JP3730610B2 - Engine oil return passage - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a return passage for engine oil provided in an engine provided with a housing that rotatably receives a balancer shaft below a crankshaft.
[0002]
[Prior art]
The engine oil that has lubricated and cooled the valve mechanism provided in the cylinder head is returned to the oil pan through a return passage provided in the cylinder block or the like, but the mist of oil is not mixed into the blow-by gas. Therefore, it is preferable that the return oil does not touch the crankshaft rotating at a high speed in the crankcase.
[0003]
As a technique for this, a structure in which a pipe extending under the oil level in the oil pan is connected to the downstream end of the return path provided in the cylinder block, or a return path extending in the vicinity of the oil level is provided in the crankcase. Is proposed in Japanese Utility Model Laid-Open No. 61-1113910.
[0004]
[Patent Document 1]
Japanese Utility Model Publication No. 61-1113910 (FIGS. 1 and 2)
[0005]
[Problems to be solved by the invention]
According to the above-described conventional structure, those using pipes require a pipe made of a separate member, which increases the number of parts and increases the number of work steps for attaching the pipes. In addition, the crankcase with a return passage has a complicated crankcase mold, which increases the number of manufacturing steps, and the degree of freedom in setting the oil outlet is low, which increases the size of the crankcase. It is difficult to provide an oil drain port at a position that always immerses below the oil level with respect to changes in vehicle posture and driving conditions without inviting the vehicle.
[0006]
The present invention has been devised to solve such problems of the prior art, and its first object is to be formed without increasing the number of parts and the number of manufacturing steps. It is to provide a return passage for engine oil.
[0007]
A second object of the present invention is to provide a return passage for engine oil that can be provided with an oil discharge port without increasing the size of the engine at a position that is not easily affected by changes in vehicle posture or driving conditions. There is to do.
[0008]
[Means for Solving the Problems]
In order to achieve such an object, in the first aspect of the invention, the housing (14U / 14L) in which the balancer shaft (13L / 13R) is rotatably received is used as the engine block (the lower block 3 in the embodiment). In an engine joined to a portion positioned below the crankshaft (1) in the engine block , an engine oil return path for returning engine oil from the cylinder head side to the oil pan (5) is provided in the housing in the engine block. And a passage hole (41) opened in the joint surface and a passage hole (42a) provided in the housing are connected to each other . Further, in the invention of claim 2, the housing is joined to a portion of the lower block joined to the lower surface of the cylinder block and located below the crankshaft, and the return passage is connected to the housing in the lower block. And a passage hole opened in the joint surface and a passage hole provided in the housing are connected to each other.
[0009]
In this way, a passage hole is provided in the balancer shaft housing located below the crankshaft, and the passage hole provided in the engine block (lower block) is connected to the passage hole to thereby connect the passage from the cylinder head. Can be communicated with the lowermost part of the engine, so that an engine oil return passage opened below the oil level in the oil pan can be formed without increasing the number of parts and the number of manufacturing steps of the engine itself.
[0010]
According to a third aspect of the present invention, the housing is composed of an upper housing (14U) and a lower housing (14L) which are divided into upper and lower parts and joined to each other , and the return passage is formed along the joint surface between the two housings. At least a part of the groove (grooves 42b and 42c) is extended . As a result, it is relatively easy to route the passage so that the oil outlet is located at an arbitrary position without causing an increase in the size of the engine, and the momentum of the return oil is reduced by bending the passage. Therefore, the engine oil in the oil pan is not stirred.
[0011]
In the invention of claim 4, the oil discharge port (43) of the return passage that opens to the bottom surface of the housing (lower housing 14L) and the suction port (29) of the oil strainer (25) are connected to the balancer shaft (13L. 13R) is provided so as to be in contact with substantially the same plane orthogonal to the axis. As a result, the oil drainage port can be provided at a position close to the suction port of the oil strainer (25) that is always immersed below the oil level. Can be maintained under the oil level.
[0012]
In the invention of claim 5 , the portion (cylindrical portion 44) where the oil drain port is opened in the configuration of claim 4 is directly connected to the oil strainer mounting portion (28) integrally formed on the bottom surface of the housing. It was supposed to be. Thereby, not only is it not influenced by changes in the vehicle posture and the driving situation, but also the rigidity of the portion where the oil outlet is opened can be increased.
