Bearing mounting structure

Abstract

To provide a bearing mounting structure capable of suppressing deterioration of durability due to relative slippage between a rolling bearing and a support member for supporting the rolling bearing.SOLUTION: A bearing mounting structure 1 comprises: a fixed cylindrical member 2; a first rotational shaft 3 inserted inside the cylindrical member 2; a first rolling bearing 4 that holds the first rotational shaft 3 rotatably relative to the cylindrical member 2; a second rotational shaft 5 that is formed in a cylindrical manner, and inside which the cylindrical member 2 is inserted; and a second rolling bearing 6 that holds the second rotational shaft 5 rotatably between itself and the cylindrical member 2. One of the first rolling bearing 4 and the second rolling bearing 6 is press-fitted into the cylindrical member 2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a structure in which a shaft member is rotatably mounted to a fixed member by a bearing. [Background technology]

[0002] Patent Document 1 describes a rolling bearing designed to extend its lifespan by maintaining its creep prevention function. The rolling bearing in Patent Document 1 includes an outer ring, an inner ring, and multiple spherical rolling elements between the outer and inner rings. The outer ring is attached to a housing or the like. The inner ring is fitted onto a rotating shaft. In the rolling bearing of Patent Document 1, a recessed groove is formed around the entire periphery of the outer ring along the circumferential direction of the outer ring. A metal annular coil spring is provided in the recessed groove. The coil spring protrudes radially outward from the outer peripheral surface of the outer ring. Therefore, when the outer ring is attached to the housing, the protruding portion functions as an interference. In other words, the coil spring deforms and generates elastic force, causing the compressed coil spring to contact the outer ring and the housing with a predetermined interference. This suppresses relative slippage between the outer ring and the housing, thereby suppressing wear (creep) between the outer ring and the housing. In Patent Document 1, a metal annular coil spring is used as the elastic member provided in the groove of the outer ring, and it is therefore claimed that deterioration of the elastic member and the generation of wear powder that occurs when the elastic member wears can be suppressed compared to when the elastic member is an O-ring made of rubber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-257346 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, the rolling bearings described in Patent Document 1 may be arranged radially one on top of the other to form a so-called double ring structure, thereby rotatably holding two shaft members relative to one housing. For example, one shaft member may penetrate the interior of a cylindrical housing, and the other cylindrical shaft member may be arranged radially outside the housing. In this case, one shaft member may penetrate the interior of one rolling bearing, and the one rolling bearing may be held inside the housing, thereby rotatably holding one shaft member. Furthermore, the other rolling bearing may be arranged inside the other shaft member, and the housing may penetrate the interior of the other rolling bearing, thereby rotatably holding the other shaft member. Such a double ring structure not only rotatably holds two shaft members, but also enables the overall device to be made smaller.

[0005] In a double ring structure configured in this manner, when the rolling bearing described in Patent Document 1 is used as the other rolling bearing, the other rolling bearing is fitted onto the other shaft member. In order to prevent a gap from occurring between the inner peripheral surface of the inner ring of the other rolling bearing and the outer peripheral surface of the housing, it is conceivable to form the above-mentioned groove on the inner peripheral surface of the inner ring and place an elastic member in the groove.

[0006] However, forming a groove on the inner peripheral surface of the inner ring and arranging an elastic member in the groove, as described in Patent Document 1, makes manufacturing the rolling bearing more difficult and potentially increases costs compared to forming a groove on the outer peripheral surface of the outer ring and arranging an elastic member in the groove. Furthermore, in the double ring structure described above, when the shaft member vibrates in the radial direction due to input torque, the elastic member elastically deforms, causing the elastic member to slide against the housing and wear. In such cases, wear debris may invade the rolling surfaces of the rolling elements in the rolling bearing, potentially reducing the durability of the rolling bearing. Furthermore, forming such a groove reduces the load that the rolling bearing can withstand as a whole. Therefore, there is still room for improvement in the double ring structure described above in order to suppress relative sliding between the rolling bearing and the housing while avoiding a complex structure and reducing the durability of the rolling bearing.

