CN111503251A

CN111503251A - Lubricating structure of differential device

Info

Publication number: CN111503251A
Application number: CN201911411175.0A
Authority: CN
Inventors: 园田浩一
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 2019-01-31
Filing date: 2019-12-31
Publication date: 2020-08-07
Also published as: JP2020122531A

Abstract

A lubricating structure of a differential device (1) is configured such that lubricating oil stored in the bottom of a transmission case (2) is raised by the rotation of a main transmission gear (7) attached to a differential case (3), the raised lubricating oil is supplied into the differential case (3) via spiral grooves (5) formed in the inner peripheral surfaces of left and right inner portions (3a) of the differential case (3) to lubricate each portion, lubricating oil passages (16L, 16R) are formed in the axial direction in the inner end portions of left and right axle shafts (4L, 4R) which are inserted and supported in the left and right inner portions (3a) of the differential case (3), and the two lubricating oil passages (16L, 16R) are communicated with each other.

Description

Lubricating structure of differential device

Technical Field

The present invention relates to a lubricating structure of a differential device for distributing rotational power from a drive source of a vehicle to a pair of left and right drive wheels.

Background

A differential device (differential device) for distributing rotational power from a drive source such as an engine to a pair of left and right drive wheels is provided in a power transmission path of a vehicle. In a differential device supported rotatably about a 1 st axis in a differential case of a transmission, a pinion shaft is inserted and fixed in a direction along a 2 nd axis perpendicular to the 1 st axis, and the differential case accommodates: a pair of pinion gears rotatably supported by the pinion shaft; and a pair of side gears that are engaged with the respective pinions and are supported to be rotatable about the 1 st axis. The left and right side gears are coupled to outer peripheries of inner ends of the left and right axles facing the inside of the differential case.

In such a differential device, it is preferable to supply lubricating oil into the differential case in order to prevent a reduction in durability due to power loss or wear caused by friction between the pair of pinions and the side gears that mesh with each other in the differential case. Therefore, various lubricating structures of differential devices have been proposed.

For example, patent documents 1 to 3 propose the following lubricating structure: the lubricating oil stored in the bottom portion of the transmission case is lifted by the rotation of the final gear attached to the differential case, and the lifted lubricating oil is supplied into the differential case through the spiral groove formed in any one of the inner peripheral surface of the inner side portion of the differential case and the outer periphery of the inner end portion of the axle shaft, so that each portion is lubricated.

Patent document 4 proposes a lubricating structure as follows: the differential case is provided with a housing portion having a guide plate for guiding and collecting the lubricating oil lifted by the main transmission gear, and the lubricating oil collected by the housing portion is supplied into the differential case via a lubricating oil flow path to lubricate each portion.

Patent document 5 proposes a lubrication structure including: a 1 st oil groove and a 2 nd oil groove are formed on the left and right sides of the differential case, respectively, and lubricating oil supplied from a supply pipe is supplied into the differential case via the 1 st oil groove and the 2 nd oil groove, respectively, to lubricate each part.

Documents of the prior art

Patent document

Patent document 1: japanese Kokai publication Sho 58-150650

Patent document 2: japanese laid-open patent publication No. 11-118028

Patent document 3: japanese patent laid-open No. 2008-115987

Patent document 4: japanese Kokai publication Sho 62-194242

Patent document 5: japanese Utility model registration No. 2606235

Disclosure of Invention

Problems to be solved by the invention

However, in the lubrication structures proposed in patent documents 1 to 5, since the supply amount of the lubricating oil kicked up by the final gear and the like varies and varies in the right and left sides in the differential case depending on the vehicle speed, the oil temperature and the like, the amount of the lubricating oil is insufficient in either the right or left side, and therefore, there is a possibility that the gears are burned or worn.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a lubricating structure of a differential device capable of preventing the occurrence of seizure and wear of gears by uniformly supplying lubricating oil to the left and right sides in a differential case.

