JP2014228020A - Balancer body of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a balancer body of an internal combustion engine capable of reducing rotational resistance of a crank shaft by suppressing contact between a rotor and oil in a crank chamber.SOLUTION: A balancer body 22 is configured to include: a body upper 22U having an upper wall 41 assuming a semi-circular arc shape protruding downward on a cross section orthogonal to a crankshaft 11 and partitioning the inside of a crank case 9 into a crank chamber 8 and an oil reservoir 35; a body lower 22L fastened at a lower part of the body upper 22U and pivotally supporting a balancer shaft 21 in cooperation with the body upper 22U; an oil discharge port 46 formed at the lowermost end on the upper wall 41 of the body upper 22U so as to open facing a swirl flow in the crank chamber 8; and an oil discharge passage 48 formed extending to the lower part of the upper wall 41 in the body upper 22U so as to guide the oil discharged from the oil discharge port 46 to the oil reservoir 35.

Description

  The present invention relates to a balancer body that houses a pair of balancer shafts that are provided at the lower part of a crankcase of an internal combustion engine so as to rotate in directions opposite to each other.

  In an internal combustion engine, a balancer shaft having a balancer weight for canceling vibrations generated by a reciprocating motion of a piston and a connecting rod is disposed below the crankshaft, and the rotation of the crankshaft is performed via a chain / sprocket mechanism. There may be a balancer device that is transmitted to the shaft to rotate the balancer shaft.

  In such a balancer device, there is a case where the balancer shaft is partially immersed in the oil surface stored in the oil pan in order to reduce the height dimension of the internal combustion engine. Therefore, not only the air bubbles are mixed into the oil and the lubrication performance is deteriorated, but also the agitation of the oil increases the rotational resistance of the balancer shaft, thereby deteriorating the fuel efficiency.

  Therefore, in order to prevent the oil in the oil pan and the oil flowing down from the cylinder block from coming into contact with the balancer shaft, a balancer body (casing) is provided so as to cover the balancer shaft, and the balancer shaft that rotates the oil in the balancer body. Has proposed that the oil outlet for discharging to the outside is formed at a position above the oil level in the oil pan in the balancer body (see Patent Document 1).

  In Patent Document 1, the upper wall of the balancer body is wider than the pair of balancer shafts, so that oil flowing down from the cylinder block does not contact the balancer shaft. In addition, since the balancer body of Patent Document 1 also functions as a baffle plate, it is possible to suppress the oil level from violating to some extent without increasing the overall height of the internal combustion engine because the baffle plate is separately provided.

Japanese Utility Model Publication No. 62-28937

  However, in the balancer body of Patent Document 1, the upper walls that cover the pair of balancer shafts from above are curved downward, and the oil accumulated on the upper walls is not limited to the crankshaft or the large end of the connecting rod. There is a risk of contact with the rotating body. When the rotating body is constantly in contact with oil, the oil becomes hot and the lubrication performance is lowered, or the rotational resistance of the crankshaft is increased by the agitation of the oil, which adversely affects the performance of the internal combustion engine. Further, since the splashed oil flying in the crank chamber cannot be efficiently guided to the oil reservoir, the opportunity for contact between the oil mist staying in the crank chamber and the rotating body increases, and this also increases the rotational resistance of the crankshaft.

  The present invention has been made in view of such a background, and it is possible to reduce the rotational resistance of the crankshaft by suppressing the contact between the rotating body and the oil in the crank chamber without increasing the overall height of the internal combustion engine. An object of the present invention is to provide a balancer body for an internal combustion engine.

  In order to solve such a problem, according to one aspect of the present invention, the lower part in the crankcase (9) of the internal combustion engine (1) rotates parallel to the crankshaft (11) and in a direction opposite to each other. A balancer body (22) that accommodates a pair of balancer shafts (21F, 21B) provided in the above-described manner, and has a semicircular arc shape that protrudes downward in a cross section perpendicular to the crankshaft (11), and has a crankcase (9 ) Are fastened to a body upper (22U) having an upper wall (41) that partitions the crank chamber (8) and an oil sump (35) into the lower part of the body upper (22U). ) And the balancer chamber (B) for supporting the pair of balancer shafts (21) and for accommodating the balancer weight (21a). (22L) and in a state in which the internal combustion engine (1) is mounted on a vehicle on a horizontal road surface, the swirl flow of the crank chamber (8) at the lowest end of the upper wall (41) of the body upper (22U). An oil discharge port (46) formed so as to be opposed to the oil discharge port, and the oil discharged from the oil discharge port (46) to guide the oil to the oil reservoir (35). The oil discharge passage (48) is formed so as to extend below the upper wall (41).

