Grease supply structure of bearing

Abstract

This grease supply structure for a bearing is provided with: a hollow housing; an outer bearing, the outer ring of which is held on the inner circumferential surface of the housing; a hollow first rotating body fixed to the inner ring of the outer bearing; an inner bearing, the outer ring of which is held on the inner circumferential surface of the first rotating body; and a second rotating body fixed to an inner ring of the inner bearing, the housing having a first grease supply path through which a lubricant supplied to the inner bearing flows, the downstream side of the first grease supply path communicating with a sealed first sealed space between the housing and the first rotating body, and the downstream side of the first grease supply path communicating with a second sealed space between the housing and the second rotating body. The first rotating body has a second grease supply path whose upstream side communicates with the first sealed space, the downstream side of the second grease supply path communicates with a sealed second sealed space between the first rotating body and the second rotating body, and the inner bearing is disposed in the second sealed space.

Description

Technical Field

[0001] The present invention relates to a grease supply structure for supplying lubricant to a bearing. Background Art

[0002] Patent Document 1 below discloses an injection molding machine that can move an injection screw by converting the rotational motion of a ball screw into linear motion using a combination of a ball screw and a ball nut to press a push plate. The injection molding machine has the following structure.

[0003] The screw sleeve provided with the injection screw is provided in the through hole of the push plate via a bearing. Therefore, the screw sleeve can rotate relative to the push plate. The ball screw is provided in the inner peripheral portion of the screw sleeve via a bearing. Therefore, the ball screw can rotate relative to the screw sleeve. In an injection molding machine with such a structure, the injection screw rotates during metering and kneading, and the ball screw rotates during injection. Therefore, during molding, the inner and outer rings of the bearings between the ball screw and the screw sleeve rotate.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 8-192447 Summary of the invention

[0007] Problem that the invention aims to solve

[0008] In recent years, the bearings between the ball screw and the screw sleeve are often used under severe conditions. Therefore, in order to improve durability, it is necessary to regularly grease (supply lubricant) the bearings between the ball screw and the screw sleeve.

[0009] In the case of a structure in which the inner ring and the outer ring rotate as described above, if grease is supplied to the bearing between the ball screw and the screw sleeve from the automatic grease supply device via the tube, the tube rotates, so automatic grease supply using the tube cannot be performed. Therefore, it is conceivable to manually supply grease using a grease gun while the injection molding machine is stopped.

[0010] However, in this case, the injection molding machine needs to be stopped, which leads to a decrease in the utilization rate of the injection molding machine. In addition, since grease is supplied manually, problems such as forgetting to supply grease or difficulty in grease supplying may occur. Therefore, a grease supply structure that can easily supply grease to the inner ring and outer ring rotating bearings with a simple structure is desired.

[0011] Solutions for solving problems

[0012] The cam is an assembly of a plurality of bearings, each of which has a first grease supply path and a second grease supply path connected to the inner ring of the outer bearing and a second grease supply path connected to the inner ring of the first bearing and a second grease supply path connected to the inner ring of the first bearing and a second grease supply path connected to the inner ring of the first bearing and a second grease supply path connected to the inner ring of the first bearing and a second grease supply path connected to the inner ring of the first bearing and a second grease supply path connected to the inner ring of the first bearing and a second grease supply path connected to the inner ring of the first bearing and a second grease supply path connected to the inner ring of the first bearing and a second grease supply path connected to the inner ring of the first bearing and a second grease supply path connected to the inner ring of the first bearing and a second grease supply path connected to the inner ring of the first bearing and a second grease supply path connected to the inner ring of the first bearing and a second grease supply path connected to the inner ring of the first bearing and a second grease supply path connected to the inner ring of the first bearing and a second grease supply path connected to the inner ring of the first bearing and a second grease supply path connected to the inner ring of the first bearing and a second grease supply path connected to the inner ring of the first bearing and a second grease supply path connected to the inner ring of the first bearing and a second grease supply path connected to the inner ring of the first bearing and a second grease supply path connected to the inner ring of the first bearing and a second grease supply path

[0013] Effects of the Invention

[0014] According to one aspect, it is possible to provide a grease supply structure that can easily supply grease to a rotatable inner ring and an outer ring of a bearing with a simple structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a right side view showing an example of an injection molding machine to which the grease supply structure for a bearing according to the first embodiment of the present invention is applied, and a part of the structure is shown in cross section.

