Vehicle drive transmission device

Abstract

A main case (1) comprises: a specific facing surface (15) which faces, in a radial direction (R), a first side surrounding part (51) of a differential case (40) that surrounds a first side protrusion part (5) disposed so as to protrude toward an axial first side (L1) with respect to a differential input gear (G34) in a differential gear mechanism (44), and which is formed so as to surround the first side surrounding part (51) from a lower side (V2); and a side wall surface (17) which is formed so as to extend toward a radial inside (R1) from an end section on the axial first side (L1) of the specific facing surface (15). An oil storage part (7) in which oil is stored is formed in a space (E) surrounded by the specific facing surface (15), the side wall surface (17) and a surface (49) facing the axial first side (L1) of the differential input gear (G34).

Description

[Technical Field]

[0001] The present invention relates to a vehicle drive transmission device that includes a differential gear unit and a main case that houses the differential gear unit and oil therein. [Background technology]

[0002] Japanese Patent Application Laid-Open Publication No. 2015-178887 discloses a differential gear device (1) in which oil is contained within a case (2) that houses a differential gear mechanism (reference numerals in parentheses in the Background Art section refer to those of the referenced document). The case (2) houses a differential input gear (12) that inputs driving force to the differential gear mechanism and a differential case (10) that rotates integrally with the differential input gear (12). The differential case (10) houses a pinion gear (15), a pinion shaft (14), and a pair of side gears (18, 19). The differential case (10) has an opening that communicates between the inside and outside of the differential case (10). Lubricating oil is supplied through the opening to gears, gear support members, and other components to be lubricated housed within the differential case (10). Specifically, the differential input gear (12) scoops up the oil stored in the case (2), and the lubricating oil is supplied into the differential case (10) through the opening.

[0003] In this structure, if the oil level inside the case (2) is high while the differential input gear (12) is rotating, the agitation resistance caused by the differential input gear (12) stirring up the oil increases, resulting in a large loss of power transmission in the differential gear device (1). Therefore, in the differential gear device (1) disclosed in the above-mentioned document, a baffle plate (30) is disposed inside the case (2). The space inside the case (2) is divided into a first chamber (C1) in which the differential input gear (12) is disposed and a second chamber (C2) located on the opposite side of the differential input gear (12) from the differential input gear (12) across the baffle plate (30). Some of the oil stirred up by the differential input gear (12) is stored in the second chamber (C2), lowering the oil level stirred up by the differential input gear (12), thereby reducing the agitation resistance of the differential input gear (12). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-178887 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when a differential gear unit starts rotating from a stopped state, it takes a certain amount of time for the oil scooped up to reach the lubrication target components in the differential case. In other words, at the beginning of rotation, there is a possibility that the gears and gear support members housed in the differential case will not be supplied with enough oil. For example, if a baffle plate is provided, as in the differential gear unit disclosed in the above-mentioned document, the amount of oil at the beginning of rotation can be increased, potentially increasing the amount of oil scooped up by the differential input gears and supplying more oil to the differential case more quickly. However, providing a baffle plate increases the cost of the device due to the cost of the baffle plate itself and the assembly cost of assembling it.

[0006] In view of the above background, it is desirable to realize a vehicle drive transmission device that can properly supply lubricating oil to the differential case containing the differential gear mechanism, even at the beginning of rotation when the differential input gear that transmits driving force to the differential gear mechanism begins to rotate from a stationary state, without providing a baffle plate. [Means for solving the problem]

[0007] In view of the above-mentioned problems, a vehicle drive transmission device is provided which includes a differential gear device and a main case which houses the differential gear device and oil therein, wherein the differential gear device includes differential input gears to which driving force from a drive source for wheels is transmitted, a differential gear mechanism which distributes the driving force transmitted to the differential input gears to a pair of output members which are drivingly connected to a pair of the wheels, respectively, and a differential case which is connected to the differential input gears so as to rotate integrally with the differential input gears and which contains the differential gear mechanism, the differential case having an opening which connects the inside where the differential gear mechanism is disposed to the outside, the direction along the rotation axis of the differential input gears being an axial direction, the direction perpendicular to the rotation axis being a radial direction, one side in the axial direction being an axial first side, and the differential gear mechanism is connected to the differential input gears so as to rotate integrally with the differential input gears, the differential case having an opening which connects the inside where the differential gear mechanism is disposed to the outside, the direction along the rotation axis of the differential input gears being an axial direction, the direction perpendicular to the rotation axis being a radial direction, one side in the axial direction being an axial first side, a first side protrusion that is a portion of the differential case that surrounds the first side protrusion and is a first side surrounding portion; the main case includes a specific opposing surface that faces the first side surrounding portion in the radial direction, and a side wall surface that is formed to extend radially inward from an end of the specific opposing surface on the first axial side; the specific opposing surface is arranged radially inward relative to teeth of the differential input gears and is formed to surround the first side surrounding portion from below; an oil level that is highest inside the main case when the differential input gears are stopped is defined as a static oil level, and the opening is located below the static oil level; and an oil retention portion in which oil retains is formed in a space surrounded by the specific opposing surface, the side wall surface, and a surface of the differential input gear that faces the first axial side.

[0008] The oil remaining in the oil stagnation section is less susceptible to being scooped up by the differential input gear. According to this configuration, even when the vehicle starts moving after being stopped for a long period of time, the oil remaining in the oil stagnation section can be introduced into the differential case as the differential case rotates. This facilitates the supply of lubricating oil to the differential case at the beginning of rotation when the differential input gear starts to rotate from a stationary state. Furthermore, because the openings in the differential case are located below the static oil level, oil can be easily introduced into the differential case through the openings at the beginning of rotation. As the differential input gear rotates, the oil circulates within the main case due to the scooping up of the oil, so the oil level within the main case naturally drops. In other words, according to this configuration, the provision of an oil stagnation section allows the lubricating oil to be appropriately supplied to the differential case even at the beginning of rotation without the need to adjust the oil level using a baffle plate, and the stirring resistance of the differential input gear can be reduced after rotation begins. Thus, with this configuration, it is possible to realize a vehicle drive transmission device that can properly supply lubricating oil to the differential case containing the differential gear mechanism, even at the beginning of rotation when the differential input gear that transmits driving force to the differential gear mechanism begins to rotate from a stationary state, without providing a baffle plate.

