GEARBOX DEVICE

Abstract

The present disclosure provides a transmission device that can improve lubrication of a differential mechanism without using a pump. The present disclosure is a transmission device that includes a differential cage and a differential mechanism disposed within the differential cage. The differential mechanism includes first and second pinion gears and first and second side gears. The differential cage includes a housing, first and second sleeves connected to the housing, an oil discharge groove extending from an outer end of the first sleeve to the interior of the housing, and an oil introduction groove extending from an outer end of the second sleeve to the interior of the housing. The oil introduction groove is disposed such that the oil introduction groove reaches an interior of the housing on a radially outer side of the second side gear and does not overlap with either the first pinion gear or the second pinion gear.

Description

TECHNICAL FIELDThe present disclosure relates to a transmission device.BACKGROUND ARTIn a transmission device having a differential mechanism, a configuration is known in which lubricating oil is supplied to the differential mechanism by a pump (see Patent Document 1).CONVENTIONAL DOCUMENTSPATENT DOCUMENTSPatent Document 1: Japanese Unexamined Patent Application, Publication No. 2011-174582SUMMARY OF THE INVENTIONPROBLEMS TO BE SOLVED BY THE INVENTIONThe above-described transmission device requires a pump for supplying oil, thereby making a structure of the device complex. Moreover, the supply of oil could be hindered by the rotation of gears constituting the differential mechanism.In one aspect of the present disclosure, it is preferable to provide a transmission device that can improve lubrication of a differential mechanism without using a pump.MEANS FOR SOLVING THE PROBLEMSAn aspect of the present disclosure is a transmission device including a sun gear; a ring gear disposed concentrically with the sun gear; planetary gears meshed with the sun gear and the ring gear; a differential cage rotatably supporting the planetary gears; a differential mechanism disposed inside the differential cage; a first output shaft and a second output shaft connected to the differential mechanism; and a transmission case rotatably supporting the differential cage.The differential mechanism includes a first pinion gear and a second pinion gear having a respective rotation axis center perpendicular to a rotation axis center of the sun gear and facing each other; and a first side gear and a second side gear having a respective rotation axis center coincident with the rotation axis center of the sun gear and facing each other, wherein the first side gear meshes with the first pinion gear and the second pinion gear and is connected to the first output shaft, and the second side gear meshes with the first pinion gear and the second pinion gear and is connected to the second output shaft.The differential cage includes a housing in which the first pinion, the second pinion, the first side gear, and the second side gear are accommodated; a first sleeve that is connected to the housing and through which the first output shaft is inserted; a second sleeve that is connected to the housing and through which the second output shaft is inserted; at least one oil discharge groove that is provided on an inner circumferential surface of the first sleeve and extends from an outer end of the first sleeve to an inside of the housing; and at least one oil introduction groove that is provided on an inner circumferential surface of the second sleeve and extends from an outer end of the second sleeve to the inside of the housing.The at least one oil introduction groove is disposed such that the at least one oil introduction groove reaches an inner space of the housing at a radially outer side of the second side gear and, when viewed in the axial direction of the second side gear, overlaps neither the first pinion gear nor the second pinion gear.According to the above configuration, the oil introduction grooves and the oil discharge grooves constitute circulation paths for oil lubricating the differential mechanism inside the housing. In addition, the oil introduction grooves are arranged such that the oil introduction grooves do not overlap with the pinions, thereby reducing an obstruction to the supply of oil to the housing due to the rotation of the pinions. As a result, it is possible to improve the lubrication of the differential mechanism without using a pump.In an aspect of the present disclosure, the differential cage may include, as the at least one oil introduction groove, a first oil introduction groove and a second oil introduction groove that are arranged side by side between the first pinion gear and the second pinion gear in the circumferential direction of the second side gear. The second sleeve may include a first protrusion and a second protrusion protruding at the outer end of the second sleeve in the axial direction of the second side gear. The first protrusion and the second protrusion may be disposed such that the first oil insertion groove and the second oil insertion groove are disposed between the first protrusion and the second protrusion in the circumferential direction of the second side gear.According to the above configuration, in a case where the differential cage rotates relative to the second output shaft in the first direction (for example, in a case where a rotation speed of the second output shaft is greater than that of the differential cage), the first protrusion guides the oil into the first oil introduction groove, and in a case where the differential cage rotates relative to the second output shaft in a second direction