Means for solving the problems

In order to achieve the above object, the present invention is a lubrication structure of a differential device 1 in which end portions of left and

right axles

4L, 4R are rotatably inserted and supported through left and right inner side portions 3a of a differential case 3 rotatably supported by a transmission case 2, respectively, lubricating oil stored in a bottom portion of the transmission case 2 is kicked up by rotation of a main transmission gear 7 mounted to the differential case 3, and the kicked-up lubricating oil is supplied into the differential case 3 for lubrication of each portion through a spiral groove 5 formed in either one of inner peripheral surfaces of the left and right inner side portions 3a of the differential case 3 and an outer periphery of an inner end portion of the

axle

4L, 4R, characterized in that lubricating oil passages L, 16R are formed in axial directions of inner end portions of the left and right inner side portions 3a of the differential case 3 through which the left and

right axles

4L, 4R are inserted and supported, respectively, and the two lubricating oil passages L, 16R are communicated with each other, and the lubricating oil of the differential device is supplied into the main transmission gear case 3 through the lubricating oil passages L, the lubricating oil passages L, 367, and the lubricating oil passages L, L, 367 are communicated with each other.

According to the lubricating structure of the differential device of the present invention, since the lubricating oil passages formed in the inner end portions of the left and right axles are communicated with each other, when the left and right supply amounts of the lubricating oil kicked up by the final drive gear in the transmission are unbalanced, the lubricating oil on the side with the larger supply amount can be supplied to the side with the smaller supply amount, and the supply amount of the lubricating oil can be balanced left and right. Therefore, the lubricating oil can be supplied uniformly to the left and right in the differential case, and the occurrence of seizure and wear of the gears can be prevented.

In the lubricating structure of the differential device,

annular oil sumps

13L, 13R defined by the oil seals 12 and the bearings 6 may be formed on the left and right sides of the transmission case 2, respectively, the oil seals 12 may be fitted to the inner peripheries of left and right opening portions of the transmission case 2 through which the left and

right axles

4L, 4R pass, the bearings 6 may rotatably support the differential case 3, and the lubricating structure of the differential device may be configured to introduce the lubricating oil lifted by the main transmission gear 7 into the left and

right oil sumps

13L, 13R, respectively.

According to the structure, the lubricating oil raised by the main transmission gear drops after colliding with the inner wall of the gearbox and is collected in the left and right oil storage parts in the gearbox for lubricating each part.

In the lubricating structure of the differential device, a guide member 15 may be provided for guiding the lubricating oil lifted by the final drive gear 7 to the left and

right oil reservoirs

13L, 13R, respectively.

According to the above configuration, the lubricating oil kicked up by the final drive gear is efficiently guided to the left and right oil sumps along the guide member.

In the lubricating structure of the differential device, oil grooves 3b communicating with the left and

right oil reservoirs

13L, 13R may be formed in the end surfaces of the left and right inner portions 3a of the differential case 3, respectively, and the 1

st oil passages

19L, 19R may be formed in the end portions of the left and

right axles

4L, 4R, respectively, and the 1

st oil passages

19L, 19R may communicate the

oil passages

16L, 16R formed in the end portions of the left and

right axles

4L, 4R with the oil grooves 3 b.

According to the above configuration, the lubricating oil collected in the left and right oil reservoirs flows from the oil groove to the lubricating oil passage through the 1 st oil passage, and is supplied to lubricate each part.

In the lubricating structure of the differential device, radial 2

nd oil passages

20L and 20R may be formed in inner end portions of the left and

right axles

4L and 4R, respectively, and the 2

nd oil passages

20L and 20R may supply lubricating oil to back surfaces of the left and right side gears 11 coupled to the outer peripheries of the inner end portions.

According to the above configuration, the lubricating oil flowing from the lubricating oil passage to the 2 nd oil passage flows radially outward in the 2 nd oil passage by the centrifugal force generated by the rotation of the axle, and lubricates the back surface side of the side gear.

In the lubricating structure of the differential device, screw shafts 22 may be fitted into the lubricating

oil passages

16L and 16R formed in the inner end portions of the left and

right axles

4L and 4R, respectively, and the screw shafts 22 may rotate together with the

axles

4L and 4R to flow the lubricating oil to the inner end surfaces of the

axles

4L and 4R.

According to the above configuration, the lubricating oil is forcibly vigorously made to flow in the lubricating oil passage by the screw shaft rotating together with the axle, so that each part is lubricated.

Effects of the invention

According to the lubricating structure of the differential device of the present invention, the lubricating oil can be supplied equally to the left and right in the differential case, and the occurrence of seizure or wear of the gears can be prevented.

Drawings

Fig. 1 is a vertical cross-sectional view of a differential device having a lubricating structure according to embodiment 1 of the present invention.

