Rolling bearing device

Abstract

The objective is to enable the temporary retention and stable discharge of the appropriate amount of lubricating oil in a lubrication device attached to a rolling bearing, and to ensure that the appropriate amount of lubricant is discharged stably and reliably using a simple lubrication mechanism. [Solution] A rolling bearing device comprising a rolling bearing A and a lubrication device B that supplies lubricant while being fixed in close contact with the axial end face of the outer ring 2, wherein the lubrication device B includes a tank for holding lubricant and a positive displacement pump 6 that discharges liquid lubricant supplied from the tank into the bearing space from a discharge nozzle 9, and the casing 8 of the positive displacement pump 6, which is driven by an actuator, is in communication with the tank by a lubrication passage 7, and a porous elastic body 10 that is permeable to lubricant is loaded into the casing 8.

Description

Technical Field

[0001] The present invention relates to a rolling bearing device provided with an oil supply device for supplying lubricating oil to a rolling bearing.

Background Art

[0002] Generally, as a lubrication means for a rolling bearing, it is known to enclose lubricating grease in an internal space between an outer ring and an inner ring at the time of assembling the bearing of the rolling bearing.

[0003] In normal grease lubrication, since lubrication is performed only with the initially enclosed grease, when a rolling bearing is used for high-speed rotation applications, the heat generation of the bearing accelerates the deterioration of the grease, and the lubricating oil required for the running part of the bearing becomes insufficient. Therefore, it is difficult to ensure lubrication durability.

[0004] Therefore, various lubrication technologies have been applied to rolling bearings that hold the main shafts of machine tools such as spindles for machine tools that require coping with high-speed rotation (improvement of lubrication durability). As lubrication methods suitable for such rolling bearings, air-oil lubrication, oil mist lubrication, etc. are adopted instead of grease lubrication.

[0005] Air-oil lubrication and oil mist lubrication are provided with injection ports and oil passages for supplying lubricating oil to the inside of 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.

[0006] Therefore, bearing devices incorporating a lubrication oil supply unit are known as a means of supplying lubricating oil to rolling bearings that are small and do not require an injection device. In some cases, a lubrication oil supply unit is combined with a grease-lubricated bearing and used to replenish the lubricating oil that is depleted in the rolling section. For example, a conventional lubrication oil supply unit comprises a holding section that holds the lubricating oil, a supply section that supplies the lubricating oil from the holding section, and a power generation section that generates electricity, and the electricity from the power generation section operates a micropump to supply lubricating oil to the inside of the rolling bearing (Patent Document 1).

[0007] Furthermore, a diaphragm-type pump used in a lubrication oil supply unit for a rolling bearing device is known to use a piezoelectric element in the drive unit, and it is known that felt or sponge is provided inside the tank that holds the lubricating oil to retain it (Patent Document 2, paragraph

[0028] ). [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Patent No. 6495700 [Patent Document 2] Patent No. 6446887 [Overview of the project] [Problems that the invention aims to solve]

[0009] However, the conventional lubrication oil supply units (lubrication devices) described above require control over the opening and closing of valves related to the pump and the discharge volume of the injection nozzle in order to prevent oil leakage and maintain strict airtightness of the pump, as well as the stable discharge of an appropriate amount of lubricating oil. In particular, with high-speed rotating rolling bearings, if excessive oil enters the rolling area, the heat generated by agitation can cause a rapid increase in the bearing's temperature, leading to bearing seizure. Similarly, if the amount of lubricating oil discharged is insufficient, the rolling area may not receive the necessary oil, which can also lead to seizure. On the other hand, incorporating complex mechanisms and structures to prevent oil leaks and insufficient airtightness in the pump unit leads to larger lubrication units and machinery, and consequently, higher manufacturing costs.

[0010] Therefore, the objective of this invention is to solve the above-mentioned problems and to enable the temporary retention of lubricating oil and the stable discharge of an appropriate amount in a lubrication device attached to a rolling bearing, and to enable the stable and reliable discharge of an appropriate amount of lubricant in the lubrication device with a simple mechanism. [Means for solving the problem]

[0011] To solve the above problems, this invention provides 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 lubrication device attached to the rolling bearing to supply lubricant, the lubrication device comprising a tank for holding lubricant, a positive displacement pump connected to the tank for discharging the supplied lubricant into the bearing space between the inner ring and the outer ring of the rolling bearing, a porous elastic body permeable to lubricant loaded in the casing of the positive displacement pump, an actuator for driving the positive displacement pump, a pressing body that presses a part or all of the porous elastic body permeated with lubricant within the casing with the driving force of the actuator to cause elastic deformation, and a power source unit and a control unit for the actuator.

