Bearing device

A bearing device is constituted by a rolling bearing and a lubricant supply device combined with each other. The lubricant supply device includes a lubrication oil tank which stores pressurized lubrication oil and has a lubrication oil discharge spout; an open/close valve which opens/closes the lubrication oil discharge spout of the lubrication oil tank; a driving section which operates the open/close valve; and an electric power source section which generates electric energy for operation of the driving section. The lubricant supply device is attached to the rolling bearing or to a spacer adjacent thereto.

BACKGROUND OF INVENTION

Technical Field

The present invention relates to bearing devices used in machine tools, industrial machinery, etc., and particularly to a bearing device constituted as a combination of a bearing and an oil supply unit.

Background Art

A bearing device which incorporates an oil supply unit therein is conventional (see Patent Literature 1). This bearing device is a rolling bearing and an oil supply unit is mounted on an inner diameter surface of one of two mutually opposed track rings, or a fixed-side track ring in this case. The oil supply unit includes a tank which stores lubrication oil; a pump which pumps out the lubrication oil stored in the tank into the bearing; and an electric generator which drives the pump. The device also includes means which controls the pump based on bearing conditions thereby controlling an amount of discharged oil. Patent Literature 2 shows another bearing device which includes a similar oil supply unit.

Patent Literature 3 shows a rolling bearing device, in which a lubrication oil tank of the oil supply unit is detachable/attachable and is mounted between a fixed-side track ring and a rotation-side track ring. The oil supply unit has a casing which serves as the lubrication oil tank.

All of these conventional examples described above have a shared arrangement that the lubricant is supplied to the bearing by a pump which is a constituent component of the oil supply unit.

CITATION LIST

Patent Literature

TECHNICAL PROBLEM

The oil supply unit which makes use of a pump has the following problems: First, there is a lead time before the pump attains a pressure capable of discharging the oil, after the pump is started. In addition, each individual pump has a different capacity for supplying lubrication oil, and therefore individual adjustment is necessary. Further, electric energy is converted into mechanical, rotary energy in order to drive the pump. This means energy efficiency is low.

SUMMARY OF INVENTION

Therefore, a first object of the present invention is to provide a rolling bearing device which includes an oil supply unit capable of supplying the lubrication oil from a lubrication oil tank to the rolling bearing without utilizing a pump, without a time lag, and at a high level of energy efficiency.

Next, rolling bearing devices which include conventional oil supply units have such a construction that the oil supply unit is assembled into a space between a fixed-side track ring and a rotation-side track ring of the rolling bearing, and for this reason the fixed-side track ring and the rotation-side track ring must be of a special width and shape, i.e., standard track rings are not usable. This leads to management complication in manufacturing the rolling bearings, resulting in increased cost.

Also, when replenishing lubrication oil to the lubrication oil tank in the oil supply unit, the entire rolling bearing must be removed from, e.g., a spindle housing of a machine tool. Further, since the casing of the oil supply unit also serves as the lubrication oil tank, the oil supply unit must be removed from the rolling bearing after the rolling bearing was removed, in order for the lubrication oil to be added. In other words, replenishing the lubrication oil requires many steps and is time consuming.

In addition, since the casing of the oil supply unit also serves as the lubrication oil tank, there has been no such option as having a replacement lubrication oil tank ready in advance.

Therefore, a second object of the present invention is to provide a rolling bearing device which does not require a special fixed-side track ring nor a special rotation-side track ring of special width and shape, and does not require removal of the rolling bearing when replenishing the lubrication oil tank with lubrication oil.

Next, in rolling bearing devices which include conventional oil supply units, the pump sucks up the lubrication oil from the lubrication oil tank and discharges the oil through a pump discharge piping, into the bearing. The amount of oil supply is controlled by the pump operation time.

However, when the pump is stopped after completing the lubrication oil supply, the pump and the discharge piping are filled with lubrication oil, and there is siphoning of lubrication oil from the lubrication oil tank into the discharge piping. The lubrication oil leaks out of the nozzle, causing oversupply of lubrication oil, resulting in increased stirring resistance of the lubrication oil.

As a result, it is impossible to obtain a stable lubrication environment, and there is additional problem of heat generation.

Therefore, a third object of the present invention is to provide a rolling bearing device which is capable of performing appropriate supply of lubrication oil from the lubrication oil tank of the oil supply unit.

SOLUTION TO PROBLEM

In order to achieve the first object, the present invention provides a bearing device comprising a rolling bearing and a lubricant supply device combined with each other, in which the lubricant supply device includes: a lubrication oil tank which stores pressurized lubrication oil and has a lubrication oil discharge spout; an open/close valve which opens/closes the discharge spout of the lubrication oil tank; a driving section which operates the open/close valve; and an electric power source section which generates electric energy for operation of the driving section. With this, the lubricant supply device is attached to the rolling bearing or to a spacer adjacent thereto.

