Patent Description:
Patent Documents <NUM> discloses a power transmission device with a bevel gear differential mechanism. The differential mechanism includes a pinion mate gear and a pinion mate shaft housed in a differential case.

Patent Document <NUM> : <CIT> <CIT> discloses a power transmission device.

It is desirable to improve the freedom of assembly for the power transmission device.

A power transmission device according to the present invention includes;.

Particular embodiments of the invention are laid down in the dependent claims.

According to the present invention, the freedom of assembly can be improved.

First, definitions of terms used in this specification will be described. A power transmission device is a device that has at least a power transmission mechanism. The power transmission device can be, for example, a gear mechanism and/or a differential gear mechanism.

When a second element (component, part, etc.) connected to a first element (component, part, etc.), a second element (component, part, etc.) connected downstream of the first element (component, part, etc.), or a second element (component, part, etc.) connected upstream of the first element (component, part, etc.) is mentioned, it means that the first and second elements are connected for power transmission. The input side of power is upstream, and the output side of power is downstream. The first and second elements may be connected via other elements (clutch, other gear mechanism, etc.).

"Overlap in a predetermined direction of view" means that multiple elements are arranged in a predetermined direction, and "overlap in a predetermined direction" is equivalent to this description. "Predetermined direction" can be, for example, axial direction, radial direction, gravity direction, vehicle travel direction (forward direction or backward direction of the vehicle), and the like.

If multiple elements (components, parts, etc.) are shown arranged in a predetermined direction on the drawings, it may be assumed that there is a description in the specification explaining that they overlap in a predetermined direction of view.

"Not overlapping in a predetermined direction of view" or "offset in a predetermined direction of view" means that multiple elements are not arranged in a predetermined direction, and "not overlapping in a predetermined direction" or "offset in a predetermined direction" is equivalent to this description. "Predetermined direction" can be, for example, axial direction, radial direction, gravity direction, vehicle travel direction (forward direction or backward direction of the vehicle), and the like.

If multiple elements (components, parts, etc.) are shown not arranged in a predetermined direction on the drawings, it may be assumed that there is a description in the specification explaining that they do not overlap in a predetermined direction of view.

The phrase "in a predetermined direction of view, the first element (component, part, etc.) is positioned between the second element (component, part, etc.) and the third element (component, part, etc.)" means that when observed from the predetermined direction, the first element can be observed to be located between the second and third elements. The "predetermined direction" refers to the axial direction, radial direction, gravity direction, vehicle travel direction (forward or backward), etc..

For example, if the second element, first element, and third element are arranged in that order along the axial direction, the first element can be said to be positioned between the second and third elements when viewed radially. If it is shown in the drawings that the first element is located between the second and third elements in a predetermined direction of view, it can be assumed that the description in the specification explains that the first element is positioned between the second and third elements in the predetermined direction of view.

When two elements (parts, components, etc.) overlap in the axial direction, the two elements are coaxial.

"Axial direction" refers to the axial direction of the rotating axis of the components that make up the power transmission device. "Radial direction" refers to the direction perpendicular to the rotating axis of the components that make up the power transmission device. Examples of components include motors, gear mechanisms, differential gear mechanisms, etc..

The rotation elements (such as sun gear, carrier, ring gear) of the planetary gear mechanism are "fixed" to other elements, which means that they can be directly fixed or fixed via another member.

The following describes embodiments of the present invention.

<FIG> is a skeleton parts diagram illustrating a power transmission device <NUM>.

<FIG> is a schematic sectional view illustrating the power transmission device <NUM>.

<FIG> is an enlarged view around the planetary reduction gear <NUM> of the power transmission device <NUM>.

<FIG> is an enlarged view around the differential mechanism <NUM> of the power transmission device <NUM>.

As shown in <FIG>, the power transmission device <NUM> has a motor <NUM>, a planetary reduction gear <NUM> (reduction mechanism), and a differential mechanism <NUM>. The power transmission device <NUM> also has drive shafts 9A and 9B and a park lock mechanism <NUM>.

Along the transmission path of the output rotation of the motor <NUM> around its rotation axis X, the park lock mechanism <NUM>, the planetary reduction gear <NUM>, the differential mechanism <NUM>, and the drive shafts 9A and 9B are provided. The planetary reduction gear <NUM> is connected downstream of the motor <NUM>. The differential mechanism <NUM> is connected downstream of the planetary reduction gear <NUM>. The drive shafts 9A and 9B are connected downstream of the differential mechanism <NUM>. The drive shafts 9A and 9B are respectively connected to one side and the other side of the rotation axis X of the differential mechanism <NUM>. The axis lines of the drive shafts 9A and 9B are coaxial with the rotation axis X of the motor <NUM>. Each of the drive shafts 9A and 9B are connected to left and right drive wheels W of the vehicle.

Motor <NUM> is a rotary electric machine having at least one of an electric motor function and a power generation function. In the power transmission device <NUM>, the output rotation of the motor <NUM> is reduced by the planetary reduction gear <NUM> and input to the differential mechanism <NUM>. The differential mechanism <NUM> transmits rotation to the drive wheels W through the drive shafts 9A and 9B.

As shown in <FIG>, the main box <NUM> of the power transmission device <NUM> has a first box <NUM> that houses the motor <NUM> and a second box <NUM> that is extrapolated from the first box <NUM>. The main box <NUM> also has a third box <NUM> that is assembled to the first box <NUM> and a fourth box <NUM> that is assembled to the second box <NUM>.

The first box <NUM> has a cylindrical support wall portion <NUM> and a flange-like joint portion <NUM> provided at one end 111a of the support wall portion <NUM>.

The first box <NUM> is provided in a direction in which the support wall portion <NUM> is aligned with the rotation axis X of the motor <NUM>. The motor <NUM> is accommodated inside the support wall portion <NUM>.

The joint portion <NUM> is provided in a direction perpendicular to the rotation axis X. The joint portion <NUM> is formed with a larger outer diameter than the support wall portion <NUM>.

The second box <NUM> has a cylindrical circumferential wall portion <NUM>, a flange-like joint portion <NUM> provided at one end 121a of the circumferential wall portion <NUM>, and a flange-like joint portion <NUM> provided at the other end 121b of the circumferential wall portion <NUM>.

The circumferential wall portion <NUM> is formed with an inner diameter that can be fitted over the support wall portion <NUM> of the first box <NUM>.

The first box <NUM> and the second box <NUM> are assembled by fitting the circumferential wall portion <NUM> of the second box <NUM> over the support wall portion <NUM> of the first box <NUM>.

The joint portion <NUM> on the end 121a side of the circumferential wall portion <NUM> is in contact with the joint portion <NUM> of the first box <NUM> in the direction of the rotation axis X. These joint portions <NUM> and <NUM> are connected to each other by bolts (not shown).

In the first box <NUM>, a plurality of grooves 111b are provided on the outer periphery of the support wall portion <NUM>. The plurality of grooves 111b are provided at intervals in the direction of the rotation axis X. Each of the grooves 111b is provided over the entire circumference in the circumferential direction around the rotation axis X.

The circumferential wall portion <NUM> of the second box <NUM> is inserted into the support wall portion <NUM> of the first box <NUM>. The openings of the grooves 111b are closed by the circumferential wall portion <NUM>. A plurality of cooling passages CP through which cooling water flows are formed between the support wall portion <NUM> and the circumferential wall portion <NUM>.

On the outer circumference of the support wall portion <NUM> of the first box <NUM>, ring grooves 111c and 111c are formed on both sides of the area where the grooves 111b are provided. The seal rings <NUM> and <NUM> are fitted and attached to the ring grooves 111c and 111c, respectively.

These seal rings <NUM> press-fit into the inner circumference of the circumferential wall portion <NUM> extrapolated to the support wall portion <NUM>, and seal the gap between the outer circumference of the support wall portion <NUM> and the inner circumference of the circumferential wall portion <NUM>.

The other end 121b of the second box <NUM> has a wall portion <NUM> extending on the inner diameter side. The wall portion <NUM> is provided in a direction perpendicular to the rotation axis X. An opening 120a through which the drive shaft 9A is inserted is provided in an area where the wall portion <NUM> intersects the rotation axis X.

On the side (right side in the figure) of the motor <NUM> in the wall portion <NUM>, a cylindrical motor supporting portion <NUM> surrounding the opening 120a is provided.

The motor supporting portion <NUM> is inserted inside the coil end 253b to be described later. The motor supporting portion <NUM> faces the end portion 21b of the rotor core <NUM> with a gap in the X-axis direction.

The circumferential wall portion <NUM> of the second box <NUM> has a thicker radial thickness in a lower region in the vertical direction based on the mounting state of the power transmission device <NUM> on a vehicle than in an upper region.

In this region with a thicker radial thickness, an oil pooling portion <NUM> penetrating in the axial direction of the rotation axis X is provided.

The oil pooling portion <NUM> communicates with an axial oil passage <NUM> provided in the joint portion <NUM> of the third box <NUM> through a communication hole 112a. The communication hole 112a is provided in the joint portion <NUM> of the first box <NUM>.

The third box <NUM> has a wall portion <NUM> orthogonal to the rotation axis X. A joint portion <NUM> forming a ring shape when viewed from the direction of the rotation axis X is provided on the outer peripheral portion of the wall portion <NUM>.

The third box <NUM> is located on the opposite side (right side in the figure) from the differential mechanism <NUM> when viewed from the first box <NUM>. The joint portion <NUM> of the third box <NUM> is joined to the joint portion <NUM> of the first box <NUM> from the direction of the rotation axis X. The third box <NUM> and the first box <NUM> are connected to each other by bolts (not shown). In this state, the opening of the first box <NUM> on the joint portion <NUM> side (right side in the figure) of the support wall portion <NUM> is blocked by the third box <NUM>.

In the third box <NUM>, a through-hole 130a of the drive shaft 9A is provided at the center of the wall portion <NUM>.

A lip seal RS is provided on the inner circumference of the through-hole 130a. The lip seal RS elastically contacts an unillustrated lip portion with the outer circumference of the drive shaft 9A. The gap between the inner circumference of the through-hole 130a and the outer circumference of the drive shaft 9A is sealed by the lip seal RS.

On the side of the first box <NUM> (left side in the figure) of the wall portion <NUM>, a circumferential wall portion <NUM> surrounding the through-hole 130a is provided. The drive shaft 9A is supported by bearing B4 through the inner circumference of the circumferential wall portion <NUM>.

A motor supporting portion <NUM> is provided on the motor <NUM> side (left side in the figure) from the circumferential wall portion <NUM>. The motor supporting portion <NUM> forms a cylindrical shape surrounding the rotation axis X at a distance.

On the outer periphery of the motor supporting portion <NUM>, a cylindrical connecting wall <NUM> is connected. The connecting wall <NUM> is formed with a larger outer diameter than the circumferential wall portion <NUM> on the wall portion <NUM> side (right side in the figure). The connecting wall <NUM> is provided in the direction along the rotation axis X and extends away from the motor <NUM>. The connecting wall <NUM> connects the motor supporting portion <NUM> and the wall portion <NUM> of the third box <NUM>.

The motor supporting portion <NUM> is supported by the third box <NUM> via a connecting wall <NUM>. The inside of the motor supporting portion <NUM> is penetrated by one end 20a of the motor shaft <NUM> from the motor <NUM> side to the circumferential wall portion <NUM> side.

A bearing B1 is supported on the inner circumference of the motor supporting portion <NUM>. The outer circumference of the motor shaft <NUM> is supported by the motor supporting portion <NUM> via the bearing B1.

A lip seal RS is provided in a position adjacent to the bearing B1.

