POWER TRANSMISSION DEVICE

Abstract

A power transmission device (1) comprising: a first housing (5) comprising a first wall section (5W), a second housing (6) comprising a second wall section (6W) facing the first wall section (5W), a first rotating shaft (11) with an end section (11f) on which an external circumferential spline (11s) is formed, and which is supported by the first wall section (5W) via a bearing (14A) such that the external circumferential spline (11s) projects from the first wall section (5W) to the second wall section (6W), a second rotating shaft (15) which has a splined hole (15b) at an end section (15r) on which an internal circumferential splined connection (15s) is formed to engage with the external circumferential splined connection (11s), and which is supported by the second wall section (6W) via a bearing (14B) such that the internal circumferential splined connection (15s) projects from the second wall section (6W) to the first wall section (5W), and a connecting section (6D) which is provided on the first wall section (5W) and the second wall section (6W) such that it surrounds the outer circumferential splined gear (11s) and the inner circumferential splined gear (15s) and connects the first wall section (5W) and the second wall section (6W), wherein the power transmission device (1) is characterized in that a space surrounded by the first wall section (5W), the second wall section (6W) and the connecting section (6D), forming a connecting chamber (18) in which a wedge-tooth engagement section (17) is installed, in which the outer circumferential wedge toothing (11s) and the inner circumferential wedge toothing (15s) are engaged with each other, the first wall section (5W) includes an inlet opening (5a) which allows lubricating oil to flow from the interior of the first housing (5) into the connecting chamber (18), and the second wall section (6W) has an outlet opening (6a) which allows lubricating oil to flow out of the connecting chamber (18) into the second housing (6).

Description

[Technical field]

[0001] The present invention relates to a power transmission device. [Technical background]

[0002] JP 2005-201352 A discloses a known power transmission device in which shafts provided on separate housings are connected to each other and the housings are also connected to each other.

[0003] This power transmission device includes an output shaft contained in a front housing of a transmission, and a spline portion of the output shaft projects from a partition wall of the housing to a transfer.

[0004] A transmission housing includes an input shaft, and an input shaft spline bearing projects from a partition wall of the transmission housing toward the transmission.

[0005] The output shaft portion and the input shaft portion are installed in a space surrounded by the gearbox housing and the transmission housing. The output shaft portion and the input shaft portion are connected by a connecting shaft with splines formed on its inner circumference. Power is transmitted to the output shaft and the input shaft via the connecting shaft.

[0006] Patent Literature 2 discloses that a power transmission device includes a hollow shaft having a first end and a second end, a first shaft engaged with the first end of the hollow shaft, and a second shaft engaged with the second end of the hollow shaft. A discharge port is provided at the second end of the hollow shaft distal from the first shaft such that the discharge port forms an oblique angle with respect to the hollow shaft, and the discharge port is adapted to discharge a fluid therethrough.

[0007] Patent Literature 3 discloses a lubrication system adapted for the continuous lubrication of a loose spline joint, in which a collar is connected to a pair of shafts and axially spaced bearings that rotatably mount the collar and shafts in a closed housing. The collar is connected to the shafts via splines and includes a lubricant chamber between the spaced shaft ends, which is fed via an axial lubricant passage through a control port in one of the shafts. Upon rotation of the shafts and the collar, the lubricant entering the chamber is discharged by centrifugal force through a standpipe extending partially into the chamber from a collar wall, thereby flowing to the bearings.

[0008] Patent Literature 4 discloses an arrangement of a transmission and an add-on module, wherein the transmission has a drive shaft with a central first axial bore for the supply of lubricating oil and the add-on module has a connecting shaft mounted on the housing side via at least one rolling bearing, wherein the drive shaft and the connecting shaft are connected to one another in a rotationally fixed manner by a plug-in connection and wherein the lubricating oil supply to the plug-in connection and the at least one rolling bearing takes place via the central first axial bore of the drive shaft. [Citation list][Patent literature] [Patent Literature 1] JP 2005-201352 A [Patent Literature 2] US 2017 / 0114835 A1 [Patent Literature 3] US 4026386 A [Patent literature 4] DE 102011002904 A1 [Summary of the invention][Technical problem]

[0009] However, in the power transmission device disclosed in JP 2005-201352 A, lubricating oil suitable for lubricating the transmission component is contained in the casing of the transmission, and lubricating oil suitable for lubricating the transmission component is contained in the casing of the transmission.

[0010] These types of lubricating oil are contained independently in the gearbox housing and the transmission housing.

[0011] This requires separate management of the lubricating oil for the gearbox and transmission, and separate changes of the lubricating oil for the gearbox and transmission. As a result, the feasibility of a maintenance operation on the power transmission device may deteriorate.

[0012] The present invention has been made in view of the circumstances described above, and it is an object of the present invention to provide a power transmission device in which lubricating oil contained in a first case and a second case can be commonly used and the operability of a maintenance operation can be improved. [Solution to the problem]

[0013] The present invention is a power transmission device comprising: a first housing including a first wall portion, a second housing including a second wall portion facing the first wall portion, a first rotating shaft having an end portion on which an outer peripheral spline is formed and supported by the first wall portion via a bearing such that the outer peripheral spline projects from the first wall portion to the second wall portion, a second rotating shaft having a spline hole at one end portion on which an inner peripheral spline is formed to engage with the outer peripheral spline, and supported by the second wall portion via a bearing such that the inner peripheral spline projects from the second wall portion to the first wall portion, and a connecting portion,which is provided on the first wall portion and the second wall portion so as to surround the outer peripheral splines and the inner peripheral splines and connect the first wall portion and the second wall portion. The power transmission device is characterized in that a space surrounded by the first wall portion, the second wall portion, and the connecting portion forms a connecting chamber in which a spline engagement portion is installed, at which the outer peripheral splines and the inner peripheral splines are engaged with each other. The first wall portion includes an inflow opening that allows lubricating oil to flow into the connecting chamber from the interior of the first housing, and the second wall portion has an outflow opening that allows lubricating oil to flow out of the connecting chamber into the second housing. [Advantageous effect of the invention]

[0014] In this way, according to the present invention described above, lubricating oil contained in the first housing and the second housing can be commonly used, and the operability of a maintenance operation of the power transmission device can be improved. [Brief description of the drawings] [ Fig. 1] Fig. 1 is a view of a power transmission device according to an embodiment of the present invention as viewed from the diagonal left-rear side, showing a state in which a reduction gear case and a reduction gear cover are removed from a left case. [ Fig. 2] Fig. 2 is a view of the left case of the power transmission device according to the embodiment of the present invention, viewed from the diagonal right front side, with the upper portion of the left case being cut away. [ Fig. 3] Fig. 3 is a right side view of a reduction gear case of the power transmission device according to the embodiment of the present invention. [ Fig. 4] Fig. 4 is a left side view of a front portion of the power transmission device according to the embodiment of the present invention, showing a state in which a reduction gear cover is removed. [ Fig. 5] Fig. 5 is a left side view of a front portion of the power transmission device according to the embodiment of the present invention, showing a state in which the reduction gear cover and the reduction gear case are removed. [ Fig. 6] Fig. 6 is a cross-sectional view in a direction of arrows VI-VI in Fig. 3 considered. [ Fig. 7] Fig. 7 is a cross-sectional view in the direction of arrows VII-VII in Fig. 3 considered. [Description of the embodiment]

[0015] A power transmission device according to an embodiment of the present invention is a power transmission device comprising: a first housing including a first wall portion; a second housing including a second wall portion facing the first wall portion; a first rotation shaft having an end portion on which an outer peripheral spline is formed and supported by the first wall portion via a bearing such that the outer peripheral spline projects from the first wall portion to the second wall portion; a second rotation shaft having a spline hole at one end portion on which an inner peripheral spline is formed to engage with the outer peripheral spline, and supported by the second wall portion via a bearing such that the inner peripheral spline projects from the second wall portion to the first wall portion;and a connecting portion provided on the first wall portion and the second wall portion so as to surround the outer peripheral spline and the inner peripheral spline and connect the first wall portion and the second wall portion. A space surrounded by the first wall portion, the second wall portion, and the connecting portion forms a connecting chamber in which a spline engagement portion is installed, at which the outer peripheral spline and the inner peripheral spline are engaged with each other. The second wall portion includes a discharge port that allows lubricating oil to flow out of the connecting chamber into the second housing.

[0016] In this way, in the power transmission device according to the embodiment of the present invention described above, lubricating oil contained in the first housing and the second housing can be shared, and operability of a maintenance operation of the power transmission device can be improved. [Embodiment]

[0017] A power transmission device according to an embodiment of the present invention will be described with reference to the drawings.