The lubrication oil loaded in the lubrication oil tank is pressurized by a pressurizer which presses the oil with a pressurizing spring.

Alternatively, lubrication oil is discharged from a nozzle of the open/close valve by a pressure from a weight of lubricant which is stored in the lubrication oil tank.

Next, in order to achieve the second object, the present invention provides a bearing device comprising a rolling bearing and a lubricant supply device combined with each other, in which the lubricant supply device is attached to a spacer adjacent to the rolling bearing, and at least includes an lubrication oil tank which has a lubrication oil discharge spout, a pump, a driving section, and an electric power source section. With the above, the lubrication oil tank is provided by an elastic bag.

The bag which constitutes the lubrication oil tank is made of a resin film, by placing a sheet of the resin film on another and thermally welding perimeters.

Next, in order to achieve the third object, the present invention provides a bearing device comprising a rolling bearing and a lubricant supply device combined with each other, in which the lubricant supply device 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 spout; a driving section which operates the pump; an electric power source section which supplies the driving section with electric energy; and a leakage prevention mechanism which is disposed at a discharge piping of the pump for preventing leakage of lubrication oil. With the above, the lubricant supply device is attached to a fixed-ring-side member of the rolling bearing or to a spacer adjacent to the rolling bearing.

Examples of the leakage prevention mechanism include an open/close valve provided in the discharge piping of the pump arranged in such a fashion that the open/close valve will be opened only during oil supply operation. Another example is an arrangement that upon completion of oil supply by operating the pump, the pump is operated in reverse thereby introducing air into the discharge piping.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention which achieves the first object, unlike those which use a pump in supplying lubrication oil, there is no time lag before lubrication oil supply because lubrication oil supply is made by the open/close valve which opens/closes the discharge spout of the lubrication oil tank which stores pressurized lubrication oil.

Also, energy efficiency is improved over those which use pumps because lubricant supply is achieved by opening/closing the open/close valve.

According to the present invention which achieves the second object, there is no need for utilizing a special fixed-side track ring nor a special rotation-side track ring of special width and shape. Further, it is possible to replenish the lubrication oil tank with lubrication oil without removing the rolling bearing.

According to the present invention which achieves the third object, the bearing device is capable of preventing the problem that lubrication oil inside the pump and discharge piping is siphoned into the discharge piping, causing leakage of the lubrication oil from the nozzle end, resulting in oversupply of lubrication oil when the pump is stopped after completion of lubrication oil supply.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be described based on the attached drawings. In the following description of embodiments, parts and components having the same construction will be indicated by the same alpha-numerical reference symbols, without repeating description thereof when appropriate, to avoid redundancy.

A rolling bearing device10embodies a solution to the first object of the present invention; namely, this bearing device includes an oil supply unit13which is capable of supplying lubrication oil A from a lubrication oil tank39to a rolling bearing11without time lag and without using a pump, and at a high level of energy efficiency. This embodiment, i.e., the rolling bearing device10will now be described with reference toFIG. 1throughFIG. 4.FIG. 1shows a machine tool which incorporates the rolling bearing devices10.

The bearing device10according to the embodiment shown inFIG. 1throughFIG. 4includes a rolling bearing11; a spacer12press-contacted onto an axial end of the rolling bearing; and an oil supply unit13incorporated in the spacer12; and when used, is assembled into a space between a rotation shaft14and a housing15. The rolling bearing11has another end, on which another spacer16is press-contacted. These two spacers12,16provide axial positioning of the rolling bearing11. The rotation shaft14is placed horizontally. In cases where the rotation shaft14is horizontal, the bearing device10is called upright type.

The rolling bearing11includes track rings provided by an inner ring17and an outer ring18; a predetermined number of rolling elements19placed between the track rings; and a retainer21which keeps a predetermined distance between the rolling elements19. The rolling bearing11is an angular contact ball bearing. In the figures, the outer ring18serves as a fixed-side track ring.

The spacer12includes an inner-ring-side spacer12aand an outer-ring-side spacer12b. The inner-ring-side spacer12ais fitted in and fixed to the rotation shaft14side and is press-contacted onto an end of the inner ring17. The outer-ring-side spacer12bis fitted in and fixed to an inner diameter surface of the housing15, and is press-contacted onto an end of the outer ring18. In the same fashion, the other spacer16is fitted in and fixed to the rotation shaft14side and the housing15side, and is press-contacted onto the other ends of the inner ring17and of the outer ring18. Thus, the rolling bearing11is preloaded at a predetermined pressure.

