Rolling bearing device

Abstract

A lubricating oil supply device (B) is provided with a tank (5) for holding lubricating oil (O), and a discharge machine (6) such as a pump provided with a discharge mechanism for discharging the lubricating oil supplied from the tank (5) into a bearing space between an inner ring (1) and an outer ring (2). A vent hole (10) for allowing the inside of the tank (5) and the bearing space to communicate with each other is opened in a wall surface of the tank (5). A swirling air flow generated in the bearing space is guided from the vent hole (10) into the tank (5), and the lubricating oil (O) is supplied from an oil supply passage (9) to the discharge machine (6) by the pressure of the air flow.

Description

Rolling bearing device

[0001] This invention relates to a rolling bearing device in which a lubricating oil supply device for supplying lubricating oil is attached to a rolling bearing.

[0002] Generally, as lubrication means for rolling bearings, air-oil lubrication, oil mist lubrication, etc. are adopted for rolling bearings that hold the main shafts of machine tools such as spindles for machine tools that require high-speed rotation (improvement of lubrication durability) instead of grease lubrication.

[0003] Air-oil lubrication and oil mist lubrication have injection ports and oil passages for supplying lubricating oil inside the bearing adjacent to the rolling bearing, and it is necessary to attach a supply device for compressed air and oil to the machine body to transfer the oil. These injection devices cause the machine body to become larger and increase the initial cost and operating cost.

[0004] Therefore, as a means for supplying lubricating oil to a rolling bearing that is small and does not require an injection device, a bearing device incorporating a lubricating oil supply unit is known. The lubricating oil supply unit includes a holding part for holding lubricating oil, a supply part for supplying lubricating oil from the holding part, and a power generation part for generating electric power, and operates a micropump with the electric power from the power generation part to supply lubricating oil inside the rolling bearing (Patent Document 1).

[0005] Also, as a diaphragm-type pump in a lubricating oil supply unit used for a rolling bearing device, a pump using a piezoelectric element in the drive part is known, and it is known that felt or sponge is provided in a tank for holding lubricating oil to hold the lubricating oil (Patent Document 2).

[0006] Also, in order to facilitate replenishment of lubricating oil, it is known to configure a lubricating oil tank with a flexible bag body capable of filling lubricating oil (Patent Document 3).

[0007] Furthermore, in high-speed rotating rolling bearings, a swirling airflow (swirling flow) is generated in the annular space between the outer and inner rings, and the oil droplets of the injected lubricating oil are easily repelled by the swirling flow. Therefore, there are known techniques to provide a windbreak of the required shape and to generate airflow in the required direction, so that as many oil droplets of lubricating oil floating around the nozzle that injects the lubricating oil as possible reach targets such as rolling elements and raceways (Patent Documents 4 and 5).

[0008] Patent No. 6495700 Patent No. 6446887 Patent No. 6054095 Patent No. 6750296 Patent No. 6677070

[0009] However, with the conventional technology described above, it is not easy to deliver a sufficient amount of lubricating oil droplets to the target. In order to efficiently deliver the oil droplets to targets such as rolling elements and tracks, it is necessary to increase the output of the oil supply mechanism, such as the pump. This requires larger pumps and more complex discharge mechanisms to improve the functionality of the discharge mechanism.

[0010] Furthermore, incorporating complex mechanisms and structures into the pump unit would require the entire lubrication unit and machinery to become larger, which would lead to higher manufacturing costs.

[0011] Therefore, the objective of this invention is to solve the above-mentioned problems, to provide a rolling bearing device that can discharge lubricating oil as efficiently as possible with a simple structure for the lubricating oil supply device attached to the rolling bearing, to accommodate miniaturization and simplification of the lubrication mechanism, and moreover, to provide a rolling bearing device that can efficiently and stably discharge lubricating oil in accordance with the rotational speed of the rolling bearing.

[0012] To solve the above problems, this invention provides a rolling bearing comprising a rolling bearing with a plurality of rolling elements interposed between an inner ring and an outer ring, and a lubricating oil supply device attached to the rolling bearing for supplying lubricating oil. The lubricating oil supply device comprises a tank for holding lubricating oil and a discharger equipped with a discharge mechanism for discharging the lubricating oil supplied from the tank into the bearing space between the inner ring and the outer ring of the rolling bearing. The rolling bearing device contains lubricating oil in the tank and has a ventilation hole that opens in the wall of the tank to connect the inside of the tank with the bearing space.

