JP6466817B2 - Balancer device for internal combustion engine - Google Patents

Description

  The present invention relates to a balancer device that cancels secondary vibrations of an internal combustion engine.

  In a reciprocating engine (hereinafter simply referred to as an engine) mounted on an automobile or the like, two balancer shafts each having an unbalanced weight (balancer weight) are gear-coupled to each other in order to cancel the secondary vibration generated by the piston. So that one drive balancer shaft is rotationally driven by a crankshaft via a power transmission mechanism, and the other driven balancer shaft is rotationally driven in the opposite direction at a constant speed by a drive shaft via a gear. The balancer device may be provided inside the oil pan.

  As such a balancer device, in order to reduce the agitation resistance of the oil by the balancer shaft, a plurality of oil discharge holes formed in the upper housing, the oil in the housing scraped up by rotation of the balancer shaft gear, balancer weight, etc. What is comprised so that it may discharge | emit to the exterior from is known (refer patent document 1). Since the balancer device of Patent Document 1 has an opening formed on the side surface of the housing, the oil stored in the oil pan always flows into the housing when provided so as to be immersed in the oil pan. obtain.

  On the other hand, an oil discharge passage formed in the upper part of the housing (gear cover member) is configured so that the oil stored in the oil pan does not flow in, and the oil accumulated in the housing after being used for lubrication of the balancer shaft Also known is a balancer device that discharges to the outside by rotation of the gear of the balancer shaft (see Patent Document 2). In the balancer device of Patent Document 2, the gear chamber and the weight chamber are partitioned by the bearing wall, and the oil supplied to the bearing portion is accumulated in the gear chamber and the weight chamber. Therefore, the bottom of the weight chamber and the gear chamber are stored in the bearing wall. A communication path that communicates with the bottom is formed.

JP 2003-262253 A JP 2000-104790 A

  However, in the balancer device of Patent Document 2, since the gear teeth of the pair of balancer shafts rotate so as to advance upward from each meshing portion, the oil accumulated in the housing cannot be efficiently discharged to the outside. . Therefore, the gear of the balancer shaft and the balancer weight are constantly stirring oil, and the oil stirring resistance is still large.

  In view of such a background, it is an object of the present invention to provide a balancer device for an internal combustion engine that can efficiently discharge the oil in the housing to the outside and has a small oil agitation resistance.

  In order to solve such a problem, the balancer device (10) of the internal combustion engine (1) according to the present invention is disposed horizontally in parallel with each other so as to have different axial heights, and gears (12Ld, 12Ud) and unbalanced weights (12Lc, 12Uc), and a lower balancer shaft (12L) and an upper balancer shaft (12U) that are driven to rotate in a direction in which the gear teeth advance downward from each meshing portion, A balancer housing (14) that defines at least a chamber (32, 33) for accommodating the gear and the unbalanced weight, and the balancer housing is formed so as to partition the chamber, and the lower balancer A shaft and a bearing wall (28) for supporting the upper balancer shaft, and the lower balancer shaft A communication path (35) formed along the axis of the lower balancer shaft so as to pass through at least the bearing wall (28) below and communicating the partitioned chamber, and an axial view of the lower balancer shaft In the chamber, the portion (32a) in which the communication passage is formed is formed in an arc shape along the outer peripheral surface of the gear toward the downstream side in the rotation direction of the gear (12Ld) of the lower balancer shaft, A drain passage circumferential bottom wall (48) that defines an oil drain passage (47) between the gear and an oil drain hole (49) formed in an upper portion of the drain passage circumferential bottom wall is provided. .

  According to this configuration, oil gathers below the gear of the lower balancer shaft through the communication path, and the collected oil is transported through the oil discharge passage where the teeth of the gear of the lower balancer shaft do not pass through the meshing portion. Therefore, the oil in the balancer housing can be efficiently discharged to the outside.

  In the above invention, the balancer housing collectively accommodates the gear and the unbalance weight, and at least the oil discharge passage (47) in the axial view of the lower balancer shaft. Is provided so as to sandwich at least the tooth tip portion of the gear from both sides in the thrust direction, and cooperates with the discharge passage peripheral bottom wall (48) to define the oil discharge passage into a groove cross-sectional shape. A pair of discharge passage side walls (54, 54), and at least one (right side) of the pair of discharge passage side walls is formed so as to protrude from an inner peripheral surface of the gear chamber, It is good to set it as the structure which has penetrated the said one of a pair of said discharge channel side walls.

  According to this configuration, even if the bearing wall is not provided between the gear and the unbalance weight and the gear chamber is configured to collectively accommodate the gear and the unbalance weight, the gear teeth This suppresses the oil conveyed through the oil discharge path from escaping from the gap. Thereby, oil can be efficiently discharged | emitted outside.

  In the above invention, the gap between the outer peripheral portion of the gear (12Ld) and the inner surface of the balancer housing when viewed from the axial direction of the lower balancer shaft is a portion corresponding to the oil discharge passage (47). It is good to set it as the structure set smaller than the circumference | surroundings of the said gear (12Ud) of a balancer shaft.

  According to this configuration, it is possible to suppress the oil scraped up from the oil discharge path by the gear teeth from the clearance between the outer peripheral portion of the gear and the bottom wall of the discharge path, and to efficiently discharge the oil to the outside. On the other hand, since the gap is large in other portions that do not correspond to the oil discharge path, the sliding resistance of the gear that does not contribute to oil discharge is reduced.

  In the above invention, the gap with the outer peripheral portion of the gear (12Ld) is made small at a position adjacent to the oil discharge hole (49) on the downstream side in the rotation direction of the gear (12Ld). The first rib (45) protruding from the inner surface of the balancer housing may be formed.

  According to this configuration, even if the oil conveyed through the oil discharge passage by the gear teeth passes through the oil discharge hole, the oil is blocked by the first rib, so that it is suppressed from returning to the upper balancer shaft side. . Thereby, the oil conveyed through the oil discharge passage by the gear teeth can be efficiently discharged to the outside.

  In the above invention, the outer peripheral portion of the gear (12Ld) is located at a position adjacent to the upstream side in the rotation direction of the gear (12Ld) with respect to the portion (32a) where the communication path (35) is formed. The second rib (46) protruding from the inner surface of the balancer housing may be formed so as to reduce the gap between the second balancer housing and the balancer housing.

  According to this configuration, the oil that has flowed below the gear of the lower balancer shaft through the communication path is prevented from flowing back to the upper balancer shaft side, which is opposite to the oil discharge path side, and oil agitation resistance can be reduced. . Moreover, it can suppress that the oil discharge efficiency falls by generation | occurrence | production of aeration.

  In the above invention, the balancer housing (14) is disposed inside the oil pan (6), and is positioned lower than the oil level (6o) of the oil pan when the engine is stopped in the balancer housing (14). It is preferable that a sub-oil discharge hole (44) for oil replacement having a smaller area than the oil discharge hole (49) is formed.

  According to this configuration, when the oil is changed, the oil in the balancer device is discharged from the sub oil discharge hole to the outside of the balancer device, so that the amount of oil that cannot be extracted from the balancer housing is reduced. During engine operation (during operation), the oil that receives centrifugal force due to the rotational movement of the gears exerts pressure on the bottom wall of the discharge path, so that the oil in the balancer housing outside the balancer device collected in the oil pan Intrusion into the is suppressed.

  Moreover, in said invention, it is good to set it as the structure where the height of a pair of said discharge channel side wall (54) is higher than the tooth height of the said gear (12Ld).

  According to this configuration, it is possible to suppress the oil conveyed through the oil discharge path by the gear teeth from escaping to the outside beyond the discharge path side wall. Thereby, the oil in the balancer housing is efficiently discharged to the outside.