Oil holes 136a to be described later are opened on the inner circumference of the connecting wall <NUM> in the third box <NUM>. The oil OL flows into the internal space Sc surrounded by the connecting wall <NUM> through the oil hole 136a. The lip seal RS is provided to prevent the oil OL inside the connecting wall <NUM> from flowing into the motor <NUM> side.

The fourth box <NUM> has a circumferential wall portion <NUM> that surrounds the outer periphery of the planetary reduction gear <NUM> and the differential mechanism <NUM>, and a flange-like joint portion <NUM> provided at the end on the side of the second box <NUM> in the circumferential wall portion <NUM>. The fourth box <NUM> functions as a box that accommodates the planetary reduction gear <NUM> and the differential mechanism <NUM>.

The fourth box <NUM> is located on the differential mechanism <NUM> side (left side in the drawing) when viewed from the second box <NUM>. The joint portion <NUM> of the fourth box <NUM> is joined to the joint portion <NUM> of the second box <NUM> from the direction of the rotation axis X. The fourth box <NUM> and the second box <NUM> are connected to each other by bolts (not shown).

The inside of the main box <NUM> of the power transmission device <NUM> has a motor chamber Sa for accommodating the motor <NUM>, and a gear compartment Sb for accommodating the planetary reduction gear <NUM> and the differential mechanism <NUM>.

The motor chamber Sa is formed inside the first box <NUM>, between the wall portion <NUM> of the second box <NUM> and the wall portion <NUM> of the third box <NUM>.

The gear chamber Sb is formed on the inner diameter side of the fourth box <NUM>, between the wall portion <NUM> of the second box <NUM> and the circumferential wall portion <NUM> of the fourth box <NUM>.

A plate member <NUM> is provided inside the gear compartment Sb. The plate member <NUM> is fixed to the fourth box <NUM>.

The plate member <NUM> divides the gear compartment Sb into a first gear compartment Sb1 for accommodating the planetary reduction gear <NUM> and the differential mechanism <NUM>, and a second gear chamber Sb2 for accommodating the park lock mechanism <NUM>.

In the direction of the rotation axis X, the second gear compartment Sb2 is located between the first gear compartment Sb1 and the motor compartment Sa.

The motor <NUM> has a motor shaft <NUM>, a rotor core <NUM>, and a stator core <NUM>. The motor shaft <NUM> and rotor core <NUM> are cylindrical. The rotor core <NUM> is extrapolated onto the motor shaft <NUM>. The stator core <NUM> surrounds the outer circumference of the rotor core <NUM> at a distance.

On the motor shaft <NUM>, bearings B1 and B1 are extrapolated and fixed on both sides of the rotor core <NUM>.

The bearing B1 located on one end 20a side of the motor shaft <NUM> from the rotor core <NUM> (right side in the figure) is supported by the inner circumference of the motor supporting portion <NUM> of the third box <NUM>. The other bearing B1 located on the other end 20b side is supported by the inner circumference of the cylindrical motor supporting portion <NUM> of the second box <NUM>.

The motor supporting portions <NUM> and <NUM> are arranged along the inner diameter of the coil ends 253a and 253b described later. The motor supporting portions <NUM> and <NUM> are arranged facing each other with a gap in the X-axis direction of the rotation shaft between one end portion 21a and the other end portion 21b of the rotor core <NUM>.

The rotor core <NUM> is formed by stacking multiple silicon steel plates. Each silicon steel plate is extrapolated onto the motor shaft <NUM> in a state where relative rotation with the motor shaft <NUM> is regulated.

From the X-axis direction of rotation of the motor shaft <NUM>, the silicon steel plates form a ring shape. North and south pole magnets (not shown) are alternately provided in the circumferential direction around the rotation axis X on the outer circumference side of the silicon steel plates.

The stator core <NUM> surrounding the outer circumference of the rotor core <NUM> is formed by laminating multiple electromagnetic steel plates. The stator core <NUM> is fixed to the inner circumference of the cylindrical support wall portion <NUM> of the first box <NUM>.

Each of the electromagnetic steel plates has a yoke portion <NUM>, a teeth portion <NUM>, and a coil <NUM>. The yoke portion <NUM> is ring-shaped and is fixed to the inner circumference of the support wall portion <NUM>. The teeth portion <NUM> protrudes from the inner circumference of the yoke portion <NUM> towards the rotor core <NUM>.

For example, coil <NUM> is formed by winding a winding (not shown) across multiple teeth portions <NUM>. Known copper wire or the like can be used for the winding that forms the coil <NUM>. The coil <NUM> may be configured as a distributed winding wound around each of the multiple teeth portions <NUM> protruding towards the rotor core <NUM>, or as a concentrated winding.

In the stator core <NUM>, the length of the coil <NUM> in the direction of the rotation axis X is set to be longer than that of the rotor core <NUM>. The stator core <NUM> has coil ends 253a and 253b located at both ends of the coil <NUM> in the direction of the rotation axis X, which protrude further in the direction of the rotation axis X than the rotor core <NUM>. The coil ends 253a and 253b have a symmetrical shape across the teeth portion <NUM>.

An opening 120a is provided in the wall portion <NUM> (motor supporting portion <NUM>) of the second box <NUM>. The other end 20b of the motor shaft <NUM> penetrates the opening 120a towards the differential mechanism <NUM> side (left side in the figure) and is located inside the fourth box <NUM>.

The other end 20b of the motor shaft <NUM> faces the side gear 54A with a gap in the direction of the rotation axis X inside the fourth box <NUM>, as will be described later.

As shown in <FIG>, the motor shaft <NUM> has a step portion <NUM> in the region located inside the fourth box <NUM>. The step portion <NUM> is located near the motor supporting portion <NUM>. A lip seal RS supported by the inner circumference of the motor supporting portion <NUM> contacts the outer circumference of the area between the step portion <NUM> and the bearing B1.

The lip seal RS divides the motor chamber Sa that accommodates the motor <NUM> and the gear chamber Sb inside the fourth box <NUM>.

Oil OL for lubricating the planetary reduction gear <NUM> and the differential mechanism <NUM> is sealed inside the fourth box <NUM> on the inner diameter side (see <FIG>).

The lip seal RS is provided to prevent the flow of oil OL into the motor chamber Sa.

As shown in <FIG>, the region of the motor shaft <NUM> from the step portion <NUM> to the vicinity of the other end 20b is a fitting portion <NUM> with splines provided on the outer circumference.

The park gear <NUM> and the sun gear <NUM> are spline-fitted on the outer circumference of the fitting portion <NUM>.

One side surface of the park gear <NUM> is in contact with the step portion <NUM> in the direction of the rotation axis X (on the right side in the figure). One end 410a of the cylindrical base <NUM> of the sun gear <NUM> contacts the other side surface of the park gear <NUM> in the direction of the rotation axis X (on the left side in the figure).

A nut N is press-fitted from the direction of the rotation axis X on the other end 410b of the base <NUM>. The nut N is screwed onto the other end 20b of the motor shaft <NUM>.

The sun gear <NUM> and the park gear <NUM> are provided to be unable to rotate relative to the motor shaft <NUM>, being sandwiched between the nut N and the step portion <NUM>.

The sun gear <NUM> has teeth portion <NUM> on the outer circumference of the other end 20b side of motor shaft <NUM>. A stepped pinion gear <NUM> with a large diameter gear portion <NUM> as a pinion gear is engaged with the teeth portion <NUM> on the outer circumference.

Stepped pinion gear <NUM> has a large diameter gear portion <NUM> that engages with the sun gear <NUM>, and a small diameter gear portion <NUM> that is smaller than the large diameter gear portion <NUM>.

The stepped pinion gear <NUM> is a gear component in which the large diameter gear portion <NUM> and the small diameter gear portion <NUM> are provided integrally and arranged parallel to the rotation axis X1 direction.

The large diameter gear portion <NUM> is formed with a larger outer diameter R1 than the outer diameter R2 of the small diameter gear portion <NUM>.

The stepped pinion gear <NUM> is provided in the direction along the axis X1, and the large diameter gear portion <NUM> is located on the motor <NUM> side (right side in the figure) of the small diameter gear portion <NUM>.

The outer circumference of the small diameter gear portion <NUM> is engaged with the inner circumference of the ring gear <NUM>. The ring gear <NUM> forms a ring shape that surrounds the rotation axis X at a distance. A plurality of engaging teeth <NUM> protruding radially outward are provided on the outer circumference of the ring gear <NUM>. The plurality of engaging teeth <NUM> are provided at intervals in the circumferential direction around the rotation axis X.

The engaging teeth <NUM> are provided on the outer circumference of the ring gear <NUM>. Teeth portion 146a is provided on the support wall portion <NUM> of the fourth box <NUM>. The engaging teeth <NUM> are spline-fitted to the teeth portion 146a. The rotation of the ring gear <NUM> around the rotation axis X is restricted.

The stepped pinion gear <NUM> has a through hole <NUM>. The through hole <NUM> penetrates the inner diameter side of the large diameter gear portion <NUM> and the small diameter gear portion <NUM> in the axial direction X1. The pinion shaft <NUM> is inserted into the through hole <NUM>. Needle bearings NB and NB are provided on the outer circumference of the pinion shaft <NUM>. The stepped pinion gear <NUM> is rotatably supported via the needle bearings NB and NB.

One needle bearing NB on one side (right side in the figure) in the direction of the rotation axis X supports the inner circumference of the large diameter gear portion <NUM>. The other needle bearing NB on the other side (left side in the figure) in the direction of the rotation axis X supports the inner circumference of the small diameter gear portion <NUM>. An intermediate spacer MS is interposed between the needle bearings NB and NB.

As shown in <FIG>, the inside of the pinion shaft <NUM> has internal oil passages 440A and 440B. The axial internal oil passage 440A extends from one end 44a (right side in the figure) of the pinion shaft <NUM> to the inner diameter side of the large diameter gear portion <NUM> along the axis X1. The axial internal oil passage 440B extends from the other end 44b (left side in the figure) of the pinion shaft <NUM> to the inner diameter side of the small diameter gear portion <NUM> along the axis X1.

The pinion shaft <NUM> has oil holes <NUM>, <NUM>, <NUM>, and <NUM>. The oil holes <NUM> and <NUM> communicate the axial internal oil passage 440A with the outer circumference of the pinion shaft <NUM>. The oil holes <NUM> and <NUM> communicate the axial internal oil passage 440B with the outer circumference of the pinion shaft <NUM>.

Oil hole <NUM> opens in the region where the needle bearing NB is provided, and the needle bearing NB supports the inner circumference of the large diameter gear portion <NUM>. In the pinion shaft <NUM>, the oil hole <NUM> opens in the region where the stepped pinion gear <NUM> is extrapolated. Oil hole <NUM> opens in the gap CL1 in the axial direction of the large diameter gear portion <NUM> and the opposing surface 61b of the case member <NUM> of the differential case <NUM>.

Oil OL scraped up by the differential case <NUM> described later flows into the oil hole <NUM>. The oil OL that flows into the oil hole <NUM> flows into the axial internal oil passage 440A of the pinion shaft <NUM>. The oil OL that flows into the axial internal oil passage 440A is discharged radially outward from the oil hole <NUM>. The oil OL discharged from the oil hole <NUM> lubricates the needle bearing NB extrapolated on the pinion shaft <NUM>.

Furthermore, the oil hole <NUM> opens into the region where the needle bearing NB supporting the inner circumference of the small diameter gear portion <NUM> is provided. In the pinion shaft <NUM>, the oil hole <NUM> opens into the region where the stepped pinion gear <NUM> is extrapolated.

