Oil pan structure and separator for partitioning oil pan

An oil pan 1 includes: an oil pan body 2 having a reservoir 21 for storing oil circulated in an engine E and returned to the reservoir 21; and a separator 3 having a vertically extending sidewall unit 4 partitioning the reservoir 21 into a first reservoir 21a for storing high-temperature oil and a second reservoir 21b for storing low-temperature oil. The first reservoir 21a has a suction-member-placement region 22 in which a member for sucking oil is provided. The separator 3 has an inclined portion 61 extending, to the suction-member-placement region 22, from a portion below a downstream end of a return pipe Rt for allowing oil to return to the first reservoir 21a.

BACKGROUND

The present disclosure relates to oil pan structures for storing oil circulated in power units in, for example, automobiles, and also relates to separators for partitioning oil pans.

Conventional power units include oil pans for storing oil in order to lubricate or cool parts of the power units. Oil stored in the oil pan is sucked by an oil pump through a strainer, circulates in parts of the power unit, and then returns to the oil pan.

Immediately after a cold start of a power unit, oil stored in an oil pan is cold, and therefore, has high viscosity, thereby reducing fuel efficiency. To prevent this, an oil pan described in Japanese Patent Publication No. 2008-297972 (hereinafter referred to as Patent Document 1) includes: an oil pan body having a reservoir for storing oil; and a separator disposed in the oil pan body. The separator partitions the reservoir into a first reservoir located inside the separator and a second reservoir located outside the separator. Immediately after a cold start, oil in the first reservoir is supplied to parts of a power unit through a strainer disposed in a lower portion of the first reservoir, circulates in the parts of the power unit, and then returns to the first reservoir. In this manner, oil in the first reservoir is continuously supplied to the parts of the power unit, thereby quickly increasing the temperature of oil circulating in the parts of the power unit.

SUMMARY

Immediately after a cold start of a power unit, the temperature of oil is low, and the viscosity of the oil is high. Accordingly, the power unit exhibits poor lubrication performance. In the oil pan of Patent Document 1, however, oil warmed after having circulated in the power unit returns to the reservoir from various portions of the oil pan body located above the reservoir. Before returning to the reservoir, the oil comes into contact with various portions of the separator. Accordingly, the area of oil in contact with the separator per a unit amount of oil is large, and thus oil warmed in the power unit is cooled before the oil reaches the strainer. Consequently, it takes time to start a continuous supply of oil with high lubrication performance to the power unit.

It is therefore an object of the present disclosure to provide an oil pan structure capable of continuously supplying oil with high lubrication performance to a power unit by reducing the contact area of oil returned from the power unit with a separator per a unit amount of oil. It is another object of the present disclosure to provide a separator for partitioning an oil pan.

SOLUTION TO THE PROBLEM

To achieve the above-mentioned object, in a first aspect of the present invention, an oil pan structure includes: an oil pan body including a reservoir configured to store oil circulated in a power unit and returned to the reservoir; and a separator including a vertically extending sidewall unit configured to partition the reservoir into a first reservoir and a second reservoir. In the oil pan structure, oil is allowed to flow between the first reservoir and the second reservoir, the first reservoir has a suction-member-placement region in which a member for sucking oil is provided, and the separator has an oil guide surface extending, to the suction-member-placement region, from a portion below a downstream end of an oil passageway configured to allow oil circulated in the power unit to return to the first reservoir.

In a second aspect of the present invention, in the oil pan structure of the first aspect, an oil receiver configured to receive oil below the downstream end of the oil passageway is provided on the oil guide surface, and the oil receiver is located on top of the oil guide surface.

In a third aspect of the present invention, the oil pan structure of the first or second aspect further includes: a communication portion configured to establish communication between the first reservoir and the second reservoir; and an opening/closing means configured to open the communication portion when a temperature of oil in the first reservoir is equal to or higher than a given temperature, and to close the communication portion when the temperature of oil in the first reservoir is lower than the given temperature.

In a fourth aspect of the present invention, in the oil pan structure of the first or second aspect, a strainer configured to filter oil to be supplied to the power unit is provided in the first reservoir, the strainer includes a first strainer portion and a second strainer portion, and the first strainer portion is formed as one piece with the separator.

In a fifth aspect of the present invention, in the oil pan structure of the fourth aspect, the separator includes a first separator portion and a second separator portion, the first strainer portion is formed as one piece with the first separator portion, and the second strainer portion is formed as one piece with the second separator portion.

In a sixth aspect of the present invention, in the oil pan structure of the first or second aspect, a straightening means configured to straighten a flow of oil is formed in an oil guide part, and the straightening means projects upward from the oil guide part, and extends along the oil guide part.