[0018] The Fig. 1 to 7 show illustrations of the power transmission device according to an embodiment of the present invention. Fig. 1 to 7, up-down, front-back, and left-right directions are defined with respect to the power transmission device when it is installed in a vehicle, and the front-back direction of the vehicle is defined as the front-back direction, the left-right direction of the vehicle (the transverse direction of the vehicle) is defined as the left-right direction, and the up-down direction of the vehicle (the height direction of the vehicle) is defined as the up-down direction.

[0019] First, a configuration is described.

[0020] In Fig. 1, a transmission 1 is installed in an engine compartment (not shown) of a hybrid vehicle (hereinafter referred to simply as a vehicle), and an engine 2 as an internal combustion engine is connected to the transmission 1. The transmission 1 of the present embodiment constitutes a power transmission device of the present invention.

[0021] The transmission 1 is provided with a transmission case 3, and the transmission case 3 includes, in order from the engine 2 side, a right case 4, a left case 5, a reduction gear case 6, a reduction gear cover 7, and a parking cover 8. The individual cases and covers are coupled in the planes perpendicular to the left-right direction.

[0022] In other words, the mating surfaces of the individual housings and covers are formed in the planes perpendicular to the left-right direction.

[0023] The engine 2 is connected to the right housing 4. The engine 2 includes a crankshaft (not shown), and the crankshaft is installed to extend in the transverse direction of the vehicle (the left-right direction, hereinafter referred to simply as the vehicle transverse direction). The engine 2 of the present embodiment is constituted by a transverse engine, and the vehicle of the present embodiment is a front-engine, front-wheel drive (FF) vehicle.

[0024] The right casing 4 is a casing including a peripheral wall connected to the prime mover 2 at its right-side end portion, and a partition wall 4W installed in a bridge-like manner at the left-side end portion of the peripheral wall and having a shape open at its right side.

[0025] The left housing 5 is connected to the left-side end portion of the peripheral wall opposite the engine 2 with respect to the right housing 4. Thus, the left housing 5 is connected to the left side of the right housing 4. A flange portion 4A is formed on the outer periphery of the partition wall 4W of the right housing 4.

[0026] The left housing 5 is a housing including a peripheral wall connected to the right housing 4 at its left-side end portion, and a left side wall 5W installed in a bridge-like manner at the left-side end portion of the peripheral wall and having a shape open at its right side.

[0027] A flange portion 5A is formed at the right end portion of the peripheral wall of the left housing 5. The flange portion 4A is fixed to the flange portion 5A with a bolt (not shown), and the right housing 4 and the left housing 5 are connected to each other via the flange portions 4A and 5A.

[0028] A clutch (not shown) is contained in the interior of the right housing 4, which is located on the right side of the partition wall 4W. In the space surrounded by the partition wall 4W of the right housing 4 and the left side wall 5W of the left housing 5, ie inside the left housing 5 (see Fig. 2 and Fig. 6), a transmission chamber 9 is formed in which a plurality of rotary shafts for transmitting power from the prime mover 2 to a differential device (not shown) are contained.

[0029] A rotation shaft 11 of the plurality of rotation shafts is in the Fig. 2. The rotating shaft 11 is installed on the power transmission path between the engine 2 and the differential device and includes a plurality of transmission gears 11A and 11B and a synchronization device 12.

[0030] The transmission gears 11A and 11B are rotatable relative to the rotation shaft 11 and are in engagement with respective transmission gears (not shown) of another rotation shaft (not shown).

[0031] The synchronization device 12 is installed between the transmission gears 11A and 11B in the axial direction of the rotation shaft 11.

[0032] As in the Fig. 6, the synchronization device 12 includes a hub 12A, a sleeve 12B and synchronization rings 12C and 12D.

[0033] In the synchronizer 12, when the gear stage is shifted to a first gear stage (for example, a first gear stage) or a second gear stage (for example, a second gear stage) by the shifting operation, the sleeve 12B is moved by a shift fork (not shown) from a neutral position to the transmission gear 11A or the transmission gear 11B, and one of the transmission gear 11A and the transmission gear 11B is connected to the rotation shaft 11 via the synchronizer 12.

[0034] In this way, the power is transmitted to / from another rotating shaft meshing with the transmission gear 11A or the transmission gear 11B. Thus, the power of the prime mover 2 is transmitted to the differential device via the rotating shaft 11.

[0035] The differential device distributes the power of the prime mover 2 to left and right drive shafts (not shown) to transmit it to the drive wheels (not shown).

[0036] As in the Fig. 3 and Fig. 4, the reduction gear housing 6 includes a right side wall 6W, a peripheral wall 6A formed on the outer periphery of the right side wall 6W, and a disk-shaped motor mounting portion 6B provided on the upper portion of the right side wall 6W. As shown in Fig. 1, the reduction gear cover 7 includes a left side wall 7W and a peripheral wall 7A formed on the outer periphery of the left side wall 7W.

[0037] As in Fig. 6, the left side wall 7W of the reduction gear cover 7 is located opposite (left of) the left side wall 5W of the left housing 5 with respect to the right side wall 6W of the reduction gear housing 6 in the axial direction of the rotating shaft 11 and a rotating shaft 15, which will be described later. Thus, these walls are arranged in the order of the left side wall 7W of the reduction gear cover 7, the right side wall 6W of the reduction gear housing 6, and the left side wall 5W of the left housing 5 from the left side.

[0038] As in Fig. As shown in FIG. 1, the peripheral wall 7A of the reduction gear cover 7 is fixed to the peripheral wall 6A of the reduction gear case 6 by a plurality of bolts 10. Some of the bolts 10 are fixed from the reduction gear cover 7 through the reduction gear case 6 to the left side wall 5W, and the reduction gear case 6 and the reduction gear cover 7 are integrally attached to the left case 5.

[0039] As in Fig. 6, in the state where the reduction gear housing 6 is attached to the left housing 5, the right side wall 6W of the reduction gear housing 6 faces the left side wall 5W of the left housing 5. Thus, the left side wall 5W of the left housing 5 and the right side wall 6W of the reduction gear housing 6 face each other in the axial direction of the rotating shafts 11 and 15.

[0040] The left housing 5 of the present embodiment constitutes a first housing of the present invention, and the reduction gear housing 6 and the reduction gear cover 7 constitute a second housing of the present invention. The left side wall 5W of the left housing 5 constitutes a first wall portion of the present invention, and the right side wall 6W of the reduction gear housing 6 constitutes a second wall portion of the present invention. The rotation shaft 11 constitutes a first rotation shaft of the present invention, and the rotation shaft 15 constitutes a second rotation shaft of the present invention.

[0041] A travel motor (not shown) is mounted on the motor mounting portion 6B of the reduction gear case 6, and the motor is integrally fixed with the reduction gear case 6 and the reduction gear cover 7 to the left case 5.

[0042] As in Fig. 6, a bearing support portion 5B having a cylindrical shape is formed on the left side wall 5W of the left housing 5, and the bearing support portion 5B projects from the left side wall 5W of the left housing 5 to the inside of the left housing 5 (opposite the reduction gear housing 6).

[0043] A left end portion 11f of the rotating shaft 11 is rotatably supported by the bearing support portion 5B via a ball bearing 14A. The left end portion 11f of the rotating shaft 11 of the present embodiment constitutes one end portion of the first rotating shaft of the present invention, and the ball bearing 14A constitutes a bearing of the present invention.

[0044] A bearing support portion (not shown) is formed on the partition wall 4W of the right housing 4, and the bearing support portion projects from the partition wall 4W of the right housing 4 to the left side wall 5W of the left housing 5. A right end portion 11r of the rotating shaft 11 is rotatably supported by the bearing support portion (not shown) of the partition wall 4W via a ball bearing.

[0045] As in the Fig. 1, Fig. 5 and Fig. 6, an opening 5h is formed in the left side wall 5W of the left housing 5, and the opening 5h is open on the radially inner side of the bearing support portion 5B. As shown in Fig. 6, an outer peripheral spline 11s is formed on the left end portion 11f of the rotary shaft 11.

[0046] The outer peripheral spline 11s of the rotating shaft 11 protrudes from the left housing 5 (the gear chamber 9) to the right side wall 6W of the reduction gear housing 6 through the opening 5h. The outer peripheral spline 11s of the rotating shaft 11 is thus located outside the gear chamber 9 of the left housing 5.

[0047] In this way, the rotary shaft 11 is supported by the left side wall 5W of the left housing 5 via the ball bearing 14A such that the outer peripheral spline 11s projects from the left side wall 5W of the left housing 5 to the right side wall 6W of the reduction gear housing 6.

[0048] A reduction gear chamber 13 is formed in the space surrounded by the reduction gear case 6 and the reduction gear cover 7, that is, inside the reduction gear case 6 and the reduction gear cover 7, and the rotary shaft 15 and a chain 16 are contained in the reduction gear chamber 13.