[0013]
In the invention of claim 6 , at least a part (vertical hole 42a) of the return passage is provided on a plane passing through the bearing hole (22c) of the balancer shaft and orthogonal to the axis of the balancer shaft. As a result, the return passage is provided in the vicinity of the bearing portion having a relatively high rigidity, so that the rigidity of the housing does not decrease even if the hole is formed.
[0014]
Furthermore, in the invention of claim 7, the housing is fastened with a bolt (B1) to a portion of the engine block located below the crankshaft, and at least a part of the return passage (vertical hole 42d) It was assumed that it extended along the axis of the bolt insertion hole at a position adjacent to the bolt insertion hole inside the bolt insertion hole (45) provided in the housing. Thereby, the enlargement of the housing by providing a return channel | path can be avoided.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
[0016]
1 and 2 show an engine to which the present invention is applied. The engine E is an in-line four-cylinder engine in which the crankshaft 1 extends in the horizontal direction, and includes a cylinder block 2, a lower block 3, a balancing device 4, and an oil pan 5. The cylinder axis is inclined with respect to the orthogonal direction and mounted on the vehicle body.
[0017]
The balancing device 4 is for reducing the secondary vibration of the engine E caused by the reciprocating motion of the piston, and an oil pan is provided by a plurality of through bolts B1 inserted into the left and right side ends from below. 5 is fastened to the lower surface of the lower block 3 (below the crankshaft 1). The balancing device 4 includes a large sprocket 7 fixed to the back side of the crank pulley 6 at the front end of the crankshaft 1 (hereinafter referred to as the crank pulley side), and the left side (hereinafter, the left and right direction toward the crank pulley). And a small sprocket 8 fixed to the front end of a balancer shaft (to be described in detail later) and a link chain 9 spanned between the large and small sprockets 6 and 7. The crankshaft 1 is driven to rotate by the rotational force of the crankshaft 1.
[0018]
The balancing device 4 includes a pair of left and right balancer shafts 13L and 13R having substantially the same shape, and the center of both balancer shafts 13L and 13R so as to support and accommodate these two balancer shafts 13L and 13R in parallel with each other. 14U, and an upper housing 14U and a lower housing 14L which are divided into two vertically along a plane passing therethrough.
[0019]
Both the balancer shafts 13L and 13R are linked to each other by a helical gear 15 (only one of which is shown) integrally coupled to the balancer shafts 13L and 13R. Here, as described above, the driving force of the crankshaft 1 is transmitted to the left balancer shaft 13L via the large sprocket 7, the small sprocket 8, and the link chain 9, and thus the rotational speed twice that of the crankshaft 1 is achieved. Thus, the left balancer shaft 13L is rotationally driven in the same direction as the crankshaft 1. The right balancer shaft 13R is rotationally driven in the opposite direction by the meshing of the helical gears 15.
[0020]
The balancer shafts 13L and 13R have relatively small-diameter first and second journal portions 16a and 16b integrally formed in front of the helical gear 15, and relatively large-diameter third and fourth journal portions 16c and 16d are helical gears. 15 is formed integrally with the rear. In addition, a counterweight part 17 is integrally formed at the rear part of each balancer shaft 13L and 13R, the position of the center of gravity being biased radially outward from the center of rotation, and being divided into two front and rear parts with the third journal part 16c interposed therebetween. Has been.
[0021]
Flange portions 18 having an enlarged diameter are formed at opposing ends of the front / rear counterweight portion 17 across the third journal portion 16c. Thrust receiving surfaces 19 are formed on the opposing end surfaces of the flange portions 18.
[0022]
The shaft portion 20 of the counterweight portion 17 has a relatively small diameter in order to obtain the expected equivalent rotational mass while making the counterweight portion 17 as small as possible. In order to compensate for the decrease in rigidity due to the reduced diameter, it is provided between the mounting portion of the helical gear 15 and the flange portion 18 provided on the front side of the third journal portion 16c and on the rear side of the third journal portion 16c. A rib 21 that connects the flange portion 18 and the fourth journal portion 16d in the axial direction is provided on a portion of the two shaft portions 20 that extends over the entire length on the opposite weight side. These ribs 21 are tapered so that the height dimension is reduced toward the center in the axial direction of each counterweight portion 17 in order to minimize the increase in weight due to the provision of the ribs 21 and to optimize the stress distribution. It is made into a shape.
[0023]
On the other hand, the journal portions 16a to 16d of both the balancer shafts 13L and 13R are supported by two divided first to fourth bearing holes 22a to 22d formed by joining the upper and lower housings 14U and 14L to each other. Is done.
