FR3062160A1 - OIL PAN - Google Patents

Abstract

A first portion of oil strainer (34) formed integrally with a first oil sump portion (31) is formed in the first oil sump portion (31) having a shallow depth. A second portion of oil strainer (35) extending from a rear end of the first portion of oil strainer (34) to a bottom wall (32A) of a second oil sump portion (32) is disposed in the second oil sump portion (32) having a great depth. A second portion of oil strainer (35) on which a distal end of the second portion of oil strainer (35) is fitted is formed at the rear end of the first portion of oil strainer (34). ), and the second oil strainer portion (35) is formed in a position connected from the lower wall (31A) of the first oil sump portion (31) to a curved portion (33).

Description

® Agent (s): CABINET PLASSERAUD.

FR 3 062 160 - A1 ® OIL PAN.

(57) A first portion of oil strainer (34), formed integrally with a first portion of oil pan (31), is formed in the first portion of oil pan (31) having a shallow depth. A second portion of oil strainer (35) extending from a rear end of the first portion of oil strainer (34) to a bottom wall (32A) of a second portion of oil pan (32) is arranged in the second oil pan portion (32) having a great depth. A second portion of oil strainer (35) to which a distal end of the second portion of oil strainer (35) is fitted is formed at the rear end of the first portion of oil strainer (34 ), and the second portion of oil strainer (35) is formed in a position connected from the bottom wall (31 A) of the first portion of oil pan (31) to a curved portion (33).

OIL PAN

The present invention relates to an oil pan installed in a vehicle.

An oil pan which stores oil intended to lubricate an internal combustion engine installed in a vehicle is arranged under the internal combustion engine, and an oil strainer intended to remove a foreign substance from the oil sucked in. an oil pump is arranged in the oil pan. For example, Japanese Examined Utility Model Registration Publication No. 62-24730 describes an oil pan known as a conventional oil pan with an oil strainer.

This oil pan has two-level lower faces, high and low, having different heights with a plate interposed between them, and the lower face on a high level side having a shallow depth and the lower face on the side of low level having great depth are connected through a curved portion. The oil strainer is integrally formed with the bottom surface on the low level side.

A transmission is connected to an internal combustion engine including such an oil pan, and the transmission vibrates in the vertical and left-right directions due to the vibration of the internal combustion engine, the vibration of the vehicle, etc. In this way, the vibration of the transmission is transmitted to the oil pan.

In the conventional oil pan, the bottom surface on the high level side and the bottom surface on the low level side are connected through the curved portion, and a portion of the oil pan having the bottom surface on the low level side (hereinafter called the oil pan portion on the low level side) has less rigidity than a portion of the oil pan having the lower surface on the high level side (hereinafter called high level side oil pan portion).

For this reason, when the transmission is connected to the high level side oil pan portion, the low level side oil pan portion is easily deformed using the curved portion as a starting point due to vibration. of the transmission. Since the oil strainer is arranged in one piece in the oil sump portion on the low level side, when the oil sump portion on the low level deforms, the oil stored in the portion oil sump on the low level side stirs considerably. For this reason there is the concern that the oil screen can suck in air, and the oil pump can suck in air.

This invention was designed in view of the aforementioned problems, and an object of this invention is to produce an oil pan capable of suppressing deformation through the increase in rigidity.

According to aspects of this invention is produced an oil pan disposed in an internal combustion engine comprising a cylinder block, the internal combustion engine being installed in a vehicle such that a central axis of rotation of a crankshaft is directed in a front-rear direction of the vehicle, the oil sump being connected to a lower part of the cylinder block and to a transmission disposed behind the internal combustion engine, the oil sump including a first portion of sump d oil, a second portion of the oil pan located behind the first portion of the oil pan and connected to the transmission, the second portion of the oil pan having a bottom wall located under a bottom wall of the first portion of the pan of oil to have a depth greater than a depth of the first portion of the oil pan, and a curved portion which is curved from the bottom wall of the first portion of the oil pan oil to the bottom wall of the second portion of the oil pan, wherein a first portion of the oil strainer extending in a direction of the central axis of rotation of the crankshaft along the bottom wall of the first portion of oil pan from a front wall of the first portion of oil pan is formed in the first portion of oil pan, the first portion of oil strainer being formed integrally with the first portion of oil pan, a second portion of oil strainer extending from a rear end of the first portion of oil strainer to the bottom wall of the second portion of oil pan is disposed in the second portion of casing of oil, a boss portion is formed at the rear end of the first oil strainer portion, a distal end of the second oil strainer portion fitting over the boss portion, and the boss portion is formed at least ins in a position in which the bottom wall of the first oil pan portion is connected to the curved portion.