The oil hole <NUM> communicates the axial internal oil passage 440B with the outer circumference of the pinion shaft <NUM>. The oil hole <NUM> opens into the gap CL2 between the side wall 432a of the small diameter gear portion <NUM> in the X1 axis direction and the plate portion <NUM> of the case member <NUM> described later.

Oil OL scraped up by the differential case <NUM> described later flows into the gap CL2 and flows toward the outer diameter side. The oil OL that flows from the gap CL2 into the oil hole <NUM> flows into the axial internal oil passage 440B of the pinion shaft <NUM>. The oil OL that flows into the axial internal oil passage 440B is discharged radially outward from the oil hole <NUM>. The oil OL discharged from the oil hole <NUM> lubricates the needle bearing NB extrapolated on the pinion shaft <NUM>. In other words, the gap CL2 functions as an oil path that leads the oil OL scraped up by the differential case <NUM> to the pinion shaft <NUM>.

As shown in <FIG>, the pinion shaft <NUM> has a first shaft portion <NUM> on one end 44a side (right side in <FIG>) in the longitudinal direction. The first shaft portion <NUM> is a region that protrudes from the stepped pinion gear <NUM>. The first shaft portion <NUM> is supported by a support hole 61a provided in the case member <NUM> of the differential case <NUM>.

The pinion shaft <NUM> has a second shaft portion <NUM> on the other end 44b side (left side in <FIG>) in the longitudinal direction. The second shaft portion <NUM> is also a region that protrudes from the stepped pinion gear <NUM>. The second shaft portion <NUM> is supported by a support hole 68a provided in the case member <NUM> of the differential case <NUM>. As will be described in detail later, the second shaft portion <NUM> is press-fitted into the support hole 68a. The second shaft portion <NUM> is supported so as to be unable to rotate relative to the case member <NUM>.

Here, the first shaft portion <NUM> is a region on the end 44a side of the pinion shaft <NUM> where the stepped pinion gear <NUM> is not extrapolated. The second shaft portion <NUM> is a region on the other end 44b side of the pinion shaft <NUM> where the stepped pinion gear <NUM> is not extrapolated.

In the pinion shaft <NUM>, the length in the axial direction X1 of the second shaft portion <NUM> is longer than that of the first shaft portion <NUM>.

The main structure of the differential mechanism <NUM> will be described below.

<FIG> is a perspective view around the differential case <NUM> of the differential mechanism <NUM>.

<FIG> is an exploded perspective view around the differential case <NUM> of the differential mechanism <NUM>, exposing the inside of the differential mechanism <NUM> by omitting one stepped pinion gear <NUM>.

As shown in <FIG>, the differential case <NUM> as a case accommodates the differential mechanism <NUM>. The differential case <NUM> is formed by assembling the case member <NUM> (second case member) and the case member <NUM> (first case member) in the direction of the rotation axis X. The case member <NUM> of the differential case <NUM> functions as a carrier supporting the pinion shaft <NUM> of the planetary reduction gear <NUM>.

As shown in <FIG>, three pinion mate gears <NUM> and pinion mate shaft <NUM> are provided between the case members <NUM> and <NUM> of the differential case <NUM>. The pinion mate shaft <NUM> functions as a support shaft for supporting the pinion mate gears <NUM>.

The pinion mate shaft <NUM> has three shaft members <NUM> provided at equal intervals in the circumferential direction around the rotation axis X (see <FIG>).

The inner end of each shaft member <NUM> is connected to a central member <NUM> arranged on the rotation axis X. That is, the shaft members <NUM> are arranged radially with respect to the central member <NUM>. The pinion mate shaft <NUM> may be formed integrally with the central member <NUM> and the shaft members <NUM>.

Each of the pinion mate gears <NUM> is extrapolated on each shaft member <NUM>. Each of the pinion mate gears <NUM> is in contact with the central member <NUM> from the radially outer side of the rotation axis X. In this state, each of the pinion mate gears <NUM> is rotatably supported by the shaft members <NUM>.

As shown in <FIG>, spherical washers <NUM> are extrapolated on the shaft members <NUM>. The spherical washers <NUM> are in contact with the spherical outer periphery of the pinion mate gears <NUM>.

In the differential case <NUM>, the side gear 54A is located on one side of the central member <NUM> in the direction of the rotation axis X, and the side gear 54B is located on the other side. The side gear 54A is rotatably supported by the case member <NUM>, and the side gear 54B is rotatably supported by the case member <NUM>.

The side gear 54A engages with three pinion mate gears <NUM> from one side in the direction of the rotation axis X. The side gear 54B engages with three pinion mate gears <NUM> from the other side in the direction of the rotation axis X.

<FIG> are diagrams explaining the case member <NUM>.

<FIG> is a perspective view of the case member <NUM> of the differential mechanism <NUM> as viewed from the side of the case member <NUM>.

<FIG> is a plan view of the case member <NUM> of the differential mechanism <NUM> as viewed from the side of the case member <NUM>.

In <FIG> and <FIG>, cross-hatching is added to the plate portion <NUM> for easier viewing.

<FIG> is a schematic view of the A-A cross-section in <FIG>, showing the arrangement of the shaft member <NUM> of the pinion mate shaft <NUM> in dotted lines.

<FIG> is an arrow diagram of the A-A direction in <FIG>.

<FIG> is a schematic view of the A-A cross-section in <FIG>, omitting the plate member <NUM> and the connecting beam <NUM> on the back side of the paper. <FIG> shows the side gear 54A, stepped pinion gear <NUM>, and drive shaft 9A in dotted lines.

<FIG> shows the upper region of the rotation axis X in <FIG>. The stepped pinion gear <NUM> is shown in solid lines.

As shown in <FIG> and <FIG>, the case member <NUM> has a ring-shaped base <NUM>. The base <NUM> is a plate member having a thickness W61 in the direction of the rotation axis X.

As shown in <FIG>, an opening <NUM> is provided in the center of the base <NUM>. A cylindrical tubular wall portion <NUM> surrounding the opening <NUM> is provided on the base <NUM>. The cylindrical tubular wall portion <NUM> is provided on the side opposite (right side in <FIG>) to the case member <NUM> of the base <NUM>. The outer circumference of the cylindrical tubular wall portion <NUM> is supported by a plate member <NUM> via a bearing B3 (see <FIG>).

The base <NUM> is provided with three connecting beams <NUM> that extend toward the case member <NUM> side. The connecting beams <NUM> are provided on the surface of the base <NUM> on the case member <NUM> side (the left side in <FIG>).

The three connecting beams <NUM> are provided at equal intervals in the circumferential direction around the rotation axis X (see <FIG> and <FIG>).

As shown in <FIG>, the connecting beams <NUM> have a base <NUM> that is connected to the base <NUM>. The base <NUM> extends in a direction orthogonal to the base <NUM>. The connecting beams <NUM> have a connecting portion <NUM> that is connected to the case member <NUM> side of the base <NUM> (the left side in the figure). The connecting portion <NUM> is wider than the base <NUM>. The connecting portion <NUM> has a greater width in the circumferential direction around the rotation axis X than the base <NUM>.

On the inner diameter side of the connecting portion <NUM>, a circular space is formed when viewed from the direction of the rotation axis X. As shown in <FIG>, the central member <NUM> of the pinion mate shaft <NUM>, the pinion mate gear <NUM>, and the spherical washer <NUM> are accommodated in this space. The spherical washer <NUM> is positioned on the outer circumference of the pinion mate gear <NUM>, and the central member <NUM> is positioned on the inner circumference of the pinion mate gear <NUM>.

Connecting member <NUM> is provided at equal intervals in the circumferential direction around the rotation axis X, as shown in <FIG>. Three plate portions <NUM> are arranged between the connecting portions <NUM>. The plate portions <NUM> extend along the circumferential direction around the rotation axis X and connect the adjacent connecting portions <NUM>. The plate portions <NUM> have an arc shape as viewed from the direction of the rotation axis X. As shown in <FIG>, the plate portions <NUM> protrude toward the case member <NUM> side (left side in the figure) more than the connecting portions <NUM>. The plate portions <NUM> face the base <NUM> with a gap. The stepped pinion gear <NUM> and pinion shaft <NUM> are accommodated in this gap (see <FIG>).

As shown in <FIG>, a step portion 63a is formed along the circumferential direction around the rotation axis X on the outer peripheral surface of the base <NUM>. As shown in <FIG>, the case member <NUM> is divided into a first portion 6A on the case member <NUM> side (left side in the figure) and a second portion 6B on the base <NUM> side (right side in the figure) separated by the step portion 63a.

The diameter of the outer peripheral surface of the second portion 6B is larger than that of the outer peripheral surface of the first portion 6A. The weight of the case member <NUM> is reduced by making the thickness of the first portion 6A in the radial direction of the rotation axis X smaller than the thickness of the second portion 6B. The step portion 63a shown in <FIG> is formed near the center of the rotation axis X of the base <NUM> in the X direction. The position where the step portion 63a is formed can be changed appropriately.

As shown in <FIG>, a recess <NUM> is provided at the center of the direction of the rotation axis X in the circumferential direction of the connecting portion <NUM>. As shown in <FIG>, the recess <NUM> is concave toward the base <NUM> side with respect to the plate portion <NUM>. The recess <NUM> has a bottom surface portion <NUM> and a side wall portion <NUM>. The arc-shaped bottom surface portion <NUM> extends along the circumferential direction of the rotation axis X of the recess <NUM>. The side wall portion <NUM> extends in the X direction toward the plate portion <NUM> from the bottom surface portion <NUM>.

A groove portion <NUM> extending in the radial direction of the rotation axis X is formed at the boundary between the bottom surface portion <NUM> and the side wall portion <NUM>. The bottom surface portion <NUM> of the recess <NUM> is a surface extending in a direction perpendicular to the rotation axis X. A support groove <NUM> (second cutout portion) for supporting the shaft member <NUM> of the pinion mate shaft <NUM> is provided on the bottom surface portion <NUM>.

As shown in <FIG>, the support groove <NUM>, when viewed from the direction of the rotation axis X, is formed linearly along the radius line L of the ring-shaped base <NUM>. The support groove <NUM> transverses the central portion of the recess <NUM> in the circumferential direction of the rotation axis X from the inner diameter side to the outer diameter side.

As shown in <FIG>, the support groove <NUM> has a semi-circular shape. The support groove <NUM> is formed by cutting out the bottom surface portion <NUM> along the outer diameter of the shaft member <NUM> of the pinion mate shaft <NUM>. The support groove <NUM> is formed to a depth capable of accommodating half of the cylindrical shaft member <NUM>. That is, the support groove <NUM> is formed to a depth corresponding to half the diameter Da (=Da/<NUM>) of the shaft member <NUM>.

An arc portion <NUM> is formed on the inner diameter side (rotation axis X side) of the connecting portion <NUM>, along the outer circumference of the pinion mate gear <NUM>.

In the arc portion <NUM>, the outer circumference of the pinion mate gear <NUM> is supported by a spherical washer <NUM>.

In the arc portion <NUM>, an oil groove <NUM> is provided in the direction along the above-mentioned radius line L. The oil groove <NUM> is provided in the range from the support groove <NUM> that supports the shaft member <NUM> to the gear support portion <NUM> fixed to the inner circumference of the connecting portion <NUM>.

The gear support portion <NUM> is connected to the boundary between the base <NUM> and the connecting portion <NUM>. The gear support portion <NUM> is provided in a direction perpendicular to the rotation axis X and has a through hole <NUM> in the central portion.

As shown in <FIG>, the outer circumference of the gear support portion <NUM> is connected to the inner circumference of three connecting portions <NUM>. In this state, the center of the through hole <NUM> is located on the rotation axis X.