opposite to the first direction (for example, in a case where the rotation speed of the second output shaft is less than that of the differential cage), the second protrusion guides the oil into the second oil introduction groove. This enables efficient supply of the oil to the differential mechanism regardless of speeds and rotational directions of the second output shaft.In an aspect of the present disclosure, the first oil introduction groove and the second oil introduction groove may each extend linearly and increase in width toward the housing. According to the above configuration, the oil introduction grooves are each linearly formed, thereby preventing changes in oil supply efficiency due to the rotational direction of the differential cage. Also, the width of the oil introduction grooves is each increased, thereby allowing the oil to be efficiently supplied to the differential mechanism by centrifugal force resulting from the rotation of the differential cage.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a schematic sectional view of a transmission device in an embodiment. FIG. 2 is a partially enlarged schematic sectional view of the transmission device of FIG. 1. FIG. 3 is a schematic perspective view of planetary gears and a differential cage in the transmission device of FIG. 1. FIG. 4 is a schematic perspective view of a portion of the differential cage of FIG. 3. FIG. 5 is a schematic rear view of a portion of the differential cage of FIG. 3. FIG. 6 is a schematic perspective view of a portion of a transmission housing in the transmission device of FIG. 1. FIG. 7 is a schematic cross-sectional view taken along line VII-VII of FIG. 1. FIG. 8 is a partially enlarged view of FIG. 2. FIG. 9A is a schematic diagram showing a state in which the differential cage relatively rotates in a first direction. FIG. 9B is a schematic diagram showing a state in which the differential cage relatively rotates in a second direction. FIG. 10 is a schematic front view of a portion of the differential cage of FIG. 3.EXPLANATION OF THE REFERENCE NUMERALS1... Transmission Device, 2... Sun gear, 3-ring gear, 4-planetary gears, 5--. Planetary gear bearing, 6... differential cage, 7... Differential mechanism, 8A... first output shaft, 8B... second output shaft, 9... Gear case, 10... motor shaft, 22... diameter-enlarged part, 23... communication holes, 61... case, 62... carrier, 63... Bearing holder, 64... first sleeve, 65A to 65D... Oil discharge grooves, 66... second sleeve, 67A to 67D...Öleinführnuten 71, and 72... Pinions, 73... pinion shafts, 74 and 75... side gears, 631... cylindrical members, 632... legs, 633... pockets, 661 and 662... protrusions, 911... protrusion, 912... inclined surface, 913... depression.MODE FOR CARRYING OUT THE INVENTIONHereinafter, embodiments to which the present disclosure is applied will be described with reference to the drawings.[1. First Embodiment][1-1. Configuration]A transmission device 1 shown in FIG. 1 is a device that is mounted in an automobile and transmits a driving force from a driving source of the automobile to a wheel thereof.The transmission device 1 includes a sun gear 2, a ring gear 3, planetary gears 4, planetary gear bearings 5, a differential cage 6, a differential mechanism 7, a first output shaft 8A, a second output shaft 8B, a transmission case 9, and a motor shaft 10.In the present embodiment, an axial direction of the sun gear 2 is an X axis, a vertical direction of the sun gear 2 is a Z axis, and a direction perpendicular to both the X axis and the Z axis is a Y axis.<>The motor shaft 10 is drivingly connected to a motor (not shown) and is axially rotated by driving force of the motor.<>The sun gear 2 constitutes a planetary gear mechanism (i.e., a speed reduction mechanism) together with the ring gear 3 and the planetary gears 4. The sun gear 2 is arranged outside the differential cage 6 and inside the transmission housing 9.The sun gear 2 is drivingly connected to the motor shaft 10 and is axially rotated by the driving force of the motor. A rotation axis center of the sun gear 2 is equal to a rotation axis center of the first output shaft 8A and the second output shaft 8B.The first output shaft 8A and the first sleeve 64 of the differential cage 6 are inserted through the sun gear 2. As shown in FIG. 2, the sun gear 2 includes a tooth part 21, a diameter-enlarged part 22, communication holes 23, and a connection part 24. FIG. 2 illustrates a state in which the planetary gear 4 is rotated downward from an upper position in FIG. 1.The toothed part 21 is an external toothing which is cylindrical and which meshes with the planetary gears 4. The first sleeve 64 of the differential cage 6 is inserted into the toothed part 21 in such a way that there is a small gap radially. In other words, the sun gear 2 overlaps with the first sleeve 64 in the radial direction of the sun gear 2, and an inner diameter of the gear part 21 is larger than an outer diameter of the first sleeve 64.The diameter-enlarged part 22 is a tubular portion that connects to the tooth part 21. The diameter-enlarged part 22 is connected to an end of the gear part 21 opposite to the differential mechanism 7. An inner diameter D 1 of the diameter-enlarged part 22 is larger than an inner diameter D 2 of an outer end 64A of the first sleeve 64. the first sleeve 64 is not inserted into the diameter-enlarged part 22. The inner diameter D 1 of the diameter-enlarged part 22 is larger than an outer diameter of a portion of the motor shaft 10 inserted into the connection part 24.The communication holes 23 each allow an opening in the outer end 64A of the first sleeve 64 to communicate with a space outside the sun gear 2. The communication holes 23 are spaced apart from