[0009] Further features and advantages of the vehicle drivetrain will become apparent from the following description of exemplary, non-limiting embodiments thereof, which are given with reference to the drawings. [Brief explanation of the drawings]

[0010] [Figure 1] A skeleton diagram showing an example of a vehicle drive transmission device. [Figure 2] Schematic cross-sectional view of a vehicle drive transmission device taken perpendicular to the axis [Figure 3] Schematic cross-sectional view of a differential gear device as viewed in an axial direction DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of a vehicle drivetrain including a differential gear unit and a main case that houses the differential gear unit and oil will be described with reference to the drawings. As shown in Fig. 1, a vehicle drivetrain 100 according to this embodiment includes a rotating electric machine 2 that is a driving force source for wheels W, an output member (a side gear 43 or a drive shaft 9, described later) that is drivingly connected to the wheels W, a gear mechanism 6 that drivingly connects the rotating electric machine 2 to the output member, and a main case 1 that houses the rotating electric machine 2 and the gear mechanism 6. Although not shown, for example, the main case 1 is partitioned by a partition wall into at least two housing chambers, one of which houses the rotating electric machine 2 and the gear mechanism 6.

[0012] The gear mechanism 6, which is provided in the power transmission path between the rotating electric machine 2 and the output member, is configured with a plurality of gears that drivingly couple the rotating electric machine 2 and the output member. As shown in FIG. 1 , in this embodiment, the plurality of gears include an input gear G23, a counter gear mechanism 3, a differential input gear G34, and a differential gear mechanism 44. The differential gear mechanism 44 distributes the driving force transmitted from the rotating electric machine 2 to the differential input gear G34 via the plurality of gears to each of a pair of wheels W via a pair of side gears 43. These pair of side gears 43 correspond to the output members. In this embodiment, the wheels W and the side gear 43 are coupled via a drive shaft 9. Therefore, this drive shaft 9 can also be considered as the output member. In this case, the pair of side gears 43 of the differential gear mechanism 44 correspond to the output members and can also be considered to be included in the gear mechanism 6.

[0013] The rotating electric machine 2 and the input gear G23 are disposed on a first axis A1, and the counter gear mechanism 3 is disposed on a second axis A2 which is a separate axis parallel to the first axis A1. The differential input gear G34 and the differential gear mechanism 44 are disposed on a third axis A3 which is a separate axis parallel to the first axis A1 and the second axis A2. The drive shaft 9 and wheels W are also disposed on the third axis A3.

[0014] In this application, the term "driving connection" refers to a state in which two rotating elements are connected so as to be able to transmit a driving force, and includes a state in which the two rotating elements are connected so as to rotate integrally, or a state in which the two rotating elements are connected so as to be able to transmit a driving force via one or more transmission members. Such transmission members include various members that transmit rotation at the same speed or at a variable speed, such as a shaft, a gear mechanism, a belt, a chain, etc. The transmission members may also include an engagement device that selectively transmits rotation and driving force, such as a friction engagement device or a meshing engagement device.

[0015] The first axis A1, the second axis A2, and the third axis A3 are different virtual axes and are arranged parallel to one another as described above. In the following description, the direction parallel to the first axis A1 is referred to as the axial direction L. Since the first axis A1 and the second axis A2 are parallel to one another, the axial direction L is also parallel to the second axis A2. Furthermore, since the third axis A3 is also parallel to the first axis A1 and the second axis A2, the axial direction L is also parallel to the third axis A3. Furthermore, one side of the axial direction L (in this embodiment, the side where the rotating electric machine 2 is arranged with respect to the gear mechanism 6) is referred to as the "axial first side L1," and the opposite side is referred to as the "axial second side L2."

[0016] Furthermore, the direction perpendicular to each of the first axis A1, second axis A2, and third axis A3 is referred to as the "radial direction R" based on each axis. When it is not necessary to distinguish which axis is used as the reference or when it is clear which axis is used as the reference, the term "radial direction R" may be used. Furthermore, the direction along the vertical direction when the vehicle drivetrain 100 is mounted on the vehicle is referred to as the "upper-lower direction V," with the upper side referred to as the "upper side V1" and the lower side referred to as the "lower side V2." When the vehicle drivetrain 100 is mounted on the vehicle parallel to the horizontal plane, one direction of the radial direction R coincides with the upper-lower direction V. In the following description, terms relating to the direction, position, etc. of each component are concepts that also include variations due to allowable manufacturing tolerances.

[0017] The rotating electric machine 2 is a rotating electric machine (motor / generator) that operates on multi-phase AC (for example, three-phase AC) and can function as both an electric motor and a generator. The rotating electric machine 2 receives power from a DC power source (not shown) for power running, or generates power using the inertial force of the vehicle and supplies it to the DC power source (regenerates power). The rotating electric machine 2 has a stator 23 fixed to the main case 1 and a rotor 21 rotatably supported inside the stator 23 in the radial direction R. The stator 23 includes a stator core and a stator coil 25 wound around the stator core, and the rotor 21 includes a rotor core and a permanent magnet arranged in the rotor core.

[0018] As shown in FIG. 1 , an input gear G23 is connected to the rotor 21 of the rotating electric machine 2 so as to rotate integrally with the rotor 21. The input gear G23 is connected, for example, to an input shaft which is connected to the rotor shaft of the rotor 21 so as to rotate integrally with the rotor shaft. The input gear G23 may be formed integrally with the input shaft on the outer periphery of the input shaft, or may be formed as a separate member from the input shaft and connected to the input shaft. In either case, the input gear G23 rotates integrally with the rotor 21. The input gear G23 is also drivingly connected to the counter gear mechanism 3.

[0019] The counter gear mechanism 3 is disposed on the second shaft A2, and drivingly couples the rotary electric machine 2 and the differential gear mechanism 44 via an input gear G23 and a differential input gear G34. In this embodiment, the counter gear mechanism 3 has two gears (a first counter gear G31 and a second counter gear G32) that are coupled by a shaft member (a counter shaft) and rotate integrally. That is, the counter gear mechanism 3 is disposed on the second shaft A2, and includes the first counter gear G31 that meshes with the input gear G23, and the second counter gear G32 that rotates integrally with the first counter gear G31 and meshes with the differential input gear G34.

[0020] The differential input gear G34, together with the differential case 40 and the differential gear mechanism 44, constitutes the differential gear device 4. As shown in FIG. 3 , the differential gear device 4 is rotatably supported relative to the main case 1 by a pair of differential bearings B4. The main case 1 includes a main case 11 having an opening on at least one side in the axial direction L, in this case, on the second axial side L2, and a cover case 12 abutting against the main case 11 from the second axial side L2 to close the opening. In this embodiment, the pair of differential bearings B4 are supported by the main case 11 and the cover case 12, respectively. The differential input gear G34 is fixed to a support member 45 using fastening members 46, and the support member 45 is rotatably supported on the main case 1 by the differential bearings B4. The support member 45 constitutes the differential case 40. Note that the differential input gear G34 is not limited to being fixed to the support member 45 using the fastening members 46 so as to rotate integrally therewith, and may be formed integrally with the support member 45 supported by the differential bearings B4.