  According to this configuration, the upper wall of the body upper also functions as a baffle plate, so that the oil immersion depth of the balancer body can be reduced to shorten the overall height of the internal combustion engine. In addition, the oil that splashes in the swirl flow in the crank chamber can be efficiently recovered from the oil discharge port formed at the lower end of the upper wall and guided to the oil sump through the oil discharge passage, so the crankshaft and connecting rod The oil agitation loss of the rotating body and the oil agitation loss of the balancer shaft can be suppressed. Furthermore, since the upper wall of the body upper has a semicircular arc shape, the splashed oil can be collected from the oil discharge port without disturbing the swirling flow in the crank chamber, so that the amount of oil mist floating in the crank chamber can be reduced. This can also reduce the stirring resistance due to the contact between the rotating body and the oil in the crank chamber.

  Further, according to one aspect of the present invention, in order to discharge the oil in the balancer chamber (B) to the outside, the body upper (22U) is below the upper wall (41) and on the horizontal road surface. The balancer chamber (B) and the oil sump (35) are communicated with each other at a position higher than the oil level of the oil sump (35) in an operating state of the internal combustion engine (1) mounted on the vehicle. The balancer oil discharge port (43) can be further provided.

  According to this configuration, since the balancer oil discharge port is formed at a position below the upper wall and higher than the oil level of the oil reservoir, the balancer body inside the balancer body is scattered radially outward by the pair of balancer shafts. The oil can be discharged into the atmosphere of the oil reservoir without being exposed above the upper wall on which the crank swirl flows (without being affected by the swirl flow). Therefore, the discharged oil can be prevented from flowing back into the crank chamber, and the oil stirring loss due to the rotating body can be reduced. Since the balancer oil discharge port is formed at a position higher than the oil level of the oil reservoir, the oil in the oil reservoir is prevented from entering the balancer chamber from the balancer oil discharge port.

  According to one aspect of the present invention, the internal combustion engine (1) is an in-line four cylinder, and each balancer shaft (21) is a pair of body upper (22U) and body lower (22L). It has a single balancer weight (21a) disposed between the bearings (24, 25), and the body upper (22U) and the body lower (22L) are the internal combustion engine in the crankshaft (11). Each balancer shaft (21) is placed in a state where the balancer weight (21a) is arranged at a position corresponding to the second throw (second throw chamber 17) counted from the side opposite to the flywheel (F) of (1). It can be set as the structure supported.

  According to this configuration, the pair of bearings configured by the balancer body can be easily formed by drilling the through holes by bearing processing. In addition, each balancer shaft has a single balancer weight, and oil intrusion from the bearing hole into the balancer chamber can be prevented by the oil film of the radial slide bearing, so that the axial length of the balancer body can be shortened. Furthermore, the balancer weight is not offset from the center of the third journal bearing, which is the center in the crankshaft direction of the in-line four-cylinder internal combustion engine, but at a position offset from the center corresponding to the second throw counted from the side opposite to the flywheel. By disposing, a wide shallow bottom can be formed in the oil pan. Therefore, it is possible to secure a wider space for allowing the exhaust pipe to pass under the oil pan, which is a problem in a horizontally mounted internal combustion engine with front exhaust.

  Further, according to one aspect of the present invention, the balancer oil discharge port (43) corresponds to a suction port (36a) of an oil strainer (36) provided in the oil reservoir (35) with respect to a crankshaft direction. It can be set as the structure arrange | positioned.

  The intake port of the oil strainer is usually provided at a position where the oil level rises the least when the oil level is inclined such as when the vehicle is turning. For this reason, the balancer oil discharge port is provided at a position corresponding to the oil strainer suction port in the crankshaft direction, so that the oil can be retained even when the oil surface of the oil sump is inclined in the crankshaft direction when the vehicle is turning. Since the oil does not easily reach the balancer oil discharge port and oil can be prevented from entering the balancer chamber, loss of oil agitation due to the balancer shaft can be prevented.