[0007] This invention has been made in light of the above technical problems, and aims to provide a bearing mounting structure that can suppress a decrease in durability due to relative slippage between a rolling bearing and a support member that supports the rolling bearing. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the present invention provides a bearing mounting structure comprising a fixed cylindrical member, a first rotating shaft inserted inside the cylindrical member, a first rolling bearing arranged between the first rotating shaft and the cylindrical member and holding the first rotating shaft rotatably relative to the cylindrical member, a second rotating shaft formed in a cylindrical shape and having the cylindrical member inserted inside it, and a second rolling bearing arranged between the second rotating shaft and the cylindrical member and holding the second rotating shaft rotatably relative to the cylindrical member, wherein one of the first rolling bearing and the second rolling bearing is press-fitted into the cylindrical member.

[0009] The present invention may also provide a bearing mounting structure comprising: a fixed cylindrical member; a first rotating shaft inserted inside the cylindrical member; a first rolling bearing arranged between the first rotating shaft and the cylindrical member and holding the first rotating shaft rotatably relative to the cylindrical member; a second rotating shaft formed in a cylindrical shape and having the cylindrical member inserted inside it; and a second rolling bearing arranged between the second rotating shaft and the cylindrical member and holding the second rotating shaft rotatably relative to the cylindrical member, wherein torque is input to at least one of the first rotating shaft and the second rotating shaft.

[0010] In the present invention, the second rolling bearing may be disposed radially outward of the first rolling bearing. [Effects of the Invention]

[0011] In this bearing mounting structure, a first rotating shaft inserted into a fixed cylindrical member is rotatably held relative to the cylindrical member by a first rolling bearing. Furthermore, a cylindrical second rotating shaft inserted into the cylindrical member is rotatably held relative to the cylindrical member by a second rolling bearing. That is, the bearing mounting structure has a double ring structure in which two rotating shafts are rotatably held relative to one cylindrical member by respective rolling bearings. One of the first rolling bearing and the second rolling bearing is fitted into the cylindrical member by press-fitting in the radial direction. Therefore, the cylindrical member is subjected to a radial load due to the press-fitting, causing it to deform and bend radially. As a result, it is possible to prevent or suppress the formation of a gap between the cylindrical member and the other of the first rolling bearing and the second rolling bearing. That is, because the other rolling bearing and the cylindrical member are in close contact or press-fitted, relative rotation between the other rolling bearing and the cylindrical member is suppressed, thereby suppressing a decrease in durability due to wear (creep). Furthermore, since no new processing or addition of members is required for the first rolling bearing and the second rolling bearing, the above-mentioned effects can be achieved while suppressing increases in costs.

[0012] Furthermore, in the above-described dual-column bearing mounting structure, torque is input to at least one of the first rotating shaft and the second rotating shaft. When the torque is transmitted, a radial load is transmitted due to, for example, vibrations generated when the actuator outputs torque or backlash in a gear pair provided on the torque transmission path. If the first rotating shaft or the second rotating shaft vibrates in the radial direction due to such a radial load, the load causes housing 2 to deform radially inward. This prevents or reduces the generation of a gap between the cylindrical member and the first or second rolling bearing, further reducing wear between the cylindrical member and the first or second rolling bearing.

[0013] Furthermore, the first rolling bearing and the second rolling bearing overlap each other at least partially in the radial direction. Therefore, when the cylindrical member is deformed as described above, the first rolling bearing or the second rolling bearing is located at a position where the deformation occurs relatively significantly. This effectively prevents a gap from being generated between the cylindrical member and the first rolling bearing or the second rolling bearing. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a cross-sectional view illustrating an example of a mounting structure for a bearing according to an embodiment of the present invention. [Figure 2] FIG. 10 is a cross-sectional view illustrating another example of the mounting structure of the bearing according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] The present invention will be described below based on the embodiments shown in the drawings. Note that the embodiments described below are merely examples of specific embodiments of the present invention, and are not intended to limit the present invention.