As shown in <FIG> and <FIG>, in the gear support portion <NUM>, a recess <NUM> is provided on the side opposite to the base <NUM> (left side in the figure). The recess <NUM> surrounds the through hole <NUM>. A ring-shaped washer <NUM> is accommodated in the recess <NUM>. The washer <NUM> supports the back surface of the side gear 54A.

The back surface of the side gear 54A has a cylindrical tubular wall portion <NUM>, and the washer <NUM> is extrapolated on the tubular wall portion <NUM>.

From the X-axis direction of the rotation axis, three oil grooves <NUM> are provided on the side of the recess <NUM> in the gear support portion <NUM>. The oil grooves <NUM> are provided at predetermined intervals in the circumferential direction around the X-axis.

The oil grooves <NUM> extend from the inner circumference to the outer circumference of the gear support portion <NUM> along the radius line L mentioned above. The oil grooves <NUM> are in communication with the oil groove <NUM> on the arc portion <NUM> side mentioned above.

As shown in <FIG> and <FIG>, the support hole 61a for the pinion shaft <NUM> is opened in the base <NUM>. The support hole 61a opens into the region between the connecting beams <NUM>, <NUM> arranged at intervals in the circumferential direction around the X-axis.

The boss portion <NUM> surrounding the support hole 61a is provided in the base <NUM>. The washer Wc (see <FIG>) extrapolated from the pinion shaft <NUM> is in contact with the boss portion <NUM> from the X-axis direction of rotation.

In the base <NUM>, an oil groove <NUM> is provided in the range from the central opening <NUM> to the boss portion <NUM>.

As shown in <FIG>, the oil groove <NUM> is formed in a tapered shape with a gradually narrowing width in the circumferential direction around the X-axis as it approaches the boss portion <NUM>. The oil groove <NUM> is in communication with the oil groove <NUM> provided in the boss portion <NUM>.

In the connecting portion <NUM>, bolt holes <NUM>, <NUM> are provided on both sides of the support groove <NUM>.

As shown in <FIG>, the connecting portion <NUM> on the case member <NUM> side is joined to the connecting portion <NUM> on the case member <NUM> from the X-axis direction of rotation. The case members <NUM> and <NUM> are joined to each other by bolts B (see <FIG>). The bolt B penetrates through the connecting portion <NUM> on the case member <NUM> side and is screwed into the bolt hole <NUM>.

As shown in <FIG>, the plate portion <NUM> is composed of an arc-shaped base <NUM> and an outer circumferential wall portion <NUM> provided on the outer peripheral edge of the base <NUM> when viewed from the X-axis direction of rotation.

As shown in <FIG>, the base <NUM> is a plate member arranged along the thickness direction in the X-axis direction of rotation. One end surface 680a and the other end surface 680b of the base <NUM> in the X-axis direction of rotation are flat surfaces perpendicular to the X-axis of rotation. The outer circumferential wall portion <NUM> protrudes from one end surface 680a of the base <NUM> in the X-axis direction of rotation.

As shown in <FIG>, the outer circumferential wall portion <NUM> is formed over the entire length of the base <NUM> in the circumferential direction around the rotation axis X when viewed from the X-axis direction. The inner circumferential surface 681a of the outer circumferential wall portion <NUM> is formed to overlap with a virtual circle Im1 having a diameter D1. The inner circumferential surface 680c of the base <NUM> is formed to overlap with a virtual circle Im2 having a diameter D2.

As shown in <FIG>, a support hole 68a penetrating the base <NUM> in the X-axis direction of rotation is formed in the plate portion <NUM>. The support hole 68a and the support hole 61a are concentrically arranged along the axis X1 parallel to the rotation axis X.

As shown in <FIG>, the support hole 68a is formed in the central portion of the base <NUM> in the circumferential direction around the rotation axis X.

Note that, as will be described later in detail, the region on the inner diameter side of the support hole 68a in the base <NUM> of the plate portion <NUM> forms an oil receiving portion <NUM> (see <FIG>). The oil receiving portion <NUM> receives oil OL scraped up by the rotation of differential case <NUM>.

In the following description, the end face 680a, the other end face 680b, and the inner circumferential surface 680c of the base <NUM> on the inner diameter side of the support hole 68a are also referred to as the end face 680a, the other end face 680b, and the inner circumferential surface 680c of the oil receiving portion <NUM>.

As shown in <FIG>, a recess <NUM> is provided on the inner circumferential surface 680c of the oil receiving portion <NUM>. The recess <NUM> is formed by cutting out the central portion of the circumferential direction around the rotation axis X of the inner circumferential surface 680c.

When viewed from the direction of the rotation axis X, the recess <NUM> is open towards the radial inner diameter side. The recess <NUM> has inclined surfaces 683a and 683b. The inclined surfaces 683a and 683b have a decreasing circumferential opening width W68 towards the outer diameter side from the inner circumferential surface 680c. The inclined surface 683a and the inclined surface 683b of the recess <NUM> intersect at vertex P. The vertex P is located on a diameter line Lr passing through the rotation axis X and the axis line X1.

As shown in <FIG>, the inner circumferential surface 680c and the recess <NUM> of the oil receiving portion <NUM> are inclined to be located on the radial outer side as they go from one end surface 680a to the other end surface 680b in the direction of the rotation axis X.

The inclined surfaces 683a and 683b of the recess <NUM> are also inclined to be located on the radial outer side as they go from one end surface 680a to the other end surface 680b in the direction of the rotation axis X.

As shown in <FIG>, an oil groove <NUM> is formed on the other end face 680b of the oil receiving portion <NUM> in the direction of the rotation axis X. The oil groove <NUM> connects the recess <NUM> and the support hole 68a. The oil groove <NUM> extends linearly along the diameter line Lr from the vertex P of the recess <NUM> (see <FIG>).

As shown in <FIG>, the assembly of the stepped pinion gear <NUM> to the case member <NUM> is carried out by placing the stepped pinion gear <NUM> in the space between the base <NUM> and the plate portion <NUM> in the direction of the rotation axis X. The pinion shaft <NUM> is inserted from the support hole 61a side (arrow direction in the figure). A washer Wc is interposed between the large diameter gear portion <NUM> and the base <NUM> in the direction of the rotation axis X. A washer Wc is also interposed between the small diameter gear portion <NUM> and the base <NUM>.

One end 44a and the other end 44b of the pinion shaft <NUM> are supported by support holes 61a and 68a, respectively. The diameter of the support hole 61a is set slightly larger than the outer diameter of the pinion shaft <NUM>. The diameter of the support hole 68a is set to approximately match the outer diameter of the pinion shaft <NUM>. At the other end 44b of the pinion shaft <NUM>, it is press-fitted into the support hole 68a. As a result, the pinion shaft <NUM> is fixed to the case member <NUM> so as to be unable to rotate relative to it. The stepped pinion gear <NUM> is extrapolated onto the pinion shaft <NUM> and is supported so as to be rotatable around the axis X1 by the pinion shaft <NUM>.

As shown in the enlarged area of <FIG>, assemble the stepped pinion gear <NUM> to the case member <NUM>. The other end face 680b of the base <NUM> faces the side wall 432a of the small diameter gear portion <NUM> via the washer Wc in the direction of the rotation axis X.

In the area of the base <NUM> where the oil groove <NUM> of the oil receiving portion <NUM> is formed, a gap CL2 is formed. The gap CL2 is formed between the oil groove <NUM> in the direction of the rotation axis X and the side wall 432a of the small diameter gear portion <NUM>, with the washer Wc sandwiched in between. The oil hole <NUM> of the pinion shaft <NUM> opens into the gap CL2.

As shown in the enlarged area of <FIG>, the case member <NUM> (shown in a virtual line) is attached to the case member <NUM> from the plate portion <NUM> side in the direction of the rotation axis X.

<FIG> are parts diagrams illustrating the case member <NUM>.

<FIG> is a perspective view of the case member <NUM> viewed from the opposite side of the case member <NUM>.

<FIG> is a plan view of the case member <NUM> viewed from the opposite side of the case member <NUM>.

<FIG> is a perspective view of the case member <NUM> viewed from the side of the case member <NUM>.

<FIG> is a plan view of the case member <NUM> viewed from the side of the case member <NUM>. In <FIG>, the guide portion <NUM> is hatched to make its position easier to understand.

<FIG> is a schematic diagram of the A-A cross-section in <FIG>. The arrangement of the pinion mate gear <NUM> is shown in dashed lines in <FIG>. In <FIG>, the boundary between the oil hole <NUM> and the guide portion <NUM> is shown in broken lines to make it easier to understand.

<FIG> is an A-A arrow view of <FIG>. Cross-hatching is used in <FIG> to make the position of the guide portion <NUM> easier to understand.

<FIG> is a schematic diagram of the A-A cross-section in <FIG>. The illustration of the connecting portion <NUM> on the far side of the page is omitted in <FIG>. In <FIG>, the stepped pinion gear <NUM>, plate portion <NUM>, side gear 54B, and drive shaft 9B are shown in dashed lines.

<FIG> is a schematic diagram of the A-A cross-section in <FIG>.

As shown in <FIG>, the case member <NUM> has a ring-shaped base <NUM> (plate) when viewed from the direction of the rotation axis X.

The base <NUM> is a plate member having a thickness W71 (see <FIG>) in the direction of the rotation axis X. A through-hole <NUM> is provided in the central portion of the base <NUM>. The through-hole <NUM> passes through the base <NUM> in the thickness direction. The diameter (2R4, see <FIG>) of the outer circumferential surface 71c of the base <NUM> is slightly smaller than the diameter D1 of a virtual circle Im1 (see <FIG>) (2R4 < D1). The virtual circle Im1 is formed along the inner circumferential surface 681a of the outer circumferential wall portion <NUM> of the plate portion <NUM> as described above.

As shown in <FIG>, one end surface 71a and the other end surface 71b of the base <NUM> in the direction of the rotation axis X are flat surfaces perpendicular to the rotation axis X. On one end face 71a of the base <NUM>, a tubular wall portion <NUM> and a guide portion <NUM> (the second guide portion) are provided. The tubular wall portion <NUM> surrounds a through-hole <NUM>, and the guide portion <NUM> surrounds the tubular wall portion <NUM>. As shown in <FIG>, the guide portion <NUM> is annular when viewed from the direction of the rotation axis X.

As shown in <FIG>, three ribs <NUM> are provided on the inner diameter side of the guide portion <NUM> of the base <NUM>. The three ribs <NUM> are provided at intervals in the circumferential direction around the rotation axis X. These ribs <NUM> are formed on one end face 71a of the base <NUM>, and extend linearly in the radial direction of the rotation axis X. The ribs <NUM> are provided so as to span across the outer diameter side guide portion <NUM> and the inner diameter side tubular wall portion <NUM>.

As shown in <FIG>, oil holes <NUM> (openings) penetrating through the base <NUM> in the thickness direction are provided between the three ribs <NUM> arranged in the circumferential direction around the rotation axis X. The oil holes <NUM> are opened on the outer and inner sides of the differential case <NUM> in the direction of the rotation axis X.

In addition, three ribs <NUM> are provided on the outer diameter side of the guide portion <NUM> at the base <NUM>. The three ribs <NUM> are provided with intervals in the circumferential direction around the rotation axis X. These ribs <NUM> are formed on one end surface 71a of the base <NUM>. The ribs <NUM> extend linearly in the radial direction of the rotation axis X from the guide portion <NUM> toward the outer circumferential surface 71c of the base <NUM>.