  Further, in the above invention, the gear (12Ld) is a helical gear, and one side (right side) of the pair of the discharge path side walls (54) where the tooth groove of the gear is the rear side in the rotation direction of the gear. The gap between the discharge passage side wall (54) and the gear may be set smaller than the gap between the discharge passage side wall (54) on the other side (left side) and the gear.

  According to this configuration, the oil in the tooth groove that is pushed out to the side of the discharge passage side wall by the rotation of the gear is prevented from escaping to the outside through the gap between the gear and the discharge passage side wall. Can be efficiently discharged to the outside. Further, since the clearance between the other-side discharge path side wall and the gear, which has a small contribution to efficient oil discharge, is relatively large, the sliding resistance of the gear with respect to the other-side discharge path side wall is reduced.

  In the above invention, the balancer housing (14) further includes a peripheral wall (51) formed to protrude from the outer surface of the discharge passage peripheral bottom wall (48) so as to extend the oil discharge hole (49). And it is good to set it as the structure set so that the cross-sectional area of the said oil discharge hole may become large in the edge part by the side of the protrusion end of the said surrounding wall compared with the edge part by the side of the said oil discharge channel (47).

  According to this configuration, the peripheral wall can prevent oil flowing on the upper surface of the balancer housing from flowing into the balancer housing from the oil discharge hole. Further, the pressure loss of the oil discharged from the oil discharge hole can be reduced and the oil can be efficiently discharged to the outside.

  As described above, according to the present invention, it is possible to provide a balancer device for an internal combustion engine that can efficiently discharge the oil in the housing to the outside and has a small oil agitation resistance.

Sectional drawing which shows the engine lower part which concerns on embodiment along a lower balancer shaft Enlarged view of the balancer device shown in FIG. Sectional view along line III-III in FIG. The perspective view which looked at the balancer apparatus shown in FIG. 2 from upper direction Enlarged view of part V in FIG. VI-VI cross section in FIG. Explanatory drawing corresponding to FIG. 3 which shows the power transmission path | route of a balancer apparatus Sectional drawing which follows the VIII-VIII line in FIG. Sectional view along line IX-IX in FIG. Enlarged view of part X in FIG. (A) Cross section corresponding to FIG. 5 showing the oil level during engine operation, (B) during oil change

  Hereinafter, an embodiment in which a balancer device 10 according to the present invention is applied to an in-line four-cylinder automobile engine (hereinafter simply referred to as an engine 1) will be described in detail with reference to the drawings.

  As shown in FIG. 1, the engine 1 is an in-line four-cylinder engine in which a crankshaft 2 extends horizontally in the horizontal direction, and the vehicle has an attitude in which a cylinder axis X (see FIGS. 8 and 9) is inclined backward. Mounted on. The vertical direction is determined when the engine 1 is mounted on the automobile, but the inclination angle of the cylinder axis X is set to 45 degrees or less, and the cylinder axis X is closer to the vertical direction than the horizontal direction. For convenience, the cylinder axis X direction may be described as being up and down. In FIG. 1, the cylinder axis X direction is indicated as “upper and lower”. The crank axis extends horizontally in a direction perpendicular to the cylinder axis X, and this direction is the left and right. It should be noted that the left and right directions are based on the paper surface of FIG.

  The engine 1 forms a cylinder and has an upper block 3 having a skirt portion at the lower portion, and a lower block 5 coupled to the lower portion of the upper block 3 and defining a crank chamber 4 in cooperation with the skirt portion of the upper block 3. An oil pan 6 that is coupled to the lower part of the lower block 5 and defines an oil reservoir below the crank chamber 4; a balancer device 10 that is coupled to the lower part of the lower block 5 and disposed inside the oil pan 6; ing. Hereinafter, the upper block 3 and the lower block 5 are collectively referred to as a cylinder block 7.

  The crankshaft 2 has four crankpins 2a (hereinafter referred to as first to fourth crankpins 2a in order from the left side) that are connected via a connecting rod 8 and a piston pin of a piston (not shown) that is slidably provided in the cylinder. ), Five journals 2b (hereinafter referred to as the first to fifth journals 2b in order from the left side) provided at positions sandwiching the crankpin 2a, a crank arm 2c for connecting the journal 2b and the crankpin 2a, and a crank arm 2c is provided with a counterweight 2d integrally formed on the side opposite to the crankpin 2a. The first and fourth crankpins 2a are disposed at the same phase position, and the second and third crankpins 2a are disposed at the same phase position that is 180 degrees out of phase with the first and fourth crankpins 2a. .

  The support wall for supporting the first and fifth journals 2b of the crankshaft 2 is constituted by the left wall and the right wall of the cylinder block 7, and the support wall for supporting the second to fourth journals 2b is provided in the crank chamber 4. It is comprised by the provided partition.

  The left end of the crankshaft 2 extends further leftward from the first journal 2 b and protrudes from the left wall of the cylinder block 7. The protruding portion includes a relatively small-diameter small sprocket 2e for driving a camshaft (not shown) and a relatively large-diameter large sprocket 2f (drive sprocket) for driving the balancer device 10 on the first journal 2b side. It is fixed in this order. A chain case 9 is provided outside the large sprocket 2f so as to penetrate the crankshaft 2. A crank pulley 2g for driving an auxiliary machine of the engine 1 is fixed to the left end of the crankshaft 2 located outside the chain case 9.

  The balancer device 10 is fixed to the cylinder block 7 so as to be centered on a plane passing through the four cylinder axes X in order to reduce the secondary vibration of the engine 1 caused by the reciprocating motion of the piston. 6 is immersed in oil.

  As shown in FIGS. 2 and 3, the balancer device 10 includes a pair of front and rear balancer shafts 12 (12 </ b> L and 12 </ b> U) disposed in parallel with the crankshaft 2 at positions lower than the crankshaft 2. The pair of balancer shafts 12 are disposed at the same height with respect to the cylinder axis X direction. Since the cylinder axis X is inclined rearward, the rear balancer shaft 12 is disposed at a position lower than the front balancer shaft 12 (see FIG. 9). Hereinafter, the rear balancer shaft 12 arranged at a low position is referred to as a lower balancer shaft 12L, and the front balancer shaft 12 arranged at a high position is referred to as an upper balancer shaft 12U.

  On the left side of the lower balancer shaft 12L, there is disposed an input shaft 13 having one end to which a driven sprocket 13a, which will be described later, is fixed, and to which the driving force of the crankshaft 2 is input. The input shaft 13 and the lower balancer shaft 12L are coaxially disposed so as to be relatively rotatable with each other. The two balancer shafts 12L and 12U and the input shaft 13 are supported by the balancer housing 14 and are housed in the balancer housing 14 in a manner in which the driven sprocket 13a is disposed outside.

  The balancer housing 14 includes a generally box-shaped upper housing 14U and a lower housing 14L which are divided into two vertically along a plane passing through the axis (rotation center) of the balancer shafts 12L and 12U. The upper housing 14U and the lower housing 14L are shaped to form an opening in the right side wall when assembled together. This opening is necessary when processing journal bearings 21 to 25, which will be described later, and is closed by a housing plate 14P provided with a seal member at the periphery when assembled.

  As shown in FIGS. 3 and 4, the balancer housing 14 is lower by through bolts B1 inserted from below into bolt insertion holes 14a (six positions shown in FIG. 3 in this embodiment) provided at appropriate positions. Fastened to the lower surface of the block 5.