[0021] The differential gear mechanism 44 is housed in a differential case 40 and includes a pair of pinion gears 41 and a pair of side gears 43 that mesh with the pinion gears 41. The pair of pinion gears 41 and the pair of side gears 43 are both bevel gears, and the differential gear mechanism 44 of this embodiment is a bevel gear type differential gear mechanism. The differential case 40 is a hollow member that houses the pair of pinion gears 41 and the pair of side gears 43. The differential case 40 and the differential input gear G34 are connected to rotate integrally.

[0022] The pair of pinion gears 41 are disposed opposite each other at a distance in the radial direction R based on the third axis A3. A pinion shaft 42 is supported in the differential case 40 so as to rotate integrally with the differential case 40, and the pair of pinion gears 41 are attached to the pinion shaft 42. Each of the pair of pinion gears 41 is rotatable (spins on its own axis) about the pinion shaft 42 and rotatable (revolves) about the third axis A3. A pair of side gears 43 mesh with the pair of pinion gears 41. The pair of side gears 43 are disposed opposite each other across the pinion shaft 42 at a distance in the axial direction L so as to rotate about the third axis A3 as a rotation axis. As shown in FIG. 1 , each side gear 43 is drivingly connected to a pair of drive shafts 9, and each drive shaft 9 is drivingly connected to a pair of wheels W.

[0023] The rotating electric machine 2 and gear mechanism 6 constituting the vehicle drive transmission device 100 are lubricated (and cooled) by oil. Specifically, the oil lubricates and cools the above-mentioned rotor shaft, input shaft, and bearings (not shown) supporting the countershaft, the differential bearing B4, the differential gear mechanism 44 housed in the differential case 40, and the stator coil 25 of the rotating electric machine 2. Hereinafter, these will be collectively referred to as lubrication targets, as appropriate. The lubricating oil can be supplied by a mechanical oil pump (not shown) driven by one or more of the driving power sources of the wheels W (the above-mentioned rotating electric machine 2, and if a separate internal combustion engine is provided, this also includes the internal combustion engine), or an electric oil pump (not shown) driven by a driving power source other than the driving power source of the wheels W (for example, a rotating electric machine (motor) other than the rotating electric machine 2). In addition, after lubricating some of the areas to be lubricated, the oil falls due to gravity and accumulates inside the main case 1 (in an oil reservoir located at the bottom of the main case 1), and can be scooped up by a rotating member housed inside the main case 1 or thrown out by centrifugal force, thereby supplying oil to other areas to be lubricated.

[0024] For example, the gears contained in the differential case 40 that constitute the differential gear mechanism 44 can be lubricated by oil scooped up by the differential input gear G34 and introduced into the differential case 40 through an opening 48 formed in the differential case 40. However, when the differential gear device 4 starts rotating from a stopped state, it takes some time for the oil scooped up by the differential input gear G34 to reach the differential gear mechanism 44 inside the differential case 40. In other words, at the beginning of rotation, there is a possibility that the gears housed in the differential case 40 and supporting members such as bearings may not be sufficiently supplied with oil. For example, when a vehicle starts moving after being stopped for a relatively long time, there is a possibility that the differential gear mechanism 44 may not be sufficiently lubricated immediately after starting. In particular, when the outside temperature is low and the viscosity of the oil is high, it is difficult to introduce oil into the opening 48 of the differential case 40, making it difficult to supply oil to the differential gear mechanism 44 contained in the differential case 40. The vehicle drive transmission device 100 of this embodiment has a structure that can appropriately supply lubricating oil to the differential case 40 that contains the differential gear mechanism 44, even at the beginning of rotation when the differential input gear G34, which transmits driving force to the differential gear mechanism 44, begins to rotate from a stationary state.

[0025] As described above, the differential gear device 4 includes the differential input gear G34 to which driving force from a drive source for the wheels W (here, the rotating electric machine 2) is transmitted, the differential gear mechanism 44 that distributes the driving force transmitted to the differential input gear G34 to a pair of output members (here, side gears 43) that are drivingly connected to a pair of wheels W, and the differential case 40 that is connected to the differential input gear G34 so as to rotate integrally with the differential input gear G34 and that houses the differential gear mechanism 44. The differential case 40 also includes an opening 48 that communicates the interior, where the differential gear mechanism 44 is located, with the outside. The opening 48 is formed in the differential case 40 in addition to openings on both sides in the axial direction L (here, openings for inserting the drive shaft 9). The opening 48 is formed in a middle portion of the differential case 40 in the axial direction L.

[0026] 3, the differential gear mechanism 44 includes a first-side protrusion 5 that is a portion arranged to protrude toward the first axial side L1 relative to the differential input gear G34. That is, in this embodiment, the differential input gear G34 is arranged biased toward the second axial side L2 in the arrangement position of the differential gear mechanism 44 in the axial direction L. The differential case 40 is connected to the differential input gear G34 on the second axial side L2, and the first-side protrusion 5 of the differential gear mechanism 44 is enclosed within the differential case 40 on the first axial side L1 relative to the differential input gear G34. Here, the portion of the differential case 40 that surrounds the first-side protrusion 5 is referred to as a first-side surrounding portion 51.

[0027] Furthermore, in the main case 1, a surface facing the first side surrounding portion 51 in the radial direction R is defined as a specific facing surface 15, and a surface formed to extend from an end of the specific facing surface 15 on the axial first side L1 toward the radially inward direction R1 is defined as a side wall surface 17. In other words, the main case 1 includes the specific facing surface 15 facing the first side surrounding portion 51 in the radial direction R, and the side wall surface 17 formed to extend from an end of the specific facing surface 15 on the axial first side L1 toward the radially inward direction R1. Here, the surface of the differential input gear G34 facing the axial first side L1 is referred to as the axial first side facing surface 49 of the differential input gear G34. As shown in FIG. 3 , when the differential input gear G34 is fastened and fixed to the differential case 40 (here, the support member 45) by inserting a fastening member 46 from the axial first side L1 toward the axial second side L2, the head of the fastening member 46 is also included in the axial first side facing surface 49. 2 and 3, the specific opposing surface 15 is disposed radially inward R1 of the tooth portion 4t of the differential input gear G34. Also, the specific opposing surface 15 is formed in an arc shape as shown in FIG. 2 so as to surround the first side surrounding portion 51 from the lower side V2.

