Rolling bearing unit

A four-row tapered roller bearing is incorporated in the clearance between the inner surface of a housing and the outer surface of a rolling roller. A pair of supporting members supporting sensor devices are fitted in and supported by a part of the inner surface of the housing in such a manner that they are opposed to the ends of outer rings of the four-row tapered roller bearing disposed close to the both axial ends thereof. The sensor devices each comprise a distortion gauge as a detecting portion and a first coil for transmitting as a wireless signal a signal obtained by processing an output signal outputted from the distortion gauge. A second coil for receiving the wireless signal transmitted by the first coil is retained on a part of a member other than the supporting members.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a rolling bearing unit including a rolling bearing and a sensor device, which bears various rolls of rolling mill for iron and steel, paper manufacturing machine, etc. rotatably with respect to a fixed portion and detects the load axially imposed on the rolling bearing (axial load) to judge the deterioration of the machines or adjust the axial load so as to prolong the bearing life.

2. Description of the Related Art

For example, a rolling bearing for roll neck which bears a roller of rolling mill for iron and steel is subject to not only radial load but also axial load during operation. This axial load varies with the degree of deterioration of the rolling mill. Accordingly, the degree of deterioration of the rolling mill can be judged by detecting the axial load. Further, by adjusting the axial load imposed on a member in which an outer ring or inner ring constituting the rolling bearing is fitted to a proper value depending on the axial load thus detected, the fatigue life of the rolling bearing can be prolonged.

FIGS. 12 to 14each show an example of a rolling bearing unit with a sensor device described in JP-B-59-23889 which was invented under these circumstances. A rolling roller1incorporated in a rolling mill has a roll neck2which is born rotatably relative to a fixed housing3by a double-row cylindrical roller bearing4and a pair of tapered roller bearings5,5. The tapered roller bearings5,5are provided on both sides of the double-row cylindrical roller bearing4. The double-row cylindrical roller bearing4can bear the radial load imposed on the rolling roller1. On the contrary, the tapered roller bearings5,5can bear the axial load imposed on the rolling roller1. The double-row cylindrical roller bearing4has an outer ring6aand an inner ring, and the tapered roller bearings5,5have outer ring6b,6band inner rings, respectively. An outer surface of the outer ring6aand an inner surface of a middle portion of the housing3are kept in close contact with each other. A minute clearance is provided between outer surfaces of the outer rings6b,6band an inner surface of both ends of the housing3, respectively.

Supporting members7,7are fitted in and supported by the inner surface of the housing3in the space disposed on both axial ends of the outer rings6b,6b, respectively. Each of the supporting members7,7has an annularly formed main body8and substantially arc protrusions9,9. The protrusions9,9are screwed on an outer surface of the main body8at a plurality of circumferential positions. Each of the protrusions9,9has a convex portion10and a concave portion11. The convex portion10is provided on one axial end of the protrusions9,9(back side as viewed onFIG. 13or upper side as viewed onFIG. 14) and in a middle portion of the protrusion9along the circumference of the main body8. The concave portion11is provided on the other axial end of the protrusions9,9(front side as viewed onFIG. 13or lower side as viewed onFIG. 14) at a position opposite the convex portion10. Each of distortion gauges12,12are attached to an inner side of the concave portion11.

With a forward end of the convex portions10being butted to the end of the small diameter side of the outer rings6b,6b, the protrusions9,9each are disposed interposed between the outer rings6b,6band the part of the housing3. The distortion gauges12,12each are connected to a bridge circuit (not shown) provided there outside with harnesses13,13. The bridge circuit is connected to a distortion meter (not shown).

According to the rolling bearing unit with the sensor device having the constitution described in the JP-B-59-23889, the distortion outputted to a display of the distortion meter and the relationship between distortion and load previously determined can be used to determine the axial load imposed on the tapered roller bearings5,5.

As the related art technical references relating to the present invention, there are also JP-A-2001-35308 and JP-A-2002-5156 which disclose a rolling bearing unit with a sensor device for detecting the load imposed axially on a rolling bearing.

The rolling bearing unit with the sensor device described in the above-mentioned JP-B-59-23889 leaves the following points to be desired:(1) The end of the harnesses13,13connected to the bridge circuit are connected to the distortion gauges12,12provided on the supporting members7,7fitted in and supported by the housing3. In practice, however, the bridge circuit is often disposed at a position remote from the rolling bearing unit with the sensor device. Accordingly, it is necessary that the harnesses13,13be long enough. In this arrangement, the harnesses13,13interfere in the replacement of the tapered roller bearings5,5or double-row cylindrical roller bearing4or the rolling roller1. Thus, the replacement of these parts becomes troublesome. If the supporting members7,7rotate relative to the housing3, it is likely that the harnesses13,13can break.(2) Since the supporting members7,7each have the plurality of protrusions9,9screwed on the main body8, they are troublesome to assemble. In order to enhance the detecting precision of the distortion gauges12,12, it is necessary that the forward end of the convex portions10provided on the protrusions9,9be positioned accurately on the same virtual plane extending perpendicular to the central axis of the supporting members7,7, respectively. However, the main body8and the protrusions9,9are separately formed. Therefore, it is troublesome to secure the dimensional precision and shape precision of the protrusions9,9with respect to the main body8, and then assemble the supporting members7,7in such an arrangement that the forward end of the convex portions10of the protrusions9,9are accurately positioned on the same virtual plane. Accordingly, it is difficult to enhance the detection precision of the distortion gauges12,12while preventing the rise of cost of the rolling bearing unit with the sensor device.