As described above, according to this invention, it is possible to suppress the deformation of the oil pan thanks to the increase in the rigidity of the latter.

Fig. 1 is a plan view of a vehicle including an oil pan according to an embodiment of this invention;

Fig. 2 is a bottom view of the vehicle including an oil pan according to an embodiment of this invention;

Fig. 3 is a side view of a power unit seen from a direction of an arrow ΙΠ in FIG. 1;

Fig. 4 is a front view of an engine including an oil pan according to an embodiment of this invention;

Fig. 5 is a top view of an oil pan according to an embodiment of this invention;

Fig. 6 is a cross-sectional view taken in a direction of the arrows VI-VI of FIG. 5;

Fig. 7 is a cross-sectional view taken in a direction of the arrows VII-VII of FIG. 5;

Fig. 8 is a top view of an oil pan including a second portion of oil strainer having another shape according to an embodiment of this invention; and Fig. 9 is a cross-sectional view taken in a direction of the arrows IX-IX of FIG. 8.

An oil pan according to embodiments of this invention is an oil pan disposed in an internal combustion engine comprising a main unit, the internal combustion engine being installed in a vehicle such that a central axis of rotation of a crankshaft is directed in a front-rear direction of the vehicle, the oil sump being connected to a lower part of the cylinder blocks and to a transmission disposed behind the internal combustion engine, the oil sump including a first portion of oil pan, a second portion of oil pan located behind the first portion of oil pan and connected to the transmission, the second portion of oil pan having a bottom wall located under a bottom wall of the first portion oil pan to have a depth greater than a depth of the first oil pan portion, and a curved portion which is curved from the bottom wall of the first p proportion of oil pan to the bottom wall of the second portion of oil pan, wherein a first portion of oil strainer extending in a direction of the central axis of rotation of the crankshaft along the wall bottom of the first oil pan portion from a front wall of the first oil pan portion is formed in the first oil pan portion, the first oil strainer portion being formed in one piece with the first portion of the oil pan, a second portion of the oil strainer extending from a rear end of the first portion of the oil strainer to the bottom wall of the second portion of the oil pan is disposed in the second portion of the oil pan, a boss portion is formed at the rear end of the first portion of the oil strainer, a distal end of the second portion of the oil strainer fitting over the portion of boss, and the boss portion age is formed at least in one position in which the bottom wall of the first oil pan portion is connected to the curved portion.

In this way, it is possible to suppress the deformation of the oil sump by increasing the rigidity of the oil sump.

In the following, embodiments of an oil pan according to this invention will be described with reference to the drawings.

Figs. 1 to Fig. 9 are diagrams, which each illustrate an oil pan of an embodiment according to this invention. In Figs. 1 to Fig. 9, a vertical direction, a front-rear direction and a left-right direction are directions seen from a driver in a vehicle.

A constitution will first be described.

In Fig. 1 and FIG. 2, a vehicle 1 includes an engine 2 such as an internal combustion engine. In Fig. 3 and FIG. 4, the engine 2 includes a cylinder block 3, a cylinder head 4 connected to an upper part of the cylinder block 3, and an oil pan 5 connected to a lower part of the cylinder block 3.

One (or more) cylinder (s) (not shown) is (are) formed in the cylinder block 3, and a piston (not shown) is disposed reciprocally in each cylinder. A crankshaft 3A (see Fig. 4) is arranged in rotation in the cylinder block 3, and a reciprocating movement of the piston is converted into a rotary movement of the crankshaft 3A. Fig. 3 illustrates a central axis of rotation 3a of the crankshaft 3A.

An intake / exhaust valve (not shown) for opening and closing an intake / exhaust camshaft (not shown) and an intake / exhaust port (not shown) are disposed in the cylinder head 4. The cylinder head 4 introduces air into the cylinder through the intake port, and emits exhaust gases from the cylinder through the exhaust port ¹ . The oil pan 5 stores oil intended to lubricate a lubrication part of the crankshaft, of the piston, etc.

The engine 2 is installed so that the central axis of rotation 3a of the crankshaft 3A is directed in the front-rear direction of the vehicle 1 (see Fig. 3), and the vehicle 1 of this embodiment comprises a longitudinal engine .