In a seventh aspect of the present invention, in the oil pan structure of the first or second aspect, the oil pan body includes a protrusion protruding toward the reservoir, the separator includes an interference prevention portion configured to prevent interference with the protrusion, and an oil guide surface is provided on a surface of the interference prevention portion toward the first reservoir.

In an eighth aspect of the present invention, a separator provided in an oil pan including a reservoir configured to store oil circulated in a power unit and returned to the reservoir, includes a vertically extending sidewall unit configured to partition the reservoir into a first reservoir and a second reservoir. The separator partitions an inside of the oil pan such that oil is allowed to flow between the first reservoir and the second reservoir. In the separator, the first reservoir includes a suction-member-placement region in which a member for sucking oil is provided, and the separator has an oil guide surface extending, to the suction-member-placement region, from a portion below a downstream end of an oil passageway configured to allow oil circulated in the power unit to return to the first reservoir.

ADVANTAGES OF THE INVENTION

In the first aspect, oil returned after having circulated in parts of the power unit, collected in the oil passageway, and dropped from the downstream end of the oil passageway, is guided to the suction-member-placement region along the oil guide surface. Accordingly, the contact area of oil returned from the power unit with the separator per a unit amount of oil can be reduced. Thus, oil warmed in the power unit can be guided to the suction-member-placement region while being kept warm. As a result, oil exhibiting low viscosity and high lubrication performance can be supplied to the power unit again even immediately after a cold start of the power unit, for example.

In the second aspect, since the oil receiver is located on top of the oil guide surface, the oil receiver can be located closer to the downstream end of the oil passageway, and thus oil dropped from the downstream end of the oil passageway can be received at a position closer to the oil passageway. Accordingly, it is possible to reduce mixture of air in oil during dropping of the oil, as much as possible. As a result, oil exhibiting high lubrication performance can be supplied to the power unit again.

In the third aspect, when the temperature of oil in the first reservoir is lower than a given temperature, the opening/closing means closes the communication portion to guide oil returned from the power unit to the first reservoir. On the other hand, when the temperature of oil in the first reservoir is equal to or higher than the given temperature, the opening/closing means opens the communication portion to guide oil returned from the power unit, from the communication portion to the second reservoir. In this manner, the temperature of oil in the first reservoir and the temperature of oil in the second reservoir can be adjusted.

In the fourth aspect, the first strainer portion is formed as one piece with the separator. Accordingly, in assembly of the first strainer portion and the second strainer portion, the relative positions of the strainer and the oil guide surface are less likely to be shifted. With this configuration, oil warmed after having circulated in parts of the power unit can always return to the same position in the oil suction port unit of the strainer. Thus, oil exhibiting high lubrication performance can be continuously supplied to the power unit. Moreover, the first strainer portion is fowled as one piece with the separator, and the second strainer portion is mounted to the first strainer portion. Thus, the strainer can be easily mounted to the separator, thereby reducing the number of processes of assembly.

In the fifth aspect, the first strainer portion is formed as one piece with the first separator portion of the separator, and the second strainer portion is formed as one piece with the second separator portion of the separator. Accordingly, when the first separator portion and the second separator portion are coupled together to form the separator, the relative positions of the strainer and the oil guide surface are less likely to be shifted. Thus, as in the fourth aspect, oil exhibiting high lubrication performance can be continuously supplied to the power unit. Further, in the fifth aspect, the first strainer portion is formed as one piece with the first separator portion of the separator, the second strainer portion is formed as one piece with the second separator portion of the separator, and the first separator portion and the second separator portion are coupled together. Thus, the strainer can be easily mounted to the separator, thereby reducing the number of processes of assembly.

In the sixth aspect, the straightening means straightens a flow of oil on the oil guide surface, thereby preventing disturbances of the oil flow. As a result, mixture of air in oil due to disturbance of the oil flow can be reduced, thereby reducing degradation of lubrication performance of oil.

In the seventh aspect, the interference prevention portion formed to avoid interference with the protrusion of the oil pan body is utilized to guide oil returned after having circulated in parts of the power unit, to the suction-member-placement region of the first reservoir along the oil guide surface formed in the interference prevention portion. Accordingly, oil warmed after having circulated in parts of the power unit is supplied to the power unit through a member for sucking oil again before the oil is cooled, thereby allowing oil exhibiting high lubrication performance to be supplied to the power unit.