[0049] The rotating shaft 15 is provided to bridge the reduction gear housing 6 and the reduction gear cover 7, with a right end portion 15r of the rotating shaft 15 being supported by the right side wall 6W of the reduction gear housing 6, and a left end portion 15f of the rotating shaft 15 being supported by the left side wall 7W of the reduction gear cover 7. The shaft length of the rotating shaft 15 is formed shorter than the shaft length of the rotating shaft 11. A sprocket 15A is provided on the outer peripheral portion of the rotating shaft 15, and the sprocket 15A rotates integrally with the rotating shaft 15.

[0050] As in the Fig. 4 and Fig. 6, a bearing support portion 6C is formed on the right side wall 6W of the reduction gear case 6, and the right end portion 15r of the rotating shaft 15 is rotatably supported by the bearing support portion 6C via a ball bearing 14B. The right end portion 15r of the rotating shaft 15 of the present embodiment constitutes one end portion of the second rotating shaft of the present invention, and the ball bearing 14B constitutes a bearing of the present invention.

[0051] As in Fig. 6, a bearing support portion 7B is formed on the left side wall 7W of the reduction gear cover 7, and the bearing support portion 7B projects from the left side wall 7W of the reduction gear cover 7 to the right side wall 6W of the reduction gear housing 6.

[0052] A left end portion 15f of the rotating shaft 15 is rotatably supported by the bearing support portion 7B via a ball bearing 14C. The left side wall 7W of the reduction gear cover 7 of the present embodiment constitutes a third wall portion of the present invention.

[0053] As the ball bearing 14A supporting the rotating shaft 11, a bearing larger than the ball bearings 14B and 14C supporting the rotating shaft 15 is used. The ball bearing 14A has a larger outer diameter than the ball bearings 14B and 14C, and an annular space between an inner ring and an outer ring of the ball bearing 14A (a space in which a rolling element and a cage are arranged) has a larger diameter than those of the ball bearings 14B and 14C.

[0054] The opening 5h of the left housing 5 is an opening having a substantially circular shape and is installed such that the opening 5h of the left side wall 5W of the left housing 5 has the same central axis as the central rotational axis of the ball bearings 14A, 14B and 14C and the central axes of the rotational shafts 11 and 15.

[0055] The inner diameter of the opening 5h of the left side wall 5W of the left housing 5, that is, the diameter of the opening 5h, is formed smaller than the outer diameter of the ball bearing 14B. Specifically, the diameter of the opening 5h is formed to be approximately equal to or smaller than the dimension of the outer ring shoulder diameter of the ball bearing 14B. Furthermore, the diameter of the opening 5h is formed to be approximately equal to or smaller than the dimension of the inner ring shoulder diameter of the ball bearing 14A.

[0056] As in the Fig. 3, Fig. 4 and Fig. As shown in Fig. 6, an opening 6h is formed in the right side wall 6W of the reduction gear housing 6, and the opening 6h is open on the radially inner side of the bearing support portion 6C. Specifically, the diameter of the opening 6h is formed to be approximately equal to or smaller than the outer diameter dimension of the outer ring of the ball bearing 14B. Furthermore, the diameter of the opening 6h is formed to be approximately equal to or smaller than the outer ring shoulder diameter dimension of the ball bearing 14B.

[0057] A through hole 15B is formed in the rotating shaft 15, and the through hole 15B penetrates in the axial direction of the rotating shaft 15. A spline hole 15b is formed at the right end portion 15r of the through hole 15B, and an inner peripheral spline 15s is formed in the spline hole 15b along the spline hole 15b.

[0058] The spline hole 15b is formed from the position of the left side surface of the ball bearing 14B to an open end 15c of the spline hole 15b in the axial direction of the rotary shaft 15.

[0059] The through hole 15B of the present embodiment extends from an open end 15d of the rotary shaft 15 on the left end portion 15f side to the open end 15c on the right end portion 15r side, and the portion of the through hole 15B in which the inner peripheral spline 15s is formed forms the spline hole 15b.

[0060] The open end 15c of the spline hole 15b is open in the area facing the left side wall 5W of the left case 5, and the open end 15d of the through hole 15B faces the left side wall 7W of the reduction gear cover 7.

[0061] The open end 15c, located at one end portion of the inner peripheral spline 15s of the rotating shaft 15, protrudes from the right side wall 6W of the reduction gear housing 6 to the left side wall 5W of the left housing 5 through the opening 6h. The inner peripheral spline 15s of the rotating shaft 15 is at least partially disposed in the opening 6h.

[0062] Thus, the rotary shaft 15 is supported by the right side wall 6W of the reduction gear housing 6 via the ball bearing 14B such that the inner peripheral spline 15s projects from the right side wall 6W of the reduction gear housing 6 to the left side wall 5W of the left housing 5.

[0063] The outer peripheral spline 11s of the rotating shaft 11 is inserted into the spline hole 15b of the rotating shaft 15, and the outer peripheral spline 11s of the rotating shaft 11 is engaged with the inner peripheral spline 15s of the rotating shaft 15.

[0064] In this way, the rotating shaft 15 rotates integrally with the rotating shaft 11. The outer peripheral spline 11s of the rotating shaft 11 and the inner peripheral spline 15s of the rotating shaft 15, which is engaged with the outer peripheral spline 11s, form a spline engagement portion 17.

[0065] The chain 16 is wound around the sprocket 15A of the rotating shaft 15 and a motor sprocket (not shown) attached to a motor shaft (not shown) of the motor. The power of the motor is transmitted from the motor sprocket to the rotating shaft 15 via the chain 16 and the sprocket 15A.

[0066] The engine power transmitted to the rotating shaft 15 is transmitted from the rotating shaft 15 to the differential device via the rotating shaft 11, and then transmitted to the left and right drive wheels via the left and right drive shafts. In this way, the vehicle is driven by the engine alone or by the engine and the prime mover 2 together.

[0067] On the other hand, at the time of vehicle deceleration, the power transmitted from the drive wheels to the differential device via the left and right drive shafts is transmitted from the rotating shaft 11 to the engine via the rotating shaft 15 and the chain 16. In this way, the engine performs power regeneration.

[0068] An external engagement portion 5C having a cylindrical shape is formed on the left side wall 5W of the left housing 5, and the external engagement portion 5C projects from the left side wall 5W of the left housing 5 to the right side wall 6W of the reduction gear housing 6.

[0069] An inner engagement portion 6D having a cylindrical shape is formed on the right side wall 6W of the reduction gear housing 6. The inner engagement portion 6D protrudes from the right side wall 6W of the reduction gear housing 6 to the left side wall 5W of the left housing 5 and engages with the inner peripheral surface of the outer engagement portion 5C.

[0070] The reduction gear housing 6 of the present embodiment is attached to the left housing 5 by connecting the right side wall 6W to the left side wall 5W of the left housing 5 via the external engagement portion 5C and the internal engagement portion 6D. The external engagement portion 5C and the internal engagement portion 6D of the present embodiment constitute a connecting portion of the present invention.

[0071] The outer engagement portion 5C and the inner engagement portion 6D surround the spline engagement portion 17, and the space surrounded by the outer engagement portion 5C, the inner engagement portion 6D, the left side wall 5W of the left housing 5 and the right side wall 6W of the reduction gear housing 6 forms a communication chamber 18 in which the spline engagement portion 17 is installed.

[0072] A sealing element (O-ring) 30 is provided between the inner engagement portion 6D and the outer engagement portion 5C to prevent the leakage of lubricating oil between the inner engagement portion 6D and the outer engagement portion 5C. Thus, the connecting chamber 18 is sealed from the exterior of the transmission housing 3 by the sealing element 30.

[0073] As in Fig. 2, a recess 5g is formed at an upper portion of the bearing support portion 5B, and the recess 5g enables communication between the interior of the bearing support portion 5B and the transmission chamber 9. Specifically, the recess 5g extends from the outside of the bearing support portion 5B to the outer ring of the ball bearing 14A, and the upper surface of the ball bearing 14A is exposed to the interior of the transmission chamber 9 through the recess 5g. Moreover, the recess 5g extends to a position closer to the right side wall 6W of the reduction gear housing 6 than the left side surface of the ball bearing 14A in the axial direction of the rotating shaft 11.

[0074] As in the Fig. 5 and Fig. 6, an inflow opening 5a is formed in the left side wall 5W of the left case 5, and the inflow opening 5a is formed at an upper portion of the opening 5h located above the rotating shafts 11 and 15.

[0075] The inflow port 5a is located at an end portion of the recess 5g on its left side (closer to the right side wall 6W of the reduction gear housing 6) in the axial direction of the rotating shaft 11, and is a portion of the recess 5g open to the communication chamber 18. Thus, the inflow port 5a communicates with the transmission chamber 9 and communicates with the communication chamber 18 via the recess 5g of the bearing support portion 5B. Thus, the transmission chamber 9 and the communication chamber 18 communicate with each other via the inflow port 5a.