[0016] Figure 2 It is a right side view showing a modified example of the grease supply structure of the bearing according to the first embodiment, and a part of the structure is shown in cross section.

[0017] Figure 3 It is a right side view showing a grease supply structure of a bearing according to a second embodiment of the present invention, and shows a part in cross section.

[0018] Figure 4 It is a right side view showing a modified example of the grease supply structure of the bearing according to the second embodiment, and a part of the structure is shown in cross section.

[0019] Figure 5 This is a right side view showing a grease supply structure of a bearing according to a third embodiment of the present invention, and a part of the structure is shown in cross section.

[0020] Figure 6 It is a right side view showing a modified example of the grease supply structure of the bearing according to the third embodiment, and a part is shown in cross-section. DETAILED DESCRIPTION

[0021] Hereinafter, a grease supply structure of a bearing according to one embodiment of the present disclosure will be described with reference to the accompanying drawings. Figure 1, the grease supply structure of the bearing of the first embodiment is described. The grease supply structure of the bearing includes a housing 1, an outer bearing 2, a first rotating body 3, an inner bearing 4, and a second rotating body 5. Here, the case where the present invention is applied to an injection molding machine 6 is described. It should be noted that the device to which the present invention is applied is not limited to the injection molding machine 6.

[0022] The injection molding machine 6 includes a front plate 7 and a rear plate 8 disposed face to face, a guide rod 9 connecting the front plate 7 and the rear plate 8, a housing 1 slidably provided on the guide rod 9, a first rotating body 3 rotatably provided on the housing 1 and immovably provided in the axial direction, an injection screw 10 provided on the first rotating body 3, a second rotating body 5 rotatably provided on the first rotating body 3 and immovably provided in the axial direction, and a ball nut 11 provided on the rear plate 8. The injection molding machine 6 can move the injection screw 10 by converting the rotational motion of the second rotating body 5 screwed into the ball nut 11 into a linear motion and pressing the housing 1.

[0023] The front plate 7 is plate-shaped. An injection cylinder 12 is provided on the front plate 7. The rear plate 8 is plate-shaped. The rear plate 8 has a through hole 13 that penetrates in the thickness direction. The front plate 7 and the rear plate 8 are connected by a plurality of rod-shaped guide rods 9. Specifically, by Figure 1 The rear plate 8 is fixed at the right end of the guide rod 9 and at the other axial end of the guide rod 9 ( Figure 1 The front plate 7 is fixed to the left end portion in the middle, and the front plate 7 and the rear plate 8 are connected in a face-to-face state.

[0024] The housing 1 is in the shape of a thick plate. The housing 1 has a plurality of insertion holes 14 that penetrate in the thickness direction (also in the axial direction of the guide rod 9). The housing 1 is set on the guide rod 9 by passing the guide rod 9 through the insertion holes 14. In a state where the guide rod 9 is passed through the insertion holes 14, a cylindrical bushing 15 is set between the inner peripheral surface of the insertion hole 14 and the outer peripheral surface of the guide rod 9. In this way, the housing 1 is set on the guide rod 9 in a manner that it can slide along the axial direction of the guide rod 9.

[0025] The housing 1 has a through hole 16 that penetrates in the thickness direction. The through hole 16 is located in the substantially central portion of the housing 1. In the example shown in the figure, the through hole 16 is a stepped hole. That is, the through hole 16 has a small diameter hole 17 located at one end side in the axial direction and a large diameter hole 18 located at the other end side in the axial direction. Since the through hole 16 is provided in the housing 1, in other words, the housing 1 is hollow with an inner peripheral surface.

