Patent Publication Number: US-6340012-B1

Title: Oil pan for internal combustion engine

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an oil pan for an internal combustion engine, which is mounted on an underside of an engine cylinder block, and more specifically to an oil pan having a baffle plate. 
     Japanese Patent Application First Publication No. 7-42523 discloses an oil pan for an internal combustion engine, which has a double-walled structure including an inner pan and an outer pan with a very small clearance therebetween. Lubricating oil drained from the engine is introduced to the very small clearance to form a thin oil layer therein. Each of the outer and inner pans includes a deep oil collecting portion and a shallow oil collecting portion which are disposed adjacent to each other in a longitudinal direction of the engine. The shallow oil collecting portion is disposed near an engine rotating part such as a crankshaft. A baffle plate extends over the inner-and outer pans to restrain an oil level of the lubricating oil within the oil pan from swinging during operation of a vehicle. The baffle plate has a plurality of oil guide holes through which the lubricating oil dripped from a part, for instance, a crankshaft journal, near the oil pan is collected at the shallow oil collecting portion. 
     SUMMARY OF THE INVENTION 
     It will be noted that such a conventional oil pan as the above-described related art is complicated by the double-walled structure and therefore the lubricating oil drained from the engine and the lubricating oil dripped from the adjacent part such as the crankshaft journal are collected at the separate portions, i.e., the clearance between the inner and outer pans and the shallow oil collecting portion of the inner pan. Further, in the conventional oil pan, the baffle plate, except the oil holes thereof, covers the entire shallow oil collecting portion and further no measure is taken for forcing the lubricating oil collected at the shallow oil collecting portion toward the deep oil collecting portion. This will prevent the lubricating oil dripped from the crankshaft journal from being smoothly directed to the deep oil collecting portion via the oil guide holes and the shallow oil collecting portion. In such a case, the lubricating oil within the shallow oil collecting portion tends to be contacted with the crankshaft and stirred thereby. If the lubricating oil is stirred by the contact with the crankshaft, air is undesirably mixed in the lubricating oil. In addition, if the crankshaft is contacted with an oil level of the lubricating oil within the shallow oil collecting portion, friction loss caused by the contact therebetween will be increased. 
     It is an object of the present invention to provide an oil pan having a simple structure and capable of quickly collecting a lubricating oil at a deep oil collecting portion through a shallow oil collecting portion. 
     It is a further object of the present invention to provide an oil pan capable of controlling an oil level of the lubricating oil collected at the shallow oil collecting portion so as not to be in contact with an engine rotating part. 
     According to one aspect of the present invention, there is provided an oil pan for collecting a lubricating oil drained from an internal combustion engine and a lubricating oil dripped from a crankshaft of the engine, said oil pan being disposed near the crankshaft, comprising: 
     a wall including a first oil collecting portion and a second oil collecting portion that are adapted for collecting the lubricating oils, said first and second oil collecting portions being connected with and adjacent to each other in a longitudinal direction of the engine; 
     a first baffle plate cooperating with the first oil collecting portion of the wall to define a first oil passage extending along the longitudinal direction of the engine, said first oil passage being disposed downstream of a rotating direction of the crankshaft perpendicular to the longitudinal direction of the engine, said first oil passage having an inlet portion open in a direction opposed to the rotating direction of the crankshaft; 
     a second baffle plate cooperating with the first oil collecting portion of the wall to define a second oil passage extending along the longitudinal direction of the engine and spaced from the first oil passage in a lateral direction of the engine perpendicular to the longitudinal direction, said oil passage being disposed upstream of the rotating direction of the crankshaft; and 
     a plurality of oil guides guiding the lubricating oil drained from the engine to the first and second oil passages, said plurality of oil guides being disposed on the first and second baffle plates, respectively; 
     wherein said first and second oil passages are so arranged as to force the lubricating oil collected at the first oil collecting portion toward the second oil collecting portion. 
