Patent Description:
Disclosed in <CIT> is a power transmission device for an electric automobile that has a bevel gear type differential mechanism and a planetary gear mechanism. The planetary gear mechanism of Patent Document <NUM> comprises a stepped pinion gear having a large pinion gear and a small pinion gear. <CIT> and <CIT> each disclose a power transmission device according to the preamble of claim <NUM>.

In the power transmission device, the constituent components of the power transmission device are arranged closely. To suitably lubricate each of the closely arranged constituent components, various contrivances are necessary, and there is a desire to have a structure with a high degree of freedom in lubrication design in power transmission devices.

A power transmission device according to the invention is defined in claim <NUM>.

According to certain modes of the present invention, it is possible to provide a power transmission device having a structure with a high degree of freedom for lubrication design.

Following, an embodiment of the present invention is explained.

<FIG> is a skeleton diagram for explaining a power transmission device <NUM> according to the present embodiment.

<FIG> is a cross section schematic diagram for explaining the power transmission device <NUM> of the present embodiment.

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

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

As shown in <FIG>, the power transmission device <NUM> has a motor <NUM>, and the planetary reduction gear <NUM> (reduction mechanism) that reduces the output rotation of the motor <NUM> and inputs it to the differential mechanism <NUM>. The power transmission device <NUM> also has drive shafts <NUM> (9A, 9B) as the drive shaft, and a park lock mechanism <NUM>.

In the power transmission device <NUM>, the park lock mechanism <NUM>, the planetary reduction gear <NUM>, the differential mechanism <NUM>, and the drive shafts <NUM> (9A, 9B) are provided along the transmission route of the output rotation around the rotation axis X of the motor <NUM>. The axis line of the drive shafts <NUM> (9A, 9B) is coaxial with the rotation axis X of the motor <NUM>.

In the power transmission device <NUM>, after being reduced by the planetary reduction gear <NUM> and inputted to the differential mechanism <NUM>, the output rotation of the motor <NUM> is transmitted via the drive shafts <NUM> (9A, 9B) to left and right drive wheels W, W of a vehicle in which the power transmission device <NUM> is mounted.

Here, 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>, and the drive shafts <NUM> (9A, 9B) are connected downstream of the differential mechanism <NUM>.

As shown in <FIG>, a body box <NUM> of the power transmission <NUM> has a first box <NUM> that houses the motor <NUM>, and a second box <NUM> that is externally fitted on the first box <NUM>. The body box <NUM> also has a third box <NUM> assembled on the first box <NUM>, and a fourth box <NUM> (box) assembled on the second box <NUM>.

The first box <NUM> has a cylindrical support wall part <NUM>, and a flange shaped junction part <NUM> provided on one end 111a of the support wall part <NUM>.

In the first box <NUM>, the support wall part <NUM> is provided facing along the rotation axis X of the motor <NUM>. The motor <NUM> is housed inside the support wall part <NUM>.

The junction part <NUM> is provided facing orthogonal to the rotation axis X. The junction part <NUM> is formed with a larger outer diameter than the support wall part <NUM>.

The second box <NUM> has a cylindrical peripheral wall part <NUM>, a flange shaped junction part <NUM> provided on one end 121a of the peripheral wall part <NUM>, and a flange shaped junction part <NUM> provided on another end 121b of the peripheral wall part <NUM>.

The peripheral wall part <NUM> is formed with an inner diameter that can be externally fitted on the support wall part <NUM> of the first box <NUM>.

The first box <NUM> and the second box <NUM> are assembled to each other by the peripheral wall part <NUM> of the second box <NUM> being externally fitted on the support wall part <NUM> of the first box <NUM>.

The junction part <NUM> of the one end 121a side of the peripheral wall part <NUM> abuts the junction part <NUM> of the first box <NUM> from the rotation axis X direction. These junction parts <NUM>, <NUM> are linked to each other by bolts (not illustrated).

In the first box <NUM>, a plurality of recessed grooves 111b are provided on the outer circumference of the support wall part <NUM>. The plurality of recessed grooves 111b are provided with a gap open in the rotation axis X direction. Each of the recessed grooves 111b is provided along the entire circumference in the circumferential direction around the rotation axis X.

The peripheral wall part <NUM> of the second box <NUM> is externally fitted on the support wall part <NUM> of the first box <NUM>. The openings of the recessed grooves 111b are closed by the peripheral wall part <NUM>. A plurality of cooling paths CP through which cooling water is circulated are formed between the support wall part <NUM> and the peripheral wall part <NUM>.

At the outer circumference of the support wall part <NUM> of the first box <NUM>, ring grooves 111c, 111c are formed at both sides of the region in which the recessed grooves 111b are provided. Seal rings <NUM>, <NUM> are externally engaged and attached to the ring grooves 111c, 111c.

These seal rings <NUM> are press fitted on the inner circumference of the peripheral wall part <NUM> that is externally fitted on the support wall part <NUM>, and seal the gap between the outer circumference of the support wall part <NUM> and the inner circumference of the peripheral wall part <NUM>.

On the other end 121b of the second box <NUM>, a wall part <NUM> extending to the inner diameter side is provided. The wall part <NUM> is provided facing orthogonal to the rotation axis X. An opening 120a in which the drive shaft 9A is inserted is opened in the region intersecting the rotation axis X of the wall part <NUM>.

In the wall part <NUM>, a cylindrical motor support unit <NUM> that surrounds the opening 120a is provided on the motor <NUM> side (right side in the drawing) surface.

The motor support unit <NUM> is inserted inside a coil end 253b described later. The motor support unit <NUM> faces an end part 21b of a rotor core <NUM> with a gap open in the rotation axis X direction.

In the peripheral wall part <NUM> of the second box <NUM>, in the lower region in the vertical line direction with the mounted state of the power transmission device <NUM> in the vehicle as reference, the thickness in the radial direction is thicker than the upper region.

In this region that is thick in the radial direction, an oil reservoir <NUM> is provided penetrating in the rotation axis X direction.

The oil reservoir <NUM> is connected via a communication hole 112a to an axial oil passage <NUM> provided in a junction part <NUM> of the third box <NUM>. The communication hole 112a is provided in the junction part <NUM> of the first box <NUM>.

The third box <NUM> has a wall part <NUM> that is orthogonal to the rotation axis X. A junction part <NUM> that forms a ring shape seen from the rotation axis X direction is provided on the outer circumference part of the wall part <NUM>.

Seen from the first box <NUM>, the third box <NUM> is positioned on the opposite side (right side in the drawing) from the differential mechanism <NUM>. The junction part <NUM> of the third box <NUM> is joined to the junction part <NUM> of the first box <NUM> from the rotation axis X direction. The third box <NUM> and the first box <NUM> are linked to each other by bolts (not illustrated). In this state, in the first box <NUM>, the opening on the junction part <NUM> side (right side in the drawing) of the support wall part <NUM> is blocked by the third box <NUM>.

In the third box <NUM>, an insertion hole 130a of the drive shaft 9A is provided in the center of the wall part <NUM>.

A lip seal RS is provided on the inner circumference of the insertion hole 130a. In the lip seal RS, a lip section (not illustrated) is in elastic contact with the outer circumference of the drive shaft 9A. The gap between the inner circumference of the insertion hole 130a and the outer circumference of the drive shaft 9A is sealed by the lip seal RS.

A peripheral wall part <NUM> that surrounds the insertion hole 130a is provided on the surface of the first box <NUM> side (left side in the drawing) in the wall part <NUM>. The drive shaft 9A is supported with a bearing B4 interposed on the inner circumference of the peripheral wall part <NUM>.

Seen from the peripheral wall part <NUM>, a motor support unit <NUM> is provided on the motor <NUM> side (left side in the drawing). The motor support unit <NUM> forms a tube shape that surrounds the rotation axis X with a gap open.

A cylindrical connecting wall <NUM> is connected to the outer circumference of the motor support unit <NUM>. The connecting wall <NUM> is formed with a larger outer diameter than the peripheral wall part <NUM> of the wall part <NUM> side (right side in the drawing). The connecting wall <NUM> is provided facing along the rotation axis X, and extends in the direction separating from the motor <NUM>. The connecting wall <NUM> connects the motor support unit <NUM> and the wall part <NUM> of the third box <NUM>.

The motor support unit <NUM> is supported by the third box <NUM> with the connecting wall <NUM> interposed. One end 20a side of a motor shaft <NUM> penetrates the inside of the motor support unit <NUM> from the motor <NUM> side to the peripheral wall part <NUM> side.

