CAGE UNIT AND CONTROL ROLLER BEARING EQUIPPED WITH THE CAGE UNIT

Abstract

Cage unit (6) with: a cage (2) comprising a small-diameter side ring section (7), a large-diameter side ring section (8) arranged to be spaced axially apart from the small-diameter side ring section (7), and a plurality of cage rod sections (9) connecting the small-diameter side ring section (7) and the large-diameter side ring section (8); and a tapered roller (5) which is housed in a pocket (10) which is a space enclosed by the small diameter side ring section (7), the large diameter side ring section (8) and the cage rod section (9); wherein a lubrication groove (11) lying along a circumferential direction on an inner end surface (8a) of the side ring section of large diameter (8), which is opposite a large roller end surface (5a) of the tapered roller (5), is formed, a circumferential length of the lubrication groove (11) is designed such that the lubrication groove (11) is brought into circumferential contact with the large roller end surface (5a) of the tapered roller (5), and the lubrication groove (11) is positioned on a radially outer side of a pitch circle (C) of the large roller end surface (5a) of the tapered roller (5), characterized in that the lubrication groove (11) comprises a circumferentially extending short side (11a), a long side (11b) lying on a radially inner side of the short side (11a) which has a longer circumferential length than the short side (11a), and a coupling side (11c) which connects the ends of the short side (11a) and long side (11b), wherein an opening of the lubrication groove (11) is substantially trapezoidal in shape.

Description

BACKGROUND OF THE INVENTION 1. Scope of the invention

[0001] The invention relates to a cage unit and a tapered roller bearing equipped with the cage unit. More precisely, the invention relates to a cage unit with a lubrication groove for receiving the lubricating oil, and a tapered roller bearing equipped with the cage unit. 2. Description of the related technology

[0002] A tapered roller bearing was commonly used to configure a rotary support unit in various types of mechanical devices. In such a tapered roller bearing, a sliding section exists between the end face of a tapered roller and the ribbed end face of an inner or outer ring. The contact condition of both end faces in the sliding section is a rolling contact with sliding. Thus, if the lubricating oil supplied to the bearing becomes scarce or disappears, seizing on the end faces can easily occur.

[0003] During operation of the mechanical device, the lubricating oil is distributed and delivered to the bearing due to the stirring of the oil and similar processes that occur during the rotation of a shaft. If the mechanical device is stopped but immediately restarted, the lubricating oil remaining on both end faces can maintain lubrication, thus preventing seizing.

[0004] However, if the mechanical device is stopped and restarted after a considerable period of time, the lubricating oil adhering to both end surfaces flows down due to gravity, and the lubricating oil becomes scarce or disappears completely. This easily leads to seizing.

[0005] The formation of a groove for an oil sump in a cage holding a plurality of tapered rollers at predetermined intervals along a circumferential direction has already been proposed (see, for example, JP 2007 - 32 612 A). Fig. 4A is a perspective partial view of a cage 20 in a roller bearing described in JP 2007 - 32 612 A. Fig. Figure 4B is a partial top view of the same. In the cage 20 described in JP 2007-32612A, a circumferential groove 23, located along a circumferential direction, is formed on the inner end surface 21a opposite a pocket 22 of a large-diameter end 21 of the cage 20. It is assumed that seizing is prevented because the lack of lubricating oil at the time of commissioning after a long period of inactivity is alleviated by the lubricating oil absorbed in the circumferential groove 23. Fig. 4A and Fig. 4B designates a reference number 24 a cage bar section that connects a small diameter end 25 and a large diameter end 21 of the cage 20.

[0006] As in Fig. As can be seen in Figure 5, the circumferential groove 23 in the roller bearing described in JP 2007-32612A extends over the entire inner end surface 21a facing the pocket. Thus, the sections 23a near both ends of the circumferential groove 23 are not opposite the end surface of the tapered roller 26 and are open. If an operating stop condition continues for a long period, the lubricating oil will flow, albeit gradually, down from the sections 23a near both ends of the circumferential groove 23, which can lead to a shortage or complete lack of lubricating oil and potentially cause seizing at the time of restart.

[0007] DE 103 11 566 A1 further discloses a roller bearing cage for roller bearings, with a plurality of pockets defined by circular ring regions in the axial direction and support regions in the circumferential direction. The inner surface of each circular ring region, which faces the end face of a tapered roller, has a hollow region (a type of groove). SUMMARY OF THE INVENTION

[0008] One of the objectives of the present invention is to provide a cage unit that can supply the lubricating oil even at the time of commissioning after a long period of inactivity and increase resistance to seizing, and to provide a tapered roller bearing equipped with a cage unit.

