on Mar. 21, 2017 and Japanese Patent Application No. 2017-054866 filed on Mar. 21, 2017, each including the specification, drawings and abstract, is incorporated herein by reference in its entirety.

BACKGROUND

1. Technical Field

The disclosure relates to a sealing device.

2. Description of Related Art

A sealing device is used for a rotational member in an industrial product or an industrial machine, in order to prevent an invasion of a foreign matter into a space between a rotating shaft and a housing and an outflow of a lubricant such as grease. An example of the sealing device is a sealing device including a seal lip that slidably makes close contact with a rotating shaft. An oil seal has been widely used as such a sealing device.

SUMMARY

When a sealing surface on an inner periphery of the seal lip makes close contact with an abutting surface of a rotating shaft, the sealing surface slides with respect to the rotating shaft. The sealing surface is gradually worn out by friction. The seal lip gradually deforms in the direction approaching the rotating shaft along with the wearing-out. When the seal lip deforms by a predetermined amount due to the wearing-out of the sealing surface, a contact pressure between the sealing surface and the rotating shaft becomes insufficient, so that seal performance is decreased, thereby causing an invasion of a foreign matter into an annular space or an outflow of a lubricant to outside the annular space.

Generally, this problem can be solved by replacing the sealing device regularly. That is, the replacement of the sealing device is performed at an interval shorter than a period during which the seal performance is decreased, so as to prevent the invasion of a foreign matter into the rotational member and the outflow of the lubricant. However, in such a method, a replacement cycle of the sealing device is short, so that it takes time to perform maintenance of the sealing device. Further, if an abnormal deformation occurs in the seal lip before a predetermined replacement timing comes, it is difficult to restrain the invasion of a foreign matter into the annular space and the outflow of the lubricant to outside the annular space.

In view of this, it is conceivable to inspect a deformation degree of the seal lip, i.e., whether or not the deformation reaches a predetermined amount, by using an inspection apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2014-74469 (JP 2014-74469 A). The inspection apparatus disclosed in JP 2014-74469 A is configured to detect whether or not a garter spring is attached to a prescribed position of a seal lip of an oil seal by fitting the oil seal to the inspection apparatus. When the seal lip deforms, a position at which the garter spring is attached also changes. Accordingly, it is presumably possible to inspect whether or not the seal lip has deformed at the predetermined amount, by detecting whether or not the position at which the garter spring is attached changes from a predetermined position by the predetermined amount, by using the inspection apparatus disclosed in JP 2014-74469 A.

However, in a case where the inspection is performed by using the inspection apparatus disclosed in JP 2014-74469 A, it is necessary to stop an operation of the rotational member and remove the oil seal, and to fit the oil seal to the inspection apparatus. This accordingly decreases operation efficiency of the rotational member.

The present disclosure is accomplished in view of such a problem, and an object of the present disclosure is to provide a sealing device including a seal lip having a sealing surface making close contact with a rotating shaft of a rotational member, the sealing device being able to inspect a deformation degree of a seal lip, caused due to wearing-out of the sealing surface without decreasing operation efficiency of the rotational member.

An aspect of the present disclosure is related to a sealing device provided radially inward of an inner peripheral surface of an outer member. The sealing device includes an attachment portion having an annular shape and attached to the outer member, a seal lip having an annular shape and being fixed to the attachment portion and having a sealing surface in an inner peripheral part of the seal lip, the sealing surface making contact with a shaft provided radially inward of the inner peripheral surface of the outer member. The sealing device also includes a conductive member integrated with the seal lip along a circumferential direction of the seal lip, the conductive member being configured such that a voltage is applied to the conductive member. The sealing device also includes a reference member placed so that a predetermined interval is provided between the conductive member and the reference member. The sealing device also includes a detection unit. The detection unit detects a change of an inductance of the conductive member associated with a change of the interval between the conductive member and the reference member.

In the above aspect of the present disclosure, the reference member may be a member having conductivity and provided in the seal lip or the attachment portion in a state where the member is distanced from the conductive member at the predetermined interval.

With the sealing device, when the seal lip deforms associated with wearing-out of the sealing surface, the interval between the conductive member and the reference member (the member having conductivity) changes. Further, the conductive member functions as a magnetic sensor when a voltage is applied to the conductive member. Because of this, the change of the interval between the conductive member and the reference member as a sensing target is detected as a change of the inductance of the conductive member. Hereby, it is possible to inspect a deformation degree of the seal lip by an easy configuration. Further, the deformation degree of the seal lip can be inspected even while a rotational member to which the sealing device is attached is rotating. Hereby, the deformation degree of the seal lip can be inspected without reducing operation efficiency.