  Returning to FIGS. 2 and 3, the balancer housing 14 is formed with five journal bearings 21 to 25 constituted by half bearings formed in the upper housing 14U and the lower housing 14L, respectively. The first to third journal bearings 21 to 23 are arranged in order from the left on the axis (axis and extension thereof) of the lower balancer shaft 12L, and the fourth and fifth journal bearings 24 and 25 are arranged on the upper balancer shaft 12U. Arranged in order from the left on the axis. In the present specification, the phrase “arranged on the axis (or axis)” for the bearing means that the bearing is arranged around the axis (or axis) coaxially with the axis (or axis). is there.

  The first journal bearing 21 is formed at the left end of the balancer housing 14. The first journal bearing 21 is formed like a continuous bearing in the upper housing 14U, while the lower housing 14L is divided into left and right by a bearing circumferential groove 21a provided at an intermediate portion in the axial direction. . Hereinafter, the left portion of the first journal bearing 21 in the lower housing 14L is referred to as a left half first journal bearing 21L, and the right portion is referred to as a right half first journal bearing 21R. The first journal bearing 21 is configured as a cylindrical first bearing wall 26 (see FIG. 4) surrounding the input shaft 13.

  The 4th journal bearing 24 and the 5th journal bearing 25 are arrange | positioned ahead of these in the same position about the left-right direction with the 2nd journal bearing 22 and the 3rd journal bearing 23, respectively. The second journal bearing 22 and the fourth journal bearing 24 are configured as an integrated second bearing wall 27 continuous in the front-rear direction, and the third journal bearing 23 and the fifth journal bearing 25 are integrated in the front-rear direction. The third bearing wall 28 is configured. The width of the first bearing wall 26 (axial dimension; the same applies hereinafter) is larger than the width of the second bearing wall 27 and the third bearing wall 28, and the width of the third bearing wall 28 is the same as that of the second bearing wall 27. It is larger than the width.

  As shown in FIGS. 3 and 4, the upper housing 14U and the lower housing 14L are fastened to each other by a plurality of bolts B2 inserted into a plurality of bolt holes 14b arranged at appropriate positions. The bolt hole 14b is configured as an insertion hole penetrating the upper housing 14U in the upper housing 14U, and is configured as a female screw hole in which the bolt B2 is screwed in the lower housing 14L. The bolt B2 is inserted into the bolt hole 14b from above. Inserted. A female screw hole to which an oil passage described later is connected has a bottom.

  As shown in FIGS. 2 and 3, the input shaft 13 is provided so as to protrude leftward from the balancer housing 14, and the above described projecting end is disposed at a position corresponding to the large sprocket 2f in the crank axis direction. The driven sprocket 13a is fixed. The input shaft 13 has a first journal 13b (13bL, 13bR) formed near the right side of the driven sprocket 13a, and a second journal 13c formed at the right end. The first journal 13 b of the input shaft 13 is pivotally supported by the first journal bearing 21, and the second journal 13 c is pivotally supported by the second journal bearing 22.

  The first journal 13b is divided into left and right by a journal circumferential groove 13f formed at the center in the axial direction. The journal circumferential groove 13f is formed at a position corresponding to the axial direction of the bearing circumferential groove 21a formed in the lower half (lower housing 14L) of the first journal bearing 21 with the same width as the bearing circumferential groove 21a. ing. Hereinafter, the left portion of the journal circumferential groove 13f in the first journal 13b is referred to as a left half first journal 13bL, and the right portion is referred to as a right half first journal 13bR. In the lower housing 14L, the left half first journal 13bL of the input shaft 13 is pivotally supported by the left half first journal bearing 21L, and the right half first journal 13bR is pivotally supported by the right half first journal bearing 21R.

  A roller chain 15 is wound around the large sprocket 2 f of the crankshaft 2 and the driven sprocket 13 a of the input shaft 13. That is, the large sprocket 2f, the roller chain 15, and the driven sprocket 13a constitute a winding-type first transmission mechanism 16 that transmits the rotational force of the crankshaft 2 to the input shaft 13. The driven sprocket 13a has a smaller diameter than the large sprocket 2f. The input shaft 13 rotates in the same direction as the crankshaft 2 at a higher speed than the crankshaft 2 by the first transmission mechanism 16.

  On the right side of the first journal 13b of the input shaft 13, a bowl-shaped thrust plate 13d (collar) having an enlarged diameter is integrally formed, and on the right side of the thrust plate 13d (between the thrust plate 13d and the second journal 13c). The first helical gear 13e having a relatively large diameter is fixed. Both surfaces of the thrust plate 13d (both end surfaces in the axial direction of the input shaft 13) serve as thrust surfaces that transmit the thrust load of the input shaft 13 to the balancer housing 14, as will be described later.

  In order to form a thrust bearing at a position corresponding to the thrust plate 13d of the balancer housing 14 to receive at least a peripheral edge portion of the thrust plate 13d and to support a thrust load transmitted from both surfaces of the thrust plate 13d at least partially. The groove 14c (14Uc, 14Lc) is formed in an annular shape.

  As shown in FIG. 5 which is an enlarged view of a V portion in FIG. 1, the groove 14c has a width wider than the thrust plate 13d in the upper housing 14U, and receives the thrust plate 13d in a non-contact state. The groove 14Uc is formed in a semicircular arc shape. On the other hand, in the lower housing 14L, the groove 14c has substantially the same width as the thrust plate 13d, and supports a thrust load of the input shaft 13 via a thin fluid film in surface contact with both surfaces of the thrust plate 13d. The thrust bearing grooves 14Lc forming the thrust bearing surfaces 14d and 14d are formed in a semicircular arc shape. That is, the wall portion in which the thrust bearing groove 14 </ b> Lc of the lower housing 14 </ b> L is formed constitutes the thrust bearing of the input shaft 13.

  As described above, the input shaft 13 that is rotationally driven by the roller chain 15 is subjected to an upward force F on the driven sprocket 13a that is the driven portion. Therefore, the width (a + b) of the portion where the first journal 13b (13bL, 13bR) of the input shaft 13 overlaps the first journal bearing 21 of the upper housing 14U in the axial direction is the first journal of the lower housing 14L. It is larger than the width (c + d) of the portion overlapping the bearing 21 in the axial direction. That is, the lower portion of the first journal bearing 21 is divided into two in the axial direction by the bearing circumferential groove 21a formed on the bearing surface, so that the first journal bearing 21 does not receive the force F. The sliding resistance with respect to the first journal bearing 21 of 13b is reduced.

  In addition, a semicircular oil supply groove 21b is formed in the axial intermediate portion of each of the left half first journal bearing 21L and the right half first journal bearing 21R of the lower housing 14L. Therefore, the width of the portion where the first journal 13b is in sliding contact with the lower housing 14L is smaller than the width (c + d) of the overlapping portion. As a result, the sliding resistance of the first journal 13b with respect to the first journal bearing 21 is further reduced below the first journal bearing 21 where the force F is not applied. Further, in the upper part of the first journal bearing 21 to which the force F is applied, a large bearing area is secured while the axial dimension is kept small. As a result, the first journal bearing 21 is downsized in the axial direction while ensuring a necessary bearing width corresponding to the force F at the top.

  As shown in FIGS. 5 and 6, the shafts 12, 13 do not rotate between the left half first journal bearing 21 </ b> L and the right half first journal bearing 21 </ b> R in the lower housing 14 </ b> L when the balancer device 10 is assembled. Thus, a pin insertion hole 14e for inserting a pin (not shown) and fixing the input shaft 13 is formed. The pin insertion hole 14e penetrates the first journal bearing 21 in the radial direction and opens into the bearing hole of the first journal bearing 21 at the bottom of the bearing circumferential groove 21a. On the lower surface of the first journal bearing 21, an annular projecting portion 14f projecting downward is formed so as to surround the opening of the pin insertion hole 14e, and the pin insertion hole 14e extends downward.