[0028] 2 and 3, the oil level when the differential input gear G34 is stopped and is at its highest inside the main case 1 is defined as the static oil level P0. When the oil level is the static oil level P0, the opening 48 of the differential case 40 is located below the static oil level as shown in FIG. 3. It is sufficient that at least a portion of the opening 48 is located on the side V2 below the static oil level P0. Therefore, when the oil level is the static oil level P0, oil remains in the space E surrounded by the specific opposing surface 15, the side wall surface 17, and the axial first side opposing surface 49, which is the surface facing the axial first side L1 of the differential input gear G34. In other words, an oil retention section 7 where oil remains is formed in the space E surrounded by the specific opposing surface 15, the side wall surface 17, and the axial first side opposing surface 49 of the differential input gear G34.

[0029] The oil remaining in the oil reservoir 7 can enter the inside of the differential case 40 regardless of being scooped up by the differential input gear G34. For example, when the vehicle starts moving after being stopped for an extended period of time, or even when the ambient temperature is low and the oil viscosity is high, the oil remaining in the oil reservoir 7 can be introduced into the differential case 40 as the differential case 40 rotates. For this reason, even at the beginning of rotation when the differential input gear G34 starts to rotate from a stationary state, lubricating oil can be easily supplied to the inside of the differential case 40.

[0030] Furthermore, because the opening 48 provided in the differential case 40 is located on the side V2 below the static oil level P0, oil can easily be introduced into the differential case 40 through the opening 48 at the beginning of rotation. Furthermore, as the differential input gear G34 rotates, the oil scooped up circulates within the main case 1, causing the oil level within the main case 1 to naturally drop. Therefore, the agitation resistance of the differential input gear G34 can be reduced after rotation begins. In other words, even without adjusting the amount of oil by dividing the main case 1 using a separate member, lubricating oil can be appropriately supplied to the differential case 40 even at the beginning of rotation, and the agitation resistance of the differential input gear G34 can be reduced after rotation begins. Separate members for dividing the main case 1 and members for attaching the separate members are not required, and installation work is also not required.

[0031] Note that, as long as the differential input gear G34 is rotating, the oil scooped up by the differential input gear G34 is also introduced into the differential case 40, so oil need not be retained in the oil retention section 7. It is sufficient for oil to be retained in the oil retention section 7 at the beginning of rotation when the differential input gear G34 starts to rotate from a stationary state. Therefore, it is not a problem if oil retains in the oil retention section 7 at a static oil level P0, and as the differential input gear G34 and the differential case 40 begin to rotate, the amount of oil gradually decreases, and the retained oil becomes zero over time. For example, as described below, the amount of oil retained in the oil retention section 7 can be gradually reduced by limiting the amount of oil flowing out of the oil retention section 7. This allows the oil retention section 7 to be configured so that oil temporarily retains oil from the static oil level P0.

[0032] As shown in FIG. 3 , a gap D is provided between the end (axial second-side end 15t) on the second axial side L2 of the specific opposing surface 15 and the first axial-side opposing surface 49 of the differential input gear G34. Therefore, when the differential input gear G34 rotates and the oil level of the oil stored in the main case 1 drops from the static oil level P0 and becomes lower than the specific opposing surface 15, the oil that has been stored in the oil stagnation portion 7 flows out from the gap D to the radially outer side R2. The gap D can be configured to function as a throttle in the flow path of oil that attempts to flow from the oil stagnation portion 7 to the radially outer side R2. By making the gap D between the specific opposing surface 15 and the first axial-side opposing surface 49 of the differential input gear G34 function as a throttle, oil to be introduced into the differential case 40 can be stored in the oil stagnation portion 7 at the beginning of rotation, and the oil in the oil stagnation portion 7 can gradually decrease after rotation has started.

[0033] The gap D (specifically, the size of the gap D in the axial direction L) between the second axial end 15t of the specific opposing surface 15 and the first axial side opposing surface 49 of the differential input gear G34 can be set to a size that is the sum of the maximum error in the position (position in the axial direction L) at which the second axial end 15t is arranged in the main case 1, the maximum error in the assembly position of the differential input gear G34 (assembly position in the axial direction L), and the maximum runout of the differential input gear G34 in the axial direction L. Here, the error in the assembly position of the differential input gear G34 is the error in the position at which the differential input gear G34 is arranged when assembled to the vehicle drive transmission device 100, and includes both errors due to the assembly accuracy of the differential input gear G34 and errors in the shape (dimensions) of the differential input gear G34.

[0034] When the gap D is set in this manner, it is easy to reduce the gap D while avoiding interference between the end portion (axial second-side end portion 15t) on the second axial side L2 of the specific opposing surface 15 and the surface (axial first-side opposing surface 49) facing the first axial side L1 of the differential input gear G34. Furthermore, the gap D can be made to function appropriately as a throttle in the flow path of oil attempting to flow from the oil reservoir 7 to the radially outer side R2. In other words, when the gap D is set in this manner, the throttle can be provided appropriately.

[0035] As described above, the specific opposing surface 15 is disposed radially inward R1 of the tooth portion 4t of the differential input gear G34 and is formed to surround the first side surrounding portion 51 from the lower side V2. The specific opposing surface 15 has a protruding surface 16 that protrudes and bends toward the radially inward R1 on one side in the circumferential direction C, which is the direction around the third axis A3 that is the rotation axis of the differential input gear G34. Specifically, the direction in which the differential case 40 rotates during forward rotation of the wheels W is defined as the circumferential forward side C1, and the protruding surface 16 is provided on the circumferential forward side C1 of the specific opposing surface 15 (see FIG. 2). In other words, the main case 1 has the protruding surface 16 that is formed to protrude toward the radially inward side R1 from the end of the circumferential forward side C1 of the specific opposing surface 15.

[0036] With this configuration, the flow of oil that is dragged by first side enclosing portion 51 of differential case 40 and attempts to rotate together with differential case 40 toward circumferential forward side C1 is restricted by protruding surface 16, making it easy to ensure the amount of oil remaining in oil reservoir portion 7. Therefore, oil that has accumulated in oil reservoir portion 7 can be easily introduced into the interior of differential case 40 through openings 48 provided in differential case 40, making it easy to properly lubricate differential gear mechanism 44 housed within differential case 40.

[0037] 3, the specific opposing surface 15 is disposed so as to overlap with the tooth portion 4t of the differential input gear G34 in a radial view along the radial direction R. Specifically, a portion of the specific opposing surface 15 on the second axial side L2 is disposed so as to overlap with a portion of the tooth portion 4t on the first axial side L1 in a radial view. This facilitates reducing the gap D between the specific opposing surface 15 and the surface of the differential input gear G34 facing the first axial side L1 (the axial first-side opposing surface 49) while ensuring the face width of the differential input gear G34. Therefore, the gap D between the end of the specific opposing surface 15 on the second axial side L2 (the axial second-side end 15t) and the surface of the differential input gear G34 facing the first axial side L1 (the axial first-side opposing surface 49) easily functions as a throttle in the flow path of oil flowing from the oil reservoir 7 to the radially outer side R2. That is, by configuring in this way, the restriction can be appropriately provided while ensuring the tooth width of the differential input gear G34.