The conductive member may be provided annularly along the circumferential direction of the seal lip so as to be concentric to the seal lip. The reference member may be provided annularly along the circumferential direction of the seal lip so as to be concentric to the seal lip.

With the sealing device, the deformation of the seal lip is sensed over its entire circumference. As a result, it is possible to improve inspection accuracy of the deformation degree of the seal lip.

The conductive member and the reference member may be annular metal wires placed in the seal lip. A diameter of section of each of the annular metal wires may be equal to or smaller than a predetermined diameter.

In a case where the conductive member and the reference member are bold metal wires, deformation of the seal lip is disturbed by their rigidities. As a result, the deformation degree of the seal lip cannot be inspected accurately. In contrast, when the metal wire having a section with a diameter that is the predetermined diameter or less is used as the conductive member and the reference member, a possibility to disturb the deformation of the seal lip associated with wearing-out of the sealing surface is low because the rigidity of the metal wire is low. This makes it is possible to inspect the deformation degree of the seal lip with high accuracy.

The reference member may be a core member provided in the attachment portion. The reference member may be an annular spring configured to tighten an inner periphery of the seal lip to the shaft.

When the member having conductivity and constituting the sealing device doubles as the reference member, the number of components to be placed in the sealing device can be restrained. This makes it possible to easily manufacture the sealing device.

The core member may have an L-shaped section with one side facing the seal lip. The detection unit may be placed on an inner surface of the core member.

When the detection unit is provided by effectively using a space in the sealing device as such, it is possible to restrain upsizing of the sealing device.

A voltage may be applied to the reference member.

With the sealing device, a magnetic field is also generated around the reference member, thereby making it possible to increase its influence on the magnetic field around the conductive member. That is, it is possible to largely change magnetic resistance around the conductive member at the time when the interval between the conductive member and the reference member changes. As a result, the deformation degree of the seal lip can be inspected more accurately.

In the foregoing aspect of the present disclosure, the reference member may be the shaft.

With the sealing device having such a structure, when the seal lip deforms along with wearing-out of the sealing surface, an interval between the conductive member and the reference member (a shaft) changes. Further, the conductive member functions as a magnetic sensor when a voltage is applied to the conductive member. Because of this, a change of the interval between the conductive member and the reference member as a sensing target is detected as a change of the inductance of the conductive member. Hereby, it is possible to inspect the deformation degree of the seal lip by an easy configuration. Further, the deformation degree of the seal lip can be inspected even while the rotational member to which the sealing device is attached is rotating. Hereby, the deformation degree of the seal lip can be inspected without reducing operation efficiency.

The conductive member may be provided annularly along the circumferential direction of the seal lip so as to be concentric to the seal lip.

With the sealing device, the deformation of the seal lip is sensed over its entire circumference. As a result, it is possible to improve inspection accuracy of the deformation degree of the seal lip.

The conductive member may be an annular metal wire placed in the seal lip. A diameter of a section of the annular metal wire may be equal to or smaller than a predetermined diameter.

In a case where the conductive member is a bold metal wire, the deformation of the seal lip is disturbed by its rigidity. As a result, the deformation degree of the seal lip cannot be inspected accurately. In contrast, when the metal wire having a section with a diameter that is the predetermined diameter or less is used as the conductive member, a possibility to disturb deformation of the seal lip associated with wearing-out of the sealing surface is low because the rigidity of the metal wire is low. This makes it is possible to inspect the deformation degree with high accuracy.

The attachment portion may be provided with a core member, the core member having an L-shaped section with one side facing the seal lip. The detection unit may be placed on an inner surface of the core member.

When the detection unit is provided by effectively using a space in the sealing device as such, it is possible to restrain upsizing of the sealing device.

The detection unit may be configured to output a result detected by the detection unit.

Hereby, it is possible to easily find an inspection result.

The detection unit may be configured to output the result when the change of the inductance of the conductive member is larger than a predetermined threshold.

With the sealing device, when the predetermined threshold is set to a change value of the inductance at the time when the inductance decreases to around a value at which the seal performance of the sealing device is impaired, it is possible to easily find that the sealing device nears its use limit.