  A pin insertion hole 13g extending in the radial direction is formed at a position corresponding to the pin insertion hole 14e in the input shaft 13 in the axial direction. The pin insertion hole 13g is formed in the first journal 13b so as to open at the bottom of the journal circumferential groove 13f, and is a bottomed hole in this embodiment. In another embodiment, the pin insertion hole 13g may penetrate the first journal 13b in the radial direction.

  When the pin insertion hole 13g is processed, burrs may be generated around the pin insertion hole 13g. When the burr generated around the pin insertion hole 13g comes into contact with the first journal bearing 21, the sliding friction of the first journal 13b portion of the input shaft 13 increases, but the pin insertion hole 13g is formed in the journal circumferential groove 13f. Since the opening is at the bottom, the burr does not contact the first journal bearing 21. Thereby, increase of the sliding friction of the input shaft 13 is suppressed.

  When the balancer device 10 is assembled, rotation of the shafts 12 and 13 is restricted by inserting pins (not shown) from below with the pin insertion holes 13g aligned with the pin insertion holes 14e. That is, the pin insertion hole 14 e is a hole for positioning and fixing the shafts 12 and 13 with respect to the balancer housing 14. With the pin inserted into the pin insertion hole 14e, the roller chain 15 is wound around the large sprocket 2f of the crankshaft 2 and the driven sprocket 13a of the balancer device 10 adjusted to the rotation angle shown in FIG. As a result, the balancer device 10 generates an inertial force at the timing when the secondary vibration of the engine 1 is canceled.

  In this manner, the pin insertion hole 13g is formed in the first journal 13b of the input shaft 13, and the pin insertion hole 14e is formed at a position corresponding to the pin insertion hole 13g of the first journal bearing 21 of the balancer housing 14 in the axial direction. As a result of the formation, oil entering the inside through the pin insertion hole 14e is blocked by the left half first journal 13bL and the right half first journal 13bR. This prevents oil from entering the portion of the balancer housing 14 containing the helical gears 12Ld, 12Ud, 12Ue, and 13e (FIG. 3) through the pin insertion hole 14e, thereby suppressing an increase in oil stirring resistance. The

  Further, in the lower part of the first journal bearing 21, a pin insertion hole 14e is formed so as to open at the bottom of the bearing circumferential groove 21a, so that the first journal 13b is formed with respect to the first journal bearing 21 as described above. Not only the sliding resistance is reduced, but also the oil flowing out from the bearing gap of the first journal 13b is expelled from the pin insertion hole 14e, and the sliding resistance of the first journal 13b to the oil is also reduced. That is, since the pin insertion hole 14e opens downward, the air in the bearing circumferential groove 21a cannot escape even after the oil is filled in the oil pan 6, and remains in the bearing circumferential groove 21a. Create an air pocket. As a result, the oil flowing out from the bearing gap of the first journal 13b flows down in the air due to gravity and is discharged from the pin insertion hole 14e. Therefore, the first journal 13b is rotated in the air in the bearing circumferential groove 21a, and the sliding resistance is smaller than that in the case of rotating in oil.

  And since the annular protrusion 14f which extends the pin insertion hole 14e is formed and the layer of the air pool becomes thick, the outflow of air, that is, the infiltration of oil is suppressed even when the oil level changes during turning of the vehicle. The annular protrusion 14f also functions as a reinforcing rib around the pin insertion hole 14e whose rigidity has been reduced by the formation of the pin insertion hole 14e.

  Returning to FIG. 2 and FIG. 3, the description will be continued. Both balancer shafts 12L and 12U are respectively positioned at positions corresponding to the first journals 12La and 12Ua formed at positions corresponding to the second and fourth journal bearings 22 and 24, and the third and fifth journal bearings 23 and 25, respectively. The formed second journals 12Lb and 12Ub are provided. The balancer shafts 12L and 12U are provided on the left and right sides of the second journals 12Lb and 12Ub, respectively, and a pair of left and right balancer weights 12Lc of substantially the same shape with the center of gravity displaced radially outward from the rotation center. 12Lc, 12Uc · 12Uc, and first helical gears 12Ld, 12Ud fixed between the left balancer weights 12Lc, 12Uc and the first journals 12La, 12Ua.

  The second journal bearing 22 pivotally supports both the second journal 13c of the input shaft 13 and the first journal 12La of the lower balancer shaft 12L. The second journal 13c of the input shaft 13 and the first journal 12La of the lower balancer shaft 12L have the same length, and face each other with a slight gap at the intermediate position in the length direction of the second journal bearing 22. Has been placed. Accordingly, the first journal 12La of the lower balancer shaft 12L is about half the length of the first journal 12Ua of the upper balancer shaft 12U.

  A bearing metal 29 is disposed on the third journal bearing 23 and the fifth journal bearing 25 that pivotally support the second journals 12Lb and 12Ub between the left and right balancer weights 12Lc and 12Uc.

  In the balancer shafts 12L and 12U, the portions of the pair of left and right balancer weights 12Lc and 12Uc that are opposed to each other are formed in a bowl shape whose diameter is larger than that of the second journals 12Lb and 12Ub. The inner surface is a thrust surface that transmits a thrust force to the third bearing wall 28. That is, the third bearing wall 28 that forms the third and fifth journal bearings 23 and 25 also serves as a thrust bearing that supports the axial loads of the balancer shafts 12L and 12U.

  In the lower balancer shaft 12L, the first journal 12La forms the left end as described above. On the other hand, the upper balancer shaft 12U extends further leftward from the first journal 12Ua, and a second helical gear 12Ue that meshes with the first helical gear 13e of the input shaft 13 is fixed to the extended portion. That is, the first transmission gear 17 that transmits the rotational force of the input shaft 13 to the upper balancer shaft 12U is configured by the first helical gear 13e and the second helical gear 12Ue. As a result, the upper balancer shaft 12U rotates in the direction opposite to the input shaft 13. Note that the directions of twisting of the second helical gear 12Ue and the first helical gear 12Ud of the upper balancer shaft 12U are the same, thereby reducing the axial load of the upper balancer shaft 12U.

  The first helical gear 12Ud of the upper balancer shaft 12U and the first helical gear 12Ld of the lower balancer shaft 12L are engaged with each other, and the rotational force of the upper balancer shaft 12U is applied to the lower balancer shaft 12L by the first helical gears 12Ud and 12Ld. A third transmission mechanism 18 for transmission is configured. The first helical gears 12Ud and 12Ld constituting the third transmission mechanism 18 have the same diameter and the same number of teeth (speed-up gear ratio = 1), and both balancer shafts 12L and 12U are the same in opposite directions. Rotates at a rotational speed (angular speed).

  As described above, the balancer housing 14 is configured to suppress at least the helical gears 12Ld, 12Ud of the shafts 12L, 12R, 13 except for the end of the input shaft 13 where the driven sprocket 13a is provided in order to suppress an increase in friction due to oil agitation. , 12Ue, 13e and balancer weights 12Lc, 12Uc are accommodated so that the shafts 12L, 12R, 13 are accommodated, and a liquid-tight structure in which oil cannot enter from other than the pin insertion hole 14e and oil discharge holes 43, 49 described later It has become.

  The speed increasing ratio of the first transmission mechanism 16 and the second transmission mechanism 17 is set so that both the balancer shafts 12L and 12U have a rotational speed twice that of the crankshaft 2. Specifically, in the present embodiment, the chain transmission speed ratio of the first transmission mechanism 16 is set to 4/3, the speed increase gear ratio of the second transmission mechanism 17 is set to 3/2, and the first transmission mechanism The speed increasing ratio of the mechanism that combines 16 and the second transmission mechanism 17 is 2.

