Bearing unit and method for replacing lubricant in bearing unit

Abstract

To provide a bearing unit in which grease to a bearing can be easily supplied and replaced, and which is thereby stably usable over a long period of time while securing the service life of the bearing itself to the maximum, and a method for replacing a lubricant.SOLUTION: A bearing unit 1 has a bearing 4 received in a bearing reception portion 9 of a housing 2, and comprises: a first bearing cover 5 and a second bearing cover 6, which are attached to the housing 2 with the covers respectively covering both sides of the bearing reception portion 9; a first lubricant discharge pipe 17 extending outward from the first bearing cover 5 for discharging a lubricant in the bearing 4 from a first discharge port 17b; and a second lubricant discharge pipe 27 extending outward from the second bearing cover 6 for discharging the lubricant in the bearing 4 from a second discharge port 27c. A first openable / closable air vent 17c is provided at the tip of the first lubricant discharge pipe 17, and a second openable / closable air vent 27c is provided at the tip of the second lubricant discharge pipe 27.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a bearing unit that rotatably supports a shaft, such as a hoist, and a method for replacing a lubricant in the bearing unit, for example.

Background Art

[0002] Conventionally, as this type of bearing unit, for example, the one described in Patent Document 1 previously filed by the present applicant is known. This bearing unit is configured by assembling a bearing into a bearing housing and rotatably supports a horizontally extending rotating shaft. The above bearing is of a double-row type having two rows of rolling elements between an inner ring and an outer ring, and both side surfaces between the inner ring and the outer ring are sealed by a pair of shields. Further, this bearing unit has a ventilation structure that allows air to enter and exit inside and outside the bearing, and an oil supply structure that allows grease as a lubricating oil to be replenished into the bearing.

[0003] The ventilation structure includes a bearing housing ventilation hole provided so as to extend vertically at the upper part of the bearing housing, a ventilation groove provided so as to extend over the entire circumferential direction on the outer peripheral surface of the outer ring of the bearing and communicating with the bearing housing ventilation hole, and a plurality of outer ring ventilation holes penetrating the outer ring at the bottom of the ventilation groove and arranged at predetermined intervals from each other in the circumferential direction of the ventilation groove. Through these bearing housing ventilation holes, ventilation grooves, and outer ring ventilation holes, air can enter and exit inside and outside the bearing. On the other hand, the oil supply structure has a bearing housing oil supply hole provided so as to extend in a state slightly inclined with respect to the horizontal near the vertical center of the bearing housing. In this bearing housing oil supply hole, a grease nipple is attached to the outer end thereof, while the inner end communicates with the ventilation groove of the outer ring.

[0004] In the bearing unit described above, grease is pre-sealed inside the bearing to enhance its lubrication, allowing the inner ring and integrated shaft to rotate smoothly relative to the outer ring fixed to the bearing housing. Furthermore, if the grease decreases due to prolonged use of the bearing unit, causing poor rotation of the shaft, grease is replenished into the bearing via the lubrication structure described above. Specifically, a grease gun or similar device is connected to the grease nipple, and grease is injected under pressure into the lubrication hole in the bearing housing. This grease is then replenished into the bearing by passing through the lubrication hole in the bearing housing, the ventilation groove in the outer ring, and the ventilation hole in the outer ring. In this case, the air inside the bearing is discharged to the outside of the bearing unit through the ventilation structure, thereby allowing grease replenishment without increasing the internal pressure of the bearing. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2015-96737 [Overview of the project] [Problems that the invention aims to solve]

[0006] In the bearing unit described above, it is possible to replenish the grease inside the bearing. Therefore, by replenishing the grease when it decreases, the service life of the bearing unit can be extended. However, since the bearing described above is a double-row type with two rows of rolling elements, if, for example, the replenished grease is more abundant on one row of rolling elements and less abundant on the other, the degree of grease filling inside the bearing may become uneven between the rows of rolling elements. In such cases, it may become impossible to obtain sufficient lubrication from the bearing.

[0007] Furthermore, grease is generally composed of a semi-solid paste-like substance in which a thickener with a three-dimensional structure is dispersed in a base oil consisting of mineral oil or synthetic oil. The thickener acts like a sponge, holding the base oil in place. However, with prolonged use of the bearing unit, the grease deteriorates due to a decrease in the thickener's ability to hold the base oil and a decrease in the base oil itself, resulting in a reduction in its lubricating performance. Therefore, although new grease is replenished in the bearing as described above, the bearing unit in question faces the following problems.

[0008] In other words, because deteriorated grease remains in the bearing, there is a risk that the newly added grease may not be able to perform its intended lubrication due to mixing with the deteriorated grease. Of course, it is conceivable to replace the grease in the bearing by removing the deteriorated grease and then adding new grease. However, replacing the grease in the above bearing unit requires removing the bearing unit from the rotating shaft, and then removing the shield from the bearing to remove the deteriorated grease, which is a very complicated and time-consuming process. Therefore, there is room for improvement in the above bearing unit.