[0026] The first rotating body 3 has a columnar main body 19 and a pressing portion 20 for pressing the inner bearing 4 described later. The main body 19 is a stepped cylindrical body having a plurality of axial ends ( Figure 1The main body 19 includes a large diameter portion 21 (on the right end side in the figure) and a small diameter portion 22 adjacent to the large diameter portion 21. The main body 19 has a recess 23 that is circular in a rear view on one axial end surface. The recess 23 is open on one axial end side of the main body 19. In the example shown in the figure, the recess 23 is stepped and has a large diameter hole portion 24 located on one axial end side and a small diameter hole portion 25 located on the other axial end side. Since the recess 23 is provided on the first rotating body 3, in other words, the first rotating body 3 is hollow with an inner circumferential surface. The injection screw 10 is fixed to the other axial end side of the main body 19 by bolts or the like. The pressing portion 20 is plate-shaped and has a through hole 26 that penetrates in the thickness direction. The first rotating body 3 is rotatably held in the housing 1 via the outer bearing 2. In the first embodiment, the outer bearing 2 is, for example, a ball bearing.

[0027] The outer bearing 2 has adjacent first bearing 27 and second bearing 28, an annular outer ring spacer 31 connecting the outer ring 29 of the first bearing 27 and the outer ring 30 of the second bearing 28, and an annular inner ring spacer 34 connecting the inner ring 32 of the first bearing 27 and the inner ring 33 of the second bearing 28. A cylindrical gap is formed between the outer ring spacer 31 and the inner ring spacer 34. The outer bearing 2 of such a structure is arranged in the housing 1 by being held on the inner peripheral surface of the large diameter hole 18 by the outer ring 29 of the first bearing 27 and the outer ring 30 of the second bearing 28. When the outer bearing 2 is arranged in the housing 1, the outer ring spacer 31 is located at one axial end side ( Figure 1 The outer ring 29 of the first bearing 27 (on the right end side in the figure) contacts the step portion between the large diameter hole 18 and the small diameter hole 17, and the outer ring 30 of the second bearing 28 located on the other axial end side of the outer bearing 2 contacts the pressing portion 36 provided on the housing 1. The pressing portion 36 is plate-shaped and is fixed to the other axial end surface of the housing 1 by bolts or the like. The pressing portion 36 has a through hole 37 that penetrates in the thickness direction. In this way, the outer ring (29, 30) of the outer bearing 2 is held on the inner circumferential surface of the hollow housing 1.

[0028] The main body 19 of the first rotating body 3 is held by the inner ring 32 of the first bearing 27 and the inner ring 33 of the second bearing 28. At this time, the outer peripheral surface of the small diameter portion 22 of the main body 19 is fixed to the inner ring 32 of the first bearing 27 and the inner ring 33 of the second bearing 28. In a state where the first rotating body 3 is held by the outer bearing 2, the inner ring 32 of the first bearing 27 contacts the step portion between the large diameter portion 21 and the small diameter portion 22, and the inner ring 33 of the second bearing 28 contacts the annular pressing portion 72 provided on the first rotating body 3. The pressing portion 72 is fixed to the first rotating body 3 in a state where the first rotating body 3 penetrates it. In this way, the first rotating body 3 is fixed to the inner ring (32, 33) of the outer bearing 2. In a state where the first rotating body 3 is fixed to the outer bearing 2, the other axial end portion ( Figure 1The left end portion in the middle) penetrates the opening on the other axial end side of the through hole 16 of the housing 1 and the through hole 37 of the pressing portion 36.

[0029] The second rotating body 5 is columnar. In the example shown in the figure, the other axial end side ( Figure 1 The inner bearing 4 is a ball bearing. In the first embodiment, a plurality of inner bearings 4 are used, but the inner bearing 4 may be one.