With the present disclosure, in terms of a sealing device including a seal lip having a sealing surface making close contact with a rotating shaft, it is possible to inspect a deformation degree of the seal lip caused due to wearing-out of the sealing surface without reducing operation efficiency of a rotational member.

DETAILED DESCRIPTION OF EMBODIMENTS

With reference to the drawings, the following describes embodiments of the present disclosure. In the following description, identical components or constituents have the same reference sign. They also have the same name and function. Accordingly, their detailed descriptions are not repeated herein.

A sealing device10according to a first embodiment of the present disclosure is an oil seal as an example.FIG. 1is a sectional view of the sealing device10. The sealing device10is provided together with a rolling bearing (not shown) configured to support a shaft5with respect to a housing6. The housing6has a cylindrical inner peripheral surface6a. An annular space4is formed radially inward of the cylindrical inner peripheral surface6a, between the housing6and the shaft5. The rolling bearing is provided at a predetermined position in the annular space4, and respective sealing devices10are provided on the opposite sides of the rolling bearing in an axial direction. The shaft5is a rotatable rotating shaft, for example. The housing6corresponds to an example of an “outer member” in the present disclosure.

The shaft5is made of a soft magnetic material. The soft magnetic material is iron, for example. The shaft5is assembled concentrically to the cylindrical inner peripheral surface6aof the housing6. The sealing device10has an annular shape and is attached to the annular space4so as to be concentric to the shaft5.

The sealing device10includes an annular attachment portion12attached to the housing6, and an annular seal body20integrated with the attachment portion12. A sectional shape of the attachment portion12has an L-shape constituted by a cylindrical portion12amaking contact with the cylindrical inner peripheral surface6aso as to extend in the axial direction of the shaft5, and an annular portion12bextending in a radial direction from the cylindrical inner peripheral surface6atoward the shaft5.

The seal body20includes a fixed portion21and a seal lip24. The fixed portion21is a part fixed to an inner peripheral part of the annular portion12bof the attachment portion12. The seal lip24includes a lip head portion23and a lip base portion22. The lip head portion23includes an annular sealing surface23aformed in its inner periphery so as to make contact with the shaft5. The lip base portion22is a part configured to connect the fixed portion21to the lip head portion23.

The seal lip24extends from the fixed portion21as a base end toward a first side (the left side inFIG. 1) in the axial direction. The cylindrical portion12aof the attachment portion12faces the seal lip24in the radial direction. An outer peripheral surface26and an inner peripheral surface27of the lip base portion22have a tapered shape reduced in diameter toward the lip head portion23side.

The seal body20may further include an auxiliary lip29. The auxiliary lip29extends from the fixed portion21toward a second side in the axial direction.

The attachment portion12includes a rubber part12cas an external surface, and an annular core member11with which the rubber part12cis integrated by adhesion by vulcanization. The rubber part12cis integrated with the seal body20, and is made of rubber (elastomer), such as NBR, FKM, and ACM. The core member11is provided concentrically to the attachment portion12. The core member11is made of metal, such as stainless steel. A sectional shape of the core member11also has an L-shape one side of which faces the seal lip24, and is constituted by a cylindrical portion11aextending in the axial direction of the shaft5, and an annular portion11bextending in the radial direction from the cylindrical inner peripheral surface6atoward the shaft5.

The sealing device10further includes an annular spring (garter spring)19. The spring19tightens the lip head portion23to the shaft5. The spring19is attached to an outer peripheral part of the lip head portion23.

When the sealing device10is attached to the annular space4, the sealing surface23aof the lip head portion23makes contact with the shaft5. When the shaft5rotates in a state where the sealing device10is attached to the annular space4, the sealing surface23aslides over the shaft5. Hereby, sliding friction occurs on the sealing surface23a.

When the sliding friction occurs on the sealing surface23a, the sealing surface23ais worn out. When the sealing surface23ais worn out, the whole seal lip24deforms towards the shaft5side. Since the lip head portion23is tightened to the shaft5by the spring19, the whole seal lip24easily deforms due to the wearing-out of the sealing surface23a. When the seal lip24deforms by a predetermined amount or more, a contact pressure of the sealing surface23ato the shaft5decreases, so that seal performance of the sealing device10is decreased.