[0013] As described above, the rolling bearing device of this invention has ventilation holes opening in the wall of the tank that connect the inside of the tank and the bearing space. This allows the swirling flow generated by the rotation of the rolling bearing, which causes the air in the bearing space between the outer ring and the inner ring to swirl, to be taken into the tank through the ventilation holes.

[0014] As the air pressure inside the tank increases in response to the air pressure of the swirling flow taken in, the oil pressure of the lubricating oil contained in the tank is increased, and the pressurized lubricating oil is supplied to the discharge mechanism.

[0015] Furthermore, in order to allow as much of the swirling airflow generated in the bearing space by the rotation of the rolling bearing as possible to flow into the tank, it is preferable to provide an enclosure or duct at the opening edge of the ventilation hole opening into the wall surface to guide the airflow swirling around the axis in the bearing space from the opening into the tank.

[0016] Furthermore, the discharger may be a rolling bearing device comprising a discharge mechanism driven by an actuator, and a power source unit and a control unit for the actuator. The discharger may employ a well-known type of pump, or it may be a valve such as a pressure relief valve adjusted to open the discharge port at a pressure above a predetermined level, or it may be a discharger equipped with both such a pump and a valve.

[0017] The discharger is driven by actuators such as pistons, gears, and diaphragms, controlled by a power source and its control unit. By driving these actuators, it is possible to stably and consistently discharge the minimum necessary amount of lubricating oil from the discharge port into the bearing space, regardless of the rotational speed of the rolling bearing.

[0018] The amount of lubricating oil supplied to the discharger changes according to the pressure exerted on the lubricating oil by the airflow (swirling flow) corresponding to the rotational speed of the rolling bearing. Therefore, more lubricating oil is supplied at higher rotational speeds, and less or no lubricating oil is supplied at lower rotational speeds. In this way, the appropriate amount of lubricating oil, according to the rotational speed of the bearing, is supplied to the bearing space by an extremely simple adjustment mechanism.

[0019] The tank can also house a lubricating oil retaining member whose volume changes in response to changes in air pressure within the tank. This allows for the separation of the tank into areas containing lubricating oil and areas containing air pockets, and enables efficient application of air pressure to the lubricating oil by opening ventilation holes in the latter area.

[0020] As the above-mentioned lubricating oil holding member, it is also preferable to use a porous body or a bag-shaped container capable of holding lubricating oil. Such a lubricating oil holding member changes volume in response to changes in atmospheric pressure, that is, it contracts when pressurized, and the contracted volume of lubricating oil is supplied to the discharge mechanism.

[0021] If the lubricating oil holding member is a flexible porous body that is permeable to lubricating oil and has elasticity, the lubricating oil in the tank is held in place beforehand by capillary action within the pores of the porous body, and the volume of lubricating oil that has contracted due to air pressure against the elasticity of the porous body is supplied from the tank to the discharger.

[0022] Furthermore, if the lubricating oil holding member is a bag-shaped container capable of holding lubricating oil, the bag-shaped container, which is the lubricating oil holding member and whose volume changes in response to changes in atmospheric pressure, shrinks, causing the reduced volume of lubricating oil to flow out of the bag-shaped container into the tank and be supplied to the discharge mechanism.

[0023] Furthermore, it is preferable to provide one or more flow rate adjustment valves, selected from the oil supply passage that supplies lubricating oil from the tank to the discharger and the discharger itself, so that the amount of lubricating oil discharged by the discharger can be adjusted according to the operating conditions, purpose, or application of the rolling bearing device.

[0024] By providing a flow rate adjustment valve in the vent hole or the oil supply passage from the tank to the discharge mechanism, the amount of lubricating oil supplied to the discharger can be adjusted by adjusting the flow rate of the lubricating oil.

[0025] In this way, when the rolling bearing rotates at high speed, the amount of swirling flow taken into the tank can be adjusted to control the excessive supply of lubricating oil. Conversely, when the rolling bearing rotates at low speed, the flow control valve can be loosened to adjust the amount of oil supplied to the maximum possible.