[0009] The present invention was made to solve the above-mentioned problems, and aims to provide a bearing unit that can be used stably for a long period of time while ensuring the maximum lifespan of the bearing itself, by easily supplying and replacing lubricants such as grease to the bearing, and a method for replacing the lubricant in the bearing unit. [Means for solving the problem]

[0010] To achieve the above objective, the invention according to claim 1 is a bearing unit comprising a housing having a bearing housing portion that penetrates in a predetermined direction, and a bearing housed in a fitted state in the bearing housing portion and rotatably supporting a shaft extending along a predetermined direction, wherein the bearing has an outer ring whose outer surface is in close contact with the circumferential surface of the bearing housing portion, an inner ring disposed inside the outer ring and fixed to the shaft with the shaft passing through it, and a plurality of rolling element rows, each consisting of a plurality of rolling elements arranged circumferentially between the outer ring and the inner ring, and a ring-shaped ring groove is formed on at least one of the circumferential surface of the bearing housing portion and the outer surface of the outer ring, opening toward the other and extending along the circumferential direction and formed over the entire circumferential direction, the housing has a lubricant supply passage that communicates the ring groove with the outside and supplies lubricant to the bearing from the outside, and the outer ring has a ring groove that communicates with the inner circumferential surface of the outer ring and along the circumferential direction of the outer ring The bearing comprises: first and second bearing covers, which are attached to a housing and prevent leakage of lubricant, and are arranged at predetermined intervals from each other, and have a plurality of lubricant introduction holes for introducing lubricant supplied to the ring groove to the inner circumferential surface side of the outer ring, through which the shaft passes and covering the bearing housing from both sides; a first lubricant discharge pipe, which is provided to extend outward for a predetermined length from a predetermined part of the first bearing cover and discharges the lubricant inside the bearing to the outside from a first discharge port at its tip; and a second lubricant discharge pipe, which is provided to extend outward for a predetermined length from a predetermined part of the second bearing cover and discharges the lubricant inside the bearing to the outside from a second discharge port at its tip, wherein the tip of the first lubricant discharge pipe is provided with an openable and closable first vent hole that connects the inside and outside of the first lubricant discharge pipe, and the tip of the second lubricant discharge pipe is provided with an openable and closable second vent hole that connects the inside and outside of the second lubricant discharge pipe.

[0011] In this configuration, a bearing having multiple rows of rolling elements is housed in a bearing housing portion of the housing, and first and second bearing covers are attached to the housing so as to cover the bearing housing portion from both sides. The first bearing cover is provided with a first lubricant discharge pipe extending outward from a predetermined portion thereof, while the second bearing cover is provided with a second lubricant discharge pipe extending outward from a predetermined portion thereof. The first and second lubricant discharge pipes are provided with a first and second discharge port at their respective ends, and furthermore, the ends of each are provided with a first and second vent hole that can be opened and closed, allowing communication between the inside and outside.

[0012] In the bearing unit configured as described above, when supplying lubricant to the bearing, the lubricant is injected from outside the bearing unit into the lubricant supply passage of the housing. This injected lubricant is supplied to a ring groove formed on at least one of the circumferential surface of the bearing housing portion of the housing and the circumferential surface of the outer ring of the bearing, and is further introduced to the inner circumferential surface side of the outer ring through a plurality of lubricant introduction holes provided in the outer ring. As a result, the lubricant is filled into the space between the outer ring and the inner ring, around each rolling element, and in the space between both sides of the bearing and the first and second bearing covers. In a bearing unit filled with lubricant in this way, even if the internal pressure of the bearing rises due to the temperature rise caused by use, the rise in internal pressure of the bearing can be suppressed because the inside of the bearing is vented to the atmosphere through the first and second vent holes provided in the first and second lubricant discharge pipes, respectively. This prevents leakage of lubricant from the first and second bearing covers while ensuring smooth rotation of the inner ring relative to the outer ring.

[0013] Furthermore, in a bearing unit in which lubricant is filled into the bearing, if the lubricant inside the bearing deteriorates due to long-term use of the bearing unit, the deteriorated lubricant inside the bearing can be replaced with new lubricant by performing the lubricant replacement method for bearing units described later.

[0014] As described above, the bearing unit of the present invention makes it easy to supply and replace lubricant into the bearing, thereby ensuring the maximum lifespan of the bearing itself in the bearing unit and enabling stable use over a long period of time.

[0015] The invention according to claim 2 is characterized in that, in the bearing unit described in claim 1, the plurality of rolling element rows are composed of two sets of rolling element rows.

[0016] With this configuration, since two sets of rolling element rows are used as the multiple sets of rolling element rows in the bearing, the bearing unit can be constructed more easily and inexpensively compared to using a relatively common general-purpose bearing and a bearing with three or more sets of rolling element rows.

[0017] The invention according to claim 3 is characterized in that, in the bearing unit described in claim 2, each of the plurality of lubricant introduction holes is provided so as to be located between two sets of rolling element rows.

[0018] With this configuration, since each of the multiple lubricant introduction holes is located between the two sets of rolling element rows, when supplying lubricant to the bearing unit, the lubricant introduced from each lubricant introduction hole to the inner circumferential surface of the outer ring can be supplied into the bearing while flowing relatively evenly to both sets of rolling element rows.

[0019] The invention according to claim 4 is characterized in that, in the bearing unit described in claim 3, the lubricant supply passage is provided in the upper part of the housing so as to extend in the vertical direction.