[0076] As in Fig. 2, an oil groove 21 is installed in the left housing 5. The oil groove 21 includes a right-side oil groove 22 and a left-side oil groove 23. The right-side oil groove 22 includes a first oil groove portion 22A extending in the front-rear direction and a second oil groove portion 22B curved leftward from the front end of the first oil groove portion 22A and extending in the vehicle transverse direction.

[0077] The left-side oil groove 23 includes a first oil groove portion 23A extending to the left from a position overlapping and underlying the left end of the second oil groove portion 22B.

[0078] The left-side oil groove 23 includes a second oil groove portion 23B extending forward and downward from the left end of the first oil groove portion 23A. The distal end of the second oil groove portion 23B is arranged in its extension direction to face the inflow port 5a in the axial direction of the rotating shafts 11 and 15 and overlap the recess 5g in the up-down direction.

[0079] The first oil groove portion 22A is located in front of a final drive gear (not shown) of the differential device. Lubricating oil is stored at the bottom portion of the left case 5. The lubricating oil received by the final drive gear is introduced into the first oil groove portion 22A and flows from the first oil groove portion 22A to the second oil groove portion 22B.

[0080] The lubricating oil flowing into the second oil groove portion 22B is introduced into the first oil groove portion 23A of the left-side oil groove 23, flows from the first oil groove portion 23A to the second oil groove portion 23B, and is then guided from the second oil groove portion 23B through the recess 5g to the inflow port 5a.

[0081] The lubricating oil guided from the second oil groove portion 23B through the recess 5g to the inflow port 5a flows into the communication chamber 18 from the inflow port 5a. Thus, the lubricating oil received from the final driven gear flows into the recess 5g formed at an upper portion of the bearing support portion 5B through the oil groove 21 (the right-side oil groove 22 and the left-side oil groove 23), and the lubricating oil flowing into the recess 5g flows into the communication chamber 18 from the inflow port 5a open at an upper portion of the communication chamber 18.

[0082] As in Fig. 6, the open end 15c of the spline hole 15b of the rotating shaft 15 is located below the inflow port 5a, and the lubricating oil flowing from the inflow port 5a into the connecting chamber 18 (downward) falls on the open end 15c of the spline hole 15b and nearby portions of the rotating shaft 11. In this way, the lubricating oil is supplied into the spline hole 15b through the open end 15c.

[0083] As in Fig. 6, an oil passage 24 is provided at the open end 15d of the rotary shaft 15 on the side of the left end portion 15f facing the left side wall 7W of the reduction gear cover 7.

[0084] The oil passage 24 includes a disc portion 24A and a cylinder portion 24B. The disc portion 24A faces the left side wall 7W of the reduction gear cover 7 via a certain gap and is fixed to the reduction gear cover 7 by being interposed between the bearing support portion 7B and the ball bearing 14C in the axial direction of the rotating shafts 11 and 15.

[0085] The cylinder portion 24B is inserted into the through hole 15B and protrudes from the disk portion 24A toward the rotary shaft 11. The oil passage 24 of the present embodiment constitutes an oil supplying member of the present invention. In particular, as shown in Fig. As shown in Fig. 6, the lubricating oil flowing downward along the left side wall 7W of the reduction gear cover 7 can be collected in the gap between the left side wall 7W and the disc portion 24A by a recess formed at an upper portion of the bearing support portion 7B, and introduced into the through hole 15B through the cylinder portion 24B. The lubricating oil flowing into the through hole 15B is used to lubricate the spline engagement portion 17 and flows to the ball bearing 14C and is used for its lubrication.

[0086] An outlet opening 6a is formed in the right side wall 6W of the reduction gear housing 6 (see Fig. 3 and Fig. 4), and the discharge port 6a is formed in a lower portion of the bearing support portion 6C. The discharge port 6a enables communication between the communication chamber 18 and the reduction gear chamber 13, and the lubricating oil inside the communication chamber 18 flows into the reduction gear chamber 13 through the discharge port 6a. The discharge port 6a is formed by recessing a part of the bearing support portion 6C, and the lubricating oil flows through the outer diameter side of the ball bearing 14B and flows into the reduction gear chamber 13 from inside the communication chamber 18.

[0087] As in the Fig. 5 and Fig. 7, a return opening 5b is formed in the left side wall 5W of the left housing 5, and the return opening 5b enables communication between the communication chamber 18 and the transmission chamber 9 of the left housing 5. Specifically, the return opening 5b is formed at a lower portion of the left side wall 5W inside the external engagement portion 5C and in front of the opening 5h and enables communication between the communication chamber 18 and the transmission chamber 9 of the left housing 5. In addition, as shown in Fig. 2, a recess is formed in the bearing support portion 5B on the return port 5b side of the gear chamber 9, and the lubricating oil flows on the outside of the outer ring of the ball bearing 14A and returns to the gear chamber 9.

[0088] As in the Fig. 3, Fig. 4 and Fig. As shown in Fig. 7, a return port 6b is formed in the right side wall 6W of the reduction gear case 6, which faces (coincides with) the return port 5b in the axial direction of the rotating shafts 11 and 15. The return port 6b communicates between the communication chamber 18 and the reduction gear chamber 13. The return port 5b of the present embodiment constitutes a first case-side return port of the present invention, and the return port 6b constitutes a second case-side return port of the present invention. Note that a return chamber 26, which will be described later, is formed on the left case 5 side of the return port 6b.

[0089] As in Fig. 7, the return opening 6b faces the chain 16 in the axial direction of the rotating shafts 11 and 15 and extends diagonally forward and upward along the chain 16 from a lower position as shown in Fig. 4 shown.

[0090] As in the Fig. 3 and Fig. 6, a partition wall 6E is formed on the right side wall 6W of the reduction gear case 6, and the partition wall 6E protrudes from a wall surface 6w of the right side wall 6W (see Fig. 6) protrudes toward the left side wall 5W of the left housing 5. The protruding height of the partition wall 6E is approximately the same as that of the internal engagement portion 6D, and the partition wall 6E protrudes to a position near the left side wall 5W within the external engagement portion 5C. The distal end of the partition wall 6E on the left housing 5 side and the distal end of the internal engagement portion 6D on the left housing 5 side are subjected to cutting or grinding to ensure dimensional accuracy.

[0091] As in Fig. 3, the partition wall 6E includes a peripheral wall portion 6m disposed radially outside the opening 6h of the right side wall 6W and extending in the circumferential direction of the rotating shaft 11, and a vertical wall portion 6n extending upward from the upper end of the peripheral wall portion 6m and connected to the internal engagement portion 6D. The vertical wall portion 6n is located at the same height position as the inflow port 5a formed in the left side wall 5W of the left housing 5 and in front of the inflow port 5a. A lower portion of the peripheral wall portion 6m is connected to a protruding portion 6d protruding upward from the internal engagement portion 6D. The protruding portion 6d is provided at the same height position as the outflow port 6a and in front of the outflow port 6a.

[0092] As in the Fig. 5 and Fig. 6, a partition wall 5D is formed on the left side wall 5W of the left housing 5, and the partition wall 5D protrudes from a wall surface 5W of the left side wall 5W to the right side wall 6W of the reduction gear housing 6. The protruding height of the partition wall 5D is not as high as that of the partition wall 6E, the position of the distal end of the partition wall 5D is approximately the same as the position of the distal end of the internal engagement portion 6D inserted into the external engagement portion 5C, and protrudes to some extent from the left side wall 5W inside the external engagement portion 5C, and its distal end on the side of the reduction gear housing 6 is subjected to cutting or grinding to ensure dimensional accuracy.The partition wall 5D is formed to extend in the circumferential direction of the rotating shaft 11 and surround the opening 5h, and the inflow opening 5a is formed by recessing an upper portion of the partition wall 5D. In a region in front of the inflow opening 5a, the partition wall 5D extends upward from a portion extending in the circumferential direction of the rotating shaft 11.

[0093] The partition wall 5D faces the partition wall 6E of the right side wall 6W across a small gap in the axial direction of the rotating shafts 11 and 15. Thus, the portion of the partition wall 5D formed to surround the opening 5h and the peripheral wall portion 6m are arranged to face each other, and the portion of the partition wall 5D extending upward in a region in front of the intake port 5a and the vertical wall portion 6n are arranged to face each other. Note that the small gap between the partition wall 5D and the partition wall 6E is such a gap that lubricating oil cannot easily flow out, considering the viscosity of the lubricating oil.

[0094] As in the Fig. 3 and Fig. As shown in Figure 7, the connecting chamber 18 is divided by the partition wall 5D and the partition wall 6E into an inflow chamber 25, a return chamber 26 and a wave chamber 27.