[0009] According to one aspect of the present invention, a cage unit comprises a cage with a small-diameter side ring section, a large-diameter side ring section arranged to be spaced axially apart from the small-diameter side ring section, and a plurality of cage rod sections connecting the small-diameter side ring section and the large-diameter side ring section; and a tapered roller housed in a pocket which is a space enclosed by the small-diameter side ring section, the large-diameter side ring section, and the cage rod section.In the cage unit, a circumferential lubrication groove is formed on an inner end face of the large-diameter side ring section, opposite a large end face of the tapered roller. A circumferential length of the lubrication groove is designed such that it overlaps the large end face of the tapered roller in the circumferential direction. The lubrication groove is positioned on a radially outer side of a pitch circle of the large end face of the tapered roller. The lubrication groove has a circumferentially extending short side, a long side located on a radially inner side of the short side (with a longer circumferential length than the short side), and a coupling side connecting the ends of the short and long sides. An opening of the lubrication groove is essentially trapezoidal in shape. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The preceding and further features and advantages of the invention are evident from the following description of the exemplary embodiments with reference to the accompanying drawings, wherein the same reference numerals are used to represent the same elements, and wherein: Fig. 1 is an illustrative cross-sectional view of an embodiment of a tapered roller bearing of the present invention; Fig. 2 an explanatory perspective view of a cage in the tapered roller bearing which is in Fig. 1 is visible; Fig. 3 is an explanatory side view of the cage, which is in Fig. 2 can be seen; Fig. 4A is a perspective partial view of a cage using a related technique, and Fig. 4B is a partial top view of the same; and Fig. 5 is an explanatory side view of the cage of the related technique. DETAILED DESCRIPTION OF THE EXECUTION FORMS

[0011] An embodiment of a cage unit and a tapered roller bearing equipped with the cage unit according to the present invention is described in detail below with reference to the accompanying drawings. Fig. Figure 1 is an illustrative cross-sectional view of a tapered roller bearing 1 according to an embodiment of the present invention. Fig. Figure 2 is an explanatory perspective view of a cage 2 in the tapered roller bearing 1, which is in Fig. 1 can be seen.

[0012] The tapered roller bearing 1 according to the present embodiment comprises an outer ring 3, an inner ring 4, a plurality of tapered rollers 5, and a cage 2. The outer ring 3 has a conical raceway surface 3a on an inner circumferential side. The inner ring 4 has a conical raceway surface 4a on an outer circumferential side, which faces the raceway surface 3a. The tapered rollers 5 are arranged in an annular space between the raceway surface 3a and the raceway surface 4a. The cage 2 holds the tapered rollers 5 at predetermined intervals along the circumferential direction. The cage 2 and the tapered rollers 5 form a cage unit 6. The inner ring 4 is arranged radially inside the outer ring 3 and is rotatable relative to the outer ring 3.A conical rear rib section (hereinafter referred to as a large rib section) 4b is formed on a large diameter side of the raceway surface 4a of the inner ring 4, and a conical front rib section (hereinafter referred to as a small rib section) 4c is formed on a small diameter side of the raceway surface 4a.

[0013] The cage 2 comprises a small-diameter side ring section 7, a large-diameter side ring section 8, and a plurality of cage rod sections 9. The large-diameter side ring section 8 is arranged such that it is axially spaced from the small-diameter side ring section 7. The cage rod sections 9 connect the ring sections. As shown in Fig. As can be seen in Figure 2, the cage 2 as a whole has an annular, frustoconical shape, with a plurality of pockets 10 formed at equal intervals along the circumferential direction between the adjacent cage bar sections 9. The tapered roller 5 is held in the pocket 10 in a freely rotatable manner. The cage 2 can be made of a synthetic resin characterized by oil resistance, such as glass fiber-reinforced PPS; however, it can also be made of an iron-based metal.

[0014] A lubrication groove 11, located along the circumferential direction, is formed on an inner end surface 8a of the large-diameter side ring section 8 of the cage 2. The inner end surface 8a of the large-diameter side ring section 8 is the end surface that faces and is in contact with a large roller end surface 5a of the tapered roller 5. As shown in Fig. As can be seen in Figure 3, the circumferential length of the lubrication groove 11 is designed such that the lubrication groove 11 overlaps the large end face 5a of the tapered roller 5 in the circumferential direction. Thus, when the device equipped with the tapered roller bearing 1 is stopped, an opening of the lubrication groove 11 is brought into contact with the large end face 5a of the tapered roller 5, as if it were covered by the large end face 5a. In other words, the lubricating oil is held between the large end face 5a of the tapered roller 5 and the cage 2 by surface tension of the lubricating oil. Therefore, even if the device is restarted after a long period of inactivity, the lubricating oil contained in the lubrication groove 11 cannot flow out. Consequently, seizing, which could otherwise occur due to a lack of lubricating oil, is prevented at the time of restart.