Further, according to the structure disclosed in the above-mentioned JP-A-2001-353508 and JP-A-2002-5156, a supporting member by which the sensor device is supported is not fitted in and supported by a housing in which an outer ring as a fixed ring is fitted in such an arrangement that the supporting member is opposed to an axial end of the outer ring. Further, this sensor device is provided on the inner surface of the housing. In this arrangement, the load imposed axially on the rolling bearing can be difficultly detected to a good precision.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a rolling bearing unit.

A rolling bearing unit of the present invention comprises a rolling bearing and a sensor device as in the related art rolling bearing with the sensor device shown inFIGS. 12 to 14above.

The rolling bearing comprises an inner ring and an outer ring one of which is a rotary ring and the other is a fixed ring, which rotate relative to each other, and a plurality of rolling elements disposed rotatably interposed between an outer ring raceway formed on an inner surface of the outer ring and an inner ring raceway formed on an outer surface of the inner ring. The sensor device detects the load imposed axially on the rolling bearing.

Further, the rolling bearing unit of the present invention comprises a sensor device for detecting the load imposed axially on the rolling bearing, the sensor device having a detecting portion for detecting the load imposed axially on the rolling bearing, and at least a part of a transmitting device for transmitting an output signal outputted from the detecting portion or a signal obtained by processing the output signal as a wireless signal; a supporting member for supporting the sensor device, fitted in and supported by a member in which the outer ring or inner ring as the fixed ring is fitted in such an arrangement that it is opposed to an axial end of the outer ring or inner ring as the fixed ring; and a member having at least a part of a receiving device for receiving the wireless signal transmitted from the transmitting device, the member being separately formed from the supporting member. The detecting portion of the sensor device detects the load imposed axially on the supporting member by the outer ring or inner ring as the fixed ring to detect the load imposed axially on the rolling bearing.

In the above-mentioned rolling bearing of the present invention, the supporting member may comprise an annularly formed main body and protrusions provided axially protruding at a plurality of circumferential positions on both axial ends of the main body in such an arrangement that circumferential phases of the protrusions disposed on the both axial ends of the main body coincide with each other. The main body may have inner annular wall portions and outer annular wall portions, which radially protrude and disposed on the both axial ends of the main body respectively. The main body and protrusions may be integrally formed by working a metallic material. The detecting portion of the sensor device may be disposed on a portion of the periphery of the main body where it coincides with one of the protrusions in the circumferential phase.

Further, in the above-mentioned rolling bearing of the present invention, the sensor device may comprise a modulation/demodulation circuit and a coil as the transmitting device, the modulation/demodulation circuit combining the output signal outputted from the detecting portion with a carrier wave to produce a modulated wave or taking a modulation signal out of the modulated wave received through the coil, the coil transmitting and receiving the modulated wave as the wireless signal.

Moreover, in the above-mentioned rolling bearing of the present invention, the sensor device may comprise a modulation circuit and a coil as the transmitting device, the modulation circuit combining the output signal outputted from the detecting portion with a carrier wave to produce a modulated wave, the coil transmitting the modulated wave as the wireless signal.

Further, in the above-mentioned rolling bearing of the present invention, the sensor device may comprise a modulation circuit and an antenna as the transmitting device, the modulation circuit combining the output signal outputted from the detecting portion with a carrier wave to produce a modulated wave, the antenna transmitting the modulated wave as the wireless signal.

In the above-mentioned rolling bearing of the present invention, the sensor device may comprise an electronic tag having a memory, a control section and a transmission/reception section as the transmitting device, the transmission/reception transmitting and receiving the wireless signal.

According to the rolling bearing unit of the present invention with this constitution, a detected value of load represented by an output signal outputted from the detecting portion of the sensor device or a signal obtained by processing the output signal can be outputted to an output section of an output device provided on a receiving device side. In this arrangement, the operator can easily judge how much the machine provided with this rolling bearing is deteriorated. Further, by adjusting the axial load imposed axially on the member in which the inner ring or outer ring is fitted depending on the detected value of load using an adjustor, the axial load imposed on the rolling bearing can be adjusted to a proper value, making it possible to prolong the life of the rolling bearing. Moreover, the harness or cable for transmitting the signal can be shortened, making it possible to easily replace the member in which the inner ring or outer ring is fitted or the rolling bearing. Further, in the case where the sensor device is provided with the entire transmitting device, it is not necessary to connect the harness or cable to the supporting member by which the sensor device is supported, making the replacement easier. This arrangement also makes it possible to prevent the breaking of the harness or cable.

Further, the supporting member is fitted in and supported by the member in which the outer ring or inner ring as a fixed ring is fitted in such an arrangement that the supporting member is opposed to the axial end of the outer ring or inner ring as the fixed ring. The sensor device, which comprises the detecting portion for detecting the load imposed axially on the supporting member by the outer ring or inner ring as the fixed ring and at least the part of the transmitting device for transmitting the output signal outputted from of the detecting portion or the signal obtained by processing the output signal as a wireless signal, is supported by a part of the supporting member. In this arrangement, the invention can easily detect the load imposed axially on the rolling bearing to a good precision.

