Abstract:
A rolling bearing device includes a rolling bearing and an oil supply unit. The oil supply unit includes a lubrication oil tank, a pump which sucks lubrication oil from the lubrication oil tank and discharges the lubrication oil from a discharge porta driving section which drives the pump and a generator section which supplies the driving section with electric energy. The oil supply unit is attached to a fixed-ring-side member of the rolling bearing or a spacer adjacent to the rolling bearing. The oil supply unit further includes a communication unit which transmits operation information of the oil supply unit to an outside.

Description:
TECHNICAL FIELD 
     The present invention relates to rolling bearing devices used in machine tools, industrial machinery, etc., and particularly to a rolling bearing device constituted as a combination of a rolling bearing and an oil supply unit. 
     BACKGROUND ART 
     A rolling bearing device which incorporates an oil supply unit therein is conventional (see Patent Literature 1). In this rolling bearing device, an oil supply unit is mounted on an inner diameter surface of one of two mutually opposed track rings of the rolling bearing, or a fixed-side track ring in this case. The oil supply unit includes a lubrication oil tank which stores lubrication oil; a pump which pumps out the lubrication oil stored in the lubrication oil tank into the bearing; and an electric power generator which drives the pump. The device also includes means which controls the pump in accordance with bearing conditions thereby controlling an amount of discharged oil. 
     Patent Literature 2 also discloses a rolling bearing device which includes a similar oil supply unit. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: JP-A 2004-108388 Gazette 
     Patent Literature 2: JP-A 2004-316707 Gazette 
     SUMMARY OF INVENTION 
     Technical Problem 
     Often, the oil supply unit which is incorporated near the bearing is in an environment which is inaccessible from outside. In order to monitor, troubleshoot or otherwise service the oil supply unit, it is necessary to perform regular overhaul or provide communication lines, for example, extended to the outside. This poses limits on use and/or assemblability. 
     It is therefore an object of the present invention to provide a rolling bearing device which allows checking if its oil supply unit is functioning properly while the bearing device is under an assembled state, without any need for disassembly or communication lines, for example, extended to the outside. 
     Solution to Problem 
     As a solution to the above-described problems, the present invention provides a rolling bearing device comprising a combination of a rolling bearing and an oil supply unit which includes at least: a lubrication oil tank, a pump which sucks lubrication oil from the lubrication oil tank and discharges the lubrication oil from a discharge port; a driving section which drives the pump; and a generator section which supplies the driving section with electric energy. The oil supply unit is attached to a fixed-ring-side member of the rolling bearing or a spacer adjacent to the rolling bearing, and the oil supply unit further includes, within itself, a communication unit which transmits operation information of the oil supply unit to an outside. 
     The oil supply unit may have its constituent members incorporated inside a housing to form a unit for attaching to/detaching from the housing. 
     The communication unit may be provided by one which transmits the information by means of an oscillatory wave. 
     There may be a plurality of the oil supply units, each served by the communication unit so that these oil supply units are simultaneously usable. 
     The rolling bearing device according to the present invention can be usable in machine tools, wind turbines and railway systems. 
     Advantageous Effects of Invention 
     According to the present invention, a communication unit which transmits operation information of the oil supply unit to an outside is provided inside the oil supply unit. Therefore, it is possible to check the oil supply unit as assembled, that it is functioning properly. Further, detection by means of oscillatory waves provides such advantages as it enables wireless information communication possible, it makes it possible to improve assemblability, and it enables simultaneous use of a plurality of the oil supply units. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a sectional view taken in lines A-A in  FIG. 3 . 
         FIG. 2  is a partial sectional view taken in lines B-B in  FIG. 3 . 
         FIG. 3  is a sectional view of an oil supply unit taken in lines X 1 -X 1  in  FIG. 1 . 
         FIG. 4  is an enlarged sectional view showing an example of an electric power source of an oil supply unit. 