In view of this, in order to prevent the decrease of the seal performance, the sealing device10has a function to inspect a deformation degree, i.e., whether or not the deformation of the seal lip24reaches the predetermined amount. As a constituent to implement the function to inspect the deformation degree of the seal lip24, the sealing device10includes a first conductive member31functioning as a magnetic sensor, a second conductive member32as a sensing target for the first conductive member31, and a detection unit50. The first conductive member31corresponds to an example of a “conductive member” in the present disclosure. The second conductive member32corresponds to an example of a “reference member” in the present disclosure.

The first conductive member31is a metal member having conductivity, and preferably a linear or filament-shaped thin line (metal thin line) made of a metal material, such as copper. In the present embodiment, a metal thin line having a diameter of around 15 μm to 100 μm is used as the first conductive member31. If a bold metal wire is used as the first conductive member31, the deformation of the seal lip24is disturbed by its rigidity. As a result, the deformation degree of the seal lip24cannot be inspected accurately. In contrast, when a metal thin line is used as the first conductive member31, it is possible to prevent the deformation of the seal lip24from being disturbed, because its rigidity is low. This makes it possible to improve inspection accuracy of the deformation degree of the seal lip24.

The first conductive member31is integrated with the seal lip24. To be integrated refers to a state where the first conductive member31is provided so as to behave (deform) along with the behavior (deformation) of the seal lip24, and indicates a state where the first conductive member31is embedded in the seal lip24, a state where the first conductive member31is attached on a surface of the seal lip24, and the like state, for example. The first conductive member31is placed at a position where the first conductive member31does not make contact with the shaft5within the seal lip24or on the surface of the seal lip24, for example. Preferably, the first conductive member31is placed at a position where the seal lip24largely deforms due to the wearing-out of the sealing surface23a. As an example, the first conductive member31is placed near the spring19in the lip head portion23. This makes it possible to inspect the deformation degree of the seal lip24with high accuracy.

The first conductive member31is an annular member and is provided in an annular shape along a circumferential direction of the seal lip24so as to be concentric to the seal lip24. In the present embodiment, an annular metal thin line is embedded near the spring19so as to be concentric to the seal lip24. Hereby, the deformation of the seal lip24is sensed over its entire circumference. This makes it possible to improve the inspection accuracy of the deformation degree of the seal lip24.

In order that the first conductive member31functions as the magnetic sensor, a power source60(not shown inFIG. 1) is connected to the first conductive member31, so that a voltage is applied thereto. In a case where the first conductive member31is a linear member, the power source60is an alternating-current power source and applies an alternating voltage to the first conductive member31. In a case where the first conductive member31has a coil shape, the power source60is a direct-current power source and applies a direct voltage to the first conductive member31. Hereby, an inductance circuit including the first conductive member31is formed.

The second conductive member32is also a metal member having conductivity, and preferably a metal thin line made of a metal material, such as copper. This makes it possible to prevent the deformation of the seal lip24due to the wearing-out of the sealing surface23afrom being disturbed, for the same reason as above. This makes it possible to improve the inspection accuracy of the deformation degree of the seal lip24.

The second conductive member32is provided in the seal lip24or the attachment portion12in a state where the second conductive member32is distanced from the first conductive member31at a predetermined interval. As an example, the second conductive member32is placed within the seal lip24or on the surface of the seal lip24. The second conductive member32is an annular member and is provided along the circumferential direction of the seal lip24so as to be concentric to the seal lip24.

In the present embodiment, as illustrated inFIG. 1, the second conductive member32is embedded on a side closer to the fixed portion21than the position of the first conductive member31, so as to be concentric to the seal lip24. More specifically, in the present embodiment, the first conductive member31is placed near the spring19and the second conductive member32is placed on the side closer to the fixed portion21than the position of the first conductive member31so as to be distanced from the first conductive member31. With such an arrangement, the first conductive member31deforms more largely than displacement of the second conductive member32at the time when the seal lip24deforms due to the wearing-out of the sealing surface23a. This makes it possible to inspect the deformation degree of the seal lip24according to a detection principle that will be described later. Further, by placing the second conductive member32near the first conductive member31, it is possible to improve the inspection accuracy of the deformation degree of the seal lip24.

FIG. 2is a schematic diagram of the inductance circuit including the first conductive member31. With reference toFIG. 2, a measuring device40configured to measure an inductance is connected to the first conductive member31. The measuring device40is an LCR meter, for example.