[0020] With this configuration, a lubricant supply passage for supplying lubricant from the outside is provided extending vertically at the top of the housing. By injecting lubricant from the upper end of the lubricant supply passage, the lubricant can be easily filled into the bearing unit by flowing from the top to the bottom of the bearing using its own weight.

[0021] The invention according to claim 5 is the bearing unit according to claim 4, wherein the first lubricant discharge pipe is configured such that its proximal end is provided at the lower part of the first bearing cover and extends at a right angle to the shaft and horizontally, and the second lubricant discharge pipe is configured such that its proximal end is provided at the lower part of the second bearing cover and extends at a right angle to the shaft and horizontally.

[0022] According to this configuration, the first and second lubricant discharge pipes are each configured to extend a predetermined length at a right angle to the shaft and horizontally from the lower parts of the corresponding first and second bearing covers. That is, the first and second discharge ports at the respective distal ends of the first and second lubricant discharge pipes are provided so as to be away from the shaft. Therefore, when replacing the lubricant, etc., it is possible to relatively easily recover the lubricant while avoiding the lubricant discharged from the discharge ports of each lubricant discharge pipe from adhering to the shaft.

[0023] The invention according to claim 6 is the bearing unit according to claim 1, further comprising a vent hole opening / closing device that is connected to the first vent hole and the second vent hole respectively and is configured to normally open the first vent hole and the second vent hole to the atmosphere, and to close one of the first vent hole and the second vent hole and open the other of the first vent hole and the second vent hole to the atmosphere when supplying the lubricant.

[0024] According to this configuration, by simply operating the vent hole opening / closing device connected to the first vent hole and the second vent hole, the first vent hole and the second vent hole can be opened and closed as described above, and it is possible to easily switch the opening / closing states of the first vent hole and the second vent hole during normal use of the bearing unit and when supplying the lubricant.

[0025] The invention according to claim 7 is a method for replacing lubricant in a bearing unit according to any one of claims 1 to 6, comprising: a first lubricant supply and discharge step of supplying new lubricant to the bearing via a lubricant supply passage and discharging deteriorated lubricant from the first discharge port, while opening the first discharge port and first vent hole of a first lubricant discharge pipe and closing the second discharge port and second vent hole of a second lubricant discharge pipe; and a second lubricant supply and discharge step of supplying new lubricant to the bearing via a lubricant supply passage and discharging deteriorated lubricant from the second discharge port, while opening the second discharge port and second vent hole of a second lubricant discharge pipe and closing the first discharge port and first vent hole of the first lubricant discharge pipe, after the discharge of deteriorated lubricant from the first discharge port is complete.

[0026] According to this configuration, in the bearing unit described in any of claims 1 to 6, the deteriorated lubricant already filled in the bearing (hereinafter referred to as "deteriorated lubricant" in this section as appropriate) is replaced with new lubricant (hereinafter referred to as "new lubricant" in this section as appropriate) in the following manner. First, the first outlet and first vent of the first lubricant discharge pipe are opened, and the second outlet and second vent of the second lubricant discharge pipe are closed. Then, while maintaining this state, new lubricant is supplied through the lubricant supply passage of the housing. In this case, the internal pressure increases in the space between the second bearing cover and the bearing near the base end of the second lubricant discharge pipe, which has a closed second outlet and second vent, while the internal pressure does not increase in the first lubricant discharge pipe, which has an open first outlet and first vent, and the lubricant flows in easily.

[0027] Therefore, as described above, with the first discharge port and the first vent hole open and the second discharge port and the second vent hole closed, a new lubricant is supplied to the lubricant supply passage by pressing or the like, so that the inside of the bearing and the space between the first bearing cover and the bearing are filled with the new lubricant, and the deteriorated lubricant inside the bearing is sent to the first lubricant discharge pipe while being pressed by the new lubricant and discharged to the outside through the first discharge port (first lubricant supply and discharge process). And after the discharge of the deteriorated lubricant from the first discharge port is completed, the opening and closing states of the first and second discharge ports and the first and second vent holes are reversed.

[0028] That is, the second discharge port and the second vent hole are opened, and the first discharge port and the first vent hole are closed. And in this state, a new lubricant is supplied again through the lubricant supply passage. As a result, the space between the second bearing cover and the bearing near the base end portion of the second lubricant discharge pipe is also filled with the new lubricant, and the remaining deteriorated lubricant inside the bearing is sent to the second lubricant discharge pipe while being pressed by the new lubricant and discharged to the outside through the second discharge port (second lubricant supply and discharge process).

[0029] As described above, according to the lubricant replacement method in the bearing unit of the present invention, the supply and replacement of the lubricant into the bearing can be easily performed, whereby the bearing unit can be stably used over a long period while maximizing the life of the bearing itself in the bearing unit.

[0030] The invention according to claim 8 is a lubricant replacement method in the bearing unit according to claim 7, comprising a lubricant scraping step of scraping out the lubricant remaining in the first lubricant discharge pipe and the second lubricant discharge pipe from the first discharge port and the second discharge port in a state where the first discharge port and the second discharge port are open after the second lubricant supply ·Emission process, and a discharge port closing step of closing the first discharge port and the second discharge port.