Moreover, according to the rolling bearing unit of the present invention, it is not necessary that a plurality of members which are separate bodies be combined to form the supporting member. In this arrangement, the production of the rolling bearing unit with the sensor device can be simplified. Further, a side surface, which is provided on a part of the supporting member for butting to a mating member disposed axially opposed to the supporting member, can be positioned on the same virtual plane extending perpendicular to the central axis of the supporting member without the necessity of troublesome assembly. In this arrangement, the detecting precision of the sensor device can be enhanced while preventing cost rise.

Further, according to the rolling bearing unit of the present invention, the plurality of protrusions for butting to the mating member may be provided at positions where the phase of one of protrusions in the circumferential direction of the supporting member coincides with that of the detecting portion of the sensor device provided on a part of the supporting member. If the sensor device has a plurality of the detecting portions, the circumferential phases of protrusions coincide with those of the detecting portions. In this arrangement, the detecting precision of the sensor device can be enhanced. Moreover, the area of the forward end of the plurality of protrusions, which are subject to load imposed by the mating member, among the parts of the supporting member can be reduced, making it possible to enhance the detecting precision of the sensor device.

Further, according to the rolling bearing unit of the present invention, an external inputting device is provided with a transmitting device for transmitting data to be recorded in the memory constituting the electronic tag as a wireless signal. In this arrangement, data representing information to be managed with regard to the rolling bearing unit with the sensor device such as production step, flow, sale, use, failure and repair can be recorded in the memory without connecting the electronic tag and the external inputting device to the harness or cable. Moreover, the external outputting device such as portable data terminal is provided with a receiving portion for receiving the wireless signal generated by the electronic tag. In this arrangement, date recorded in the memory can be outputted as necessary, making it possible to easily manage the data to be managed. Further, in the case where the rolling bearing unit with the sensor device is no longer required, the data to be managed can be utilized to reuse it easily. Moreover, by arranging the rolling bearing unit with the sensor device such that data representing the material and disassembly step of the rolling bearing unit with the sensor device can be freely recorded in the memory, the disassembly of the rolling bearing unit with the sensor device and the classification of parts thus produced into reusable resources can be automated, facilitating complete recycling that produces no waste parts.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 to 7each show a rolling bearing unit with a sensor device according to a first embodiment of the present invention. In the first embodiment, a rolling bearing unit14with a sensor device is incorporated in a rotary supporting portion on both axial ends of a rolling roller1in a rolling mill for rolling a metallic material such as steel. In some detail, a roll neck2is provided in the central portion on the both axial ends of the rolling roller1, and rotatably supported by a four-row tapered roller bearing15inside a housing3which does not rotate even during use. The rolling bearing unit14comprises the four-row tapered roller bearing15, the pair of sensor devices16,16, a pair of second coils36,36and an external inputting/outputting device17(FIG. 6). The four-row tapered roller bearing15comprises a pair of inner rings18,18, three outer rings19a,19b, conical convex inner ring raceways20,20, conical concave outer ring raceways21,21, and a plurality of tapered rollers22,22. The inner rings18,18are fitted on and fixed to the roll neck2. The three outer rings19a,19bare fitted in and fixed to the housing3. The conical convex inner ring raceways20,20are provided on the outer surface of the inner rings18,18. The conical concave outer ring raceways21,21are provided on the inner surface of the outer rings19a,19b. The plurality of tapered rollers22,22are provided rotatably interposed between the inner ring raceways20,20and the outer ring raceways21,21as rolling elements.

An outer ring spacer23is provided between the adjacent outer rings19aand19band an inner ring spacer45is provided between a pair of adjacent inner rings18and18. A pair of supporting members24,24are each fitted in and supported by the inner surface of the housing3at the positions outside the both axial ends of the three adjacent outer rings19a,19band the two outer ring spacers23,23. These supporting members24each comprise an annularly formed main body26and arc protrusions27,27as shown in detail inFIGS. 4 and 5. The protrusions27,27protrude in the axial direction of the main body26. The protrusions27,27also are provided at a plurality of circumferential positions (8 positions as viewed on the drawing) on the both axial ends of the main body26in such an arrangement that the circumferential phases of the protrusions disposed on the both axial ends of the main body26coincide with each other. Further, the main body26has inner annular wall portions25,25and outer annular wall portions55,55, which radially protrude and disposed on the both axial ends of the main body26respectively. According to the first embodiment of the present invention, the various parts such as protrusions27,27, inner annular wall portions25,25, and outer annular wall portions55,55of the supporting members24,24are integrally formed by subjecting an annular metallic material to work such as cutting. At finishing the surface of the forward end of the protrusions27,27, the plurality of protrusions27,27positioned on the same axial side are preferably worked at the same time.

Further, the sensor devices16,16are each supported by a part of the supporting members24,24. These sensor devices16,16each comprise a plurality of distortion gauges28,28which are detecting portions, a substrate30(as shown inFIG. 5), and a first coil31. The distortion gauges28,28are supported at an axially middle portion on both the inner and outer surfaces of the main body26where they coincide with the protrusions27,27in circumferential phase. The distortion gauges28,28each can detect the axial distortion of the main body26. The substrate30is fixed to one of the both axial ends of the main body26which is opposite to the both ends of the housing3(front side as viewed onFIG. 5). The substrate30is disposed at a position deviated in circumferential phase from the protrusions27,27as shown inFIG. 5. The first coil31is wound round the periphery of the plurality of protrusions27,27outside one (right one as viewed onFIG. 4) of the pair of outer annular wall portions55,55on the side where the substrate30is provided (right side as viewed onFIG. 4or front side as viewed onFIG. 5). Alternatively, the substrate30may be disposed at a position different from the distortion gauges28,28between the inner annular wall portions25,25(or the outer annular wall portions55,55) on the inner surface (or outer surface) of the main body26.