[0016] An example of a bearing mounting structure according to an embodiment of the present invention will be described with reference to Fig. 1. In the bearing mounting structure according to an embodiment of the present invention, two rolling bearings are arranged, and the two rolling bearings are configured to rotatably support two rotating shafts relative to one fixed member. The bearing mounting structure 1 shown in Fig. 1 is a structure in which, for example, bearings are arranged on a case constituting a vehicle transmission so as to rotatably support the two rotating shafts. The bearing mounting structure 1 shown in Fig. 1 includes a housing 2, a first rotating shaft 3, a first rolling bearing 4, a second rotating shaft 5, and a second rolling bearing 6.

[0017] The housing 2 is a cylindrical member formed to hold the first rotating shaft 3 and the second rotating shaft 5. The housing 2 is, for example, a cylindrical portion protruding from a case (not shown) in the axial direction of the first rotating shaft 3 and the second rotating shaft 5. The first rotating shaft 3 that passes through the housing 2 and a first rolling bearing 4 that rotatably supports the first rotating shaft 3 are arranged on the inner peripheral side of the housing 2. Furthermore, the second rotating shaft 5 that is arranged so that the housing 2 passes through the interior thereof and a second rolling bearing 6 that rotatably supports the second rotating shaft 5 are arranged on the outer peripheral side of the housing 2. The housing 2 corresponds to the cylindrical member in this embodiment of the present invention.

[0018] The first rotating shaft 3 is a solid rotating shaft that rotates when torque is transmitted to it, etc. The first rotating shaft 3 is connected to, for example, the output shaft of a driving force source such as an engine or a motor, or the output shaft of a transmission, and rotates when the output torque of the driving force source is transmitted to it.

[0019] The first rolling bearing 4 may be configured similarly to conventionally known rolling bearings, and rotatably supports the first rotating shaft 3. As shown in FIG. 1, the first rolling bearing 4 has a first inner ring 4a, a first outer ring 4b, and a plurality of first rolling elements (rollers) 4c. The above-mentioned first rotating shaft 3 penetrates the inside of the first inner ring 4a. In addition, a plurality of first rolling elements 4c are arranged at equal intervals on the outer periphery of the first inner ring 4a.

[0020] The first rolling elements 4c are disposed between the first inner ring 4a and the first outer ring 4b and roll on the outer peripheral surface of the first inner ring 4a and the inner peripheral surface of the first outer ring 4b. The first rolling bearing 4 is provided with a first cage (not shown) for holding the first rolling elements 4c. The first cage accommodates the first rolling elements 4c so that they can rotate. The first cage also holds the first rolling elements 4c at a predetermined interval in the circumferential direction. The first cage configured in this manner allows the first rolling elements 4c to roll on the outer peripheral surface of the first inner ring 4a and the inner peripheral surface of the first outer ring 4b while maintaining a predetermined interval in the circumferential direction. The first rolling elements 4c enable relative rotation between the first inner ring 4a and the first outer ring 4b. For ease of explanation, only two of the first rolling elements 4c are shown in the figure. The first cage is integrally formed with the first inner ring 4a and the first outer ring 4b.

[0021] The first outer ring 4b is disposed on the outer peripheral side of the multiple first rolling elements 4c, and is disposed so that the outer peripheral surface of the first outer ring 4b faces the inner peripheral surface of the housing 2. As shown in Fig. 1, the housing 2 that holds and positions the first rolling bearing 4 is disposed radially outward of the first outer ring 4b. Therefore, the contact of the first outer ring 4b with the housing 2 suppresses radial movement of the first rolling bearing 4, and therefore the first rotating shaft 3 can be positioned radially.