[0095] The inflow chamber 25 communicates with the gear chamber 9 of the left housing 5 via the inflow opening 5a and communicates with the shaft chamber 27 via a connecting portion 25c. The shaft chamber 27 has the outflow opening 6a in its lower portion and communicates with the reduction gear chamber 13 via the outflow opening 6a. Thus, the gear chamber 9 and the reduction gear chamber 13 communicate with each other via the connecting chamber 18. Specifically, the gear chamber 9 and the reduction gear chamber 13 communicate with each other via the inflow chamber 25, and lubricating oil can be transferred between the gear chamber 9 and the reduction gear chamber 13 via the inflow chamber 25.

[0096] The return chamber 26 communicates with the gear chamber 9 via the return port 5b and with the reduction gear chamber 13 via the return port 6b. Thus, the gear chamber 9 and the reduction gear chamber 13 communicate with each other via the return chamber 26, and lubricating oil can be transferred between the gear chamber 9 and the reduction gear chamber 13 via the return chamber 26.

[0097] In this way, in the connecting chamber 18 of the present embodiment, two independent oil paths are formed by the inflow chamber 25, the shaft chamber 27 and the return chamber 26, which are divided by the partition walls 5D and 6E, in which lubricating oil is transferred between the gear chamber 9 and the reduction gear chamber 13. As shown in Fig. 3, viewed in the axial direction, the inflow chamber 25 is arranged in a range of substantially 90 degrees upward and rearward of the opening 6h, the wave chamber 27 is arranged in a range of substantially 90 degrees downward and rearward of the opening 6h and around the spline engagement portion 17, and the return chamber 26 is arranged in front of the opening 6h.

[0098] Since the interior space of the gear chamber 9 is formed at a lower position than the interior space of the reduction gear chamber 13, the amount of lubricating oil in the reduction gear chamber 13 at the time of parking or stopping the vehicle can be adjusted by the height position (specifically, the lower end position) of the return holes 5b and 6b. In the present embodiment, the return holes 5b and 6b are installed at such a height that the sprocket 15A and a lower portion of the chain 16 can immerse in the lubricating oil contained in the reduction gear chamber 13. Note that the lower end of the return hole 6b is located at a position lower than the lower end of the inner diameter of the outer ring of the ball bearing 14B.

[0099] Thus, the return port 5b and the return port 6b are communicated with each other via the return chamber 26, and the lubricating oil contained in the reduction gear chamber 13 is returned from the return port 5b through the return chamber 26 and the return port 6b into the gear chamber 9.

[0100] In this way, if the height position of the return holes 5b and 6b is lower than the lower end of the sprocket 15A, the lubricating oil contained in the reduction gear chamber 13 flows out into the gear chamber 9 when the vehicle is parked or stopped, and therefore the level of the lubricating oil contained in the reduction gear chamber 13 may become so low that the sprocket 15A and the chain 16 cannot be immersed in the lubricating oil, making it impossible to sufficiently lubricate the sprocket 15A and the chain 16 with the lubricating oil at the start of travel.

[0101] On the other hand, when the height position of the return ports 5b and 6b is set to a high position, the level of the lubricating oil contained in the reduction gear chamber 13 becomes so high that the movement resistance of the sprocket 15A and the chain 16 increases and the temperature of the lubricating oil rises unnecessarily, which accelerates its deterioration.

[0102] Therefore, in the present embodiment, the return holes 5b and 6b are installed at a height such that the sprocket 15A and the chain 16 can be sufficiently lubricated and the movement resistance of the sprocket 15A and the chain 16 does not increase. Specifically, they are formed at the same height position as a lower portion of the sprocket 15A.

[0103] As in the Fig. 3 and Fig. 6, the communication chamber 18 includes the shaft chamber 27. The shaft chamber 27 is a space containing the spline engagement portion 17 within the peripheral wall portion 6m of the partition wall 6E and is arranged to surround the outer peripheral portion of the spline engagement portion 17. The shaft chamber 27 communicates with the inflow chamber 25 via the communication portion 25c located rearward of the central axis of the spline engagement portion 17 to allow the inflow of lubricating oil. Furthermore, the shaft chamber 27 communicates with the reduction gear chamber 13 via the discharge port 6a located in its lower portion to allow the outflow of lubricating oil, and allows the inflow of lubricating oil from the inflow port 5a located in its upper portion.

[0104] As in Fig. 3, the peripheral wall portion 6m extends curvedly from a lower portion of the internal engagement portion 6D to the vertical wall portion 6n, and then extends curvedly from the vertical wall portion 6n to the central portion of the internal engagement portion 6D in the up-down direction, and extends in the circumferential direction within a range of approximately 270°. Thus, the peripheral wall portion 6m is arranged to surround the outer peripheral portion of the spline engagement portion 17, except for a portion from the connecting portion 25c to the exhaust port 6a on the rear lower side of the spline engagement portion 17.

[0105] As in Fig. 3, the connecting portion 25c is formed between the lower end of the peripheral wall portion 6m, which is located behind the shaft chamber 27 and at approximately the same height as a central portion 27a of the shaft chamber 27, and the internal engagement portion 6D, and the inflow chamber 25 communicates with the shaft chamber 27 via the connecting portion 25c.

[0106] The discharge port 6a is formed at the lowermost portion of the shaft chamber 27, and the connecting portion 25c communicates with the discharge port 6a via the shaft chamber 27. Thus, lubricating oil flowing from the inflow chamber 25 into the shaft chamber 27 via the connecting portion 25c flows downward along the inner surface of the internal engagement portion 6D and reaches the discharge port 6a to be supplied to the reduction gear chamber 13.

[0107] An upstream portion 25a of the inflow chamber 25 faces the inflow port 5a in the axial direction of the rotating shafts 11 and 15. A downstream portion 25b of the inflow chamber 25 communicates with the shaft chamber 27 via the connecting portion 25c. The words "upstream" and "downstream" herein refer to the upstream and downstream sides in the direction of the lubricating oil flowing from the inflow port 5a into the inflow chamber 25.

[0108] The wave chamber 27 is located below the inflow chamber 25 and communicates with the downstream portion 25b of the inflow chamber 25 via the connecting portion 25c.

[0109] Thus, the inflow chamber 25 extends from the upstream portion 25a facing the inflow port 5a to the connecting portion 25c located at the downstream portion 25b in the circumferential direction of the rotating shafts 11 and 15, and the lubricating oil flowing from the inflow port 5a to the inflow chamber 25 flows from the upstream portion 25a of the inflow chamber 25 to the downstream portion 25b and then flows into the shaft chamber 27 via the connecting portion 25c.

[0110] It should be noted that the rotation shafts 11 and 15 rotate from the upstream portion 25a relative to the inflow chamber 25 to the downstream portion 25b (in the Fig. 3 counterclockwise) when the vehicle moves forward, and rotate from the downstream section 25b relative to the inflow chamber 25 to the upstream section 25a (in the Fig. 3 clockwise) when the vehicle is reversing.

[0111] As in Fig. 3, the central portion 27a of the wave chamber 27 (the central portion of the partition wall 5D, the central portion of the peripheral wall portion 6m of the partition wall 6E) is decentered forward and downward from a central portion 6c of the inner engagement portion 6D (the central portion of the outer engagement portion 5C) to provide a space at the upper and front sides of the wave chamber 27, and the inflow chamber 25 and the return chamber 26 are arranged at the upper side of the wave chamber 27 and at the front side of the wave chamber 27, respectively, to provide a relatively large space within the limited diameter of the engagement portion. In addition, the cross-sectional area of ​​the passage of the inflow chamber 25 is formed smaller in the downstream portion 25b than in the upstream portion 25a.

[0112] A portion of the right side wall 6W at the inflow chamber 25 is lowered toward the left side wall 7W of the reduction gear cover 7 (toward the reduction gear chamber 13) via a portion of the right side wall 6W below the inflow chamber 25 (specifically, a portion of the right side wall 6W below the connecting portion 25c) in the axial direction of the rotating shafts 11 and 15. Thus, the internal space of the inflow chamber 25 is enlarged in the axial direction.

[0113] In other words, a portion of the right side wall 6W located below the connecting portion 25c bulges toward the left side wall 5W of the left housing 5 beyond a portion of the right side wall 6W closer to the upstream portion 25a of the inflow chamber 25 in the axial direction of the rotating shafts 11 and 15. This bulge extends continuously to the discharge port 6a, so that the discharge port 6a is spaced apart from the sprocket 15A and the chain 16, and the movement of the chain 16 or the like does not hinder the outflow of lubricating oil to the reduction gear chamber 13. It should be noted that the return opening 6b adjacent to the discharge opening 6a to the sprocket 15A and the chain 16 protrudes beyond the discharge opening 6a, so that lubricating oil can be guided into the return opening 6b by the movement of the chain 16 or the like.

