Drive device

Abstract

To provide a structure in which a rolling bearing and a stationary side member are easy to become a fluid lubrication state, in a configuration for supplying oil between the rolling bearing and the stationary side member.SOLUTION: A drive device comprises a stationary side member, a rolling bearing, and a rotation side member that is drivingly connected to a drive source and supported on the stationary side member via the rolling bearing so as to be rotatable around an axis. The rolling bearing is press-fitted into one of the rotation side member and the stationary side member, and fitted into the other. On a surface of the rolling bearing that faces the other member in a radial direction, or on a surface of the other member that faces the rolling bearing in the radial direction, a groove capable of receiving oil is formed. The groove is formed so as to generate a wedge effect on oil flowing through a gap between the rolling bearing and the other member when the rotation side member is rotating in one direction.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a drive device. [Background technology]

[0002] A structure is known in which a lubrication groove extending in the axial direction and inclined with respect to the axial direction of a power transmission shaft is provided on the inner surface of a case into which the outer peripheral surface of an outer race of a rolling bearing is clearance-fitted, as a lubrication groove through which oil is supplied. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-034076 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, in a configuration in which oil is supplied between a rolling bearing and a fixed member (for example, a case), if a fluid lubrication state is not formed between the rolling bearing and the fixed member, there is a risk of wear being accelerated by creep, etc. In this regard, in the above-mentioned conventional technology, if the outer circumferential surface of the outer race of the rolling bearing and the case are not in a fluid lubrication state, and creep occurs in which the outer race of the rolling bearing rotates, there is a risk of the case wearing out.

[0005] In view of the above, in one aspect, the present disclosure has an object to provide a structure in which, in a configuration in which oil is supplied between a rolling bearing and a fixed-side member, the rolling bearing and the fixed-side member are likely to be in a fluid lubricated state. [Means for solving the problem]

[0006] In one aspect, a stationary member; A rolling bearing; a rotating-side member that is drivingly connected to a driving source and is rotatably supported on the fixed-side member via the rolling bearing so as to be rotatable about an axis, the rolling bearing is press-fitted into one of the rotating-side member and the fixed-side member and fitted into the other of the rotating-side member and the fixed-side member; A groove capable of receiving oil is formed on a surface of the rolling bearing that faces the other member in a radial direction, or on a surface of the other member that faces the rolling bearing in a radial direction, A drive device is provided in which the groove is formed so as to generate a wedge effect on oil flowing through a gap between the rolling bearing and the other member when the rotating side member is rotating in one direction. Effect of the Invention

[0007] According to one aspect, the present disclosure can provide a structure in which, in a configuration in which oil is supplied between a rolling bearing and a fixed-side member, the rolling bearing and the fixed-side member are likely to be in a fluid lubricated state. [Brief description of the drawings]

[0008] [Figure 1] 1 is a skeleton diagram of a vehicle drive system including a rotating electric machine and a power transmission mechanism. [Diagram 2] FIG. 2 is a schematic view of a bearing structure suitable for the vehicle drive device according to the present embodiment, as viewed in the axial direction. [Diagram 3] 5 is an explanatory diagram of a groove formed on the outer peripheral surface of the outer race. FIG. [Figure 4] FIG. 4 is an explanatory diagram of the inclination of the bottom of the groove, and is a cross-sectional view taken along line AA in FIG. 3. [Diagram 5] 6 is an explanatory diagram of a groove formed in the outer peripheral surface of an outer race of a bearing according to a first modified example. FIG. [Figure 6] 13 is an explanatory diagram of a groove formed in the outer peripheral surface of the outer race of a bearing according to a second modified example. FIG. [Figure 7] 13 is an explanatory diagram of a groove formed in the outer peripheral surface of the outer race of a bearing according to a third modified example. FIG. [Figure 8] FIG. 8 is a cross-sectional view taken along line DD in FIG. [Figure 9]FIG. 13 is an explanatory diagram of a groove according to a fourth modified example, which is an explanatory diagram of a groove that may be formed on the case side. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Each embodiment will be described in detail below with reference to the accompanying drawings. Note that the dimensional ratios in the drawings are merely examples and are not limiting, and shapes and the like in the drawings may be partially exaggerated for the sake of explanation. In addition, in the drawings, for ease of viewing, reference symbols may be given to only some of the parts that exist in a plurality of parts with the same attribute.