         FIG. 5  is an enlarged sectional view showing an example of an electric power source of an oil supply unit. 
         FIG. 6  is an enlarged sectional view showing an example of an electric power source of an oil supply unit. 
         FIG. 7  is an enlarged sectional view showing an example of an electric power source of an oil supply unit. 
         FIG. 8  is a detailed block diagram of a controller. 
         FIGS. 9A and 9B  are schematic illustrations which show an example of a communication device that utilizes oscillatory waves in information transmission.  FIG. 9A  shows a state before oscillation, whereas  FIG. 9B  shows a state after oscillation. 
         FIG. 10  is a schematic illustration which shows an example including a communication devices that utilize oscillatory waves in information transmission. 
         FIG. 11  is a schematic illustration which shows an example including a plurality of communication devices that utilize oscillatory waves in information transmission. 
         FIG. 12  is a schematic illustration which shows an example where an oil supply unit according to the present invention is mounted around a main shaft of a machine tool. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments of the present invention will be described based on the attached drawings. 
     The rolling bearing device  10  according to the embodiments shown in  FIG. 1  through  FIG. 3  includes a rolling bearing  11 ; a spacer  12  press-contacted onto an axial end of the rolling bearing; and an oil supply unit  13  incorporated in the spacer  12 ; and when used, is assembled into a space between a rotation shaft  14  and a housing  15 . The rolling bearing  11  has another end, on which another spacer  16  is press-contacted. These two spacers  12 ,  16  provide axial positioning of the rolling bearing  11 . The rotation shaft  14  in this embodiment is horizontal. 
     The rolling bearing  11  may be provided by whichever of an angular contact ball bearing and a deep groove roller bearing, and includes a rotation-side track ring provided by an inner ring  17 ; an outer ring  18  on a fixed side; a predetermined number of rolling elements  19  placed between these track rings; and a retainer  21  which keeps a predetermined distance between the rolling elements  19 . The rolling bearing  11  is pre-packed with desirable grease, and a seal plate  22  is attached to an end on the spacer  16  side. 
     The spacer  12  includes an inner-ring-side spacer  12   a  and an outer-ring-side spacer  12   b . The inner-ring-side spacer  12   a  is fitted in and fixed to the rotation shaft  14  side and is press-contacted onto an end surface of the inner ring  17 . The outer-ring-side spacer  12   b  is fitted in and fixed to an inner diameter surface of the housing  15 , and is press-contacted onto an end surface of the outer ring  18 . The other spacer  16  is also fitted in and fixed to the rotation shaft  14  side and the housing  15  side in the same fashion, and is press-contacted onto the other end surfaces of the inner ring  17  and of the outer ring  18 . 
     As shown in  FIG. 3 , the oil supply unit  13  includes a generator section  41 , a charger section  42 , a controller  43 , a driving section  44 , a pump  45 , a lubrication oil tank  46 , a communication unit  49  which wirelessly transmits operating information of the oil supply unit  13 , and other components, which are arranged in an annular housing  24  in a circumferential direction thereof. 
     As shown in  FIG. 2 , the annular housing  24  of the oil supply unit  13  is constituted by a housing main body  24   a  which has a generally U-shaped section with an open end facing away from the rolling bearing  11 ; and a lid  24   b  which closes the open end of the housing main body  24   a  and is detachable from/attachable to the housing main body  24   a . The housing main body  24   a  and the lid  24   b  are made of the same thermally plastic resin material such as PPS. 
     The lid  24   b  of the housing  24  is fixed to the housing main body  24   a  with screws  24   c . By unscrewing the screws  24   c  and removing the lid  24   b , it becomes possible to replenish the lubrication oil tank  46  inside the housing main body  24   a  with lubrication oil without removing the entire oil supply unit  13 . 
     The housing main body  24   a  has its outer circumferential surface adhesively fixed to an inner diameter surface of the outer-ring-side spacer  12   b . The adhesive for fixing the housing main body  24   a  may be provided by epoxy resin for example. 