Preferably, the measuring device40and the power source60are placed in the sealing device10. As an example, the measuring device40and the power source60are attached to an inner surface of the core member11having an L-shaped section. When the measuring device40and the power source60are provided by effectively using a space in the sealing device10, it is possible to restrain upsizing of the sealing device10.

The detection unit50includes one or more central processing units (CPU) and memories (both not shown). When the CPU executes a program stored in the memory, the detection unit50executes a process of detecting deformation of the seal lip24.

FIG. 3is a block diagram indicative of a functional configuration of the detection unit50. With reference toFIG. 3, the detection unit50is connected to the measuring device40via a signal wire (not shown), so as to receive a measured value of the inductance from the measuring device40. The detection unit50includes a detection control portion51configured to execute the process of detecting the deformation of the seal lip24by using the measured value of the inductance, and an output control portion52configured to control an output based on a detected result. The functions are implemented mainly by the CPU (not shown) of the detection unit50such that the CPU executes programs stored in the memory.

The power source60may be further connected to the detection unit50so as to supply electric power to the detection unit50. Furthermore, the power source60may supply electric power to the first conductive member31via the detection unit50. At this time, the detection unit50may further include an electric power controlling portion configured to control power supply from the power source60to the first conductive member31. Electric power may be supplied to the detection unit50from a power source different from the power source60.

Preferably, the detection unit50is placed in the sealing device10. More specifically, the detection unit50is attached to a surface of the sealing device10. More preferably, the detection unit50is attached to the inner surface of the core member11having an L-shaped section. The inner surface of the core member11is a side surface facing the seal lip24. More specifically, the inner surface of the core member11is a surface of the cylindrical portion11afacing the seal lip24, or a surface of the annular portion11bon a side where the seal lip24extends. When the detection unit50is provided by effectively utilizing the space of the sealing device10, it is possible to restrain upsizing of the sealing device10. In the present embodiment, the detection unit50is attached to the surface of the cylindrical portion11afacing the seal lip24.

The detection unit50may be placed outside the sealing device10. In this case, the detection unit50preferably communicates wirelessly with the measuring device40. Note that the configuration in which the detection unit50is placed outside the sealing device10and communicates wirelessly with the measuring device40is also included in a state where the detection unit50is provided in the sealing device10.

Preferably, the measuring device40and the power source60are placed near the detection unit50. The measuring device40and the power source60may be included in the detection unit50. Hereby, the measuring device40and the power source60are easily connected to the first conductive member31forming the inductance circuit inFIG. 2, and are also easily connected to the detection unit50.

Further, the power source60may have a power generation function. This makes it possible to eliminate the need for power supply to the detection unit50and the first conductive member31from outside. Note that the power source60may be placed outside the sealing device10so as to supply electric power to the detection unit50and the first conductive member31via a power line (not shown) or wireless communication.

FIG. 4is a view to describe a principle to detect deformation of the seal lip24. InFIG. 4, the seal lip24is indicated by a continuous line and an alternate long and two short dashes line. The seal lip24in the continuous line indicates a state before the sealing surface23ais worn out. The seal lip24in the alternate long and two short dashes line indicates a state where the sealing surface23ahas been worn out.

With reference toFIG. 4, when the sealing surface23ais worn out, the seal lip24deforms toward the shaft5side, starting from the fixed portion21. Due to the deformation of the seal lip24, an interval between the first conductive member31and the second conductive member32changes from an interval d1to an interval d2.

Since a voltage is applied to the first conductive member31, a magnetic field is generated around the first conductive member31. When the interval (distance) between the first conductive member31and the second conductive member32changes, magnetic resistance around the first conductive member31changes. Hereby, the inductance of the first conductive member31changes. That is, a change of the interval between the first conductive member31and the second conductive member32can be detected as a change of the inductance of the first conductive member31.

An initial value of the inductance of the first conductive member31before the sealing surface23ais worn out is stored in the detection control portion51. The initial value may be a measured value of the inductance of the first conductive member31just after the first conductive member31is attached to the sealing device10. Alternatively, a set initial value may be stored in the detection control portion51in advance. The detection control portion51obtains a change amount in measured value by calculating a difference between the initial value and a measurement result by the measuring device40.