[0010] In the following, first, a vehicle drive system 100 to which the vehicle drive device 17 according to this embodiment can be suitably applied will be described, and then a bearing structure in the vehicle drive device 17 according to this embodiment will be described.

[0011] FIG. 1 is a skeleton diagram of a vehicle drive system 100 including a rotating electric machine 1 and a power transmission mechanism 7.

[0012] 1, a vehicle drive system 100 includes a rotating electric machine 1 that serves as a drive source for a vehicle, and a power transmission mechanism 7 provided in a power transmission path that connects the rotating electric machine 1 and wheels W. The power transmission mechanism 7 includes an input member 3, a counter gear mechanism 4, a differential gear mechanism 5, and left and right output members 6A, 6B.

[0013] The input member 3 has an input shaft 31 and an input gear 32. The input shaft 31 is a rotating member that rotates around the first axis A1. The input gear 32 is a gear that transmits rotational torque (driving force) from the rotating electric machine 1 to the counter gear mechanism 4. The input gear 32 is provided on the input shaft 31 of the input member 3 so as to rotate integrally with the input shaft 31 of the input member 3.

[0014] The counter gear mechanism 4 is disposed in the power transmission path between the input member 3 and the differential gear mechanism 5. The counter gear mechanism 4 has a counter shaft 41, a first counter gear 42, and a second counter gear 43.

[0015] The counter shaft 41 is a rotating member that rotates around the second shaft A2. The second shaft A2 extends parallel to the first shaft A1. The first counter gear 42 is an input element of the counter gear mechanism 4. The first counter gear 42 meshes with the input gear 32 of the input member 3. The first counter gear 42 is connected to the counter shaft 41 so as to rotate integrally therewith.

[0016] The second counter gear 43 is an output element of the counter gear mechanism 4. In the present embodiment, for example, the second counter gear 43 is formed to have a smaller diameter than the first counter gear 42. The second counter gear 43 is provided on the counter shaft 41 so as to rotate integrally with the counter shaft 41.

[0017] The differential gear mechanism 5 is disposed on a third axis A3 serving as the rotation axis thereof. The third axis A3 extends parallel to the first axis A1. The differential gear mechanism 5 distributes the driving force transmitted from the rotating electric machine 1 to left and right output members 6A and 6B. The differential gear mechanism 5 includes a differential input gear 51 that meshes with the second counter gear 43 of the counter gear mechanism 4. The differential gear mechanism 5 also includes a differential case 52 that houses a pinion shaft, a pinion gear, left and right side gears, etc. The left and right side gears are connected to the left and right output members 6A and 6B so as to rotate integrally therewith, respectively.

[0018] The left and right output members 6A, 6B are drivingly connected to the left and right wheels W, respectively. The left and right output members 6A, 6B transmit the driving force distributed by the differential gear mechanism 5 to the wheels W. Note that the left and right output members 6A, 6B may be constituted by two or more members.

[0019] In this way, the rotating electric machine 1 drives the wheels W via the power transmission mechanism 7. However, in other embodiments, other speed reduction mechanisms such as a planetary gear mechanism may be used.

[0020] 1, the case 2 and various components in the case 2 form a vehicle drive device 17 according to this embodiment. Note that a part or all of one or both of the left and right output members 6A and 6B may not be housed in the case 2.

[0021] The vehicle drive device 17 according to this embodiment is not limited to the vehicle drive system 100 having the specific configuration shown in Fig. 1, but can be applied to various vehicle drive systems. The vehicle drive device 17 can be applied to any vehicle drive system as long as it has at least one rotating member that is drivingly connected to the wheel W in a manner that allows power from a drive source (e.g., a rotating electric machine 1 or an engine) to be transmitted to the wheel W.

[0022] Next, a characteristic configuration of the vehicle drive device 17 according to this embodiment will be described with reference to FIG. 2 and subsequent figures.

[0023] Fig. 2 is an explanatory diagram of a bearing structure 9 suitable for a vehicle drive device 17 according to this embodiment, and is a schematic diagram viewed in the axial direction. In Fig. 2, an X direction, and an X1 side and an X2 side along the X direction are defined as a direction perpendicular to a first axis A1. Note that the X direction may approximately correspond to, for example, the horizontal direction.