The oil supply unit13is constituted by an annular, plastic casing24which is mounted on an inner diameter surface of the outer-ring-side spacer12b, and various members incorporated inside the casing. The oil supply unit13is mounted on an inner diameter surface of the outer ring18if the outer ring18is wide in its width. In this case, the spacer12serves only as a spacer. As shown in the figures, in the present embodiment, the oil supply unit13is mounted to the spacer12.

As shown inFIG. 3andFIG. 4, the casing24has a U-shaped section, with an open end facing away from the rolling bearing11, and to this open end, an annular lid25is attached detachably therefrom/attachably thereto. On a side away from this open end side, along a corner region made by an inner end surface26and an outer circumferential surface27of the casing24, an outward protruding guide28is provided all around the circumference. The guide28is assembled into a stepped portion29which is at a shoulder region in an inner diameter surface of the outer ring18of the rolling bearing11. The outer ring18has a partial track groove31as a cutout made by the stepped portion29.

The spacer12which is provided with the oil supply unit13is left-right symmetric.FIG. 2is a view when the spacer12on the right side inFIG. 1is viewed from an axial direction.

Along an inner circumferential surface of the fixed-side outer-ring-side spacer12bin the spacer12, a lubrication oil tank39which stores lubrication oil A is provided.

The lubrication oil tank39has a discharge nozzle38via an open/close valve37. The lubrication oil tank39has a pressurizer80for pressurizing the lubrication oil A. When the open/close valve37is opened, a pressurizing force from the pressurizer80causes the lubrication oil A from inside the lubrication oil tank39to be discharged from the discharge nozzle38, and when the open/close valve37is closed, the discharge of the lubrication oil A stops.

For example, the pressurizer80may be provided by a type shown inFIG. 3, in which lubrication oil A loaded in the lubrication oil tank39is pressed by a pressurizing spring82via a pressurizing seal plate81.

Lubrication oil A discharged from the lubrication oil tank39has a discharge pressure which is determined by the pressure exerted by the pressurizer80to the lubrication oil tank39if the nozzle size of the discharge nozzle38is constant. Therefore, by controlling the pressure of the pressurizer80in accordance with the type of lubrication oil A, it is possible to send the lubrication oil A from the lubrication oil tank39at a constant pressure.

The discharge nozzle38is inserted into an inner circumferential surface of the fixed-ring-side outer ring18of the rolling bearing11, and supplies the lubrication oil A discharged from the discharge nozzle38to surfaces of the balls19or to the track groove35.

The discharge nozzle38may be a spray nozzle which sprays lubrication oil A in an atomized form. Since this decreases stirring resistance caused by lubrication oil A, it is possible to reduce heat generation in the rolling bearing11.

The amount of lubrication oil A discharged from the discharge nozzle38can also be controlled by changing valve opening degree in the open/close valve37.

Next,FIG. 5throughFIG. 8show an embodiment, which is the same rolling bearing device10as the embodiment shown inFIG. 1throughFIG. 4in that it is capable of supplying lubrication oil A from a lubrication oil tank39to a rolling bearing11without time lag and without a pump; however, in this present embodiment, discharge pressure of lubrication oil A is not created by the pressurizer80, but lubrication oil A is guided to the open/close valve37by the weight of the lubrication oil A.

As shown inFIG. 6, a discharge hole36is formed at a border region between an inner diameter surface33and the inner end surface26of the guide28. When the casing24is assembled into the inner diameter surface of the outer ring-side spacer12b, the casing24is positioned so that this discharge hole36will be at the lowest position during operation. The casing24is made of plastic or metal.

The casing24incorporates therein various parts and components of the oil supply unit13as shown inFIG. 7, including an open/close valve37which is provided by a normally closed solenoid valve; a pair of left and right tanks39; and an electric power source section41of a driving section40.

The open/close valve37is placed at a position which represents the lowest position during the use, i.e., a region including the discharge hole36. The open/close valve37has a nozzle38at its low position. The nozzle38is inserted obliquely through the discharge hole36so that the nozzle38has its discharge spout38afacing down (seeFIG. 5andFIG. 6). The discharge spout38aconsequently reaches a point which is close to the track groove35in the inner diameter surface of the guide28.

The pair of lubrication oil tanks39are housed detachably/attachably on both sides of the open/close valve37, at positions higher than the nozzle38. Each tank39has its lower end connected to the open/close valve37via a connection pipe42. The open/close valve37and the tanks39may be integrated with each other, in which case, the connection pipes42are not needed.