[0026] This invention provides a ventilation hole in the wall of the tank that connects the inside of the tank of the rolling bearing device to the bearing space. This allows the lubricating oil supply device attached to the rolling bearing to have a simple structure while efficiently discharging an appropriate amount of lubricating oil. This enables miniaturization and simplification of the lubricating oil supply device, and also has the advantage of stably discharging an appropriate amount of lubricating oil corresponding to the rotational speed of the rolling bearing.

[0027] Axial cross-sectional view of the main part of the rolling bearing device of the first embodiment Cross-sectional view along line II-II in Figure 1 Block diagram illustrating the function of the lubricating oil supply device of the first embodiment Radial cross-sectional view of the main part of the rolling bearing device of the second embodiment Perspective view showing the main part of the rolling bearing device of the third embodiment Perspective view showing the vent holes of the tank of the rolling bearing device of the fourth embodiment Perspective view showing the vent holes of the tank of the rolling bearing device of the fifth embodiment Perspective view showing the vent holes of the tank of the rolling bearing device of the sixth embodiment Schematic explanatory diagram illustrating the operation of the flow rate adjustment valve

[0028] Embodiments of this invention will be described below with reference to the attached drawings. As shown in Figure 1-3, the first embodiment is a rolling bearing device applicable to mechanical devices used in high-speed rotation such as spindles for machine tools, and consists of an angular contact ball bearing A which has a cage 4 that holds the rolling elements 3, which are multiple balls, between an inner ring 1 and an outer ring 2, and allows the rolling elements 3 to rotate freely at regular intervals in the circumferential direction while being guided by the outer ring 2, and a lubricating oil supply device B which is attached in close contact with the axial end face of the outer ring 2 and supplies lubricating oil O.

[0029] As shown in Figures 1 and 2, the lubricating oil supply device B has the necessary components incorporated between the outer ring spacer B1 and the inner ring spacer B2 and fixed to the outer ring spacer B1. The lubricating oil supply device B includes a discharger (pump) 6 equipped with a discharge mechanism that discharges lubricating oil O supplied from the tank 5 into the bearing space between the inner ring 1 and the outer ring 2. The casing 8 of the discharger (pump) 6, which is equipped with a discharge nozzle 7, is in communication with the tank 5 via an oil supply passage 9. The oil supply passage 9 may be molded integrally with the casing 8 or the tank 5.

[0030] As shown in Figure 2, a ventilation hole 10 is opened in the wall of the end portion of the semicircular ring-shaped, cylindrical tank 5 that is away from the discharger 6, connecting the inside of the tank 5 to the bearing space. Inside the tank 5, which contains lubricating oil, is a lubricating oil holding member 12a made of a flexible porous material that changes volume in accordance with changes in air pressure inside the tank 5. This lubricating oil holding member (porous material) 12a holds a sufficient amount of lubricating oil O so that it seeps out due to its volume change.

[0031] Such ventilation holes 10 only need to be one or more, and the shape and number of holes may vary. For example, multiple elongated holes, such as slits, may be arranged in parallel, or each elongated hole may be partially covered by an overhang to guide airflow from a predetermined direction.

[0032] As shown in Figure 3, the discharger 6 leading to the tank 5 is equipped with a discharge mechanism such as a diaphragm or a positive displacement pump with a reciprocating piston and cylinder, and further includes an actuator 11 such as a piezoelectric element that drives the discharge mechanism, a power supply 13 which is its power source, and a microcontroller 14 which is its control unit.

[0033] The power supply mechanism of the power source unit 13 is arbitrary and may utilize, for example, a storage battery, a power supply connected to the outside of the lubricating oil supply device B, or electromotive force obtained by incorporating a power generation mechanism into the lubricating oil supply device B.

[0034] Furthermore, the power source unit 13, which uses a power supply, is connected to the control unit 14 and the actuator 11 so as to be able to supply power to them. The microcontroller of the control unit 14 is connected so as to be able to send commands to the actuator 11.