In the eighth aspect, oil returned after having circulated in parts of the power unit, collected in the oil passageway, and dropped from the downstream end of the oil passageway, is guided to the suction-member-placement region along the oil guide surface. Accordingly, the contact area of oil returned from the power unit with the separator per a unit amount of oil can be reduced, and thus, oil warmed in the power unit can be guided to the suction-member-placement region while being kept warm. As a result, as in the first aspect, oil exhibiting high lubrication performance can be supplied to the power unit again.

DETAILED DESCRIPTION

An embodiment of the present invention will be described in detail hereinafter with reference to the drawings. The following embodiment is merely examples in nature, and is not intended to limit the scope, applications, and use of the invention.

FIG. 1illustrates an oil pan1according to the present invention. The oil pan1is for use in an engine (a power unit) E to be placed in an engine compartment at the front of an automobile, and is attached to a lower portion of the engine E, as illustrated inFIG. 2. Oil accumulated in the oil pan1is supplied to, and circulates in, parts of the engine E, and then returns to the oil pan1. The engine E placed in the engine compartment is positioned such that the crank shaft extends in the right-to-left direction of the automobile.

In the embodiment, the front side of the automobile is referred as the “front,” the rear side of the automobile is referred to as the “rear,” the left side of the automobile is referred as the “left,” and the right side of the automobile is referred as the “right,” for convenience of description.

As illustrated inFIG. 1, the oil pan1includes: an oil pan body2having a reservoir21which is open at the top thereof and stores oil; and a separator3having an annular sidewall unit4located in the oil pan body2and extending vertically. The separator3partitions the reservoir21into a first reservoir21alocated inside the separator3and a second reservoir21blocated outside the separator3. In this embodiment, the temperature of oil in the first reservoir21ais higher than the temperature of oil in the second reservoir21b. As illustrated inFIG. 2, the separator3is located in the oil pan body2such that a gap S is formed between the bottom of the sidewall unit4of the separator3and the oil pan body2. Oil accumulated in the reservoir21is allowed to flow between the first reservoir21aand the second reservoir21bthrough the gap S.

The oil pan body2is an injection molded part made of resin and having the shape of a substantially rectangular parallelepiped. As illustrated inFIGS. 1 and 2, the oil pan body2includes: a bottom wall23which is substantially rectangular in plan view; and a peripheral wall24rising from the periphery of the bottom wall23. As illustrated inFIG. 1, the reservoir21of this embodiment is a component for storing oil, formed by the bottom wall23and the peripheral wall24rising from the periphery of the bottom wall23.

As illustrated inFIGS. 1 and 2, the bottom wall23is long in the right-to-left direction, and an upward step25is formed on a left portion of the bottom wall23. The step25extends from the left end of the bottom wall23to a portion at the left of the middle of the bottom wall23in the right-to-left direction. Protrusions26and26directed toward the reservoir21are respectively formed at the front and rear edges of the bottom wall23, and extend from the left end of the bottom wall23to portions at the right of the middle of the bottom wall23in the right-to-left direction. As illustrated inFIG. 2, the tops of the protrusions26and26are located above the step25. As illustrated inFIG. 1, partitions23a,23a, . . . projecting upward and partially surrounding the bottom of the separator3, are formed on the bottom wall23of the oil pan body2. A gap23bis provided between each adjacent ones of the partitions23a, thereby allowing oil to flow between the first reservoir21aand the second reservoir21bthrough the partitions23a. Accordingly, even when the oil pan1is inclined, the partitions23aenable oil to accumulate in the first reservoir21a, thereby keeping the oil level higher than a strainer5, which will be described later. As a result, it is possible to prevent air from being sucked into the strainer5.

The suction-member-placement region22herein is a region enclosed by chain double-dashed lines inFIG. 2, and is located on the bottom of the reservoir21at the right of the middle, in the front-to-rear direction, of the reservoir21. An oil suction port57bof the strainer5is located in this suction-member-placement region22when the separator3is placed in the oil pan body2.

A flange27projecting outward is formed on the upper periphery of the peripheral wall24to be perpendicular to the peripheral wall24. The flange27has a plurality of fastening holes H1though which fastening bolts (not shown) for fastening the oil pan body2to the engine E are inserted.