Fig. 2 is an enlarged detailed view of a portion a of fig. 1.

Fig. 3 is a longitudinal sectional view of a main portion of a differential device including a lubricating structure according to embodiment 1 of the present invention.

Fig. 4 is a sectional view taken along line B-B of fig. 3.

Fig. 5 is a longitudinal sectional view of a main portion of a differential case of a differential device having a lubricating structure according to embodiment 1 of the present invention.

Fig. 6 is a perspective view of an axle of a differential device having a lubricating structure according to embodiment 1 of the present invention.

Fig. 7 is a vertical cross-sectional view of a differential device having a lubricating structure according to embodiment 2 of the present invention.

Fig. 8 is an enlarged detail view of the portion C of fig. 7.

Fig. 9 is a longitudinal sectional view of a main portion of a differential device including a lubricating structure according to embodiment 2 of the present invention.

Fig. 10 is a perspective view of a screw shaft of a differential device having a lubricating structure according to embodiment 2 of the present invention.

Description of the reference symbols

1: a differential device;

2: a gearbox;

3: a differential case;

3 a: an inner side portion of the differential case;

3 b: an oil sump of the differential case;

4L, 4R is an axle;

5: a helical groove;

6: a bearing;

7: a main drive gear;

9: a pinion shaft;

10: a pinion gear;

11: a side gear;

12: oil sealing;

13L, 13R is an oil storage part;

15: a guide member;

16L, 16R lubricating oil path;

17: a sleeve;

18: taking over a pipe;

19L, 19R is the 1 st oil way;

20L, 20R is the 2 nd oil way;

21: an oil path;

22: a screw shaft;

23: taking over a pipe;

c1: 1 st axis;

c2: the 2 nd axis.

Detailed Description

Embodiments of the present invention will be described below with reference to the drawings.

< embodiment 1>

Fig. 1 is a longitudinal sectional view of a differential device having a lubricating structure according to embodiment 1 of the present invention, fig. 2 is an enlarged detail view of a portion a of fig. 1, fig. 3 is a longitudinal sectional view of a main portion of the differential device, fig. 4 is a sectional view taken along a line B-B of fig. 3, fig. 5 is a longitudinal sectional view of a main portion of a differential case of the differential device, and fig. 6 is a perspective view of an axle of the differential device.

The differential device 1 shown in fig. 1 distributes rotational power from a drive source, not shown, such as an engine of a vehicle, to left and right drive wheels, not shown, and is housed in a transmission case 2, and the differential device 1 includes a spherical shell-shaped differential case 3 rotationally driven around a 1 st axial center C1 in the vehicle width direction (the left-right direction in fig. 1).

As shown in fig. 1, the differential case 3 is integrally provided with a cylindrical inner portion 3a projecting in the direction of the 1 st axial center C1 (the left-right direction in fig. 1), and the inner portion 3a is used for inserting and supporting the opposite small-diameter inner end portions of the left and

right axles

4L, 4R, and here, a spiral groove 5 is formed in the inner peripheral surface of each of the left and right inner portions 3a of the differential case 3 as shown in fig. 5 (only the left inner portion 3a is shown in fig. 5).

The differential case 3 is supported rotatably about the 1 st axis C1 by left and right inner portions 3a being supported by the transmission case 2 by left and right bearings (tapered roller bearings) 6. An annular flange portion 3A rising in the vertical direction in fig. 1 is integrally formed on the outer periphery of the differential case 3, and an annular main transmission gear (ring gear) 7 for inputting rotational power output from a drive source such as an engine to the differential case 3 is attached to the flange portion 3A by a plurality of bolts 8 (only one bolt is shown in fig. 1).

However, as shown in fig. 1, the pinion shaft 9 is fixedly inserted into the center portion of the differential case 3 along the 2 nd axial center C2 direction (the vertical direction in fig. 1) perpendicular to the 1 st axial center C1, and the differential case 3 accommodates therein: a pair of left and right pinions (bevel gears) 10 supported by the pinion shaft 9 to be rotatable about a 2 nd axis C2; and a pair of left and right side gears (bevel gears) 11 that are respectively meshed with the pinion gears 10 and are supported to be rotatable about the 1 st axis C1. Here, the pair of pinion gears 10 are disposed in the differential case 3 at the upper and lower sides in fig. 1, and the pair of side gears 11 are disposed on the left and right sides thereof with the pinion shaft 9 interposed therebetween.