Each tank39has an opening in its upper end, to which a stop plug43is fitted. The stop plug43is removed when loading the tank39with lubrication oil. During normal operation, the opening is closed to prevent lubrication oil leakage. However, if these openings are closed completely, a partial vacuum will be developed inside the tanks39and inhibit discharge of lubrication oil. Thus, an air vent44(seeFIG. 8) is formed, and to this air vent44, a filter45, which allows air to pass through but does not allow lubrication oil, is attached. The filter45is made of a porous-continuous resin material, for example.

In the embodiment shown inFIG. 1throughFIG. 4and in the embodiment shown inFIG. 5throughFIG. 8, the open/close valve37is opened/closed by the driving section40, the driving section40is operated by the electric power source section41, and these two components are disposed between the outer ring-side spacer12band the inner ring-side spacer12aof the spacer12, like the lubrication oil tank39.

In the embodiment shown inFIG. 5throughFIG. 8, the driving section40and the electric power source section41are disposed between upper ends of the tanks39. Power supply between the driving section40and the electric power source section41, and between the driving section40and the open/close valve37is provided via cables (not illustrated) routed inside the casing24.

As shown inFIG. 9, the driving section40has sensors such as a bearing temperature sensor46, a bearing rotation sensor47, a lubricant remaining quantity sensor48, and a lubricant temperature sensor49. Signals from these sensors are inputted to a CPU51, which then automatically controls the open/close valve37in terms of degree of opening and time for which the valve is opened, in accordance with temperature and rotation status of the rolling bearing11, thereby controlling the amount of lubricant supply.

The open/close valve37, the driving section40and the electric power source section41constitute a discharge amount adjuster65for the lubricant discharged from the open/close valve37(seeFIG. 9).

The electric power source section41is provided by dry batteries, rechargeable batteries, or a self-contained power generator. As the self-contained power source the following options may be used. Specifically, the electric power source section41shown inFIG. 10includes heat conductors52,53which are provided to penetrate the outer circumferential surface27and the inner circumferential surface30of the casing24respectively; and a Seebeck element placed between these heat conductors52,53.

The electric power source section41may be provided by a power generating device which makes use of Seebeck effect as described above. In this arrangement, when the rolling bearing device10is operating, temperature of the inner ring17and the outer ring18increases due to friction heat with the rolling elements19. In general configuration, the outer ring18is assembled into the housing15of the machine it serves, and therefore loses heat by thermal conduction, resulting in temperature difference between the inner and the outer rings17,18. Different temperatures conducted to the respective heat conductors52,53causes the Seebeck element54to have temperature difference between its two end surfaces, causing the element to generate electric power based on Seebeck effect.

When using the above configuration where heat conductors52,53are provided to penetrate the inner circumferential surface and the outer circumferential surface of the casing24respectively and a Seebeck element54is placed between these heat conductors52,53, it is preferable that an adhesive which takes heat conductivity well into account should be used on a surface where the heat conductor52which penetrates the outer circumferential surface of the casing24makes contact with the inner diameter surface of the outer ring-side spacer12b.It should be noted here that the heat conductor52which is on the outer ring side has an outer diameter which is equal to an inner diameter of the outer ring-side spacer12band is fitted thereto for improved heat radiation. On the other hand, the heat conductor53which is on the inner ring side has its inner diameter surface not in contact with the inner ring-side spacer12a. If possible, it is desirable that the outer ring-side and the inner ring-side heat conductors52,53have the same volume.

Preferably, thermal grease, for example, should be applied between the inner diameter surface of the outer ring-side spacer12band the heat conductor52; between the heat conductor52and the Seebeck element54; and between the Seebeck element54and the inner-ring-side heat conductor53, for improved contact and heat conductivity. Thermal grease generally contains silicone as a primary ingredient. The heat conductors52,53should 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.

In addition to those which generate electric power based on the Seebeck effect as described above, the electric power source section41can also be provided by those shown inFIG. 11,FIG. 12andFIG. 13.

The one inFIG. 11is applicable in cases where there is an alternating magnetic field inside the bearing device10. There is leakage flux or high-frequency wave radiation inside a build-in spindle incorporated in machine tools for example, or near high-frequency wave equipment which handles a large amount of electric power. This leakage flux is utilized to generate electric power based on electromagnetic induction. Specifically, an E-shaped iron core55which has an open end on one side is combined with a coil56for efficient capture of the alternating magnetic field and power generation based on electromagnetic induction. An insulation base57is attached to the open surface of the iron core55. If the leakage flux has a known frequency, then the iron core55may be eliminated while the coil56is configured to resonate with the frequency of the leakage flux.