As illustrated inFIG. 1, a left portion of the peripheral wall24of the oil pan body2is configured to be fastened to a casing (not shown) of a transmission. As illustrated inFIGS. 1 and 2, sidewall flanges28and28respectively projecting forward and downward are provided on the left portion of the peripheral wall24. A projection29projecting to the left is continuously formed on the front and bottom edges of the sidewall flanges28. Notches29aand29aare formed in the left edge of a portion of the projection29on the bottom edge of the sidewall flanges28, and are symmetric with respect to the middle, in the front-to-rear direction, of the oil pan body2. Bolt-insertion holes Bh1through Bh3through which fastening bolts (not shown) for fastening the oil pan1to the casing (not shown) of the transmission are formed in the projection29to penetrate the projection29in the right-to-left direction. The bolt-insertion hole Bh1is located in a front upper portion of the projection29. The bolt-insertion hole Bh2is located in a front lower portion of the projection29at a position associated with one of the protrusions26. In the same manner, the bolt-insertion hole13h3is located at a rear lower portion of the projection29at a position associated with the other protrusion26. Accordingly, when fastening bolts (not shown) are inserted in the bolt-insertion holes Bh2and Bh3to fasten the oil pan1to the casing (not shown) of the transmission, the protrusions26can prevent tools for fastening the fastening bolts (not shown) to the oil pan1and the oil pan1from interfering with each other.

The separator3is disposed in the oil pan body2, and is open at its top and bottom. The separator3includes: the sidewall unit4described above; and the strainer5which filters oil to be accumulated in the reservoir21before the oil circulates in parts of the engine E so as to remove impurities.

As illustrated inFIGS. 3 and 4, the width of the sidewall unit4in the right-to-left direction is larger than the width of the sidewall unit4in the front-to-rear direction in plan view. As illustrated inFIGS. 7A and 7B, an interference prevention portion6for preventing the oil pan body2from interfering with the protrusion26is provided in a left portion of a front sidewall of the sidewall unit4. The interference prevention portion6is recessed toward the first reservoir21a. As illustrated inFIG. 7B, a right portion of the interference prevention portion6is recessed toward the first reservoir21aalong the protrusion26of the oil pan body2. As illustrated inFIG. 7A, in a left portion of the interference prevention portion6, an upper portion is recessed toward the first reservoir21amore greatly than a lower portion, the lower portion is formed along the protrusion26, and a gap with a given size is formed between the interference prevention portion6and the protrusion26. The gap formed between the protrusion26and the interference prevention portion6is large enough to prevent the protrusion26and the interference prevention portion6from coming into contact with each other upon vibration of the engine E. The interference prevention portion6does not need to be formed along the protrusion26. As illustrated inFIGS. 3 and 4, an inclined portion (an oil guide surface)61gradually rises toward the left end is formed in a left portion of the interference prevention portion6. The top of the inclined portion61is located on the upper periphery of the sidewall unit4. As illustrated inFIG. 1, the downstream end of a return pipe Rt which is part of an oil passageway for guiding oil returned from the engine E to the inclined portion61, is located above the inclined portion61. Most part of oil circulated in parts of the engine E is collected in the return pipe Rt. The collected oil is returned to the inclined portion61through the return pipe Rt, and flows toward the suction-member-placement region22of the first reservoir21aalong the inclined portion61. Accordingly, oil returned after having circulated in parts of the engine E, collected in the return pipe Rt, and dropped from the downstream end of the return pipe Rt into the inclined portion61, is guided to the suction-member-placement region22along the inclined portion61. Thus, the contact area of oil from the engine E with the inclined portion61per a unit amount of oil can be reduced, and thereby, oil warmed in parts of the engine E is guided to the suction-member-placement region22while being kept warm.

A plate-like inclined wall62projecting upward and extending along the inclined portion61is fanned on the rear periphery of the inclined portion61. A communication hole (a communication portion)64communicating with the first reservoir21aand the second reservoir21bis formed in a left portion of the inclined portion61, i.e., immediately under the return pipe Rt. An opening/closing plate (an oil receiver)65is attached to the inclined portion61to close the communication hole64. The opening/closing plate65is in the shape of a substantially rectangular plate, and is tilted along the slope of the inclined portion61. The opening/closing plate65is located above the inclined portion61, and is close to the downstream end of the return pipe Rt. Accordingly, the opening/closing plate65can receive oil dropped from the downstream end of the return pipe Rt at a position closer to the downstream end, thereby reducing mixture of air in oil during dropping of the oil, as much as possible. A central shaft65aextending in the front-to-rear direction is provided at the middle, in the right-to-left direction, of the opening/closing plate65to intersect a flow of oil on the inclined portion61. The front and rear ends of the central shaft65aare rotatably attached to the sidewall unit4and the interference prevention portion6, respectively. As illustrated inFIG. 3, the front end of the central shaft65apenetrates the sidewall unit4, and projects forward from the sidewall unit4. The front end of the central shaft65ais connected to a known actuator Ac (illustrated inFIG. 1). The actuator Ac allows the opening/closing plate65to be rotatable about the central shaft65a. An opening/closing means9according to the present disclosure includes the opening/closing plate65and the actuator Ac. When the temperature of oil in the first reservoir21ameasured with, for example, a temperature sensor provided in the first reservoir21ais higher than a set value, the actuator Ac causes the opening/closing plate65to rotate counterclockwise about the central shaft65aas viewed from the front. Then, the right half of the opening/closing plate65is positioned to extend downward from the central shaft65a, and the left half of the opening/closing plate65is positioned to extend upward from the central shaft65a, thereby opening the communication hole64. Accordingly, when it is determined that the temperature of oil in the first reservoir21aexcessively increases to degrade lubrication performance of the oil, oil returned from the return pipe Rt is guided to the second reservoir21b. On the other hand, when the temperature sensor, for example, shows that the temperature of oil in the first reservoir21ais lower than the set value, the actuator Ac causes the opening/closing plate65to rotate clockwise about the central shaft65aas viewed from the front, and the opening/closing plate65closes the communication hole64to allow oil to flow along the inclined portion61. Accordingly, the temperature of oil in the first reservoir21aand the temperature of oil in the second reservoir21bcan be adjusted with the opening/closing plate65. The opening/closing plate65may be a thermostatic valve.