each other in the circumferential direction of the diameter-enlarged part 22. In the present embodiment, four communication holes 23 are arranged at 90° apart from each other in the circumferential direction of the sun gear 2. However, the number of the communication holes 23 is not limited to four.The communication holes 23 allow lubricating oil discharged from the first sleeve 64 to be discharged by gravity or centrifugal force into a planetary gear accommodation space disposed between the differential cage 6 and the transmission case 9. The sun gear 2 serves as a gear constituting a planetary gear mechanism and a connecting member defining a circulation path for the lubricating oil in the present embodiment.The connecting part 24 is a tubular portion that connects to the diameter-enlarged part 22. The connecting part 24 is connected to an end of the diameter-enlarged part 22 opposite to the toothed part 21. As shown in FIG. 1, an end portion of the motor shaft 10 is longitudinally splined to the connecting member 24. An inner diameter of the connecting part 24 is smaller than that of the diameter-enlarged part 22.<Ring Wheel>The ring gear 3 is arranged concentrically with the sun gear 2. The ring gear 3 is fixed to an inner surface of the transmission case 9 and does not rotate with respect to the transmission case 9. The ring gear 3 is an internal toothing with which the planetary gears 4 mesh.<>The planetary gears 4 mesh with the sun gear 2 and the ring gear 3, respectively. the planetary gears 4 rotate the axis rotation center of the sun gear 2. in the present embodiment, three planetary gears 4 are arranged, but the number of the planetary gears 4 is not limited to three.The rotation axis center of each of the planetary gears 4 is parallel to the rotation axis center of the sun gear 2 (i.e., the X axis). The planet gears 4 are held by the differential cage 6. Each of the planetary gears 4 includes a first gear 41, a second gear 42, a first shaft 43, and a second shaft 44.The first toothed part 41 is an external toothing which meshes with the sun wheel 2. The second toothed part 42 is an external toothing which meshes with the ring gear 3. The outer diameter of the second gear 42 is smaller than that of the first gear 41. the second gear 42 is disposed closer to an opening end 9A of the transmission case 9 than the first gear 41.The first shaft 43 constitutes an end portion of each planetary gear 4 opposite to the opening end 9A. The first shaft 43 is supported by a carrier 62 of the differential cage 6. Specifically, the first shaft 43 is inserted through a ball bearing 5A held by the carrier 62.The second shaft 44 constitutes an end portion of each planetary gear 4 that is closer to the opening end 9A. The second shaft 44 is held by the differential cage 6. In particular, the second shaft 44 is inserted through a corresponding planetary gear bearing 5 which is held by a bearing holder 63 of the differential cage 6.< Storage>Through each of the planet gear bearings 5, a corresponding one of the second shafts 44 of the planet gears 4 is inserted. The planet gear bearings 5 are not particularly limited as long as the bearings can rotatably support the planet gears 4, but for example, known needle bearings are preferred.<Different Cage>The differential cage 6 rotatably supports the planetary gears 4 and houses the differential mechanism 7. The differential cage 6 is rotatably mounted on the transmission housing 9. While the planetary gears 4 are revolving, the differential cage 6 rotates around the rotation axis center of the sun gear 2.As shown in FIG. 2, the differential cage 6 includes a housing 61, the carrier 62, the bearing holders 63, the first sleeve 64, the oil discharge grooves 65A, 65B, 65C, 65D, a second sleeve 66, and oil introduction grooves 67A, 67B, 67C, 67D.FIG. 2 shows only the first oil discharge groove 65A and the third oil discharge groove 65C, and the second oil discharge groove 65B and the fourth oil discharge groove 65D are shown in FIG. 4. Similarly, FIG. 2 shows only the first oil introduction groove 67A and the third oil introduction groove 67C, and the second oil introduction groove 67B and the fourth oil introduction groove 67D are shown in FIG. 5.<>The housing 61 is a main body of the differential cage 6 and accommodates the differential mechanism 7. As shown in FIG. 1, the housing 61 is formed by connecting a first part 61A and a second part 61B in a direction parallel to the X axis.<Carrier>The carrier 62 is disposed such that the carrier 62 covers the housing 61 from a position of the transmission case 9 opposite to the opening end 9A (i.e., a position closer to the motor shaft 10). The bracket 62 is fixed to the housing 61 by a fixing member, for example, a bolt.< Holder>The bearing holders 63 each hold a corresponding one of the planetary gear bearings 5.The bearing holders 63 are spaced apart from each other in the circumferential direction of the housing 61 (i.e., the circumferential direction of the sun gear 2). The bearing holders 63 each include a cylindrical part 631, a leg 632, and a pocket 633.Each of the cylindrical parts 631 holds one of the planet gear bearings 5. The leg 632 extends radially outward from the outer circumferential surface of the housing 61 and connects the housing 61 to the cylindrical part 631.The pocket 633 of each bearing holder 63 protrudes from an end of the cylindrical part 631 opposite to the corresponding planetary gear 4. The pocket 633 is recessed from a radially inner side of the sun gear 2 to a radially outer side of the sun gear 2 (i.e., toward the direction away from the rotation axis center of the sun gear 2) to have an inner space. Also, each pocket 633 overlaps with the corresponding planetary