[0035] In the operating state of the rolling bearing device of the first embodiment configured in this way, when the rolling bearing A is rotating, the airflow generated in the bearing space (for example, the swirling flow shown by the arrow in Figure 2) flows into the tank 5 through the vent hole 10 formed in the part of the tank 5 that has an air reservoir on the end of the lubricating oil supply flow direction. Because the rolling bearing A is equipped with a cage 4 that holds the rolling elements 3, the airflow (swirling flow) generated by the rotation of the rolling bearing A is generated more sufficiently.

[0036] The rotational conditions of the rolling bearing device assumed in the embodiment can range from low speed to high speed, but for example, in the rotational state at high speed, the dn value is 70 × 10 ４ Preferably 110 x 10 ４ The above can be assumed. The upper limit of the dn value is not particularly limited, but for example, 200 × 10 ４ Preferably 180 × 10 ４ That is the case.

[0037] When the air pressure in the tank 5 increases due to the inflowing air, the lubricant holding member 12a accommodated in the tank 5 contracts due to the pressure received from the air flow, and the lubricant O corresponding to the contracted volume is supplied from the oil supply passage 9 to the discharge machine 6 composed of a pump. When only the lubricant O is accommodated in the tank omitting the lubricant holding member 12a, the lubricant O is directly supplied to the discharge machine 6 under the pressure from the air flow.

[0038] When the actuator 11 operates the discharge machine 6 such as a positive displacement pump based on a command from the control unit 14, the pressurized lubricant O is supplied to the discharge machine 6, so that the discharge operation is assisted and the discharge mechanism can be operated with less energy.

[0039] The lubricant such as the lubricant discharged from the discharge machine 6 in this way is discharged from the tip of the discharge nozzle 7 extending to the inside of the bearing space into the bearing space.

[0040] When the rolling bearing A is rotating its inner ring, the liquid lubricant O is discharged from the tip of the discharge nozzle 7, moves from the outer peripheral surface of the inner ring 1 (Fig. 1) to the raceway surface of the inner ring 1 by centrifugal force, and also lubricates the raceway surface of the outer ring 2 via the surface of the rolling element 3.

[0041] When mounted in the state where the outer ring 2 of the rolling bearing is fixed as in the first embodiment described above, if the air pocket a is always arranged at the upper part of the tank, the rolling bearing device can be used without accommodating the lubricant holding member 12a in the tank.

[0042] The actuator 11 described above can use, for example, a diaphragm applying a piezoelectric ceramic, a piston or a plunger reciprocating with a solenoid, or a mechanism combined with an electric motor. For a relatively large rolling bearing, a fluid pressure cylinder using air pressure or hydraulic pressure as a power source can also be adopted.

[0043] Specific examples of the discharge machine 6 include a pneumatically or hydraulically driven piston pump, a hydraulic pump such as a gear pump, a diaphragm pump, a rotary pump, etc. Also, a pump using an electric motor or a piezo element, for example, a micropump using a piezoelectric ceramic or the like may be used.

[0044] The lubricant holding member 12a can utilize materials such as a non-woven fabric having continuous gaps between densely packed fibers or a sponge having the property of sucking up into communicating pores so as to suck in the lubricant by capillary action.

[0045] Further, the lubricant holding member 12a may be formed of a soft and porous material that can be elastically deformed when pressed by the driving force of the actuator 11. For example, a material having communicating pores and elastic deformability such as a soft elastic rubber (elastomer) foam can be used. Representative examples of such materials include soft urethane foam, soft resin sponge, rubber sponge, felt, non-woven fabric, fiber filter material, and the like.

[0046] The lubricant used in this invention is not particularly limited, and a low-viscosity liquid lubricant that is liquid in the operating state of the rolling bearing and can be discharged from the discharge machine can be used.

[0047] That is, the lubricant can be a liquid lubricant according to the purpose of use of the rolling bearing device, but lubricating grease containing a thickener and separating oil with an external force or temperature rise, wax whose phase state changes from solid to liquid in the use environment, etc. can also be used.

[0048] The discharge amount of the lubricant is preferably an amount that does not affect the torque fluctuation of the rolling bearing by oil supply, and may be an extremely small amount. For example, 0.001 mL to 0.1 mL can be discharged using a micropump or the like. The discharge amount may be controlled such that the oil supply amount and the oil supply timing are adjusted according to the lubrication state of the rolling bearing A. The lubrication state may be detected by a sensor or the like provided inside or around the rolling bearing A, for example.