  Further, according to one aspect of the present invention, the internal combustion engine (1) is mounted on a vehicle in a posture in which the crankshaft (11) is horizontal and the cylinder axis is inclined, whereby the pair of balancer shafts ( 21) are arranged at different heights, and the balancer oil discharge ports (43) are formed in a pair corresponding to the pair of balancer shafts (21F, 21B) and correspond to the lower balancer shaft (21B). The balancer oil discharge port (43B) to be arranged may be arranged above the suction port (36a) of the oil strainer (36).

  According to this configuration, not only in the crankshaft direction but also when the oil level is inclined in a direction perpendicular to the crankshaft direction on a horizontal plane, the oil is difficult to enter from the lower balancer oil discharge port into the balancer chamber, Oil stirring loss due to the balancer shaft during turning and acceleration / deceleration of the vehicle can be prevented more reliably. The balancer oil discharge port corresponding to the upper balancer shaft is disposed at a position offset from the suction port of the oil strainer, but can be disposed at a position higher than the lower balancer oil discharge port. , There is little worry about oil intrusion.

  Thus, according to the present invention, the balancer body of the internal combustion engine that can reduce the rotational resistance of the crankshaft by suppressing the contact between the rotating body and the oil in the crank chamber without increasing the overall height of the internal combustion engine. Can be provided.

Sectional view of an internal combustion engine according to the present invention II-II sectional view in FIG. III-III sectional view in FIG.

  Hereinafter, an embodiment in which a balancer body 22 according to the present invention is applied to an internal combustion engine 1 of an automobile will be described in detail with reference to the drawings. Each figure shows a state of being mounted on an automobile on a horizontal road surface, and the description will be made with reference to the direction indicated by the arrow in the figure. FIG. 1 shows a cross section taken along line II in FIG.

  As shown in FIGS. 1 and 2, the internal combustion engine 1 is a 4-stroke in-line 4-cylinder reciprocating internal combustion engine. The internal combustion engine 1 includes a cylinder block 2, a cylinder head 3 joined to the upper part of the cylinder block 2, a head cover 4 joined to the upper part of the cylinder head 3, and a lower block 5 joined to the lower part of the cylinder block 2. And an oil pan 6 joined to the lower part of the lower block 5.

  The upper part of the cylinder block 2 forms four cylinder bores 7 arranged in a row in parallel with each other in the left-right direction. The lower part of the cylinder block 2, the lower block 5 and the oil pan 6 form a crank chamber 8. Case 9 is configured. A piston 10 is slidably received in each cylinder bore 7, and a crankshaft 11 extending horizontally in the left-right direction is rotatably received in the crank chamber 8. The internal combustion engine 1 is mounted on a vehicle in a state where the cylinder bores 7 are arrayed in the left-right direction and the upper side of the center axis of each cylinder bore 7 is tilted rearward and tilted backward. In the present embodiment, the internal combustion engine 1 is a front exhaust in which an unillustrated intake pipe is connected to the rear part and an exhaust pipe EP (FIG. 1) is connected to the front part.

  The cylinder block 2 is integrally formed with an upper half portion 12U of the journal bearing 12 in which a half bearing surface is formed, and the lower block 5 is integrally formed with a bearing cap 12L constituting the lower half portion of the journal bearing 12. Is formed. When the lower block 5 is joined to the lower surface of the cylinder block 2, the upper half 12U of the journal bearing 12 and the bearing cap 12L constitute a journal bearing 12 that rotatably supports the journal 13 of the crankshaft 11. The journal bearings 12 are formed at a total of five places, three places between the cylinder bores 7 adjacent to each other and two places outside the cylinder bores 7 at both left and right ends.

  The crankshaft 11 includes five journals 13 formed at positions corresponding to the five journal bearings 12, four crankpins 14 (FIG. 2) provided between the adjacent journals 13, and both ends of the crankpin 14. The web 15 is connected to the adjacent journal 13, and the counter weight 16 is provided on the web 15 on the side opposite to the crank pin 14. In the present embodiment, a pair of webs 15 and one crankpin 14 between adjacent journals 13 constitute a throw (crank throw). The crankshaft 11 is rotatably supported by the crankcase 9 while being received in the crank chamber 8, by journaling the journal 13 with the journal bearing 12.

  A flywheel F is integrally provided at the right end of the crankshaft 11, and the rotation of the crankshaft 11 is transmitted to the transmission via a clutch disk (not shown) arranged to face the flywheel F.