gear bearing 5 in the axial direction of the sun gear 2.In other words, each pocket 633 includes a bottom wall intersecting the radial direction of the sun gear 2, two side walls intersecting the circumferential direction of the sun gear 2, and a front wall intersecting the X axis. The front wall in each pocket 633 covers a portion of the corresponding planetary gear bearing 5 and a portion of the corresponding cylindrical part 631 in the direction parallel to the X axis. The inner space in each pocket 633 allows liquid to enter from the radially inner side of the sun gear 2. The interior space in each pocket 633 communicates with a cavity in the cylindrical part 631.The bearing holders 63 are integral with the housing 61 and serve as a portion of the first part 61A. The cylindrical part 631 and the pocket 633 in each pocket 633 are integrated with each other. Each pocket 633 is simultaneously formed with a hole in the corresponding cylindrical part 631 when the first part 61A is machined. This makes it relatively easy to form the pockets 633 which are difficult to form by casting because of their small thickness.<First Sleeve>The first sleeve 64 shown in FIG. 1 is a tubular portion that is connected to the housing 61 and through which the first output shaft 8A is inserted.The first sleeve 64 extends from the housing 61 to the motor shaft 10 along the X axis. The first sleeve 64 allows an inner space of the housing 61 and an outer side of the housing 61 (specifically, an inner space in the sun gear 2) to communicate with each other.A portion of the first sleeve 64 is inserted into the sun gear 2. A center axis of the first sleeve 64 coincides with the rotation axis center of the sun gear 2. An inner diameter of the first sleeve 64 is smaller than a maximum inner diameter of the housing 61.<Oil Discharge Groove>As shown in FIG. 4, the first oil discharge groove 65A, the second oil discharge groove 65B, the third oil discharge groove 65C, and the fourth oil discharge groove 65D are provided on an inner circumferential surface of the first sleeve 64, and extend from the outer end 64A of the first sleeve 64 into the housing 61.The first oil discharge groove 65A, the second oil discharge groove 65B, the third oil discharge groove 65C, and the fourth oil discharge groove 65D are spaced apart from each other in the circumferential direction of the first sleeve 64. Details of the shapes of the oil discharge grooves 65A to 65D will be described below.<zwide sleeve>The second sleeve 66 shown in FIG. 1 is a tubular portion that is connected to the housing 61 and through which the second output shaft 8B is inserted.The second sleeve 66 extends from the housing 61 to the opening end 9A of the gear housing 9 along the X axis. The second sleeve 66 allows the inside of the housing 61 and the outside of the housing 61 (particularly, the inside of the gear case 9) to communicate with each other.The second sleeve 66 is inserted into a differential cage bearing 93. A center axis of the second sleeve 66 coincides with the rotation axis center of the sun gear 2. An inner diameter of the second sleeve 66 is smaller than the maximum inner diameter of the housing 61.As shown in FIG. 3, the second sleeve 66 includes a first protrusion 661 and a second protrusion 662. The first protrusion 661 and the second protrusion 662 each protrude relative to other positions at an outer end 66A of the second sleeve 66 in an axial direction of the second side gear 75 (i.e., along the X axis).One end of the first protrusion 661 in the circumferential direction of the second sleeve 66 is located at a position continuous to the first oil introduction groove 67A, and the other end is located at a position continuous to the third oil introduction groove 67C.In other words, the first protrusion 661 is located at the outer end 66A of the second sleeve 66 in a region between an end of the first oil introduction groove 67A and an end of the third oil introduction groove 67C. The first protrusion 661 provides a guide for guiding oil into the first oil introduction groove 67A and the third oil introduction groove 67C.The second protrusion 662 is in the form of the first protrusion 661 rotated 180° about the rotational axis center of the differential cage 6. One end of the second protrusion 662 in the circumferential direction of the second sleeve 66 is located at a position continuous to the second oil introduction groove 67B (see FIG. 5 ) and the other end is located at a position continuous to the fourth oil introduction groove 67D (see FIG. 5 ).In other words, the second protrusion 662 is located at the outer end 66A of the second sleeve 66 in a region between an end of the second oil introduction groove 67B and an end of the fourth oil introduction groove 67D. The second protrusion 662 provides a guide to guide oil into the second oil introduction groove 67B and the fourth oil introduction groove 67D.<Oil Insertion Groove>As shown in FIG. 5, the first oil introduction groove 67A, the second oil introduction groove 67B, the third oil introduction groove 67C, and the fourth oil introduction groove 67D are located on an inner circumferential surface of the second sleeve 66, and extend from the outer end 66A of the second sleeve 66 into the housing 61.The first oil introduction groove 67A, the second oil introduction groove 67B, the third oil introduction groove 67C, and the fourth oil introduction groove 67D are spaced apart from each other in the circumferential direction of the second sleeve 66. Details of the shapes of the oil introduction grooves 67A to 67D will be described below.