The one shown inFIG. 12is applicable in cases where there is vibration inside the rolling bearing device10. When vibration occurs in the rolling bearing device10, a rubbing device62causes a moving-side insulation substrate59to vibrate in a direction indicated by an arrow “a”. In this process, relative movement between a fixed-side and the moving-side insulation substrates58,59and an electret61generate electric charge between electrodes60based on electrostatic induction. This electric charge is taken out to obtain electric power.

The one shown inFIG. 13is applicable also in cases where there is vibration inside the rolling bearing device10. Specifically, an elastic sheet of piezoelectric body64is disposed between a fixed-side insulation substrate58and a weight63. When vibration occurs in the rolling bearing device10, interaction between the weight63and the piezoelectric body64causes the weight63to vibrate in a direction indicated by an arrow “a”. In this process, the piezoelectric body64is twisted, to generate electromotive force based on dielectric polarization. This electromotive force is taken out to obtain electric power.

The electric charge generated by the power generation section41is stored in a power storage section such as a battery and a capacitor. If a capacitor is employed, an electric double layer condenser (capacitor) is desirably used.

One bearing device10according to one embodiment was covered with reference toFIG. 1throughFIG. 4while the other according to another embodiment was covered with reference toFIG. 5throughFIG. 8thus far. Both of them have their tanks39of their respective oil supply units13filled with lubrication oil A and the lid25closed before use.

As the rotation shaft14rotates, the sensors such as the bearing temperature sensor46, the bearing rotation sensor47, the lubricant remaining quantity sensor48, the lubricant temperature sensor49pick up and send signals to a CPU51. Based on these signals, the CPU51provides automatic control on opening degree and time of the open/close valve37, thereby optimizing lubrication. The lubrication oil A is provided by lubrication oil or low-viscosity grease.

In the embodiment shown inFIG. 5throughFIG. 8, the filter45which allows air to pass through keeps an atmospheric air pressure inside the tank39. Therefore, the lubrication oil A flows due to a weight of the lubricant itself through the nozzle38and then out of the tip, i.e., the discharge spout38a. The discharged lubricant moves along the inner diameter surface33of the guide28and is supplied to the track groove35(seeFIG. 6). The pressure for discharging the lubrication oil A is obtained only from the weight of the lubrication oil A in the tank39.

FIG. 14shows a spindle70in a machine tool, for example, which utilizes the bearing devices10according to the embodiment shown inFIG. 5throughFIG. 8. The spindle70has its rotation shaft71placed horizontally.

The rotation shaft71has an intermediate region formed with a large diameter section72, which has an outer diameter surface with an axial end formed with a flange73, and another axial end formed with a thread74. Between the flange73and the thread74, two bearing devices10are installed to sandwich a middle spacer75in between.

One of the bearing devices10is positioned at a location on an inner side of the flange73and of another flange77which faces radially thereto at an end of the spindle housing76. The other bearing device10is positioned at a location on an inner side of a nut78which is threaded around the thread74and of a flange79which faces thereto on another end of the spindle housing76.

The bearing device10on the flange73side and the bearing device10on the thread74side are disposed symmetrically with each other, with the rolling bearing11being disposed on the middle spacer75side (inner side) and the spacer12being disposed on the outer side.

As the rotation shaft71rotates, lubrication oil A is supplied due to a weight of the lubricant oil itself, from the discharge spout38aof the nozzle38to the track groove35of the rolling bearing11in the same manner in the two bearing devices10.

The bearing device10shown inFIG. 15is a horizontal type attached to a rotation shaft14which is disposed vertically. Basic arrangement is the same as the upright type except that there is a 90-degree orientation change.

In this case, in the embodiment according toFIG. 5throughFIG. 8, the tank39is in a horizontal attitude. Therefore, the nozzle38of the open/close valve37is provided on a bottom surface of the open/close valve37so that it is at the same or a lower height than the bottom surface of the tank39, in order that lubrication oil will discharge from the tank39due to a weight of the lubricant. Also, the spacer12, which includes the oil supply unit13, is disposed at a higher level while the rolling bearing11is disposed at a lower level so that the discharged lubrication oil will drop onto a predetermined spot in the rolling bearing11. The stop plug43of the tank39is provided in an upper end wall surface of the tank39.

Since the lubrication oil discharged from the discharge spout38aof the nozzle38is reliably supplied by its weight to inside of the rolling bearing11located beneath, there is no need for providing the guide28(seeFIG. 15) which is in the embodiment inFIG. 14. Rather, it is enough if the discharge spout38ais at an upper region of the gap between the inner ring17and the outer ring18of the rolling bearing.

In the embodiment inFIG. 15, the nozzle38is slanted outward in order to supply lubricant to the track groove35in the outer ring17of the rolling bearing11. In cases where lubricant should be supplied to the track groove50of the inner ring18, inward slanting will be used as shown inFIG. 16.