Two plate-like straightening vanes (straightening means)63projecting upward and extending along the inclined portion61are formed on the top surface of the inclined portion61. The two straightening vanes63are parallel to each other, and are disposed in the front-to-rear direction. The height of the straightening vanes63decreases toward the right. The upstream ends of the straightening vanes63in the oil flow are located at a right portion of the periphery of the communication hole64. These straightening vanes63straighten the flow of oil on the inclined portion61, and thus air is less likely to be mixed in the oil.

A plate-like attachment portion66projecting to the left is formed on top of the inclined portion61. A fastening hole h1through which a fastening bolt (not shown) is inserted in attaching the separator3to the engine E, is formed in the center of the attachment portion66, and vertically penetrates the attachment portion66. A bushing B is fitted into the fastening hole h1.

As illustrated inFIG. 1, a rear-wall protrusion4aprotruding forward is formed on a lower portion of a rear sidewall of the sidewall unit4. The rear-wall protrusion4ais a forward-projecting lower half of the rear sidewall of the sidewall unit4. As illustrated inFIG. 6, the front end of the rear-wall protrusion4ais located at a given distance from the strainer5. As illustrated inFIGS. 3 and 4, a rear-wall slope4brising toward the rear is formed in an upper portion of the rear sidewall of the sidewall unit4. The upper edge of the rear-wall slope4bis curved such that the middle, in the right-to-left direction, of the upper edge is at the highest position which is located above the top of a front sidewall of the sidewall unit4. A cylinder portion4cprojecting upward is formed on the middle, in the right-to-left direction, of the rear end of the rear-wall slope4b. A fastening hole h2through which a fastening bolt (not shown) is inserted in attaching the separator3to the engine E, is formed in the center of the cylinder portion4c, and vertically penetrates the cylinder portion4c. A bushing B is fitted into the fastening hole h2.

As illustrated inFIG. 2, the strainer5includes: a filter housing55housing a filter54for filtering oil; and a discharge pipe56connected to an oil pump (not shown).

The filter housing55forms an L shape in plan view, and more specifically, extends rearward from a portion between front and right sidewalls of the sidewall unit4along the right sidewall, and then bends to the left at the middle, in the front-to-rear direction, of the right sidewall. The left end of the filter housing55is located substantially at the center of the separator3. As illustrated inFIG. 5, the filter housing55is partitioned in the thickness direction into two: an upper portion (a first strainer portion)51located downstream; and a lower portion (a second strainer portion)52located upstream.

The upper portion51is formed as one piece with the sidewall unit4, and has a C shape in cross section. The C shape is made of an L-shaped upper wall51awhich extends rearward from a portion between the front and right sidewalls of the sidewall unit4along the right sidewall and then bends to the left at the middle, in the front-to-rear direction, of the right sidewall, and an upper peripheral wall51bprojecting downward from the periphery of the upper wall51a.

Plate-like bridges51cand51dconnected to the sidewall unit4are formed upstream of the upper portion51. The bridge51cis in the shape of an upright plate, and extends to the left and rear from a rear portion of the upstream end to be connected to the rear sidewall of the sidewall unit4. The bridge51dis in the shape of an upright plate, and connects an upstream portion of the front end of the upper portion51to the interference prevention portion6.