Bolt accommodating portions <NUM>, <NUM>, which are recessed toward the back of the paper, are provided on the base <NUM> between adjacent ribs <NUM>. These bolt accommodating portions <NUM>, <NUM> are provided in positions that are symmetric with respect to a radius line L. The bolt accommodating portion <NUM> is opened on the outer circumferential surface 71c of the base <NUM>.

A bolt insertion hole <NUM> is opened inside the bolt accommodating portion <NUM>. The insertion hole <NUM> penetrates through the base <NUM> in the thickness direction (direction of rotation axis X).

In the base <NUM>, the three ribs <NUM> are formed on the outer diameter side of the oil holes <NUM> in the radial direction of the rotation axis X.

As shown in <FIG>, oil holes <NUM> in the case member <NUM> are provided at intervals in the circumferential direction around the rotation axis X.

As shown in the enlarged region of <FIG>, the oil holes <NUM> have a substantially rectangular shape when viewed from the direction of the rotation axis X. The oil holes <NUM> are composed of long sides 710a and 710b that extend along the circumferential direction around the rotation axis X, and short sides 710c and 710d that connect the end portions of these long-side portions 710a and 710b. In the oil holes <NUM>, the long-side portion 710a is positioned on the outer diameter side relative to the long-side portion 710b.

As shown in <FIG> and <FIG>, three guide portions <NUM> (first guide portions) are provided on the other end surface 71b on the case member <NUM> side at the base <NUM>. The three guide portions <NUM> surround oil holes <NUM>, and are arranged at intervals in the circumferential direction around the rotation axis X.

The guide portions <NUM> are continuous walls that surround the oil holes <NUM> and open toward the inner diameter side. Specifically, as shown in the enlarged area of <FIG>, each guide portion <NUM> includes a long wall portion <NUM> that extends along the long side portion 710a of the oil hole <NUM>, and short wall portions <NUM> and <NUM> that extend along the short side portions 710c and 710d of the oil hole <NUM>. The long wall portion <NUM> and the short wall portions <NUM> and <NUM> are formed integrally.

As shown in <FIG>, the outer circumferential surface 781b of the long wall portion <NUM> overlaps with a virtual circle Im3 having a diameter D4. The diameter D4 of the virtual circle Im3 is smaller than the diameter D2 of a virtual circle Im2 (see <FIG>). The virtual circle Im2 extends along the inner circumferential surface 680c of the base <NUM> in the plate portion <NUM> of the case member <NUM>, as mentioned above.

As shown in <FIG>, when viewed from the direction of the rotation axis X, the long wall portion <NUM> of the guide portions <NUM> is a curved wall extending in the circumferential direction around the rotation axis X. The short wall portions <NUM> and <NUM> extend radially inward from both ends of the long wall portion <NUM> in the circumferential direction around the rotation axis X. The short wall portions <NUM> and <NUM> extend linearly along lines Lm2 and Lm3, respectively. The lines Lm2 and Lm3 are parallel to a line Lm1. The line Lm1 is a straight line passing through the rotation axis X and the midpoint C of the inner circumferential surface 781a of the long wall portion <NUM> in the circumferential direction around the rotation axis X.

In the enlarged area of <FIG>, the boundary between the oil hole <NUM> and the guide portions <NUM> is shown with a broken line.

As shown in the enlarged area of <FIG>, the inner circumferential surface 781a of the long wall portion <NUM> and the inner circumferential surfaces 783a and 784a of the short wall portions <NUM> and <NUM> are located in front of the broken line relative to the paper surface. The long side portion 710a of the oil hole <NUM> and the short wall portions <NUM> and <NUM> are located behind the broken line relative to the paper surface. The inner circumferential surface 781a is connected to the long side portion 710a without any step. The inner circumferential surfaces 783a and 784a are connected to the short side portions 710d and 710c, respectively, without any step.

As shown in <FIG>, the guide portions <NUM> and <NUM> extend in a direction away from the base <NUM> in the direction of the rotation axis X. When viewed radially from the rotation axis X, the inner circumferential surface <NUM> of the guide portion <NUM> is a flat surface parallel to the rotation axis X. The long-side portion 710a of the oil hole <NUM> is connected to the inner circumferential surface <NUM> of the guide portion <NUM> on the end surface 71a side of the base <NUM> in the direction of the rotation axis X. The long-side portion 710a of the oil hole <NUM> is an inclined surface. The long-side portion 710a is inclined so as to be positioned on the outer diameter side as it moves away from the inner circumferential surface <NUM> of the guide portion <NUM> in the direction of the rotation axis X. The long-side portion 710a of the oil hole <NUM> is connected to the inner circumferential surface 781a of the long wall portion <NUM> of the guide portion <NUM> on the other end surface 71b side of the base <NUM> in the direction of the rotation axis X.

The inner circumferential surface 781a of the long wall portion <NUM> of the guide portion <NUM> is an inclined surface. The inner circumferential surface 781a is inclined so as to be positioned on the outer diameter side as it moves away from the inner circumferential surface <NUM> of the guide portion <NUM> in the direction of the rotation axis X. The inclination angle of the inner circumferential surface 781a of the long wall portion <NUM> is the same as the inclination angle of the long-side portion 710a of the oil hole <NUM>.

As shown in <FIG> and <FIG>, three connecting portions <NUM> (protrusions) are provided on the other end surface 71b of the base <NUM> on the case member <NUM> side.

The connecting portions <NUM> are provided at equal intervals in the circumferential direction around the rotation axis X. As shown in <FIG>, the connecting portions <NUM> have a leading end surface <NUM> protruding toward the case member <NUM> side. The connecting portions <NUM> also have side wall portions <NUM> connecting both end portions in the circumferential direction around the rotation axis X of the leading end surface <NUM> and the base <NUM>.

As shown in <FIG> and <FIG> to be described later, the connecting portions <NUM> have a circumferential width W2. The recess <NUM> of the connecting portion <NUM> on the case member <NUM> side has a circumferential width W1 (see <FIG>). The width W2 is smaller than the width W1. The width W1 refers to the length from the side wall portion <NUM> connected to one end in the circumferential direction around the rotation axis X of the bottom surface portion <NUM> to the side wall portion <NUM> connected to the other end. The width W2 refers to the length from the side wall portion <NUM> connected to one end in the circumferential direction around the rotation axis X of the leading end surface <NUM> to the side wall portion <NUM> connected to the other end.

As shown in <FIG>, the leading end surface <NUM> of the connecting portions <NUM> is a curved surface extending along the circumferential direction of the rotation axis X when viewed from the direction of the rotation axis X. As shown in <FIG>, the side wall portion <NUM> extends from the leading end surface <NUM> toward the base <NUM> in the direction of the rotation axis X. The bolt insertion hole <NUM> opens in the leading end surface <NUM>, and one end of the bolt insertion hole <NUM> opens to the bolt accommodating portion <NUM> (see <FIG>), penetrating through the base <NUM> in the thickness direction (the direction of the rotation axis X). The other end of the penetration hole <NUM> opens in the leading end surface <NUM>. As shown in <FIG>, a support groove <NUM> (first cutout portion) is provided in the leading end surface <NUM>. The support groove <NUM> supports the pinion mate shaft <NUM>. The support groove <NUM> is formed between the bolt insertion holes <NUM> in the circumferential direction of the rotation axis X.

As shown in <FIG>, the support groove <NUM>, when viewed from the direction of the rotation axis X, is formed linearly along the radius line L of the base <NUM>. The support groove <NUM> is formed by crossing the connecting portion <NUM> from the inner diameter side to the outer diameter side.

The support groove <NUM> is semi-circular. The support groove <NUM> is formed by cutting out the leading end surface <NUM> along the outer diameter of the shaft member <NUM>.

As shown in <FIG>, the support groove <NUM> is formed at a depth that can accommodate half of the cylindrical shaft member <NUM>. That is, the support groove <NUM> is formed at a depth equivalent to half the diameter Da (=Da/<NUM>) of the shaft member <NUM>.

As shown in <FIG>, the outer circumferential surface 74a of the connecting portion <NUM> protrudes radially outward from the outer circumferential surface 71c of the base <NUM> in the direction of the rotation axis X. The outer circumferential surface 74a of the connecting portion <NUM> and the outer circumferential surface 71c of the base <NUM> are connected by a step portion <NUM>. That is, the step portion <NUM> is provided on the outer circumferential surface of the boundary between the connecting portion <NUM> and the base <NUM>. As shown in <FIG>, the outer circumferential surface 74a is located on the connecting portion <NUM> side of the step portion <NUM>, and the outer circumferential surface 71c is located on the base <NUM> side. The radius R3 of the outer circumferential surface 74a is longer than the radius R4 of the outer circumferential surface 71c. Here, R3 and R4 respectively denote the radius from the rotation axis X.

As shown in <FIG> and <FIG>, an arc portion <NUM> is provided on the inner diameter side (rotation axis X side) of the connecting portion <NUM>. The arc portion <NUM> follows the outer circumference of the pinion mate gear <NUM>.

In the arc portion <NUM>, the outer circumference of the pinion mate gear <NUM> is supported via a spherical washer <NUM> (see <FIG>).

In the arc portion <NUM>, an oil groove <NUM> is provided along the above-mentioned radius line L. The oil groove <NUM> is provided in the range from the support groove <NUM> of the shaft member <NUM> to the base <NUM> located on the inner circumference of the connecting portion <NUM>.

The oil groove <NUM> communicates with an oil groove <NUM> provided in the other end surface 71b of the base <NUM>. As shown in <FIG>, the oil groove <NUM> is provided along the radius line L when viewed from the direction of the rotation axis X. The oil groove <NUM> is formed up to the through-hole <NUM> provided in the base <NUM>. As shown in the magnified area below <FIG>, a ring-shaped washer <NUM> is placed on the other end surface 71b of the base <NUM>. The washer <NUM> supports the back surface of the side gear 54B. A cylindrical tubular wall portion <NUM> is provided on the back surface of the side gear 54B. The washer <NUM> is extrapolated to the tubular wall portion <NUM>.

As shown in <FIG>, an oil groove <NUM> is formed on the inner circumference of a tubular wall portion <NUM> surrounding the through-hole <NUM>. The oil groove <NUM> is formed at a position where it intersects with the oil groove <NUM>. On the inner circumference of the tubular wall portion <NUM>, the oil groove <NUM> is provided along the direction of the rotation axis X, over the entire length of the tubular wall portion <NUM> in the direction of the rotation axis X.

<FIG> is a parts diagram illustrating the assembly of the case members <NUM> and <NUM>.

<FIG> shows the state before the assembly of the case members <NUM> and <NUM>, while <FIG> shows the state after the assembly of the case members <NUM> and <NUM>. <FIG> show the differential case <NUM> viewed from the A-A direction in <FIG>. Hatching is applied to the connecting portions <NUM> and <NUM> for ease of viewing. The shaft member <NUM> of the pinion mate shaft <NUM> is shown in dashed lines in <FIG>.

As shown in <FIG>, the differential case <NUM> is constructed by assembling the case members <NUM> and <NUM> in the direction of the rotation axis X. That is, the direction of the rotation axis X follows the assembly direction of the differential case <NUM>. As shown in <FIG>, the connecting portion <NUM> (convex portion) of the case member <NUM> is inserted into the recess <NUM> of the connecting portion <NUM> of the case member <NUM>.

As shown in <FIG>, the length L2 of the side wall portion <NUM> of the case member <NUM> in the direction of the rotation axis X matches the length L1 of the side wall portion <NUM> of the case member <NUM> in the direction of the rotation axis X. Therefore, as shown in <FIG>, the leading end surface <NUM> of the connecting portion <NUM> inserted into the recess <NUM> contacts the bottom surface portion <NUM>. This determines the position of the case members <NUM> and <NUM> in the direction of the rotation axis X.