[0022] The second rolling bearing 6 may be configured similarly to the first rolling bearing 4, and is disposed radially outward of the housing 2. As shown in FIG. 1, the second rolling bearing 6 has a second inner ring 6a, a second outer ring 6b, and a plurality of second rolling elements (rollers) 6c. The housing 2 described above passes through the interior of the second inner ring 6a. Furthermore, a plurality of second rolling elements 6c are disposed at equal intervals on the outer periphery of the second inner ring 6a.

[0023] The second rolling elements 6c are disposed between the second inner ring 6a and the second outer ring 6b and roll on the outer circumferential surface of the second inner ring 6a and the inner circumferential surface of the second outer ring 6b. The second rolling bearing 6 is provided with a second cage (not shown) for holding the second rolling elements 6c. The second cage rotatably accommodates the second rolling elements 6c. The second cage also holds the second rolling elements 6c at a predetermined interval in the circumferential direction. The second cage configured in this manner allows the second rolling elements 6c to roll on the outer circumferential surface of the second inner ring 6a and the inner circumferential surface of the second outer ring 6b while maintaining the predetermined interval in the circumferential direction. Note that for convenience of explanation, only two of the second rolling elements 6c are shown. The second cage is also integrally formed with the second inner ring 6a and the second outer ring 6b.

[0024] The second outer ring 6b is disposed on the outer peripheral side of the plurality of second rolling elements 6c, and is disposed so that the outer peripheral surface of the second outer ring 6b faces the inner peripheral surface of the second rotating shaft 5. As shown in Fig. 1, the second rotating shaft 5, which is rotatably held by the second rolling bearing 6, is disposed radially outward of the second outer ring 6b.

[0025] The second rotating shaft 5 is a hollow rotating shaft that rotates when torque is transmitted to it, etc. The second rotating shaft 5 is connected to, for example, the output shaft of a driving force source such as an engine or a motor, or the output shaft of a transmission, and rotates when the output torque of the driving force source is transmitted to it.

[0026] The first rolling bearing 4 and the second rolling bearing 6 are arranged so as to overlap at least partially in the radial direction. That is, the contact area between the inner circumferential surface of the housing 2 and the outer circumferential surface of the first outer ring 4b and the contact area between the outer circumferential surface of the housing 2 and the inner circumferential surface of the second inner ring 6a at least partially overlap in the radial direction.

[0027] Furthermore, the first rolling bearing 4 is fitted between the housing 2 and the first rotating shaft 3 by a clearance fit or the like. That is, the inner diameter of the housing 2 is slightly larger than the outer diameter of the first rolling bearing 4, leaving a slight gap between the outer peripheral surface of the first rolling bearing 4 and the inner peripheral surface of the housing 2. Furthermore, the second rolling bearing 6 is fitted into the housing 2 by an interference fit or the like in a press-fit state. That is, the outer diameter of the housing 2 and the inner diameter of the second inner ring 6a of the second rolling bearing 6 are approximately the same size, or the inner diameter of the second inner ring 6a of the second rolling bearing 6 is slightly smaller than the outer diameter of the housing 2. Therefore, when the second rolling bearing 6 is disposed on the outer peripheral side of the housing 2, the housing 2 is inserted into the second rolling bearing 6 under pressure. As a result, the outer peripheral surface of the housing 2 and the inner peripheral surface of the second inner ring 6a are in close contact with each other under a relatively large pressure.