[0024]
The journal portions 16a to 16d of the balancer shafts 13L and 13R are respectively placed on the half of the bearing holes 22a to 22d on the side of the lower housing 14L, and in this state, the upper housing 14U side of the bearing holes 22a to 22d is placed. The upper and lower housings 14U and 14L are joined to each other by aligning the halved portion of the upper and lower housings 14a to 16d with the journal portions 16a to 16d of the balancer shafts 13L and 13R. It will be rotatably accommodated in 14L. The thrust receiving surface 19 contacts the front and rear end surfaces of the bearing wall 23c in which the third bearing hole 22c is formed to receive the thrust force.
[0025]
As shown in FIG. 3, the upper and lower housings 14U and 14L are each provided with a plurality of bolts B2 inserted from above at appropriate positions, and third and fourth bearing holes 22c and 22d. It is fastened with three bolts B3 that pass through the walls 23c and 23d and are inserted from below. In particular, the parts of the bearing walls 23c and 23d on which radial acceleration due to the rotation of the counterweight portion 17 acts are loosened. It is considered that it becomes difficult to occur.
[0026]
A pump housing 24 provided with a trochoid lubricating oil pump (not shown) for pumping lubricating oil to various parts of the engine is bolted to the front end surface of the lower housing 14L. This lubricating oil pump (not shown) is provided at the shaft end of the right balancer shaft 13R, and when the right balancer shaft 13R rotates, an oil strainer 25 attached to the bottom wall of the lower housing 14L removes one of the lower housings 14L. The lubricating oil in the oil pan 5 is sucked through a tubular passage 26 provided in the side wall, and is pumped to various parts of the engine.
[0027]
The mounting portion 28 of the strainer cover 27 that holds the oil strainer 25 is integrally formed on the lower side of the two balancer shafts in the lower housing 14L, that is, on the lower position of the left balancer shaft 13L. The strainer cover mounting portion 28 has a substantially cylindrical shape, and is lower than the bolts provided between the two balancer shafts 13L and 13R among the bolts B3 for fastening the upper housing 14U and the lower housing 14L to each other. Bearing wall 23c provided with a center portion between the bolt provided on the outer side of the left balancer shaft 13L on the side and a half portion of the third bearing hole 22c in the middle portion in the front-rear direction of the lower housing 14L. The outer peripheral part is connected to. This enhances the rigidity of the bearing wall 23c that fastens the upper housing 14U and the lower housing 14L. Further, the tubular passage 26 integrally formed on one side wall of the lower housing 14 </ b> L is terminated at the joining surface of the pump housing 24.
[0028]
A fastening boss 30 for inserting one of the fastening bolts B <b> 1 with respect to the lower block 3 is provided at a position adjacent to the side of the end portion of the tubular passage 26, and the fastening rigidity of the balancing device 4 with respect to the lower block 3 is provided. It contributes to increase.
[0029]
As described above, the oil strainer 25 is mounted directly below the left balancer shaft 13L on the lower side of the two balancer shafts on the bottom wall of the lower housing 14L, and is close to the vertical plane passing through the center of the crankshaft 1. The center of the engine E is located directly below the center of gravity of the engine E. In this way, the suction port 29 of the strainer cover 27 is positioned at a position where the liquid level fluctuation is least at the bottom of the oil pan 5 without greatly extending the strainer cover mounting portion 28 downward. Therefore, even if the liquid level of the lubricating oil fluctuates due to longitudinal acceleration or centrifugal force during traveling, the oil suction does not deteriorate.
[0030]
As shown in FIGS. 4 and 5, axial oil passages extending substantially parallel to the axis of the balancer shaft are provided on the joint surfaces of the left and right walls 31 </ b> U and 31 </ b> L of the upper and lower housings 14 </ b> U and 14 </ b> L. 32 is recessed. The radial oil passages 33b to 33d branch from the axial oil passage 32 along the radial direction of the balancer shaft to reach the second to fourth bearing holes 22b to 22d. It is recessed in the joint surface of the 4th bearing walls 23b-23d.
[0031]
The front diameter of the upper housing 14U is such that the insertion holes H2 of the bolts B2 for fastening the upper and lower housings 14U and 14L are connected to each other through the inner peripheral surfaces of the left and right bearing holes 22b. A directional oil passage 33b is recessed. The third bearing wall 23c has a central diameter so that the female screw holes T3 into which the bolts B3 for fastening the upper and lower housings 14U and 14L are screwed together are connected via the inner peripheral surfaces of the left and right bearing holes 22c. The upper half 33c / U of the directional oil passage is recessed.