     According to a further aspect of the present invention, there is provided an oil pan for collecting a lubricating oil drained from an internal combustion engine and a lubricating oil dripped from a crankshaft of the engine, said oil pan being disposed near the crankshaft, comprising: 
     a first oil collecting portion for collecting the lubricating oils; 
     a second oil collecting portion for collecting the lubricating oils, said second oil collecting portion being adjacent to the first oil collecting portion in a longitudinal direction of the engine and connected therewith; 
     first wall means for defining the first and second oil collecting portions; 
     a first oil passage extending along the longitudinal direction of the engine and disposed downstream of a rotating direction of the crankshaft perpendicular to the longitudinal direction of the engine, said first oil passage having an inlet portion open in a direction opposed to the rotating direction of the crankshaft; 
     a second oil passage extending along the longitudinal direction of the engine and spaced from the first oil passage in a lateral direction of the engine perpendicular to the longitudinal direction, said second oil passage being disposed upstream of the rotating direction of the crankshaft; 
     second wall means cooperating with the first oil collecting portion of the first wall means to define the first oil passage; and 
     third wall means cooperating with the first oil collecting portion of the first wall means to define the second oil passage; 
     wherein said second and third wall means forcibly guide the lubricating oil collected at the first oil collecting portion toward the second oil collecting portion. 
     According to a still further aspect of the present invention, there is provided an oil pan for collecting a lubrication oil drained from an internal combustion engine and a lubricating oil dripped from a rotating part of the engine, said oil pan being disposed near the rotating part, comprising: 
     a first oil collecting portion for collecting the lubricating oils; 
     a second oil collecting portion for collecting the lubricating oils, said second oil collecting portion being adjacent to the first oil collecting portion in a longitudinal direction of the engine and connected therewith; 
     first means, downstream of a rotating direction of the rotating part, for enabling the lubricating oil collected at the first oil collecting portion to be introduced thereinto by wind force caused upon rotation of the rotating part and be forced toward the second oil collecting portion; and 
     second means, upstream of the rotating direction of the crankshaft, for preventing the lubricating oil collected at the first oil collecting portion from being influenced by the wind force and for forcing the lubricating oil collected thereat toward the second oil collecting portion; 
     wherein said first and second means cooperate to facilitate collection of the lubricating oil through the first oil collecting portion and control an oil level of the lubricating oil collected at the first oil collecting portion so as not to be in contact with the rotating part. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view of an oil pan of a first embodiment, according to the present invention; 
     FIG. 2 is a cross section, taken along the line  2 — 2  of FIG. 1; 
     FIG. 3 is a cross section, taken along the line  3 — 3  of FIG. 1; 
     FIG. 4 is a cross section, taken along the line  4 — 4  of FIG. 1; and 
     FIG. 5 is a cross section similar to FIG. 2, but showing the oil pan of a second embodiment, according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to FIGS. 1-4, there is shown an oil pan  10  according to the present invention, which is applicable to a V-type internal combustion engine. The oil pan  10  is adapted to be mounted to an underside of an engine cylinder block. The oil pan  10  is adapted for collecting a lubricating oil drained from the engine and a lubricating oil dripped from an engine part, for instance, a crankshaft journal. 
     As illustrated in FIG. 1, the oil pan  10  is formed with a flange  12  extending along a circumferential periphery of an upper end portion thereof. The oil pan  10  is fixed to the underside of the engine cylinder block by tightening bolts, not shown, at the flange  12 . The oil pan  10  includes a deep oil collecting portion  14  and a shallow oil collecting portion  16  that are located adjacent to each other in a longitudinal direction of the engine. The shallow oil collecting portion  16  has a depth smaller than a depth of the deep oil collecting portion  14 . The deep oil collecting portion  14  and the shallow oil collecting portion  16  are connected with each other through a sloped intermediate portion  15 , as shown in FIG.  2 . The oil pan  10  is made of an aluminum alloy. The deep oil collecting portion  14  and the shallow oil collecting portion  16  are integrally formed in this embodiment but may be formed as separate parts and connected together. The deep oil collecting portion  14  includes a generally rectangular and flat bottom wall and a peripheral side wall connected with the bottom wall. Similarly, the shallow oil collecting portion  16  includes a generally rectangular and flat bottom wall and a peripheral side wall connected with the bottom wall. The bottom wall of the shallow oil collecting portion  16  is positioned at a level higher than the bottom wall of the deep oil collecting portion  14 , as shown in FIG.  2 . 