[0031] According to this configuration, after the second lubricant supply ·EmissionAfter the process, any lubricant remaining in the first and second lubricant discharge pipes is scraped out through the first and second outlets (lubricant scraping process). Then, the first and second outlets are closed (outlet closing process). This allows the inside of the bearing to communicate with the outside through the first and second vents of the first and second lubricant discharge pipes, thereby suppressing the rise in internal pressure of the bearing and preventing lubricant leakage from the first and second bearing covers. Normally, the first and second outlets are closed, so even if lubricant reaches the first or second outlet during use of the bearing unit, leakage of that lubricant can be prevented. [Brief explanation of the drawing]

[0032] [Figure 1] The image shows a bearing unit according to one embodiment of the present invention, where (a) is a left side view and an enlarged view of the tip of the left grease discharge pipe, (b) is a longitudinal cross-sectional view, and (c) is a right side view and an enlarged view of the tip of the right grease discharge pipe. [Figure 2] This figure shows an enlarged view of the longitudinal cross-sectional view of the bearing unit shown in Figure 1(b). [Figure 3] This diagram illustrates the first grease supply and discharge process during grease replacement in a bearing unit, with (a) and (b) corresponding to Figures 1(a) and (c), respectively. [Figure 4] These diagrams illustrate the flow of grease in the first grease supply and discharge process, with (a) and (b) corresponding to Figures 1(a) and (c), respectively. [Figure 5] This diagram illustrates the flow of grease during grease replacement in a bearing unit, and corresponds to Figure 1(b). [Figure 6] This diagram illustrates the second grease supply and discharge process during grease replacement in a bearing unit, with (a) and (b) corresponding to Figures 1(a) and (c), respectively. [Figure 7]These diagrams illustrate the flow of grease in the second grease supply and discharge process, with (a) and (b) corresponding to Figures 1(a) and (c), respectively. [Figure 8] This diagram schematically shows a three-way valve for opening and closing both vents. [Figure 9] This diagram illustrates the open and closed states of both vents. (a) shows both vents open to the atmosphere, (b) shows the left vent open to the atmosphere and the right vent closed, and (c) shows the right vent open to the atmosphere and the left vent closed. [Modes for carrying out the invention]

[0033] Preferred embodiments of the present invention will be described in detail below with reference to the drawings. Figure 1 shows a bearing unit according to one embodiment of the present invention, where (a) is a left side view, (b) is a longitudinal cross-sectional view, and (c) is a right side view. Figure 2 shows an enlarged longitudinal cross-sectional view of the bearing unit shown in Figure 1(b). This bearing unit 1 is applied to elevator hoisting machines and the like, and rotatably supports the shaft of the hoisting machine.

[0034] As shown in Figures 1 and 2, the bearing unit 1 comprises a pedestal 2 (housing) having a predetermined shape, a bearing 4 that is held within the pedestal 2 and rotatably supports a horizontally extending shaft 3, and an outer cover 5 (first or second bearing cover) and an inner cover 6 (second or first bearing cover) attached to the pedestal 2 so as to cover both sides of the bearing 4 with the shaft 3 passing through it. Although not shown in the illustration, a sheave for a hoisting machine that rotates integrally with the shaft 3 is provided on the right side of the bearing unit 1 shown in Figures 1(b) and 2, while a motor that rotates the shaft 3 is provided on the left side.

[0035] The pedestal 2 is formed by casting or the like, and has a horizontally elongated rectangular shape in plan view. It consists of a plate-shaped base portion 7 with a predetermined thickness and a bearing holder portion 8 integrally provided on the upper side of the base portion 7 to hold the bearing 4. The base portion 7 has a plurality of mounting holes (not shown) that penetrate in the vertical direction, and the bearing unit 1 is fixed by inserting bolts through these mounting holes. On the other hand, the bearing holder portion 8 has a bearing housing portion 9 into which the bearing 4 is fitted. This bearing housing portion 9 penetrates horizontally and has approximately the same diameter as the outer diameter of the outer ring 11 of the bearing 4, which will be described later.

[0036] Furthermore, the upper part of the bearing holder portion 8 is provided with a grease supply passage 10 (lubricant supply passage) that extends vertically through it and supplies grease as a lubricant to the bearing 4. This grease supply passage 10 has a relatively small predetermined diameter and is located approximately in the center of the thickness direction (left-right direction in Figure 2) of the bearing holder portion 8.

[0037] The bearing 4 consists of an outer ring 11, an inner ring 12, a plurality of rollers 13 (rolling elements), and a cage (not shown). More specifically, the outer ring 11 has an outer diameter that is approximately the same as the diameter of the bearing housing 9 of the pedestal 2, and its outer circumferential surface is in close contact with the circumferential surface of the bearing housing 9. In addition, a ring groove 11a is formed on the outer circumferential surface of the outer ring 11, opening outward in the center in its width direction (left-right direction in Figure 2) and extending along the entire circumferential direction of the outer ring 11. Furthermore, a plurality of grease introduction holes 11b (lubricant introduction holes) are formed in this ring groove 11a so as to penetrate each other at predetermined intervals along the circumferential direction, for introducing grease to the inner circumferential surface side of the outer ring 11.

[0038] The inner ring 12 has an outer diameter smaller than the inner diameter of the outer ring 11, and an inner diameter that is approximately the same as the outer diameter of a predetermined portion 3a of the shaft 3 to which the inner ring 12 is fixed.