A bearing B1 is supported on the inner circumference of the motor support unit <NUM>. The outer circumference of the motor shaft <NUM> is supported by the motor support unit <NUM> with the bearing B1 interposed.

The lip seal RS is provided on the position adjacent to the bearing B1.

In the third box <NUM>, an oil hole 136a described later is open at the inner circumference of the connecting wall <NUM>. Oil OL from the oil hole 136a is made to flow into a space (internal space Sc) surrounded by the connecting wall <NUM>. The lip seal RS is provided to prevent the inflow of oil OL inside the connecting wall <NUM> to the motor <NUM> side.

The fourth box <NUM> has a peripheral wall part <NUM> that surrounds the outer circumference of the planetary reduction gear <NUM> and the differential mechanism <NUM>, and a flange shaped junction part <NUM> provided on the end part of the second box <NUM> side in the peripheral wall part <NUM>.

The fourth box <NUM> is positioned at the differential mechanism <NUM> side (left side in the drawing) seen from the second box <NUM>. The junction part <NUM> of the fourth box <NUM> is joined from the rotation axis X direction to the junction part <NUM> of the second box <NUM>. The fourth box <NUM> and the second box <NUM> are linked to each other by bolts (not illustrated).

Inside the body box <NUM> of the power transmission device <NUM>, a motor chamber Sa that houses the motor <NUM> and a gear chamber Sb that houses the planetary reduction gear <NUM> and the differential mechanism <NUM> are formed.

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

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

A plate member <NUM> is provided on the inside of the gear chamber Sb.

The plate member <NUM> is fixed to the fourth box <NUM>.

In the plate member <NUM>, the gear chamber Sb is partitioned into a first gear chamber Sb1 that houses the planetary reduction gear <NUM> and the differential mechanism <NUM>, and a second gear chamber Sb2 that houses the park lock mechanism <NUM>.

The second gear chamber Sb2 is positioned between the first gear chamber Sb1 and the motor chamber Sa in the rotation axis X direction.

The motor <NUM> has the cylindrical motor shaft <NUM>, the cylindrical rotor core <NUM> externally fitted on the motor shaft <NUM>, and a stator core <NUM> that surrounds the outer circumference of the rotor core <NUM> with a gap open.

In the motor shaft <NUM>, bearings B1, B1 are externally fitted and fixed at both sides of the rotor core <NUM>.

The bearing B1 positioned at one end 20a side (right side in the drawing) of the motor shaft <NUM> seen from the rotor core <NUM> is supported on the inner circumference of the motor support unit <NUM> of the third box <NUM>. The bearing B1 positioned at the other end 20b side is supported on the inner circumference of the cylindrical motor support unit <NUM> of the second box <NUM>.

The motor support units <NUM>, <NUM> are arranged facing with a gap open in the rotation axis X direction on the one end part 21a and the other end part 21b of the rotor core <NUM> on the inner diameter side of coil ends 253a, 253b described later.

The rotor core <NUM> is formed by laminating a plurality of silicon steel sheets, and each of the silicon steel sheets is externally fitted on the motor shaft <NUM> in a state where relative rotation with the motor shaft <NUM> is regulated.

Seen from the rotation axis X direction of the motor shaft <NUM>, the silicon steel sheet has a ring shape. At the outer circumference side of the silicon steel sheet, N pole and S pole magnets (not illustrated) are provided alternately in the circumferential direction around the rotation axis X.

The stator core <NUM> surrounding the outer circumference of the rotor core <NUM> is formed by laminating a plurality of electromagnetic steel sheets. The stator core <NUM> is fixed to the inner circumference of the cylindrical support wall part <NUM> of the first box <NUM>.

Each of the electromagnetic steel sheets has a ring-shaped yoke part <NUM> fixed to the inner circumference of the support wall part <NUM>, and a teeth part <NUM> projecting to the rotor core <NUM> side from the inner circumference of the yoke part <NUM>.

With the present embodiment, the stator core <NUM> having a configuration in which a winding <NUM> is distributed and wound across a plurality of teeth parts <NUM> is adopted. The stator core <NUM> has a longer length in the rotation axis X direction than the rotor core <NUM> by the amount of the coil ends 253a, 253b projecting in the rotation axis X direction.

It is also possible to adopt the stator core of a configuration in which the windings are concentrically wound on each of the plurality of teeth parts <NUM> projecting to the rotor core <NUM> side.

The opening 120a is provided in the wall part <NUM> (motor support unit <NUM>) of the second box <NUM>. The other end 20b side of the motor shaft <NUM> is positioned inside the fourth box <NUM>, penetrating the opening 120a at the differential mechanism <NUM> side (left side in the drawing).

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

As shown in <FIG>, in the motor shaft <NUM>, a step <NUM> is provided in a region positioned inside the fourth box <NUM>. The step <NUM> is positioned in the vicinity of the motor support unit <NUM>. The lip seal RS supported on the inner circumference of the motor support unit <NUM> is abutting the outer circumference of the region between the step <NUM> and the bearing B1.

The lip seal RS is partitioned into the motor chamber Sa that houses the motor <NUM> and the gear chamber Sb inside the fourth box <NUM>.

The oil OL for lubricating the planetary reduction gear <NUM> and the differential mechanism <NUM> is sealed at the inner diameter side of the fourth box <NUM> (see <FIG>).

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

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

The parking gear <NUM> and a sun gear <NUM> are spline fitted on the outer circumference of the fitted part <NUM>.

In the parking gear <NUM>, one side surface of the parking gear <NUM> in the rotation axis X direction abuts the step <NUM> (right side in the drawing). One end 410a of a cylindrical base <NUM> of the sun gear <NUM> abuts the other side surface of the parking gear <NUM> (left side in the drawing).

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

The sun gear <NUM> and the parking gear <NUM> are provided in a state sandwiched between the nut N and the step <NUM>, without being able to rotate relatively to the motor shaft <NUM>.

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

The stepped pinion gear <NUM> (pinion gear) has the large diameter gear part <NUM> that engages with the sun gear <NUM>, and a small diameter gear part <NUM> with a smaller diameter than the large diameter gear part <NUM>.

The stepped pinion gear <NUM> is a gear component in which the large diameter gear part <NUM> and the small diameter gear part <NUM> are provided integrally aligned in an axis line X1 direction parallel to the rotation axis X.

The large diameter gear part <NUM> is formed with an outer diameter R1 greater than an outer diameter R2 of the small diameter gear part <NUM>.

The stepped pinion gear <NUM> is provided facing along the axis line X1. In this state, the large diameter gear part <NUM> is positioned at the motor <NUM> side (right side in the drawing).

The outer circumference of the small diameter gear part <NUM> is engaged with the inner circumference of a ring gear <NUM>. The ring gear <NUM> forms a ring shape that surrounds the rotation axis X with a gap open. A plurality of engagement teeth <NUM> projecting radially outward are provided on the outer circumference of the ring gear <NUM>. The plurality of engagement teeth <NUM> have a plurality provided at prescribed intervals in the circumferential direction around the rotation axis X.

In the ring gear <NUM>, the engagement teeth <NUM> provided on the outer circumference are spline fitted to teeth 146a provided on a support wall part <NUM> of the fourth box <NUM>. In the ring gear <NUM>, rotation around the rotation axis X is regulated by engaging with the support wall part <NUM> as a ring gear support part.

The stepped pinion gear <NUM> has a through hole <NUM> penetrating the inner diameter side of the large diameter gear part <NUM> and the small diameter gear part <NUM> in the axis line X1 direction.

The stepped pinion gear <NUM> is supported to be able to rotate on the outer circumference of a pinion shaft <NUM> penetrating the through hole <NUM> with the needle bearings NB, NB interposed.

On the outer circumference of the pinion shaft <NUM>, a middle spacer MS is interposed between the needle bearing NB that supports the inner circumference of the large diameter gear part <NUM> and the needle bearing NB that supports the inner circumference of the small diameter gear part <NUM>.

As shown in <FIG>, a shaft-internal oil passage <NUM> is provided on the inside of the pinion shaft <NUM>. The shaft-internal oil passage <NUM> penetrates from one end 44a of the pinion shaft <NUM> to another end 44b along the axis line X1.

Oil holes <NUM>, <NUM> that communicate between the shaft-internal oil passage <NUM> and the outer circumference of the pinion shaft <NUM> are provided on the pinion shaft <NUM>.