The distortion gauges28,28are combined with each other to form a bridge circuit29as shown inFIG. 7. The bridge circuit29and a load conversion circuit (not shown) connected thereto form a load detection circuit32. The load conversion circuit determines the average value of distortion detected by the distortion gauges28,28on the basis of a voltage signal outputted from the bridge circuit29, and then converts the average value to a signal representing the load (analog signal)

The bridge circuit29shown inFIG. 7is formed by distortion gauges28,28supported by the both inner and outer surfaces of the main body26at eight circumferential positions, totaling16circumferential positions. Among these distortion gauges28,28, a pair of distortion gauges28,28disposed on the inner and outer surfaces at the positions where their phases with regard to the circumferential direction of the main body26are substantial coincidence with each other are connected to each other in series. Further, a pair of distortion gauges28,28disposed radially opposed thereto are connected in parallel. In this arrangement, four sets of circuit elements54,54are provided. These circuit elements54,54form the bridge circuit29. The constitution and operation of other portions of the bridge circuit29are similar to that of known bridge circuits and will not be described in detail.

The substrate30comprises the load conversion circuit portion of the load detection circuit32, an A/D converter33, a memory34, a modulation/demodulation circuit35and a rectifying circuit53(FIG. 6). The A/D converter33converts the analog signal representing the detected value of load from the load detection circuit32to a digital signal. The memory34records the digital signal and data from an external inputting/outputting device17described later. The modulation/demodulation circuit35converts the digital signal read from the memory34to a frequency signal (modulation signal) and then combines the modulation signal and a carrier wave to produce a modulated wave. The modulation/demodulation circuit35also takes a frequency signal (modulation signal) out of the modulated signal sent through the second coil36and first coil31. The first coil31can transmit the modulated signal composed by the modulation/demodulation circuit35to the second coil36described later. The rectifying circuit53converts an alternating voltage induced on the first coil31by the second coil36to a D.C. voltage. The electric power which has thus been converted to D.C. (direct current) is then supplied into the load detection circuit32, the A/D converter33, the memory34and the modulation/demodulation circuit35. In the first embodiment, the first coil31and the modulation/demodulation circuit35form the transmitting device.

The pair of supporting members24,24by which the sensor device16having the aforementioned constitution is supported are fitted in the space on the both axial ends of the combination of the three outer rings19a,19band two spacers23,23on the inner surface of the housing3so that they are supported by the inner surface of the housing3. The housing3has a holding lid37connected and fixed to the axial end thereof (right end as viewed onFIGS. 1 and 2) with a plurality of bolts38. The outer rings19a,19b, the spacers23,23and the supporting members24,24are disposed interposed between an axial inner side (left side as viewed onFIGS. 1 and 2) of the holding lid37and a step39provided on the inner surface of the axial inner end of the housing3. In this arrangement, the forward ends of the protrusions27,27provided on the both axial ends of one of the pair of supporting members24,24disposed axially outside the other (right side as viewed onFIG. 1) are butted to the end of the small diameter side of one of the outer rings19a,19bdisposed outermost (right side as viewed onFIG. 1) and the holding lid37at the position close to the inner diameter portion on the inner surface thereof, respectively. In this arrangement, the forward ends of the protrusions27,27provided on the both axial ends of one of the pair of supporting members24,24disposed axially inside the other (left side as viewed onFIG. 1) are butted to the end of the small diameter side of one of the outer rings19a,19bdisposed innermost (left side as viewed onFIG. 1) and the step39disposed on the axial inner end of the housing3, respectively.

The second coils36,36are disposed on the holding lid37at the position close to the inner diameter portion on the axial inner side thereof and on the step39provided on the axial inner end of the housing3, respectively. Retaining concave grooves40,40are formed over all circumference of the holding lid37at the position close to the inner diameter portion on the axial inner side thereof and the step39, respectively, in the first embodiment. The second coils36,36are accommodated in the retaining concave grooves40,40, respectively. In this arrangement, the second coils36,36and the first coils31,31are disposed concentric with each other and opposed to each other with a minute clearance interposed there between. One end of harnesses41,41passing through the holding lid37or the housing3are connected to the second coils36,36, respectively. To the other end of the harnesses41,41are connected male connectors42,42, respectively.

The external inputting/outputting device17(FIG. 6) is disposed outside the housing3. A pair of cables46,46have female connectors47,47, respectively at one end thereof and are each connected to the external inputting/outputting device17at the other end thereof. The female connectors47,47can connect to the male connectors42,42, respectively. The external inputting/outputting device17comprises an inputting portion48, an outputting portion56, a control section49and an interface50as shown inFIG. 6. The inputting portion48is used for inputting data representing the matter to be managed with regard to the four-row tapered roller bearing15and the sensor devices16,16. The outputting portion56outputs data read from the memory34. The interface50connects the inputting portion48and outputting portion56to the control section49. The control section49comprises a power supply circuit43and a modulation/demodulation circuit44. The power supply circuit43applies an alternating voltage to the second coil36. The modulation/demodulation circuit44has a function of taking a frequency signal (modulation signal) out of the modulated wave sent through the first and second coils31,36and a function of combining the signal representing data sent from the inputting portion48with a carrier wave to produce a modulated wave. In the first embodiment, the second coil36and the modulation/demodulation circuit44form the receiving device.