[0038] 2, this embodiment is provided with a catch tank 8 that receives and temporarily stores oil inside the main case 1 that is scooped up and scattered by the differential input gear G34. The catch tank 8 is formed, for example, in a space surrounded by a rib 81 that protrudes from the wall surface of the main case 1 in the axial direction L and the wall surface. The oil stored in the catch tank 8 is led to an oil passage (not shown) formed in the main case 1 via a communication hole 83 that opens into the catch tank 8, and via this oil passage, lubricates the rotor shaft, input shaft, counter shaft, input gear G23, first counter gear G31, second counter gear G32, etc.

[0039] The differential input gear G34 scoops up the oil, and as the scooped-up oil circulates within the main case 1, the amount of oil accumulating at the bottom of the main case 1 decreases, so the oil level at the bottom of the main case 1 becomes lower than the static oil level P0. The catch tank 8 extends the time it takes for the oil scooped up by the differential input gear G34 to return to the bottom of the main case 1, allowing the oil level to be lowered further than when the catch tank 8 is not provided. Lowering the oil level reduces the stirring resistance of the differential input gear G34. Here, the dynamic oil level refers to the oil level that fluctuates inside the main case 1 while the differential input gear G34 is rotating. Figures 2 and 3 illustrate the minimum dynamic oil level P1, which is the lowest dynamic oil level. If the minimum dynamic oil level P1 is located above the tooth portion 4t of the differential input gear G34, V1, the differential input gear G34 can scoop up the oil. Therefore, the volume of oil stored in the catch tank 8 is set so that the lowest dynamic oil level P1 does not fall on the side V2 below the tooth portion 4t of the differential input gear G34.

[0040] When the differential input gear G34 rotates, as described above, the amount of oil accumulating at the bottom of the main case 1 decreases, and the oil level also drops. As described above, oil also flows out from the oil accumulating section 7 through the gap D, so the dynamic oil level in the oil accumulating section 7 also drops. In this embodiment, the speed at which the dynamic oil level drops in the oil accumulating section 7 is slower than the speed at which the dynamic oil level drops around the differential input gear G34 while the differential input gear G34 is rotating.

[0041] Because a portion of the oil scooped up by the differential input gear G34 is stored in the catch tank 8, the dynamic oil level, which is the level of oil stored in the lower part of the main case 1 while the differential input gear G34 is rotating, drops compared to the static oil level P0. This drop in the dynamic oil level reduces the agitation resistance of the differential input gear G34. With this configuration, the dynamic oil level around the differential input gear G34 drops more quickly than the dynamic oil level in the oil accumulation section 7. In other words, the oil accumulated in the oil accumulation section 7 decreases more slowly than the oil around the differential input gear G34. As a result, sufficient oil can be secured in the oil accumulation section 7 at the beginning of rotation, allowing oil to be appropriately introduced into the differential case 40.

[0042] The oil retained in the oil retention portion 7 flows out from the oil retention portion 7 to the radially outer side R2 through a gap D between the end portion (axial second side end portion 15t) on the second axial side L2 of the specific opposing surface 15 and the surface (axial first side opposing surface 49) facing the first axial side L1 of the differential input gear G34. Meanwhile, while the differential input gear G34 is rotating, the oil scooped up by the differential input gear G34 falls and flows into the oil retention portion 7. If the amount of oil flowing out of the oil retention portion 7 is greater than the amount of oil flowing into the oil retention portion 7 while the differential input gear G34 is rotating, the oil retained in the oil retention portion 7 gradually approaches zero. Therefore, when the rotation of the differential input gear G34 reaches a steady state, the oil scooped up by the differential input gear G34 can adequately lubricate the differential gear mechanism 44 contained in the differential case 40, and the rotational resistance of the differential case 40 caused by the oil in the oil reservoir 7 can be reduced.

[0043] As described above, according to this embodiment, it is possible to realize a vehicle drive transmission device 100 that can appropriately supply lubricating oil to the differential case 40 that houses the differential gear mechanism 44, even at the initial stage of rotation when the differential input gear G34, which transmits driving force to the differential gear mechanism 44, begins to rotate from a stationary state, without providing a component such as a baffle plate.

[0044] Other Embodiments Other embodiments will be described below. Note that the configurations of the embodiments described below are not limited to being applied independently, and can also be applied in combination with the configurations of other embodiments as long as no contradiction occurs.

[0045] (1) In the above description, the vehicle drive transmission device 100 has been described as having a three-shaft configuration in which the first shaft A1, the second shaft A2, and the third shaft A3 are arranged in parallel. However, the vehicle drive transmission device 100 may have a two-shaft configuration in which the first shaft A1 and the second shaft A2 are arranged in parallel. The vehicle drive transmission device 100 may also have a configuration in which one or more axes other than the first shaft A1, the second shaft A2, and the third shaft A3 are arranged in parallel, resulting in four or more axes being arranged in parallel. The vehicle drive transmission device 100 may also have a single-shaft configuration in which the rotating electric machine 2, the gear mechanism 6, and the differential gear mechanism 44 are arranged on the same axis.

[0046] (2) In the above description, the vehicle drivetrain 100 is illustrated as having a rotating electric machine 2 as a drive power source for the wheels W, but the drive power source may be an internal combustion engine. The vehicle drivetrain 100 may also be a hybrid drivetrain (for example, various types of hybrid drivetrains such as a so-called one-motor parallel type or two-motor split type) that has both an internal combustion engine and a rotating electric machine 2 as a drive power source for the wheels W of the vehicle.

[0047] (3) In the above, with reference to Fig. 3, an example has been given of a configuration in which the differential input gear G34 is disposed closest to the second axial side L2 of the differential gear device 4, and all of the gear units constituting the differential gear mechanism 44 are disposed so as to protrude toward the first axial side L1 relative to the differential input gear G34, corresponding to the first-side protruding portion 5. However, the differential gear device 4 may also be configured such that some of the gear units constituting the differential gear mechanism 44 are also disposed on the second axial side L2 relative to the differential input gear G34.

[0048] (4) In the above example, the main case 1 includes the protruding surface 16 formed to protrude radially inward R1 from the end of the circumferential forward rotation side C1 of the specific opposing surface 15. However, the main case 1 may also include a second protruding surface formed to protrude radially inward R1 from the end of the specific opposing surface 15 on the side on which the differential case 40 rotates during reverse rotation of the wheels W, i.e., on the reverse circumferential side opposite the circumferential forward rotation side C1. In this case, oil can be appropriately introduced into the differential case 40 even at the beginning of rotation of the differential input gear G34 when a stopped vehicle starts moving in the direction in which the wheels W reverse.