[0030] A plurality of inner bearings 4 are provided on the inner circumferential surface of the recess 23 of the first rotating body 3 in a state of contact with each other. At this time, the inner bearing 4 is provided on the first rotating body 3 by holding the outer ring 41 of the inner bearing 4 on the inner circumferential surface of the large diameter hole portion 24 of the recess 23. In the state where the plurality of inner bearings 4 are provided on the first rotating body 3, the outer ring 41 of the inner bearing 4 located on the inner side of the recess 23 contacts the step portion between the large diameter hole portion 24 and the small diameter hole portion 25, and the outer ring 41 of the inner bearing 4 located on the opening side of the recess 23 contacts the pressing portion 20 provided on the main body 19. The pressing portion 20 is fixed to one axial end surface of the main body 19 by bolts or the like. In this way, the outer ring 41 of the inner bearing 4 is held on the inner circumferential surface of the hollow first rotating body 3.

[0031] The small diameter portion 40 of the second rotating body 5 is held by the inner ring 43 of the inner bearing 4 in a state where the second rotating body 5 passes through the through hole 26 of the pressing portion 20 of the first rotating body 3. At this time, the outer peripheral surface of the small diameter portion 40 of the second rotating body 5 is fixed to the inner ring 43 of the inner bearing 4. In a state where the second rotating body 5 is held by the plurality of inner bearings 4, the inner ring 43 of the inner bearing 4 located on the opening side of the recess 23 contacts the step portion between the small diameter portion 40 and the large diameter portion 39, and the inner ring 43 of the inner bearing 4 located on the inner side of the recess 23 contacts the annular pressing portion 45 provided on the small diameter portion 40 of the second rotating body 5. The pressing portion 45 is fixed to the other axial end portion of the small diameter portion 40 in a state where the small diameter portion 40 is inserted therein. In this way, the second rotating body 5 is fixed to the inner ring of the inner bearing 4. It should be noted that in the first embodiment, the inner bearing 4 and the outer bearing 2 are double-arranged inside and outside.

[0032] The second rotating body 5 has an external thread on the outer peripheral surface except for the other axial end side. The second rotating body 5 is screwed into the ball nut 11 provided on the rear plate 8. The ball nut 11 is fixed to the through hole 13 of the rear plate 8 in a non-rotatable manner. The second rotating body 5 screwed into the ball nut 11 provided on the rear plate 8 passes through the through hole 13 of the rear plate 8. That is, one axial end portion of the second rotating body 5 protrudes from the through hole 13 of the rear plate 8. One axial end portion of the second rotating body 5 passes through the annular load sensor 46 provided on the rear plate 8. The load sensor 46 is fixed to the rear plate 8 by bolts or the like.

[0033] Next, the operation of the injection molding machine 6 will be described. In the injection molding machine 6, only the injection screw 10 rotates during metering and kneading, and only the second rotating body 5 rotates during injection. Therefore, the injection molding machine 6 has a motor 47 that rotates the first rotating body 3 to which the injection screw 10 is fixed, and a motor 48 that rotates the second rotating body 5. The motor 47 is provided in the housing 1. A driving pulley 49 is fixed to the driving shaft of the motor 47. A belt 51 is hung around the driving pulley 49 provided in the motor 47 and a driven pulley 50 provided at the other axial end of the first rotating body 3. The motor 48 is provided in the housing 1 in such a manner that the first rotating body 3 is located between the motor 47 and the motor 48. A driving pulley 52 is fixed to the driving shaft of the motor 48. A belt 54 is hung around the driving pulley 52 provided in the motor 48 and a driven pulley 53 provided in the second rotating body 5.

[0034] Due to such a structure, during metering and kneading, the injection screw 10 can be rotated by driving the motor 47 while the motor 48 is stopped. By rotating the injection screw 10, metering and kneading operations are performed, and molten resin is fed to the front end of the injection cylinder 12. During injection, the second rotating body 5 can be rotated by driving the motor 48 while the motor 47 is stopped. By rotating the second rotating body 5, the housing 1 can be moved toward the injection cylinder 12 side and the injection screw 10 can be moved in the injection cylinder 12 to perform injection.