[0024] In the following, the bearing structure 9 will be described using an example in which it is applied to a bearing 90 that rotatably supports the input shaft 31 shown in Figure 1, but the bearing structure 9 may also be applied to other bearings (not shown) that rotatably support other rotating side members in the vehicle drive device 17.

[0025] The input shaft 31, which is a rotating member, is press-fitted (interference-fitted) into the bearing 90, and is also clearance-fitted into the case 2, which is a fixed member. That is, the outer race 91 of the bearing 90 is clearance-fitted into the shaft hole of the case 2, and the input shaft 31 is press-fitted into the radially inner side of the inner race 92. Note that in the example shown in Fig. 2, the bearing 90 is a ball bearing, but it may be another type of rolling bearing that uses rollers or the like. Hereinafter, the surface of the bearing 90 that faces the case 2 in the radial direction is also referred to as the "outer peripheral surface of the outer race 91."

[0026] FIG. 3 is an explanatory diagram of the groove 96 formed on the outer peripheral surface of the outer race 91, and is a diagram showing the bearing 90 in a side view (viewed in the X direction from the X2 side, the same below) with a part of the case 2 in FIG. 2 (X1 side with respect to the line L200 in FIG. 2) and the input shaft 31 removed. Note that FIG. 3 also shows another part of the case 2 in FIG. 2 (X1 side with respect to the line L200 in FIG. 2). Also, in FIG. 3, the Y direction and the Y1 side and Y2 side along the Y direction are defined as directions parallel to the first axis A1. Also, in FIG. 3 (similarly to FIG. 5 and the like described later), oil is shown typically by a hatched area 80. FIG. 4 is an explanatory diagram of the inclination of the bottom of the groove 96, and is a cross-sectional view taken along the line AA in FIG. 3.

[0027] In this embodiment, the method of supplying oil to the bearing 90 is arbitrary. For example, in order to ensure an appropriate amount of oil is supplied radially between the outer race 91 of the bearing 90 and the case 2, an oil passage 36 may be provided that supplies oil from one axial side (the Y2 side in FIG. 3) of the bearing 90 to the adjacent space SP1. This allows the oil supplied to the space SP1 to be efficiently supplied radially between the outer race 91 of the bearing 90 and the case 2. Note that part or all of the oil passage 36 may be formed in the case 2, or may be formed by a tubular member separate from the case 2.

[0028] In this embodiment, an outer circumferential surface of an outer race 91 of a bearing 90 (the surface facing the case 2 in the radial direction) is formed with a groove 96 through which oil passes.

[0029] The groove 96 extends from one end to the other end in the axial direction of the bearing 90, and is open in the axial direction at both axial ends of the bearing 90. This can promote the supply of oil to the groove 96 of the bearing 90.

[0030] The grooves 96 are formed in a circumferential direction around the first axis A1 such that a central portion 961 and groove end portions 962 on both sides in the Y direction form a V shape (a V shape opening toward the bottom in the figure) in a side view. In this embodiment, the grooves 96 are formed at equal intervals (equal pitch) in the circumferential direction around the first axis A1, but in a modified example, the grooves 96 may be formed at two or more different pitches that change in the circumferential direction.

[0031] In the example shown in Fig. 3, the V-shape of the groove 96 is a straight V-shape in side view, but may be a V-shape including a curved shape (or a substantially U-shape). In the example shown in Fig. 3, the groove width w of the groove 96 is approximately constant, but may vary depending on the position in the axial direction. For example, the groove width w of the groove 96 at a central side portion 961 may be smaller than the groove width w at groove end portions 962 on both sides in the Y direction.

[0032] As shown in FIG. 4, the groove end 962 of the groove 96 has a depth H deeper than the center side portion 961. That is, the depth H of the groove 96 is not constant, and the groove end 962 is deeper than the center side portion 961. In this embodiment, as shown in FIG. 4, the depth H of the groove 96 decreases at a constant inclination toward the axially inner side, but is not limited to this. That is, the depth H of the groove 96 may decrease nonlinearly toward the axially inner side. In addition, in FIG. 4, the dimensions a and b represent dimensions with respect to a reference surface (for example, the surface of the case 2 at the nominal position), that is, gap dimensions with respect to the surface of the case 2 at the nominal position. The values ​​of the dimensions a and b increase as the depth H of the groove 96 increases. Therefore, in this embodiment, the gap (radial gap) between the groove 96 and the case 2 is more likely to be smaller at the center side portion 961 than at the groove end 962.