A magnitude of the change of the inductance of the first conductive member31depends on a change amount |d1−d2| of the interval between the first conductive member31and the second conductive member32. That is, when the change amount |d1−d2| is large, the change amount of the inductance of the first conductive member31is large. In view of this, the detection control portion51is configured such that a change value of the inductance at the time when the inductance decreases to around a value at which the seal performance of the sealing device10is impaired is stored in the detection control portion51in advance as a threshold, so that the detection control portion51determines whether or not a change amount of a measured value, that is, a change of the inductance of the first conductive member31exceeds the threshold. A case where the change of the inductance exceeds the threshold indicates a state just before the seal performance of the sealing device10is impaired, that is, a state where the sealing device10almost reaches its use limit. The threshold is found in advance by experiment.

The detection control portion51inputs a determination result into the output control portion52. The output control portion52is connected to an output device (not shown). The output control portion52outputs an inspection result based on the determination result from the output device. Hereby, it is possible to easily find an inspection result of the deformation degree of the seal lip24.

Preferably, the output control portion52outputs the inspection result based on the determination result when the change of the inductance is larger than the threshold. The output device is a radio transmitter or an audio output device (a speaker), for example. Hereby, it is possible to easily find that the inspection result indicates that the seal lip24has deformed to such a degree that the seal performance of the sealing device10is impaired, that is, the sealing device10has reached its use limit.

Note that the first conductive member31and the second conductive member32are placed in the seal lip24, so that an interval therebetween is small. Particularly, when the first conductive member31and the second conductive member32are embedded in the seal lip24as illustrated inFIG. 1, the interval therebetween is very small. On that account, the change amount |d1−d2| of the interval due to the deformation of the seal lip24is also very small. As a result, the change of the inductance is also very small. Because of this, it might be difficult to inspect the deformation degree of the seal lip24based on the change of the inductance, in some cases.

In view of this, preferably, the sealing device10is configured such that a voltage is also applied to the second conductive member32, so as to generate a magnetic field around the second conductive member32. On that account, the second conductive member32is also connected to a power source (not shown). As the power source, the power source60for the first conductive member31may be used in common. When the second conductive member32is a metal wire, an alternating-current power source is connected to the second conductive member32, so as to apply an alternating voltage thereto.

By generating the magnetic field around the second conductive member32, it is possible to increase an influence on the magnetic field around the first conductive member31as compared with a case where the magnetic field is not generated around the second conductive member32. That is, by generating the magnetic field around the second conductive member32, it is possible to more largely change magnetic resistance around the first conductive member31at the time when the interval between the first conductive member31and the second conductive member32changes. As a result, the change of the interval between the first conductive member31and the second conductive member32, that is, the deformation degree of the seal lip24can be inspected with higher accuracy.

FIG. 5is a flowchart illustrating a flow of an operation of the sealing device10to inspect the deformation degree of the seal lip24. The flowchart ofFIG. 5indicates an inspection method for inspecting the deformation degree of the seal lip24in the sealing device10.

With reference toFIG. 5, in the sealing device10, an inductance L of the first conductive member31is measured by the measuring device40at a predetermined timing (step S101). The predetermined timing is, for example, a timing determined in advance (e.g., a rotation start timing, a timing after a predetermined time elapses from the rotation start, and the like), a predetermined interval, and the like.

The detection control portion51calculates a change ΔL from an initial value of the inductance L and compares it with the threshold TH. When the change ΔL of the inductance is larger than the threshold TH (YES in step S103), the detection control portion51outputs a detection signal to the output control portion52(step S105). The output control portion52outputs a determination result in the detection control portion51using an output device (not shown) such as a radio transmitter.

Thus, the sealing device10according to the first embodiment of the present disclosure is configured such that: the sealing device10employs the first conductive member and the second conductive member provided in the seal lip24or the attachment portion12so as to be distanced from each other at a predetermined interval; and the sealing device10uses one of the first conductive member and the second conductive member as a magnetic sensor, so as to inspect the deformation degree of the seal lip24as a change of an interval between the first conductive member and the second conductive member based on a change of an inductance. Accordingly, it is possible to inspect the deformation degree of the seal lip24with high accuracy by a simple configuration. Further, even during rotation of the rolling bearing, it is possible to inspect the deformation degree of the seal lip24. Hereby, the deformation degree of the seal lip24can be inspected without reducing operation efficiency of the rolling bearing.

By setting the threshold to an appropriate value, it is possible to find a timing to replace the seal lip24before the seal performance of the sealing device10is impaired. As a result, the sealing device10can be replaced before the seal performance of the sealing device10is impaired to cause an invasion of a foreign matter into the annular space or an outflow of the lubricant to outside the annular space. Further, by setting the threshold to an appropriate value, a replacement cycle of the sealing device can be set to an appropriate cycle according to a degree of the wearing-out of the sealing surface23a.