  Hereinafter, each journal bearing 12 is defined as first, second, third, fourth, and fifth from the left side (the side opposite to the flywheel F). Further, a crank chamber portion corresponding to a throw between a pair of journals 13 sandwiching the crank pin 14 in the crankshaft 11, that is, between adjacent journal bearings 12 is referred to as a throw chamber 17, and in this embodiment 4 corresponding to the cylinder bore 7. The two throw chambers 17 are first, second, third, and fourth from the left side. As described above, in the present embodiment, since the internal combustion engine 1 is an in-line cylinder, one crank pin 14 corresponding to one cylinder bore 7 is disposed in each slow chamber 17, but the internal combustion engine 1 is a V-type cylinder. In the case of a horizontally opposed cylinder or the like, two crank pins 14 corresponding to the pair of cylinder bores 7 are arranged in each slow chamber 17.

  Each piston 10 has a piston pin 10a (FIG. 2), and a small end portion 18a of a connecting rod 18 is connected to the piston pin 10a. The large end portion 18 b of the connecting rod 18 is connected to the crank pin 14 of the crankshaft 11. As a result, the piston 10 and the crankshaft 11 are connected to each other via the connecting rod 18, and the reciprocating motion of the piston 10 is converted into the rotational motion of the crankshaft 11. The crankshaft 11 rotates clockwise as indicated by an arrow in FIG. Therefore, during the operation of the internal combustion engine 1, the same clockwise swirling flow as that of the crankshaft 11 is generated in the crank chamber 8.

  As shown in FIG. 2, the large end portion 18b of each connecting rod 18 constitutes a rod side member 18c constituting one of the half bearings and the other half bearing, and the rod is constituted by two bolts 18d. The connecting rod cap 18e is fastened to the side member 18c. In the connecting rod cap 18e, a pair of bolt bosses are formed in front and rear of the crankpin 14 in a direction perpendicular to the joint surface with the rod side member 18c. The bolt boss and the bolt 18d that fastens the bolt protrude outward with respect to the semicircular cap base portion, whereby the large end portion 18b of the connecting rod 18 has a substantially rectangular shape. Therefore, the outer edge of the trajectory drawn by the connecting rod 18 (hereinafter referred to as the outermost peripheral rotation trajectory 19) has a shape as shown by a broken line in FIG. 2, and the outermost peripheral rotation trajectory 19 (shown by the broken line) drawn by the large end 18b. The lower part of the trajectory has an arc shape around the rotation center of the crankshaft 11 (hereinafter referred to as the crankshaft rotation center 11X), but is not a complete arc.

  In the present embodiment, the internal combustion engine 1 is configured such that the crankshaft rotation center 11X is positioned on a plane including the central axis of the cylinder bore 7 for the sake of simplicity of explanation. Like the offset cylinder, the crankshaft rotation center 11X may be displaced from the center of the substantially circular crank chamber 8.

  A balancer device 20 for reducing secondary vibration of the internal combustion engine 1 generated due to the reciprocating motion of the piston 10 and the connecting rod 18 is attached to the lower part of the first to third journal bearings 12. The balancer device 20 is provided in a semi-oil-immersed state in which a part of the oil is accumulated in the oil pan 6 so as to rotate in the oil pan 6 in parallel to the crankshaft 11 and in mutually opposite directions. A pair of front and rear balancer shafts 21 (21F, 21B) that are provided and have substantially the same shape, and a balancer body 22 that supports the balancer shaft 21 and that defines a balancer chamber B that accommodates the balancer weight 21a. ing.

  In addition, since the internal combustion engine 1 is mounted on the automobile in a rearward inclined posture in which the crankshaft 11 is leveled and the central axis of the cylinder bore 7 is inclined rearward, the rear balancer shaft 22B is more than the front balancer shaft 22F. The balancer body 22 is also arranged in an inclined state in which the rear part is lower than the front part. The balancer body 22 includes a body upper 22U integrated with the lower block 5, and a body lower 22L fastened to the lower portion of the body upper 22U. The body upper 22U may be formed integrally with the lower block 5, or may be formed as a separate body and integrally joined to the lower block 5.