  Accordingly, when the rotational speed of the crankshaft 2 is 1, the rotational speed of the input shaft 13 is 4/3 (the same direction as the crankshaft 2), and the rotational speed of the lower balancer shaft 12L is 2 (the same direction as the crankshaft 2). Thus, the relative rotational speed of the lower balancer shaft 12L with respect to the input shaft 13 (that is, the rotational speed of the first journal 12La of the lower balancer shaft 12L with respect to the second journal 13c of the input shaft 13 which is a bearing) is 2/3 (= 2−2). 4/3). The rotation speed ratio is 3/2 (= 2 / (4/3).

  Further, when the diameter and the number of teeth (the number of teeth) of the driven sprocket 13a are 3/4 times the diameter and the number of the large sprocket 2f (FIG. 1), the rotational speed of the input shaft 13 is twice that of the crankshaft 2. It becomes larger than ratio (1/2 times). Thereby, the noise in the 1st transmission mechanism 16 becomes small.

  On the other hand, the diameter and the number of teeth of the first helical gear 13e of the input shaft 13 are 3/2 times the diameter and the number of teeth of the second helical gear 12Ue of the upper balancer shaft 12U, and the rotational speed of the input shaft 13 is 2 times that of the crankshaft 2. It becomes larger than the ratio (1 time) when doubling. As a result, the diameter of the first helical gear 13e of the input shaft 13 is increased, and the oil is efficiently scraped as will be described later.

  In the balancer device 10 configured as described above, power is transmitted as indicated by a black arrow in FIG. That is, the rotational force of the crankshaft 2 is transmitted to the input shaft 13 via the large sprocket 2f (FIG. 1), the roller chain 15 (FIG. 1) and the driven sprocket 13a of the first transmission mechanism 16, and is indicated by a white arrow. Thus, the input shaft 13 is driven to rotate in the same rotational direction as the crankshaft 2.

  The rotational force of the input shaft 13 is transmitted to the upper balancer shaft 12U via the first helical gear 13e and the second helical gear 12Ue constituting the second transmission mechanism 17, and is in the reverse direction to the input shaft 13 as indicated by the white arrow. The upper balancer shaft 12U is driven to rotate. As described above, the upper balancer shaft 12U rotates in the opposite direction to the crankshaft 2 at a rotational speed twice that of the crankshaft 2.

  The rotational force of the upper balancer shaft 12U is transmitted to the lower balancer shaft 12L via the two first helical gears 12Ud and 12Ld constituting the third transmission mechanism 18, and is opposite to the upper balancer shaft 12U as indicated by the white arrow. The lower balancer shaft 12L is rotationally driven in the direction at the same rotational speed as the upper balancer shaft 12U. Accordingly, the pair of front and rear balancer shafts 12L and 12U generate an inertial force in the cylinder axis X direction that cancels the secondary vibration of the engine 1.

  In the present embodiment, the lower balancer shaft 12L and the input shaft 13 are separated from each other in order to increase the rotation of the crankshaft 2 stepwise and transmit it to the balancer shaft 12, but the shafts 12L, 13 are Both are arranged coaxially and are driven to rotate by the crankshaft 2 in order to generate an inertial force that reduces the secondary vibration of the engine 1. Therefore, the input shaft 13 can be regarded as a divided part of the balancer shaft 12L.

  Engine oil that is sucked from an inlet of an oil strainer in the oil pan 6 by an oil pump (not shown) and pumped toward each part of the engine 1 is supplied to each sliding portion of the balancer device 10 through an oil passage. Used as a lubricating oil. Specifically, in the balancer device 10, engine oil is supplied to the first to fifth journal bearings 21 to 25.

  Hereinafter, the configuration of the oil passage in the balancer device 10 will be described. As shown in FIG. 1, an in-block oil passage 7 a that supplies oil from the main gallery to the balancer device 10 is provided on the support wall that supports the first journal 2 b of the crankshaft 2. As shown in FIG. 4, the oil supplied from the block internal oil passage 7a is introduced into the balancer device 10 from the upper surface of the upper housing 14U and passes through an oil passage (not shown) extending vertically to the lower housing 14L. Supplied to the joint surface.

  As shown in FIG. 3, oil passage grooves 30 (30A, 30B, 30C) are formed on the upper surface of the lower housing 14L. Although detailed illustration is omitted, an oil passage groove 30 is similarly formed on the lower surface of the upper housing 14U. In the oil passage groove 30, the left end portion of the rear end of the lower housing 14L serves as an oil inlet 30a. The oil passage groove 30 branches into a first branch groove 30A extending forward from the oil inlet 30a and a second branch groove 30B extending rightward.

  The first branch groove 30A is curved before extending forward from the oil inlet 30a, extends to the left and branches at the first bearing wall 26, and as shown in FIG. Oil is supplied to a bearing gap between the first journal bearing 21 and the first journal 13b of the input shaft 13 from an oil supply groove 21g formed in an arc shape in the lower half of the bearing surface of the bearing 21L and the right half first journal bearing 21R. Supply. The first branch groove 30A is formed in an annular shape along the periphery of the bolt hole 14b (around the bolt B2).

  The second branch groove 30B extends rightward from the oil inlet 30a, curves and extends forward at the rear end portion of the second bearing wall 27, and extends along the periphery of the bolt hole 14b. It reaches the rear end. The second branch groove 30B is formed in an annular shape along the bearing surface of the second journal bearing 22, and the second journal 13c of the input shaft 13 and the first journal 12La of the lower balancer shaft 12L and the second journal bearing 22 are formed. Oil is supplied to the bearing gap between. The second branch groove 30 </ b> B extends forward again from the front end of the second journal bearing 22, extends along the periphery of the bolt hole 14 b, and then reaches the rear end of the fourth journal bearing 24. Also in the fourth journal bearing 24, the second branch groove 30B is formed in an annular shape along the bearing surface at the center in the width direction of the fourth journal bearing 24, and the fourth journal bearing 24 and the upper balancer shaft 12U. Oil is supplied to the bearing gap between one journal 12Ua.

  Further, a third branch groove 30C branched from the second branch groove 30B is formed on the upper surface of the rear wall of the lower housing 14L. The third branch groove 30C extends rightward from the second branch groove 30B, curves and extends forward at the rear end portion of the third bearing wall 28, and extends along the periphery of the bolt hole 14b. 23 reaches the rear end. The third branch groove 30 </ b> C is formed in an annular shape along the outer peripheral surface of the bearing metal 29 in the third journal bearing 23, and the third journal bearing 23 and the lower balancer pass through a through hole formed in the bearing metal 29. Oil is supplied to the bearing gap between the shaft 12L and the second journal 12Lb. The second branch groove 30 </ b> B extends forward again from the front end of the third journal bearing 23, extends along the periphery of the bolt hole 14 b, and then reaches the rear end of the fifth journal bearing 25. Also in the fifth journal bearing 25, the second branch groove 30 </ b> B is formed in an annular shape along the outer peripheral surface of the bearing metal 29, and passes through the through hole formed in the bearing metal 29 and the fifth journal bearing 25. Oil is supplied to the bearing gap between the balancer shaft 12U and the second journal 12Ub.

  The above is the configuration of the oil supply path for the journal bearings 21 to 25. In this way, oil is supplied to the balancer device 10 when the engine 1 is operating (during operation), and the journal bearings 21 to 25 are lubricated by the oil. Since the oil used for lubrication flows out from the bearing gap, it accumulates in the balancer housing 14. Further, when the engine 1 is stopped, the oil pumping by the oil pump is stopped, but the oil in the main gallery formed in the cylinder block 7 leaks from the bearing gaps of the journal bearings 21 to 25 due to gravity. Again, the oil accumulates in the balancer housing 14. As described above, the balancer housing 14 has a liquid-tight structure. Therefore, the balancer device 10 has a mechanism that can discharge the oil in the balancer housing 14 to the outside. Hereinafter, the oil discharge mechanism will be described.