A plurality of spline teeth (not shown) extending in the axial direction are formed on the inner peripheries of the pair of side gears 11 over the entire periphery, and these spline teeth are fitted to a plurality of axially long spline teeth 4a (only the left axle 4L is shown in fig. 6) formed on the outer peripheries of the inner ends of the left and

right axles

4L and 4R (each passing through the left and right inner portions 3a of the differential case 3), whereby the inner ends of the left and

right axles

4L and 4R are spline fitted to the central portions of the left and right side gears 11, respectively.

Further, as shown in fig. 1, circular hole-shaped opening portions 2a are formed in portions of the transmission case 2 through which the left and

right axles

4L, 4R penetrate, and oil seals 12 are fitted and mounted to the inner peripheries of these opening portions 2a, here, although not shown, lubricating oil is stored in the bottom portion of the transmission case 2, and the opening portions 2a of the transmission case 2 through which the left and

right axles

4L, 4R penetrate are sealed by the oil seals 12, respectively, so that the lubricating oil in the transmission case 2 is reliably prevented from leaking to the outside by the sealing action of these oil seals 12.

Here, the lubricating structure of the differential device 1 described above will be described.

As shown in fig. 1,

annular oil reservoirs

13L, 13R are formed in the transmission case 2 at locations on the left and right sides thereof across the differential device 1, at locations defined by the left and right oil seals 12, the left and right bearings 6, the left and right inner portions 3a of the differential case 3, and the left and

right axles

4L, 4R, respectively, and plate-like guide members 15 are provided on the left and right sides in the transmission case 2 in a state of being attached to the left and right bearings 6, the guide members 15 guiding the lubricating oil lifted up by the rotating final gear 7 to the left and

right oil reservoirs

13L, 13R, respectively, as indicated by arrows in fig. 1.

As shown in fig. 3 and 4, cut-out oil grooves 3b are formed in two opposing portions of the end surfaces of the left and right inner portions 3a of the differential case 3, and these oil grooves 3b open to left and

right oil reservoirs

13L, 13R formed in the transmission case 2.

Further, as shown in fig. 1 and 2, circular hole-shaped

lubricating oil passages

16L, 16R are formed along the axial direction at the axial centers of the inner ends of the left and

right axle shafts

4L, 4R, respectively, and the two lubricating

oil passages

16L, 16R communicate with each other, specifically, as shown in fig. 2 and 3, the left and right lubricating

oil passages

16L, 16R communicate with each other through a sleeve 17 that penetrates the pinion shaft 9 in the axial perpendicular direction (the left and right direction in fig. 2 and 3) and left and right connecting pipes 18 that connect both ends of the sleeve 17 with the left and right lubricating

oil passages

16L, 16R.

Further, at two axially separated portions of the inner end portions of the left and

right axles

4L, 4R,

first oil passages

19L, 19R and

second oil passages

20L, 20R in the radial direction, which cross each of the lubricating

oil passages

16L, 16R, are formed, in other words, 4

first oil passages

19L, 19R and

second oil passages

20L, 20R are formed radially outward from the respective left and right lubricating

oil passages

16L, 16R.

The 4-

th oil passages

19L, 19R and the 2

nd oil passages

20L, 20R are formed at equal angular intervals (90 ° intervals) in the circumferential direction at the inner ends of the left and

right axles

4L, 4R, and the 4-

th oil passages

19L, 19R are selectively opened to oil grooves 3b (see fig. 4) formed in the end surfaces of the left and right inner portions 3a of the differential case 3, as shown in fig. 1 and 3 (only the left 1 st oil passage 19L is shown in fig. 3), and the 2 nd oil passages 20L are selectively opened to oil passages 21 between the back surfaces of the left and right side gears 11 and the inner surface of the differential case 3, as shown in fig. 1 to 3 (only the left 2 nd oil passage 20L is shown in fig. 3).

Next, an operation of the differential device 1 having the above-described lubricating structure will be described.

When rotational power output from a drive source such as an engine of a vehicle is input to the differential case 3 of the differential device 1 via the final gear 7, the differential case 3 rotates about the 1 st shaft center C1 in the transmission case 2. Further, a lubricating oil is stored in the bottom portion in the transmission case 2 in an amount to impregnate the final gear 7.