Note that a magnitude of the change of the inductance of the first conductive member31depends on not only the change amount |d1−d2| of the interval between the first conductive member31and the second conductive member32, but also a change amount of an interval between the first conductive member31and the shaft5. The following describes a second embodiment of the present disclosure. In the second embodiment, the same constituent as in the first embodiment has the same reference sign as in the first embodiment, and a description thereof is omitted.

A sealing device10according to the second embodiment of the present disclosure is an oil seal, for example.FIG. 6is a sectional view of the sealing device10. Differently from the first embodiment of the present disclosure, the sealing device10according to the second embodiment of the present disclosure does not include the second conductive member32. On this account, inFIG. 7that is a schematic view of an inductance circuit according to the second embodiment of the present disclosure, the second conductive member32is not illustrated. Further, the configuration of the detection unit50of the second embodiment of the present disclosure is the same as the configuration of the detection unit50of the first embodiment of the present disclosure as illustrated inFIG. 3.

FIG. 8is a view to describe a principle to detect deformation of the seal lip24of the second embodiment of the present disclosure. InFIG. 8, the seal lip24is indicated by a continuous line and an alternate long and two short dashes line. The seal lip24in the continuous line indicates a state before the sealing surface23ais worn out. The seal lip24in the alternate long and two short dashes line indicates a state where the sealing surface23ahas been worn out.

Referring toFIG. 8, when the sealing surface23ais worn out, the seal lip24deforms toward the shaft5side, starting from the fixed portion21. Due to the deformation of the seal lip24, the interval between the first conductive member31and the shaft5is decreased by a distance d.

Since a voltage is applied to the first conductive member31, a magnetic field is generated around the first conductive member31. When the interval (distance) between the first conductive member31and the shaft5changes, magnetic resistance around the first conductive member31changes. Hereby, an inductance of the first conductive member31changes. That is, a change of the interval between the first conductive member31and the shaft5can be detected as a change of the inductance of the first conductive member31. Here, the shaft5corresponds to an example of a “reference member” in the present disclosure.

An initial value of the inductance of the first conductive member31before the sealing surface23ais worn out is stored in the detection control portion51. The initial value may be a measured value of the inductance of the first conductive member31just after the first conductive member31is attached to the sealing device10. Alternatively, a set initial value may be stored in the detection control portion51in advance. The detection control portion51obtains a change amount of the measured value by calculating a difference between the initial value and a measurement result by the measuring device40.

A magnitude of the change of the inductance of the first conductive member31depends on a change amount d of the interval between the first conductive member31and the shaft5. That is, when the change amount d is large, the change amount of the inductance of the first conductive member31is large. In view of this, the detection control portion51is configured such that a change value of the inductance at the time when the inductance decreases to around a value at which the seal performance of the sealing device10is impaired is stored therein in advance as a threshold, so that the detection control portion51determines whether or not a change amount of a measured value, that is, a change of the inductance of the first conductive member31exceeds the threshold. A case where the change of the inductance exceeds the threshold indicates a state just before the seal performance of the sealing device10is impaired, that is, a state where the sealing device10almost reaches its use limit. The threshold is found in advance by experiment.

Particularly, since the shaft5is a soft magnetic material, a magnetic field is generated around the shaft5by rotating. On this account, when the interval between the first conductive member31and the shaft5changes due to the deformation of the seal lip24, magnetic resistance around the first conductive member31more largely changes. As a result, the change of the interval between the first conductive member31and the shaft5, that is, the deformation degree of the seal lip24can be inspected with higher accuracy.

The detection control portion51inputs a determination result into the output control portion52. The output control portion52is connected to an output device (not shown). The output control portion52outputs an inspection result based on the determination result from the output device. Hereby, it is possible to easily find the inspection result of the deformation degree of the seal lip24. Further, in the second embodiment, the operation of the sealing device10to inspect the deformation degree of the seal lip24is the same as the operation of the sealing device10according to the first embodiment as illustrated inFIG. 5.