<Differential Mechanism>The differential mechanism 7 illustrated in FIG. 1 is a known mechanism that distributes and transmits the rotation of the differential cage 6 to the first output shaft 8A and the second output shaft 8B while the first output shaft 8A and the second output shaft 8B are rotating at different speeds.The differential mechanism 7 includes a first pinion 71, a second pinion 72 (see FIG. 5 ), a pinion shaft 73, a first side gear 74, and the second side gear 75. Specifically, the first pinion 71, the second pinion 72, the pinion shaft 73, the first side gear 74, and the second side gear 75 are accommodated in the housing 61 of the differential cage 6.<Ritzel and Pinion Shaft>As shown in FIG. 5, the first pinion gear 71 and the second pinion gear 72 are each a bevel gear whose rotation axis center is perpendicular to the rotation axis center of the sun gear 2 (that is, the X axis).The axial rotation axis center of the first sprocket 71 and the rotation axis center of the second sprocket 72 coincide with each other. The first pinion 71 and the second pinion 72 are disposed opposite to each other. The first pinion 71 and the second pinion 72 have the same shape and are mirror images of each other.The pinion shaft 73 individually rotatably supports the first pinion 71 and the second pinion 72. A central axis (i.e., longitudinal direction) of the pinion shaft 73 is perpendicular to the X axis. The pinion shaft 73 is fixed to the housing 61 and does not rotate with respect to the differential cage 6. In other words, the pinion shaft 73 rotates together with the housing 61 around the rotation axis center of the sun gear 2.<Sidewheel>As shown in FIG. 1, the first side gear 74 and the second side gear 75 are each a bevel gear whose rotation axis center coincides with the rotation axis center of the sun gear 2 (that is, the X axis).The rotation axis center of the first side gear 74 and the rotation axis center of the second side gear 75 coincide with each other. The first side gear 74 and the second side gear 75 are disposed opposite to each other.The first side gear 74 is disposed closer to the motor shaft 10 along the X axis than the second side gear 75. the first side gear 74 and the second side gear 75 have the same shape and are mirror images of each other.The first side gear 74 and the second side gear 75 are rotatably supported on the housing 61, respectively. The first side gear 74 meshes with the first pinion 71 and the second pinion 72, and is connected to the first output shaft 8A. The second side gear 75 meshes with the first pinion 71 and the second pinion 72 and is connected to the second output shaft 8B.The first side gear 74 and the second side gear 75 rotate together with the differential cage 6, and at the same time also rotate relative to the differential cage 6 by rotation transmitted from the first pinion gear 71 and the second pinion gear 72.< Shaft>The first output shaft 8A and the second output shaft 8B are longitudinally splined to the first side gear 74 and the second side gear 75, respectively.The first output shaft 8A and the second output shaft 8B each rotate a wheel of an automobile. The first output shaft 8A and the second output shaft 8B rotate according to a rotational direction of the motor shaft 10 (i.e., the rotational direction of the differential cage 6) while rotating at different speeds through the differential mechanism 7 connected thereto.<>The transmission case 9 accommodates the sun gear 2, the ring gear 3 and the planetary gears 4 and rotatably supports the differential cage 6.The transmission case 9 includes a first body 91, a second body 92, the differential cage bearing 93, and an oil guide 94. the first body 91 and the second body 92 are connected to each other to thereby form the planetary gear accommodating space that accommodates the gears and the differential cage 6. Inside the second body 92, a motor (not shown) serving as a drive source is disposed.The first body 91 has the opening end 9A through which the second output shaft 8B is inserted. In the planetary gear accommodation space in the transmission case 9, lubricating oil for lubricating the gears and shafts is stored. The planetary gear accommodation space is sealed with a sealing member or the like.The differential cage bearing 93 rotatably supports the differential cage 6. In particular, the second sleeve 66 of the differential cage 6 is inserted through the differential cage bearing 93. The differential cage bearing 93 is supported by the first body 91. The differential cage bearing 93 is a shield bearing through which the lubricating oil supplied from the oil guide 94 can pass.The oil guide 94 shown in FIGS. 6 and 7 is a flow passage that has a groove-like shape and that is disposed in the planetary gear accommodating space. An inlet 941 of the oil guide 94 is disposed above the rotation axis center of the sun gear 2 and on a radially outer side relative to an orbit of the planetary gears 4. The inlet 941 is disposed at a position overlapping with the first tooth parts 41 of the planetary gears 4 in the radial direction of the sun gear 2.In FIG. 7, when the automobile moves forward, the sun gear 2 and the differential cage 6 rotate clockwise, and each planetary gear 4 rotates clockwise while rotating counterclockwise about its own axis. The direction of rotation of each component when the automobile moves backward is opposite to the direction in which the automobile moves forward.The lubricating oil stored in a lower portion of the planetary gear storage space is scooped up by the planetary revolving gear 4 and then drips into the inlet 941. This allows the lubricating oil to be supplied into the oil guide 94.An outlet 942 of the oil guide 94 is disposed below the inlet 941 and in the vicinity of the upper end of the outer end 66A of the second sleeve 66 of the differential cage 6 (see FIG. 1 ). The