  The balancer body 22 is disposed below the first journal bearing 12, the first bearing portion 23 disposed below the second journal bearing 12, the second bearing portion 24 disposed below the second journal bearing 12, and the third journal bearing 12. The third bearing portion 25, the first cover portion 26 that defines the gear chamber G between the first bearing portion 23 and the second bearing portion 24, the second bearing portion 24, and the third bearing portion 25, And a second cover portion 27 that defines a balancer chamber B that accommodates the balancer weight 21a. Each of the bearing portions 23 to 25 is provided with an oil supply groove 29 communicating with an oil supply groove 28 formed on the inner peripheral surface (bearing surface) of the corresponding journal bearing 12, and is supplied from the oil supply groove 29. In addition, a fluid lubricated bearing that supports the balancer shaft 21 by the wedge action and squeeze action of the lubricating oil is configured. The oil supplied to each of the bearing portions 23 to 25 leaks to the outside through the bearing gap and is discharged to the gear chamber G, the balancer chamber B, and the like. The first cover part 26 and the second cover part 27 are disposed outside the lower part of the outermost peripheral rotation locus 19 in the corresponding slow chambers 17.

  Both balancer shafts 21 are pivotally supported at three locations by a first bearing portion 23, a second bearing portion 24 and a third bearing portion 25. The front balancer shaft 21 </ b> F has a small sprocket 31 at the left end, and an endless link chain 33 is stretched between the small sprocket 31 and a large sprocket 32 fixed to the left end of the crankshaft 11. 11 is transmitted and rotates in the same direction as the crankshaft 11 at twice the rotational speed of the crankshaft 11. Both balancer shafts 21 have helical gears 34 disposed in the first cover portion 26 corresponding to the first throw chamber 17 and meshing with each other, and thereby rotate at the same rotational speed in opposite directions.

  Both balancer shafts 21 have balancer weights 21 a in the first cover portion 26 corresponding to the second throw chamber 17, and rotate at twice the rotational speed of the crankshaft 11, whereby inertia in the cylinder axis direction. A secondary vibration of the internal combustion engine 1 is reduced by generating a force. Here, the balancer weight 21 a has an axial length substantially equal to the separation distance between the second bearing portion 24 and the third bearing portion 25, and its axial end surface defines the axial position of each balancer shaft 21. The specified thrust bearing surface.

  In this way, each balancer shaft 21 has a single balancer weight 21a disposed between the second bearing portion 24 and the third bearing portion 25, so that both holes can be formed by drilling through holes by bearing processing. The bearing portions 24 and 25 can be easily formed. Further, since the oil penetration of the radial slide bearing prevents oil from entering the balancer chamber B in the bearing holes of the second bearing portion 24 and the third bearing portion 25, the axial length of the balancer body 22 can be shortened. It has become.

  As shown in FIG. 1, in the oil pan 6 (hereinafter referred to as an oil sump 35), oil (not shown) that pumps the stored oil to a friction part of the internal combustion engine 1 such as a crankshaft 11 or a camshaft. The pump is located at the left end. An oil strainer 36 having a suction port 36 a is attached to the oil pump near the bottom of the oil reservoir 35. The oil pan 6 has a shallow bottom on the right side where the oil pump is not disposed in order to secure a space through which the exhaust pipe EP passes. For this reason, the suction port 36a of the oil strainer 36 is located below the second throw chamber 17 where the oil surface at the limit turning (designed maximum inclined oil surface OL) indicated by an imaginary line in FIG. 1 intersects, that is, below the balancer device 20. Has been placed.

  As shown in FIG. 2, in the second cover portion 27 disposed on the lower outer side of the outermost peripheral rotation locus 19 in the second throw chamber 17, the body upper 22 </ b> U has an upper wall 41 that exhibits a downwardly convex semicircular arc shape. And a pair of front and rear side walls 42 (42F, 42B) along the rotation trajectory of the pair of balancer shafts 21, and during operation of the internal combustion engine 1, at least the upper wall 41 and the upper portions of both side walls 42 are oil. It is arranged at a position higher than the oil level of the reservoir 35. The upper wall 41 and the side walls 42F and 42B are separated from each other, and the space formed between them connects the balancer chamber B and the oil reservoir 35 at a position higher than the oil level of the oil reservoir 35. It functions as a balancer oil discharge port 43 for discharging the oil in the balancer chamber B to the outside (oil sump 35).

  Since the balancer body 22 is inclined, the front balancer oil discharge port 43F is formed at a position higher than the rear balancer oil discharge port 43B. On the other hand, the balancer oil discharge port 43B formed at a low position is an oil strainer disposed below the position where the oil surface (designed maximum inclined oil surface OL) at the time of limit acceleration / deceleration indicated by an imaginary line in FIG. 2 intersects. The two balancer oil discharge ports 43F and 43B are disposed at a position higher than the design maximum inclined oil surface OL.