Further, when the vehicle travels straight, since the left and right drive wheels receive equal resistance from the road surface, the left and right pinion gears 10 revolve together with the differential case 3, the rotational power is transmitted to the left and right pair of side gears 11, and the left and

right axles

4L, 4R rotating together with the left and right side gears 11 and the left and right drive wheels are respectively driven to rotate, and at this time, the pair of pinion gears 10 do not rotate (rotate).

On the other hand, during turning of the vehicle, since a difference occurs in the resistance received by the left and right drive wheels from the road surface (a difference occurs in the moving distance of the left and right drive wheels), the pair of pinion gears 10 rotate on their axes, and the rotational speed of one side gear 11 is higher than that of the other side gear 11, so that the rotational power is appropriately distributed to the left and right drive wheels while the vehicle smoothly turns.

As described above, when the differential device 1 is operated and the final gear 7 rotates together with the differential case 3, the final gear 7 kicks up the lubricating oil stored in the bottom portion of the transmission case 2, and then, the kicked-up lubricating oil drops down as indicated by arrows in fig. 1 after hitting against the inner wall of the transmission case 2, and is efficiently guided to and collected in the left and

right oil reservoirs

13L, 13R along the left and right guide members 15.

Part of the lubricating oil introduced into the left and

right oil reservoirs

13L, 13R in the transmission 2 is introduced into the helical grooves 5 formed in the inner peripheral surface of the left and right inner portions 3a of the differential case 3 from the oil grooves 3b (see fig. 4) formed in the end surfaces of the left and right inner portions 3a of the differential case 3, and the other part of the lubricating oil is introduced into the 4-

th oil passages

19L, 19R formed in the inner end portions of the left and

right axle shafts

4L, 4R, respectively, so that part of the lubricating oil introduced into the helical grooves 5 formed in the inner peripheral surface of the inner portion 3a of the differential case 3 flows in the axial direction along the helical grooves 5 by the rotation of the left and

right axle shafts

4L, 4R, respectively, as indicated by arrows in fig. 1 and 3 (only one of which is shown in fig. 3), and passes through the oil passages 21 formed between the back surfaces of the left and right side gears 11 and the inner surface of the differential case 3, to.

Further, the other part of the lubricating oil introduced into the 1

st oil passages

19L, 19R formed at the inner ends of the left and

right axle shafts

4L, 4R flows from the 1

st oil passages

19L, 19R to the lubricating

oil passages

16L, 16R and is introduced into the 2

nd oil passages

20L, 20R, respectively, and then the lubricating oil introduced into the 2

nd oil passages

20L, 20R flows radially outward at the 2

nd oil passages

20L, 20R by the centrifugal force generated by the rotation of the

axle shafts

4L, 4R, and passes through the oil passage 21 between the back surfaces of the left and right side gears 11 and the inner surface of the differential case 3, so that each part is lubricated.

As described above, in the present embodiment, since the

lubricant oil passages

16L and 16R formed in the inner end portions of the left and

right axles

4L and 4R are communicated with each other, when the left and right supply amounts of the lubricant oil lifted up by the final drive gear 7 in the transmission case 2 are unbalanced, the lubricant oil on the side with the larger supply amount is supplied to the side with the smaller supply amount, and the supply amounts of the lubricant oil can be balanced left and right.

For example, as shown in fig. 1, when the amount of lubricant supplied is large on the right side and small on the left side, the excess lubricant on the right side is supplied to the left side via the

lubricant passages

16L, 16R communicating with each other, so the amount of lubricant supplied is balanced in the left-right direction, and the problem of seizure or wear of the left pinion gear 10 or the side gear 11 due to the insufficient amount of lubricant on the left side in the differential case 3 is solved.

Conversely, when the amount of lubricant supplied is large on the left side and small on the right side, the excess lubricant on the left side is supplied to the right side via the

lubricant passages

16L, 16R communicating with each other, so the amount of lubricant supplied is balanced in the left-right direction, and the problem of seizure or wear of the pinion gear 10 or the side gear 11 on the right side due to the insufficient amount of lubricant on the right side in the differential case 3 is eliminated.

< embodiment 2>

Next, embodiment 2 of the present invention will be described with reference to fig. 7 to 10.