[0032]
In the third bearing wall 23c of the lower housing 14L, the insertion holes H3 of the bolts B3 for fastening the upper and lower housings 14U and 14L are connected to each other via the inner peripheral surfaces of the left and right bearing holes 22c. The lower half 33c / L of the radial oil passage is recessed. A rear radial oil passage 33d is recessed in the fourth bearing wall 23d through a part of the inner peripheral surface of the right bearing hole 22d through the inner peripheral surface of the left bearing hole 22d and the central bolt insertion hole H3. It is installed.
[0033]
These oil passages are formed in the casting process of the respective housings 14U and 14L so that their cross-sectional shapes are, for example, semicircular, and in particular, all parts of the axial oil passage 32 and the radial oil passages 33b to 33b. A part of 33d is formed into a substantially circular hole when the upper and lower housings 14U and 14L are joined.
[0034]
The engine oil supply provided in the lower block 3 when the upper housing 14U is joined to the lower surface of the lower block 3 is connected to the right end of the central radial oil passage 33c provided in the third bearing wall 23c of the upper housing 14U. A through hole 34 is formed along the cylinder axis so as to communicate with a passage (not shown), and the engine oil flowing into the central radial oil passage 33c from the lower block 3 is as shown in FIG. , A part of the oil hole 36 formed in the metal bearing 35 attached to the third bearing hole 22c is supplied to the sliding contact surface with the third journal portion 16c, and the rest flows into the axial oil passage 32. From there, the flow is divided into the radial oil passages 33b and 33d in the front and rear second bearing walls 23b and the fourth bearing wall 23d.
[0035]
The engine oil that has flowed into the front radial oil passage 33b passes through the second journal portion 16b from the oil hole formed in the metal bearing attached to the second bearing hole 22b on the upper housing 14U side in the same manner as described above. Is supplied to the first bearing hole 22a through a connecting passage 37 formed by a drill hole from the left bearing hole 22b / L of the second bearing wall 23b. The The remainder flows out from a drill hole 38 drilled from a joint surface with the pump housing 24 in the lower housing 14L so as to communicate with the terminal En of the front radial oil passage 33b, and is shown in the figure provided at the tip. Not supplied to chain tensioner devices etc.
[0036]
The engine oil that has flown into the rear radial oil passage 33d passes through a fourth journal portion from an oil hole formed in a metal bearing mounted in the fourth bearing hole 22d on the lower housing 14L side in the same manner as described above. It is supplied to the sliding contact surface with 16d.
[0037]
On the other hand, a return passage 41 for returning engine oil from the cylinder head side into the oil pan 5 is formed by casting in the center portion of the crankshaft 1 in the axial direction of the cylinder block 2 and the lower block 3 of the engine E. Has been. The return passage 41 opens to the lower surface of the lower block 3 and is connected to return passages (described in detail later) provided in the upper housing 14U and the lower housing 14L of the balancing device 4 joined to the lower surface of the lower block 3. Is done.
[0038]
As shown in FIG. 7 as well, the upper housing 14U has a vertical hole 42a penetrating vertically at the connecting portion between the left end of the third bearing wall 23c and the left side wall 31U, and an end at the lower end of the vertical hole 42a. A groove 42b having a semicircular cross-sectional shape is formed extending forward on the joint surface with the lower housing 14L.
[0039]
The vertical hole 42a is provided at a position connected to the lower end opening of the return passage 41 of the lower block 3, and this is positioned on a plane perpendicular to the axis of the balancer shaft and including the third bearing wall 23c. ing. That is, since the bearing wall provided with the bearing hole of the balancer shaft has a relatively high rigidity, a part of the return passage is provided in this portion, thereby suppressing a decrease in rigidity of the upper housing 14U.
[0040]
On the left side wall 31L of the lower housing 14L, a groove 42c having a semicircular cross-sectional shape that matches the groove 42b of the upper housing 14U is formed on the joint surface with the upper housing 14U. A vertical hole 42d is formed in the wall thickness of the left side wall 31L. The opening of the vertical hole 42d, that is, the oil discharge port 43 is formed at the lower end surface of the cylindrical portion 44 directly connected to the left side portion of the strainer cover mounting portion 28 formed integrally with the lower housing 14L, in other words, the oil strainer 25 It is provided so as to open at a position adjacent to the left side of the suction port 29 provided in the held strainer cover 27. In other words, the engine oil suction port 29 and the oil discharge port 43 are provided on substantially the same plane orthogonal to the axis of the balancer shaft, and the oil oil is discharged without being affected by changes in the vehicle posture or driving conditions. The mouth 43 is immersed below the oil level.