  Since the balancer oil discharge port 43 is formed at a position higher than the oil level of the oil reservoir 35 in this way, the oil in the oil reservoir 35 is prevented from entering the balancer chamber B from the balancer oil discharge port 43. The Further, since the balancer weight 21 a and the balancer oil discharge port 43 are provided at the axial position corresponding to the second throw chamber 17, the oil is more oily than the case where the third journal bearing 12 is used as the center. The shallow bottom portion of the pan 6 can be formed widely, and it is easy to secure a space for allowing the exhaust pipe EP to pass under the oil pan 6.

  Further, since the balancer oil discharge port 43 is formed at a position corresponding to the suction port 36a of the oil strainer 36 with respect to the crankshaft direction, the oil reservoir 35 is oiled even when the oil level of the oil sump 35 is inclined during the turning operation of the automobile. However, since the oil does not easily reach the balancer oil discharge port 43 and the oil does not enter the balancer chamber B, an increase in oil agitation loss due to the balancer shaft 21 is prevented. In addition, since the rear balancer oil discharge port 43B is disposed above the suction port 36a of the oil strainer 36, the oil level of the oil sump 35 can be inclined during acceleration / deceleration of the vehicle or traveling on a sloping road. The oil does not enter the balancer chamber B from the lower balancer oil discharge port 43B.

  The balancer oil discharge port 43 has a length substantially equal to that of the balancer weight 21a in the axial direction of the balancer shaft 21, and the oil in the balancer chamber B that is swept up by the balancer weight 21a and scattered radially outward is efficiently used. It can be discharged well.

  The upper wall 41 of the body upper 22U has a radius larger than the radius of the arc of the circle C passing through the point farthest from the crankshaft rotation center 11X in the outermost peripheral rotation locus 19 drawn by the large end portion 18b of the connecting rod 18. It has an arc-shaped inner surface, and the circumferential end of the inner surface is smoothly connected to the inner surface of the lower block 5. As a result, the space defined by the crankcase 9 is partitioned into the crank chamber 8 and the oil sump 35, and the crank chamber 8 has a circular cross section and the swirl flow generated in the crank chamber 8 may be disturbed. The rotation resistance of the crankshaft 11 is reduced. Further, since the upper wall 41 of the body upper 22U of the balancer device 20 functions as a baffle plate, the oil immersion depth of the balancer body 22 becomes shallow, and the overall height of the internal combustion engine 1 can be shortened. In addition, the circumferential direction edge part of the inner surface of the upper wall 41 may be smoothly connected to the inner surface of the lower block 5 expanding the cylindrical radius.

  The upper wall 41 does not need to be a plate having a uniform thickness, for example, a combination of a cast part integrally formed with the lower block 5 and a sheet metal molded product made of a steel plate joined thereto, It may be a cast product, a steel plate molded product, a resin molded product, or a combination thereof formed separately from the lower block 5 and joined to the lower block 5 by any joining method such as welding, adhesion, or bolting. .

  The upper wall 41 of the body upper 22U has an upstream upper wall portion 44 on the upstream side (right side in FIG. 2) and a downstream side in the crank rotation direction with respect to the lowermost portion intersecting the vertical plane VP passing through the crankshaft rotation center 11X. And a downstream upper wall portion 45 on the left side).

  The inner surface of the upstream side upper wall portion 44 extends downward while curving from the base end on the lower block 5 side (right side of the paper) toward the tip through the outside of the circle C, and the tip is the lowest bottom in the vertical direction. The arc shape is such that On the other hand, the downstream-side upper wall portion 45 has an outer surface having a smaller radius than the inner surface of the upstream-side upper wall portion 44 at the lowermost portion. As a result, an oil discharge port 46 is formed at the lowermost portion of the upper wall 41 so as to open facing the crank rotation direction (swirl flow). Further, the inner surface of the downstream side upper wall portion 45 is formed so as to have only an upward gradient from the tip toward the downstream side in the crank rotation direction.

  Therefore, the splashed oil scattered in the crank chamber 8 is effectively discharged from the oil discharge port 46 to the oil reservoir 35, and the oil stirring loss of the rotating body including the crankshaft 11 and the connecting rod 18 is reduced. The rotation resistance of the crankshaft 11 is also reduced by suppressing the turbulence and reducing the amount of oil mist floating in the crank chamber 8. Further, since the inner surface of the downstream upper wall portion 45 is made only an upward gradient from the tip toward the downstream side in the crank rotation direction, the oil is discharged from the oil discharge port 46 without accumulating on the upper surface of the inner surface of the downstream upper wall portion 45. Therefore, no oil remains when the oil is changed during maintenance.