     As illustrated in FIG. 3, the shallow oil collecting portion  16  is disposed near below an engine rotating part, such as a big end  18   a  of a connecting rod of a crankshaft  18 . The arrangement of the shallow oil collecting portion  16  relative to the engine rotating part is made because of a limited installation space in a vertical direction of the engine. 
     Referring back to FIG. 1, the shallow oil collecting portion  16  includes a first oil passage  20  and a second oil passage  22  on opposed sides of the shallow oil collecting portion  16  in a lateral direction of the engine perpendicular to the longitudinal direction. The oil passages  20  and  22  are spaced from each other in the lateral direction and extend toward the deep oil collecting portion  14  along the longitudinal direction. The oil passage  20  is disposed downstream of a rotating direction ω of the crankshaft  18  and the oil passage  22  is disposed upstream of the rotating direction ω of the crankshaft  18 , as shown in FIG.  3 . The oil passages  20  and  22  are so arranged as to force the lubricating oil collected at the shallow oil collecting portion  16  toward the deep oil collecting portion  14 , as explained hereinafter. 
     The oil passage  20  is defined by a first baffle plate  24 , a plurality of guide ribs  40 A- 40 C and the bottom and side walls of the shallow oil collecting portion  16 . The oil passage  20  has a generally rectangular shape in cross section, as shown in FIG.  4 . Specifically, the first baffle plate  24  is fixed to a lateral side, i.e., an upper side as viewed in FIG. 1, of the shallow oil collecting portion  16 , by tightening bolts, not shown, at bosses  28 A- 28 E and  28 K. The baffle plate  24  is made of a thin sheet metal and has a generally elongated rectangular shape shown in FIG.  1 . The baffle plate  24  extends along the longitudinal direction of the engine over the lateral side portion of the shallow oil collecting portion  16  to cover the lateral side portion thereof. As shown in FIG. 4, the baffle plate  24  covers a trough formed by the guide rib  40 A and the bottom and side walls of the shallow oil collecting portion  16 . The baffle plate  24  has an underside surface defining an upper periphery of the rectangular oil passage  20 . As shown in FIG. 2, the baffle plate  24  has an inclined longitudinal end portion  24   a  inclined downwardly toward the deep oil collecting portion  14  along the sloped intermediate portion  15  between the deep and shallow oil collecting portions  14  and  16 . As shown in FIG. 3, the baffle plate  24  also has an inclined lateral-inner flange  24   b  extending laterally inwardly from a lateral-inner side thereof and inclined upwardly. The lateral-inner flange  24   b  serves for positively introducing the lubricating oil dripped onto the shallow oil collecting portion  16  into the oil passage  20  through the inlet portion  38 . 
     In this embodiment, the three guide ribs  40 A- 40 C are spaced from each other in the longitudinal direction of the engine and define therebetween two inlet portions  38  of the oil passage  20 . Each inlet portion  38  is open in a direction opposed to the rotating direction ω of the crankshaft  18 , as shown in FIG.  3 . The guide ribs  40 A- 40 C are integrally formed with the bottom wall of the shallow oil collecting portion  16 . The guide ribs  40 A- 40 C extend uprightly from the bottom wall of the shallow oil collecting portion  16  in a spaced and opposed relation to the side wall thereof. The guide ribs  40 A- 40 C act as a lateral-inner wall defining a lateral-inner periphery of the rectangular oil passage  20 . The guide ribs  40 A- 40 C are smoothly curved from the inlet portions  38  toward the deep oil collecting portion  14 , as shown in FIG.  1 . In other words, the guide ribs  40 A- 40 C are curved from the deep oil collecting portion  14  side toward a lateral-central portion of the shallow oil collecting portion  16 . Opposed lateral-inner end portions of the adjacent two guide ribs  40 A and  40 B, and  40 B and  40 C, cooperate to form the inlet portion  38  therebetween. The lateral-inner end portions of the guide ribs  40 A- 40 C associate with the inclined lateral-inner flange  24   b  of the baffle plate  24  for positive introduction of the lubricating oil. Among the guide ribs  40 A- 40 C, the guide rib  40 A is positioned closest to the deep oil collecting portion  14 . The guide ribs  40 A- 40 C have upper ends contacted with the underside surface of the baffle plate  24  and support the baffle plate  24  in association with the bosses  28 A- 28 E and  28 K. The bosses  28 D and  28 E are integrally formed with the guide ribs  40 A and  40 B, respectively. 