As shown in <FIG>, the outer circumferential surface 71c of the base <NUM> of the case member <NUM> is fitted into the inner circumferential surface 681a of the outer circumferential wall portion <NUM> on the plate portion <NUM> of the case member <NUM>. As shown in <FIG>, the case members <NUM> and <NUM> are concentrically arranged on the rotation axis X.

As mentioned above, the case members <NUM> and <NUM> are joined to each other by bolts B (see <FIG>) that penetrate through the connecting portion <NUM> on the side of the case member <NUM> and are screwed into bolt holes <NUM> and <NUM> on the side of the case member <NUM>.

As shown in <FIG>, the support grooves <NUM> of the bottom surface portion <NUM> and <NUM> of the leading end surface <NUM> are formed at positions that overlap when viewed from the direction of the rotation axis X. When the bottom surface portion <NUM> and the leading end surface <NUM> are in contact with each other, the semi-circular support grooves <NUM> and <NUM> face each other. The support grooves <NUM> and <NUM> are symmetrical with respect to a line that passes through the bottom surface portion <NUM> and the leading end surface <NUM>. The opening of the support grooves <NUM> and <NUM> communicate with each other, forming a circular hole along the outer diameter of the shaft member <NUM> as a whole. The shaft member <NUM> is inserted and held in this circular hole.

As shown in <FIG>, the width W1 in the circumferential direction around the rotation axis X of the recess <NUM> is greater than the width W2 in the circumferential direction around the connecting portion <NUM> (W1>W2). Therefore, as shown in <FIG>, the side wall portion <NUM> of the recess <NUM> faces the side wall portion <NUM> of the connecting portion <NUM> with a gap therebetween. This gap forms an oil passage <NUM> that communicates with the inside and outside of the differential case <NUM>. The oil passage <NUM> is formed on both end sides of the connecting portion <NUM> in the circumferential direction around the rotation axis X. The circumferential width of each oil passage <NUM> around the rotation axis X is (W1 - W2)/<NUM>.

The oil passage <NUM> is located between the recess <NUM> and the connecting portion <NUM> in the circumferential direction around the rotation axis X of the differential case <NUM>. In <FIG>, the position of the oil passage <NUM> is indicated by hatching on the case member <NUM>. The oil passage <NUM> extends from the inner diameter side end of the connecting portion <NUM> to the outside in the radial direction of the rotation axis X and opens to the outer circumferential surface of the differential case <NUM>. The pinion mate gear <NUM> and the side gear 54B are accommodated on the inner diameter side of the connecting portion <NUM>. The oil OL that the pinion mate gear <NUM> and the side gear 54B have stirred flows into the inner diameter side end of the oil passage <NUM>. The oil passage <NUM> discharges the oil OL to the outside of the differential case <NUM> by centrifugal force.

As shown in <FIG>, the oil passage <NUM> has a longitudinal shape extending in the direction of the rotation axis X. At one end of the oil passage <NUM> in the direction of the rotation axis X, a groove portion <NUM> is located. As shown in <FIG>, the groove portion <NUM> is formed at the boundary between the bottom surface portion <NUM> and the side wall portion <NUM>. The groove portion <NUM> extends in the radial direction of the rotation axis X. At the other end of the oil passage <NUM> in the direction of the rotation axis X, the base <NUM> of the case member <NUM> is located.

As shown in the enlarged area of <FIG>, the outer circumferential surface 71c of the base <NUM> of the case member <NUM> is fitted into the inner circumferential surface 681a of the outer circumferential wall portion <NUM> of the plate portion <NUM> of the case member <NUM>.

The guide portion <NUM> of the case member <NUM> is disposed on the inner diameter side of the oil receiving portion <NUM> of the case member <NUM>. In this state, the leading end surface 78a of the guide portion <NUM> is located between one end surface 680a and the other end surface 680b of the oil receiving portion <NUM> in the direction of the rotation axis X. The guide portion <NUM> of the case member <NUM>, the oil receiving portion <NUM> of the case member <NUM>, and the pinion shaft <NUM> overlap in the radial direction of the rotation axis X.

<FIG> shows a diameter line Lr passing through the rotation axis X and the axis line X1. When viewed from the radial direction of the rotation axis X, the oil hole <NUM> of the case member <NUM>, the guide portion <NUM>, the recess <NUM> of the case member <NUM>, the oil groove <NUM>, the oil hole <NUM> of the pinion shaft <NUM>, and the axial internal oil passage 440B are arranged in order along the diameter line Lr. When viewed from the radial direction of the rotation axis X, the oil hole <NUM>, the guide portion <NUM>, the recess <NUM>, the oil groove <NUM>, the oil hole <NUM>, and the axial internal oil passage 440B overlap with each other. The vertex P of the recess <NUM> is located on the diameter line Lr.

As shown in <FIG>, the differential case <NUM> has the bearing B2 extrapolated to the tubular wall portion <NUM> of the case member <NUM>. The bearing B2 is in contact with the inner race on the step portion <NUM> provided on the outer circumference of the tubular wall portion <NUM> from the direction of the rotation axis X. The bearing B2 extrapolated to the tubular wall portion <NUM> is held by the support portion <NUM> of the fourth box <NUM>. The tubular wall portion <NUM> of the differential case <NUM> is rotatably supported by the fourth box <NUM> (see <FIG>) through the bearing B2.

As shown in <FIG>, the drive shaft 9B penetrating the opening 145a of the support portion <NUM> of the fourth box <NUM> is inserted from the direction of the rotation axis X and is rotatably supported by the support portion <NUM>. The tubular wall portion <NUM> functions as a shaft support portion that supports the outer circumference of the drive shaft 9B.

A lip seal RS is fixed to the inner circumference of the opening 145a. The unillustrated lip portion of the lip seal RS elastically contacts the outer circumference of the tubular wall portion <NUM> of the side gear 54B extrapolated to the drive shaft 9B.

Thereby sealing the gap between the outer circumference of the tubular wall portion <NUM> of the side gear 54B and the inner circumference of the opening 145a.

The case member <NUM> of the differential case <NUM> is supported by the plate member <NUM> via a bearing B3 extrapolated to the tubular wall portion <NUM> (see <FIG>).

Inside the case member <NUM>, a drive shaft 9A that penetrates through the through-hole 130a of the third box <NUM> is inserted from the direction of the rotation axis X.

The drive shaft 9A is provided to cross the motor shaft <NUM> of the motor <NUM> and the inner diameter side of the sun gear <NUM> of the planetary reduction gear <NUM> in the direction of the rotation axis X.

As shown in <FIG>, inside the differential case <NUM>, the side gears 54A and 54B are splined to the outer circumference of the leading end portions of the drive shafts 9A and 9B. The side gears 54A and 54B are integrally rotatably connected to the drive shafts 9A and 9B around the rotation axis X.

In this state, the side gears 54A and 54B are arranged opposite to each other with a gap in the direction of the rotation axis X. The central member <NUM> of the pinion mate shaft <NUM> is positioned between the side gears 54A and 54B.

In this embodiment, three shaft members <NUM> of the pinion mate shaft <NUM> extend radially outward from the central member <NUM>. A pinion mate gear <NUM> is supported on each of the shaft members <NUM> of the pinion mate shaft <NUM>. The side gear 54A is positioned on one side of the rotation axis X of the pinion mate gear <NUM>, and the side gear 54B is positioned on the other side. The pinion mate gears <NUM> are assembled in a state where their teeth portions are engaged with each other on the side gears 54A and 54B.

As shown in <FIG>, the inside of the fourth box <NUM> stores lubricating oil OL. The lower side of the differential case <NUM> is located within the stored oil OL.

The stored oil OL is stored up to the height at which, for example, the connecting beam <NUM> is located within the oil OL when the connecting beam <NUM> is located at the lowest position.

The stored oil OL is scraped up by the differential case <NUM> rotating around the rotation axis X during the transmission of the output rotation of the motor <NUM>.

As shown in <FIG>, an oil catch portion <NUM> is provided above the fourth box <NUM>. Part of the oil OL scraped up by the differential case <NUM> rotating around the rotation axis X flows into the oil catch portion <NUM>.

The oil catch portion <NUM> is connected to an oil passage 151a that extends on the inner diameter side of the fourth box <NUM>. As shown in <FIG>, the inner diameter end of the oil passage 151a is opened between the lip seal RS and the bearing B2.

The oil catch portion <NUM> is also connected to an oil hole 136a (see <FIG>) provided in the cylindrical connecting wall <NUM> of the third box <NUM> via an unillustrated piping.

Part of the oil OL scraped up by the differential case <NUM> rotating around the rotation axis X reaches the oil catch portion <NUM>. The oil OL is supplied to the internal space Sc of the connecting wall <NUM> through the guide portion <NUM> of the oil catch portion <NUM> and the piping <NUM>.

The third box <NUM> has a radial oil passage <NUM> that communicates with the internal space Sc.

The radial oil passage <NUM> extends radially downward from the internal space Sc. The radial oil passage <NUM> communicates with a axial oil passage <NUM> provided in the joint portion <NUM>.

A communication hole 112a is provided in the joint portion <NUM> of the first box <NUM>. The axial oil passage <NUM> communicates with an oil pooling portion <NUM> provided in the lower part of the second box <NUM> via the communication hole 112a.

The oil pooling portion <NUM> passes through the circumferential wall portion <NUM> in the direction of the rotation axis X. The oil pooling portion <NUM> communicates with the second gear chamber Sb2 provided in the fourth box <NUM>.

The operation of the power transmission device <NUM> with such a configuration will be described.

As shown in <FIG>, the power transmission device <NUM> includes a planetary reduction gear <NUM>, a differential mechanism <NUM>, and drive shafts 9A and 9B provided along the transmission path of the output rotation of the motor <NUM>.

As shown in <FIG>, when the motor <NUM> is driven, the rotor core <NUM> rotates about the rotation axis X, and the motor shaft <NUM> rotates integrally with the rotor core <NUM>. The output rotation of the motor <NUM> is input to the sun gear <NUM> of the planetary reduction gear <NUM> via the motor shaft <NUM>.

As shown in <FIG>, the sun gear <NUM> serves as the input part of the output rotation of the motor <NUM> in the planetary reduction gear <NUM>. The differential case <NUM> supporting the stepped pinion gear <NUM> serves as the output part of the input rotation.

When the sun gear <NUM> rotates about the rotation axis X with the input rotation, the stepped pinion gear <NUM> (large diameter gear portion <NUM>, small diameter gear portion <NUM>) rotates about the axis line X1 with the input rotation from the sun gear <NUM> side.

Here, the small diameter gear portion <NUM> of the stepped pinion gear <NUM> is engaged with the ring gear <NUM> fixed to the inner circumference of the fourth box <NUM>. Therefore, while the stepped pinion gear <NUM> rotates about the axis line X1, it revolves around the rotation axis X. The drive shaft 9B is located on the inner circumference of the revolving orbit of the stepped pinion gear <NUM>.

The outer diameter R2 of the small diameter gear portion <NUM> of the stepped pinion gear <NUM> is smaller than the outer diameter R1 of the large diameter gear portion <NUM> (see <FIG>).

As a result, the differential case <NUM> (case members <NUM> and <NUM>) supporting the stepped pinion gear <NUM> rotates about the rotation axis X at a lower rotational speed than the input rotation from the motor <NUM>.

Therefore, the rotation input to the sun gear <NUM> of the planetary reduction gear <NUM> is greatly reduced by the stepped pinion gear <NUM>. The reduced rotation is output to the differential case <NUM> (differential mechanism <NUM>).