[0035] The grease supply structure of the bearing of the first embodiment is applied to the above-mentioned injection molding machine 6. The grease supply structure of the bearing includes a hollow housing 1, an outer bearing 2 whose outer ring is held on the inner peripheral surface of the housing 1, a hollow first rotating body 3 fixed to the inner ring of the outer bearing 2, an inner bearing 4 whose outer ring is held on the inner peripheral surface of the first rotating body 3, and a second rotating body 5 fixed to the inner ring of the inner bearing 4. It should be noted that the housing 1, the outer bearing 2, the first rotating body 3, the inner bearing 4 and the second rotating body 5 have the above-mentioned structure.

[0036] like Figure 1As shown, the housing 1 has a first grease supply passage 55 for circulating lubricant supplied to the inner bearing 4. The opening on the upstream side of the first grease supply passage 55 opens to the outside of the housing 1. A grease supply port 56 composed of a grease nipple or the like is provided at the opening on the upstream side of the first grease supply passage 55. A grease supply device that automatically supplies lubricant is connected to the grease supply port 56. The downstream side of the first grease supply passage 55 is connected to a sealed first sealed space 57 between the housing 1 and the first rotating body 3. The opening portion of the cylindrical gap between the inner peripheral surface of the housing 1 and the outer peripheral surface of the first rotating body 3 is sealed by a sealing member, thereby forming the first sealed space 57.

[0037] The sealing member includes a first seal 58 provided on the outer side of the first bearing 27 and a second seal 59 provided on the outer side of the second bearing 28. The first seal 58 seals one axial end ( Figure 1 The second seal 59 seals the other axial end of the cylindrical gap between the outer ring spacer 31 and the inner ring spacer 34. The first sealed space 57 is formed by sealing the cylindrical gap between the outer ring spacer 31 and the inner ring spacer 34. In the case where the cylindrical gap sealed by the first seal 58 and the second seal 59 is the first sealed space 57, the downstream side of the first grease supply passage 55 is connected to the first sealed space 57 via the outer through hole 60 provided in the outer ring spacer 31.

[0038] like Figure 1 As shown, the first rotating body 3 has a second grease supply passage 61 for the lubricant flowing from the first grease supply passage 55 via the first sealed space 57. The upstream side of the second grease supply passage 61 is connected to the first sealed space 57. In the first embodiment, the cylindrical gap between the outer ring spacer 31 and the inner ring spacer 34 is the first sealed space 57. Therefore, the upstream side of the second grease supply passage 61 is connected to the first sealed space 57 via the inner through hole 62 provided in the inner ring spacer 34.

[0039] The downstream side of the second grease supply passage 61 is connected to the sealed second sealed space 63 between the first rotating body 3 and the second rotating body 5. The opening of the cylindrical gap between the inner peripheral surface of the first rotating body 3 and the outer peripheral surface of the second rotating body 5 is sealed by a sealing member 64, thereby forming the second sealed space 63. The sealing member 64 seals the gap between the inner peripheral surface of the first rotating body 3 and the outer peripheral surface of the second rotating body 5 on the opening side of the recess 23. The sealing member 64 is annular and is arranged between the inner peripheral surface of the pressing portion 20 of the first rotating body 3 and the outer peripheral surface of the large diameter portion 39 of the second rotating body 5. The sealing member 64 is set as a conventionally known oil seal, but is not limited thereto. The inner bearing 4 is arranged in the second sealed space 63 formed in this way.

[0040] like Figure 1 As shown, the first rotating body 3 penetrates the housing 1, so the first rotating body 3 has an exposed surface 65 exposed from the housing 1. Typically, the exposed surface 65 is the outer peripheral surface of the pressing portion 20 of the first rotating body 3. The first rotating body 3 has a discharge passage 66 for discharging the lubricant in the second sealed space 63 to the outside of the housing 1. The discharge passage 66 is, for example, provided at the pressing portion 20 of the first rotating body 3. The discharge passage 66 is a flow passage for discharging the lubricant that has passed through the inner bearing 4. Therefore, the upstream side of the discharge passage 66 is connected to the portion between the inner bearing 4 and the sealing member 64. The outlet of the discharge passage 66 opens at the exposed surface 65.