The oil hole <NUM> opens in the region in which the needle bearing NB that supports the inner circumference of the large diameter gear part <NUM> is provided.

The oil hole <NUM> opens in the region in which the needle bearing NB that supports the inner circumference of the small diameter gear part <NUM> is provided.

In the pinion shaft <NUM>, the oil holes <NUM>, <NUM> open inside the region in which the stepped pinion gear <NUM> is externally fitted.

Furthermore, an introduction path <NUM> for introducing the oil OL into the shaft-internal oil passage <NUM> is provided in the pinion shaft <NUM>.

In the outer circumference of the pinion shaft <NUM>, the introduction path <NUM> opens in the region positioned inside a support hole 71a of a second case unit <NUM> described later. The introduction path <NUM> communicates between the shaft-internal oil passage <NUM> and the outer circumference of the pinion shaft <NUM>.

A case-internal oil passage <NUM> is opened on the inner circumference of the support hole 71a. The case-internal oil passage <NUM> communicates between the inner circumference of a guide unit <NUM> projecting from a base <NUM> of the second case unit <NUM> and the inner circumference of the support hole 71a.

In the cross section view along the axis line X1, the case-internal oil passage <NUM> is inclined with respect to the axis line X1. The case-internal oil passage <NUM> is inclined facing toward a slit <NUM> provided in the base <NUM> as it faces the rotation axis X side.

The oil OL scooped up by a differential case <NUM> described later flows into the case-internal oil passage <NUM>. The oil OL that moves to the outer diameter side by centrifugal force due to rotation of the differential case <NUM> also flows into the case-internal oil passage <NUM>.

The oil OL that flows into the introduction path <NUM> from the case-internal oil passage <NUM> flows into the shaft-internal oil passage <NUM> of the pinion shaft <NUM>. The oil OL that flows into the shaft-internal oil passage <NUM> is discharged radially outward from the oil holes <NUM>, <NUM>. The oil OL discharged from the oil holes <NUM>, <NUM> lubricates the needle bearing NB externally fitted on the pinion shaft <NUM>.

In the pinion shaft <NUM>, a through hole <NUM> is provided more to the other end 44b side than the region in which the introduction path <NUM> is provided. The through hole <NUM> penetrates the pinion shaft <NUM> in the diameter line direction.

The pinion shaft <NUM> is provided so that the through hole <NUM> and an insertion hole <NUM> of the second case unit <NUM> described later are in phase around the axis line X1. A positioning pin P inserted in the insertion hole <NUM> penetrates the through hole <NUM> of the pinion shaft <NUM>. As a result, the pinion shaft <NUM> is supported on the second case unit <NUM> side in a state with rotation around the axis line X1 regulated.

As shown in <FIG>, on the one end 44a side in the lengthwise direction of the pinion shaft <NUM>, a region projecting from the stepped pinion gear <NUM> is a first shaft part <NUM>. The first shaft part <NUM> is supported by a support hole 61a provided in a first case unit <NUM> of the differential case <NUM>.

At the other end 44b side in the lengthwise direction of the pinion shaft <NUM>, the region projecting from the stepped pinion gear <NUM> is a second shaft part <NUM>. The second shaft part <NUM> is supported by the support hole 71a provided in the second case unit <NUM> of the differential case <NUM>.

Here, the first shaft part <NUM> means a region of the one end 44a side in which the stepped pinion gear <NUM> is not externally fitted in the pinion shaft <NUM>. The second shaft part <NUM> means a region of the other end 44b side in which the stepped pinion gear <NUM> is not externally fitted in the pinion shaft <NUM>.

In the pinion shaft <NUM>, the length of the axis line X1 direction is longer for the second shaft part <NUM> than the first shaft part <NUM>.

Following, the main configuration of the differential mechanism <NUM> is explained.

<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>.

As shown in <FIG>, the differential case <NUM> as a case houses the differential mechanism <NUM>. The differential case <NUM> is formed by assembling the first case unit <NUM> and the second case unit <NUM> in the rotation axis X direction. In the present embodiment, the first case unit <NUM> and the second case unit <NUM> of the differential case <NUM> have a function as carriers that support the pinion shaft <NUM> of the planetary reduction gear <NUM>.

As shown in <FIG>, three pinion mate gears <NUM> and three pinion mate shafts <NUM> are provided between the first case unit <NUM> and the second case unit <NUM> of the differential case <NUM>. The pinion mate shafts <NUM> function as support shafts that support the pinion mate gears <NUM>.

The pinion mate shafts <NUM> are provided at equal intervals in the circumferential direction around the rotation axis X (see <FIG>).

The end part of the inner diameter side of each pinion mate shaft <NUM> is linked to a common linking part <NUM>.

One pinion mate gear <NUM> each is externally fitted on the pinion mate shafts <NUM>. Each pinion mate gear <NUM> is in contact with the linking part <NUM> from the radial outward side of the rotation axis X.

Each of the pinion mate gears <NUM> in this state is supported to be rotatable on the pinion mate shaft <NUM>.

As shown in <FIG>, a spherical washer <NUM> is externally fitted on the pinion mate shaft <NUM>. The spherical washer <NUM> is in contact with the spherical outer circumference of the pinion mate gear <NUM>.

In the differential case <NUM>, the side gear 54A is positioned at one side of the linking part <NUM> in the rotation axis X direction, and a side gear 54B is positioned at the other side. The side gear 54A is supported to be rotatable on the first case unit <NUM>. The side gear 54B is supported to be rotatable on the second case unit <NUM>.

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

From <FIG> are drawings for explaining the first case unit <NUM>.

<FIG> is a perspective view of the first case unit <NUM> seen from the second case unit <NUM> side.

<FIG> is a plan view of the first case unit <NUM> seen from the second case unit <NUM> side.

<FIG> is a schematic diagram of the A-A cross section in <FIG>. <FIG> shows the arrangement of the pinion mate shaft <NUM> and the pinion mate gear <NUM> using virtual lines.

<FIG> is a schematic diagram of the A-A cross section in <FIG>. <FIG> shows the arrangement of the side gear 54A, the stepped pinion gear <NUM>, and the drive shaft 9A using virtual lines while omitting an illustration of a linking beam <NUM> of the paper surface back side.

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

As shown in <FIG> and <FIG>, an opening <NUM> is provided in the center of the base <NUM>. A cylinder wall part <NUM> that surrounds the opening <NUM> is provided on the surface on the side opposite to the second case unit <NUM> (right side in the drawing) in the base <NUM>. The outer circumference of the cylinder wall part <NUM> is supported by the plate member <NUM> with a bearing B3 interposed (see <FIG>).

Three linking beams <NUM> extending to the second case unit <NUM> side are provided on the surface of the second case unit <NUM> side (left side in the drawing) in the base <NUM>.

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

The linking beams <NUM> have a base <NUM> orthogonal to the base <NUM> and a linking part <NUM> that is wider than the base <NUM>.

As shown in <FIG>, a tip surface 64a of the linking part <NUM> is a flat surface orthogonal to the rotation axis X. A support groove <NUM> for supporting the pinion mate shaft <NUM> is provided on the tip surface 64a.

As shown in <FIG>, the support groove <NUM> seen from the rotation axis X direction is formed in a straight line along a radius line L of the ring-shaped base <NUM>. The support groove <NUM> crosses the center of the linking part <NUM> from the inner diameter side to the outer diameter side in the circumferential direction around the rotation axis X.

As shown in <FIG> and <FIG>, the support groove <NUM> forms a semicircle shape along the outer diameter of the pinion mate shaft <NUM>. The support groove <NUM> is formed at a depth that can house half of the cylindrical pinion mate shaft <NUM>. Specifically, the support groove <NUM> is formed at a depth corresponding to half the diameter Da of the pinion mate shaft <NUM> (= Da/<NUM>).

An arc part <NUM> is formed in a shape along the outer circumference of the pinion mate gear <NUM> on the inner diameter side (rotation axis X side) of the linking part <NUM>.

In the arc part <NUM>, the outer circumference of the pinion mate gear <NUM> is supported with the spherical washer <NUM> interposed.

In the arc part <NUM>, an oil groove <NUM> is provided facing along the radius line L noted above. The oil groove <NUM> is provided in a range from the support groove <NUM> of the pinion mate shaft <NUM> to a gear support part <NUM> fixed to the inner circumference of the linking part <NUM>.

The gear support part <NUM> is connected to the boundary of the base <NUM> and the linking part <NUM>. The gear support part <NUM> is provided facing orthogonal to the rotation axis X. The gear support part <NUM> has a through hole <NUM> at the center.