[0049] (5) In the above, examples have been given of main case 1 having protruding surface 16 and having protruding surface 16 and second protruding surface, but it is not necessary for main case 1 to have protruding surface 16 or second protruding surface. If protruding surface 16 or second protruding surface is provided, it will regulate the flow of oil that tends to rotate together with differential case 40 due to being dragged by first side enclosing portion 51 of differential case 40, making it easier to ensure the amount of oil remaining in oil reservoir 7. However, because opening 48 of differential case 40 is located on side V2 below static oil level P0, oil will still be introduced through opening 48 when differential case 40 begins to rotate. Therefore, this does not preclude a configuration that does not have protruding surface 16 or second protruding surface.

[0050] (6) In the above example, the gap D between the second axial end 15t of the specific opposing surface 15 and the first axial opposing surface 49 of the differential input gear G34 is configured to function as a throttle. However, this gap D does not necessarily have to function as a throttle. At least during the first rotation, a small amount of oil remaining in the oil reservoir 7 is introduced into the differential case 40. Then, oil is also introduced into the differential case 40 from the opening 48 at least until the static oil level P0 becomes lower than the opening 48 of the differential case 40. Therefore, this does not prevent a configuration in which oil flows out of the oil reservoir 7 faster than the reduction rate that would occur if a throttle were provided.

[0051] (7) In the above, an example has been given in which the gap D between the second axial end 15t of the specific opposing surface 15 and the first axial end 49 of the differential input gear G34 is set to a size that is the sum of the maximum error in the position where the second axial end 15t is arranged in the main case 1, the maximum error in the assembly position of the differential input gear G34, and the maximum swing width of the differential input gear G34 in the axial direction L. Setting the gap D in this way allows the throttle to be appropriately provided, but does not prevent an increase in the amount of oil outflow from the oil reservoir 7, and the gap D may be larger than this.

[0052] (8) In the above, an example has been given in which the specific opposing surface 15 is provided so as to overlap the tooth portion 4t of the differential input gear G34 as viewed in the radial direction. This makes it easy to reduce the gap D between the specific opposing surface 15 and the surface of the differential input gear G34 facing the axial first side L1 (the axial first-side opposing surface 49) while ensuring the face width of the differential input gear G34, and makes it easy to appropriately set the function as a throttle. However, this does not prevent an increase in the amount of oil flowing out from the oil reservoir 7, and does not prevent a configuration in which the specific opposing surface 15 does not overlap the tooth portion 4t of the differential input gear G34 as viewed in the radial direction.

[0053] (9) In the above, an example was given of a configuration in which a catch tank 8 is provided to temporarily store a portion of the oil scooped up by the differential input gear G34, but this does not preclude a configuration in which a catch tank 8 is not provided. The oil scooped up by the differential input gear G34 flows downward after splashing into the main case 1, so the oil level drops compared to the static oil level P0 while the differential input gear G34 is rotating. Therefore, the stirring resistance of the differential input gear G34 decreases by the amount of the drop in the oil level. A configuration in which a catch tank 8 is not provided is also acceptable as long as a structure is provided that can appropriately supply oil to the parts to be lubricated.

[0054] (10) The above example illustrates a configuration in which the amount of oil flowing out of the oil retention section 7 during rotation of the differential input gear G34 is greater than the amount of oil flowing into the oil retention section 7. However, this does not preclude a configuration in which the amount of oil flowing out of the oil retention section 7 is equal to the amount of oil flowing into the oil retention section 7, or a configuration in which the amount of oil flowing into the oil retention section 7 is greater than the amount of oil flowing out of the oil retention section 7.

[0055] [Summary of this embodiment] The above-described vehicle drive transmission device (100) will be briefly summarized below.

[0056] In one embodiment, the vehicle drive transmission device (100) is provided with a differential gear device (4) and a main case (1) that accommodates the differential gear device (4) and oil therein, and the differential gear device (4) includes a differential input gear (G34) to which a driving force from a driving source (2) of wheels (W) is transmitted, a differential gear mechanism (44) that distributes the driving force transmitted to the differential input gear (G34) to a pair of output members (9, 43) that are drivingly connected to a pair of the wheels (W), and a differential gear mechanism (44) that rotates integrally with the differential input gear (G34). and a differential case (40) that houses the differential gear mechanism (44) and is connected to the differential input gear (G34) so ​​as to rotate, the differential case (40) having an opening (48) that communicates the inside where the differential gear mechanism (44) is arranged with the outside, a direction along the rotation axis (A3) of the differential input gear (G34) is defined as an axial direction (L), a direction perpendicular to the rotation axis (A3) is defined as a radial direction (R), one side of the axial direction (L) is defined as a first axial side (L1), and the differential gear mechanism (44) protrudes from the first axial side (L1) relative to the differential input gear (G34). a first side surrounding portion (51) surrounding the first side protrusion portion (5) in the differential case (40); and a first side surrounding portion (51) surrounding the first side protrusion portion (5) in the differential case (40). The main case (1) includes a specific opposing surface (15) facing the first side surrounding portion (51) in the radial direction (R), and a side wall surface (17) formed to extend from an end of the specific opposing surface (15) on the axial first side (L1) to an inner side (R1) in the radial direction (R). The specific opposing surface (15) is located closer to the radial direction (R) than the tooth portion (4t) of the differential input gear (G34). The opening (48) is positioned on the inside (R1) of the direction (R) and is formed to surround the first side enclosing portion (51) from the lower side (V2). The static oil level (P0) is the oil level when the differential input gear (G34) is stopped and is at its highest inside the main case (1), and the opening (48) is positioned on the lower side (V2) of the static oil level (P0). An oil retention portion (7) in which oil retains is formed in a space surrounded by the specific opposing surface (15), the side wall surface (17), and a surface (49) of the differential input gear (G34) facing the first axial side (L1).