     Next, the lubrication oil tank  46  which is incorporated inside the housing main body  24   a  is provided by a bag  46   a  of an elastic resin, and is disposed in an arcuate form along the annular casing  24 . 
     The bag  46   a  has a suction tube  45   a  connected to the pump  45 . The suction tube  45   a  may be integrated with the bag  46   a  by sandwiching the tube between two films of resin which will be formed into the bag  46   a  and then performing thermal welding to complete the bag  46   a.    
     When the bag  46   a  is formed by blow molding, a suction tube  45   a  may be blow-formed integrally with the bag  46   a.    
     The bag  46   a  which constitutes the lubrication oil tank  46  can be formed of such a material as nylon, polyethylene, polyester and polypropylene; there is no specific limitation to the material as far as the material is not attacked by lubrication oil stored in the bag  46   a.    
     Lubrication oil which is loaded in the bag  46   a  of the lubrication oil tank  46  desirably has a viscosity of VG22 for example, since an excessively high viscosity will cause too much burden on the pump and the power source. 
     The pump  45  has a suction tube  45   a  which sucks lubrication oil from the lubrication oil tank  46 ; and a discharge tube  45   b  from which the sucked lubrication oil is discharged. The discharge tube  45   b  has a discharge nozzle  45   c  at its tip, from which lubrication oil is supplied to between the fixed-side track ring and the rotation-side track ring of the rolling bearing  11 . 
     As the pump  45  is driven, lubrication oil in the lubrication oil tank  46  is sucked. The lubrication oil is supplied from the discharge nozzle  45   c  at a tip of the discharge tube  45   b  to between a fixed and a rotating track rings of the rolling bearing  11 . After a predetermined amount of the lubrication oil is supplied, the pump  45  is stopped. 
     Even if the pump  45  is stopped, interior of the pump  45  and interior of the tube are filled with lubrication oil, so there can be a case where lubrication oil inside the lubrication oil tank  46  is siphoned and leaked out of the discharge nozzle  45   c . In order to prevent this leakage, a leak prevention mechanism which prevents lubrication oil leakage is provided in discharge tubing of the pump  45 . 
     This leak prevention mechanism can be implemented as shown in  FIG. 3  as an arrangement that the discharge tube  45   b  is provided with an on-off valve  48 , and the on-off valve  48  opens only when the pump  45  is working whereas the on-off valve  48  is closed in all the other occasions. Another example is an arrangement that after the pump  45  is driven and the oil supply operation is finished, the pump  45  is driven in reverse direction to introduce air into the discharge tubing. 
     Timing of the supply of lubrication oil, i.e., timing to drive the pump  45  may be when electricity is charged in a condenser in the charger section  42  and a predetermined voltage is reached. If power generation efficiency is too good and the charging time is too short, the stored voltage may be discharged to a resister, for example, when a predetermined voltage value is reached, so that an interval may be made in operation timing of the pump  45 . In this case, there is a cycle(s) of charging and discharging before the pump  45  is operated. The number of this charge-discharge cycles can be used in controlling the operation interval of the pump  45 . As another example, a timer function may be used to trigger when the power storage voltage is reached a predetermined value, to provide an interval in the operation cycle of the pump  45 . In this case, the above-described charge-discharge cycle is not repeated. 
     The suction tube  45   a , which is connected to the suction side of the pump  45 , extends into the lubrication oil tank  46  to suck lubrication oil stored in the lubrication oil tank  46 . 
     On the other hand, the discharge tube  45   b  which is connected to the discharge side has its tip connected to a discharge nozzle  45   c  for discharging lubrication oil into the rolling bearing. It is desirable that the discharge nozzle  45   c  has its tip disposed at a location between the inner and the outer rings of the bearing closely to the inner ring&#39;s outer circumferential surface. The discharge nozzle  45   c  has a nozzle hole of an appropriate inner diameter based on a relationship between surface tension due to base oil viscosity and the amount of discharge. 