[0114] Next, the operation will be described. The lubricating oil received by the final drive gear of the differential device is introduced into the first oil groove portion 22A of the right-side oil groove 22, and then introduced from the first oil groove portion 22A through the second oil groove portion 22B to the first oil groove portion 23A of the left-side oil groove 23.

[0115] The lubricating oil introduced into the first oil groove portion 23A is guided from the second oil groove portion 23B through the recess 5g to the inlet opening 5a.

[0116] The lubricating oil guided from the second oil groove section 23B through the recess 5g to the inlet opening 5a flows from the inlet opening 5a into the connecting chamber 18.

[0117] The lubricating oil flowing into the connecting chamber 18 from the inflow port 5a is divided by the flow force in the axial direction of the rotating shaft 15 into lubricating oil flowing into the upstream portion 25a of the inflow chamber 25 and lubricating oil flowing out into the shaft chamber 27. The lubricating oil flowing out into the shaft chamber 27 collides with the rotating shaft 11 and flows into the spline engagement portion 17 (through hole 15B) from the open end 15c to lubricate the spline. Furthermore, the lubricating oil flowing out into the shaft chamber 27 lubricates the ball bearings 14A and 14B, as described later.

[0118] The lubricating oil flowing into the upstream portion 25a of the inflow chamber 25 flows from the upstream portion 25a to the downstream portion 25b along the inflow chamber 25 and then flows into the shaft chamber 27 through the connecting portion 25c without being affected by the rotation of the rotating shafts 11 and 15 (rotation of the spline engagement portion 17) due to the presence of the peripheral wall portion 6m of the partition wall 6E.

[0119] The lubricating oil flowing from the inflow chamber 25 into the shaft chamber 27 flows along the inner surface of the internal engagement portion 6D, collides with the portion 6d projecting upward from the lower end of the internal engagement portion 6D to change its flow direction, and flows into the reduction gear chamber 13 by being discharged from the discharge port 6a into the reduction gear chamber 13. The lubricating oil flowing into the reduction gear chamber 13 lubricates the sprocket 15A, the chain 16, and the like.It should be noted that the lubricating oil flowing directly from the inflow port 5a into the shaft chamber 27 is carried or entrained by the rotation of the rotating shafts 11 and 15 (rotation of the spline engagement portion 17), adds an additional flow force to the lubricating oil flowing into the shaft chamber 27 from the inflow chamber 25, and collides with the protruding portion 6d together with the lubricating oil flowing into the shaft chamber 27 from the inflow chamber 25.

[0120] In the present embodiment, the inner diameter of the opening 5h of the left side wall 5W of the left housing 5 is formed smaller than the outer diameter of the ball bearing 14A. Furthermore, the opening 5h and the ball bearing 14A are formed and arranged to be coaxial. Thus, the height of the lower end of the opening 5h of the left side wall 5W is greater than the height of the lower end of the inner diameter of the outer ring of the ball bearing 14A.

[0121] In this way, the lubricating oil flowing into the shaft chamber 27 is blocked through the opening 5h of the left side wall 5W, and backflow into the gear chamber 9 is suppressed by the ball bearing 14A. It can be ensured that the lubricating oil flows into the reduction gear chamber 13 through the discharge opening 6a until the lubricating oil accumulates higher than the lower end of the opening 5h of the left side wall 5W.

[0122] The lubricating oil flowing into the shaft chamber 27 therefore flows more into the reduction gear chamber 13 than into the gear chamber 9. In this way, lubricating oil for lubricating the sprocket 15A and the chain 16 can be efficiently introduced into the reduction gear chamber 13.

[0123] Moreover, when a large amount of lubricating oil flowing into the shaft chamber 27 is accumulated, the lubricating oil flowing into the shaft chamber 27, although being carried or entrained by the spline engagement portion 17, thus increasing the movement resistance of the rotating shafts 11 and 15, collides with the protruding portion 6d upward from the internal engagement portion 6D to change its flow direction and is discharged from the discharge port 6a into the reduction gear chamber 13. Alternatively, after colliding with the protruding portion 6d to change its flow direction, the lubricating oil flows in the axial direction and is discharged from the communication chamber 18 of the ball bearings 14A and 14B.

[0124] Therefore, the entrainment or entrainment of lubricating oil to the downstream side in the rotational direction of the spline engagement portion 17 relative to the projecting portion 6d, ie, to the return chamber 26 in Fig. 3, is suppressed, and in this way, the amount of lubricating oil carried by the spline engagement portion 17 can be reduced overall, thereby reducing the movement resistance of the rotating shafts 11 and 15.

[0125] Furthermore, a large amount of lubricating oil carried or entrained by the spline engagement portion 17 forms a layer of a certain amount of oil, filling the space between the peripheral wall portion 6m and the rotating shafts 11 and 15. In this way, the lubricating oil flowing from the inflow port 5a to the spline engagement portion 17 can be reduced to increase the amount of lubricating oil flowing into the inflow chamber 25 and to increase the amount of lubricating oil flowing from the inflow chamber 25 into the shaft chamber 27.

[0126] On the other hand, part of the lubricating oil flowing from the inlet port 5a into the shaft chamber 27 is supplied into the spline hole 15b through the open end 15c of the spline hole 15b and flows into the reduction gear chamber 13 through the through hole 15B while lubricating the outer peripheral splines 11s of the rotating shaft 11 and the inner peripheral splines 15s of the rotating shaft 15.

[0127] The lubricating oil flowing from the inlet port 5a into the shaft chamber 27 flows to the left in the axial direction of the spline engagement portion 17 in the shaft chamber 27. The lubricating oil flowing to the left along the axial direction of the spline engagement portion 17 lubricates the ball bearing 14B and flows into the reduction gear chamber 13 through the ball bearing 14B.

[0128] In addition, the lubricating oil, which also flows out from the inflow port 5a and flows rightward in the axial direction of the spline engagement portion 17 in the shaft chamber 27, lubricates the ball bearing 14A while flowing into the gear chamber 9 through the ball bearing 14A.

[0129] On the other hand, the lubricating oil level in the reduction gear chamber 13 rises as the lubricating oil flows into the reduction gear chamber 13. The return port 6b is formed in the right side wall 6W of the reduction gear housing 6, and the return port 6b is formed in the return chamber 26 separated from the inflow chamber 25 by the partition wall 6E. The return port 6b faces the chain 16 in the axial direction of the rotating shaft 15 and extends in the up-down direction along the inner surface of the internal engagement portion 6D.

[0130] In this way, the lubricating oil carried or entrained by the chain 16 efficiently flows into the return opening 6b during the rotation of the chain 16. The lubricating oil flowing into the return opening 6b is returned from the return chamber 26 to the gear chamber 9 through the return opening 5b formed in the left side wall 5W of the left housing 5.

[0131] The return chamber 26 is separated from the shaft chamber 27 by the partition wall 6E, and the lubricating oil flowing into the return chamber 26 from the return port 6b is returned to the gear chamber 9 from the return port 5b without being affected by the rotation of the rotating shafts 11 and 15 (spline engagement portion 17).

[0132] Furthermore, since the case where lubricating oil flowing into the shaft chamber 27 collides with the portion 6d projecting upward from the internal engagement portion 6D and is carried or entrained relative to the projecting portion 6d toward the return chamber 26 is suppressed, the flow of lubricating oil from the return port 6b to the return port 5b through the return chamber 26 can be prevented from being obstructed by the flow of lubricating oil into the shaft chamber 27. In this way, the lubricating oil can be smoothly returned from the reduction gear chamber 13 to the gear chamber 9.

[0133] The gear chamber 9 has a larger volume than the reduction gear chamber 13 and contains a larger amount of lubricating oil than the amount of lubricating oil contained in the gear chamber 9. In this way, the lubricating oil heated in the reduction gear chamber 13 is returned from the reduction gear chamber 13 to the gear chamber 9 and cooled by the lubricating oil contained in the gear chamber 9.

[0134] Next, the effects of the transmission 1 of the present embodiment will be described.

[0135] The transmission 1 of the present embodiment includes the left housing 5 having the left side wall 5W, the reduction gear housing 6 having the right side wall 6W facing the left side wall 5W, and the rotary shaft 11 having the left end portion 11f on which the outer peripheral spline 11s is formed and supported by the left side wall 5W via the ball bearing 14A such that the outer peripheral spline 11s projects from the left side wall 5W to the right side wall 6W.

[0136] In addition, the transmission 1 includes the rotary shaft 15 having, at the right end portion 15r, the spline hole 15b on which the inner peripheral spline 15s meshing with the outer peripheral spline 11s is formed, and which is supported by the right side wall 6W via the ball bearing 14B such that the inner peripheral spline 15s projects from the right side wall 6W to the left side wall 5W.