[0049] As shown in Figure 4, the lubricating oil supply device C used in the second embodiment is an example in which a lubricating oil holding member 12b, which is a bag-shaped container, is housed in the tank 5, instead of the lubricating oil supply device B used in the first embodiment. The lubricating oil holding member 12b is formed of a thin-walled sheet-like or film-like resin container so that its volume can change in response to changes in atmospheric pressure. In the second embodiment, the same configuration as the first embodiment is adopted, except that the lubricating oil holding member 12b, the external shape of the discharger 6a, and the shape (arrangement and length) of the discharge nozzle 7a are different.

[0050] The lubricating oil supply device D used in the third embodiment shown in Figure 5 expands the lubricating oil tank 5a used in the second embodiment to be as long as possible in the circumferential direction of the outer ring 2 to increase its capacity, and for this purpose, the control unit 14 and the power source unit 13 are arranged in parallel with the tank 5a. The components of this third embodiment other than the tank 5a are the same as those of the second embodiment.

[0051] Figure 6 shows the main part of a rolling bearing device as a fourth embodiment, in which a ventilation hole 10 is provided on the inner diameter surface side of the end of the tank 5 of the lubricating oil supply device. In yet another embodiment, a ventilation hole 10 provided on the end face of the tank 5 is shown by a dashed line. The ventilation hole 10 shown is one formed in the tank 5 of each embodiment, but two or more ventilation holes 10 may be provided in the required parts.

[0052] The fifth and sixth embodiment rolling bearing devices shown in Figures 7 and 8, respectively, have ventilation holes 10 in the tank, provided on the side surfaces of the end of the tank 5, and an arc-shaped airflow guide enclosure 15 (Figure 7) or an elbow-shaped duct 16 (Figure 8) is provided around the opening periphery of the ventilation hole 10.

[0053] By providing an annular airflow guide enclosure, such as an arc-shaped projection enclosure 15 or a duct 16, facing the direction opposite to the swirling flow, the airflow (swirling flow) can be efficiently taken into the tank 5 from the ventilation hole 10.

[0054] Furthermore, as shown in Figure 9, it is preferable to provide one or more flow rate adjustment valves 17, 18, and 19 selected from the vent hole 10, the oil supply passage 9 that supplies lubricating oil from the tank 5 to the discharger 6, and the discharge port of the nozzle 7 of the discharger 6, and to open and close these valves as appropriate and selectively.

[0055] This approach addresses the following problem: When a rolling bearing rotates at high speed, frictional heat causes the temperature of the inner ring 1 (see Figure 1) and the outer ring 2 to rise. The heat generated by the rising temperature of the inner ring 1 and outer ring 2 is transferred to the adjacent outer ring spacers B1 and inner ring spacers B2, causing the heated tank 5 to expand thermally, and the air a and lubricating oil O inside the tank 5 also attempt to expand thermally.

[0056] At this time, as shown in Figures 9(c) and 9(d), if the valve 18 of the fuel supply passage 9 is closed and the tank 5 is sealed, the internal pressure of the tank 5 will increase mainly due to the thermal expansion of the air. As a result, the tank 5 may be damaged, and as shown in Figure 9(d), gaps in the fuel supply mechanism that could not maintain airtightness, or lubricating oil O, may be forcibly pushed out from the discharge port of the discharge nozzle 7, leading to unintended oil leakage. To address these problems, it is necessary to keep the fuel supply passage 9, which connects the air a inside the tank 5 to the outside of the tank 5, open to prevent an increase in the internal pressure inside the tank 5.

[0057] Furthermore, as shown in Figure 9(c), when only the vent hole 10 is open and the fuel supply passage 9 is closed by the valve 18, the path from the vent hole 10 to the fuel supply passage 9 is blocked, so the swirling flow does not flow into the tank 5 from the vent hole 10.

[0058] Therefore, it is preferable that the vent hole 10, the oil supply passage 9 that supplies lubricating oil to the discharger, and the discharge port of the discharger 6 are all open. In this case, a portion of the swirling flow from the rolling bearing enters through the vent hole 10, and the lubricating oil O inside the tank 5 is pushed in the direction of discharge from the discharge port. As a result, the pushing force by the swirling flow, along with the discharge operation of the discharger 6, acts as an auxiliary to the pressure of the discharge operation, saving the energy required for the discharge operation.