[0012] As described above, the rolling bearing device of this invention has a porous elastic material with lubricant permeability loaded inside the casing of a positive displacement pump that discharges lubricant into the bearing space between the inner and outer rings of the rolling bearing. Therefore, the lubricant supplied from the tank connection can be retained in a state where it has permeated into the pores of the porous elastic material by capillary action.

[0013] When the porous elastic body is pressed by a pressing body using the driving force of the actuator that drives the positive displacement pump, the lubricant held in this manner deforms so that part or all of the porous elastic body elastically shrinks, and an amount of lubricant corresponding to the amount of shrinkage seeps out of the porous elastic body and can be discharged from the casing of the positive displacement pump.

[0014] Lubricant that is not discharged but held in the porous elastic material is retained within the casing by capillary action, even if the casing is not necessarily sealed. Therefore, lubricant does not leak out of the pump even without the installation of on-off valves or check valves at the connection point between the casing and the tank, or at the nozzles and discharge ports leading from the casing to the bearing space.

[0015] Furthermore, the required amount of lubricant can be discharged from the positive displacement pump into the bearing space simply by controlling the pressing force of the porous elastic body by the actuator that drives the positive displacement pump. Moreover, the casing and tank of the positive displacement pump do not need to be equipped with pressure adjustment or airtight / liquid-tight structures such as on-off valves or check valves; these can be provided as needed.

[0016] In this way, the rolling bearing device of this invention enables the stable and precise discharge of an appropriate amount of lubricant in the lubrication device using a simple mechanism.

[0017] Furthermore, in order to supply the lubricant held in the tank into the casing of the positive displacement pump as quickly and stably as possible, it is preferable that the porous elastic body extends from the casing of the positive displacement pump into the tank so that the lubricant permeability is continuous.

[0018] Furthermore, by loading the porous elastic material into the tank without any gaps, the lubricant is supplied from every corner of the tank into the casing of the positive displacement pump by capillary action, allowing for efficient and waste-free use of the lubricant in the tank of a predetermined capacity.

[0019] Also, by using a composite of a plurality of types of porous elastic bodies having different elastic forces and porosities as the porous elastic body, it is possible to adjust the supply rate of the lubricant to the positive displacement pump, the evaporation amount of the lubricating oil over time, the discharge amount of the lubricating oil, and the like.

Advantages of the Invention

[0020] In this invention, a porous elastic body having lubricant permeability is loaded into a casing of a positive displacement pump that is provided in a bearing space between an inner ring and an outer ring of a rolling bearing and discharges a lubricant, and a pressing body is provided to press this elastically deform by the driving force of an actuator. As a result, it becomes easier to temporarily hold the lubricant and discharge an appropriate amount of the lubricant by an oil supply device attached to the rolling bearing, and there is an advantage that an appropriate amount of the lubricant can be discharged stably and as surely as possible with a simple oil supply mechanism. There is also an advantage that the lubricant can be discharged in an arbitrary direction regardless of the attitude of the device.

Brief Description of the Drawings

[0021] [Figure 1] Axial sectional view of the main part of the rolling bearing device of the first embodiment [Figure 2] Cross-sectional view taken along line II-II of FIG. 1 [Figure 3] Block diagram for explaining the function of the oil supply device of the first embodiment [Figure 4] Schematic cross-sectional view of a positive displacement pump for explaining the function of the porous elastic body of the first embodiment [Figure 5] Schematic cross-sectional view of a positive displacement pump for explaining the function of the porous elastic body of the first embodiment [Figure 6] Schematic cross-sectional view of a positive displacement pump for explaining the function of the porous elastic body of the first embodiment [Figure 7] Schematic cross-sectional view of a positive displacement pump for explaining the function of the porous elastic body of the second embodiment [Figure 8] Schematic cross-sectional view of a positive displacement pump for explaining the function of the porous elastic body of the third embodiment [Figure 9] Schematic cross-sectional view of a positive displacement pump for explaining the function of the porous elastic body of the fourth embodiment [Modes for carrying out the invention]

[0022] Embodiments of this invention will be described below with reference to the attached drawings. As shown in Figures 1 to 6, the first embodiment is a bearing device applicable to mechanical devices used in high-speed rotation such as machine tool spindles, and consists of a rolling bearing A, which is an angular contact ball bearing, having a cage 4 that holds the rolling elements 3, which are multiple balls, between an inner ring 1 and an outer ring 2, so that they can rotate freely at regular intervals in the circumferential direction while being guided by the outer ring 2, and a lubrication device B that supplies lubricant O while being fixed in close contact with the axial end face of the outer ring 2.