As shown in <FIG>, the outer circumference of the gear support part <NUM> is connected to the inner circumference of the three linking parts <NUM>. In this state, the center of the through hole <NUM> is positioned on the rotation axis X.

As shown in <FIG> and <FIG>, in the gear support part <NUM>, a recess <NUM> surrounding the through hole <NUM> is provided on the surface of the side opposite to the base <NUM> (left side in the drawing). In the recess <NUM>, a ring-shaped washer <NUM> that supports the back surface of the side gear 54A is housed.

A cylindrical cylinder wall part <NUM> is provided on the back surface of the side gear 54A. The washer <NUM> is externally fitted on the cylinder wall part <NUM>.

Seen from the rotation axis X direction, three oil grooves <NUM> are provided on the surface of the recess <NUM> side in the gear support part <NUM>. The oil grooves <NUM> are provided at prescribed intervals in the circumferential direction around the rotation axis X.

The oil groove <NUM> extends from the inner circumference of the gear support part <NUM> to the outer circumference along the radius line L noted above. The oil groove <NUM> is in contact with the oil groove <NUM> on the arc part <NUM> side noted above.

As shown in <FIG> and <FIG>, the support holes 61a of the pinion shaft <NUM> are open on the base <NUM>. The support holes 61a are open at the region between the linking beams <NUM>, <NUM> arranged at prescribed intervals in the circumferential direction around the rotation axis X.

A boss part <NUM> surrounding the support hole 61a is provided on the base <NUM>. A washer Wc (see <FIG>) externally fitted on the pinion shaft <NUM> is in contact with the boss part <NUM> from the rotation axis X direction.

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

As shown in <FIG>, the oil groove <NUM> is formed in a tapered shape in which the circumferential direction width around the rotation axis X becomes narrower as it approaches the boss part <NUM>. The oil groove <NUM> is connected to an oil groove <NUM> provided on the boss part <NUM>.

In the linking part <NUM>, bolt holes <NUM>, <NUM> are provided at both sides of the support groove <NUM>.

A linking part <NUM> of the second case unit <NUM> side is joined from the rotation axis X direction to the linking part <NUM> of the first case unit <NUM>. The first case unit <NUM> and the second case unit <NUM> are joined to each other by the bolts B that penetrate the linking part <NUM> of the second case unit <NUM> side being screwed into bolt holes <NUM>, <NUM>.

<FIG> are drawings for explaining the second case unit <NUM>.

<FIG> is a perspective view of the second case unit <NUM> seen from the first case unit <NUM> side.

<FIG> is a plan view of the second case unit <NUM> seen from the first case unit <NUM> side.

<FIG> is a schematic diagram of the A-A cross section in <FIG>. <FIG> shows the arrangement of the side gear 54B, the stepped pinion gear <NUM>, and the drive shaft 9B using virtual lines while omitting an illustration of the linking part <NUM> at the paper surface back side.

<FIG> is a perspective view of the second case unit <NUM> seen from the side opposite to the first case unit <NUM>.

<FIG> is a plan view of the second case unit <NUM> seen from the side opposite to the first case unit <NUM>.

As shown in <FIG> and <FIG>, the second case unit <NUM> has the ring-shaped base <NUM>.

The base <NUM> is a plate shaped member having a thickness W71 in the rotation axis X direction.

A through hole <NUM> that penetrates the base <NUM> in the thickness direction is provided at the center of the base <NUM>.

A cylinder wall part <NUM> that surrounds the through hole <NUM> and a peripheral wall part <NUM> that surrounds the cylinder wall part <NUM> with a prescribed gap are provided at the surface on the side opposite to the first case unit <NUM> (left side in the drawing) in the base <NUM>.

A projection 73a that projects to the rotation axis X side is provided at the tip of the peripheral wall part <NUM>. The projection 73a is provided across the entire circumference in the circumferential direction around the rotation axis X.

As shown in <FIG>, three support holes 71a of the pinion shaft <NUM> are open at the outer diameter side of the peripheral wall part <NUM>. The support holes 71a are provided at prescribed intervals in the circumferential direction around the rotation axis X.

Three slits <NUM> penetrating the base <NUM> in the thickness direction are provided on the inner diameter side of peripheral wall part <NUM>.

Seen from the rotation axis X direction, the slits <NUM> form an arc shape along the inner circumference of the peripheral wall part <NUM>. The slits <NUM> are formed in a prescribed angle range in the circumferential direction around the rotation axis X.

The slits <NUM> in the second case unit <NUM> are provided at prescribed intervals in the circumferential direction around the rotation axis X. Each of the slits <NUM> is provided crossing the inner diameter side of the support hole 71a in the circumferential direction around the rotation axis X.

Three projecting walls <NUM> projecting to the paper surface front side are provided between adjacent slits <NUM>, <NUM> in the circumferential direction around the rotation axis. The projecting walls <NUM> extend in a straight line in the radial direction of the rotation axis X. The projecting walls <NUM> are provided connecting the peripheral wall part <NUM> of the outer diameter side and the cylinder wall part <NUM> of the inner diameter side.

The projecting walls <NUM> are provided at prescribed intervals in the circumferential direction around the rotation axis X. The projecting walls <NUM> are provided with a phase shift of approximately <NUM> degrees in the circumferential direction around the rotation axis X with respect to the slits <NUM>.

Bolt housing parts <NUM>, <NUM> recessed at the paper surface back side are provided between support holes 71a, 71a adjacent in the circumferential direction around the rotation axis X at the outer diameter side of peripheral wall part <NUM>. These bolt housing parts <NUM>, <NUM> are provided in a positional relationship that is symmetrical with the radius line L sandwiched between. The bolt housing parts <NUM> open at an outer circumference 71c of the base <NUM>.

Bolt insertion holes <NUM> open at the inside of the bolt housing parts <NUM>. The insertion holes <NUM> penetrate the base <NUM> in the thickness direction (rotation axis X direction).

As shown in <FIG> and <FIG>, the three linking parts <NUM> projecting to the first case unit <NUM> side are provided on the surface of the first case unit <NUM> side (right side in the drawing) in the base <NUM>.

The linking parts <NUM> are provided at equal intervals in the circumferential direction around the rotation axis X. The linking parts <NUM> are formed at a width W7 in the same circumferential direction as the linking parts <NUM> of the first case unit <NUM> side.

As shown in <FIG>, a tip surface 74a of the linking part <NUM> is a flat surface orthogonal to the rotation axis X. A support groove <NUM> for supporting the pinion mate shaft <NUM> is provided on the tip surface 74a.

As shown in <FIG>, the support groove <NUM> seen from the rotation axis X direction is formed in a straight line along the radius line L of the base <NUM>. The support groove <NUM> is formed crossing the linking part <NUM> from the inner diameter side to the outer diameter side.

As shown in <FIG>, the support groove <NUM> forms a semicircle shape along the outer diameter of the pinion mate shaft <NUM>.

As shown in <FIG>, the support groove <NUM> is formed at a depth capable of housing half of the cylindrical pinion mate shaft <NUM>. Specifically, the support groove <NUM> is formed at a depth corresponding to half the diameter Da (= Da/<NUM>) of the pinion mate shaft <NUM>.

An arc part <NUM> is provided along the outer circumference of the pinion mate gear <NUM> on the inner diameter side (rotation axis X side) of the linking part <NUM>.

In the arc part <NUM>, the outer circumference of the pinion mate gear <NUM> is supported with the spherical washer <NUM> interposed (see <FIG> and <FIG>).

An oil groove <NUM> facing along the radius line L noted above is provided in the arc part <NUM>. The oil groove <NUM> is provided in a range from the support groove <NUM> of the pinion mate shaft <NUM> to the base <NUM> positioned at the inner circumference of the linking part <NUM>.

The oil groove <NUM> connects with an oil groove <NUM> provided in a front surface 71b of the base <NUM>. The oil groove <NUM> seen from the rotation axis X direction is provided along the radius line L, and is formed to the through hole <NUM> provided in the base <NUM>.

The ring-shaped washer <NUM> that supports the back surface of the side gear 54B is placed on the front surface 71b of the base <NUM>. A cylindrical cylinder wall part <NUM> is provided on the back surface of the side gear 54B. The washer <NUM> is externally fitted on the cylinder wall part <NUM>.