[0057] The oil remaining in the oil reservoir (7) is less susceptible to being scooped up by the differential input gear (G34). According to this configuration, even when the vehicle starts moving after being stopped for a long period of time, the oil remaining in the oil reservoir (7) can be introduced into the differential case (40) as the differential case (40) rotates. This facilitates supply of lubricating oil to the differential case (40) at the initial stage of rotation when the differential input gear (G34) starts to rotate from a stationary state. Furthermore, because the opening (48) provided in the differential case (40) is located below (V2) the static oil level (P0), oil can also be easily introduced into the differential case (40) through the opening (48) at the initial stage of rotation. When the differential input gear (G34) rotates, the oil is scooped up and circulates within the main case (1), so the oil level within the main case (1) naturally drops. That is, according to this configuration, by providing the oil reservoir (7), lubricating oil can be appropriately supplied to the differential case (40) even at the beginning of rotation without adjusting the oil level using a baffle plate, and the stirring resistance of the differential input gear (G34) can be reduced after rotation has started. Thus, according to this configuration, it is possible to realize a vehicle drive transmission device (100) that can appropriately supply lubricating oil to the differential case (40) containing the differential gear mechanism (44) even at the beginning of rotation when the differential input gear (G34), which transmits driving force to the differential gear mechanism (44), starts to rotate from a stationary state, without providing a baffle plate.

[0058] Here, it is preferable that the other side in the axial direction (L) is defined as the second axial side (L2), and the gap (D) between the end (15t) of the specific opposing surface (15) on the second axial side (L2) and the surface (49) facing the first axial side (L1) of the differential input gear (G34) is configured to function as a throttle in the flow path of oil attempting to flow from the oil stagnation portion (7) to the outside (R2) in the radial direction (7).

[0059] A gap (D) is provided between the end (15t) on the second axial side (L2) of the specific opposing surface (15) and the surface (49) of the differential input gear (G34) facing the first axial side (L1), so that when the differential input gear (G34) rotates and the oil level of the oil stored in the main case (1) drops from the static oil level (P0) and becomes lower than the specific opposing surface (15), the oil that has been stored in the oil accumulation portion (7) flows out from the gap (D) to the radially outer side (R2). According to this configuration, the gap (D) is set to function as a throttle in the flow path of oil that attempts to flow from the oil accumulation portion (7) to the radially outer side (R2). By making the gap (D) between the specific opposing surface (15) and the surface (49) facing the first axial side (L1) of the differential input gear (G34) function as a throttle, the oil to be introduced into the differential case (40) is retained in the oil retention section (7) at the beginning of rotation, and after the start of rotation, the oil in the oil retention section (7) gradually decreases.

[0060] Furthermore, the direction going around the rotation axis (A3) is defined as a circumferential direction (C), and the side on which the differential case (40) rotates during forward rotation of the wheels (W) is defined as a circumferential forward side (C1), and it is preferable that the main case (1) further comprises a protruding surface (16) formed to protrude from the end of the specific opposing surface (15) on the circumferential forward side (C1) toward the inside (R1) in the radial direction (R).

[0061] With this configuration, the protruding surface (16) restricts the flow of oil that tends to rotate together with the differential case (40) in the forward circumferential direction (C1) due to being dragged by the first side surrounding portion (51) of the differential case (40), thereby making it easy to ensure an amount of oil remaining in the oil accumulation portion (7). Therefore, the oil accumulated in the oil accumulation portion (7) can be easily introduced into the differential case (40) through the opening (48) provided in the differential case (40), making it easy to properly lubricate the differential gear mechanism (44) housed in the differential case (40).

[0062] Preferably, the specific opposing surface (15) is provided so as to overlap with a tooth portion (4t) of the differential input gear (G34) when viewed in the radial direction (R).

[0063] This configuration makes it easy to reduce the gap (D) between the specific opposing surface (15) and the surface (49) of the differential input gear (G34) facing the first axial side (L1) while ensuring the face width of the differential input gear (G34). Therefore, the gap (D) between the end (15t) of the specific opposing surface (15) on the second axial side (L2) and the surface (49) of the differential input gear (G34) facing the first axial side (L1) can easily function as a throttle in the flow path of oil attempting to flow from the oil reservoir portion (7) to the radially outer side (R2). In other words, this configuration makes it possible to appropriately provide the throttle while ensuring the face width of the differential input gear (G34).

[0064] Furthermore, with the other side in the axial direction (L) being the second axial side (L2), it is preferable that the gap (D) between the end (15t) of the specific opposing surface (15) on the second axial side (L2) and the surface (49) of the differential input gear (G34) facing the first axial side (L1) be set to a size that is the sum of the maximum error in the position where the end (15t) of the specific opposing surface (15) on the second axial side (L2) is positioned in the main case (1), the maximum error in the assembly position of the differential input gear (G34), and the maximum swing width of the differential input gear (G34) in the axial direction (L).

[0065] When the gap (D) is set in this manner, it is easy to reduce the gap (D) while avoiding interference between the end (15t) on the second axial side (L2) of the specific opposing surface (15) and the surface (49) facing the first axial side (L1) of the differential input gear (G34). Furthermore, the gap (D) can be made to function appropriately as a throttle in the flow path of oil attempting to flow from the oil reservoir portion (7) to the radially outer side (R2). In other words, when the gap (D) is set in this manner, the throttle can be provided appropriately.

[0066] Furthermore, the vehicle drive transmission device (100) is preferably provided with a catch tank (8) that temporarily stores oil in the main case (1), and the oil level that fluctuates inside the main case (1) during rotation of the differential input gear (G34) is defined as a dynamic oil level, and the rate at which the dynamic oil level decreases in the oil stagnation section (7) is slower than the rate at which the dynamic oil level decreases around the differential input gear (G34).

[0067] Because a portion of the oil scooped up by the differential input gear (G34) is stored in the catch tank (8), the dynamic oil level, which is the level of oil stored in the lower part of the main case (1) while the differential input gear (G34) is rotating, drops below the static oil level (P0). This drop in the dynamic oil level reduces the agitation resistance of the differential input gear (G34). According to this configuration, the dynamic oil level around the differential input gear (G34) drops faster than the dynamic oil level in the oil accumulation section (7). In other words, the oil accumulated in the oil accumulation section (7) decreases more slowly than the oil around the differential input gear (G34). Therefore, at the beginning of rotation, a sufficient amount of oil can be secured in the oil accumulation section (7), allowing the oil to be appropriately introduced into the differential case (40).

[0068] In addition, it is preferable that the vehicle drive transmission device (100) is configured such that the amount of oil flowing out of the oil stagnation section (7) is greater than the amount of oil flowing into the oil stagnation section (7) during rotation of the differential input gear (G34).