On the Lig. 1 and Lig. 2, a transmission 6 is connected to the engine 2, and the transmission 6 moves and outputs a speed of rotation of the crankshaft 3A. The transmission 6 is installed behind the engine 2, and the oil pan 5 is connected to the lower part of the cylinder block 3 and to the transmission 6 (see Fig. 3).

A front end of a first front drive shaft 7 is connected to the transmission 6, and the first front drive shaft 7 extends rearward in the front-rear direction of the vehicle 1 from the transmission 6. A device 8 is installed behind the transmission 6, and a rear end of the first front drive shaft 7 is connected to the transfer device 8. In this way, the power of the transmission 6 is transmitted to the transfer device 8 via the first front drive shaft 7.

A rear end of a second front drive shaft 9 and a front end of a rear drive shaft 10 are connected to the transfer device 8. The second front drive shaft 9 extends forward in the forward direction - rear of the vehicle 1 from the transfer device 8 to one side in a vehicle width direction of the engine 2.

One end having the second front drive shaft 9 is connected to a front differential device 11. The front differential device 11 transmits the power from the second front drive shaft 9 to the front wheels 13L and 13R through left drive shafts and straight 12L and 12R on the front side so that the front wheels are allowed to rotate differently.

A rear end of the rear drive shaft 10 is connected to a rear differential device (not shown). The rear differential device transmits power from the rear drive shaft 10 to the rear wheels (not shown) through left and right drive shafts on the rear side (not shown) such that the rear wheels are allowed to rotate differently.

The transfer device 8 switches a transmission path to transmit the power transmitted from the first front drive shaft 7 to one or both of the second front drive shaft 9 and the rear drive shaft 10.

In this way, a part-time “4 Wheel Drive” (or four-wheel drive also abbreviated 4WD) which is activated to be switched to two-wheel drive or four-wheel drive is implemented in the vehicle 1. The transfer device 8 can be driven to have a power transmission path that constantly drives vehicle 1 using four wheels, i.e., be a full-time 4WD.

The first front drive shaft 7 of this embodiment corresponds to a first drive shaft of this invention and the second front drive shaft 9 corresponds to a second drive shaft of this invention. The front differential device 11 corresponds to a differential device of this invention.

On the Lig. 5 and Lig. 6, the oil pan 5 includes a first portion of the oil pan 31 and a second portion of the oil pan 32 having lower walls 31A and 32A of different heights, and the second portion of the oil pan 32 located behind the first oil pan portion 31 so that the second oil pan portion 32 is connected to the transmission 6. The first oil pan portion 31 includes the bottom wall 31 A, a front wall 31B and side walls 31C and 31D.

The second oil pan portion 32 includes the bottom wall 32A, a rear wall 32B and side walls 32C and 32D. The bottom wall 32A is located at a level below a level at which the bottom wall 31 A is located, and the second oil pan portion 32 is formed to have a greater depth than that of the first oil pan portion. oil 31. The rear wall 32B is connected to the transmission 6 by a bolt 38 (see Fig. 3).

The side walls 31C and 31D are provided in one piece with the side walls 32C and 32D, and the side walls 31C, 31D, 32C and 32D correspond to a side wall of the oil pan 5. In the oil pan 5 , oil is stored in a space surrounded by the bottom walls 31A and 32A, the front wall 31B, the rear wall 32B and the side walls 31C, 31D, 32C and 32D.

The oil pan 5 has a curved portion 33. The curved portion 33 is curved from the bottom wall 31A of the first oil pan portion 31 to the bottom wall 32A of the second oil pan portion 32. Here , the curved portion 33 can extend from the bottom wall 31A of the first oil pan portion 31 to the bottom wall 32A of the second oil pan portion 32.

In the oil pan 5 of this embodiment, the curved portion 33 can be formed between the bottom wall 31A of the first oil pan portion 31 and the bottom wall 32A of the second oil pan portion 32 The Lig. 5 illustrates areas in which the first oil pan portion 31, the second oil pan portion 32 and the curved portion 33 are formed.

A first portion of oil strainer 34 is formed in the first portion of oil pan 31. The first portion of oil strainer 34 extends from the front wall 31B of the first portion of oil pan 31 the along the bottom wall 31A in a direction of the central axis of rotation 3a of the crankshaft, and is formed integrally with the first portion of the oil pan 31. An oil passage 34a through which s the oil is formed inside the first portion of the oil strainer 34.