[0023] As shown in Figures 1 and 2, the lubrication device B is incorporated between the outer ring spacer B1 and the inner ring spacer B2 and fixed to the outer ring spacer B1. It comprises a tank 5 that holds lubricant O and a positive displacement pump 6 that discharges the lubricant supplied from the tank 5 into the bearing space between the inner ring 1 and the outer ring 2. The casing 8 of the positive displacement pump 6 is in communication with the tank 5 via a lubrication passage 7. The lubrication passage 7 may be molded together with the casing 8 or the tank 5.

[0024] The casing 8 is provided with a discharge nozzle 9 capable of dispensing lubricating oil, and a porous elastic body 10 with lubricant permeability is loaded inside the casing 8. The porous elastic body 10 is loaded along the inner wall surface of the casing 8, and the portions where the oil supply passage 7 and discharge nozzle 9 open to the inner wall surface are also covered with the porous elastic body 10.

[0025] Furthermore, as shown in Figures 1 to 4, the refueling device B includes an actuator 11 such as a piezoelectric element that drives the positive displacement pump 6, and a pressing body (=push head) 12 that operates with the driving force of the actuator, as well as a microcontroller or the like as the power supply for the power source unit 13 of the actuator 11 and its control unit 14. The power supply mechanism for the power source unit 13 is arbitrary, and for example, it may utilize a storage battery, a power supply connected to the outside of the refueling device B, or electromotive force obtained by building a power generation mechanism in the refueling device B.

[0026] The pressing body 12 is connected to or integrated with the actuator 11 to appropriately press the porous elastic body 10, and by being connected to or integrated with, for example, a diaphragm or a reciprocating piston, it can repeatedly perform the operation of contacting and pressing the porous elastic body 10, and then moving away from the porous elastic body 10.

[0027] In addition, the bearing space between the inner ring 1 and the outer ring 2, which are made of iron-based metal material, may be filled with the required amount of lubricating grease in the appropriate places depending on the bearing application, and sealing members 15 may be attached to one or both axial ends of the bearing space, however, depending on the bearing application, it may be not necessary to fill it with lubricating grease.

[0028] As shown in Figures 2 and 3, a power source unit 13 using 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 control unit 14, for example, uses a microcontroller and is connected so as to be able to send commands to the actuator 11.

[0029] When the actuator 11 operates the positive displacement pump 6 based on a command from the control unit 14, part or all of the porous elastic body 10 impregnated with lubricant, which is loaded into the casing 8 of the positive displacement pump 6, is pressed and compressed by the press 12, or comes into contact with or separates from the press 12 without being subjected to the pressing force.

[0030] As shown in Figures 4-6, when the pressing body 12 presses the porous elastic body 10 containing lubricant O, the pressing force pushes the lubricant O out of the porous elastic body 10, and the pushed-out liquid lubricant O is discharged into the bearing space from the tip of the discharge nozzle 9, which extends into the bearing space. Note that the discharge nozzle 9 may be configured in any shape as appropriate, rather than being a tube shape as shown in Figure 1.

[0031] For example, when the rolling bearing A is rotating its inner ring, liquid lubricant O is discharged from the tip of the discharge nozzle 9, moves along the raceway surface of the inner ring 1 (Figure 1) by centrifugal force from the outer surface of the inner ring 1, and lubricates the raceway surface of the outer ring 2 via the surface of the rolling element 3.

[0032] The amount of liquid lubricant O discharged can be adjusted by the displacement of the pressing body 12 driven by the actuator 11, the pressing force, the pressing area and volume, the diameter and shape of the nozzle hole, and so on. The driving state of the actuator 11 is controlled by the control unit 14.

[0033] When the pressing body 12 is driven in the opposite direction to the pressing direction, the pressing force at the contact surface of the porous elastic body 10 with the pressing body 12 is reduced or becomes negative. Due to capillary action of the porous elastic body 10 or the pressure difference with the inside of the tank 5, the porous elastic body 10 swells while absorbing the liquid lubricant O. At this time, air a may also be drawn into the porous elastic body 10, but the air a moves to the inside of the tank 5 via the oil supply passage 7 in a gas-liquid exchange. In the lubrication device B (Figure 1), these operations and actions are repeated to continuously or in a timely manner draw lubricant O from tank 5 (Figure 5) and discharge it into the bearing space.

[0034] Furthermore, since the porous elastic body 10 is held in a state of being impregnated with lubricant by capillary force, it is possible to discharge the lubricant from the discharge nozzle 9 in any direction, for example, it is possible to discharge the lubricant in a direction against gravity.