In the above-mentioned arrangement, firstly, the four-row tapered roller bearing15and the supporting members24,24by which the sensor devices16,16are supported, respectively, are attached in the clearance between the housing3and the roll neck2. Then, the female connectors47,47provided at the end of the cables46,46extending from the external inputting/outputting device17is connected to the male connectors42,42provided at the end of the harness41extending from the axially outer surface of the holding lid37and the axial inner end of the housing3. Data representing the matter to be managed with regard to the four-row tapered roller bearing15such as identification number, operation starting time, mounting position and bearing precision of the four-row tapered roller bearing15, and number of the housing3and rolling roller1is inputted by the inputting portion48provided in the external inputting/outputting device17in the vicinity of the four-row tapered roller bearing15. The data thus inputted is sent through the first and second coils31,36to the sensor devices16,16where it is then recorded in the memory34provided therein. In the memory34is also recorded data representing on which side of the four-row tapered roller bearing15the sensor device16is disposed.

In operation, when the operator outputs the detected value of load on the four-row tapered roller bearing15to the outputting portion56of the external inputting/outputting device17, the instruction such that the data is outputted to the outputting portion56is inputted to the inputting portion48of the external inputting/outputting device17. The signal which has been read from the memory34of the sensor devices16,16on the basis of the input is then transmitted to the external inputting/outputting device17through the first and second coils31,36, respectively, to output the above-mentioned data and the detected value of load to the outputting portion56of the external inputting/outputting device17.

According to the rolling bearing unit with the sensor device of the present invention having the aforementioned constitution, the operator can confirm the detected value of load read from the load detection circuit32of the sensor devices16,16through the memory34at the outputting portion56of the external inputting/outputting device17. Therefore, the operator can easily judge how much the rolling mill is deteriorated. Further, by allowing a rolling mill operation controller57(FIG. 6) to adjust the load imposed axially on the rolling roller1depending on the detected value of load, the load imposed axially on the four-row tapered roller bearing15can be adjusted to a proper value, making it possible to prolong the life of the four-row tapered roller bearing15.

Further, according to the first embodiment, wireless communications are made between the first and second coils31,36to take a signal out of the sensor devices16,16supported by the supporting members24,24and send it to the external inputting/outputting device17. Accordingly, it is not necessary that the harness41or cable46be connected even to the sensor devices16,16. In this arrangement, the total length of these harnesses41or cables46can be reduced. Further, these harnesses41or cables46cannot interfere in the replacement of the rolling roller1or four-row tapered roller bearing15. Thus, the replacement of these parts can be easily conducted.

Moreover, according to the first embodiment, the female connectors47,47provided at the end of the cables46,46extending from the external inputting/outputting device17can be detached from the male connectors42,42provided at the end of the harness41extending from a part of the holding lid37and the inner surface of the housing3, respectively. In this arrangement, even when the cables46,46are long, the female connectors47,47may be merely detached from the male connectors42,42, respectively, to prevent the cables46,46from interfering in the replacement of the rolling roller1or four-row tapered roller bearing15. Thus, the replacement of these parts can be more easily conducted.

Further, since it is not necessary that the harnesses41or cables46be connected even to the sensor devices16,16, the breaking of the harnesses41or cables46can be prevented even when the supporting members24,24by which the sensor devices16,16are supported rotate relative to the housing3.

Further, according to the first embodiment, the supporting members24,24each has various parts such as protrusions27,27etc., integrally formed by working a metallic material. Unlike the related art structure previously mentioned, the supporting members24,24having the aforementioned constitution do not require that a plurality of members as separate bodies be combined with a screw or the like. In this arrangement, the production of the rolling bearing unit14with the sensor device can be simplified.

In order to enhance the detecting precision of the sensor devices16,16, it is necessary that the side faces provided at a part of the supporting members24,24for butting to the mating member disposed axially opposed to the supporting members24,24be substantially positioned on the same virtual plane extending perpendicular to the central axis of the supporting members24,24. According to the first embodiment, the side faces correspond to the forward end of the plurality of protrusions27,27provided on the supporting members24,24. Contrary to the related art structure, the supporting members24,24according to the first embodiment each have various parts integrally formed by working a metallic material. In this arrangement, the forward end of the protrusions27,27provided on the same axial side of the supporting members24,24can be together positioned substantially on the same virtual plane extending perpendicular to the central axis of the supporting members24,24without the necessity of troublesome assembly. In this arrangement, the detecting precision of the sensor devices16,16can be enhanced while preventing cost rise.

Further, according to the first embodiment, the supporting members24,24each comprise an annularly formed main body26and arc protrusions27,27provided axially protruding at a plurality of circumferential positions on the both axial ends of the main body26in such an arrangement that the circumferential phases of the protrusions27,27disposed on the both axial ends of the main body26coincide with each other. The distortion gauges28,28constituting the sensor devices16,16are supported by the axially middle portion where they coincide with the protrusions27,27in circumferential phase on both the inner and outer surfaces of the main body26. In this arrangement, a plurality of protrusions27,27for butting to the mating member disposed axially opposed to the supporting members24,24can be provided at the positions where their phases with regard to the circumferential direction of the main body26are substantial coincidence with those of the distortion gauges28,28. Accordingly, the precision in detection of the load axially imposed on the four-row tapered roller bearing15can be enhanced.