FIG. 17shows an embodiment in which a spindle70has its rotation shaft71disposed vertically. The bearing device10is disposed at two locations, i.e., an upper location and a lower location. In the upper bearing device10, the spacer12is at an upper position while the rolling bearing11is at a lower position. In the lower bearing device10, the oil supply unit13is assembled to the middle spacer75, and the rolling bearing11is therebelow. The spacer12at the lowest end is hollow.

Next, a rolling bearing device10embodies a solution to the second object of the present invention; namely, this bearing device does not require a special, fixed-side track ring18, nor a special, rotation-side track ring17of special width and shape, and does not require removal of the rolling bearing when replenishing the lubrication oil tank39with lubrication oil. Description of the rolling bearing device10will be made with reference toFIG. 18throughFIG. 24. The rolling bearing11is pre-packed with desirable grease, and a seal plate22is attached to an end on the spacer16side.

As shown inFIG. 20, the oil supply unit13includes an annular casing24, which incorporates therein such components as an electric power source section41, a driving section40, a pump83, a lubrication oil tank39, etc. in a circumferential direction.

The casing24has a lid25, which is fixed to the casing24with a screw24a. By removing the screw24aand removing the lid25, it becomes possible to replenish the lubrication oil tank39, which is incorporated inside the casing24, with lubrication oil without removing the entire oil supply unit13.

As shown inFIG. 19, the annular casing24of the oil supply unit13has a generally U-Shaped section, with an open surface facing away from the rolling bearing11. This opening in the casing24is closed with the lid25which is detachable therefrom/attachable thereto. The casing24and the lid25are made of the same thermally plastic resin material such as PPS.

The casing24has its outer circumferential surface adhesively fixed to the inner diameter surface of the outer ring-side spacer12b, with an adhesive. The adhesive for fixing the casing24is provided by epoxy resin for example.

FIG. 21shows an embodiment in which the casing24is fixed without using an adhesive, to the inner diameter surface of the outer ring-side spacer12b.

In this example inFIG. 21, a pair of recesses12c,12dreceding in an outer diameter direction are formed on both axial sides of an inner diameter surface of the outer ring-side spacer12b;the casing24has an outer diameter surface on the rolling bearing11side, where there is formed a ridge24bto fit into the recess12c, and this ridge24bis fitted into the recess12c;the other recess12dis fitted by an outer diameter portion of the lid25which is fixed to the casing24with the screw24a, so that the lid25is screw-fixed to the casing24by the screw24a. Thus, the inner diameter surface of the outer ring-side spacer12bis sandwiched by the ridge24bof the casing24and the outer diameter portion of the lid25, thereby fixing the casing24to the inner diameter surface of the outer ring-side spacer12b, without using an adhesive.

Next, a lubrication oil tank39is incorporated inside the casing24, is provided by a bag39aof an elastic resin and is disposed in an arcuate form along the annular casing24.

As shown in an enlarged view inFIG. 22, the plastic bag39ais, for example, made of a resin film, by placing a sheet of the resin film on another, and then thermally welding their perimeters. InFIG. 22, a reference symbol39bindicates the thermally welded region.

The bag39ais provided with a suction tube83awhich leads to the pump83. The suction tube83ais integrated with the bag39aby sandwiching the tube between two films of resin when forming the bag39a, and then performing the thermal welding to complete the bag39a.

FIG. 23shows a bag39awhich is formed by blow molding. If the bag39ais formed by blow molding, it is possible to form the suction tube83aand the bag39aintegrally with each other.

Desirably, however, the bag39aof the lubrication oil tank39formed by blow molding should receive a flattening process to modify a bag portion since the bag portion is bulged in the blow molding process. By altering the shape of the bag into a flattened bag, the bag becomes possible to discharge lubrication oil completely even after the amount of the lubrication oil has become small. This way, it is possible to completely consume the lubrication oil stored in the bag39a.

The bag39awhich constitutes the lubrication oil tank39can be formed of such a material as polyamide (for example, polyamide11and polyamide12), fluorine-containing rubber (FKM), polyamide elastomer, polyethylene, polyester and polypropylene; however, there is no specific limitation to the material as far as the material is compatible with lubrication oil stored in the bag39a.

It is desirable that the suction tube83awhich is provided in the bag39aof the lubrication oil tank39is detachable from the pump83. The suction tube83awhich is detachable from the pump83allows the suction tube83ato be removed from the pump83for replenishing lubrication oil A from the suction tube83ainto the bag39awhen lubrication oil level becomes low in the lubrication oil tank39.