[0033] In FIG. 3, the arrow R30 shows a schematic representation of the rotation direction when the vehicle moves forward. In this embodiment, the groove end 962 of each groove 96 is located on the leading side in the rotation direction when the vehicle moves forward, relative to the center portion 961. That is, the V-shape of the groove 96 is oriented so that the trailing side is pointed in the rotation direction when the vehicle moves forward, as viewed from the side. Therefore, when the outer race 91 rotates relative to the case 2 as the vehicle moves forward, the oil pressure becomes higher in the center portion 961 than in the groove end 962. That is, when the input shaft 31 rotates when the vehicle moves forward, the oil is drawn into the center portion 961 of the narrow gap, generating a relatively high oil pressure in the center portion 961. In this way, according to this embodiment, each groove 96 can generate a wedge effect on the oil passing through the gap between the bearing 90 and the case 2 during rotation when the vehicle moves forward. This wedge effect makes it easier for the bearing 90 and the case 2 to be in a fluid lubrication state. As a result, wear of the case 2 caused by creep or the like can be reduced.

[0034] In this embodiment, as described above, the groove 96 is open on both axial sides in the axial direction, but is not limited to this. For example, the groove 96 may be in a form in which both axial sides or one axial side is closed (i.e., not open).

[0035] Next, various modified examples of the above-described embodiment will be described with reference to Fig. 5 onwards. In the following description, components that may be similar to those in the above-described embodiment will be given the same reference numerals and descriptions thereof may be omitted.

[0036] FIG. 5 is an explanatory diagram of a groove 96A formed in the outer peripheral surface of an outer race 91A of a bearing 90A according to a first modified example, and is a diagram similar to the above-mentioned FIG.

[0037] The groove 96A of the bearing 90A according to the first modified example has a configuration in which two groove portions 960A each having a V-shape in side view, like the groove 96 according to the above-described embodiment, are arranged side by side in the axial direction. In this manner, a plurality of groove portions 960A each having a V-shape in side view may be arranged side by side in the axial direction.

[0038] In the first modified example, the groove portion 960A of the groove 96A may have a variation in the depth H similar to that of the groove 96 according to the above-described embodiment. That is, the shape of the BB cross section of the groove portion 960A shown in Fig. 5 may be the same as that shown in Fig. 4, although not shown.

[0039] The first modified example also provides the same effect as the above-mentioned embodiment. That is, when the outer race 91A rotates relative to the case 2 as the vehicle moves forward, the oil pressure becomes higher at the center portion 961A than at the groove end portion 962A. In this way, the second modified example also allows each groove 96A to generate a wedge effect on the oil passing through the gap between the bearing 90A and the case 2 during rotation when the vehicle moves forward. This wedge effect makes it easier for the bearing 90A and the case 2 to be in a fluid lubrication state. As a result, wear of the case 2 caused by creep or the like can be reduced. In addition, according to the first modified example, since the center portion 961A is provided at two locations in the axial direction, the number of locations where the wedge effect occurs can be increased in the axial direction compared to the above-mentioned embodiment, and wear of the case 2 caused by creep or the like can be effectively reduced.

[0040] In the first modified example, the groove portion 960A of the groove 96A is open in the axial direction on the axial outer side, but is not limited to this. For example, the groove 96A may be in a form in which the axial outer side is closed (i.e., not open). In addition, the two groove portions 960A aligned in the axial direction may be separated from each other in the axial direction, but may be continuous. In addition, the two groove portions 960A aligned in the axial direction may be disposed at the same axial position, but may be disposed offset from each other in the axial direction.

[0041] FIG. 6 is an explanatory diagram of a groove 96B formed in the outer circumferential surface of an outer race 91B of a bearing 90B according to a second modified example, and is a diagram similar to the above-mentioned FIG.