An oil groove <NUM> is formed at the position intersecting the oil groove <NUM> on the inner circumference of the cylinder wall part <NUM> surrounding the though hole <NUM>. The oil groove <NUM> is provided facing along the rotation axis X across the entire length of the rotation axis X direction of the cylinder wall part <NUM> on the inner circumference of the cylinder wall part <NUM>.

As shown in <FIG> and <FIG>, the guide unit <NUM> is provided between linking parts <NUM>, <NUM> adjacent in the circumferential direction around the rotation axis X at the base <NUM> of the second case unit <NUM>. The guide unit <NUM> projects to the first case unit <NUM> side (paper surface front side).

The guide unit <NUM> forms a cylinder seen from the rotation axis X direction. The guide unit <NUM> surrounds the support hole 71a provided in the base <NUM>. The outer circumference part of the guide unit <NUM> is cut along the outer circumference 71c of the base <NUM>.

As shown in <FIG> and <FIG>, in the cross section view along the axis line X1, the pinion shaft <NUM> is inserted from the first case unit <NUM> side in the support hole 71a of the guide unit <NUM>. The pinion shaft <NUM> is positioned by the positioning pin P in a state with the rotation around the axis line X1 regulated.

In this state, the small diameter gear part <NUM> of the stepped pinion gear <NUM> externally fitted on the pinion shaft <NUM> abuts the guide unit <NUM> from the axis line X1 direction with the washer Wc sandwiched between.

As shown in <FIG>, in the differential case <NUM>, a bearing B2 is externally fitted on the cylinder wall part <NUM> of the second case unit <NUM>. The bearing B2 that is externally fitted on the cylinder wall part <NUM> is held by a support unit <NUM> of the fourth box <NUM>. The cylinder wall part <NUM> of the differential case <NUM> is supported to be rotatable with the fourth box <NUM> with the bearing B2 interposed.

The drive shaft 9B that penetrates an opening 145a of the fourth box <NUM> is inserted from the rotation axis X direction in the support unit <NUM>. The drive shaft 9B is supported to be rotatable with the support unit <NUM>.

The lip seal RS is fixed to the inner circumference of the opening 145a. The lip section (not illustrated) of the lip seal RS is elastically in contact with the outer circumference of the cylinder wall part <NUM> of the side gear 54B externally fitted on the drive shaft 9B. As a result, the gap between the outer circumference of the cylinder wall part <NUM> of the side gear 54B and the inner circumference of the opening 145a is sealed.

The first case unit <NUM> of the differential case <NUM> is supported by the plate member <NUM> with the bearing B3 that is externally fitted on the cylinder wall part <NUM> interposed (see <FIG>).

The drive shaft 9A that penetrates the insertion hole 130a of the third box <NUM> is inserted from the rotation axis direction inside the first case unit <NUM>.

The drive shaft 9A is provided crossing 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 rotation axis X direction.

As shown in <FIG>, in the interior of the differential case <NUM>, side gears 54A, 54B are spline fitted at the outer circumference of the tip end part of the drive shafts <NUM> (9A, 9B). The side gears 54A, 54B and drive shafts <NUM> (9A, 9B) are linked to be able to rotate integrally around the rotation axis X.

In this state, the side gears 54A, 54B are arranged facing with a gap open in the rotation axis X direction. The linking part <NUM> of the pinion mate shaft <NUM> is positioned between the side gears 54A, 54B.

In the present embodiment, the total of three pinion mate shafts <NUM> extend radially outside from the linking part <NUM>. A pinion mate gear <NUM> is supported on each of the pinion mate shafts <NUM>. The pinion mate gears <NUM> are assembled in a state with the teeth mutually engaged on the side gear 54A positioned at one side in the rotation axis X direction and the side gear 54B positioned at the other side.

As shown in <FIG>, the oil OL for lubrication is retained inside the fourth box <NUM>. The bottom side of the differential case <NUM> is positioned within the retained oil OL.

In the present embodiment, when the linking beam <NUM> is positioned at the bottommost side, the oil OL is retained up to the height at which the linking beam <NUM> is positioned within the oil OL.

When the output rotation of the motor <NUM> is transmitted, the retained oil OL is scooped up by the differential case <NUM> that rotates around the rotation axis X.

<FIG> are drawings for explaining the oil catch unit <NUM>.

<FIG> is a plan view of the fourth box <NUM> seen from the third box <NUM> side.

<FIG> is a perspective view of the oil catch unit <NUM> shown in <FIG> seen from diagonally above.

<FIG> is a plan view of the fourth box <NUM> seen from the third box <NUM> side. <FIG> is a drawing showing the state with the differential case <NUM> arranged.

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

<FIG> is a schematic diagram for explaining the positional relationship between the oil catch unit <NUM> and the differential case <NUM> (first case unit <NUM>, second case unit <NUM>) when the power transmission device <NUM> is seen from above.

<FIG> is a drawing of a catch unit <NUM> seen from above.

<FIG> is a cross section view of A-A in <FIG>, and is a drawing for explaining the incline of an inclined part <NUM>.

<FIG> is a cross section view of B-B in <FIG>, and is a drawing for explaining the incline of an inclined part <NUM>. In <FIG>, the incline of the inclined part <NUM> and the inclined part <NUM> are shown exaggerated, and parts other than the inclined parts are omitted as appropriate.

In <FIG> and <FIG>, to make the position of the junction part <NUM> of the fourth box <NUM> and the support wall part <NUM> clear, these are shown marked by cross hatching.

As shown in <FIG>, the support wall part <NUM> surrounding the center opening 145a with a prescribed gap is provided in the fourth box <NUM> seen from the rotation axis X direction. The inside (rotation axis X) side of the support wall part <NUM> is a housing unit <NUM> of the differential case <NUM> (see <FIG>).

A space of the oil catch unit <NUM> and a space of a breather chamber <NUM> are formed above a horizontal line HL that passes through the rotation axis X inside the fourth box <NUM>. Here, the horizontal line HL is the horizontal line HL with the installation state of the power transmission device <NUM> in the vehicle as reference. Seen from the rotation axis X direction, the horizontal line HL is orthogonal to the rotation axis X.

In the support wall part <NUM> of the fourth box <NUM>, a communication port <NUM> that communicates between the oil catch unit <NUM> and the housing unit <NUM> of the differential case <NUM> is provided in the region intersecting a vertical line VL. The communication port <NUM> is formed as a notch in the support wall part <NUM> as a ring gear support part.

As shown in <FIG>, the oil catch unit <NUM> and the breather chamber <NUM> are respectively positioned at one side (left side in the drawing) and the other side (right side in the drawing) sandwiching the vertical line VL that is orthogonal to the rotation axis X.

The oil catch unit <NUM> is arranged at a position offset from the vertical line VL passing through the rotation center of the differential case <NUM> (rotation axis X). As shown in <FIG>, when viewing the oil catch unit <NUM> from above, the oil catch unit <NUM> is arranged at a position offset from directly above the differential case <NUM>.

Here, the vertical line VL is a vertical line VL with the installation state of the power transmission device <NUM> in the vehicle as reference. Seen from the rotation axis X direction, the vertical line VL is orthogonal to the rotation axis X and the horizontal line HL.

As shown in <FIG>, the oil catch unit <NUM> is formed extending to the paper surface back side from the support wall part <NUM>. A support stand <NUM> as a shelf part projecting to the paper surface front side is provided on the bottom edge of the oil catch unit <NUM>. The support stand <NUM> is provided on the paper surface front side from the support wall part <NUM>, and in a range to the paper surface back side from the junction part <NUM> of the fourth box <NUM>.

As shown in <FIG>, seen from the rotation axis X direction, the communication port <NUM> is formed with a portion of the support wall part <NUM> cut out on the vertical line VL side (right side in the drawing) of the oil catch unit <NUM>. The communication port <NUM> communicates between the oil catch unit <NUM> and the housing unit <NUM> of the differential case <NUM>. By the communication port <NUM> being formed, the support wall part <NUM> forms a C shape when seen from the rotation axis X direction.

Seen from the rotation axis X direction, the communication port <NUM> is provided in a range crossing the vertical line VL from the breather chamber <NUM> side (right side in the drawing) to the oil catch unit <NUM> side (left side in the drawing).

The communication port <NUM> is provided at a position adjacent to the support stand <NUM> provided on the oil catch unit <NUM> in the circumferential direction around the rotation axis X. As a result, the oil OL scooped up by the differential case <NUM> more easily enters the support stand <NUM> from the communication port <NUM>.