[0039] Each roller 13 is formed in a barrel shape. Between the inner circumferential surface of the outer ring 11 and the outer circumferential surface of the inner ring 12, two sets of roller rows 13A and 13B (rolling element rows), each consisting of multiple rollers 13 arranged at predetermined intervals along their circumferential directions, are arranged in parallel in the width direction (left-right direction in Figure 2) of the bearing 4. Therefore, this bearing 4 is composed of a so-called self-aligning roller bearing.

[0040] Both the outer cover 5 and the inner cover 6 are made of a metal plate or the like, have a donut-shaped planar form, and are formed three-dimensionally in the thickness direction (left-right direction in Figure 2). The outer cover 5 is located on the left side of the bearing unit 1, i.e., on the motor side (not shown), and is fixed to the left side surface of the bearing holder portion 8 by a number of bolts 14 (eight in Figure 1(a)) arranged along the outer circumference of the outer cover 5.

[0041] Furthermore, the outer cover 5 is positioned on the left side of the bearing unit 1 with a ring-shaped oil seal 15 having a predetermined diameter interposed between it and the left side surface of the inner ring 12, and a ring-shaped oil packing 16 having a larger diameter than the oil seal 15 interposed between it and the left side surface of the bearing holder portion 8. The oil seal 15 is installed so as to slide against the left side surface of the inner ring 12 and the outer circumferential surface of the shaft 3, while the oil packing 16 is installed so as to press against the left side surface of the bearing holder portion 8. The outer cover 5, oil seal 15 and oil packing 16 maintain a liquid-tight state in the space LS on the left side of the bearing 4 (hereinafter referred to as the "left space").

[0042] Furthermore, the base end of a grease discharge pipe 17 (first or second lubricant discharge pipe) is connected to the lower part of the outer cover 5, extending a predetermined length in the front-to-back direction (left-to-right direction in Figure 1(a)) when horizontal. The grease discharge pipe 17 has a rectangular prism shape on its exterior, and inside, a discharge passage 17a is formed along its entire length, with a circular cross-section for discharging deteriorated grease from within the bearing 4, and an outlet 17b (first or second outlet) is provided at its tip. In addition, a ventilation hole 17c (first or second ventilation hole) is formed at the tip of the grease discharge pipe 17, connecting the discharge passage 17a to the outside and opening upward.

[0043] On the other hand, the inner cover 6 is configured to be almost symmetrical to the outer cover 5 described above. Specifically, the inner cover 6 is located on the right side of the bearing unit 1, i.e., on the sheave side (not shown), and is fixed to the right side of the bearing holder portion 8 by a number of bolts 24 (eight in Figure 1(c)) arranged along the outer circumference of the inner cover 6.

[0044] Furthermore, the inner cover 6 is positioned on the right side of the bearing unit 1 via an oil seal 25 and an oil packing 26, which are configured in substantially the same manner as the oil seal 15 and oil packing 16 described above. The inner cover 6, oil seal 25, and oil packing 26 maintain a liquid-tight state in the space RS on the right side of the bearing 4 (hereinafter referred to as the "right space").

[0045] Furthermore, a grease discharge pipe 27 (second or first lubricant discharge pipe) is provided at the lower part of the inner cover 6, configured similarly to the grease discharge pipe 17 connected to the outer cover 5. That is, this grease discharge pipe 27 extends a predetermined length in the front-to-back direction (left-to-right direction in Figure 1(c)) when horizontal, and its base end is connected to the lower part of the inner cover 6. In addition, this grease discharge pipe 27 is provided with a discharge passage 27a and an outlet 27b (second or first outlet) similar to the grease discharge pipe 17 described above, and a vent hole 27c (second or first outlet) that opens upward is formed at its tip.

[0046] In the following explanation, the grease discharge pipe 17 connected to the outer cover 5 and located on the left side of the bearing unit 1 will be referred to as the "left grease discharge pipe 17" as appropriate, and the grease discharge pipe 27 connected to the inner cover 6 and located on the right side of the bearing unit 1 will be referred to as the "right grease discharge pipe 27" as appropriate.

[0047] The bearing unit 1, configured as described above, is used with grease filled into the bearing 4, specifically with grease present between the outer ring 11 and the inner ring 12 and around each roller 13. During normal use of the bearing unit 1, both outlets 17b and 27b of the left and right grease discharge pipes 17 and 27 are closed by plugs 18 and 28, which will be described later, while both vent holes 17c and 27c are kept open. Closing both outlets 17b and 27b prevents grease leakage from both outlets 17b and 27b when the bearing unit 1 is in use, and opening both vent holes 17c and 27c suppresses an increase in the internal pressure of the bearing 4.

[0048] Next, the method for replacing the grease in the bearing unit 1 will be explained with reference to Figures 3 to 7. This grease replacement is performed, for example, at predetermined intervals to maintain the smooth rotational support of the shaft 3 by the bearing unit 1. The bearing unit 1 is pre-filled with grease, and in the following explanation, when distinguishing between the grease to be replaced and the newly supplied grease in the bearing unit 1, the former will be referred to as "degraded grease" and the latter as "new grease."