[0028] As described above, in the bearing mounting structure 1, the first rotating shaft 3 is rotatably supported between the housing 2 and the first rolling bearing 4. The second rolling bearing 6 is disposed on the outer periphery of the housing 2. The housing 2 is press-fitted into the second rolling bearing 6. Therefore, the second rolling bearing 6 compresses the housing 2 radially inward, i.e., toward the first rolling bearing 4. This compression causes the housing 2 to deform toward the first rolling bearing 4. In other words, a load is applied to reduce the diameter. As a result, it is possible to prevent or suppress the formation of a gap between the housing 2 and the first outer ring 4b of the first rolling bearing 4. In other words, the inner circumferential surface of the housing 2 and the outer circumferential surface of the first outer ring 4b are in line contact or surface contact and tightly adhere or press-bonded, thereby suppressing relative rotation between the inner circumferential surface of the housing 2 and the outer circumferential surface of the first outer ring 4b. This makes it possible to prevent wear (creep) from occurring between the inner peripheral surface of the housing 2 and the outer peripheral surface of the first outer ring 4b. Furthermore, since the second rolling bearing 6 can be configured simply by press-fitting it into the housing 2 without requiring any additional machining or components for the first rolling bearing 4 or the second rolling bearing 6, it is possible to prevent an increase in costs.

[0029] Furthermore, the first rolling bearing 4 and the second rolling bearing 6 at least partially overlap each other in the radial direction. Because the second rolling bearing 6 is press-fitted into the housing 2 as described above, a radially inward load is applied to the contact portion of the outer surface of the housing 2 that is in line or surface contact with the inner surface of the second inner ring 6a. This causes the housing 2 to flex and deform radially inward around the contact portion. The first outer ring 4b of the first rolling bearing 4 is located at a portion radially inward of the contact portion. In other words, the outer surface of the first outer ring 4b is positioned at a portion that is most susceptible to deformation in the housing 2. That is, as shown in FIG. 1 , a first region W1, which is the region where the first outer ring 4b receives a load from the housing 2 in the axial direction, overlaps with a second region W2, which is the region where the second outer ring 6b applies a load to the housing 2 in the axial direction. This effectively prevents a gap from being formed between the outer surface of the first outer ring 4b and the inner surface of the housing 2. Therefore, the housing 2 is deformed by the second rolling bearing 6, effectively reducing the gap between the outer surface of the first rolling bearing 4 and the inner surface of the housing 2, thereby further suppressing wear between the inner surface of the housing 2 and the outer surface of the first outer ring 4b.

[0030] Furthermore, torque is input to the second rotating shaft 5 from a driving force source such as an engine or a motor. For example, when torque is transmitted to the second rotating shaft 5, a load is generated in the radial direction of the second rotating shaft 5 due to vibrations that occur when the driving force source outputs torque, backlash in a gear pair provided on the torque transmission path, or the electromagnetic force and weight of the motor, i.e., a radial load. When the second rotating shaft 5 vibrates in the radial direction due to such a radial load, the load is transmitted to the housing 2 via the second rolling bearing 6. This load deforms the housing 2 radially inward, further preventing or suppressing the generation of a gap between the housing 2 and the first outer ring 4b of the first rolling bearing 4. In other words, wear between the inner circumferential surface of the housing 2 and the outer circumferential surface of the first outer ring 4b can be further suppressed.

[0031] Next, another bearing mounting structure 1 according to an embodiment of the present invention will be described with reference to Figure 2. As shown in Figure 2, the other bearing mounting structure 1 has the same components as the other bearing mounting structure 1 shown in Figure 1. However, as shown in Figure 2, the other bearing mounting structure 1 is configured so that a load is generated by the first rotating shaft 3 to deform the housing 2 in the radial direction.

[0032] In another bearing mounting structure 1 shown in Figure 2, the second rolling bearing 6 configured as described above is fitted between the housing 2 and the second rotating shaft 5 by a clearance fit or the like. In other words, the outer diameter of the housing 2 is formed slightly larger than the inner diameter of the second rolling bearing 6, and a small gap is created between the inner peripheral surface of the second rolling bearing 6 and the outer peripheral surface of the housing 2.