lubricating oil supplied from the inlet 941 of the oil guide 94 flows down inside the oil guide 94 and is supplied to the vicinity of the second sleeve 66.As shown by the arrow in FIG. 2, the lubricating oil that has been supplied to the vicinity of the second sleeve 66 passes through the second sleeve 66 and is supplied to the inside of the housing 61. This allows the lubrication of the differential mechanism 7. the lubricating oil inside the differential mechanism 7 passes through the first sleeve 64 and is discharged to the inside of the sun gear 2 (i.e., a connecting member).The lubricating oil discharged to the inside of the sun gear 2 is discharged from the communication holes 23 into the planetary gear accommodation space, and is then stored again in the lower portion of the planetary gear accommodation space. The lubricating oil stored in the planetary gear storage space is supplied to the oil guide 94 through the planetary gears 4 as described above. The lubricating oil is thus circulated in the transmission case 9.A part of the lubricating oil that has been supplied to the vicinity of the second sleeve 66 is not supplied to the housing 61 but passes through a shield of the differential cage bearing 93, and then flows downward below the second sleeve 66 and the housing 61 and is stored in the lower portion of the planetary gear storage space.<Feeding of Lubricating Oil to Planetary Gear Bearing>As shown in FIG. 8, a part of the lubricating oil is supplied to each planetary gear bearing 5 along an inner circumferential surface of the first body 91 of the transmission case 9. The flow of the lubricating oil will be described in detail below.The first body 91 of the gear case 9 includes a protrusion 911, an inclined surface 912, and a recess 913. The protrusion 911 is disposed to overlap with the pocket 633 of each bearing holder 63 from the radially inner side of the sun gear 2, and protrudes toward the planet gear bearings 5 in the axial direction of the sun gear 2.In other words, the protrusion 911 is a portion that protrudes from an inner surface of the first body 91 and covers a portion of an opening of each pocket 633. The protrusion 911 is disposed closer to the radially inner side of the sun gear 2 than a rotation axis L of each planetary gear 4 (i.e., a center axis of each planetary gear bearing 5).In the present embodiment, the protrusion 911 is formed annularly as viewed along the axial direction of the sun gear 2. In other words, the protrusion 911 is provided in the entire circumferential direction of the first body 91. However, the protrusion 911 may be provided only on the lower portion of the first body 91 (for example, a portion below the rotation axis center of the sun gear 2).The inclined surface 912 is inclined toward the protrusion 911 from a position farther from the planetary gear bearings 5 than the protrusion 911 in the axial direction of the sun gear 2 and located on an inner side relative to the protrusion 911 in the radial direction of the sun gear 2.In other words, the inclined surface 912 is formed of a portion of the inner surface of the first body 91 that extends from the protrusion 911 toward the opening end 9A. The inclined surface 912 may be formed of a flat surface, or may be curved or bent.The recess 913 is a portion that is disposed in a rear side of the protrusion 911 on the radially outer side of the sun gear 2 (i.e., a surface facing the inclined surface 912) and that is also recessed toward the radially inner side of the sun gear 2. The recess 913 is a groove extending along the circumferential direction of the sun gear 2. The recess 913 may be provided in the entire circumferential direction of the first body 91, or may be provided only at the lower portion of the first body 91 (for example, at a portion where the lubricating oil entering the recess 913 flows downward).As shown by an arrow in FIG. 8, the lubricating oil that passes through the shield of the differential cage bearing 93 via the oil guide 94 and flows down below the second sleeve 66, or the lubricating oil that does not pass through the oil guide 94 but directly reaches the inclined surface 912 because it is injected in the transmission case 9, moves along the inclined surface 912 toward the protrusion 911. The lubricating oil that has reached the protrusion 911 falls from the outer end thereof and is collected in the pocket 633.The lubricating oil that has moved from the outer end of the protrusion 911 to the rear side of the protrusion 911 is removed from the rear side of the protrusion 911 through the recess 913. Accordingly, the lubricating oil is prevented from flowing below the pocket 633 along the inner surface of the first body 91.< Of Oil Supply Groove and Oil Discharge Groove>As shown in FIG. 5, the oil introduction grooves 67A to 67D each reach the inside of the housing 61 at a radially outer side of the second side gear 75 relative to the second side gear 75 as viewed along an axial direction of the second side gear 75 (i.e., a direction parallel to the X axis). The discharge ends of the oil introduction grooves 67A to 67D have portions that do not overlap with the rotating second side gear 75, respectively.Further, the oil introduction grooves 67A to 67D are respectively disposed such that, when viewed along the axial direction of the second side gear 75, the oil introduction grooves 67A to 67D overlap neither the first sprocket 71 nor the second sprocket 72.The first oil introduction groove 67A and the second oil introduction groove 67B are disposed side by side between the first sprocket 71 and the second sprocket 72 in the circumferential direction of the second side gear 75. The shape of the second oil introduction groove 67B is symmetrical to that