[0049] Figure 3 shows the state immediately before new grease is supplied to the bearing unit 1, where (a) is a left side view and an enlarged view of the tip of the left grease discharge pipe 17, and (b) is a right side view and an enlarged view of the tip of the right grease discharge pipe 27. As shown in the figure, a grease nipple 30 is attached to the upper end of the bearing unit 1, specifically the upper end of the grease supply passage 10 of the pedestal 2. This grease nipple 30 has a check valve and is configured to allow new grease to be injected into the grease supply passage 10 from the outside and to prevent backflow of the injected new grease. This grease nipple 30 may be permanently attached to the grease supply passage 10.

[0050] Furthermore, as shown in the enlarged view of Figure 3(a), the left grease discharge pipe 17 is held in an open state, with its outlet 17b and vent hole 17c open. On the other hand, as shown in the enlarged view of Figure 3(b), the right grease discharge pipe 27 is held in a closed state, with its outlet 27b and vent hole 27c closed by plugs 28 and 29, respectively. These plugs 28 and 29 are configured to be screwed into the outlet 27b and vent hole 27c in an airtight manner, and can be easily removed by turning them in the opposite direction to the screwing direction.

[0051] In the state described above for bearing unit 1, first, a grease supply device such as a grease gun filled with new grease is connected to the grease nipple 30, and the new grease is injected under pressure into the grease supply passage 10 of the pedestal 2. In this case, the new grease is injected under pressure while rotating the shaft 3. This raises the temperature of bearing 4, which reduces the viscosity of the grease inside bearing 4 and increases its fluidity.

[0052] Figures 4 and 5 show the flow of grease during grease replacement in the bearing unit 1 using arrows. As shown in both figures, the new grease, which is press-injected into the grease supply passage 10 of the pedestal 2 via the grease nipple 30, reaches the ring groove 11a on the outer circumference of the outer ring 11 of the bearing 4 and flows downward along the ring groove 11a. In this case, the new grease that reaches the ring groove 11a is introduced through a plurality of grease introduction holes 11b to the inner circumference side of the outer ring 11, that is, between the outer ring 11 and the inner ring 12, and between the two roller rows 13A and 13B. The new grease introduced between the two roller rows 13A and 13B then flows to both sides of the bearing 4, that is, the left space LS and the right space RS, while pressing against the deteriorated grease.

[0053] Furthermore, the new grease that flows into the left space LS further compresses the deteriorated grease as it flows into the discharge passage 17a of the left grease discharge pipe 17. The deteriorated grease that flows into the discharge passage 17a of the left grease discharge pipe 17 is then discharged to the outside through the outlet 17b. In this case, as shown in Figure 4(b), since both the outlet 27b and the vent hole 27c of the right grease discharge pipe 27 are closed in an airtight state, the internal pressure becomes high in the discharge passage 27a of the right grease discharge pipe 27 and in the right space RS near the base end of the right grease discharge pipe 27, and the flow of grease is suppressed.

[0054] Then, when the deteriorated grease flowing out from the outlet 17b of the left grease discharge pipe 17 is replaced with new grease, it is assumed that all of the deteriorated grease to be discharged from the left grease discharge pipe 17 has been discharged, and the supply of new grease is temporarily stopped. The above process of supplying new grease and discharging deteriorated grease (Figures 3 to 5) is the first grease supply and discharge process, which corresponds to the first lubricant supply and discharge process of the present invention.

[0055] Next, as shown in Figure 6(a), the outlet 17b and vent hole 17c of the left grease discharge pipe 17 are closed by plugs 18 and 19, respectively, which are configured in the same way as the plugs 28 and 29 described above. On the other hand, for the right grease discharge pipe 27, plugs 28 and 29 are removed, and the outlet 27b and vent hole 27c are opened as shown in Figure 6(b). Then, in this state, the supply of new grease is resumed.

[0056] Figure 7 is similar to Figure 4 described above and shows the flow of grease in the bearing unit 1 after the supply of new grease has been resumed. As shown in Figure 7(b), after the supply of new grease has been resumed, the outlet 27b and vent hole 27c of the right grease discharge pipe 27 are open, so the new grease that has flowed into the right space RS flows into the discharge passage 27a of the right grease discharge pipe 27, pushing against the deteriorated grease. The deteriorated grease that has flowed into the discharge passage 27a of the right grease discharge pipe 27 is then discharged to the outside through the outlet 27b. In this case, the outlet 17b and vent hole 17c of the left grease discharge pipe 17 are closed, and the discharge passage 17a is full of new grease, so the new grease in the discharge passage 17a does not flow.

[0057] Then, when the deteriorated grease flowing out from the outlet 27b of the right grease discharge pipe 27 is replaced with new grease, the deteriorated grease in the bearing unit 1 is considered to have been replaced with new grease, and the supply of new grease is stopped. The above steps of supplying new grease and discharging deteriorated grease (Figures 6 and 7) are the second grease supply and discharge step, which corresponds to the second lubricant supply and discharge step of the present invention.

[0058] As described above, immediately after replacing the grease in the bearing unit 1, the discharge passages 17a and 27a of the left and right grease discharge pipes 17 and 27 are filled with new grease. Therefore, in order to allow the inside of the bearing unit 1 to communicate with the outside through both vent holes 17c and 27c when the bearing unit 1 is used thereafter, the new grease in both discharge passages 17a and 27a is scraped out using a predetermined tool (lubricant scraping step). After the new grease has been scraped out from the left and right grease discharge pipes 17 and 27, both discharge ports 17b and 27b are closed by plugs 18 and 28 (discharge port closing step). With this, the grease replacement in the bearing unit 1 is completed.