The discharge pipe56is provided downstream of the upper portion51, and is formed as one piece with the upper portion51. As illustrated inFIG. 3, the discharge pipe56is a circular pipe, and has an L shape. Specifically, the discharge pipe56extends straight upward from a portion of the top surface of the upper wall51abetween the right and front sidewalls of the sidewall unit4, then bends to the right at a position slightly above the top of the right sidewall of the sidewall unit4, and then extends straight. An oil outflow opening56ais formed in the discharge pipe56. The upstream end of the discharge pipe56is open, and communicates with the inside of the filter housing55. An oil outflow port56dis formed at the downstream end of the discharge pipe56.

A plate-like attachment portion56bobliquely extending to the bottom and rear is formed in a downstream portion of the discharge pipe56extending to the right. A fastening hole h3through which a fastening bolt (not shown) is inserted in attaching the separator3to the engine E, is formed in the attachment portion56b, and penetrates the attachment portion56bin the right-to-left direction. A bushing B is fitted into the fastening hole h3.

Two plate-like reinforcing ribs56cprojecting downward and connected to the right sidewall of the sidewall unit4are disposed side by side in the front-to-rear direction on an end portion of the projection of the attachment portion56b. Each of the reinforcing ribs56cis substantially an inverted triangle. Specifically, in each of the reinforcing ribs56c, the right side gradually approaches the left side to form a vertex at the bottom thereof.

As illustrated inFIGS. 5 and 6, the lower portion52has a C shape in cross section. The C shape is made of an L-shaped bottom wall52afacing the upper wall51aof the upper portion51and a lower peripheral wall52bprojecting upward from the periphery of the bottom wall52a. An oil suction port unit57is provided upstream of the lower portion52, and is formed as one piece with the lower portion52. As illustrated inFIG. 5, the oil suction port unit57is substantially rectangular in cross section, and projects downward from a left portion of the end of the bottom wall52a. An oil inflow opening57ais formed in the oil suction port unit57, and communicates with the inside of the filter housing55. An oil suction port57bis formed at the upstream end of the oil suction port unit57, and is located in the suction-member-placement region22of the first reservoir21a.

The filter54is made of a plate-like resin material, and as illustrated inFIG. 2, is placed between the upper portion51and the lower portion52.

The filter housing55may extend straight, or may be curved, in extending from the corner between the front sidewall and the right sidewall of the sidewall unit4to an approximate center of the separator3. In other words, the filter housing55only needs to have such a shape that the oil suction port57bof the filter housing55is located in the suction-member-placement region22.

Assembly of the oil pan1in the engine E will be described hereinafter. As illustrated inFIGS. 1 and 2, the separator3is placed under the engine E. Fastening bolts (not shown) are inserted in the fastening hole h1in the attachment portion66, the fastening hole h2in the cylinder portion4c, and the fastening hole h3in the attachment portion56b, to fasten the separator3to the engine E. Then, the oil pan body2is placed under the engine E to cover the separator3, and fastening bolts (not shown) are inserted into the fastening holes h in the flange27from blow the flange27, to fasten the oil pan body2to the engine E. In this placement, since the interference prevention portion6is formed in the separator3, the separator3does not interfere with the protrusion26of the oil pan body2, as illustrated inFIG. 7. In addition, as illustrated inFIG. 2, the bottom of the sidewall unit4of the separator3is located above the bottom wall23of the oil pan body2, and thus a gap S is formed between the bottom of the sidewall unit4and the bottom wall23to allow oil in the reservoir21to flow between the first reservoir21aand the second reservoir21b.

A flow of oil in the oil pan1will be described hereinafter. First, at a cold start, since the temperature of oil in the first reservoir21ais low, the opening/closing plate65closes the communication hole64so that oil circulated in parts of the engine E is collected in the return pipe Rt, returns from the downstream end of the return pipe Rt onto the opening/closing plate65of the interference prevention portion6, and flows on the inclined portion61to the suction-member-placement region22of the first reservoir21a, i.e., into a portion near the oil suction port57bof the strainer5. Accordingly, the contact area of oil from the engine E with the inclined portion61per a unit amount of oil can be reduced, and thus oil warmed in the engine E can be supplied to the engine E through the strainer5again while being kept warm. As a result, oil exhibiting low viscosity and high lubrication performance can be supplied to the engine E even immediately after a cold start, for example. Since the straightening vanes63are formed on the inclined portion61, the flow of oil on the inclined portion61is straightened, and thus air is less likely to be mixed in the oil. In addition, since the opening/closing plate65is located above the inclined portion61, the opening/closing plate65can be located closer to the downstream end of the return pipe Rt, and thus oil dropped from the downstream end of the return pipe Rt can be received at a position closer to the return pipe Rt. As a result, mixture of air in oil can be reduced as much as possible during dropping of the oil.