of the first oil introduction groove 67A with respect to a virtual plane perpendicular to the Y axis.The shape of each of the third oil introduction groove 67C and the fourth oil introduction groove 67D is symmetrical with the shape of the first oil introduction groove 67A or the second oil introduction groove 67B with respect to a virtual plane perpendicular to the Z axis. That is, the third oil introduction groove 67C and the fourth oil introduction groove 67D are arranged opposite to each other via the pinion shaft 73, the first oil introduction groove 67A, and the second oil introduction groove 67B, and are arranged side by side between the first pinion gear 71 and the second pinion gear 72 in the circumferential direction of the second side gear 75.The oil introduction grooves 67A to 67D extend linearly, respectively. In other words, a line connecting the centers of each of the oil introduction grooves 67A to 67D in the width direction thereof is a straight line. Further, the width of the oil introduction grooves 67A to 67D increases toward the housing 61, respectively. In other words, the width of each of the oil introduction grooves 67A to 67D is minimum at the outer end 66A of the second sleeve 66, and is maximum inside the housing 61.As shown in FIGS. 9A and 9B, the first oil introduction groove 67A and the second oil introduction groove 67B are disposed between the first protrusion 661 and the second protrusion 662 of the second sleeve 66 in the circumferential direction of the second side gear 75 (i.e., in the circumferential direction of the second sleeve 66), and also the third oil introduction groove 67C and the fourth oil introduction groove are disposed in the other region between the first oil introduction groove 67A and the second oil introduction groove 67B.Specifically, ends of each of the first oil introduction groove 67A and the second oil introduction groove 67B are disposed in a region between a first end portion 661A of the first protrusion 661 and a first end portion 662A of the second protrusion 662. Ends of each of the third oil introduction groove 67C and the fourth oil introduction groove 67D are disposed in a region between a second end portion 661B of the first protrusion 661 and a second end portion 662B of the second protrusion 662.As shown in FIG. 9A, when the differential cage 6 rotates relative to the second output shaft 8B, the lubricating oil O in the planetary gear accommodation space hits the first end portion 661A of the first protrusion 661 and is guided into the first oil introduction groove 67A. Alternatively, the lubricating oil O hits the second end portion 662B of the second protrusion 662 and is guided into the fourth oil introduction groove 67D.As shown in FIG. 9B, when the differential cage 6 rotates relative to the second output shaft 8B in a second direction R 2 opposite to the first direction R 1, the lubricating oil O in the planetary gear accommodation space hits the second end portion 661B of the first protrusion 661 and is guided into the third oil introduction groove 67C. Alternatively, the lubricating oil O hits the first end portion 662A of the second protrusion 662 and is guided into the second oil introduction groove 67B.As shown in FIG. 10, the oil discharge grooves 65A to 65D each reach the inside of the housing 61 on a radially outer side of the first side gear 74 relative to the first side gear 74, as viewed in an axial direction of the first side gear 74 (i.e., the direction parallel to the X axis). The outlet ends of the oil discharge grooves 65A to 65D have portions that do not overlap with the first rotating side gear 74, respectively.FIG. 10 is a diagram from the inside of the housing 61 when viewed from the second sleeve 66. the first pinion 71, the second pinion 72, the pinion shaft 73, and the second side gear 75 are omitted in FIG. 10.The oil discharge grooves 65A to 65D are each disposed at a position overlapping with the first sprocket 71 or the second sprocket 72 when viewed along the axial direction of the first side gear 74. Further, the oil discharge grooves 65A to 65D are respectively disposed between any two of the oil introduction grooves 67A to 67D in the circumferential direction of the first side gear 74, as viewed along the axial direction of the first side gear 74.As shown in FIG. 4, the oil discharge grooves 65A to 65D extend linearly, respectively. Further, the width of the oil discharge grooves 65A to 65D increases toward the outer end 64A to the first sleeve 64, respectively. In other words, the width of each of the oil introduction grooves 67A to 67D is minimum at the housing 61 and is maximum at the inner side than at the outer end 64A of the first sleeve 64.[1-2. Effects]According to the embodiments described above in detail, the following effects can be obtained.(1a) The oil introduction grooves 67A to 67D and the oil discharge grooves 65A to 65D constitute circulation paths for oil lubricating the differential mechanism 7 inside the housing 61. Also, the oil introduction grooves 67A to 67D are arranged such that the oil introduction grooves 67A to 67D do not overlap with the pinions 71, 72, thereby reducing an obstruction of the supply of oil to the housing 61 due to the rotation of the pinions 71, 72. As a result, it is possible to improve the lubrication of the differential mechanism 7 without using a pump.