[0042] The groove 96B of the bearing 90B according to the second modified example has a V-shaped shape in side view like the groove 96 according to the above-mentioned embodiment, but the central portion 961B is configured such that it is separated in the axial direction between the Y1 side and the Y2 side. In this way, the V-shaped groove 96B in side view may be discontinuous in the axial direction.

[0043] In the second modified example, the groove 96B may have a variation in the depth H similar to that of the groove 96 according to the above-described embodiment. That is, the shape of the CC cross section of the groove 96B shown in FIG. 6 may be the same as that shown in FIG.

[0044] The second modified example also provides the same effect as the above-mentioned embodiment. That is, when the outer race 91B rotates relative to the case 2 as the vehicle moves forward, the oil pressure becomes higher at the center portion 961B than at the groove end portion 962B. In this way, the second modified example also allows each groove 96B to generate a wedge effect on the oil passing through the gap between the bearing 90B and the case 2 during rotation when the vehicle moves forward. This wedge effect makes it easier for the bearing 90B and the case 2 to be in a fluid lubrication state. As a result, wear of the case 2 caused by creep or the like can be reduced. In addition, according to the second modified example, since the center portion 961B is provided at two locations along the axial direction, the number of locations where the wedge effect occurs can be increased in the axial direction compared to the above-mentioned embodiment, and wear of the case 2 caused by creep or the like can be effectively reduced.

[0045] In the second modified example, the groove 96B is open in the axial direction on the axial outer side, but is not limited to this. For example, the groove 96B may be in a form in which the axial outer side is closed (i.e., does not open).

[0046] Fig. 7 is an explanatory diagram of a groove 96C formed in the outer peripheral surface of an outer race 91C of a bearing 90C according to a third modified example, and is a diagram similar to the above-mentioned Fig. 3. Fig. 8 is an explanatory diagram of the inclination of the bottom of the groove 96C, and is a cross-sectional view taken along line DD in Fig. 7.

[0047] The groove 96C of the bearing 90C according to the third modified example has a circular outer shape in a side view and is in the form of a recess recessed radially inward. A plurality of grooves 96C are scattered. The plurality of grooves 96C may be arranged in a regular array pattern. Each of the plurality of grooves 96C has the same shape, but may have a plurality of types of shapes (for example, types with different sizes or depths). In the following, unless otherwise specified, one groove 96C will be described.

[0048] 8, the groove 96C has a central portion 961C and a peripheral portion 962C based on a circular outer shape in a side view. In the third modified example, the peripheral portion 962C is shallower than the central portion 961C.

[0049] In the third modified example, the center portion 961C of each groove 96C is located on the leading side in the rotation direction when the vehicle moves forward, compared to the peripheral portion 962C. Therefore, when the outer race 91C rotates relative to the case 2 as the vehicle moves forward, the oil pressure becomes higher in the peripheral portion 962C on the trailing side than in the peripheral portion 962C. That is, when the input shaft 31 rotates when the vehicle moves forward, the oil is drawn into the peripheral portion 962C in the narrow gap (see arrow R8), generating a relatively high oil pressure in the peripheral portion 962C on the trailing side. In this way, even in the third modified example, each groove 96C can generate a wedge effect on the oil passing through the gap between the bearing 90C and the case 2 during rotation when the vehicle moves forward. And, due to this wedge effect, the bearing 90C and the case 2 are more likely to be in a fluid lubrication state. As a result, wear of the case 2 caused by creep or the like can be reduced.

[0050] Fig. 9 is an explanatory diagram of a groove 96D according to a fourth modified example, which may be formed on the case 2D side. Fig. 9 shows, in a side view, a part of the inner circumferential surface of a part of the case 2D that faces the outer race 91 of the bearing 90 in the radial direction.

[0051] In the above-mentioned embodiment, the groove 96 is formed on the outer race 91 side. Instead of or in addition to this, as in the fourth modified example, the groove 96D may be formed on the case 2D. In this case, the groove 96D may only have a different shape from the above-mentioned groove 96 in a side view, and specifically, may have a shape in which a V-shape is inverted in the circumferential direction. That is, since the case 2D and the outer race 91 of the bearing 90 are in a relative rotating relationship, the inverted direction with respect to the rotation direction of the bearing 90 (arrow R30) is the rotation direction of the case 2D with respect to the bearing 90. In this case, with respect to the groove 96D, the groove end 962D is located on the leading side in the rotation direction of the bearing 90 when the vehicle moves forward, compared to the center side portion 961D. The depth (not shown) of the center side portion 961D is set smaller than the depth of the groove end 962D. Thereby, a wedge effect can be obtained based on the same principle as in the above-mentioned embodiment, and wear of the case 2D caused by creep or the like can be reduced.