[0035] The actuator 11 described above can, for example, use a mechanism that combines a piston or plunger that reciprocates using a diaphragm or solenoid made of piezoelectric ceramic, and an electric motor. For relatively large rolling bearings, a fluid pressure cylinder powered by pneumatics or hydraulics can also be used.

[0036] The positive displacement pump 6 only needs to have a pressing body 12, and may use not only a reciprocating pump but also a rotary pump. The pressing body 12 installed in the chamber can also be operated by the fluid pressure generated by a gear pump or the like.

[0037] Specific examples of positive displacement pumps 6 include pneumatically or hydraulically driven piston pumps, hydraulic pumps such as gear pumps, and diaphragm pumps. Pumps using electric motors or piezoelectric elements, such as micropumps using piezoelectric ceramics, may also be used.

[0038] The porous elastic body 10 can be made of a nonwoven fabric with continuous gaps between densely packed fibers, allowing it to absorb lubricant through capillary action, or a material that has the property of drawing lubricant into interconnected pores, like a sponge. Furthermore, the porous elastic body 10 is made of a material that is soft and porous enough to be elastically deformable when pressed by the driving force of the actuator 11, and can be made of a material that has interconnected pores and is elastically deformable, such as a soft elastic rubber (elastomer) foam. Typical examples of such materials include flexible polyurethane foam, flexible resin sponges, rubber sponges, felt, nonwoven fabrics, and fiber filter materials.

[0039] As a lubricant, liquid lubricating oil suitable for use with rolling bearings can be used at room temperature. However, lubricating grease containing thickeners that separates with external force or temperature rise, or waxes whose phase state changes from solid to liquid with temperature changes can also be used as lubricants.

[0040] The amount of lubricant, such as lubricating oil, dispensed is preferably such that it does not affect the torque fluctuations of the rolling bearing, and may be an extremely small amount. For example, 0.001 mL to 0.1 mL can be dispensed using a micropump or the like. The amount dispensed may be controlled according to the lubrication state of the rolling bearing A, and the amount and timing of lubrication may be controlled accordingly. The lubrication state may be detected, for example, by a sensor installed inside or around the rolling bearing A.

[0041] In Figures 1 and 2 illustrating the first embodiment, an angular contact ball bearing applicable to a machine tool spindle is 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.

[0042] Furthermore, the rolling bearing device of this invention is not limited to the illustrated configuration. For example, the tank 5 may be extended in a circular shape along the entire circumference of the outer ring spacer B1, the power source unit 13 and the control unit 14 may be arranged in any way within the space between the outer ring spacer B1 and the inner ring spacer B2, and the pump, tank, etc. that constitute the lubrication 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, etc., and the inner ring spacer B2, or they may be covered with a casing.

[0043] Furthermore, the rolling bearing device of this invention exhibits excellent lubrication durability even under high-speed rotation conditions, enabling long-term use. High-speed rotation conditions include, for example, a dn value of 70 × 10⁻⁶. 4 The above, preferably 110 × 10 4 The above can be assumed. The upper limit of the dn value is not particularly limited, but for example, 200 × 10 4 And, 180 × 10 4 That is the case.

[0044] In the second embodiment shown in Figure 7, the porous elastic body 10 is extended and loaded so as to be continuous from inside the casing 8 into the tank 5, and the other main components are substantially the same as those of the first embodiment.

[0045] However, in the second embodiment, due to the gas-liquid exchange phenomenon that occurs after the discharge of the liquid lubricant O, air a that flows back from the discharge nozzle 9 tends to accumulate in the tank 5. Therefore, a vent hole 16 for releasing the air is provided in the tank 5 along with a check valve 17. The check valve 17 is preferably provided to avoid the risk of the lubricant O being pushed out by atmospheric pressure and leaking from the discharge nozzle 9 even when the pressing body 12 is not pressurizing the porous elastic body 10.

[0046] The third embodiment shown in Figure 8 is provided in which the porous elastic body 10 is installed not only in the casing 8 but also inside the tank 5 without any gaps, and the other main components are the same as in the first embodiment. The porous elastic body 10 can be installed inside the tank 5 by combining multiple pieces of the same or different materials, and each surface or part of them is configured to overlap or come into contact with one another.

[0047] By loading the porous elastic body 10 into the tank 5 without any gaps in this manner, the lubricant can permeate the porous elastic body 10 from every corner of the tank 5, and the lubricant in the tank 5 can be used without any waste.