  An extension portion 47 that extends downstream in the crank rotation direction is formed integrally with the lowermost portion of the upstream upper wall portion 44 that forms the lower edge of the oil discharge port 46, below the downstream upper wall portion 45. . The extending portion 47 is inclined downward toward the tip, and extends further to the rear than the balancer oil discharge port 43. Thereby, the oil in the crank chamber 8 does not remain, and the oil discharged from the oil discharge port 46 does not flow into the balancer chamber B from the balancer oil discharge port 43. Further, the downstream side in the crank rotation direction of the upper wall 41 of the body upper 22U has a labyrinth-shaped two-tank structure, and the oil level is violated during turning and the oil flows into the upper wall 41, thereby increasing the crank stirring resistance. In addition to being prevented, the hot blow-by gas is prevented from coming into direct contact with the oil stored in the oil reservoir 35.

  Note that the oil discharged from the oil discharge port 46 is assumed to be discharged in a state where it is blown off on the swirl flow in the crank chamber 8 during operation of the internal combustion engine 1, so that the extension 47 It is not always necessary to extend the tip of the rear end beyond the balancer oil outlet 43.

  As described above, the extension 47 of the upstream upper wall 44 extends below the downstream upper wall 45, so that the space formed to extend below the upper wall 41 becomes oil drainage. It functions as an oil discharge passage 48 that guides the oil discharged from the outlet 46 to the oil reservoir 35. By forming such an oil discharge passage 48, an increase in the amount of oil in the balancer chamber B due to the inflow of oil discharged from the oil discharge port 46 is prevented, so that oil agitation loss due to the balancer shaft 21 is reduced. .

  The oil in the balancer chamber B swept up by the balancer shaft 21 is formed by the extension 47 of the upstream upper wall 44 and the downstream upper wall 45 formed above the balancer oil discharge port 43. However, since the oil is discharged into the atmosphere of the oil reservoir 35 without being affected by the swirling flow due to the exposure to the crank chamber 8, the oil discharged from the balancer chamber B is prevented from flowing back into the crank chamber 8 and rotated. Oil stirring loss by the body is reduced.

  Although illustration is omitted, the first cover portion 26 provided at a position corresponding to the first throw chamber 17 is also configured in the same manner as the second cover portion 27. In the first cover portion 26, the oil in the gear chamber G is lifted up by the pair of helical gears 34 and discharged to the outside (oil sump 35) from the discharge port formed in the body upper 22U.

  As shown in FIG. 1 and FIG. 3, in the portion corresponding to the third throw chamber 17 and the fourth throw chamber 17 where the balancer device 20 is not provided, the body upper 22U A baffle plate 50 having a shape similar to that of the wall 41 (FIG. 2) is provided, and the space defined by the crankcase 9 is partitioned into a crank chamber 8 and an oil sump 35 by the baffle plate 50. . In the present embodiment, the baffle plate 50 is a sheet metal molded product of a steel plate, and is joined to the lower block 5 by welding or the like.

  The baffle plate 50 does not need to be made of a plate member having a uniform thickness. For example, the baffle plate 50 may be a combination of a cast part integrally formed with the lower block 5 and a sheet metal molded product made of a steel plate joined thereto. The casting is formed separately from the lower block 5 and is joined to the lower block 5 by any joining method such as welding, bonding, or bolting, or a steel molded product, a resin molded product, or a combination thereof. Good. Further, if the baffle plate 50 is disposed in the space defined by the crankcase 9, it is not necessary to be joined to the lower block 5, but it is joined to the oil pan 6, or the lower block 5 and the oil pan 6 are connected to each other. It may be pinched.

  The baffle plate 50 has a semi-cylindrical shape that protrudes downward along the outermost peripheral rotation locus 19 drawn by the large end portion 18 b at a position corresponding to the third and fourth throw chambers 17. In other words, the baffle plate 50 includes two semi-cylindrical portions 51 that are provided at positions corresponding to the third and fourth throw chambers 17 and have a semi-cylindrical shape. Each semi-cylindrical portion 51 has a shape corresponding to the upper wall 41 of the body upper 22U shown in FIG. 2 and performs the same function. Here, the corresponding portion of the upper wall 41 corresponds to the corresponding portion or the like. The detailed explanation is omitted.