Moreover, according to the first embodiment, the area of the forward end of the plurality of protrusions27,27, which are subject to axial load imposed by the mating member, among the parts of the supporting members24,24can be reduced. In this arrangement, the deformation of the plurality of circumferential positions on the main body26supporting the distortion gauges28,28against the load imposed by the mating member can be raised. Accordingly, the detecting precision of the sensor devices16,16can be made greater than in the case where the both axial ends of the supporting members24,24each are a mere flat area free of protrusions27,27. In the first embodiment, the supporting members24,24have inner annular walls25,25and outer annular walls55,55provided on the both axial ends of the inner and outer surfaces thereof, respectively. In this arrangement, the distortion gauges28,28disposed between the annular walls25,25can be prevented from coming in contact with and being damaged by the inner surface of the housing3or the outer surface of the member disposed opposed to the inner side of the supporting members24,24.

Further, according to the first embodiment, the electric power is supplied into the sensor devices16,16through the first and second coils31,36, making it possible to eliminate the necessity of using a battery as a power supply for operating the various portions of the sensor devices16,16. Accordingly, the necessity of effecting troublesome operation such as removal of the supporting members24,24from the housing3in case of battery consumption can be eliminated, making it possible to reduce operational cost.

Moreover, according to the first embodiment, the sensor devices16,16each comprise the memory34which can record the detected value of load outputted from the load detection circuit32and data representing the matter to be managed with regard to the four-row tapered roller bearing15and the sensor devices16,16. In this arrangement, the matter to be managed with regard to the four-row tapered roller bearing15and the sensor devices16,16, e.g., identification number and operation starting time of the four-row tapered roller bearing15and position of the sensor devices16,16can be easily confirmed. In the first embodiment, in addition to the identification number of the four-row tapered roller bearing15, etc., the load imposed on the supporting members24,24can be outputted to the outputting portion56of the external inputting/outputting device17. Accordingly, even when the rolling mill is provided with a plurality of rolling bearings, the results which have been outputted to the outputting portion56can be easily confirmed relating to the four-row tapered roller bearing15. Moreover, in the first embodiment, the external inputting/outputting device17can be used to record data representing the matter to be managed with regard to the four-row tapered roller bearing15and the sensor devices16,16in the memory34. In this arrangement, the operator can record the aforementioned data in the vicinity of the place where the four-row tapered roller bearing15is incorporated in the machine substantially at the same time with the incorporation. Accordingly, unlike the case where the recording of data is conducted in a place remote from the place of incorporation, the first embodiment can prevent any failure in the recording of data and facilitate the recording of data.

According to the first embodiment, the electric power is supplied into the various portions of the sensor device16through the first and second coils31,36. Accordingly, it is necessary that the harness41connected to the second coil36and the cable46extending from the external inputting/outputting device17be kept connected to each other. However, when a battery is provided inside the sensor devices16, the harness41and the cable46should be connected to each other only when at least one of the data representing the matter to be managed with regard to the detected value of load and the four-row tapered roller bearing15and sensor devices16is outputted.

While the first embodiment comprises protrusions27,27provided on the both axial ends of the supporting members24,24at eight circumferential positions, these protrusions27,27may be provided on the both axial ends of the supporting members24,24at two or more circumferential positions. However, in this case, it is preferred from the standpoint of enhancement of the detecting precision of the sensor devices16,16that these protrusions27,27be provided at circumferentially regular intervals on the supporting members24,24and the distortion gauges28be provided at positions where their circumferential phases coincide with those of these protrusions27,27. Further, in the case where number of the distortion gauges28,28provided on the supporting members24,24is not16, the configuration of the bridge circuit formed by these distortion gauges28,28is designed properly different from that shown inFIG. 7. Moreover, the shape of the section of these protrusions27,27is not limited to arc as in the first embodiment but may be any other shape such as rectangle and circle. In any case, however, it is preferred from the standpoint of enhancement of the detecting precision of the sensor devices16,16that the shape and sectional area of the protrusions27,27be the same from one protrusion to another.

The four-row tapered roller bearing15may have a sealing structure (not shown) provided on the both ends thereof to hermetically seal the interior of the four-row tapered roller bearing15. Alternatively, the four-row tapered roller bearing15may have the pair of outer rings19a,19aamong the outer rings19a,19bconstituting the four-row tapered roller bearing15, which are provided close to the both ends thereof, may have a seal ring fixed to the end of the inner diameter portion. In the case where such a sealing structure or seal ring is provided, even when the holding lid37is removed from the housing3, the interior of the four-row tapered roller bearing15can be hermetically sealed to prevent the leakage of the grease from the interior of the four-row tapered roller bearing15. Further, a temperature sensor (not shown) for detecting the temperature of the four-row tapered roller bearing15may be provided. In the case where such a temperature sensor is provided, the temperature data detected by the temperature sensor and the distortion data detected by the sensor devices16,16can be used to allow the load detection circuit32(FIGS. 6 and 7) to determine the load imposed on the four-row tapered roller bearing15with a higher precision (such that the measurements of load can be corrected by temperature data). The temperature sensor may be provided on the supporting members24,24. Further, it can be arranged such that data representing the detected value from the temperature sensor can be recorded in the memory34of the sensor devices16,16and can be outputted from the external inputting/outputting device17.