Fig. 7 is a longitudinal sectional view of a differential device having a lubricating structure according to embodiment 2 of the present invention, fig. 8 is an enlarged detail view of a portion C of fig. 7, fig. 9 is a longitudinal sectional view of a main portion of the differential device, and fig. 10 is a perspective view of a screw shaft of the differential device. In these drawings, the same elements as those shown in fig. 1 to 6 are denoted by the same reference numerals, and a re-description thereof will be omitted below.

In the present embodiment, as shown in fig. 7 and 8, the screw shafts 22 shown in fig. 10 are fitted into the lubricating

oil passages

16L, 16R formed at the inner ends of the left and

right axles

4L, 4R, respectively, and the screw shafts 22 are rotated together with the

axles

4L, 4R for flowing lubricating oil toward the inner end surfaces of the

axles

4L, 4R, and the other configuration is the same as that of embodiment 1, here, as shown in detail in fig. 8, the left and right screw shafts 22 are fixed by fitting the connecting pipes 23 connected to the inner ends thereof into the inner ends of the lubricating

oil passages

16L, 16R fitted to the left and

right axles

4L, 4R, respectively, and are rotated together with the left and right

rotating shafts

4L, 4R.

In the lubricating structure of the present embodiment as well, similarly to the lubricating structure of embodiment 1, the lubricating oil is equally supplied to the left and right sides in the differential case 3, and an effect of preventing the pinion 10 and the side gear 11 from being burned or worn is obtained, but the lubricating oil is forcibly vigorously made to flow in the lubricating

oil passages

16L, 16R as shown by arrows in fig. 9 (only one is shown in fig. 9) by rotating the left and right screw shafts 22 together with the left and

right axles

4L, 4R, and is thereby lubricated in each part, and an effect of improving the lubricating effect of the lubricating oil is obtained.

In the above embodiment, the spiral grooves 5 are formed in the inner peripheral surfaces of the left and right inner portions 3a of the differential case 3, respectively, but the spiral grooves may be formed in the outer peripheral surfaces of the inner end portions of the left and

right axle shafts

4L, 4R.

The application of the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical ideas described in the claims, the specification, and the drawings.

Claims

1. A lubricating structure for a differential device, wherein respective end portions of left and right axles are rotatably inserted and supported in respective left and right inner side portions of a differential case rotatably supported in a transmission case, lubricating oil stored in a bottom portion of the transmission case is raised by rotation of a final gear attached to the differential case, and the raised lubricating oil is supplied into the differential case through a spiral groove formed in either one of inner peripheral surfaces of the left and right inner side portions of the differential case and an outer periphery of an inner end portion of the axle to lubricate each portion,

the lubricating structure of the differential device is characterized in that,

lubricating oil passages are formed in the axial direction at respective inner end portions of left and right inner portions of the left and right axles inserted and supported in the differential case, and the two lubricating oil passages communicate with each other,

the lubricating structure of the differential device is configured to supply a part of the lubricating oil kicked up by the final gear into the differential case via the lubricating oil passages communicating with each other.

2. The lubricating structure of a differential device according to claim 1,

an annular oil reservoir defined by an oil seal fitted to the inner peripheries of left and right opening portions of the transmission through which the left and right axles pass and a bearing rotatably supporting the differential case are formed on each of the left and right sides of the transmission,

the lubricating structure of the differential device is configured to introduce the lubricating oil raised by the main transmission gear into the left and right oil reservoirs, respectively.

3. The lubricating structure of a differential device according to claim 2,

and a guide member for guiding the lubricating oil raised by the main transmission gear to the left and right oil storage portions, respectively.

4. The lubricating structure of a differential device according to claim 2 or 3,

oil grooves communicating with the left and right oil reservoirs are formed in respective end surfaces of left and right inner portions of the differential case, and a 1 st oil passage communicating the lubricating oil passages formed in the respective end portions of the left and right axles with the oil grooves is formed in the respective end portions of the left and right axles.

5. The lubricating structure of a differential device according to claim 4,

radial 2 nd oil passages for supplying lubricating oil to the back surfaces of the left and right side gears coupled to the outer peripheries of the inner end portions are formed in the inner end portions of the left and right axles, respectively.

6. The lubricating structure of a differential device according to any one of claims 1 through 5,

screw shafts are fitted into the respective lubricant passages formed in the respective inner end portions of the left and right axles, and the screw shafts rotate together with the respective axles to flow lubricant to the inner end surfaces of the axles.