As shown in <FIG>, in the present embodiment, during forward travel of the vehicle in which the power transmission device <NUM> is mounted, seen from the third box <NUM> side, the differential case <NUM> rotates in the counterclockwise direction CCW around the rotation axis X.

For that reason, the oil catch unit <NUM> is positioned at the downstream side in the rotation direction of the differential case <NUM>. For the width in the circumferential direction of the communication port <NUM>, the left side sandwiching the vertical line VL is wider than the right side. The left side sandwiching the vertical line VL is at the downstream side in the rotation direction of the differential case <NUM>, and the right side is the upstream side. As a result, much of the oil OL scooped up by the differential case <NUM> rotating around the rotation axis X is made to be able to flow into the oil catch unit <NUM>.

Furthermore, as shown in <FIG>, the outer circumference position of the rotational orbit of a second shaft part <NUM> and the outer circumference position of the rotational orbit of the large diameter gear part <NUM> are offset in the radial direction of the rotation axis X. The outer circumference position of the rotational orbit of the second shaft part <NUM> is positioned more to the inner diameter side than the outer circumference position of the rotational orbit of the large diameter gear part <NUM>. For that reason, there is a spatial margin at the outer diameter side of the second shaft part <NUM>. By providing the oil catch unit <NUM> using this space, it is possible to effectively use the space inside the body box <NUM>.

Also, the second shaft part <NUM> projects to the back side of the small diameter gear part <NUM> seen from the motor <NUM>. The peripheral member of the second shaft part <NUM> (e.g. the guide unit <NUM> of the differential case <NUM> that supports the second shaft part <NUM>) is at a position near the oil catch unit <NUM>.

Thus, it is possible to smoothly perform supplying of the oil OL (lubricating oil) from that peripheral member to the oil catch unit <NUM>.

As shown in <FIG>, an oil hole 151a that is open facing upward is provided at the back side of the support stand <NUM>. The oil hole 151a extends from the end part of the outer diameter side open at the top surface of the support stand <NUM> to the inner diameter side inside the fourth box <NUM>. The end part of the inner diameter side of the oil hole 151a is open on the inner circumference of the support unit <NUM>.

As shown in <FIG>, the end part of the inner diameter side of the oil hole 151a in the support unit <NUM> is open between the lip seal RS and the bearing B2.

As shown in <FIG>, an oil guide <NUM> is placed on the support stand <NUM>. The oil guide <NUM> is provided as a catch member for the oil OL on the top part of the support stand <NUM> (shelf part). The oil guide <NUM> has a catch unit <NUM>, and a guide unit <NUM> extending from the catch unit <NUM> to the first box <NUM> side (paper surface front side).

As shown in <FIG>, seen from above, the support stand <NUM> is provided radially outside the rotation axis X, at a position partially overlapping the differential case <NUM> (first case unit <NUM>, second case unit <NUM>), and to avoid interference with the stepped pinion gear <NUM> (large diameter gear part <NUM>).

Seen from the radial direction of the rotation axis X, the catch unit <NUM> is provided at a position overlapping the second shaft part <NUM> of the pinion shaft <NUM>. Furthermore, the guide unit <NUM> is provided at a position where the first shaft part <NUM> of the pinion shaft <NUM> and the large diameter gear part <NUM> overlap.

For that reason, when the differential case <NUM> rotates around the rotation axis X, the oil OL scooped up by the differential case <NUM> moves toward the catch unit <NUM> and the guide unit <NUM> side.

As shown in <FIG>, the catch unit <NUM> is configured from the inclined part <NUM> as a second inclined surface and the inclined part <NUM> as a first inclined surface. The inclined part <NUM> is positioned at the back side of the support stand <NUM> (upper side in <FIG>) and is connected to the oil hole 151a. The inclined part <NUM> is positioned at the front side of the support stand <NUM> (lower side of <FIG>) and is connected to the guide unit <NUM>. The inclined part <NUM> communicates with the inclined part <NUM> at one end 157a.

The inclined part <NUM> extends from one end 156a connected to the oil hole 151a toward another end 156b in the direction orthogonal to the rotation axis X. As shown in <FIG>, the surface of the inclined part <NUM> is inclined downward facing the one end 156a from the other end 156b.

As shown in <FIG>, the inclined part <NUM> extends from the one end 157a toward another end 157b in the direction along the rotation axis X. The one end 157a of the inclined part <NUM> communicates with the inclined part <NUM>, and the other end 157b is connected to the guide unit <NUM>. As shown in <FIG>, the surface of the inclined part <NUM> is inclined downward from the one end 157a toward the other end 157b.

As shown in <FIG>, a wall part 153a stands on the outer circumference edge of the inclined part <NUM> and the inclined part <NUM> of the catch unit <NUM>. The wall part 153a extends in the direction separating from the support stand <NUM> (upward). A portion of the oil OL caught by the catch unit <NUM> is held and retained in the oil guide <NUM> by the wall part 153a.

The surface of the inclined part <NUM> and the inclined part <NUM> is each inclined. As a result, as shown in <FIG>, a portion of the oil OL caught by the inclined part <NUM> flows toward the oil hole 151a according to gravity. A portion of the oil OL caught by the inclined part <NUM> flows toward the guide unit <NUM> according to gravity.

As shown in <FIG>, a notch part <NUM> is provided in the wall part 153a extending from the one end 156a of the inclined part <NUM>.

The notch part <NUM> is provided in a region facing the oil hole 151a. A portion of the oil OL that flows toward the oil hole 151a is discharged from the notch part <NUM> part toward the oil hole 151a. Specifically, the notch part <NUM> acts as an introduction port to guide the oil OL to the oil hole 151a.

Here, as shown in <FIG>, an inclination angle α with respect to the horizontal line HL is smaller than an inclination angle β with respect to the horizontal line HL of the inclined part <NUM>. Specifically, the inclined part <NUM> has a gentler incline than the inclined part <NUM>. The opening surface of the oil hole 151a is smaller than the surface of the guide unit <NUM>. For that reason, the oil discharge amount of the oil hole 151a is smaller than that of the guide unit <NUM>. For that reason, in the embodiment, the incline of the inclined part <NUM> connected to the oil hole 151a is made to be gentle, suppressing the amount of oil OL flowing to the oil hole 151a. By matching the amount of oil OL flowing into the oil hole 151a to the discharge amount of the oil OL from the oil hole 151a, it is possible to keep a suitable amount of the oil OL retained in the catch unit <NUM>.

The guide unit <NUM> is inclined downward as it separates from the catch unit <NUM>. As shown in <FIG>, wall parts 154a, 154a are provided at both sides in the width direction of the guide unit <NUM>. The wall parts 154a, 154a are provided across the entire length in the lengthwise direction of the guide unit <NUM>. The wall parts 154a, 154a are connected to the wall part 153a that surrounds the outer circumference of the catch unit <NUM>.

As shown in <FIG>, a portion of the oil OL retained in the inclined part <NUM> of the catch unit <NUM> is discharged to the guide unit <NUM> side. Specifically, the guide unit <NUM> acts as a branch port and branches a portion of the oil OL retained in the catch unit <NUM> and guides it to a location other than the oil hole 151a.

As shown in <FIG>, in the guide unit <NUM>, the position that avoids interference with the differential case <NUM> extends to the second box <NUM> side. A tip 154b of the guide unit <NUM> faces a through hole 126a provided on the wall part <NUM> of the second box <NUM> with a gap open in the rotation axis X direction.

A boss part <NUM> that surrounds the through hole 126a is provided on the outer circumference of the wall part <NUM>. One end of a pipe <NUM> is fitted into the boss part <NUM> from the rotation axis X direction.

The pipe <NUM> passes through the outside of the second box <NUM> to the third box <NUM>. The other end of the pipe <NUM> communicates with the oil hole 136a provided in the cylindrical connecting wall <NUM> of the third box <NUM> (see <FIG>).

A portion of the oil OL scooped up by the differential case <NUM> rotating around the rotation axis X reaches the oil catch unit <NUM>. The oil OL passes through the guide unit <NUM> and the pipe <NUM>, and is supplied to the internal space Sc of the connecting wall <NUM>.

A radial oil passage <NUM> that communicates with the internal space Sc is provided in the third box <NUM>.

The radial oil passage <NUM> extends radially downward from the internal space Sc. The radial oil passage <NUM> communicates with the axial oil passage <NUM> provided inside the junction part <NUM>.

The axil oil passage <NUM> connects with the oil reservoir <NUM> provided at the bottom of the second box <NUM> via the communication hole 112a provided in the junction part <NUM> of the first box <NUM>.