As shown inFIG. 8, the supporting member24may have an inner cover58and an outer cover59provided on the inner surface and the outer surface thereof, respectively. The inner cover58is a cylinder formed by a synthetic resin, soft steel or the like and has outward collars60,60formed on the outer surface of the both axial ends thereof, respectively. The inner cover58is fitted in the inner wall portions25,25provided on the inner surface of the supporting member24. Further, the inner wall portions25,25are engaged with the outward collars60,60, respectively. In this arrangement, the inner cover58is supported by the supporting member24. The outer cover59, is a cylinder formed by a synthetic resin, soft steel or the like and has inward collars61,61formed on the inner surface of the both axial ends thereof, respectively. The outer cover59is fitted on the outer annular wall portions55,55provided on the outer surface of the supporting member24. Further, the inward collars61,61are engaged with the outer annular walls55,55, respectively. In this arrangement, the outer cover59is supported by the supporting member24. In the case where the supporting member24has the inner and outer covers58and59provided thereon, the damage of the plurality of distortion gauges28,28supported by the supporting member24can be more effectively prevented.

FIG. 9illustrates a second embodiment of the present invention. Unlike the first embodiment, the present embodiment has no A/D converter33, modulation/demodulation circuit35, memory34and inputting portion48(seeFIG. 6) provided in the sensor device16and the external inputting/outputting device17. Instead, the second embodiment comprises a modulation circuit51provided in the sensor devices16as well as a demodulation circuit52provided in the external inputting/outputting device17. The modulation circuit51converts the signal representing load outputted from the load detection circuit32provided in the sensor devices16to a modulation signal and combine it with a carrier wave to produce a modulated wave. The demodulation circuit52takes the modulation signal out of the modulated wave transmitted to the external inputting/outputting device17through the first coil31provided on the sensor device16and the second coil36provided on the external inputting/outputting device17.

Unlike the first embodiment, the second embodiment does not allow the first coil31to receive a wireless signal. Further, the second coil36does not transmit a wireless signal. In the second embodiment, the modulation circuit51and the first coil31form the transmitting device and the demodulation circuit52and the second coil36form the receiving device.

Unlike the first embodiment, the rolling bearing unit with the sensor device according to the second embodiment has no memory34provided in the sensor devices16. In this arrangement, the rolling bearing unit with the sensor device can neither record data representing the matter to be managed with regard to the four-row tapered roller bearing15and the sensor devices16in the memory34nor output data recorded in the memory34to the outputting portion56. However, in the second embodiment, the number of parts can be less than in the first embodiment, making it possible to reduce the cost easily.

The other structures and operation of the second embodiment are similar to that of the first embodiment and will not be described below.

FIG. 10illustrates a third embodiment of the present invention. In the third embodiment, a double-row tapered roller bearing62is provided to bear the axial ends of the rolling roller1rotatably relative to the housing3. The double-row tapered roller bearing62comprises a pair of outer rings63,63, an outer ring spacer23, an inner ring15and a plurality of tapered rollers22,22which each are rolling elements. The pair of outer rings63,63and the outer ring spacer23are fitted in and fixed to the axial end of the housing3. The inner ring15is fitted on and fixed to the axial end of the rolling roller1. The plurality of tapered rollers22,22are disposed interposed between conical convex inner ring raceways20,20provided on the outer surface of the inner ring15and conical concave outer ring raceways21,21provided on the inner surface of the outer rings63,63, respectively. A pair of supporting members24,24are fitted in the space disposed on the both axial ends of the pair of outer rings63,63and the outer ring spacer23disposed in combination on the inner surface of the housing3so that they are supported by the housing3. Among the parts of the supporting members24,24, the supporting member24disposed outside the other (right side as viewed onFIG. 10) is disposed interposed between the inner side of the holding lid37fixed to the outer end of the housing3and the end of one of the pair of outer rings63,63disposed outside the other. Among the supporting members24,24, the supporting member24disposed inside the other (left side as viewed onFIG. 10) is disposed interposed between a step68provided on the inner surface of the end of the housing3and the end of one of the pair of outer rings63,63disposed inside the other.

In particular, unlike the second embodiment shown inFIG. 9, the third embodiment has no first coil31, rectifying circuit35and load detection circuit32(seeFIG. 9) provided in the sensor devices16,16provided in the supporting members24,24. Instead, the third embodiment comprises a distortion detection circuit (not shown) for determining the average value from the detected value of distortion of the supporting members24,24from a plurality of distortion gauges and an electric power (not shown). The end of harnesses64,64extending through the interior of the housing3and connected to a modulation circuit51(seeFIG. 9) provided in the sensor devices16,16each are connected to a first antenna65fixed to the outer surface of the housing3. A wireless signal representing distortion detected by the distortion detection circuit can be transmitted from the first antenna65. In the third embodiment, the first antenna65and the modulation circuit51provided in the sensor devices16,16form the transmitting device.

Disposed outside the housing3are a receiving device66and a rolling mill operation controller57. The receiving device66comprises a second antenna67, a demodulation circuit52(seeFIG. 9) and an interface portion50(seeFIG. 9). The second antenna67receives a wireless signal representing the detected value (average value) of distortion transmitted by the first antenna65. The demodulation circuit52and the rolling mill operation controller57are connected to each other with the interface portion50. The rolling mill operation controller57converts the detected value of distortion represented by the signal transmitted by the sensor devices16,16via the first and second antennas65,67to the load imposed axially on the double-row tapered roller bearing62always since the moment when the power supply is switched ON. Further, the rolling mill operation controller57adjusts the load imposed axially on the rolling roller1depending on the load thus determined.