     The annular housing  24  incorporates, other than the lubrication oil tank  46 , the following and other components in its circumferential direction; the generator section  41 , the charger section  42 , the controller  43 , the driving section  44 , the pump  45 , and the communication unit  49  which wirelessly transmits operating information of the oil supply unit  13 . 
     As shown in  FIG. 4 , the generator section  41  can be provided by one which generates electric power by way of Seebeck effect. When the rolling bearing device  10  is operating, temperature of the inner ring  17  and the outer ring  18  increases due to friction heat with the rolling elements  19  (see  FIG. 1 ). In general configuration, the outer ring  18  is assembled into the housing  15  of the machine it serves, and therefore loses heat by thermal conduction, resulting in temperature difference between the inner ring  17  and the outer ring  18 . Different temperatures conducted to the respective heat conductors  52 ,  53  causes the Seebeck element  54  to have temperature difference between its two end surfaces, causing the element to generate electric power according to Seebeck effect. 
     When using the above configuration where heat conductors  52 ,  53  are provided to penetrate the inner circumferential surface and the outer circumferential surface of the housing main body  24   a  respectively and a Seebeck element  54  is placed between these heat conductors  52 ,  53 , an adhesive having good heat conductivity should desirably be used on a surface where the heat conductor  52  which penetrates the outer circumferential surface of the housing main body  24   a  makes contact with the inner diameter surface of the outer ring-side spacer  12   b . It should be noted here that the heat conductor  52  which is on the outer ring-side has its outer diameter equal to an inner diameter of the outer ring spacer  12   b  and is fitted thereto for improved heat release. On the other hand, the heat conductor  53  which is on the inner ring side has its inner diameter surface not in contact with the inner ring spacer  12   a . If possible, it is desirable that the outer ring-side and the inner ring-side heat conductors  52 ,  53  have the same volume. 
     Preferably, thermal grease, for example, should be applied between the inner diameter surface of the outer-ring-side spacer  12   b  and the heat conductor  52 ; between the heat conductor  52  and the Seebeck element  54 ; and between the Seebeck element  54  and the inner-ring-side heat conductor  53 , for improved contact and heat conductivity. Thermal grease generally contains silicone as a primary ingredient. The heat conductors  52 ,  53  should be made of a metal which has a high heat conductivity rate. For example, silver, copper, gold, etc. are good candidates, among which copper is the most common due to cost reasons. In addition, copper alloys which contain copper as a primary ingredient can also be used. Further, sintered bodies containing copper as a primary ingredient are also usable. 
     Other than those which generate electric power by way of Seebeck effect, the generator section  41  may be provided by any of those shown in  FIG. 5 ,  FIG. 6  and  FIG. 7 . 
     The one shown in  FIG. 5  is applicable when there is an alternating magnetic field inside the rolling bearing device  10 . Inside built-in spindles of machine tools, or near high-frequency apparatus which handle large amount of electric power, there is leakage magnetic flux or high-frequency radiation. The leakage flux is utilized to generate power by way of electromagnetic induction. More specifically, a combination of an iron core  55  which has an E-shaped profile with one of its sides open, and a coil  56  are combined to catch the alternating magnetic field efficiently to generate power by electromagnetic induction. The open end of the iron core  55  is provided with an insulating base  57 . If the frequency of the leak flux is known, the iron core  55  may be eliminated and the coil  56  which resonates with the frequency of the leak flux may be used. 
     The one shown in  FIG. 6  is applied when there is vibration inside the rolling bearing device  10 . Specifically, a fixed-side insulation substrate  58  is opposed by a moving-side insulation substrate  59 , with each of the substrates being formed with a large number of electrodes  60  and only the electrodes  60  on the fixed-side insulation substrate  58  being laminated with electrets  61  to oppose to the electrodes  60  on the moving-side insulation substrate  59 , with a gap. The moving-side insulation substrate  59  is only movable in a direction indicated by Arrow a in the drawing by a mover  62 . 