[0041] In the case of the grease supply structure of the first embodiment, the lubricant supplied from the grease supply device flows into the first sealed space 57 through the first grease supply passage 55. The lubricant flows from the first sealed space 57 through the second grease supply passage 61 into the second sealed space 63. Thus, the lubricant is supplied to the inner bearing 4. Thereafter, the lubricant is discharged to the outside of the housing 1 through the discharge passage 66. Therefore, according to the grease supply structure of the first embodiment, grease can be easily supplied to the inner bearing 4 rotating with the inner ring 43 and the outer ring 41 during the operation of the injection molding machine 6 with a simple structure, and in particular, it is also suitable for automation of grease supply.

[0042] In the case of the grease supply structure of the first embodiment, the outlet of the discharge passage 66 opens at the exposed surface 65. Therefore, according to the grease supply structure of the first embodiment, a simple structure can be formed compared with a structure in which the lubricant is discharged through the housing 1.

[0043] Next, use Figure 2 A modification of the grease supply structure of the bearing of the first embodiment will be described. It should be noted that, for components having the same reference numerals as those in the first embodiment, their functions are the same, so their description is sometimes omitted below. The grease supply structure of this modification has a plurality of first grease supply passages 55 and a plurality of second grease supply passages 61.

[0044] like Figure 2 As shown, the grease supply structure of this modified example has two first grease supply passages 55, 55 and second grease supply passages 61, 61 corresponding to the two first grease supply passages 55, 55, respectively. The two first grease supply passages 55, 55 are provided at positions opposite to each other across the first rotating body 3. The two second grease supply passages 61, 61 are provided at positions opposite to each other across the first rotating body 3. Accordingly, two outer through holes 60, 60 are provided in the outer ring spacer 31, and two inner through holes 62, 62 are provided in the inner ring spacer 34.

[0045] In the case of the grease supply structure of this modification, the lubricant is supplied from the two supply paths to the second sealed space 63. Therefore, according to the grease supply structure of this modification, the lubricant can be efficiently supplied to the second sealed space 63.

[0046] Next, use Figure 3 The grease supply structure of the bearing of the second embodiment of the present invention is described. It should be noted that, for the components having the same reference numerals as those in the first embodiment, their functions are the same, so their description is sometimes omitted below. In the grease supply structure of the second embodiment, the structure of the first sealed space 57 is different from that of the first embodiment.

[0047] like Figure 3 As shown, the through hole 16 of the housing 1 is a stepped hole having a small diameter hole 67 located at one axial end of the through hole 16 and a large diameter hole 69 located at the other axial end of the through hole 16 .

[0048] A plurality of outer bearings 2 are arranged in the large diameter hole 69 of the through hole 16 in a state of contact with each other. At this time, the outer bearing 2 is arranged in the housing 1 by holding the outer ring 79 of the outer bearing 2 on the inner peripheral surface of the large diameter hole 69. In the state where the plurality of outer bearings 2 are arranged in the housing 1, the outer ring 79 of the outer bearing 2 located at one axial end side of the through hole 16 contacts the step portion between the large diameter hole 69 and the small diameter hole 67, and the outer ring 79 of the outer bearing 2 located at the other axial end side of the through hole 16 contacts the pressing portion 36 provided in the housing 1. The pressing portion 36 is in the shape of a thick plate and is fixed to the other axial end surface of the housing 1 by bolts or the like. The pressing portion 36 has a through hole 37 that penetrates in the thickness direction. The through hole 37 is a stepped hole.

[0049] The main body 19 of the first rotating body 3 is held by the inner ring 80 of the outer bearing 2. At this time, the outer peripheral surface of the small diameter portion 22 of the main body 19 is fixed to the inner ring 80 of the outer bearing 2. In a state where the first rotating body 3 is held by the outer bearing 2, the inner ring 80 of the outer bearing 2 located at one axial end side of the through hole 16 contacts the step portion between the large diameter portion 21 and the small diameter portion 22, and the inner ring 80 of the outer bearing 2 located at the other axial end side of the through hole 16 contacts the annular pressing portion 72 provided on the first rotating body 3.