[0015] As in Fig. As can be seen in Figure 3, the lubrication groove 11 in the present embodiment is located on a radially outer side (upper side in Fig. 3) of a partial circle C of the large end face 5a of the tapered roller 5. The lubrication groove 11 has a short side 11a extending in a circumferential direction, a long side 11b, and coupling sides 11c. The long side 11b is positioned on the radially inner side of the short side 11a and has a longer circumferential length than the short side 11a. The coupling sides 11c connect the ends of the short side 11a and the long side 11b. The opening of the lubrication groove 11, enclosed by the short side 11a, the long side 11b, and the coupling side 11c, is essentially trapezoidal. The coupling side 11c is a curved line (circular arc) that runs essentially parallel to an edge 5b, i.e., a circular edge of the large end face 5a of the tapered roller 5.Thus, a minimal thickness can be made thick and manufacturing by forming can be advantageously carried out, furthermore increasing the capacity of the lubrication groove 11.

[0016] In the present embodiment, a circumferential length w between the coupling side 11c and the edge of the large end face 5a of the tapered roller 5 is fixed such that it is longer than the relative distance of movement in the circumferential direction between the tapered roller 5 and the pocket 10. Thus, even if the tapered roller 5 is stopped and deviates circumferentially to any side in the pocket 10, the opening of the lubrication groove 11 can be reliably covered by the large end face 5a of the tapered roller 5. Therefore, the lubricating oil can be reliably prevented from flowing out of the lubrication groove. According to the invention, the circumferential length w between the coupling side 11c and the edge of the large end face 5a of the tapered roller 5 is not particularly limited and can, for example, be approximately 0.5 mm.

[0017] The lubrication groove 11 is accessible in both the vertical direction (upwards and downwards) Fig.3) as well as in the circumferential direction essentially in the center of the inner end surface 8a of the side ring section of large diameter 8. The height h1 of the lubrication groove 11 is approximately one-third of the height h2 of the inner end surface 8a. The length L1 of the short side 11a of the lubrication groove 11 along the circumferential direction is approximately two-thirds of the length L2 of the inner end surface 8a along the circumferential direction. According to the invention, the size and depth of the opening of the lubrication groove 11 are not particularly restricted and can be selected appropriately within a range so that a predetermined strength is ensured with regard to the material, size, and the like of the cage 2.

[0018] The embodiment disclosed herein is considered in all aspects to be merely illustrative and not limiting. The scope of the invention is defined by the appended claims and not by the preceding description, and all modifications that fall within the meaning and scope of the equivalence of the claim are intended to be included therein.

[0019] For example, in the embodiment described above, the opening of the lubrication groove is essentially trapezoidal; however, it can also assume other shapes, such as an oval shape or a strip-like shape. Furthermore, the coupling sides connecting the short and long sides of the lubrication groove are curved lines in the embodiment described above; however, they can also be formed by straight lines.

[0020] According to the cage unit and the tapered roller bearing equipped with the cage unit of the present invention, the lubricating oil can even be supplied at the time of commissioning after a long period of inactivity, thereby increasing the resistance to seizing.

Claims

[1] Cage unit (6) with: a cage (2) comprising a small-diameter side ring section (7), a large-diameter side ring section (8) arranged to be spaced axially apart from the small-diameter side ring section (7), and a plurality of cage rod sections (9) connecting the small-diameter side ring section (7) and the large-diameter side ring section (8); and a tapered roller (5) which is housed in a pocket (10) which is a space enclosed by the small diameter side ring section (7), the large diameter side ring section (8) and the cage rod section (9); wherein a lubrication groove (11) lying along a circumferential direction on an inner end surface (8a) of the side ring section of large diameter (8), which is opposite a large roller end surface (5a) of the tapered roller (5), is formed, a circumferential length of the lubrication groove (11) is designed such that the lubrication groove (11) is brought into circumferential contact with the large roller end surface (5a) of the tapered roller (5), and the lubrication groove (11) is positioned on a radially outer side of a pitch circle (C) of the large roller end face (5a) of the tapered roller (5), characterized by , that the lubrication groove (11) comprises a circumferentially extending short side (11a), a long side (11b) lying on a radially inner side of the short side (11a) which has a longer circumferential length than the short side (11a), and a coupling side (11c) which connects the ends of the short side (11a) and long side (11b), wherein an opening of the lubrication groove (11) is substantially trapezoidal in shape. [2] Cage unit (6) according to claim 1, wherein a circumferential length between the coupling side (11c) and an edge of the large roller end surface (5a) of the tapered roller (5) is longer than a relative movement distance in a circumferential direction between tapered roller (5) and pocket (10). [3] Cage unit (6) according to claim 1 or 2, wherein the coupling side (11c) is a curved line which is substantially parallel to the edge of the large roller end surface (5a) of the tapered roller (5). [4] Cage unit according to claim 1 or 2, wherein the coupling side (11c) is a straight line. [5] Tapered roller bearing (1) with: an outer ring (3); and an inner ring (4) which is arranged radially inside the outer ring (3) and is rotatable relative to the outer ring (3); characterized by : a cage unit (6) according to one of claims 1 to 4, which is arranged in an annular space between the outer ring (3) and the inner ring (4).

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