Then, by rotating the differential case <NUM> with the inputted rotation about the rotation axis X, the drive shafts 9A and 9B that engage with the pinion mate gear <NUM> within the differential case <NUM> rotate around the rotation axis X. As a result, the left and right drive wheels W, W of the vehicle equipped with the power transmission device <NUM> (refer to <FIG>) rotate with the transmitted rotational driving force.

As shown in <FIG>, lubricating oil OL is stored inside the fourth box <NUM> for lubrication purposes. Therefore, the stored oil OL is scraped up by the differential case <NUM> rotating around the rotation axis X when transmitting the output rotation of the motor <NUM>.

The scraped-up oil OL lubricates the engagement portions between the sun gear <NUM> and the large diameter gear portion <NUM>, between the small diameter gear portion <NUM> and the ring gear <NUM>, and between the pinion mate gear <NUM> and the side gears 54A and 54B. Much of the oil OL scraped up by the differential case <NUM> flows into the oil catch portion <NUM>.

Some of the oil OL that flowed into the oil catch portion <NUM> flows into an oil passage 151a, one end of which is open on the upper surface of the support base <NUM>.

The inner diameter side end portion of the oil passage 151a is opened to the inner circumference of the support portion <NUM> (refer to <FIG>). Therefore, the oil OL flowing into the oil passage 151a is discharged into a clearance Rx between the inner circumference of the support portion <NUM> of the fourth box <NUM> and the tubular wall portion <NUM> of the side gear 54B.

Oil OL discharged into the clearance Rx lubricates the bearing B2 supported by the support portion <NUM>. The oil OL that lubricates the bearing B2 moves to the outer side (bearing B2 side) of the differential case <NUM> by the centrifugal force of the rotation of the differential case <NUM>.

On the outer circumference of the differential case <NUM>, a guide portion <NUM> that forms a ring shape when viewed from the direction of the rotation axis X is provided. Therefore, the oil OL that has moved to the outer diameter side is captured by a portion of the guide portion <NUM>. As shown in <FIG>, ribs <NUM> are provided on the inner circumferential side of the guide portion <NUM>. A recess is formed between the guide portion <NUM>, the ribs <NUM>, and the tubular wall portion <NUM>. This recess makes it easier for the oil OL to accumulate on the inner circumferential side of the guide portion <NUM>.

As shown in <FIG>, oil holes <NUM> are provided along the inner circumferential surface <NUM> of the guide portion <NUM> at the base <NUM> of the case member <NUM>. The oil OL is prevented from further moving to the outer diameter side by the guide portion <NUM>. The oil OL whose movement is obstructed passes through the oil hole <NUM> that opens to the inner circumference of the guide portion <NUM> to the case member <NUM> side.

The oil OL reaches the inner circumferential surface <NUM> of the guide portion <NUM> by the centrifugal force generated by the rotation of the differential case <NUM>. Many of the oil OL that have reached the inner circumferential surface <NUM> of the guide portion <NUM> flow into the oil hole <NUM> that opens in the direction of the rotation axis X without passing over the guide portion <NUM>.

As shown in <FIG>, the oil OL supplied to the oil hole <NUM> moves to the guide portion <NUM>. The long side portion 710a of the oil hole <NUM> and the inner circumferential surface 781a of the long wall portion <NUM> of the guide portion <NUM> are inclined to the radial outer side as they move away from the inner circumferential surface <NUM> of the guide portion <NUM> in the direction of the rotation axis X.

Therefore, the oil OL passing through the oil hole <NUM> and the guide portion <NUM> moves along the inclination while being subjected to centrifugal force. This promotes the movement of the oil OL towards the case member <NUM> side. In addition, due to this inclination, it is possible to reduce the re-entry of the oil OL that has moved from the guide portion <NUM> to the case member <NUM> side back to the guide portion <NUM>, and discharge it to the outside of the differential case <NUM>.

As mentioned earlier, the guide portion <NUM> is a continuous wall composed of a long wall portion <NUM>, short wall portions <NUM> and <NUM> (see <FIG>). When viewed from the direction of the rotation axis X, the guide portion <NUM> opens toward the inner diameter side. This allows the guide portion <NUM> to catch not only the oil OL flowing from the oil hole <NUM> but also the oil OL that scatters inside the differential case <NUM> (white arrow in <FIG>).

As shown in <FIG>, the oil OL that has moved from the oil hole <NUM> to the case member <NUM> side through the guide portion <NUM> is discharged from the leading end surface 78a. The inner circumferential surface 680c of the oil receiving portion <NUM> and the recess <NUM> are transversely arranged from the base <NUM> side of the case member <NUM> to the pinion gear <NUM> side along the direction of the rotation axis X at the leading end surface 78a of the guide portion <NUM>.

Therefore, the oil OL discharged from the leading end surface 78a of the guide portion <NUM> is caught by the inner circumferential surface 680c and the recess <NUM> (see <FIG>) after moving outward in the radial direction due to centrifugal force.

The inner circumferential surface 680c and the recess <NUM> are inclined in the radial direction outward as they move away from the guide portion <NUM> along the direction of the rotation axis X. The oil OL caught in the recess <NUM> moves along the inclination from one end surface 680a side to the other end surface 680b side of the oil receiving portion <NUM>. Moreover, many of the oil OL caught on the inner circumferential surface 680c gather in the recess <NUM> during the movement along the inclination.

As shown in <FIG>, when viewed from the direction of the rotation axis X, the oil OL in the recess <NUM> moves on the inclined surfaces 683a and 683b in the circumferential direction around the rotation axis X due to centrifugal force and gathers around the vertex P.

The recess <NUM> communicates with the oil groove <NUM> (clearance CL2) at the vertex P. The oil OL in the recess <NUM> is gathered at the vertex P by centrifugal force and then discharged into the oil groove <NUM>. The oil OL in the oil groove <NUM> moves radially outward by centrifugal force and flows into the oil hole <NUM> of the pinion shaft <NUM>. At this time, the washer Wc is also lubricated by the oil OL.

The oil OL flowing into the oil hole <NUM> of the pinion shaft <NUM> moves to the axial internal oil passage 440B and is finally discharged from the oil hole <NUM> (see <FIG>). At this time, the oil OL lubricates the needle bearing NB.

Furthermore, a part of the oil OL discharged into the clearance Rx passes through the oil groove <NUM> provided on the inner circumference of the tubular wall portion <NUM> of the case member <NUM>, as shown in <FIG>. The oil OL that has passed through the oil groove <NUM> is supplied to the washer <NUM> that supports the back surface of the side gear 54B to lubricate the washer <NUM>.

Furthermore, the oil OL passes through the oil groove <NUM> provided at the base <NUM> of the case member <NUM> and the oil groove <NUM> provided on the arc portion <NUM>. The oil OL that has passed through the oil groove <NUM> is supplied to the spherical washer <NUM> that supports the back surface of the pinion mate gear <NUM> to lubricate the spherical washer <NUM>.

In addition, a part of the oil OL caught by the oil catch portion <NUM> is supplied through a not-shown piping to the oil hole 136a (see <FIG>) provided on the cylindrical connecting wall <NUM> of the third box <NUM>.

The oil OL discharged into the internal space Sc from the oil hole 136a is stored in the internal space Sc. The oil OL also lubricates the bearing B4 supported by the circumferential wall portion <NUM> of the third box <NUM>.

A portion of the oil OL discharged into the internal space Sc moves to the other end 20b side of the motor shaft <NUM> through the gap between the outer circumference of the drive shaft 9A and the inner circumference of the motor shaft <NUM>.

As shown in <FIG>, the other end 20b of the motor shaft <NUM> is inserted inside the tubular wall portion <NUM> of the side gear 54A. A communication passage <NUM> communicating with the back surface of the side gear 54A is provided on the inner circumference of the tubular wall portion <NUM>.

Therefore, a portion of the oil OL discharged inside the tubular wall portion <NUM> flows through the communication passage <NUM> when it moves to the other end 20b side of the motor shaft <NUM>. The oil OL that has passed through the communication passage <NUM> is supplied to the washer <NUM> on the back surface of the side gear 54A to lubricate the washer <NUM>.

Furthermore, as shown in <FIG>, the oil OL that lubricates the washer <NUM> on the back surface of the side gear 54A moves through the oil groove <NUM> provided on the gear support portion <NUM> of the case member <NUM> and the oil groove <NUM> provided on the arc portion <NUM>. The oil OL that has passed through the oil groove <NUM> is supplied to the spherical washer <NUM> that supports the back surface of the pinion mate gear <NUM> to lubricate the spherical washer <NUM>.

As shown in <FIG>, the internal space Sc of the third box <NUM> communicates with the second gear chamber Sb2 provided in the fourth box <NUM> through the radial oil passage <NUM>, the axial oil passage <NUM>, the communication hole 112a, and the oil pooling portion <NUM> provided in the lower part of the second box <NUM>.

Therefore, the oil OL in the internal space Sc is held at the same height position as the stored oil OL in the fourth box <NUM>.

In this way, much of the oil OL swept up by the differential case <NUM> rotating around the X-axis flows into the oil catch portion15. The oil OL is supplied from the oil catch portion <NUM> to the support portion <NUM> of the fourth box <NUM> to lubricate the bearing B2. The oil OL is also supplied to the internal space Sc of the third box <NUM> to lubricate the bearing B4.

Then, the oil OL that has lubricated these bearings B2 and B4 is finally returned to the fourth box <NUM> and swept up by the rotating differential case <NUM>.

Thus, in the power transmission device <NUM>, the oil OL in the fourth box <NUM> is swept up when the drive wheels W rotate and used for lubricating bearings and gear engagement parts. The oil OL used for lubrication is returned to the fourth box <NUM> and becomes available for sweeping up again.

Furthermore, in the power transmission device <NUM>, by inserting and contacting the connecting portion <NUM> of the case member <NUM> into the recess <NUM> of the case member <NUM>, the support groove <NUM> and the support groove <NUM> face each other to form a circular hole that supports the shaft member <NUM>.

Therefore, in the embodiment, as shown in <FIG>, the shaft member <NUM> can be assembled with the case members <NUM> and <NUM> while being pre-arranged in the support groove <NUM> of the recess <NUM>.

In addition, three shaft members <NUM> can be pre-connected to the central member <NUM> and arranged in the case member <NUM>. In this case, a pinion mate shaft <NUM>, which is integrally molded with the shaft member <NUM> and the central member <NUM>, can also be used.

In addition, the circumferential width W2 of the connecting portion <NUM> around the rotation axis X is set smaller than the circumferential width W1 of the recess <NUM>. Therefore, the connecting portion <NUM> is easier to insert into the recess <NUM>.

As shown in <FIG>, when the case members <NUM> and <NUM> are assembled, a gap that serves as an oil passage <NUM> is formed between the recess <NUM> and the connecting portion <NUM>. This oil passage <NUM> improves the discharge performance of the oil OL from the inside to the outside of the differential case <NUM>. This can reduce the stirring resistance of the oil OL caused by the pinion mate gear <NUM> and the side gears 54A and 54B (see <FIG>) located on the inner diameter side of the connecting portions <NUM> and <NUM>.

In addition, as shown in <FIG>, a groove portion <NUM> is formed at the boundary between the bottom surface portion <NUM> and the side wall portion <NUM> of the case member <NUM>. This groove portion <NUM> extends along the oil passage <NUM> from the inner diameter side to the outer diameter side of the rotation axis X. The oil OL stirred by the pinion mate gear <NUM> and the side gears 54A and 54B enters the groove portion <NUM> and flows along the outer diameter side of the groove portion <NUM>. This improves the discharge performance of the oil OL from the inside to the outside of the differential case <NUM>.