[0041]
The oil discharge port 43 is inwardly (on the balancer shaft side) of the insertion hole 45 (bolt B1) from the insertion hole 45 through which one of the bolts B1 for fastening the lower housing 14L to the cylinder block or the lower block is inserted. It is provided along the axis. The oil drain port 43 is provided between the fastening portion of the bolt B1, that is, the portion provided with the insertion hole 45 and the strainer cover mounting portion 28 on the bottom surface of the lower housing 14L, and the center thereof is a strainer cover having a perfectly circular outline. The center of the mounting portion 28 is shifted rearward with respect to the axial direction of the balancer shaft.
[0042]
By doing so, the space between the fastening portion of the bolt B1 and the strainer cover mounting portion 28 can be effectively utilized, so that the return path to the direction perpendicular to the axis of the balancer shaft, that is, to the outside of the lower housing 14L. The amount of overhang can be reduced, and the enlargement of the lower housing 14L can be suppressed. In addition, even if a return passage is provided, it is possible to prevent the lowering of rigidity in the lower housing 14L.
[0043]
The oil discharge port 43 is provided at a position offset backward in the axial direction of the balancer shaft with respect to the start end of the tubular passage 26 communicating between the oil strainer and the oil pump. Accordingly, the tubular passage 26 for supplying oil and the return passage for returning oil do not overlap with each other on a plane orthogonal to the axis of the balancer shaft, so that the configuration of the return passage is not complicated, and the lower housing 14L. The rigidity of the resin does not decrease.
[0044]
These vertical holes 42a and 42d and grooves 42b and 42c serve as a part of an oil return passage that bends in a crank shape and communicates in the balance device 4 vertically when the upper and lower housings 14U and 14L are joined. The engine oil that flows in from the cylinder head side through the return passage 41 provided in the lower block 3 flows into the oil pan 5 through the downstream portion 42 of the return passage. It is supposed to be returned.
[0045]
With the configuration described above, the vertical hole 42a of the upper housing 14U is provided at a position where it is connected to the opening of the return passage 41 of the lower block 3, and the opening end of the vertical hole 42d of the lower housing 14L, that is, the oil drainage. The mouth 43 can be arranged at an appropriate position, and in particular, by adjoining the suction port 29 of the strainer cover 27 provided at the position where the liquid level fluctuation is smallest at the bottom of the oil pan 5, Regardless of changes in operating conditions, the oil discharge port 43 can be provided at a position that always immerses below the oil level OL, so that air can be prevented from entering the engine oil in the oil pan 5. Moreover, since the cylindrical portion 44 is integrated with the strainer cover mounting portion 28, high rigidity is obtained, and its lower end surface extends to the same position as the strainer cover mounting portion 28. Therefore, the strainer cover mounting portion 28 and the cylindrical portion Since the 44 opening surfaces can be processed simultaneously, it is not necessary to increase the number of processing steps. Further, by extending the grooves 42b and 42c along the axis of the balancer shafts 13L and 13R, the amount of lateral protrusion of the upper and lower housings 14U and 14L is minimized.
[0046]
In addition to these, even if the engine oil flows in from the lower block 3 side, the force is reduced by hitting the groove 42c of the lower housing 14L, and the outflow speed from the oil discharge port 43 is reduced. In combination with the fact that the engine oil stored in the engine 5 is not agitated and the oil outlet 43 is always immersed below the oil level OL, the engine oil bubbles up due to air entrainment. Can be prevented from occurring.
[0047]
【The invention's effect】
As described above in detail, according to the first or second aspect of the present invention , the passage hole is provided in the housing of the balancer shaft located below the crankshaft, and the passage hole provided in the engine block (lower block) is formed in the passage hole. By connecting to the passage hole, the return passage from the cylinder head can be communicated to the lowermost part of the engine, so it is relatively easy to open below the oil level in the oil pan without requiring any special processing or separate parts. A return path for engine oil can be formed , and a great effect can be achieved in reducing the number of parts and the number of manufacturing steps of the engine itself.
[0048]
According to the invention of claim 3 , since a part of the return passage is extended along the joint surface between the upper and lower housings , the passage is arranged so that the oil discharge port is located at an arbitrary position. Since it can be routed relatively easily, the degree of freedom in setting the position of the oil outlet is increased, and the flow rate of the return oil is reduced by bending the passage to suppress the stirring of the engine oil in the oil pan. Effective on top.