[0137] Furthermore, the transmission 1 includes the outer peripheral engagement portion 5C and the inner peripheral engagement portion 6D provided on the left side wall 5W and the right side wall 6W to surround the outer peripheral splines 11s and the inner peripheral splines 15s, and to connect the left side wall 5W and the right side wall 6W.

[0138] The space surrounded by the left side wall 5W, the right side wall 6W, the outer engagement portion 5C and the inner engagement portion 6D forms the connecting chamber 18 in which the spline engagement portion 17 is installed, in which the outer peripheral splines 11s and the inner peripheral splines 15s are engaged.

[0139] The left side wall 5W of the left housing 5 has the inflow opening 5a, which allows lubricating oil to flow from the gear chamber 9 of the left housing 5 into the connecting chamber 18, and the right side wall 6W of the reduction gear housing 6 has the outflow opening 6a, which allows lubricating oil to flow from the connecting chamber 18 into the reduction gear housing 6.

[0140] In this way, the gear chamber 9 formed inside the left housing 5 can communicate with the communication chamber 18 through the inlet port 5a. Additionally, the reduction gear chamber 13 formed inside the reduction gear housing 6 and the reduction gear cover 7 can communicate with a lower portion of the communication chamber 18 through the outlet port 6a. Thus, the gear chamber 9 and the reduction gear chamber 13 communicate with each other via the communication chamber 18.

[0141] Therefore, the lubricating oil can be transmitted between the gear chamber 9 and the reduction gear chamber 13 through the connecting chamber 18, and the ball bearing 14A contained in the gear chamber 9, the ball bearings 14B and 14C contained in the reduction gear chamber 13, the sprocket 15A and the chain 16 can be lubricated with the same lubricating oil.

[0142] As a result, the need for individually controlling lubricating oil contained in separate cases as in a conventional technique can be eliminated, and the lubricating oil contained in the gear chamber 9 and the reduction gear chamber 13 can be changed at the same time in a single operation, so that the operability of a maintenance operation of the transmission 1 can be improved.

[0143] Moreover, according to the transmission 1 of the present embodiment, the left side wall 5W of the left housing 5 has the return port 5b allowing communication between the communication chamber 18 and the gear chamber 9 inside the left housing 5, and the right side wall 6W of the reduction gear housing 6 has the return port 6b allowing communication between the communication chamber 18 and the reduction gear chamber 13 inside the reduction gear housing 6 and the reduction gear cover 7, and the partition wall 6E protrudes from the wall surface 6w of the right side wall 6W to the left side wall 5W of the left housing 5.

[0144] The connecting chamber 18 is divided by the partition wall 6E into the inflow chamber 25 and the return chamber 26, and the inflow chamber 25 communicates with the gear chamber 9 via the inflow opening 5a and communicates with the reduction gear chamber 13 via the outflow opening 6a.

[0145] The return chamber 26 is connected to the gear chamber 9 via the return opening 5b and is connected to the reduction gear chamber 13 via the return opening 6b.

[0146] In this way, the gear chamber 9 and the reduction gear chamber 13 can communicate with each other via the inflow chamber 25, and the gear chamber 9 and the reduction gear chamber 13 can communicate with each other via the return chamber 26 separated from the inflow chamber 25.

[0147] In this way, lubricating oil can circulate between the gear chamber 9 and the reduction gear chamber 13, and the lubricating oil can be exchanged between the gear chamber 9 and the reduction gear chamber 13.

[0148] In the case where lubricating oil is contained independently in the gear chamber 9 and the reduction gear chamber 13 and the lubricating oil cannot circulate between the gear chamber 9 and the reduction gear chamber 13, it is necessary to adjust the amount of lubricating oil contained in the gear chamber 9 and the reduction gear chamber 13 in consideration of the lubricating property and the resistance to temperature rise of the lubricating oil.

[0149] Specifically, the reduction gear chamber 13 has a smaller volume than the gear chamber 9, and the amount of lubricating oil contained in the reduction gear chamber 13 is smaller than that contained in the gear chamber 9. Therefore, the lubricating oil contained in the reduction gear chamber 13 is relatively susceptible to temperature rise compared to the lubricating oil contained in the gear chamber 9, causing premature deterioration of the lubricating oil and reducing the durability of the lubricating oil. As a result, the lubricating property of the lubricating oil deteriorates.

[0150] It is necessary to increase the amount of lubricating oil contained in the reduction gear chamber 13 in order to suppress the temperature rise of the lubricating oil contained in the reduction gear chamber 13, but increasing the amount of lubricating oil increases the movement resistance of the sprocket 15A and the chain 16.

[0151] In the transmission 1 of the present embodiment, since lubricating oil can circulate between the gear chamber 9 and the reduction gear chamber 13 and the lubricating oil can be efficiently exchanged between the gear chamber 9 and the reduction gear chamber 13, lubricating oil returned from the reduction gear chamber 13 to the gear chamber 9 can be cooled with lubricating oil contained in the gear chamber 9.

[0152] In this way, the temperature rise of the lubricating oil can be suppressed, and premature deterioration of the lubricating oil and a reduction in its durability can be prevented. This can prevent the deterioration of the lubricating properties of the lubricating oil.

[0153] In addition, since the amount of lubricating oil contained in the reduction gear chamber 13 does not need to be increased, the movement resistance of the sprocket 15A and the chain 16 can be prevented from increasing.

[0154] In this way, in the transmission 1 of the present embodiment, the amount of lubricating oil contained in the transmission case 3 can be optimized.

[0155] Further, according to the transmission 1 of the present embodiment, the partition wall 5D and the partition wall 6E extend in the circumferential direction of the rotating shaft 11 to surround the spline engagement portion 17, and the communication chamber 18 has the shaft chamber 27 communicating with the inflow port 5a via the communication portion 25c between the inside of the partition wall 6E and the spline engagement portion 17.

[0156] In addition, the inflow port 5a faces the upstream portion 25a of the inflow chamber 25 in the axial direction of the rotating shaft 11, and a portion of the partition wall 5D below the inflow port 5a is recessed to communicate with the shaft chamber 27 located below the inflow port 5a.

[0157] In this way, lubricating oil flowing from the gear chamber 9 through the inlet opening 5a into the connecting chamber 18 can be distributed between the inlet chamber 25 and the shaft chamber 27.

[0158] In particular, when the amount of lubricating oil flowing into the connecting chamber 18 from the inflow port 5a is small, the spline engagement portion 17 can be lubricated by flowing lubricating oil from the inflow port 5a to be introduced into the shaft chamber 27, and the lubricating oil can flow from the shaft chamber 27 into the reduction gear chamber 13 through the outflow port 6a.

[0159] In addition, when the amount of lubricating oil flowing from the inflow port 5a into the connecting chamber 18 is large, by allowing lubricating oil to flow into the inflow chamber 25 and flow from the upstream portion 25a of the inflow chamber 25 to the downstream portion 25b, the lubricating oil can be controlled to flow from the connecting portion 25c into the reduction gear chamber 13 through the shaft chamber 27 and the outflow port 6a.

[0160] Further, according to the transmission 1 of the present embodiment, the inflow chamber 25 extends from the upstream portion 25a facing the inflow port 5a to the connecting portion 25c to the downstream portion 25b in the circumferential direction of the rotating shaft 11, and the cross-sectional area of ​​the passage of the inflow chamber 25 is smaller in the downstream portion 25b than in the upstream portion 25a.

[0161] In this way, the flow velocity of the lubricating oil in the inflow chamber 25 can be increased from the upstream portion 25a to the downstream portion 25b to allow the lubricating oil to flow from the connecting portion 25c into the shaft chamber 27, and the flow of the lubricating oil can be made more uniform. Furthermore, the connecting portion 25c is arranged behind the rotating shafts 11 and 15, and the lubricating oil flowing out of the connecting portion 25c can be suppressed from directly falling onto the rotating shafts 11 and 15.

[0162] In this way, a larger amount of lubricating oil can be led from the inflow chamber 25 through the outflow opening 6a into the reduction gear chamber 13.

[0163] Moreover, a portion of the right side wall 6W closer to the upstream portion 25a of the inflow chamber 25 is lowered to the left side wall 7W of the reduction gear cover 7 (to the reduction gear chamber 13) via a portion of the right side wall 6W closer to the downstream portion 25b of the inflow chamber 25 in the axial direction of the rotating shafts 11 and 15.

[0164] In this way, the volume on the downstream portion 25b side can be further reduced than the volume on the upstream portion 25a side of the inflow chamber 25, and the flow velocity of the lubricating oil in the inflow chamber 25 can be further increased from the upstream portion 25a to the downstream portion 25b.

[0165] Furthermore, in the present embodiment of the transmission 1, the spline hole 15b has the open end 15c facing the left side wall 5W, and the open end 15c is located below the inflow port 5a.