Thus, the sealing device10according to the second embodiment of the present disclosure is configured such that: by using the first conductive member31provided in the seal lip24as a magnetic sensor, the sealing device10inspects the deformation degree of the seal lip24as a change of the interval between the first conductive member and the shaft5based on a change of the inductance. Accordingly, it is possible to inspect the deformation degree of the seal lip24with high accuracy by a simple configuration. Further, even during rotation of the rolling bearing, it is possible to inspect the deformation degree of the seal lip24. Hereby, the deformation degree of the seal lip24can be inspected without reducing operation efficiency of the rolling bearing.

In the first embodiment of the present disclosure, the first conductive member31and the second conductive member32are annular members. However, either one of the conductive members or both conductive members may include a plurality of arcuate members and may be configured such that the arcuate members are arranged at predetermined intervals along the circumference of a circle. Further, in the second embodiment of the present disclosure, the first conductive member31is an annular member, but the first conductive member31may be configured such that several arcuate members are arranged at predetermined intervals along the circumference of a circle.

In the first embodiment of the present disclosure, the first conductive member31functioning as a magnetic sensor and the second conductive member32as a sensing target thereof are prepared as special members for inspecting the change of the inductance, and are placed in the sealing device10. The first conductive member31and the second conductive member32can be hereby placed at respective optimum positions. However, as another example, a member having conductivity and constituting the sealing device10may also be used as at least one conductive member out of the first conductive member31and the second conductive member32.

The member having conductivity and constituting the sealing device10is the core member11, for example. As an example, a sealing device10according to a modification takes the core member11as the second conductive member32, and detects a change of an interval between the first conductive member31and the core member11associated with deformation of the seal lip24, as a change of the inductance of the first conductive member31. In order that the core member11functions as the second conductive member32, a power source is connected to the core member11, so as to apply an alternating voltage thereto. Hereby, a magnetic field is generated around the core member11, so that a change of the interval between the first conductive member31and the core member11can be detected as a change of the inductance of the first conductive member31with high accuracy.

As another example, the core member11is provided as the first conductive member31, so that a change of an interval between the core member11and the second conductive member32associated with deformation of the seal lip24is detected as a change of an inductance of the core member11. In order that the core member11functions as the first conductive member31, the power source60is connected to the core member11so as to apply an alternating voltage thereto, and the measuring device40is connected thereto so as to measure the inductance. Hereby, a magnetic field is generated around the core member11, so that a change of the interval between the core member11and the second conductive member32can be detected as a change of the inductance of the core member11with high accuracy.

Another example of the member having conductivity and constituting the sealing device10is the spring19. As an example, a sealing device10according to another modification takes the spring19as the second conductive member32, and detects a change of an interval between the first conductive member31and the spring19associated with deformation of the seal lip24, as a change of the inductance of the first conductive member31. In order that the spring19functions as the second conductive member32, a power source is connected to the spring19so as to apply a voltage thereto. Since the spring19has a coil shape, a direct voltage is applied thereto. Hereby, a magnetic field is generated around the spring19, so that a change of the interval between the first conductive member31and the spring19can be detected as a change of the inductance of the first conductive member31with high accuracy.

As another example, the spring19is taken as the first conductive member31, so that a change of an interval between the spring19and the second conductive member32associated with deformation of the seal lip24is detected as a change of an inductance of the spring19. In order that the spring19functions as the first conductive member31, the power source60is connected to the spring19so as to apply a voltage to the spring19, and the measuring device40is connected to the spring19so as to measure the inductance. Since the spring19has a coil shape, a direct voltage is applied thereto. Hereby, a magnetic field is generated around the spring19, so that a change of the interval between the spring19and the second conductive member32can be detected as a change of the inductance of the spring19.

Further, as another example, one of the core member11and the spring19may be taken as the first conductive member31and the other one thereof may be taken as the second conductive member32, so that a change of an interval between the core member11and the spring19associated with deformation of the seal lip24may be detected as a change of an inductance of the core member11or the spring19.

When the member having conductivity and constituting the sealing device10is used as at least one conductive member out of the first conductive member31and the second conductive member32, the number of components to be placed in the sealing device10can be restrained. This makes it possible to easily manufacture the sealing device10and to achieve weight reduction of the sealing device10.

Note that, in the above description, the sealing device10is an oil seal, for example. However, the sealing device10may be any sealing device, provided that the sealing device includes a seal lip making close contact with the rotating shaft of the rotational member.

It should be considered that the embodiments described herein are just examples in all respects and are not limitative. The scope of the present disclosure is shown by claims, not by the descriptions, and intended to include all modifications made within the meaning and scope equivalent to the claims.