One example of the power transmission device <NUM> in one aspect of the present invention is listed below:.

The shaft member <NUM> is supported by the connecting portion <NUM> in the recess <NUM>.

By configuring the power transmission device in this way, the freedom of assembly is improved.

Specifically, the shaft member <NUM> is pre-arranged in the recess <NUM> of the case member <NUM>. The connecting portion <NUM> of the case member <NUM> is inserted into the recess <NUM> and brought into contact with the shaft member <NUM>, and the case member <NUM> and the case member <NUM> are assembled. This improves the freedom of assembly compared to simply inserting the shaft member <NUM> into the hole of the differential case <NUM>.

After assembling the case members <NUM> and <NUM>, the assembly may be performed by inserting the shaft member <NUM> into the circular hole formed by the support grooves <NUM> and <NUM>. In this case, the shaft member <NUM> and the central member <NUM> of the pinion mate shaft <NUM> are molded separately. The central member <NUM> is pre-arranged in the case member <NUM> together with the pinion mate gear <NUM> and the spherical washer <NUM>, and the case member <NUM> is then assembled. Thereafter, the shaft member <NUM> is inserted into the circular hole and connected to the central member <NUM>.

(<NUM>) In the power transmission device <NUM>, the case member <NUM> preferably has a support groove <NUM> (first cutout portion) on the leading end surface <NUM> (leading end) of the connecting portion <NUM>. The shaft member <NUM> is accommodated in the support groove <NUM>.

By constructing in this way, the shaft member <NUM> is supported in the recess <NUM> while being accommodated in the support groove <NUM> of the connecting portion <NUM>. This makes it possible to stably support the shaft member <NUM>.

(<NUM>) In the power transmission device <NUM>, the case member <NUM> preferably has a support groove <NUM> (second cutout portion) for accommodating the shaft member <NUM> in the recess <NUM>.

By constructing in this way, the shaft member <NUM> is supported in the recess <NUM> while being accommodated in the support groove <NUM> of the recess <NUM>. This makes it possible to stably support the shaft member <NUM>. Furthermore, when the support groove <NUM> is provided in addition to the support groove <NUM>, the shaft member <NUM> is accommodated in the support grooves <NUM> and <NUM> from both sides in the direction of the rotation axis X, and the shaft member <NUM> can be stably supported.

Furthermore, when the connecting portion <NUM> is accommodated in the recess <NUM>, the support grooves <NUM> and <NUM> can be formed as semi-circular cutouts that are symmetrical with respect to the contact surfaces (leading end surface <NUM> and bottom surface portion <NUM>).

This allows the support grooves <NUM> and <NUM> to form circular holes that match the outer diameter of the shaft member <NUM>. By accommodating the shaft member <NUM> in these circular holes, the shaft member <NUM> can be stably supported.

(<NUM>) The power transmission device <NUM> has an oil passage <NUM> between the recess <NUM> and the connecting portion <NUM> in the circumferential direction (circumferential direction) around the rotation axis X of the differential case <NUM>.

The oil passage <NUM> opens on the outer circumferential surface of the differential case <NUM>.

By configuring the power transmission device in this way, it becomes easier to discharge oil OL from the inside to the outside of the differential case <NUM> via the oil passage <NUM>, thereby reducing the agitation resistance of the oil OL of the pinion mate gear <NUM> arranged inside the differential case <NUM>.

In addition, in the embodiment, the width W1 in the circumferential direction around the rotation axis X of the recess <NUM> is set larger than the width W2 in the circumferential direction around the connecting portion <NUM>. As a result, when the connecting portion <NUM> is inserted into the recess <NUM>, the side wall portion <NUM> of the recess <NUM> faces the side wall portion <NUM> of the connecting portion <NUM> with a gap in between. In the embodiment, this gap is used as the oil passage <NUM>. This eliminates the need to separately form the oil passage <NUM>, thereby reducing manufacturing costs.

Note that the oil passage <NUM> is not limited to the gap between the side wall portion <NUM> and the side wall portion <NUM>, and may be separately formed.

(<NUM>) The oil passage <NUM> preferably has an elongated shape extending in the longitudinal direction of the rotation axis X.

The oil passage <NUM> located between the recess <NUM> and the connecting portion <NUM> has a longitudinal shape that extends in the direction of the rotation axis X, which allows for clearance between the recess <NUM> and the connecting portion <NUM>. This makes it easier to insert the connecting portion <NUM> into the recess <NUM> and to assemble the case members <NUM> and <NUM>.

(<NUM>) The power transmission device <NUM> preferably has multiple shaft members <NUM>.

Depending on the configuration of the embodiment, even when assembling multiple shaft members <NUM>, it is possible to assemble the case members <NUM> and <NUM> with the shaft members <NUM> already arranged in the case member <NUM>. This improves the freedom of assembly. Note that in the embodiment, an example was described in which the pinion mate shaft <NUM> has three shaft members <NUM>, but the shaft members <NUM> may be two or four or more.

(<NUM>) The power transmission device <NUM> preferably has three or more shaft members <NUM>.

Depending on the configuration of the embodiment, even when having three or more shaft members <NUM>, it is possible to arrange the shaft members <NUM> in the case member <NUM> in advance and perform the assembly. This improves the freedom of assembly.

(<NUM>) The power transmission device <NUM> preferably has a pinion mate shaft <NUM> comprising multiple shaft members <NUM> and a central member <NUM> that supports the multiple shafts.

Depending on the configuration of the embodiment, it is possible to arrange the shaft members <NUM> and the central member <NUM> in the case member <NUM> in advance by connecting them, and perform the assembly. This improves the freedom of assembly. Note that the state of pre-connecting the shaft members <NUM> and the central member <NUM> includes a case where the shaft members <NUM> and the central member <NUM> are integrally molded.

(<NUM>) In the power transmission device <NUM>, it is preferable that the central member <NUM> and the plurality of shaft members <NUM> are integrally molded.

By using the pinion mate shaft <NUM> in which the shaft member <NUM> and the central member <NUM> are integrally molded, the assembly efficiency can be improved.

(<NUM>) In the power transmission device <NUM>, the case member <NUM> preferably has a base <NUM> (plate). The base <NUM> is connected to the connecting portion <NUM> and fitted to the case member <NUM>.

Specifically, the case member <NUM> has a plate portion <NUM> that connects to the recess <NUM> of the connecting portion <NUM>. The base <NUM> is provided on the side away from the case member <NUM> of the connecting portion <NUM>. The plate portion <NUM> is provided on the side of the case member <NUM> of the recess <NUM>. When assembling the case members <NUM> and <NUM>, the connecting portion <NUM> is inserted into the recess <NUM> and the base <NUM> is fitted to the plate portion <NUM>. This makes it possible to assemble with clearance without the need to fit the connecting portion <NUM> into the recess <NUM>, improving the assembly performance.

(<NUM>) In the power transmission device <NUM>, the case member <NUM> preferably has a step portion <NUM> provided on the outer circumferential surface at the boundary between the base <NUM> and the connecting portion <NUM>. The radius R4 of the outer circumferential surface 71c on the base <NUM> side at the step portion <NUM> is smaller than the radius R3 of the outer circumferential surface 74a on the connecting portion <NUM> side.

By configuring in this way, the connecting portion <NUM> side of the case member <NUM> that supports the shaft member <NUM> is made thick to increase its rigidity, while the base <NUM> side, where rigidity is not required, is made thin, enabling the differential case <NUM> to be lightweight.

(<NUM>) In the power transmission device <NUM>, the case member <NUM> preferably has.

The case member <NUM> has a step portion 63a on the outer circumferential surface at the boundary between the first portion 6A and the second portion 6B.

By configuring in this way, it is possible to change the thickness of the first portion 6A and the second portion 6B of the case member <NUM> in the radial direction of the rotation axis X, enabling lightweighting of the differential case <NUM>.

<FIG> is a parts diagram illustrating the assembly of case members <NUM> and <NUM> in deformation example <NUM>.

<FIG> shows the state before assembly, and <FIG> shows the state after assembly.

As shown in <FIG>, in deformation example <NUM>, the case member <NUM> has a recess 640A that recesses in the direction of the rotation axis X. The case member <NUM> has a connecting portion 74A which is a protrusion in the direction of the rotation axis X. However, in deformation example <NUM>, a support groove for supporting the shaft member <NUM> is not formed in the recess 640A and the connecting portion 74A.

The recess 640A of the case member <NUM> has a bottom surface portion 643A and side wall portions 644A which connect to both ends in the circumferential direction around the rotation axis X of the bottom surface portion 643A.

In deformation example <NUM>, the bottom surface portion 643A is formed in a cross-sectional arc shape along the outer diameter of the shaft member <NUM>.

The connecting portion 74A of the case member <NUM> has a leading end surface 743A and side wall portions 744A. The side wall portions 744A are connected to both ends in the circumferential direction around the rotation axis X of the leading end surface 743A.

The width W10 of the circumferential direction of the recess 640A is set larger than the width W20 of the circumferential direction of the connecting portion 74A. That is, the connecting portion 74A can be inserted into the recess 640A. Here, the width W10 means the length from one side wall portion 644A connected to the bottom surface portion 643A to the other side wall portion 644A. The width W20 means the length from one side wall portion 744A connected to the leading end surface 743A to the other side wall portion 744A.

The length L20 of the connecting portion 74A in the direction of the rotation axis X matches the length L10 shown in the case member <NUM>. The length L10 means the length from the tangent line Im10 passing through the outer peripheral edge closest to the case member <NUM> of the shaft member <NUM> to the end on the case member <NUM> side of the side wall portion 644A.

As shown in <FIG>, the assembly of the case members <NUM> and <NUM> can be performed by placing the shaft member <NUM> in advance in the recess 640A of the case member <NUM>.

The shaft member <NUM> is placed in contact with the bottom surface portion 643A. When the connecting portion 74A is inserted into the recess 640A, the leading end surface 743A of the connecting portion 74A comes into contact with the outer peripheral edge of the shaft member <NUM>. The shaft member <NUM> is supported in the recess 640A in a state of being sandwiched between the bottom surface portion 643A and the leading end surface 743A (refer to <FIG>).

In this way, in the deformation example <NUM>, the power transmission device <NUM> has a connecting portion 74A (protrusion) that protrudes in the direction of the rotation axis X and is provided in the case member <NUM>, and a recess 640A that is provided in the case member <NUM> and sinks in the direction of the rotation axis X. The shaft member <NUM> is supported by the connecting portion 74A in the recess 640A.

This configuration improves the degree of freedom in assembly, as in the embodiment.

In the embodiments of the present invention, an example of applying the power transmission device to a vehicle is illustrated. However, the present invention is not limited to this embodiment. The power transmission device can also be applied to something other than a vehicle.

Claim 1:
A power transmission device (<NUM>),
comprising:
- a case (<NUM>) comprising a first case member (<NUM>) and a second case member (<NUM>) which is assembled with the first case member (<NUM>), and
- a shaft member (<NUM>) supported by the case (<NUM>),
characterized in that:
- the first case member (<NUM>) has a protrusion (<NUM>) protruding in the axial direction (X) along the assembly direction of the case (<NUM>),
- the second case member (<NUM>) has a recess (<NUM>) recessed in the axial direction (X),
- the shaft member (<NUM>) is supported by the protrusion (<NUM>) in the recess (<NUM>), and
- an oil passage (<NUM>) is formed between the recess (<NUM>) and the protrusion (<NUM>) in a circumferential direction of the case (<NUM>).