  In this way, all the slow chambers 17 are formed in a circular shape, and the oil discharge port 46 that opens so as to face the swirling flow is formed at the lowermost portion thereof, so that the rotational resistance of the crankshaft 11 is effectively reduced. To reduce.

  As shown in FIG. 1, the oil discharge port 46 is formed over the entire width of the throw chamber 17 in the second and third throw chambers 17, while the width of the throw chamber 17 in the first and fourth throw chambers 17. It is narrower than that of the second and third throw chambers 17, and is formed at a position closer to the adjacent second throw chamber 17 and third throw chamber 17, respectively. As a result, all the oil discharge ports 46 can be arranged at a position higher than the designed maximum inclined oil level OL, and even if the oil level of the oil sump 35 is inclined during turning, the oil in the oil sump 35 is Does not flow into the crank chamber 8 from the oil discharge port 46, so that crank stirring loss is prevented.

  The area of these oil discharge ports 46 may be set to a size that allows all of the oil falling in the corresponding slow chamber 17 to be discharged according to the amount of oil falling in each slow chamber 17.

  Although the description of the specific embodiment is finished as described above, the present invention is not limited to the above embodiment and can be widely modified. For example, in the above-described embodiment, the internal combustion engine 1 has been described for an automobile as an example, but the present invention can be widely applied to a railway vehicle or the like. Further, the specific configuration, arrangement, quantity, angle, etc. of each part of the balancer body 22 can be changed as long as they do not depart from the spirit of the present invention. On the other hand, all the components of the balancer body 22 shown in the above embodiment are not necessarily essential, and can be appropriately selected.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 8 Crank chamber 9 Crank case 11 Crankshaft 17 Throw chamber 21 (21F, 21B) Balancer shaft 21a Balancer weight 22 Balancer body 22U Body upper 22L Body lower 24 2nd bearing part (bearing)
25 Third bearing (bearing)
35 Oil reservoir 36 Oil strainer 36a Suction port 41 Upper wall 43 (43F, 42B) Balancer oil discharge port 46 Oil discharge port 48 Oil discharge passage B Balancer chamber F Flywheel

Claims (5)

A balancer body that houses a pair of balancer shafts provided in a lower part of a crankcase of an internal combustion engine so as to rotate in a direction opposite to each other in parallel to the crankshaft,
A body upper having an upper wall that presents a semicircular arc shape projecting downward in a cross section perpendicular to the crankshaft and divides the inside of the crankcase into a crank chamber and an oil sump;
A body lower that is fastened to a lower portion of the body upper and that supports the pair of balancer shafts in cooperation with the body upper and defines a balancer chamber for accommodating a balancer weight;
In a state where the internal combustion engine is mounted on a vehicle on a horizontal road surface, an oil discharge port formed to open at the lowermost end of the upper wall of the body upper so as to face the swirling flow of the crank chamber;
A balancer body comprising an oil discharge passage formed to extend below the upper wall of the body upper so as to guide oil discharged from the oil discharge port to the oil reservoir.   In order to discharge the oil in the balancer chamber to the outside, it is below the upper wall of the body upper and higher than the oil level of the oil reservoir in the operating state of the internal combustion engine mounted on a vehicle on a horizontal road surface The balancer body according to claim 1, further comprising a balancer oil discharge port formed at a position so as to allow the balancer chamber and the oil sump to communicate with each other. The internal combustion engine is an inline 4-cylinder, and each balancer shaft has a single balancer weight disposed between a pair of bearings constituted by the body upper and the body lower,
The body upper and the body lower support each balancer shaft in a state where the balancer weight is disposed at a position corresponding to a second throw as counted from a side opposite to the flywheel of the internal combustion engine in the crankshaft. The balancer body according to claim 1, wherein the balancer body is characterized.   The balancer body according to claim 2, wherein the balancer oil discharge port is disposed at a position corresponding to a suction port of an oil strainer provided in the oil reservoir in a crankshaft direction. When the internal combustion engine is mounted on the vehicle in a posture in which the crankshaft is horizontal and the cylinder axis is inclined, the pair of balancer shafts are arranged at different heights,
The balancer oil discharge port is formed in a pair corresponding to the pair of balancer shafts, and the balancer oil discharge port corresponding to the lower balancer shaft is disposed above the suction port of the oil strainer. The balancer body according to claim 4.

Images