Also, the bag39awhich is detachable from the pump83allows such a replacement system that lubrication oil A is loaded in a replacement bag39a, and when there is no more lubrication oil A left in the original bag39a, then the used bag39ais taken out and is replaced with the replacement bag39a. In this way, replenishing lubrication oil A can be finished within a short time. Since the replacement bag39acan be loaded with lubrication oil under a controlled environment at a lubrication oil manufacturer, it is possible to reduce such a risk as foreign matter inclusion in the bag39aat the time of loading oil. It should be noted here that a lid should desirably be placed to the suction tube83aof the replacement bag39ain order to prevent foreign matter inclusion during storage.

Lubrication oil A which is loaded in the bag39aof the lubrication oil tank39desirably has a viscosity of VG22 for example, since an excessively high viscosity will be a too much burden on the pump and the power source.

Next,FIG. 24shows another embodiment. In this embodiment, there is no need for removing the bag39aout of the casing24or removing the lid25when replenishing the bag39aof the lubrication oil tank39with lubrication oil A, i.e., it is possible to fill the bag39awith lubrication oil A while the bag39astays inside the casing24.

As shown inFIG. 24, a through-hole85is made radially, from an outer circumferential surface of the housing15in which the rolling bearing device10is installed, to inside of the casing24in the oil supply unit13. When replenishing lubrication oil A, a lubrication oil syringing needle86is inserted through the through-hole85into the bag39ainside the casing24, to fill the bag39awith the lubrication oil A. A lubrication oil injection port88which is made of a highly elastic rubber is provided at a place in the bag39awhere the lubrication oil syringing needle85will be inserted so that insertion/removal of a needle tip87of the lubrication oil syringing needle86will not cause leakage of lubrication oil.

The housing15in which the rolling bearing device10is installed, the spacer12, the radial through-hole made in the casing24of the oil supply unit13, and the lubrication oil injection port87in the bag39aare circumferentially aligned with each other at the time of assembling.

In the embodiment described above, the annular casing24incorporates, in addition to the lubrication oil tank39, an electric power source section41, an driving section40, an pump83, etc., in its circumferential direction.

The pump83has a suction tube83awhich sucks lubrication oil from the lubrication oil tank39; and a discharge tube83bfrom which the sucked lubrication oil is discharged. The discharge tube83bhas a discharge nozzle 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 bearing11.

It is possible, for example, to operate the pump83upon a timing when the electric power, which comes from the electric power source section41and is stored in a capacitor in the power storage section, has reached a predetermined voltage. If the power is charged too quickly in relation to power generation efficiency, the power may be discharged to a resistor for example, upon a time when a predetermined power storage voltage has been reached thereby introducing an interval in the operation timing of the pump83. In this case, there is a cycle (s) of charging and discharging before the pump83is operated. The number of this charge-discharge cycles can be used in controlling the operation interval of the pump83. Alternatively, a timer function may be triggered when the power storage voltage has reached a predetermined value, to provide an interval in the operation timing of the pump83. In this case, the above-described charge-discharge cycle is not repeated.

As shown inFIG. 25, for example, the driving section40has sensors such as a bearing temperature sensor46, a bearing rotation sensor47, a lubricant remaining quantity sensor48, and a lubricant temperature sensor49. Signals from these sensors are inputted to a CPU51, which then automatically controls the pump43in accordance with temperature and rotation status of the rolling bearing11, thereby controlling the amount of lubricant supply. InFIG. 25, a reference symbol41aindicates a power storage section.

The suction tube83a, which is connected to the suction side of the pump83, extends into the lubrication oil tank39to suck lubrication oil stored in the lubrication oil tank39.

On the other hand, the discharge tube83bwhich is connected to the discharge side has its tip connected to a discharge nozzle for discharging lubrication oil into the rolling bearing. It is desirable that the discharge nozzle has its tip disposed at a location between the inner and the outer rings of the bearing, closely to the inner ring's outer circumferential surface. The discharge nozzle's nozzle hole has an appropriately designed inner diameter based on a relationship between surface tension due to base oil viscosity and the amount of discharge.

It should be noted here that the above embodiment is an example of inner ring rotation, and. Also, it has a horizontal rotation axis; however, the axis may be vertical. Further, it may be incorporated in a machine tool spindle.

Next, a rolling bearing device as a solution to the third object of the present invention will be described; namely, this embodiment is capable of eliminating the problem that when the pump83is stopped after completion of lubrication oil supply, the pump83and discharge piping are filled with lubrication oil A, and there is siphoning of lubrication oil A into the discharge piping, causing leakage of the lubrication oil A from the nozzle end, resulting in oversupply of lubrication oil. The description will be made with reference toFIG. 26throughFIG. 32.