[0059] In the bearing unit 1 described above, the vent holes 17c and 27c of the left and right grease discharge pipes 17 and 27 are opened and closed by attaching and detaching plugs 19 and 29 to the vent holes 17c and 27c, respectively. However, the opening and closing operation may also be performed using a three-way valve 40 as shown below.

[0060] Figure 8 schematically shows a three-way valve 40 (ventilation hole opening / closing device) for opening and closing the ventilation holes 17c and 27c of the left and right grease discharge pipes 17 and 27. The three-way valve 40 is connected to the left grease discharge pipe 17 via a left connector 41 and left piping 41a, which are located in the ventilation hole 17c of the left grease discharge pipe 17. The three-way valve 40 is also connected to the right grease discharge pipe 27 via a right connector 42 and right piping 42a, which are located in the ventilation hole 27c of the right grease discharge pipe 27. Furthermore, the three-way valve 40 is open to the atmosphere via piping 40a.

[0061] As described above, the three-way valve 40 connected to both vents 17c and 27c opens and closes in the three patterns shown in Figures 9(a) to (c). In the same figure, ventilation by the three-way valve 40 is indicated by a white arrow.

[0062] In the first pattern shown in Figure 9(a), both vents 17c and 27c are open to the atmosphere. In the second pattern shown in Figure 9(b), the vent 17c of the left grease discharge pipe 17 is open to the atmosphere, while the vent 27c of the right grease discharge pipe 27 is closed. Furthermore, in the third pattern shown in Figure 9(c), the vent 17c of the left grease discharge pipe 17 is closed, while the vent 27c of the right grease discharge pipe 27 is open to the atmosphere.

[0063] With the three-way valve 40 configured as described above, the three-way valve 40 is set to the first pattern during normal use of the bearing unit 1. On the other hand, when changing the grease, the three-way valve 40 is set to the second pattern to execute the first grease supply and discharge process described above, and then the three-way valve 40 is set to the third pattern to execute the second grease supply and discharge process described above. In this way, by simply operating the three-way valve 40, both vent holes 17c and 27c of the left and right grease discharge pipes 17 and 27 can be opened and closed, making it easy to switch between the open and closed states of both vent holes 17c and 27c during normal use of the bearing unit 1 and when changing the grease.

[0064] As described in detail above, according to this embodiment, even if the internal pressure of the bearing 4 increases due to the temperature rise caused by use in the grease-filled bearing unit 1, the inside of the bearing 4 is open to the atmosphere through two ventilation holes 17c and 27c provided in the left and right grease discharge pipes 17 and 27, respectively. Therefore, the rise in internal pressure of the bearing 4 is suppressed, and smooth rotation of the inner ring 12 relative to the outer ring 11 is ensured while preventing grease leakage from the outer cover 5 and inner cover 6.

[0065] Furthermore, when replacing the grease in the bearing unit 1, the outlet 17b(27b) and vent hole 17c(27c) of one of the left and right grease discharge pipes 17 and 27 are closed, while the outlet 27b(17b) and vent hole 27c(17c) of the other are left open, and new grease is injected into the bearing unit 1. This allows the deteriorated grease inside the bearing unit 1 to be pressed by the new grease and discharged to the outside through the outlet 27b(17b), while the new grease is filled into the bearing unit 1. In this way, the supply and replacement of grease inside the bearing unit 1 can be easily performed, thereby ensuring the maximum lifespan of the bearing 4 itself in the bearing unit 1 and allowing for stable use over a long period of time.

[0066] It should be noted that the present invention is not limited to the embodiments described above and can be implemented in various forms. For example, although the embodiment described the case in which the bearing unit 1 of the present invention is applied to a hoisting machine, the present invention is not limited thereto and can be applied to various equipment. Furthermore, although the embodiment used a self-aligning roller bearing having two sets of roller rows 13A and 13B as the bearing 4 in the bearing unit 1, the present invention is not limited thereto and can also use a bearing having three or more sets of roller rows, or a double-row ball bearing using balls as rolling elements and having two or more sets of ball rows. Moreover, it is also possible to configure the bearing 4 by combining two bearings having one set of rolling element rows each.

[0067] In this embodiment, a ring groove 11a is formed on the outer circumferential surface of the outer ring 11 of the bearing 4, and the grease supply passage 10 of the pedestal 2 and the grease introduction hole 11b of the outer ring 11 are connected via this ring groove 11a. However, it is also possible to form a similar ring groove on the entire circumferential surface of the bearing housing portion 9 of the pedestal 2, either in place of or together with the ring groove 11a.

[0068] Furthermore, although the embodiment described a method for replacing grease in a bearing unit 1 that is already filled with grease, it is also possible to fill the grease during the initial filling in the same manner as the grease replacement method described above.

[0069] Furthermore, although grease was used as the lubricant in the embodiment of the present invention, the present invention is not limited thereto, and various other lubricants suitable for the bearing 4 can be used.