[0052] Although each embodiment has been described above in detail, the present invention is not limited to the specific embodiment, and various modifications and changes are possible within the scope of the claims. In addition, it is also possible to combine all or a plurality of the components of the above-described embodiments.

[0053] For example, in the embodiment described above (as well as the first and second modified examples), the groove 96 has a V-shape in side view, but may extend linearly in the axial direction. In this case, too, each groove 96 can generate a wedge effect on the oil passing through the gap between the bearing and the case 2 during rotation when the vehicle moves forward, based on the same principle as that described above with reference to Fig. 8.

[0054] Also, in the above-described embodiment (and other modified examples, the same applies below), the outer race 91 is gap-fitted into the case 2, but this is not limited to the above. That is, in the above-described embodiment, the outer race 91 is gap-fitted into the case 2, but the inside-outside relationship may be reversed. That is, the inner race 92 may be gap-fitted into the fixed-side member. In this case, a groove similar to the above-described groove 96 may be formed in the inner circumferential surface of the inner race 92 (surface radially facing the fixed-side member) or the outer circumferential surface of the fixed-side member (surface radially facing the inner race 92).

[0055] In addition, in the embodiment described above, the outer race 91 is loosely fitted into the case 2, but this is not limited to the above. For example, the outer race 91 may be fitted into the case 2 in other ways, such as by intermediate fitting or interference fitting. In this case as well, a similar groove 96 may be formed in the outer race 91, thereby reducing wear on the case 2.

[0056] In the above-mentioned embodiment, the present invention is applied to a vehicle drive device that drives wheels, but the present invention can also be applied to a vehicle drive device that transmits driving force to vehicle components other than wheels, or to a drive device for purposes other than vehicles. For example, the present invention may be applied to a bearing structure for a rotating member that is drivingly connected to an actuator in a variable valve timing mechanism or an electric oil pump. Also, the applicable power transmission mechanism is arbitrary as described above, and the present invention may be applied to an AMT (Automated Manual Transmission). [Explanation of symbols]

[0057] 17 Vehicle drive device (drive device), 2, 2D Case (fixed side member), 90, 90A, 90B, 90C Bearing, 31 Input shaft (rotating side member), 96, 96A, 96B, 96C, 96D Groove, 961 Center side portion, 962 Groove end (axial end), 961C Center portion, 962C Peripheral portion

Claims

1. A fixed member; A rolling bearing; a rotating-side member that is drivingly connected to a driving source and is rotatably supported on the fixed-side member via the rolling bearing so as to be rotatable about an axis, the rolling bearing is press-fitted into one of the rotating-side member and the fixed-side member and fitted into the other of the rotating-side member and the fixed-side member; A groove capable of receiving oil is formed on a surface of the rolling bearing that faces the other member in a radial direction, or on a surface of the other member that faces the rolling bearing in a radial direction, A drive device, wherein the groove is formed so as to generate a wedge effect on oil flowing through the gap between the rolling bearing and the other member when the rotating member is rotating in one direction.

2. the groove extends in an axial direction along a rotation axis of the rotating member and in a circumferential direction around the axis, The drive unit according to claim 1 , wherein an axial end portion of the groove is deeper than a central portion axially inward of the end portion when viewed in a direction perpendicular to the rotation axis of the rotation-side member.

3. Mounted on the vehicle, The groove is formed on a surface of the rolling bearing, 3. The drive device according to claim 1, wherein the axial end portion of the groove is located on a leading side in a rotation direction of the rolling bearing when the vehicle moves forward, relative to the central portion.

4. The grooves are arranged in a plurality of pieces and each of the grooves has a central portion and a peripheral portion when viewed in a direction perpendicular to the rotation axis of the rotation-side member, The drive device according to claim 1 , wherein the peripheral portion has a depth shallower than that of the central portion.

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