In the third embodiment having the aforementioned constitution, the end of the harnesses64,64connected to the sensor devices16,16supported by the supporting members24,24and extending through the interior of the housing3are connected to the first antenna65fixed to the exterior of the housing3. In this arrangement, the replacement of the tapered roller62or rolling roller1becomes more troublesome than in the aforementioned embodiments. If the supporting members24,24are rotated relative to the housing3, the possibility such that the harnesses64,64do not break is less than the aforementioned embodiments. In the third embodiment, however, wireless communications are conducted between the first and second antennas65,67to take a signal representing distortion out of the sensor devices16,16and transmit it to the receiving device66. In this arrangement, it is not necessary that the sensor devices16,16supported by the supporting members24,24and the receiving device66be connected to each other with a long harness. Accordingly, the replacement of these parts can be more easily conducted than in the related art structure having the sensor devices16,16connected to external devices with a long harness.

The other structures and operation of the third embodiment are similar to that of the second embodiment shown inFIG. 9and will not be described below.

In the aforementioned embodiments, the four-row tapered roller bearing15or double-row tapered roller bearing62may be replaced by other types of rolling bearing such as cylindrical roller bearing, ball bearing and combination of cylindrical roller bearing and tapered roller bearing. While the embodiments have been described with reference to the case where a pair of supporting members24,24supporting the sensor device16are provided on the both ends of the four-row tapered roller bearing15, respectively, one supporting member24supporting the sensor device16may be disposed interposed between the fixed rings constituting the pair of rolling bearings. In this case, considerations such as provision of an additional sensor are needed to confirm in which direction load is imposed on the pair of rolling bearings. However, even when no such an additional sensor is provided, the magnitude of the load can be detected.

In the aforementioned embodiments, the supporting member24fitted in and supported by the housing3in which the outer rings19a,19band63as fixed rings are fitted may have an electronic tag (non-contact type IC device) provided with a memory, a control section and a transmission/reception section for transmitting and receiving a wireless signal, which is fixed to a part thereof. For example,FIG. 11illustrates a fourth embodiment of the present invention. In the fourth embodiment, an electronic tag69is embedded in and fixed to an axial end (front side as viewed onFIG. 11) of the main body26constituting the supporting members24at a position where its circumferential phase deviates from that of the protrusions27,27and the substrate30in the structure of the first embodiment shown inFIGS. 1 to 8. The electronic tag69is a chip-shaped non-contact IC device provided with a memory, a control section and a transmission/reception section for transmitting and receiving a wireless signal. This memory can record data representing information to be managed with regard to the rolling bearing unit with a sensor device such as production step, flow, sale, use, failure, repair, material and disassembly step. The transmission/reception section has a function of converting the digital signal read from the memory to a frequency signal (modulation signal), then combining the modulation signal and a carrier wave to produce a modulated wave and then generating it as a wireless signal and a function of receiving a wireless signal transmitted by an external inputting/outputting device (not shown) such as portable data terminal, taking the frequency signal (modulation signal) out of the modulated wave of the wireless signal and then converting it to a digital signal. When a wireless signal is transmitted from the external inputting/outputting device to the transmission/reception section, the control section acts to record data represented by the wireless signal in the memory or read data from the memory and allow the transmission/reception section to transmit the wireless signal. In the fourth embodiment, a battery for operating the parts of the electronic tag69is provided in the supporting members24. However, by arranging such that the electronic tag69can be energized by a wireless wave from the external inputting/outputting device, the electronic tag69can be used free of battery.

In the fourth embodiment having the aforementioned constitution, data representing information to be managed with regard to the rolling bearing unit with the sensor device such as production step, currency (flow), sale, use, failure and repair can be recorded in the memory constituting the electronic tag69without connecting the electronic tag69and the external inputting device to each other with a harness or cable. Further, the data recorded in the memory can be outputted from the external inputting/outputting device as necessary, facilitating the management of data to be managed such as production step. Moreover, when the rolling bearing with the sensor device is no longer needed, the data to be managed can be utilized to reuse it easily. Moreover, in the fourth embodiment, the memory can record data representing the material and disassembly step of the rolling bearing unit with the sensor device, making it easy to automate the disassembly of the rolling bearing unit with the sensor device and the classification of parts thus produced into reusable resources and hence facilitating complete recycling that produces no waste parts.

Though not shown, the present invention may be arranged such that data representing the value of load imposed axially on the rolling bearing detected by the detecting portion of the sensor device can be recorded in the memory constituting the electronic tag69and a signal representing the data read from the memory can be transmitted as a wireless signal from the transmission/reception section of the electronic tag69, which is a transmitting device. In this case, the detected value is outputted to the outputting portion of the external outputting device such as portable data terminal and the load imposed axially on the rolling bearing is adjusted with this detected value. In this arrangement, it is not necessary that the external inputting/outputting device and the member supporting the rolling bearing such as housing3be connected to each other with a harness or cable. Accordingly, the replacement of parts to be provided on rotary bearing such as the rolling bearing can be more easily facilitated and the breaking of the harness or cable can be prevented.

The present invention can be effected also when the fixed ring is the inner ring. In this case, the supporting member by which the sensor device is supported is fitted in and fixed to the member in which the inner ring is fitted.

The rolling bearing unit with a sensor device of the present invention has the aforementioned constitution and operation, making it possible to facilitate the replacement of parts to be provided on the rotary bearing portion and prevent the breaking of the cable or harness.