     When there is vibration in the rolling bearing device  10 , the mover  62  causes the moving-side insulation substrate  59  to oscillate in the Arrow a direction. This generates electric charge between the electrodes  60  due to electrostatic induction caused by relative movement between the fixed-side insulation substrate  58  and the moving-side insulation substrate  59 , and by the electrets  61  thereon. The generated charge is tapped for use as electric power. 
     The one shown in  FIG. 7  is also for application when there is vibration inside the rolling bearing device  10 . Specifically, an elastic sheet of piezoelectric body  64  is disposed between a fixed-side insulation substrate  58  and a weight  63 . Vibration generated in the rolling bearing device  10  causes the weight  63  to oscillate in the Arrow a direction due to the weight  63  and the piezoelectric body  64 . The process causes deflection in the piezoelectric body  64 , and an electromotive force by way of induced polarization. The generated electromotive force is tapped for use as electric power. 
     Electric charge generated by the generator section  41  is stored in the charging section  42  which is provided by a battery, condenser, etc. If a condenser is employed, an electric double layer condenser (capacitor) is desirably used. 
     As shown in  FIG. 8 , the controller  43  has sensors such as a bearing temperature sensor  47   a , a bearing rotation sensor  47   b , a lubricant remaining quantity sensor  47   c , and a lubrication oil temperature sensor  47   d . Signals from these sensors are inputted to a CPU  51 , which then automatically controls the pump  45  in accordance with temperature and rotation status of the rolling bearing  11 , thereby controlling the amount of lubrication oil supply. 
     The communication unit  49  is attached to the outer-ring-side spacer  12   b  as shown in  FIG. 1 . The communication can be made by means of oscillatory waves. Use of oscillatory waves makes wireless communication possible and improves assemblability. 
       FIG. 9  shows an oscillatory wave generator  70 . Referring to  FIGS. 9A and 9B , a piezoelectric body  71   b  is pasted onto a metal plate  71   a . On a surface of the metal plate  71   a  facing away from the piezoelectric body  71   b , a hammer  72  is provided. These are supported by a fixed case  73 , which is fixed to an oscillatory wave conduction medium  74 . The hammer  72  and the oscillatory wave conduction medium  74  are separated from each other by a small gap  75 . As a voltage is applied to the piezoelectric body  71   b  in this component, a piezoelectric effect (inverse piezoelectric effect) causes the piezoelectric body  71   b  to deform mechanically as shown in  FIG. 9B . Accordingly, the metal plate  71   a  is deformed, causing the hammer  72  to hit the oscillatory wave conduction medium  74  to become a source of oscillatory wave, to generate oscillatory waves inside the oscillatory wave conduction medium  74 . The oscillatory waves travel through the oscillatory wave conduction medium  74 . It should be noted here that in an actual application, the oscillatory wave conduction medium  74  is provided by the housing  24  or the like which houses the outer-ring-side spacer  12   b  and the oil supply unit  13  in  FIG. 1 . 
     By using the oscillatory waves obtained by the above-described methods, communication is performed as follows: 
     As shown in  FIG. 10 , the oscillatory waves are detected by an oscillatory wave detector  77  which is disposed to oppose to the oscillatory wave generator  70  to sandwich the oscillatory wave conduction medium  74 . 
     In  FIG. 10 , the oscillatory wave generator  70  is driven at a frequency generated by a wave-form generator  76  which generates an oscillatory wave A of a predetermined frequency. This oscillatory wave A travels through the oscillatory wave conduction medium  74  and reaches the oscillatory wave detector  77 . The oscillatory wave detector  77  converts the oscillatory wave A into an electrical signal. A reference symbol B indicates a detected wave form. 