(1b) In a case where the differential cage 6 rotates relative to the second output shaft 8B in the first direction R 1 (for example, in a case where a rotational speed of the second output shaft 8B is greater than that of the differential cage 6), the first protrusion 661 introduces the oil into the first oil introduction groove 67A, and in a case where the differential cage 6 rotates relative to the second output shaft 8B in the second direction R 2 (for example, in a case where the rotational speed of the second output shaft 8B is less than that of the differential cage 6), the second protrusion 662 introduces the oil into the second oil introduction groove 67B. This allows the oil to be efficiently supplied to the differential mechanism 7 regardless of the speeds and rotational directions of the second output shaft 8B.(1c) The oil introduction grooves 67A to 67D are each linearly formed, thereby preventing changes in the oil supply efficiency due to the rotational direction of the differential cage 6. Also, the width of the oil introduction grooves 67A to 67D each increases, thereby allowing the oil to be efficiently supplied to the differential mechanism 7 by the centrifugal force resulting from the rotation of the differential cage 6.[2. Other Embodiments]Although the embodiment of the present disclosure has been described above, it is to be understood that the present disclosure is not limited to the embodiment described above, but may be implemented in various forms.(2a) In the transmission device of the above-described embodiment, the second sleeve may not necessarily include the first protrusion or the second protrusion.(2b) In the transmission device of the above-described embodiment, the oil introduction groove may not necessarily be linearly shaped. For example, the oil introduction groove may be spiral. Further, the width of the oil introduction groove does not necessarily increase toward the housing. For example, the width of the oil introduction groove may be constant along its longitudinal direction.(2c) In the transmission device of the above-described embodiment, the number of oil introduction grooves and the number of oil discharge grooves are not limited to four, respectively. For example, the number of oil introduction grooves and the number of oil discharge grooves are not limited to the number equal to or less than three (including one).(2d) Two or more functions of one component in the above-described embodiments may be distributed to two or more components, or the functions of two or more components may be integrated into a single component. Also, a portion of the configurations of the embodiments may be omitted. At least a portion of the configurations of the embodiments may be added or replaced with them. Note that any form included in the technical idea defined by the wording of the appended claims may be an embodiment of the present disclosure.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedJP 2011-174582

[0003]

Claims

A transmission device, comprising: a sun gear; an annular gear concentrically arranged with the sun gear; planetary gears meshed with the sun gear and with the annular gear; a differential cage rotatably supporting the planetary gears; a differential mechanism disposed within the differential cage; a first output shaft and a second output shaft connected to the differential mechanism; and a transmission case rotatably supporting the differential cage, wherein the differential mechanism includes: a first pinion and a second pinion whose respective rotation axis center is perpendicular to a rotation axis center of the sun gear and which face each other; and a first side gear and a second side gear, each rotation axis center of which coincides with the rotation axis center of the sun gear and which faces each other, the first side gear meshing with the first pinion and the second pinion and being connected to the first output shaft, and the second side gear meshing with the first pinion and the second pinion and being connected to the second output shaft, the differential cage including: a housing in which the first pinion, the second pinion, the first side gear, and the second side gear are accommodated; a first sleeve, which is connected to the housing and through which the first output shaft is inserted; a second sleeve, which is connected to the housing and through which the second output shaft is inserted; at least one oil discharge groove provided on an inner circumferential surface of the first sleeve and extending from an outer end of the first sleeve to an inside of the housing; and at least one oil introduction groove provided on an inner circumferential surface of the second sleeve and extending from an outer end of the second sleeve to the inside of the housing, and the at least one oil introduction groove is disposed such that the at least one oil introduction groove reaches an inner space of the housing on a radially outer side of the second side gear, and, when viewed in the axial direction of the second side gear, overlaps neither the first pinion nor the second pinion.The transmission device according to claim 1, wherein the differential cage includes, as the at least one oil introduction groove, a first oil introduction groove and a second oil introduction groove that are arranged side by side between the first pinion gear and the second pinion gear in the circumferential direction of the second side gear, the second sleeve includes a first protrusion and a second protrusion that protrude at the outer end of the second sleeve in the axial direction of the second side gear, and the first protrusion and the second protrusion are arranged such that the first oil introduction groove and the second oil introduction groove are arranged between the first protrusion and the second protrusion in the circumferential direction of the second side gear.The transmission device according to claim 2, wherein the first oil introduction groove and the second oil introduction groove each extend linearly and increase in width toward the housing.

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