     The oil passage  22  is defined by a second baffle plate  26 , a guide rib  42  and the bottom and side walls of the shallow oil collecting portion  16 . The oil passage  22  has a generally rectangular shape in cross section as best shown in FIG. 4, similar to the oil passage  20 . The second baffle plate  26  is fixed to the opposite lateral side, i.e., a lower side as viewed in FIG. 1, of the shallow oil collecting portion  16 , by tightening bolts, not shown, at bosses  28 F- 28 J. The baffle plate  26  is made of a thin sheet metal and has a generally elongated rectangular shape shown in FIG.  1 . The baffle plate  26  extends along the longitudinal direction of the engine over the opposite lateral side portion of the shallow oil collecting portion  16  to cover the opposite lateral side portion thereof. As shown in FIG. 4, the baffle plate  26  covers a trough formed by the guide rib  42  and the bottom and side walls of the shallow oil collecting portion  16 . The baffle plate  26  has an underside surface defining an upper periphery of the rectangular oil passage  22 . As shown in FIG. 2, the baffle plate  26  has an inclined longitudinal end portion  26   a  inclined downwardly toward the deep oil collecting portion  14  along the sloped intermediate portion  15  between the deep and shallow oil collecting portions  14  and  16 . 
     As illustrated in FIG. 1, the guide rib  42  extends along the longitudinal direction of the engine over substantially an entire length of the oil passage  22 . The guide rib  42  is inclined relative to a reference line L extending in the longitudinal direction of the engine in such a manner that the guide rib  42  becomes closer to the oil passage  20  as the guide rib  42  extends closer to the deep oil collecting portion  14 . The guide rib  42  has one end  42   a  distant from the deep oil collecting portion  14  and connected with the side wall of the shallow oil collecting portion  16 . The guide rib  42  also has an opposite end  42   b  located close to the deep oil collecting portion  14 . The guide rib  42  is integrally formed with the bottom wall of the shallow oil collecting portion  16 . The guide rib  42  extends uprightly from the bottom wall of the shallow oil collecting portion  16  in an opposed and spaced relation to the side wall thereof. The guide rib  42  acts as a lateral-inner wall defining a lateral-inner periphery of the rectangular oil passage  22 , as shown in FIG.  4 . The guide rib  42  has an upper end contacted with the underside surface of the baffle plate  26  and supports the baffle plate  26  together with the bosses  28 F- 28 J. The boss  28 I is integrally formed with the guide rib  42 . 
     There is a lateral-central area of the shallow oil collecting portion  16 , which is prevented from being covered with a baffle plate. The lateral-central area of the shallow oil collecting portion  16  is exposed to the big end  18   a  of the connecting rod of the crankshaft  18 , as shown in FIG.  3 . 
     A third baffle plate  30  extends over the deep oil collecting portion  14 . The baffle plate  30  is fixed to the deep oil collecting portion  14  by tightening bolts, not shown, at the bosses  28 J- 28 U. The baffle plate  30  is formed with a cutout  30   a  for preventing conflict with a suction pipe, not shown. The baffle plate  30  thus covers substantially an entire area of the deep oil collecting portion  14  to restrain an oil level of the lubricating oil collected at the deep oil collecting portion  14  from swinging during operation of the vehicle. As illustrated in FIG. 2, the baffle plate  30  is located at a level lower than a general surface of each baffle plate  24  and  26 . In this embodiment, the baffle plate  30  is separately formed from the baffle plates  24  and  26 . The baffle plate  30  extends over lower ends of the inclined longitudinal end portions  24   a  and  26   a  of the baffle plates  24  and  26 . The baffle plate  30  may extend over the lower end portion  24   a  or  26   a  of at least one of the baffle plates  24  and  26 . 