A second portion of oil strainer 35 is disposed in the second portion of oil pan 32. The second portion of oil strainer 35 extends from a rear end of the first portion of oil strainer 34 along from the curved portion 33 to the bottom wall 32A of the second oil pan portion 32. An oil passage 35a through which the oil flows is formed inside the second strainer portion. oil 35, and the oil passage 35a communicates with the oil passage 34a.

A foreign substance capture portion (not shown) is disposed at a rear end of the second oil strainer portion 35 facing the bottom wall 32A of the second oil pan portion 32. A distal end of the first portion of oil strainer 34 is connected to an oil filter 41 (see Fig. 4), and the oil filter 41 is connected to an oil pump 42 (see Fig. 4) by means of a pipe oil (not shown).

The oil pump 42 is rotated by the crankshaft 3A. When the oil pump 42 is rotated, the oil in the oil pan 5 is drawn from the rear end of the second portion of the oil strainer 35.

The oil drawn in by the second portion of oil strainer 35 flows through the oil passage 34a of the first portion of oil strainer 34 after a foreign substance has been removed from the oil by the portion of foreign substance capture and the oil flows through the oil passage 35a.

The oil flowing through the oil passage 35a is introduced into the oil filter 41, purified by the oil filter 41, then supplied from the oil pump 42 to a lubrication part of the engine 2. From this way, the lubrication part is lubricated by the purification oil.

A boss portion 31E is formed at the rear end of the first oil strainer portion 34, and a distal end of the second oil strainer portion 35 is fitted to the boss portion 31E. The boss portion 31E is formed in a position where the bottom wall 31A of the first oil pan portion 31 is connected to the curved portion 33.

In Fig. 5, a flange 35A is formed at the distal end of the first portion of oil strainer 34. A screw groove 31e to which the bolt 38 is fixed is formed in the boss portion 31E, and the flange 35A is fixed to the boss portion 31E by the bolt 38. In this way, the distal end of the second oil strainer portion 35 is fixed to the boss portion 31E. The screw groove 31e of this embodiment corresponds to a fixing portion of this invention.

The boss portion 31E is formed in a shape in which a dimension L2 in a direction orthogonal to an axial direction of the first oil strainer portion 34 (the same direction as a direction of the central axis of rotation 3a) is greater than a dimension L1 in the axial direction of the first portion of oil strainer 34.

A swelling portion 31F is formed on the bottom wall 31A of the first oil pan portion 31. The swelling portion 31F swells upward from the bottom wall 31A (see Fig. 7). The swelling portion 31F swells upward from the bottom wall 31A on a side at which the front differential device 11 is installed relative to the first portion of the oil strainer 34.

The inflation portion 31F connects the side wall 31C of the first oil pan portion 31 facing the front differential device 11, the first oil strainer portion 34, the boss portion 31E and the curved portion 33.

Engine 2, transmission 6, first front drive shaft 7, transfer device 8, second front drive shaft 9, rear drive shaft 10, front differential device 11 and drive shafts 12L and 12R of this embodiment are included in a powertrain which transmits the power generated in the engine 2 to the front wheels 13L and 13R. In addition, the motor 2 and the transmission 6 of this embodiment are included in the power unit which generates the power.

An operation will then be described.

During the operation of the engine 2, the transmission 6 vibrates in the vertical direction X and in the. left-right direction Y due to engine vibration 2, vehicle vibration 1, etc. (see Fig. 4). Since the oil pan 5 has the second oil pan portion 32 deeper than the first oil pan portion 31, the rigidity of the second oil pan portion 32 is lower than that of the first portion of the oil pan 31. In addition, in the oil pan 5, the second portion of the oil pan 32 is connected to the transmission 6.

In this way, when the vibration of the transmission 6 is transmitted to the oil pan 5, the oil pan 5 is caused to deform in the front-rear direction R (see Fig. 3) of the vehicle 1 using the curved portion 33 as a starting point.

The oil pan 5 of this embodiment includes the first oil pan portion 31, the second oil pan portion 32 which is located behind the first oil pan portion 31 and is connected to the transmission 6 and includes the bottom wall 32A situated under the bottom wall 31A of the first portion of the oil pan 31 so that the second portion of the oil pan 32 is deeper than the first portion of the oil pan 31, and the curved portion which is curved from the bottom wall 31A of the first oil pan portion 31 to the bottom wall 32A of the second oil pan portion 32.

The first portion of oil strainer 34, which is integrally formed with the first portion of oil pan 31 to extend from the front wall 31B of the first portion of oil pan 31 along the bottom wall 31A of the first portion of the oil pan 31 in the direction of the central axis of rotation 3a of the crankshaft 3A is formed in the first portion of the oil pan 31.