Thereafter, oil in the first reservoir21ais caused to circulate in parts of the engine E, thereby increasing the temperature of the oil in the first reservoir21a. When a temperature sensor (not shown) or the like provided in the first reservoir21ashows that the temperature of the oil in the first reservoir21ais higher than a set value, a known actuator Ac causes the opening/closing plate65to rotate, thereby opening the communication hole64. Accordingly, oil circulated in parts of the engine E and returned, can be guided to the second reservoir21b. Consequently, when the temperature of oil in the first reservoir21ais high, the opening/closing plate65is opened, thereby guiding oil returned from the engine E to the second reservoir21bthrough the communication hole64. When the temperature of oil in the first reservoir21ais low, the opening/closing plate65is closed, thereby allowing oil returned from the engine E to be guided to the first reservoir21aalong the inclined portion61. In this manner, the temperature of oil in the first reservoir21aand the temperature of oil in the second reservoir21bcan be adjusted.

As described above, in the oil pan1of this embodiment, oil returned after having circulated in parts of the engine E, collected in the return pipe Rt, and dropped from the downstream end of the return pipe Rt, can be guided to the suction-member-placement region22along the inclined portion61. Accordingly, the contact area of oil from the engine E with the inclined portion61per a unit amount of oil can be reduced. Oil warmed in the engine E can be guided to the suction-member-placement region22while being kept warm. As a result, oil having low viscosity and high lubrication performance can be supplied to the engine E again even immediately after a cold start of the engine E.

In addition, since the opening/closing plate65is located above the inclined portion61, the opening/closing plate65can be located closer to the downstream end of the return pipe Rt, and thus oil dropped from the downstream end of the return pipe Rt can be received at a position closer to the return pipe Rt. Accordingly, mixture of air in oil can be reduced as much as possible during dropping of the oil, thereby oil exhibiting high lubrication performance can be supplied to the engine E again.

Further, when the temperature of oil in the first reservoir21ais lower than a given temperature, the opening/closing plate65closes the communication hole64to guide oil returned from the engine E to the first reservoir21a. On the other hand, when the oil temperature is equal to or higher than the given temperature, the opening/closing plate65opens the communication hole64to guide oil returned from the engine E to the second reservoir21bthrough the communication hole64. Accordingly, the temperature of oil in the first reservoir21aand the temperature of oil in the second reservoir21bcan be adjusted.

Moreover, the upper portion51is formed as one piece with the separator3.

Accordingly, when the lower portion52is mounted to the upper portion51, the relative positions of the strainer5and the inclined portion61are less likely to be shifted. In this configuration, oil warmed while having circulated in parts of the engine E can always return to the same place in the oil suction port unit57of the strainer5. Thus, oil exhibiting high lubrication performance can be continuously supplied to the engine E. Moreover, since the upper portion51is formed as one piece with the separator3and the lower portion52is mounted to the upper portion51, the strainer5can be easily mounted to the separator3, thereby reducing the number of processes of assembly.

Furthermore, since the straightening vanes63straighten the flow of oil on the inclined portion61of the interference prevention portion6, the flow of oil cannot be disturbed. Accordingly, mixture of air in oil due to disturbance of the oil flow can be reduced, thereby reducing degradation of lubrication performance of oil.

The interference prevention portion6formed to avoid interference with the protrusion26of the oil pan body2is utilized to guide oil returned after having circulated in parts of the engine E, to the suction-member-placement region22of the first reservoir21aalong the inclined portion61formed in the interference prevention portion6. Accordingly, oil warmed while having circulated in parts of the engine E is supplied to the engine E again through the strainer5before the oil is cooled. As a result, oil exhibiting high lubrication performance can be supplied to the engine E.

FIGS. 8-11illustrate a modified example of the embodiment. This modified example is similar to the above embodiment except for aspects to be described below. The same reference numerals denote the same components in the embodiment, and only different aspects will be described in detail. Specifically, in the modified example, as illustrated inFIG. 8, a separator10is vertically partitioned into two, i.e., is formed by coupling an upper separator portion (a first separator portion)7and a lower separator portion (a second separator portion)8together.

FIG. 10illustrates the lower separator portion8of the separator10. The lower separator portion8is an injection molded part in which a lower sidewall81, as a lower part when the sidewall unit4is vertically divided into two, a bottom wall82covering a lower portion of the lower sidewall81, and a lower portion52are formed as one piece. As illustrated inFIG. 11, a right bottom wall82a, which is a right half of the bottom wall82, is located above a left bottom wall82b, which is a left half of the bottom wall82, to form a level difference. The right bottom wall82ais at the same level as the bottom wall52aof the lower portion52. The bottom of the oil suction port57bformed in the lower portion52is slightly apart from the left bottom wall82b, thereby allowing oil in a first reservoir21ato be sucked.