  2 and 3, the balancer housing 14 includes a plurality of chambers (first chamber 31 to third chamber 33 in order from the left) partitioned by the first bearing wall 26 to the third bearing wall 28. .) Is defined inside. The first chamber 31 is defined between the first bearing wall 26 and the second bearing wall 27, and accommodates the thrust plate 13d and the first helical gear 13e of the input shaft 13, and the second helical gear 12Ue of the upper balancer shaft 12U. doing. The second chamber 32 is defined between the second bearing wall 27 and the third bearing wall 28 and accommodates the first helical gears 12Ld and 12Ud of the balancer shafts 12L and 12U and the balancer weights 12Lc and 12Uc on the left side. Yes. The third chamber 33 is defined between the third bearing wall 28 and the housing plate 14P and accommodates the right balancer weights 12Lc and 12Uc.

  Part of the oil supplied to the first journal bearing 21 and part of the oil supplied to the second and fourth journal bearings 22 and 24 flow into the first chamber 31. Part of the oil supplied to the second and fourth journal bearings 22 and 24 and part of the oil supplied to the third and fifth journal bearings 23 and 25 flow into the second chamber 32. Part of the oil supplied to the third and fifth journal bearings 23 and 25 flows into the third chamber 33.

  The oil that has flowed into the first chamber 31 to the third chamber 33 is scraped up by the first helical gear 13e of the input shaft 13 and the first helical gear 12Ld of the lower balancer shaft 12L, and is discharged to the outside of the balancer housing 14. Hereinafter, the oil discharge structure of the first chamber 31 to the third chamber 33 will be described.

  As shown in FIGS. 2, 8, and 9, the lower housing 14 </ b> L is positioned below the input shaft 13 and the lower balancer shaft 12 </ b> L so as to extend in the left-right direction in parallel with the shafts 13, 12 </ b> L. A communication passage 35 is formed through the bearing wall 27 to communicate the first chamber 31 and the second chamber 32, and to communicate the second chamber 32 and the third chamber 33 through the third bearing wall 28. ing. The communication passage 35 has a spherical shape in which a straight hole that penetrates the right wall from the right side of the lower housing 14L to the first chamber 31 using a drill and is press-fitted into the right wall of the lower housing 14L. It is formed by closing with a plug 36.

  The communication path 35 is formed below the first helical gear 13 e of the input shaft 13. The lower housing 14L is formed with a rib-like portion 37 protruding from the lower surface so as to form the communication passage 35. The first chamber 31 to the third chamber 33 extend downward from the lowest position to form a rib shape. It has the extension parts 31a, 32a, and 33a extended so that the part 37 might be reached. Accordingly, the lowest extending portions 31 a, 32 a, 33 a of the first chamber 31 to the third chamber 33 communicate with each other through the communication path 35. Further, the communication path 35 is provided at a position lower than the oil surface 6 o of the oil pan 6. That is, the balancer housing 14 is disposed at a position where the lower portion of the first chamber 31 to the third chamber 33 is lower than the oil level 6 o of the oil pan 6. The oil level 6o of the oil pan 6 means that when the engine 1 is operating (during operation) unless otherwise specified.

  When the shafts 12L, 12U, and 13 are rotationally driven in the direction described with reference to FIG. 7, the first helical gear 13e of the input shaft 13 and the second helical gear 12Ue of the upper balancer shaft 12U shown in FIG. The teeth formed in the part rotate in the direction of proceeding downward from the meshing part of each other. Further, the first helical gear 12Ld of the lower balancer shaft 12L and the first helical gear 12Ud of the upper balancer shaft 12U shown in FIG. 9 also rotate in the direction in which the teeth formed on the outer peripheral portion proceed downward from the meshing portions.

  As shown in FIG. 8, the oil in the first chamber 31 is scraped up by the first helical gear 13 e of the input shaft 13 and discharged to the outside. That is, when viewed from the axial direction of the lower balancer shaft 12L, it is formed in an arc shape along the outer peripheral surface of the first helical gear 13e from the extending portion 31a of the first chamber 31 toward the downstream side in the rotational direction of the first helical gear 13e. Further, the arc-shaped portion of the balancer housing 14 forms a first discharge path peripheral bottom wall 42 that defines a first oil discharge path 41 between the balancer housing 14 and the first helical gear 13e. The clearance between the outer peripheral portion of the first helical gear 13e and the inner surface of the balancer housing 14 is greater than the periphery of the second helical gear 12Ue of the upper balancer shaft 12U in the first discharge passage peripheral bottom wall 42 corresponding to the first oil discharge passage 41. It is getting smaller.

  In the rear part of the first chamber 31, a first oil discharge hole 43 extending upward along the cylinder axis X direction is provided in the upper part of the first discharge path circumferential bottom wall 42. The first oil discharge hole 43 opens on the upper surface of the upper housing 14U at a position higher than the oil surface 6o of the oil pan 6. Further, at an intermediate portion in the height direction of the first discharge path circumferential bottom wall 42 and lower than the oil surface 6o of the oil pan 6 when the engine 1 is stopped, an area smaller than the first oil discharge hole 43 is provided. A sub-oil discharge hole 44 for changing oil is formed.

  At the position adjacent to the first oil discharge hole 43 in the upper housing 14U on the downstream side in the rotational direction of the first helical gear 13e, the inner surface of the upper housing 14U is made small so as to reduce the gap with the outer peripheral portion of the first helical gear 13e. The 1st rib 45 which protrudes from is formed. Further, at the position adjacent to the upstream side in the rotation direction of the first helical gear 13e with respect to the extending portion 31a of the first chamber 31 in the lower housing 14L, the gap with the outer peripheral portion of the first helical gear 13e is made small. A second rib 46 protruding from the inner surface of the lower housing 14L is formed. The first rib 45 and the second rib 46 are a part of the first discharge path peripheral bottom wall 42 that extends the first oil discharge path 41 beyond the first oil discharge hole 43 and the extending portion 31 a of the first chamber 31. It can also be said.

  As shown in FIG. 9, the oil in the second chamber 32 is scraped up by the first helical gear 12Ld of the lower balancer shaft 12L and discharged to the outside. That is, in the axial view of the lower balancer shaft 12L, it is formed in an arc shape along the outer peripheral surface of the first helical gear 12Ld from the extending portion 32a of the second chamber 32 toward the downstream side in the rotational direction of the first helical gear 12Ld. Further, the arc-shaped portion of the balancer housing 14 forms a second discharge path peripheral bottom wall 48 that defines a second oil discharge path 47 between the balancer housing 14 and the first helical gear 12Ld. The clearance between the outer peripheral portion of the first helical gear 12Ld and the inner surface of the balancer housing 14 is smaller than the periphery of the first helical gear 12Ud of the upper balancer shaft 12U in the second discharge passage peripheral bottom wall 48 corresponding to the second oil discharge passage 47. It has become.

  In the rear part of the second chamber 32, a second oil discharge hole 49 extending upward along the cylinder axis X direction is provided in the upper part of the second discharge path circumferential bottom wall 48. The second oil discharge hole 49 opens on the upper surface of the upper housing 14U at a position higher than the oil surface 6o in the oil pan 6.