The oil reservoir <NUM> penetrates inside the peripheral wall part <NUM> in the rotation axis X direction. The oil reservoir <NUM> connects with the second gear chamber Sb2 provided in the fourth box <NUM>.

The operation of the power transmission device <NUM> of this configuration is explained.

As shown in <FIG>, in the power transmission device <NUM>, the planetary reduction gear <NUM>, the differential device <NUM>, and the drive shafts <NUM> (9A, 9B) are provided along the transmission route of the output rotation of the motor <NUM>.

As shown in <FIG>, when the rotor core <NUM> rotates around the rotation axis X by driving of the motor <NUM>, the rotation is inputted to the sun gear <NUM> of the planetary reduction gear <NUM> via the motor shaft <NUM> that rotates integrally with the rotor core <NUM>.

As shown in <FIG>, with the planetary reduction gear <NUM>, the sun gear <NUM> serves as the input unit of the output rotation of the motor <NUM>. The differential case <NUM> that supports the stepped pinion gear <NUM> serves as the output unit of the inputted rotation.

When the sun gear <NUM> rotates around the rotation axis X by the inputted rotation, the stepped pinion gear <NUM> (large diameter gear part <NUM>, small diameter gear part <NUM>) rotates around the axis line X1 by the rotation inputted from the sun gear <NUM> side.

Here, the small diameter gear part <NUM> of the stepped pinion gear <NUM> is engaged with the ring gear <NUM> fixed to the inner circumference of the fourth box <NUM>. For that reason, the stepped pinion gear <NUM> revolves around the rotation axis X while auto-rotating around the axis line X1. The rotation axis X is the revolution center of the stepped pinion gear <NUM> (pinion gear).

Here, with the stepped pinion gear <NUM>, the outer diameter R2 of the small diameter gear part <NUM> is smaller than the outer diameter R1 of the large diameter gear part <NUM> (see <FIG>).

By doing this, the differential case <NUM> (first case unit <NUM>, second case unit <NUM>) that supports the stepped pinion gear <NUM> rotates around the rotation axis X at a rotation speed lower than the rotation inputted from the motor <NUM> side.

For that reason, the rotation inputted to the sun gear <NUM> of the planetary reduction gear <NUM> is significantly reduced by the stepped pinion gear <NUM>. The reduced rotation is outputted to the differential case <NUM> (differential mechanism <NUM>).

By the differential case <NUM> rotating around the rotation axis X by the inputted rotation, inside the differential case <NUM>, the drive shafts <NUM> (9A, 9B) that engage with the pinion mate gear <NUM> rotate around the rotation axis X. As a result, drive wheels (not illustrated) at the left and right of the vehicle in which the power transmission device <NUM> is mounted rotate by the transmitted rotational drive power.

As shown in <FIG>, the oil OL for lubrication is retained inside the fourth box <NUM>. For that reason, the retained oil OL is scooped up by the differential case <NUM> rotating around the rotation axis X during transmission of the output rotation of the motor <NUM>.

The engagement part between the sun gear <NUM> and the large diameter gear part <NUM>, the engagement part between the small diameter gear part <NUM> and the ring gear <NUM>, and the engagement part between the pinion mate gear <NUM> and the side gears 54A, 54B are lubricated by the scooped-up oil OL.

As shown in <FIG>, the differential case <NUM> seen from the third box <NUM> side rotates in the counterclockwise direction CCW around the rotation axis X.

The oil catch unit <NUM> is provided on the top part of the fourth box <NUM>. The oil catch unit <NUM> is positioned at the downstream side in the rotation direction of the differential case <NUM>. Much of the oil OL scooped up by the differential case <NUM> flows into the oil catch unit <NUM>.

As shown in <FIG>, the oil guide <NUM> mounted on the support stand <NUM> is provided in the oil catch unit <NUM>.

The guide unit <NUM> and the catch unit <NUM> of the oil guide <NUM> are positioned at the radial outside of the first case unit <NUM> of the differential case <NUM> and the radial outside of the second case unit <NUM> of the differential case <NUM>.

For that reason, much of the oil that is scooped up by the differential case <NUM> and flows into the oil catch unit <NUM> is captured by the oil guide <NUM>.

A portion of the oil OL captured by the inclined part <NUM> of the oil guide <NUM> flows along the incline to the oil hole 151a side. The oil OL is discharged from the notch part <NUM> provided in the wall part 153a, and flows into the oil hole 151a for which one end is opened on the top surface of the support stand <NUM>.

The end part of the inner diameter side of the oil hole 151a is open at the inner circumference of the support unit <NUM> (see <FIG>). For that reason, the oil OL that flows into the oil hole 151a is discharged to a gap Rx between the inner circumference of the support unit <NUM> of the fourth box <NUM> and the cylinder wall part <NUM> of the side gear 54B.

A portion of the oil OL discharged to the gap Rx lubricates the bearing B2 supported by the support unit <NUM>. The oil OL that lubricates the bearing B2 moves to the outer diameter side by the centrifugal force by rotation of the differential case <NUM>. On the outer diameter side of the differential case <NUM>, the slit <NUM> is provided along the inner circumference of the peripheral wall part <NUM>. Further movement of the oil OL to the outer diameter side is obstructed by the peripheral wall part <NUM>. The oil OL passes through the slit <NUM> to the first case unit <NUM> side.

At the first case unit <NUM> side of the slit <NUM>, the case-internal oil passage <NUM> is open in the inner circumference of the guide unit <NUM>. A portion of the oil OL that passes through the slit <NUM> flows inside the case-internal oil passage <NUM> by the centrifugal force by the rotation of the differential case <NUM>.

The oil OL that flows into the case-internal oil passage <NUM> passes through the introduction path <NUM> and flows into the shaft-internal oil passage <NUM> of the pinion shaft <NUM>. The oil OL that flows into the shaft-internal oil passage <NUM> is discharged radially outside from the oil holes <NUM>, <NUM>. The discharged oil OL lubricates the needle bearing NB externally fitted on the pinion shaft <NUM>.

Furthermore, a portion of the oil OL discharged to the gap Rx passes through the oil groove <NUM> provided on the inner circumference of the cylinder wall part <NUM> of the second case unit <NUM> as shown in <FIG> and <FIG>. The oil OL that passes through the oil groove <NUM> is supplied to the washer <NUM> that supports the back surface of the side gear 54B and lubricates the washer <NUM>.

Furthermore, the oil OL passes through the oil groove <NUM> provided in the base <NUM> of the second case unit <NUM> and the oil groove <NUM> provided in the arc part <NUM>. The oil OL that passes through the oil groove <NUM> is supplied to the spherical washer <NUM> that supports the back surface of the pinion mate gear <NUM> and lubricates the spherical washer <NUM>.

Also, as shown in <FIG>, a portion of the oil OL captured by the inclined part <NUM> of the oil guide <NUM> of the oil catch unit <NUM> flows along the incline to the guide unit <NUM> side. The oil OL further flows along the incline of the guide unit <NUM>. As shown in <FIG>, the tip 154b of the guide unit <NUM> faces the through hole 126a provided in the wall part <NUM> of the second box <NUM> with a gap open in the rotation axis X direction.

For that reason, much of the oil OL that flows to the guide unit <NUM> flows into the through hole 126a of the second box <NUM>.

The boss part <NUM> surrounding the through hole 126a is provided on the outer circumference of the wall part <NUM>. One end of the pipe <NUM> is fitted into the boss part <NUM> from the rotation axis X direction.

The pipe <NUM> passes through the outside of the second box <NUM> and extends to the third box <NUM>. The other end of the pipe <NUM> communicates with the oil hole 136a provided in the cylindrical connecting wall <NUM> of the third box <NUM> (see <FIG>).

For that reason, in the present embodiment, a portion of the oil OL that reaches the oil catch unit <NUM> passes through the guide unit <NUM> and the pipe <NUM> and is supplied to the internal space Sc of the connecting wall <NUM>.

The oil OL discharged from the oil hole 136a to the internal space Sc is retained in the internal space Sc. The oil OL lubricates the bearing B4 supported by the peripheral wall part <NUM> of the third box <NUM>.

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

As shown in <FIG>, the other end 20b of the motor shaft <NUM> is inserted inside the cylinder wall part <NUM> of the side gear 54A. A connection path <NUM> that communicates with the back surface of the side gear 54A is provided on the inner circumference of the cylinder wall part <NUM>.