The second portion of oil strainer 35 extending from the rear end of the first portion of oil strainer 34 to the bottom wall 32A of the second portion of oil pan 32 is disposed in the second portion of casing oil 32.

The boss portion 31E to which the distal end of the second oil strainer portion 35 is fitted is formed at the rear end of the first oil strainer portion 34, and the boss portion 31E is formed on a position in which the bottom wall 31A of the first oil pan portion 31 is connected to the curved portion 33.

In this way, it is possible to increase the rigidity of the first portion of oil pan 31 by using the first portion of oil strainer 34, and to increase the rigidity of the curved portion 33 by using the portion of boss 31E. For this reason, it is possible to prevent the second oil pan portion 32 from deforming from the curved portion 33 as a starting point due to the vibration of the transmission 6.

Since the deformation of the second oil pan portion 32 having a great depth can be suppressed in this way, it is possible to prevent the oil from stirring considerably in the second oil pan portion 32 in which more oil is stored than in the first portion of the oil pan 31.

For this reason, it is possible to prevent the second portion of oil strainer 35 from drawing air into the second portion of oil pan 32, and to prevent the suction of air from the pump to 42 oil to occur.

In addition, since the second portion of the oil pan 32 is located behind the first portion of the oil pan 31, when the traveling wind B hits the oil pan 5 from the front of the vehicle 1, the displacement wind B strikes the curved portion 33 along the bottom wall 31A of the first oil pan portion 3, then flows backwards along the bottom wall 32A from the curved portion 33 (see Fig 3).

In this way, it is possible to cool the oil stored in the oil pan 5 using the displacement wind and to maintain the oil at an appropriate temperature. For this reason, it is possible to maintain an appropriate viscosity of the oil, and to prevent an engine part from deteriorating at an early stage thanks to the improvement of the lubricating power of the lubricating part of the engine 2.

In addition, according to the oil pan 5 of this embodiment, the boss portion 31E is formed according to the shape in which the dimension L2 in the direction orthogonal to the axial direction of the first portion of oil strainer 34 is greater than the dimension L1 in the axial direction of the first portion of oil strainer 34.

In addition to this, the boss portion 31E has the screw grooves 31e, 31e. The distal end of the second portion of oil strainer 35 is fixed to the boss portion 31E by screwing the bolts 38, 38 into the screw grooves 31e, 31e.

In this way, an installation area of the boss portion 31E relative to the curved portion 33 can be increased and a thickness of the boss portion 31E in a direction of the screw groove 31e can be increased by a depth of the screw groove 31e. For this reason, it is possible to more effectively improve the rigidity of the curved portion 33, and more effectively prevent the second oil pan portion 32 from deforming by using the curved portion 33 as a starting point due the vibration of the transmission 6.

At the same time, the powertrain of this embodiment is installed behind the transmission 6 and includes the transfer device 8 connected to the transmission 6 via the first front drive shaft 7 and the second front drive shaft 9 s' extending in the front-rear direction of the vehicle 1 from the transfer device 8 to the side of the engine 2.

In addition, the powertrain is disposed at the front end of the second front drive shaft 9 and includes the front differential device 11 which transmits power from the second front drive shaft 9 to the front wheels 13L and 13R so that the wheels before 13L and 13R are allowed to rotate differently.

In this way, when the transmission 6 vibrates in the vertical and left-right directions, the first front drive shaft 7 vibrates in the front-rear direction of the vehicle 1, and this vibration is transmitted to the front differential device 11 through the transmission device. transfer 8 and the second front drive shaft 5 9.

Since the second front drive shaft 9 and the front differential device 11 are installed to be laterally offset from the oil pan 5, it is likely that the oil pan 5 will deform to a side at which the second front drive shaft 9 and the front differential device 11 10 are installed (a direction XI in FIG. 1).

According to the oil pan 5 of this embodiment, the swelling portion 31F is formed on the bottom wall 31A of the first oil pan portion. The swelling portion 31F swells upward from the bottom wall 31A on the side at which the front differential device 11 is installed relative to the first portion of oil strainer 34.

In addition to this, the inflation portion 31F connects the side wall 31C of the first oil pan portion 31 facing the front differential device 11, the first oil strainer portion 34, the boss portion 31E and the curved portion 33.

In this way, it is possible to increase the rigidity of the first portion of the oil pan 31, and to easily prevent the oil pan 5 from deforming towards the side of the front differential device. For this reason, it is possible to more effectively prevent the second oil pan portion 32 from deforming by using the curved portion 33 as a starting point due to the vibration of the transmission 6.