     A plurality of oil guides, four oil guides  32 A- 32 D in this embodiment, are mounted onto the lateral-outer sides of the baffle plates  24  and  26  through flanges  34 . The oil guides  32 A- 32 D are in the form of a generally tubular shape extending upwardly as shown in FIG.  2 . The oil guides  32 A and  32 B have lower ends open into the oil passage  20  through the baffle plate  24 , respectively. The oil guides  32 C and  32 D have lower ends open into the oil passage  22  through the baffle plate  26 , respectively. The oil guides  32 A- 32 D are arranged to be opposed to oil drain holes indicated at  36 A- 36 D in FIG. 1, which are formed in the engine parts such as an engine cylinder head and an engine cylinder block. The oil guides  32 A- 32 D are effective to guide the lubricating oil drained through the oil drain holes  36 A- 36 D to the oil passages  20  and  22 . Oil drain holes  36 E- 36 G of the engine parts are located above the deep oil collecting portion  14 . An oil guide  32 E for the oil drain hole  36 E is mounted onto the baffle plate  30 . The oil guide  32 E has a generally reversed U-shape as shown in FIG.  1 . Meanwhile, the V-type engine, to which the oil pan of this embodiment is applied, has engine cylinder heads on the laterally opposed sides and a main oil gallery on the lateral-central portion. The oil drain holes  36 A- 36 G, therefore, are arranged on the laterally opposed sides of the V-type engine. 
     The thus-constructed oil pan collects the lubricating oil in the following manner. 
     The lubricating oil drained from the engine parts through the oil drain holes  36 A- 36 D flows into the oil passages  20  and  22  through the oil guides  32 A- 32 D, as indicated by arrows S 1  in FIGS. 1 and 2. The lubricating oils passing through the oil passages  20  and  22 , respectively, are forced toward the deep oil collecting portion  14  and gathered thereat. The lubricating oil drained from the engine parts through the oil drain holes  36 E- 36 G flows directly or through the oil guide  32 E into the deep oil collecting portion  14  and collected thereat. 
     On the other hand, the lubricating oil dripped from the engine parts, such as the crankshaft journal, onto the shallow oil collecting portion  16  is introduced into the oil passage  20  through the inlet portion  38  by the wind force caused upon rotation of the crankshaft  18 . Namely, the crankshaft  18  rotates at high speed in the direction ω shown in FIG. 3, in the crankcase, so that an air stream is produced along the rotating direction ω in the crankcase. The air stream pushes the lubricating oil dripped onto the shallow oil collecting portion  16 , whereby there is generated a flow of the lubricating oil having a velocity vector along the lateral direction of the engine, as indicated by arrows S 2  in FIGS. 1 and 3. The lubricating oil is urged to enter the oil passage  20  through the inlet portion  38 , passing through the oil passage  20 . The lubricating oil is thus forced toward the deep oil collecting portion  14  and collected thereat. 
     As be appreciated from the above description, the oil passages  20  and  22  cooperate to facilitate the collection of the lubricating oil through the shallow oil collecting portion  16 . The oil passages  20  and  22  force the lubricating oil drained from the engine parts through the oil drain holes  36 A- 36 D to quickly flow into the deep oil collecting portion  14 . This can reduce a period at which the lubricating oil stays at the shallow oil collecting portion  16 , so that an oil mist produced in the crankcase can be reduced. Further, an oil level of the lubricating oil collected at the lateral-central area of the shallow oil collecting portion  16  can be controlled so as not to be in contact with the rotating part of the crankshaft  18  and stirred thereby. As a result, the air density within the crankcase can be kept low and the friction loss caused by the contact of the rotating part of the crankshaft  18  with the oil level of the lubricating oil can be reduced. 
     The oil passage  20  can be effective to force both of the lubricating oils dripped onto the shallow oil collecting portion  16  and drained through the oil guides  32 A and  32 B toward the deep oil collecting portion  14 . The arrangement of the oil passage  20  is contributes to the simple structure of the oil pan  10 . 