[0069] The oil remaining in the oil retention portion (7) flows out from the oil retention portion (7) to the radially outer side (R2) through the gap (D) between the end portion (15t) on the second axial side (L2) of the specific opposing surface (15) and the surface (49) facing the first axial side (L1) of the differential input gear (G34). Meanwhile, while the differential input gear (G34) is rotating, the oil scooped up by the differential input gear (G34) also falls and flows into the oil retention portion (7). If the amount of oil flowing out of the oil retention portion (7) is greater than the amount of oil flowing into the oil retention portion (7) while the differential input gear (G34) is rotating, the oil remaining in the oil retention portion (7) gradually approaches zero. Therefore, when the rotation of the differential input gear (G34) reaches a steady state, the oil scooped up by the differential input gear (G34) can adequately lubricate the differential gear mechanism (44) contained in the differential case (40), and the rotational resistance of the differential case (40) caused by the oil in the oil reservoir (7) can be reduced. [Explanation of symbols]

[0070] 1: Main case, 2: Rotating electric machine (wheel driving source), 4: Differential gear device, 4t: Tooth portion, 5: First side protrusion, 7: Oil retention portion, 8: Catch tank, 9: Drive shaft (output member), 15: Specific opposing surface, 15t: Axial second side end portion (the axial second side end portion of the specific opposing surface), 16: Protruding surface, 17: Side wall surface, 40: Differential case, 43: Side gear (output member), 44: Differential gear mechanism, 48: Opening (opening formed in the differential case to allow oil to flow), 49: Axial first side opposing surface (surface facing the axial first side of the differential input gear), 51: First side Enclosure, 100: vehicle drive transmission device, A3: third shaft (rotation axis of differential input gear), C: circumferential direction, C1: circumferential forward side, D: gap (gap between the end of the specific opposing surface on the second axial side and the surface of the differential input gear facing the first axial side), E: space (space surrounded by the specific opposing surface, side wall surface, and the surface of the differential input gear facing the first axial side), G34: differential input gear, L: axial direction, L1: axial first side, L2: axial second side, P0: static oil level, R: radial direction, R1: radial inner side (radial inner side), R2: radial outer side (radial outer side), V2: lower side, W: wheel

Claims

1. A drive transmission device for a vehicle including a differential gear device and a main case that accommodates the differential gear device and oil therein, The differential gear device is a differential input gear to which driving force from a drive source of the wheels is transmitted; a differential gear mechanism that distributes the driving force transmitted to the differential input gear to a pair of output members that are drivingly connected to a pair of the wheels, respectively; a differential case that is connected to the differential input gear so as to rotate integrally with the differential gear mechanism and that houses the differential gear mechanism, the differential case has an opening communicating an interior in which the differential gear mechanism is disposed with an exterior, A direction along the rotation axis of the differential input gear is defined as an axial direction, a direction perpendicular to the rotation axis is defined as a radial direction, and one side in the axial direction is defined as an axial first side, the differential gear mechanism includes a first side protrusion that is a portion arranged to protrude toward a first side in the axial direction relative to the differential input gear, a portion of the differential case surrounding the first side protrusion portion as a first side surrounding portion, the main case includes a specific opposing surface that faces the first side surrounding portion in the radial direction, and a side wall surface that is formed so as to extend radially inward from an end portion of the specific opposing surface on the first axial side, the specific opposing surface is disposed radially inward of the teeth of the differential input gear and is formed to surround the first side surrounding portion from below, The static oil level is the oil level at the highest point inside the main case when the differential input gear stops, and The opening is located below the static oil level, an oil retention portion in which oil retains is formed in a space surrounded by the specific opposing surface, the side wall surface, and a surface of the differential input gear facing the first axial side, The specific opposing surface is provided so as to overlap with teeth of the differential input gear when viewed in the radial direction.

2. The other side in the axial direction is defined as a second axial side, 2. The vehicle drive transmission device according to claim 1, wherein a gap between the end of the specific opposing surface on the second axial side and a surface of the differential input gear facing the first axial side is configured to function as a throttle in a flow path of oil attempting to flow radially outward from the oil stagnation portion.

3. The direction around the rotation axis is defined as a circumferential direction, and the side on which the differential case rotates during forward rotation of the wheels is defined as a forward circumferential side, 3. The vehicle drive transmission device according to claim 1, wherein the main case further comprises a protruding surface formed so as to protrude radially inward from an end of the specific opposing surface on the forward circumferential side.

4. The other side in the axial direction is defined as a second axial side, 3. The vehicle drive transmission device according to claim 1, wherein the gap between the end of the specific opposing surface on the second axial side and the surface of the differential input gear facing the first axial side is set to a size that is the sum of the maximum error in the position where the end of the specific opposing surface on the second axial side is positioned on the main case, the maximum error in the assembly position of the differential input gear, and the maximum axial runout of the differential input gear.

5. A catch tank is provided to temporarily store oil in the main case, The oil level that fluctuates inside the main case during rotation of the differential input gear is defined as a dynamic oil level, 3. The vehicle drive transmission device according to claim 1, wherein the rate at which the dynamic oil level drops in the oil reservoir is slower than the rate at which the dynamic oil level drops around the differential input gear.

6. 3. The vehicle drive transmission device according to claim 1, wherein an amount of oil flowing out of the oil reservoir during rotation of the differential input gear is greater than an amount of oil flowing into the oil reservoir.

7. A drive transmission device for a vehicle comprising a differential gear device and a main case that accommodates the differential gear device and oil therein, The differential gear device is a differential input gear to which driving force from a drive source of the wheels is transmitted; a differential gear mechanism that distributes the driving force transmitted to the differential input gear to a pair of output members that are drivingly connected to a pair of the wheels, respectively; a differential case that is connected to the differential input gear so as to rotate integrally with the differential gear mechanism and that houses the differential gear mechanism, the differential case has an opening communicating an interior in which the differential gear mechanism is disposed with an exterior, A direction along the rotation axis of the differential input gear is defined as an axial direction, a direction perpendicular to the rotation axis is defined as a radial direction, and one side in the axial direction is defined as an axial first side, the differential gear mechanism includes a first side protrusion that is a portion arranged to protrude toward a first side in the axial direction relative to the differential input gear, a portion of the differential case surrounding the first side protrusion portion as a first side surrounding portion, the main case includes a specific opposing surface that faces the first side surrounding portion in the radial direction, and a side wall surface that is formed so as to extend radially inward from an end portion of the specific opposing surface on the first axial side, the specific opposing surface is disposed radially inward of the teeth of the differential input gear and is formed to surround the first side surrounding portion from below, The static oil level is the oil level at the highest point inside the main case when the differential input gear stops, and The opening is located below the static oil level, an oil retention portion in which oil retains is formed in a space surrounded by the specific opposing surface, the side wall surface, and a surface of the differential input gear facing the first axial side, A catch tank is provided to temporarily store oil in the main case, The oil level that fluctuates inside the main case during rotation of the differential input gear is defined as a dynamic oil level, A vehicle drive transmission device, wherein the rate at which the dynamic oil level drops in the oil stagnation portion is slower than the rate at which the dynamic oil level drops around the differential input gear.

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