     By utilizing the communication means described above, it is possible to wirelessly check a state of operation of the oil supply unit  13  which is assembled inside the relevant component. In  FIG. 10 , a reference symbol  76  indicates the wave-form generator for generation of the oscillatory waves A, a reference symbol  78  indicates an amplifier, a reference symbol  74  indicates the oscillatory wave conduction medium, and a reference symbol  77  indicates the detector. 
     The state of operation of the oil supply unit  13  can be specifically identified by the following means: The oscillatory wave A is generated at each time of pump operation. Each time the oscillatory wave A is detected, it is counted in an accumulating fashion. This makes it possible to estimate how much lubricant remains. At the same time, it is also possible to confirm that the oil supply unit  13  is functioning properly. 
     A plurality of oil supply units  13  may be assembled to implement the communication means, as shown in  FIG. 11 . 
     Basic constituent elements are identical with those shown in  FIG. 10 ; however, each of the two components has one of two oscillators  76   a ,  76   b  which are different from each other in the frequencies they generate. Also, a filter  79  is provided on the detection side, to receive signals of specific frequencies. Utilizing this means makes it possible to check a state of operation of a specific oil supply unit. 
       FIG. 12  shows rolling bearing devices  10  each incorporating an oil supply unit  13  that has the functions described above.  FIG. 12  shows part of a spindle (rotation shaft  14 ) around which the oil supply units  13  are mounted. The oscillatory wave A travels through the outer-ring-side spacer  12   b  and the housing  15 . Then, the oscillatory wave A is detected by an oscillatory wave detector  77  which is attached to the housing  15 . The frequency of the oscillatory wave A is selected to be different from the vibration frequency generated by the rolling bearing  11  and from a natural frequency (resonant frequency) of the spindle  14 . By selecting such a frequency, it becomes easy to detect the oscillation generated by the oscillatory wave generator and to eliminate unnecessary resonance of the components. 
     As described above, by providing an oscillatory wave communication component inside the oil supply unit  13 , it becomes possible to check an electrical component as assembled, that the electrical component is functioning properly. Further, detection by means of oscillatory waves provides such advantages as it enables wireless information communication possible, it makes it possible to improve assemblability, and it enables simultaneous use of a plurality of the oil supply units  13 . 
     REFERENCE SIGNS LIST 
     
         
           10  Bearing Device 
           11  Rolling Bearing 
           12  Spacer 
           12   a  Inner Ring Side Spacer 
           12   b  Outer-Ring-Side Spacer 
           13  Oil Supply Unit 
           14  Rotation Shaft 
           15  Housing 
           16  Spacer 
           17  Inner Ring 
           18  Outer Ring 
           19  Rolling Element 
           21  Retainer 
           22  Seal Plate 
           24  Housing 
           24   a  Housing Main Body 
           24   b  Lid 
           24   c  Screw 
           41  Generator Section 
           42  Charger Section 
           43  Controller 
           44  Driving Section 
           45  Pump 
           45   a  Suction Tube 
           45   b  Discharge Tube 
           45   c  Discharge Nozzle 
           46  Lubrication Oil Tank 
           46   a  Bag 
           46   b  Thermally Welded Portion 
           47   a  through  47   d  Sensors 
           48  ON-OFF Valve 
           49  Communication Unit 
           51  CPU 
           52 ,  53  Conductors 
           54  Seebeck element 
           55  Iron Core 
           56  Coil 
           57  Insulating Base 
           58  Fixed-Side Insulation Substrate 
           59  Moving-Side Insulation Substrate 
           60  Electrodes 
           61  Electrets 
           62  Mover 
           63  Weight 
           645  Piezoelectric Body 
           70  Oscillatory Wave Generator 
           71   a  Metal Plate 
           71   b  Piezoelectric Body 
           72  Hammer 
           73  Fixed Case 
           74  Oscillatory Wave Conduction Medium 
           75  Small Gap 
           76   a ,  76   b  Oscillators 
           77  Oscillatory Wave Detector 
           79  Filter