  Further, the upper housing 14U is also arranged at a position adjacent to the downstream side in the rotational direction of the first helical gear 12Ld with respect to the second oil discharge hole 49 in the upper housing 14U so as to reduce the gap with the outer peripheral portion of the first helical gear 12Ld. The 1st rib 45 which protrudes from the inner surface of is formed. Further, the clearance from the outer peripheral portion of the first helical gear 12Ld is also reduced at a position adjacent to the extending portion 32a of the second chamber 32 in the lower housing 14L on the upstream side in the rotational direction of the first helical gear 12Ld. A second rib 46 protruding from the inner surface of the lower housing 14L is formed. The first rib 45 and the second rib 46 are a part of the second discharge path peripheral bottom wall 48 that extends the second oil discharge path 47 beyond the second oil discharge hole 49 and the extending portion 32 a of the second chamber 32. It can also be said.

  As shown in FIGS. 4, 8 and 9, the first and second oil discharge holes 43 and 49 are extended on the upper surface of the rear portion of the upper housing 14U, that is, on the lower side of the inclined upper surface. And the 1st surrounding wall 50 and the 2nd surrounding wall 51 which protrude from the outer surface of the 2nd discharge path surrounding bottom walls 42 and 48 are formed. The first and second oil discharge holes 43 and 49 have a larger cross-sectional area at the upper ends on the projecting end sides of the corresponding first and second peripheral walls 50 and 51 than the lower ends on the corresponding oil discharge passages 41 and 47 side. It is a stepped hole and extends in the tangential direction of the corresponding first helical gears 13e, 12Ld.

  A ventilation passage 52 that penetrates through the second bearing wall 27 and the third bearing wall 28 is formed in the vicinity of the upper ends of the first chamber 31 to the third chamber 33. The ventilation passage 52 is formed linearly along a protrusion 14g formed so as to protrude from the upper surface of the upper housing 14U above the upper balancer shaft 12U. The ventilation passage 52 passes through the left side wall facing the second bearing wall 27 across the first chamber 31 and opens to the left outer side surface 14h (FIG. 4), thereby communicating between the inside and the outside of the balancer housing 14. I am letting. The ventilation passage 52 has a smaller diameter than the communication passage 35, and is formed by drilling a hole from the left side of the upper housing 14U through the left wall to the third chamber 33 using a drill. As a result, the pressure inside the balancer housing 14 does not become lower than the outside, and oil discharge is not hindered. The ventilation passage 52 (FIGS. 8 and 9) that opens to the left outer surface 14h is covered at the upper side by a ridge 14i provided integrally with the upper housing 14U, and oil splashes from the ventilation passage 52 to the balancer housing 14 It is prevented from entering inside.

  As shown in FIG. 10 which is an enlarged view of a portion X in FIGS. 3 and 3, the width in the left-right direction of the first chamber 31 is different from that in the rear portion where the first oil discharge passage 41 is formed. The oil is narrower than that of the first helical gear 13e of the input shaft 13 so that the oil scraped up from the first oil discharge passage 41 is difficult to escape. That is, a pair of first discharge passage side walls 53 (53L) in which the wall sandwiching the first helical gear 13e from the left and right cooperates with the first discharge passage peripheral bottom wall 42 to define the first oil discharge passage 41 in a groove cross-sectional shape. 53R).

  As shown in FIG. 8, when the lower balancer shaft 12 </ b> L is viewed in the axial direction, the first discharge passage side wall 53 is the first rib in the range from the second rib 46 including the first oil discharge passage 41 to the first rib 45. From the discharge path peripheral bottom wall 42 toward the inside in the radial direction, it is formed with a height that sandwiches at least the tooth tip portion of the first helical gear 13e from both sides in the thrust direction.

  Returning to FIG. 3, the second chamber 32 collectively accommodates the first helical gears 12 </ b> Ld and 12 </ b> Ud of the balancer shafts 12 </ b> L and 12 </ b> U and the left balancer weights 12 </ b> Lc and 12 </ b> Uc as described above. Accordingly, there is no shaft support wall between the first helical gear 12Ud of the upper balancer shaft 12U and the balancer weight 12Uc on the right side thereof.

  On the other hand, a wall protruding from the inner surface of the balancer housing 14 is formed between the first helical gear 12Ld of the lower balancer shaft 12L and the right balancer weight 12Lc. Due to the presence of this wall and the second bearing wall 27, the oil scooped up by the teeth of the first helical gear 12 </ b> Ld is difficult to escape from the second oil discharge passage 47. That is, as shown in FIG. 10, a pair of walls that sandwich the first helical gear 12Ld from the left and right cooperate with the second discharge path peripheral bottom wall 48 to define the second oil discharge path 47 in a groove cross-sectional shape. It becomes the 2nd discharge path side wall 54 (54L, 54R). The left second discharge passage side wall 54 </ b> L is integrally formed with the second bearing wall 27 in the thickness direction, and the right second discharge passage side wall 54 </ b> R is an inner surface of the balancer housing 14 that forms the inner peripheral surface of the second chamber 32. Thus, the two main surfaces are independently formed to be free surfaces.

  As shown in FIG. 9, the second discharge passage side wall 54 is radially inward from the second discharge passage peripheral bottom wall 48 in a range from the second rib 46 to the first rib 45 including the second oil discharge passage 47. , The height is such that at least the tooth tip portion of the first helical gear 12Ld is sandwiched from both sides in the thrust direction.

  As shown in FIG. 2, the communication passage 35 is formed so as to also penetrate the right second discharge passage side wall 54 </ b> R formed independently to the right of the first helical gear 12 </ b> Ld of the lower balancer shaft 12 </ b> L. . Accordingly, the oil can freely move between the first chamber 31 and the third chamber 33.

  As shown in FIG. 10, the first helical gear 13e of the input shaft 13 and the first helical gear 12Ld of the lower balancer shaft 12L rotate in the direction of the white arrow, and the oil swept up by the teeth is held in the tooth gap. By rotating, the oil is conveyed upward in the oil discharge paths 41 and 47. The first helical gears 13e and 12Ld are formed of a pair of discharge passage side walls 53L, 53R, 54L, and 54R sandwiching each from the thrust direction, and the right discharge passage side walls 53R and 54R whose tooth gaps are on the rear side in the rotational direction. The gaps g2 and g4 are disposed at positions smaller than the gaps g1 and g3 with the left discharge passage side walls 53L and 54L.

  By configuring the oil discharge structure of the first chamber 31 to the third chamber 33 in this way, the oil is discharged to the outside as follows.

  First, as shown in FIG. 2, since the communication passage 35 communicating with the first chamber 31 to the third chamber 33 is formed, the oil flowing into the first chamber 31 to the third chamber 33 is communicated with the communication passage 35. The first helical gears 13e and 12Ld of the input shaft 13 and the lower balancer shaft 12L are gathered via the 35. The collected oil is scraped up by the teeth of the first helical gears 13e and 12Ld of the input shaft 13 or the lower balancer shaft 12L in the extending portion 31a of the first chamber 31 or the extending portion 32a of the second chamber 32, and the meshing portion is The oil discharge passages 41 and 47 that do not pass through are conveyed and efficiently discharged from the oil discharge holes 43 and 49 to the outside.

  Specifically, as shown in FIGS. 2 and 9, the balancer housing 14 includes a communication path 35 formed so as to penetrate at least the third bearing wall 28, and an extension portion 32 a of the second chamber 32. A second discharge path peripheral bottom wall 48 formed toward the downstream side in the rotation direction of the first helical gear 12Ld and defining a second oil discharge path 47 between the first helical gear 12Ld, and a second discharge path peripheral bottom A second oil discharge hole 49 formed in the upper portion of the wall 48 is provided. As a result, the oil collected below the first helical gear 12 </ b> Ld via the communication path 35 is transported through the second oil discharge passage 47 where the first helical gear 12 </ b> Ld does not pass through the meshing portion to the second oil discharge hole 49. Since it scrapes out, the oil in the balancer housing 14 is efficiently discharged outside.