In addition, in the oil pan 5 of this embodiment, as illustrated in FIG. 8 and FIG. 9, a rib 35B can be arranged in the second portion of oil strainer 35, a boss portion 33A in which screw grooves are formed can be disposed in the curved portion 33, and the rib 35B 30 can be fixed to the boss portion 33A using bolts 43. The boss portion 31E of this embodiment corresponds to a first boss portion of this invention, and the boss portion 33A corresponds to a second boss portion of this invention .

In this way, it is possible to connect the second portion of oil strainer to the curved portion 33, and to more effectively increase the rigidity of the curved portion 33. For this reason, it is possible to more effectively prevent the second portion of oil pan 32 to deform using the curved portion 5 33 as a starting point due to the vibration of the transmission.

Although embodiments of this invention have been described, it is obvious that those skilled in the art will be able to make changes without departing from the scope of this invention. It is understood that all these modifications and equivalences are implied in the appended claims.

Claims (5)

1. Oil pan (5) arranged in an internal combustion engine (2) comprising a cylinder block (3), the internal combustion engine (2) being installed in a vehicle (1) so that a central axis of rotation (3a) of a crankshaft (3A) is directed in a front-rear direction of the vehicle (1), the oil sump (5) being connected to a lower part of the cylinder block (3) and to a transmission (6) arranged behind the internal combustion engine (2), the oil pan (5) comprising: a first portion of oil pan (31); a second portion of oil pan (32) located behind the first portion of oil pan (31) and connected to the transmission (6), the second portion of oil pan (32) having a bottom wall (32A ) located under a bottom wall (31 A) of the first portion of the oil pan (31) to have a greater depth than a depth of the first portion of the oil pan (31); and a curved portion (33) curved from the bottom wall (31 A) of the first oil pan portion (31) to the bottom wall (32A) of the second oil pan portion (32), wherein a first portion of oil strainer (34) extending in a direction of the central axis of rotation (3a) of the crankshaft (3A) along the bottom wall (31 A) of the first portion of the crankcase oil (31) from a front wall (31B) of the first portion of the oil pan (31) is formed in the first portion of the oil pan (31), the first portion of the oil strainer (34) being formed integrally with the first oil pan portion (31), a second oil strainer portion (35) extending from a rear end of the first oil strainer portion (34) toward the bottom wall (32A) of the second oil pan portion (32) is disposed in the second oil pan portion (32), a boss portion (31E) is formed at the rear end of the first oil strainer portion (34), a distal end of the second oil strainer portion (35) fitting over the second oil strainer portion (35), and the second portion of oil strainer (35) is formed at least in one position in which the bottom wall (31 A) of the first portion of oil pan (31) is connected to the curved portion (33). 2. Oil pan (5) according to claim 1, wherein the second portion of oil strainer (35) is formed in a shape, a dimension in a direction orthogonal to an axial direction of the first portion of strainer d the oil (34) is larger than a dimension in the axial direction of the first portion of oil strainer (34) depending on the shape, and the first portion of oil strainer (34) has a fixing portion, the distal end of the second portion of oil strainer (35) being attached to the attachment portion. 3. Oil pan (5) according to claim 1 or 2, wherein the vehicle (1) includes a transfer device (8) installed behind the transmission (6) and connected to the transmission (6) through 'a first drive shaft (7), a second drive shaft (9) extending in the front-rear direction of the vehicle (1) from the transfer device (8) to one side of the internal combustion engine (2 ), and a differential device (11) arranged at a front end of the second drive shaft (9) for transmitting power to the second drive shaft (9) to the front left and right wheels so that the front wheels left and right are allowed to rotate differently, the oil pan (5) has an inflation portion (31F) inflating upward from at least one bottom wall on one side at which the second drive shaft (9 ) or the differential device (11) is installed relative to the prem 1st oil strainer portion (34), and the inflation portion (31F) connects a side wall of the oil pan (5) facing the second transmission shaft (9) or the differential device (11), the first portion of oil strainer (34), the second portion of oil strainer (35) and the curved portion (33). 4. Oil pan (5) according to any one of claims 1 to 3, in which the second portion of oil strainer (35) extends along the curved portion (33), and 5 when the second portion of oil strainer (35) is placed on a first boss portion (31E), a second boss portion (3 3 A) is formed in the curved portion (33), the second portion of strainer oil (35) being attached to the second boss portion (33A).