First, the lubrication oil tank39which is incorporated inside the casing24is provided by a bag39aof an elastic resin, and is disposed in an arcuate form along the annular casing24.

The bag39ahas a suction tube83awhich leads to the pump83. The suction tube83acan be integrated with the bag39aby sandwiching the tube between two films of resin when forming the bag39aand then performing thermal welding to complete the bag39a.

Also, if the bag39ais formed by blow molding, it is possible to form the suction tube83aand the bag39aintegrally with each other.

The bag39awhich constitutes the lubrication oil tank39can be formed of such a material as nylon, polyethylene, polyester and polypropylene; however there is no specific limitation to the material as far as the material is compatible with lubrication oil stored in the bag39a.

Lubrication oil which is loaded in the lubrication oil tank39desirably has a viscosity of VG22 for example, since an excessively high viscosity will bear a too much burden on the pump and the power source.

The pump83has a suction tube83awhich sucks lubrication oil A from the lubrication oil tank39; and a discharge tube83bfrom which the sucked lubrication oil is discharged. The discharge tube83bhas a discharge nozzle83cat its tip, from which lubrication oil is supplied to between the fixed-side track ring and the rotation-side track ring of the rolling bearing11.

The pump83is driven to suck lubrication oil A from the lubrication oil tank39; and the lubrication oil is supplied to between the fixed-side track ring and the rotation-side track ring of the rolling bearing11from the discharge nozzle83cat the tip of the discharge tube83b. After a predetermined amount of the lubrication oil is supplied, the pump83is stopped.

Even when the pump83is stopped, the pump83and discharge piping are filled with lubrication oil, and there can be siphoning of lubrication oil from the lubrication oil tank39, causing lubrication oil leakage from the discharge nozzle83c. The present invention has a leakage prevention mechanism in the discharge piping of the pump83to prevent the leakage of lubrication oil.

Examples of the leakage prevention mechanism includes, as shown inFIG. 28, an open/close valve84provided in the discharge tube83bso that the open/close valve84will be opened only while the pump83is in operation and the open/close valve84will otherwise be closed. Another example is an arrangement that upon completion of oil supply by operating the pump83, the pump83is operated in reverse thereby introducing air into the discharge piping.

Examples of the open/close valve84include a sequence valve84awhich operates mechanically to open the flow path upon exceeding a predetermined pressure; and a solenoid valve84bwhich electrically opens/closes the flow path.

FIG. 29shows a hydraulic circuit for a case where the open/close valve84is provided by the sequence valve84a.FIG. 30shows a hydraulic circuit for a case where the open/close valve84is provided by the solenoid valve84b.

The solenoid valve84band the pump83can be controlled in an integrated manner.

When the pump83is stopped after the pump83was operated to perform an oil supply, the suction tube83aand the pump83are still filled with lubrication oil, and as indicated by an arrow in alternate long and short dash lines inFIG. 31, there is siphoning of lubrication oil from the lubrication oil tank39, into the discharge tube83b, resulting in lubrication oil leakage from the discharge nozzle83c. In order to prevent this leakage, in the present invention, the pump83is reverse operated after discharging lubrication oil. As the pump83is reversed and air is introduced into the discharge tube83band the pump83as indicated by an arrow in an alternate long and short dash lines inFIG. 32, lubrication oil comes under an increased pipe resistance, which prevents leakage caused by siphoning.

Next, timing when lubrication oil is supplied, i.e., timing when the pump83is operated, can be when the electric power, which is stored in a capacitor in a power storage section41a, has reached a predetermined voltage. If power charge time is too short in relation to power generation efficiency, the power may be discharged to a resistor for example, upon a time when predetermined power storage voltage has been reached, thereby introducing an interval in the operation timing of the pump83. In this case, there is a cycle(s) of charging and discharging before the pump83is operated. The number of this charge-discharge cycles can be used in controlling the operation interval of the pump83. Alternatively, a timer function may be triggered when the power storage voltage has reached a predetermined value, to provide an interval in the operation timing of the pump83. In this case, the above-described charge-discharge cycle is not repeated.

The suction tube83a, which is connected to the suction side of the pump83, extends into the lubrication oil tank39to suck lubrication oil stored in the lubrication oil tank39.

On the other hand, the discharge tube83bwhich is connected to the discharge side has its tip connected to a discharge nozzle83cfor discharging lubrication oil into the rolling bearing. It is desirable that the discharge nozzle83chas its tip disposed at a location between the inner and the outer rings of the bearing, closely to the inner ring's outer circumferential surface. The discharge nozzle83chas a nozzle hole appropriately designed inner diameter based on a relationship between surface tension due to base oil viscosity and the amount of discharge.

REFERENCE SIGNS LIST