[0050] The opening of the cylindrical gap between the housing 1 and the first rotating body 3 at one axial end is sealed by the annular third seal 74, and the opening of the cylindrical gap between the housing 1 and the first rotating body 3 at the other axial end is sealed by the annular fourth seal 75, thereby forming the first sealed space 57. In the second embodiment, the fourth seal 75 seals the gap between the inner peripheral surface of the small diameter hole of the through hole 37 of the pressing portion 36 and the outer peripheral surface of the first rotating body 3. Due to such a structure, the outer bearing 2 is arranged in the first sealed space 57. At this time, a gap is formed between the outer bearing 2 located at one axial end side of the through hole 16 and the third seal 74, and between the outer bearing 2 located at the other axial end side of the through hole 16 and the fourth seal 75.

[0051] In this way, the outer bearing 2 is arranged in the first sealed space 57 in a manner that leaves the first portion 76 on the axial one end side of the first sealed space 57 and the second portion 77 on the axial other end side of the first sealed space 57. In this case, the downstream side of the first grease supply passage 55 is connected to the first portion 76. The upstream side of the second grease supply passage 61 is connected to the second portion 77.

[0052] In the case of the grease supply structure of the second embodiment, the lubricant supplied from the grease supply device flows into the first portion 76 of the first sealed space 57 through the first grease supply passage 55. The lubricant flows from the first portion 76 of the first sealed space 57 through the inside of the outer bearing 2 to the second portion 77. The lubricant flows from the second portion 77 of the first sealed space 57 through the second grease supply passage 61 to the second sealed space 63. Thus, the lubricant is supplied to the inner bearing 4. Thereafter, the lubricant is discharged to the outside of the housing 1 through the discharge passage 66.

[0053] Next, use Figure 4 A modification of the grease supply structure of the bearing of the second embodiment will be described. It should be noted that, for components having the same reference numerals as those in the first embodiment, their functions are the same, so their description is sometimes omitted below. The grease supply structure of this modification has a plurality of first grease supply passages 55 and a plurality of second grease supply passages 61.

[0054] like Figure 4 As shown, the grease supply structure of this modified example has two first grease supply passages 55, 55 and second grease supply passages 61, 61 respectively corresponding to the two first grease supply passages 55, 55. The two first grease supply passages 55, 55 are provided at positions opposite to each other across the first rotating body 3. The two second grease supply passages 61, 61 are provided at positions opposite to each other across the first rotating body 3.

[0055] Next, use Figure 5The grease supply structure of the bearing of the third embodiment of the present invention will be described. It should be noted that, for the components having the same reference numerals as those in the first embodiment, their functions are the same, so their description is sometimes omitted below. In the grease supply structure of the third embodiment, the structure of the first sealed space 57 is different from that of the first embodiment.

[0056] like Figure 5 As shown in the figure, the annular fifth seal 78 is provided between the housing 1 and the first rotating body 3 in such a manner that a gap is formed between the fifth seal 78 and the outer bearing 2. Typically, the fifth seal 78 is provided in such a manner that a gap is formed between the fifth seal 78 and the first bearing 27. Thus, a first sealed space 57 is formed between the first seal 58 of the first bearing 27 and the fifth seal 78. That is, in the third embodiment, the fifth seal 78 is provided between the housing 1 and the first rotating body 3 in such a manner that a gap is formed between the fifth seal 78 and the sealing member provided in the outer bearing 2. In this way, the outer bearing 2 is arranged adjacent to the first sealed space 57.

[0057] It should be noted that the outer bearing 2 is a bearing having an outer ring spacer 31 and an inner ring spacer 34, but may also be a normal ball bearing. In this case, a sealing member is provided on the outer bearing.