For that reason, a portion of the oil OL that moves to the other end 20b side of the motor shaft <NUM> and is discharged to inside the cylinder wall part <NUM> passes through the connection path <NUM>. The oil OL that passes through the connection path <NUM> is supplied to the washer <NUM> of the back surface of the side gear 54A and lubricates the washer <NUM>.

Furthermore, the oil OL that lubricates the washer <NUM> of the back surface of the side gear 54A passes through the oil groove <NUM> provided on the gear support part <NUM> of the first case unit <NUM> and the oil groove <NUM> provided on the arc part <NUM>. The oil OL that passes through the oil groove <NUM> is supplied to the spherical washer <NUM> that supports the back surface of the pinion mate gear <NUM> and lubricates the spherical washer <NUM>.

Also, as shown in <FIG>, the internal space Sc of the third box <NUM> connects with the second gear chamber Sb2 provided in the fourth box <NUM> via the radial oil passage <NUM>, the axial oil passage <NUM>, the communication hole 112a, and the oil reservoir <NUM> provided at the bottom of the second box <NUM>.

For that reason, the oil OL inside the internal space Sc is held at a position at the same height at which the oil OL is retained inside the fourth box <NUM>.

In this way, much of the oil OL scooped up by the differential case <NUM> rotating around the rotation axis X flows into the oil catch unit <NUM>. The oil OL is supplied from the oil catch unit <NUM> to inside the support unit <NUM> of the fourth box <NUM> and lubricates the bearing B2. The oil OL is also supplied from the oil catch unit <NUM> to the internal space Sc inside the third box <NUM> and lubricates the bearing B4.

Also, the oil OL that lubricates these bearings B2, B4 is ultimately returned to inside the fourth box <NUM>, and scooped up by the rotating differential case <NUM>.

Thus, in the power transmission device <NUM>, the oil OL inside the fourth box <NUM> is scooped up during rotation of the drive wheels W, W, and is used for lubrication of the bearings and engagement parts between gears with each other. The oil OL used for lubrication is returned to inside the fourth box <NUM> and made to be able to be scooped up again.

As described above, the power transmission device <NUM> of the present embodiment has the following configuration.

The oil OL scooped up by the rotation of the stepped pinion gear <NUM> is caught on the upper side of the support stand <NUM>, in other words, the surface of the support stand <NUM>, or in the oil guide <NUM> placed on the support stand <NUM>. As a result, it is possible for the oil OL to be sent into various locations from the upper side of the support stand <NUM>. Specifically, by providing the support stand <NUM>, it is possible to increase the degree of freedom in designing the supply of the oil OL scooped up by the rotation of the stepped pinion gear <NUM>.

(<NUM>) The support stand <NUM> has the oil hole 151a that opens facing upward.

The oil OL scooped up by the rotation of the stepped pinion gear <NUM> and has fallen onto the upper side of the support stand <NUM> is introduced to the oil hole 151a that is open upward. This configuration makes it possible to guide the oil OL more efficiently to the oil hole 151a than in a configuration in which it is introduced from the oil hole 151a open facing sideways.

(<NUM>) The power transmission device <NUM> has the oil guide <NUM> (catch member) provided on the top part of the support stand <NUM>. The notch part <NUM> (introduction port) that guides the oil OL to the oil hole 151a is provided on the oil guide <NUM>.

When the oil OL is caught by the oil guide <NUM> provided on the top part of the support stand <NUM>, using gravity, the oil OL is introduced from the notch part <NUM> to the oil hole 151a provided in the support stand <NUM>. With this configuration, it is possible to use the oil OL efficiently. With the embodiment, the notch part <NUM> is provided as an introduction port, but the form of the introduction port is not limited. For example, the introduction port can also be an oil hole provided on the bottom part or the side surface of the oil guide <NUM>.

(<NUM>) In the oil guide <NUM>, the guide unit <NUM> (branch port) that guides the oil OL to a location other than the oil hole 151a is provided.

The amount of the oil OL that can pass through the oil hole 151a formed on the oil guide <NUM> is smaller than the volume of the oil OL that can be caught by the oil guide <NUM>. For that reason, the surplus oil OL caught by the oil guide <NUM> is branched by the guide unit <NUM> and used for lubrication of other locations. With this configuration, it is possible to use the oil OL effectively.

(<NUM>) The oil guide <NUM> has the inclined part <NUM> (first inclined surface) connected to the guide unit <NUM>, and the inclined part <NUM> (second inclined surface) connected to the notch part <NUM>. The inclination angle α of the inclined part <NUM> is smaller than the inclination angle β of the inclined part <NUM>.

The oil OL flows according to gravity by the two inclined parts <NUM>, <NUM>, so it is possible to guide the oil OL smoothly to the notch part <NUM> and the guide unit <NUM> that the inclined parts <NUM>, <NUM> are connected to. Furthermore, the inclination angle α of the inclined part <NUM> connected to the notch part <NUM> is made gentler than the incline angle β of the inclined part <NUM>. As a result, in the inclined part <NUM>, the oil OL does not immediately flow to the notch part <NUM>, and is temporarily held on the inclined part <NUM>. By using this configuration, it is possible to increase the oil OL holding function in the catch unit <NUM> of the oil guide <NUM>.

(<NUM>) The power transmission device <NUM> has the ring gear <NUM> that engages with the stepped pinion gear <NUM>. The fourth box <NUM> has the support wall part <NUM> (ring gear support part) that engages with the ring gear <NUM>. The support wall part <NUM> has the communication port <NUM> (notch) at a position adjacent to the support stand <NUM> in the circumferential direction.

By providing the communication port <NUM> on the support wall part <NUM> that engages with the ring gear <NUM>, it is possible to supply the oil OL to the support stand <NUM> more smoothly. In specific terms, a portion of the oil OL that scatters by the rotation of the stepped pinion gear <NUM> jumps over the outer circumference side of the ring gear <NUM> and scatters in the direction facing the support stand <NUM>. The support wall part <NUM> that engages with the ring gear <NUM> can obstruct the oil OL facing the support stand <NUM>. In light of that, the communication port <NUM> is provided in the support wall part <NUM>, and guides the oil OL to the support stand <NUM>. Forming a notch as the communication port <NUM>, said another way, means that the support wall part <NUM> that engages with the ring gear <NUM> is arranged at both sides sandwiching the notch. Specifically, the configuration of the embodiment means a configuration that increases the stability of the support of the ring gear <NUM>.

(<NUM>) The support wall part <NUM> has a shape of the letter C.

The support wall part <NUM> may also be configured from a plurality of individual support parts arranged on the outer circumference of the ring gear <NUM>, for example. However, by forming the support wall part <NUM> in a C shape seen from the rotation axis X direction, making a shape that surrounds the outer circumference of the ring gear <NUM> as shown in the embodiment, it is possible to increase the surface of the portion that supports the ring gear <NUM>. By using this configuration, it is possible to increase the support stability of the ring gear <NUM>.

The power transmission device <NUM> of the present embodiment has the following configuration.

(<NUM>) The power transmission device (<NUM>) has the motor <NUM> arranged upstream of the transmission route of the rotation drive force of the sun gear <NUM> that engages with the stepped pinion gear <NUM>, and the drive shaft 9A (drive shaft) connected to the differential mechanism <NUM>. The drive shaft 9A penetrates the inner circumference of the sun gear <NUM> and the motor <NUM>.

The power transmission device <NUM> is the power transmission device for a single axle electric vehicle, and can provide a compact power transmission device.

Claim 1:
A power transmission device (<NUM>) comprising:
a box (<NUM>);
a case (<NUM>) disposed in the box (<NUM>);
a differential mechanism (<NUM>) housed in the case (<NUM>); and
a planetary gear mechanism (<NUM>) disposed in the box (<NUM>) and supported by the case (<NUM>), the planetary gear mechanism (<NUM>) including a sun gear (<NUM>) and a pinion gear (<NUM>) that engages with the sun gear (<NUM>), wherein
the box (<NUM>) has a shelf part (<NUM>) above a horizontal line (HL) that passes through a revolution center (X) of the pinion gear (<NUM>), and
the shelf part (<NUM>) is arranged at a position that does not overlap the sun gear (<NUM>) when viewed from radially above and that does not overlap the sun gear (<NUM>) when viewed in the direction of the horizontal line (HL),
characterized in that
the shelf part (<NUM>) is configured to catch oil (OL) that is scooped by the pinion gear (<NUM>) and, seen from above, is radially outside the revolution center (X).