[0048] Furthermore, if the inside of the tank 5 is completely filled with the porous elastic body 10, the lubricant is held in place by the capillary force of the porous elastic body 10, and when the lubricant is discharged from the discharge nozzle 9, gas-liquid exchange occurs within the porous elastic body 10. Therefore, a vent hole may be provided in the tank 5 to promote the movement of gas and liquid. Also, as in the second embodiment, a vent hole may be combined with a check valve.

[0049] The fourth embodiment shown in Figure 9 illustrates an example where the porous elastic body 10 is a composite material made up of multiple types of porous elastic bodies 10, 10a, and 10b made of different materials with varying elasticity and porosity, while the other main components are the same as in the first embodiment.

[0050] When combining multiple porous elastic bodies 10, 10a, and 10b, it is possible to combine materials with different elasticity, porosity, and other properties, i.e., different compositions and densities. In this way, the supply rate of lubricant to the positive displacement pump 6, the amount of lubricant that evaporates over time, and the amount of lubricant discharged can be adjusted.

[0051] For example, if porous elastic bodies 10a and 10b made of foam having interconnected pores are placed in the tank 5, and a porous elastic body 10 made of a fibrous molded body is placed in the casing 8 of the pump 6, the amount of lubricant discharged can be adjusted by slowing down the movement of the lubricant with the porous elastic bodies 10a and 10b made of foam with a low porosity, while drawing out a sufficient or appropriate amount of lubricating oil from the porous elastic body 10 made of a fibrous molded body. In addition, vents may be provided in the tank 5, and as in the second embodiment, vents and check valves may be combined in the tank 5.

[0052] As described in the first to fourth embodiments of this invention, the rolling bearing device is discharged into the rolling bearing A via the porous elastic body 10, so the lubricant does not leak out to the outside even without providing on-off valves or check valves at the connection between the casing 8 and the tank 5, or at the discharge nozzle 9 or oil supply passage 7 leading from the casing 8 to the bearing space.

[0053] Furthermore, malfunctions caused by insufficient airtightness in the pump mechanism are less likely to occur, air-only discharge (so-called "dry firing") can be prevented, and the amount of lubricant discharged can be adjusted by the arrangement and combination of the porous elastic body 10. Furthermore, it is sufficient that the lubricant is temporarily held in the porous elastic body 10 during the discharge operation, and since the lubricant can be discharged in a direction against gravity, the lubricant can be discharged in any direction regardless of the orientation of the device. Therefore, the appropriate amount of lubricant is dispensed from the lubrication device B as reliably as possible using a simple lubrication mechanism.

[0054] The base oil of the lubricating grease sealed in the bearing space and the lubricant supplied from the tank are not particularly limited, but it is preferable that the lubricant supplied from the tank be the same as, or has a similar composition to, the base oil of the lubricating grease sealed in the bearing space, and that use an oil type that has high affinity with the base oil or an oil with a kinematic viscosity close to that of the base oil. [Explanation of Symbols]

[0055] 1 Inner ring 2 Outer ring 3 Rolling element 4 Cage 5 tanks 6. Positive displacement pumps 7. Fueling route 8 Casing 9. Discharge nozzle 10, 10a, 10b Porous elastic material 11 Actuators 12 Pressing body 13 Power source section 14 Control Unit 15 sealing member 16 ventilation holes 17 Check valve A Rolling bearing B Fueling device B1 Outer wheel spacer B2 Inner Wheel Spacer O Lubricant a air

Claims

1. A rolling bearing having multiple rolling elements interposed between the inner and outer rings, This consists of a lubrication device attached to the rolling bearing that supplies lubricant, The aforementioned lubrication device includes a tank for holding lubricant, A positive displacement pump discharges the lubricant supplied from this tank into the bearing space between the inner and outer rings of the rolling bearing. A porous elastic material with lubricant permeability is loaded inside the casing of this positive displacement pump, An actuator that drives the aforementioned positive displacement pump, A pressing body that presses a part or all of a porous elastic body permeated with lubricant within the casing with the driving force of the actuator to cause elastic deformation, A rolling bearing device comprising a power source unit and a control unit for the actuator.

2. The rolling bearing device according to claim 1, wherein the casing of the above-mentioned positive displacement pump is a casing that communicates with the tank and the oil supply passage.

3. The rolling bearing device according to claim 2, wherein the porous elastic body is a porous elastic body loaded so as to be continuous from inside the casing into the tank.

4. The rolling bearing device according to claim 3, wherein the porous elastic body is a porous elastic body packed without any gaps inside the tank.

5. The rolling bearing device according to any one of claims 1 to 4, wherein the porous elastic material is a composite of multiple types of porous elastic materials having different elastic forces and porosity.

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