     The inlet portion  38  of the oil passage  20 , that is open in the direction opposed to the rotating direction ω of the crankshaft  18 , can trap the lubricating oil dripped onto the shallow oil collecting portion  16  in the assistance of the air stream produced along the rotating direction ω of the crankshaft  18 . As a result, the period at which the lubricating oil stays at the shallow oil collecting portion  16  can be more reduced. 
     Further, the guide ribs  40 A- 40 C can impart such a proper vector as to direct toward the deep oil collecting portion  14  to the lubricating oil introduced through the inlet portion  38 . The lubricating oil is thus urged to quickly flow toward the deep oil collecting portion  14 . This can improve the oil collecting rate at the shallow oil collecting portion  16 . 
     The oil passage  22  is disposed upstream of the rotating direction ω of the crankshaft  18  and the guide rib  42  acts as a partition wall for separating the oil passage  22 . The lubricating oil introduced into the oil passage  22  through the oil guides  32 C and  32 D can be prevented from being influenced by the wind force caused upon rotation of the crankshaft  18  in the direction ω. The lubricating oil introduced into the oil passage  22  can be forced toward the deep oil collecting portion  14  without being pushed by the wind force downstream of the rotating direction ω of the crankshaft  18 . The lubricating oil can also be restrained from being excessively collected upstream of the rotating direction ω of the crankshaft  18 . This results in restricting an oil level of the lubricating oil collected upstream of the rotating direction ω of the crankshaft  18 , to a lower level. Further, the guide rib  42  inclined relative to the longitudinal reference line L can properly change the velocity vector of the flow of the lubricating oil passing through the oil passage  22 . This causes the flow of the lubricating oil to be quickly and smoothly directed toward the deep oil collecting portion  14 . The period at which lubricating oil stays at the shallow oil collecting portion  16 , therefore, can be reduced. 
     Furthermore, with the above-described arrangement of the baffle plate  30  relative to the baffle plates  24  and  26 , the lubricating oils passing through the oil passages  20  and  22 , respectively, can be positively introduced into the deep oil collecting portion  14  along below the end portions  24   a  and  26   a  of the baffle plates  24  and  26 , without flowing onto the baffle plate  30 . To this end, it is assured that the oil level of the lubricating oil collected at the shallow oil collecting portion  16  is controlled so as not to be in contact with the rotating part of the crankshaft  18  and stirred thereby. 
     Referring to FIG. 5, the oil pan of the second embodiment, according to the invention, will be explained hereinafter. The oil pan of the second embodiment is similar to that of the first embodiment except that three baffle plates are integrally formed. Like reference numbers denote like parts, and therefore, detailed explanations therefor can be omitted. 
     As illustrated in FIG. 5, the integral baffle plate includes first and second baffle plate portions  44  and  46  forming the oil passages  20  and  22 , respectively, and a third baffle plate portion  48  covering the deep oil collecting portion  14 . A sloped intermediate portion  50  is interposed between the baffle plate portions  44  and  46  and the baffle plate portion  48 . The sloped intermediate portion  50  is downwardly inclined toward the deep oil collecting portion  14 . The integral baffle plate is in the form of a thin sheet metal. 
     The arrangement of this embodiment can exhibit same effects as the effects of the first embodiment and reduce the number of parts of the oil pan. In addition, an oil pan using the integral baffle plate is suitably applicable to an internal combustion engine having a relatively small size. If it is difficult to apply the oil pan using the integral baffle plate to a relatively large-sized internal combustion engine, an oil pan having the separate baffle plates  24 ,  26  and  30  of the first embodiment may be applied thereto. 
     This application is based on Japanese Patent Application No. 11-126756, filed on May 7, 1999, the entire contents of which, inclusive of the specification, claims and drawings, are hereby incorporated by reference herein. 
     Although the invention has been described above by reference to certain embodiments of the invention, the invention is not limited to the embodiments described above. Modifications and variations of the embodiment described above will occur to those skilled in the art, in light of the above teachings. The scope of the invention is defined with reference to the following claims.