[0166] As a result, the lubricating oil guided from the oil groove 21 through the recess 5g to the inlet opening 5a can flow from the inlet opening 5a into the connecting chamber 18 and be supplied through the open end 15c of the spline hole 15b.

[0167] In this way, the outer peripheral splines 11s of the rotating shaft 11 and the inner peripheral splines 15s of the rotating shaft 15 can be lubricated by the lubricating oil, and the lubricating property of the spline engagement portion 17 can be improved. This can prevent the spline engagement portion 17 from being worn and improve the durability of the spline engagement portion 17.

[0168] Moreover, in the transmission 1 according to the present embodiment, the shaft length of the rotating shaft 15 is formed shorter than the shaft length of the rotating shaft 11. In addition, the rotating shaft 15 has the through hole 15B penetrating in the axial direction, and a portion of the through hole 15B on the left side wall 5W side forms the spline hole 15b in which the inner peripheral spline 15s is formed.

[0169] In this way, a portion of the through hole 15B penetrating the rotating shaft 15 in the axial direction can be formed as the spline hole 15b in which the inner peripheral spline 15s is formed. Thus, lubricating oil introduced into the spline hole 15b from the open end 15c of the rotating shaft 15 can be discharged from the open end 15d of the through hole 15B.

[0170] Therefore, the lubricating oil can be smoothly transferred to the spline hole 15b, and the lubricating property for the spline engagement portion 17 can be more effectively improved.

[0171] Moreover, according to the transmission 1 of the present embodiment, the reduction gear cover 7 has the left side wall 7W opposite to the left side wall 5W with respect to the right side wall 6W of the reduction gear case 6.

[0172] In addition, the rotary shaft 15 has the oil passage 24 which supplies lubricating oil to the through hole 15B at the open end 15d of the through hole 15B facing the left side wall 7W.

[0173] In this way, lubricating oil flowing along the left side wall 7W of the reduction gear cover 7 can be introduced into the through hole 15B through the oil passage 24.

[0174] Specifically, lubricating oil flowing along the left side wall 7W of the reduction gear cover 7 after being carried or entrained by the chain 16 and moving upward can be introduced into the space between the left side wall 7W and the disc portion 24A from a recess formed at an upper portion of the bearing support portion 7B, and introduced into the through hole 15B from the cylinder portion 24B.

[0175] In this way, the lubricating oil introduced into the through hole 15B can be supplied to the spline engagement portion 17 from both the open end 15d of the through hole 15B and the open end 15c of the spline hole 15b. This can more effectively improve the lubricating property of the spline engagement portion 17.

[0176] Furthermore, in the transmission 1 of the present embodiment, the partition wall 5D of the left side wall 5W of the left housing 5 and the partition wall 6E of the right side wall 6W of the reduction gear case 6 face each other across a small gap in the axial direction of the rotating shafts 11 and 15. This can prevent an obstacle when attaching the fastener of the reduction gear case 6 and the reduction gear cover 7 integrally to the left housing 5 with the bolts 10.

[0177] Particularly, in the case where the partition wall 5D and the partition wall 6E are in close contact, when the reduction gear case 6 and the reduction gear cover 7 are integrally fixed to the left housing 5 with the bolts 10, the reduction gear case 6 or the reduction gear cover 7 may be deformed to cause a problem due to, for example, the occurrence of a gap between the fixing portion of the reduction gear case 6 and the fixing portion of the left housing 5.

[0178] In contrast, in the case where the partition wall 5D and the partition wall 6E face each other with a small gap in the axial direction of the rotating shafts 11 and 15, the reduction gear housing 6 can be fixed to the left housing 5 with the fixing portion of the reduction gear housing 6 and the fixing portion of the left housing 5 in contact without any gap. Thus, assembly freedom can be provided and the assembly accuracy of the reduction gear housing 6 and the left housing 5 can be improved.

[0179] In addition, in a process of forming the external engagement portion 5C on the left side wall 5W of the left housing 5 with a cutting tool, the inner diameter of the external engagement portion 5C is machined by performing cutting from the side of the reduction gear housing 6, and the upper surface of the partition wall 5D (the surface facing the partition wall 6E) is machined with the same cutting tool.

[0180] Thus, the machining of the inner diameter of the outer engagement portion 5C and the machining of the upper surface of the partition wall 5D can be performed simultaneously in a single operation using the cutting tool. [List of reference symbols]

[0181] 1...gearbox (power transmission device), 5...left casing (first casing), 5a...inlet port, 5b...return port (first casing-side return port), 5W...left side wall (first wall section), 6...reduction gear casing (second casing), 6a...outlet port, 6b...return port (second casing-side return port), 6D. ...internal engagement portion (connecting portion), 6W...right side wall (second wall portion), 7...reduction gear cover (second case), 7W...left side wall (third wall portion), 11...rotation shaft (first rotation shaft), 11f...left end portion (end portion of the first rotation shaft), 11s...outer peripheral spline, 14A, 14B...ball bearing (bearing), 15...rotation shaft (second rotation shaft), 15B...through hole, 15b...spline hole, 15c...open end (open end of the spline hole), 15d...open end (open end of the through hole), 15r...right end portion (end portion of the second rotary shaft), 15s...inner peripheral spline, 17...spline engagement portion, 18...connecting chamber, 25...inflow chamber, 25a...upstream portion (upstream portion of the inflow chamber), 25b...downstream portion (downstream portion of the inflow chamber), 25c...connecting portion, 26...return chamber, 27...shaft chamber.

Claims

[1] A power transmission device (1) comprising: a first housing (5) comprising a first wall section (5W), a second housing (6) comprising a second wall portion (6W) facing the first wall portion (5W), a first rotary shaft (11) having an end portion (11f) on which an outer peripheral spline (11s) is formed, and which is supported by the first wall portion (5W) via a bearing (14A) such that the outer peripheral spline (11s) projects from the first wall portion (5W) to the second wall portion (6W), a second rotary shaft (15) having a spline hole (15b) at one end portion (15r) on which an inner peripheral spline (15s) is formed to engage with the outer peripheral spline (11s), and which is supported by the second wall portion (6W) via a bearing (14B) such that the inner peripheral spline (15s) projects from the second wall portion (6W) to the first wall portion (5W), and a connecting portion (6D) provided on the first wall portion (5W) and the second wall portion (6W) so as to surround the outer peripheral splines (11s) and the inner peripheral splines (15s) and connect the first wall portion (5W) and the second wall portion (6W), wherein the power transmission device (1) characterized by is that a space surrounded by the first wall portion (5W), the second wall portion (6W) and the connecting portion (6D) forms a connecting chamber (18) in which a spline engagement portion (17) is installed, at which the outer peripheral spline (11s) and the inner peripheral spline (15s) are engaged with each other, the first wall section (5W) comprises an inflow opening (5a) which allows lubricating oil to flow from the interior of the first housing (5) into the connecting chamber (18), and the second wall section (6W) has an outflow opening (6a) which allows lubricating oil to flow out of the connecting chamber (18) into the second housing (6). [2] The power transmission device (1) according to claim 1, wherein the first wall section (5W) has a first housing-side return opening (5b) which enables a connection between the connecting chamber (18) and an interior of the first housing (5), the second wall section (6W) has a second housing-side return opening (6b) which enables communication between the connection chamber (18) and an interior of the second housing (6), and a partition wall (6E) which projects from a wall surface (6w) of the second wall section (6W) to the first wall section (5W), the connecting chamber (18) is divided by the partition wall (6E) into an inflow chamber (25) and a return chamber (26), the inflow chamber (25) is connected to the interior of the first housing (5) via the inflow opening (5a) and is connected to the interior of the second housing (6) via the outflow opening (6a), and the return chamber (26) is connected to the interior of the first housing (5) via the first housing-side return opening (5b) and is connected to the interior of the second housing (6) via the second housing-side return opening (6b). [3] The power transmission device (1) according to claim 2, wherein the partition wall (6E) extends in a circumferential direction of the first rotary shaft (11) so as to surround the spline engagement portion (17), the connecting chamber (18) has a shaft chamber (27) which is connected to the inflow opening (5a) via a connecting portion (25c) between an inner side of the partition wall (6E) and an outer peripheral portion of the spline engagement portion (17), the inflow opening (5a) is located above the first rotary shaft (11) and faces an upstream portion (25a) of the inflow chamber (25) in an axial direction of the second rotary shaft (15), and the wave chamber (27) is located below the inlet opening (5a). [4] The power transmission device (1) according to claim 3, wherein the inflow chamber (25) extends from the upstream portion (25a) facing the inflow opening (5a) to the connecting portion (25c) via a downstream portion (25b) along a circumferential direction of the second rotary shaft (15), and a cross-sectional area of a passage of the inflow chamber (25) at the downstream portion (25b) is smaller than at the upstream portion (25a).

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