[0059] Furthermore, a flow rate adjustment filter is provided in the vent hole 10 or the lubrication oil supply passage 9 from the tank 5 to the discharger 6, and the mesh size of the filter can be adjusted to separate gas and liquid or solid and liquid. In addition, the flow rate adjustment filter can release the pressure inside the tank 5 while preventing foreign matter and excess lubrication oil from flowing in from outside the tank 5, or it can allow only air or liquid above the required pressure to pass through the filter.

[0060] In the embodiments described above, an angular contact ball bearing applicable to a machine tool spindle was shown as an example of rolling bearing A. However, the rolling bearing in the rolling bearing device of this invention can also be a deep groove ball bearing, cylindrical roller bearing, tapered roller bearing, self-aligning roller bearing, needle roller bearing, thrust cylindrical roller bearing, thrust tapered roller bearing, thrust needle roller bearing, thrust self-aligning roller bearing, etc.

[0061] Furthermore, the rolling bearing device of this invention is not limited to the illustrated configuration. For example, the tank 5 may be extended in an annular shape to follow the entire circumference of the outer ring spacer B1, and the shape, material, and hardness of the tank are not particularly limited. The power source unit 13 and the control unit 14 may be arranged in any configuration within the space between the outer ring spacer B1 and the inner ring spacer B2, and the pump, tank, and other components constituting the lubricating oil supply device B may be placed inside the rolling bearing. In addition, protective partitions may be provided to prevent contact between the power source unit 13 and the control unit 14 and the inner ring spacer B2, or they may be covered with a casing.

[0062] 1 Inner ring 2 Outer ring 3 Rolling element 4 Cage 5, 5a Tank 6, 6a Discharger 7, 7a Discharge nozzle 8 Casing 9 Oil supply passage 10 Vent 11 Actuator 12, 12a, 12b Lubrication oil retaining member 13 Power source unit 14 Control unit 15 Enclosure 16 Duct 17, 18, 19 Valve A Rolling bearing B, C, D Lubrication oil supply device B1 Outer ring spacer B2 Inner ring spacer O Lubrication oil a Air reservoir

Claims

1. A rolling bearing device comprising a rolling bearing having a plurality of rolling elements interposed between an inner ring and an outer ring, and a lubricating oil supply device attached to the rolling bearing for supplying lubricating oil, wherein the lubricating oil supply device comprises a tank for holding lubricating oil and a discharger equipped with a discharge mechanism for discharging the lubricating oil supplied from the tank into the bearing space between the inner ring and the outer ring of the rolling bearing, the rolling bearing device having lubricating oil contained in the tank and ventilation holes opening into the wall surface of the tank.

2. The rolling bearing device according to claim 1, wherein an enclosure or duct is provided at the opening edge of the ventilation hole opening into the wall surface to guide the airflow swirling around the axis in the bearing space from the opening into the tank.

3. The rolling bearing device according to claim 1 or 2, wherein the discharge device is a discharge device using a pump, a valve, or both.

4. The rolling bearing device according to claim 3, wherein the discharger comprises a discharge mechanism driven by an actuator, and includes a power source unit and a control unit for the actuator.

5. The rolling bearing device according to claim 1 or 2, wherein a lubricating oil retaining member, whose volume changes in response to changes in air pressure inside the tank, is housed within the tank.

6. The rolling bearing device according to claim 5, wherein the lubricating oil holding member is a porous body or a bag-shaped container capable of holding lubricating oil.

7. The rolling bearing device according to claim 1 or 2, further comprising one or more flow rate adjustment valves selected from the above-mentioned vent hole, the above-mentioned oil supply passage for supplying lubricating oil from the above-mentioned tank to the above-mentioned discharger, and the discharger.

8. The rolling bearing device according to claim 3, further comprising one or more flow rate adjustment valves selected from the above-mentioned vent hole, the above-mentioned oil supply passage for supplying lubricating oil from the above-mentioned tank to the above-mentioned discharger, and the discharger.

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