[0058] Next, use Figure 6 A modification of the grease supply structure of the bearing of the third embodiment will be described. It should be noted that, for components having the same reference numerals as those in the first embodiment, their functions are the same, so their description is sometimes omitted below. The grease supply structure of this modification has a plurality of first grease supply passages 55 and a plurality of second grease supply passages 61.

[0059] like Figure 6 As shown, the grease supply structure of this modified example has two first grease supply passages 55, 55 and second grease supply passages 61, 61 respectively corresponding to the two first grease supply passages 55, 55. The two first grease supply passages 55, 55 are provided at positions opposite to each other across the first rotating body 3. The two second grease supply passages 61, 61 are provided at positions opposite to each other across the first rotating body 3.

[0060] It should be noted that the present invention is not limited to the above-described embodiments and modifications, and modifications and improvements within the scope that can achieve the object of the present invention are included in the present invention.

[0061] For example, in each of the above-described embodiments and modifications, the number of the second grease supply passages 61 may be greater than the number of the first grease supply passages 55 .

[0062] Description of Reference Numerals

[0063] 1. Housing; 2. Outer bearing; 3. First rotating body; 4. Inner bearing; 5. Second rotating body; 27. First bearing; 28. Second bearing; 29. ​​Outer ring of first bearing; 30. Outer ring of second bearing; 31. Outer ring spacer; 32. Inner ring of first bearing; 33. Inner ring of second bearing; 34. Inner ring spacer; 55. First grease supply passage; 57. First sealing space; 58. First sealing member; 59. Second sealing member; 60. Outer through hole; 61. Second grease supply passage; 62. Inner through hole; 63. Second sealing space; 65. Exposed surface; 66. Exhaust passage; 76. First part; 77. Second part.

Claims

1. A grease supply structure for a bearing, comprising: A hollow shell; An outer bearing, the outer ring of which is held on the inner circumference of the housing; a first rotating body which is hollow and fixed to the inner ring of the outer bearing; an inner bearing, the outer ring of which is held on the inner peripheral surface of the first rotating body; and a second rotating body fixed to the inner ring of the inner bearing, The housing has a first grease supply passage for circulating lubricant supplied to the inner bearing. The downstream side of the first grease supply passage is communicated with a first sealed space sealed between the housing and the first rotating body. The first rotating body has a second grease supply passage connected to the first sealed space at its upstream side. The downstream side of the second grease supply passage communicates with a second sealed space sealed between the first rotating body and the second rotating body. The inner bearing is arranged in the second sealed space.

2. The grease supply structure of the bearing according to claim 1, wherein: The first rotating body has an exposed surface exposed from the housing. An outlet of a discharge passage for discharging the lubricant in the second sealed space to the outside of the housing opens at the exposed surface.

3. The grease supply structure of the bearing according to claim 1 or 2, wherein: The outer bearing has a first bearing and a second bearing adjacent to each other, an outer ring spacer connecting the outer ring of the first bearing and the outer ring of the second bearing, and an inner ring spacer connecting the inner ring of the first bearing and the inner ring of the second bearing. One axial end of the cylindrical gap between the outer ring spacer and the inner ring spacer is sealed by a first seal, and the other axial end of the cylindrical gap is sealed by a second seal. The cylindrical gap sealed by the first sealing member and the second sealing member is the first sealed space. The downstream side of the first grease supply passage is connected to the first sealed space via an outer through hole provided in the outer ring spacer. The upstream side of the second grease supply passage communicates with the first sealed space via an inner through hole provided in the inner race spacer.

4. The grease supply structure of the bearing according to claim 1 or 2, wherein: The outer bearing is arranged in the first sealed space in such a manner that a first portion on one axial end side of the first sealed space and a second portion on the other axial end side of the first sealed space are left. The downstream side of the first grease supply passage is connected to the first part, The upstream side of the second grease supply passage communicates with the second portion.

5. The grease supply structure of the bearing according to claim 1 or 2, wherein: The outer bearing is arranged adjacent to the first sealed space.

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