[0049]
According to the invention of claim 4, the oil outlet of the return passage that opens to the bottom surface of the housing and the inlet of the oil strainer are provided so as to be in contact with substantially the same plane perpendicular to the axis of the balancer shaft. Therefore, it is basically possible to provide an oil drain port at a position close to the oil strainer suction port that always immerses below the oil level. It is possible to maintain an immersive state. In particular, if the portion where the oil discharge port is opened in the configuration of claim 4 is directly connected to the mounting portion of the oil strainer integrally formed on the bottom surface of the housing (claim 5), Not only is it not affected by the change, but it contributes to improving the rigidity of the part where the oil outlet opens.
[0050]
According to the sixth aspect of the present invention, since a part of the return passage is provided in the vicinity of the relatively rigid bearing portion, the passage hole can be formed without causing a decrease in the rigidity of the housing.
[0051]
Further, according to the invention of claim 7 , along the axis of the bolt insertion hole at a position adjacent to the bolt insertion hole inside the bolt insertion hole for fastening the housing to a portion of the engine block located below the crankshaft. Since a part of the return passage is extended, an increase in the size of the housing due to the provision of the return passage can be avoided.
[Brief description of the drawings]
FIG. 1 is a front sectional view showing a part of a main part of an engine to which the present invention is applied. FIG. 2 is a partial side sectional view taken along line II-II in FIG. FIG. 4 is a bottom view of the upper housing of the balancing device. FIG. 5 is a top view of the lower housing of the balancing device. FIG. 6 is a partial sectional view of the third bearing wall. 2 is a partial cross-sectional view taken along line VII-VII in FIG.
DESCRIPTION OF SYMBOLS 1 Crankshaft 4 Balancing device 5 Oil pan 13L * 13R Balancer shaft 14U Upper housing 14L Lower housing 22c Bearing hole 28 Strainer cover attaching part 42 Return part downstream part 42a * 42d Vertical hole 42b * 42c Groove 43 Oil drain port 44 Cylindrical shape Part 45 Bolt insertion hole

Claims (7)

An engine oil return passage for returning engine oil from a cylinder head side to an oil pan in an engine provided with a housing that rotatably receives a balancer shaft below the crankshaft ;
The housing is joined to a portion of the engine block located below the crankshaft,
The return passage is engine oil, characterized in that those having internally provided passageways hole and a formed by connecting together portions to the an opening for the passage holes housing the joint surface of the housing in the engine block Return passage. An engine oil return passage for returning engine oil from a cylinder head side to an oil pan in an engine provided with a housing that rotatably receives a balancer shaft below the crankshaft;
The housing is joined to a portion located below the crankshaft in the lower block joined to the lower surface of the cylinder block,
The return passage is characterized as to Rue Njin'oiru that those having installed inside passageways hole and a formed by connecting together portions to said housing and passage holes opening on the joint surface of the housing in the Lower block Return passage. An engine oil return passage for returning engine oil from a cylinder head side to an oil pan in an engine provided with a housing that rotatably receives a balancer shaft below the crankshaft;
The housing is composed of an upper housing and a lower housing which are divided into upper and lower parts and joined to each other, and at least a part of the return passage extends along a joining surface between the two housings. return passage of the Rue be Njin'oiru. An engine oil return passage for returning engine oil from a cylinder head side to an oil pan in an engine provided with a housing that rotatably receives a balancer shaft below the crankshaft;
An oil return passage for engine oil, wherein an oil discharge port of the return passage and an intake port of an oil strainer are provided on a bottom surface of the housing so as to be in contact with substantially the same plane perpendicular to the axis of the balancer shaft . 5. The engine oil return path according to claim 4 , wherein a portion where the oil discharge port is opened is directly connected to a mounting portion of an oil strainer integrally formed on a bottom surface of the housing . At least a portion of the return passage is bearing holes as the balancer shaft, and according to any one of claims 1 to 5, characterized in that said those provided on a plane perpendicular to the axis of the balancer shaft Engine oil return passage. The housing is fastened with a bolt to a portion of the engine block located below the crankshaft, and at least a part of the return passage is inside the bolt insertion hole provided in the housing. The return passage for engine oil according to any one of claims 1 to 6, wherein the return passage for engine oil extends along the axis of the bolt insertion hole at a position adjacent to the insertion hole .

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