[0033] Furthermore, the first rolling bearing 4 configured as described above is fitted into the housing 2 by being pressed in using an interference fit or the like. That is, the inner diameter of the housing 2 and the outer diameter of the first outer ring 4b of the first rolling bearing 4 are formed to be approximately the same size, or the outer diameter of the first outer ring 4b of the first rolling bearing 4 is formed to be slightly larger than the inner diameter of the housing 2. Therefore, when the first rolling bearing 4 is placed inside the housing 2, the first rolling bearing 4 is inserted into the housing 2 under pressure. As a result, the inner circumferential surface of the housing 2 and the outer circumferential surface of the first outer ring 4b are fitted together in close contact or pressure bonding with a relatively large pressure being applied.

[0034] With this configuration, the first rolling bearing 4 is press-fit into the housing 2, so that the housing 2 is pressed outward in the radial direction. Pressing outward in the radial direction causes the housing 2 to deform and flex toward the second rolling bearing 6, and the outer peripheral surface of the housing 2 and the inner peripheral surface of the second inner ring 6a come into line contact or surface contact, tightly adhering or being pressed together. This makes it possible to prevent wear (creep) from occurring between the outer peripheral surface of the housing 2 and the inner peripheral surface of the second inner ring 6a.

[0035] Furthermore, torque is input to the first rotating shaft 3 from a driving force source such as an engine or a motor. Therefore, when the first rotating shaft 3 vibrates in the radial direction due to the transmitted radial load as described above, the load is transmitted to the housing 2 via the first rolling bearing 4. This load causes the housing 2 to deform radially outward, further preventing or suppressing the generation of a gap between the housing 2 and the second inner ring 6a of the second rolling bearing 6. In other words, wear between the outer peripheral surface of the housing 2 and the inner peripheral surface of the second outer ring 6b can be further suppressed.

[0036] Although the embodiments of the present invention have been described above, the present invention is not limited to the above examples and may be modified as appropriate within the scope of achieving the object of the present invention. For example, the first rotating shaft 3 or the second rotating shaft 5 may be configured to receive torque from other actuators, etc., rather than from a driving power source such as an engine or motor as described above. In other words, it is sufficient that a mechanism capable of transmitting a radial load is connected to the first rotating shaft 3 or the second rotating shaft 5.

[0037] Furthermore, the above-described configuration may include at least one configuration for filling the gap with the first rolling bearing 4 or the second rolling bearing 6. For example, the bearing mounting structure 1 shown in Fig. 1 may include only one of the following: the second rolling bearing 6 is press-fitted into the housing 2; and a torque that vibrates the second rotating shaft 5 is input. Even with such a configuration, a load that causes deformation in the radial direction is input to the housing 2, so the above-described effects can be obtained. [Explanation of symbols]

[0038] 1 Bearing mounting structure 2. Housing 3 First rotation axis 4 First rolling bearing 5 Second rotation axis 6 Second rolling bearing W1 1st area W2 2nd area

Claims

1. a fixed cylindrical member; a first rotating shaft inserted into the cylindrical member; a first rolling bearing disposed between the first rotating shaft and the cylindrical member and configured to rotatably hold the first rotating shaft relative to the cylindrical member; a second rotating shaft formed in a cylindrical shape and having the cylindrical member inserted therein; a second rolling bearing disposed between the second rotating shaft and the cylindrical member and configured to rotatably hold the second rotating shaft relative to the cylindrical member, One of the first rolling bearing and the second rolling bearing is press-fitted into the cylindrical member. A bearing mounting structure characterized by:

2. a fixed cylindrical member; a first rotating shaft inserted into the cylindrical member; a first rolling bearing disposed between the first rotating shaft and the cylindrical member and configured to rotatably hold the first rotating shaft relative to the cylindrical member; a second rotating shaft formed in a cylindrical shape and having the cylindrical member inserted therein; a second rolling bearing disposed between the second rotating shaft and the cylindrical member and configured to rotatably hold the second rotating shaft relative to the cylindrical member, Torque is input to at least one of the first rotating shaft and the second rotating shaft. A bearing mounting structure characterized by:

3. The bearing mounting structure according to claim 1 or 2, The second rolling bearing is disposed radially outward of the first rolling bearing. A bearing mounting structure characterized by:

Images