[0070] Furthermore, the detailed configurations of the bearing unit 1, bearing 4, outer cover 5, inner cover 6, and grease discharge pipes 17 and 27 shown in the embodiment are merely illustrative examples and can be modified as appropriate within the scope of the present invention. [Explanation of Symbols]

[0071] 1 Bearing Unit 2 Pedestals (Housing) 3 shafts 4 bearings 5. Outer cover (first or second bearing cover) 6. Inner small cover (second or first bearing cover) 7 Base section 8. Bearing holder section 9. Bearing housing 10. Grease supply passage (lubricant supply passage) 11 Outer ring 11a Ring groove 11b Grease introduction hole (lubricant introduction hole) 12 Inner Ring 13 Rolling element 13A Roller row (rolling element row) 13B Roller row (rolling element row) 17. Grease discharge pipe (first or second lubricant discharge pipe) 17a Discharge passage 17b Discharge port (1st or 2nd discharge port) 17c Ventilation holes (first or second ventilation holes) 27. Grease discharge pipe (second or first lubricant discharge pipe) 27a Discharge passage 27b Discharge port (2nd or 1st discharge port) 27c Ventilation holes (second or first ventilation holes) 30 Grease Nipples 40. Three-way valve (vent opening / closing device) LS left space RS Right Space

Claims

1. A bearing unit comprising a housing having a bearing housing portion that penetrates in a predetermined direction, and a bearing housed in the bearing housing portion and rotatably supporting a shaft extending along the predetermined direction, The bearing comprises an outer ring whose outer surface is in close contact with the circumferential surface of the bearing housing, an inner ring positioned inside the outer ring and fixed to the shaft with the shaft passing through it, and multiple sets of rolling element rows, each consisting of multiple rolling elements arranged circumferentially between the outer ring and the inner ring. A ring-shaped groove is formed on at least one of the circumferential surface of the bearing housing and the circumferential surface of the outer ring, opening toward the other and extending along the circumferential direction and formed over the entire circumferential direction. The housing has a lubricant supply passage that connects the outside to the ring groove and supplies lubricant to the bearing from the outside. The outer ring has a plurality of lubricant introduction holes that connect the ring groove and the inner circumferential surface of the outer ring, are arranged at predetermined intervals from each other along the circumferential direction of the outer ring, and introduce lubricant supplied to the ring groove to the inner circumferential surface of the outer ring. The shaft passes through the housing and covers the bearing housing from both sides, respectively, and is attached to the housing, with first and second bearing covers for preventing leakage of lubricant, A first lubricant discharge pipe is provided so as to extend outward for a predetermined length from a predetermined portion of the first bearing cover, and is used to discharge the lubricant inside the bearing to the outside from a first discharge port at its tip, A second lubricant discharge pipe is provided so as to extend outward for a predetermined length from a predetermined portion of the second bearing cover, and is used to discharge the lubricant inside the bearing to the outside from a second discharge port at its tip, Furthermore, The tip of the first lubricant discharge pipe is provided with a first vent hole that can be opened and closed, which connects the inside and outside of the first lubricant discharge pipe. A bearing unit characterized in that the tip of the second lubricant discharge pipe is provided with a second vent hole that can be opened and closed, which connects the inside and outside of the second lubricant discharge pipe.

2. The bearing unit according to claim 1, characterized in that the multiple sets of rolling element rows are composed of two sets of rolling element rows.

3. The bearing unit according to claim 2, characterized in that each of the plurality of lubricant introduction holes is provided so as to be located between the two sets of rolling element rows.

4. The bearing unit according to claim 3, characterized in that the lubricant supply passage is provided in the upper part of the housing so as to extend in the vertical direction.

5. The first lubricant discharge pipe is configured such that its base end is provided at the lower part of the first bearing cover and it extends perpendicularly and horizontally with respect to the shaft. The bearing unit according to claim 4, characterized in that the second lubricant discharge pipe has its base end provided at the lower part of the second bearing cover and is configured to extend perpendicularly and horizontally with respect to the shaft.

6. The bearing unit according to claim 1, further comprising a vent opening / closing device connected to the first vent and the second vent, configured to normally open the first vent and the second vent to the atmosphere, and configured to close one of the first vent and the second vent and open the other of the first vent and the second vent to the atmosphere when a lubricant is supplied.

7. A method for replacing the lubricant in a bearing unit according to any one of claims 1 to 6, A first lubricant supply and discharge step is performed in which, with the first discharge port and first vent hole of the first lubricant discharge pipe open and the second discharge port and second vent hole of the second lubricant discharge pipe closed, new lubricant is supplied to the bearing via the lubricant supply passage and deteriorated lubricant is discharged from the first discharge port, After the discharge of the deteriorated lubricant from the first discharge port is completed, the second lubricant supply and discharge step is performed in which the second discharge port and second vent hole of the second lubricant discharge pipe are opened, and the first discharge port and first vent hole of the first lubricant discharge pipe are closed, and new lubricant is supplied to the bearing through the lubricant supply passage, and deteriorated lubricant is discharged from the second discharge port. A method for replacing the lubricant in a bearing unit, characterized by having the following features.

8. After the second lubricant supply and discharge step, with the first and second discharge ports open, a lubricant scraping step is performed in which the lubricant remaining in the first and second lubricant discharge pipes is scraped out to the outside through the first and second discharge ports. A discharge port closing step of closing the first discharge port and the second discharge port, A method for replacing the lubricant in a bearing unit according to claim 7, further comprising the features described above.

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