A through hole82cis formed in the left bottom wall82bto vertically penetrate the left bottom wall82b, thereby allowing oil to flow between the first reservoir21aand a second reservoir21b. This through hole82ccan also be used as a drain hole in exchanging oil. Accordingly, the through hole82cis preferably located at the lowest level in the bottom wall82in order to facilitate oil draining from the first reservoir21a. InFIG. 10, the through hole82cis located substantially at the center of the left bottom wall82bof the first reservoir21a, but may be located near a curved portion of the bottom wall82at the left of the lower sidewall81. In this case, the through hole82cis located away from the oil suction port unit57, and thus oil in the second reservoir21bat a temperature lower than that of oil is the first reservoir21ais less likely to be sucked from the oil suction port unit57through the through hole82c. Accordingly, in a cold start, for example, the temperature of oil in the first reservoir21acan be increased more quickly, thereby allowing oil with high lubrication performance to be continuously supplied to the engine E.

Two through holes82dare formed to penetrate a left portion of the lower sidewall81in the right-to-left direction, and are disposed side by side in the front-to-rear direction, thereby allowing oil to flow between the first reservoir21aand the second reservoir21b. Alternatively, a plurality of through holes82cmay be provided, and the number of through holes82dis not specifically limited.

As illustrated inFIG. 10, the first reservoir21ais surrounded by the lower sidewall81and the bottom wall82, and oil flows between the first reservoir21aand the second reservoir21bthrough the through hole82cand the through holes82d. Accordingly, as compared to a case where the bottom wall82is not provided below the lower sidewall81, heat is less likely to be removed from oil in the first reservoir21aby oil in the second reservoir21b. As a result, in a cold start, for example, the temperature of oil in the first reservoir21acan be increased more quickly, thereby allowing oil with high lubrication performance to be continuously supplied to the engine E.

As described above, the upper sidewall71, the upper portion51, and the discharge pipe56are formed as one piece to form the upper separator portion7. The lower sidewall81and the lower portion52are formed as one piece to form the lower separator portion8. Then, the upper separator portion7and the lower separator portion8are coupled together to form the separator10. Accordingly, in assembly of the separator10, the relative positions of the strainer5and the inclined portion61formed in the interference prevention portion6are less likely to be shifted. Accordingly, oil warmed after having circulated in parts of the engine E can always return to the same position in the oil suction port unit57of the strainer5. As a result, oil with high lubrication performance can be continuously supplied to the engine E.

Since the upper portion51is formed as one piece with the upper separator portion7of the separator10, the lower portion52is formed as one piece with the lower separator portion8of the separator10, and the upper separator portion7and the lower separator portion8are coupled together, the strainer5can be easily mounted to the separator10, thereby reducing the number of processes of assembly.

In the modified example of the embodiment, the separator3is vertically divided into two. Alternatively, the separator3may be divided in the right-to-left direction or in the front-to-rear direction.

In the modified example of the embodiment, the bottom wall82is provided in the lower separator portion8. Alternatively, the bottom wall82may not be provided.

The suction-member-placement region22may be located in any portion of the first reservoir21aas long as the suction-member-placement region22is located downstream of oil flowing on the inclined portion61.

The filter housing55may have an L shape extending from the corner between the front sidewall and the right sidewall to the rear sidewall of the sidewall unit4and then bends to the left along the rear sidewall, and may be in any shape as long as the oil suction port57bof the filter housing55is located in the suction-member-placement region22.

The oil pan body2and the separator3are not necessarily individually fastened to the engine E, and may be fastened together to the engine E. A configuration in which the separator3is mounted to the oil pan body2and then the oil pan body2is fastened to the engine E, may also be employed.

The oil pan body2is not necessarily an injection molded part made of resin, but may be made of iron or an aluminum alloy.

Oil returned from parts of the engine E to the inclined portion61is not necessarily returned from the downstream end of the return pipe Rt, and may be returned to the inclined portion61from the downstream end of an oil passageway provided in the wall of an engine block, for example.

The opening/closing plate65may be located at any position of the inclined portion61as long as the opening/closing plate65is located at a higher level than the oil surface in the reservoir21.

The straightening vanes63may be provided to a portion of the opening/closing plate65toward the first reservoir21a.

The height of the straightening vanes63may gradually increase toward the right, or may be at an even level.

The present disclosure is also applicable to an oil pan of a power unit such as an automatic transmission.

INDUSTRIAL APPLICABILITY

The present disclosure is useful for an oil pan which stores oil circulated in a power unit in an automobile, for example, and a separator for separating the inside of the oil pan.