  As shown in FIGS. 2 and 8, the communication passage 35 is also formed so as to penetrate the second bearing wall 27, and downstream from the extending portion 31 a of the first chamber 31 in the rotational direction of the first helical gear 13 e. A first drain passage circumferential bottom wall 42 that defines a first oil drain passage 41 between the first helical gear 13e and an upper portion of the first drain passage circumferential bottom wall 42. 1 oil discharge hole 43. As a result, the oil collected below the first helical gear 13e via the communication path 35 is transported through the first oil discharge passage 41 where the first helical gear 13e does not pass through the meshing portion, and is scraped out to the first oil discharge hole 43. The oil in the balancer housing 14 is efficiently discharged to the outside. Since the first helical gear 13e of the input shaft 13 has a larger diameter than the first helical gear 12Ld of the lower balancer shaft 12L, oil can be discharged more efficiently.

  When the oil collected below the first helical gears 13e and 12Ld is scraped up by the teeth of the first helical gears 13e and 12Ld, the first chamber 31 and the second chamber 32 are shown in FIGS. Since the second rib 46 is provided on the upstream side in the rotation direction of the first helical gears 13e and 12Ld with respect to the extending portions 31a and 32a, the oil is prevented from flowing back to the upper balancer shaft 12U side. The stirring resistance is reduced. Specifically, if the second rib 46 is not provided, when the teeth of the first helical gears 13e, 12Ld of the lower balancer shaft 12L enter the oil accumulated downward, the teeth disturb the oil, Since the state where the teeth of the first helical gears 13e and 12Ld are disturbed by the scattered oil (reverse flow) toward the upper balancer shaft 12U and the teeth of the first helical gears 13e and 12Ld continues, the oil agitation resistance increases. On the other hand, since the second rib 46 is provided, the second rib 46 suppresses the oil scattered below the first helical gears 13e and 12Ld, so that the oil stirring resistance is reduced.

  Further, since the second rib 46 is provided, it is possible to suppress the oil discharge efficiency from being lowered due to the occurrence of aeration. Specifically, if the second rib 46 is not provided, aeration occurs due to the teeth of the first helical gears 13e and 12Ld disturbing the oil, and air is introduced into the oil transported through the oil discharge passages 41 and 47. As a result, the oil discharge efficiency decreases. On the other hand, since the second rib 46 is provided, oil turbulence is suppressed and generation of aeration is suppressed, so that oil discharge efficiency is improved.

  The oil is held in the tooth gaps in the oil discharge passages 41 and 47 and is conveyed upward by being pushed up by the teeth. Since the oil discharge passages 41 and 47 do not go through the meshing portion of the teeth, the oil is efficiently conveyed by the teeth.

  As shown in FIGS. 8 and 9, the gap between the outer peripheral portions of the first helical gears 13e and 12Ld and the inner surface of the balancer housing 14 is the portion of the upper balancer shaft 12U in the portion corresponding to the oil discharge passages 41 and 47. It is smaller than other parts such as the periphery of the first helical gear 12Ud and the second helical gear 12Ue. For this reason, it is possible to suppress the oil scraped up from the oil discharge passages 41 and 47 by the teeth of the first helical gears 13e and 12Ld from escaping from the gaps between the outer peripheral portions of the first helical gears 13e and 12Ld and the discharge passage peripheral bottom walls 42 and 48. Is done. On the other hand, if the clearance between each of the first helical gears 13e, 12Ld and each of the discharge path peripheral bottom walls 42, 48 is small, the shear resistance of the oil increases, so that the sliding resistance against the walls of the first helical gears 13e, 12Ld is large. Become. On the other hand, in this embodiment, since the gap is large in other portions that do not correspond to the oil discharge paths 41 and 47, the sliding resistance of the first helical gears 13e and 12Ld in the portions that do not contribute to oil discharge is increased. Reduced.

  Further, as shown in FIGS. 2, 8, and 9, a pair of discharge passage side walls 53, 54 and each discharge passage are provided so as to sandwich at least the tooth tip portions of the first helical gears 13e, 12Ld from both sides in the thrust direction. The oil discharge passages 41 and 47 are defined in the groove cross-sectional shape by the peripheral bottom walls 42 and 48. Therefore, it is possible to prevent oil from escaping when the oil discharge paths 41 and 47 are conveyed. In addition, since the height of the discharge path side walls 53 and 54 is higher than the tooth height of the first helical gears 13e and 12Ld, the oil discharge paths 41 and 47 are conveyed by the teeth of the first helical gears 13e and 12Ld. Oil is prevented from escaping outside the drain passage side walls 53, 54.

  Further, as shown in FIG. 10, of the pair of discharge passage side walls 53 and 54 that sandwich the first helical gears 13 e and 12 Ld from the thrust direction, the right discharge passage side walls 53 </ b> R and 54 </ b> R whose tooth grooves are on the rear side in the rotation direction. And the first helical gears 13e and 12Ld are set to be smaller than the gaps g1 and g3 between the left discharge passage side walls 53L and 54L and the first helical gears 13e and 12Ld. Therefore, the oil pushed up by the teeth and flowing to the right is prevented from escaping from the gap between the first helical gears 13e, 12Ld and the discharge path side walls 53, 54.

  As shown in FIG. 8, a sub oil discharge hole 44 for oil replacement is formed at a position lower than the oil surface 6o in the oil pan 6 when the engine 1 is stopped in the first discharge path circumferential bottom wall 42. However, the oil conveyed through the first oil discharge passage 41 during the operation of the engine 1 receives a centrifugal force due to the rotational movement of the first helical gears 13e and 12Ld, and applies pressure to the peripheral bottom wall 42 of the first discharge passage. . Therefore, the position and size of the sub oil discharge hole 44 are set so that oil does not enter the balancer housing 14 according to the height of the oil surface 6o outside the balancer device 10 accumulated in the oil pan 6.

  As shown in FIGS. 8 and 9, the oil pushed up by the teeth in the oil discharge passages 41 and 47 is discharged to the outside through the oil discharge holes 43 and 49. At this time, the first rib 45 is formed at a position adjacent to the oil discharge holes 43 and 49 of the first chamber 31 and the second chamber 32 on the downstream side in the rotation direction of the first helical gears 13e and 12Ld. Even if the oil conveyed through the oil discharge passage by the teeth of the first helical gears 13e, 12Ld passes through the oil discharge holes 43, 49, the oil is blocked by the first rib 45, and therefore returns to the upper balancer shaft 12U side. Is suppressed.

  As described above, the oil discharge holes 43 and 49 are formed at a position higher than the oil level 6 o in the oil pan 6. On the other hand, in order to reduce the sliding resistance of the first helical gears 13e and 12Ld, the oil discharge holes 43 and 49 are preferably provided at positions where the lengths of the oil discharge paths 41 and 47 are shortened. However, when the oil discharge holes 43 and 49 are provided at such positions, the oil that has fallen on the upper surface of the balancer housing 14 flows rearward due to the inclination of the upper surface of the upper housing 14U, and the balancer housing passes through the oil discharge holes 43 and 49. 14 can flow into. In the present embodiment, since the peripheral walls 50 and 51 are formed so as to extend the oil discharge holes 43 and 49 on the outer surfaces of the discharge path peripheral bottom walls 42 and 48, the oil flowing on the upper surface of the upper housing 14U is oil. Inflow into the balancer housing 14 from the discharge holes 43 and 49 is prevented.

  On the other hand, if the height of the peripheral walls 50 and 51 is large, the length of the oil discharge holes 43 and 49 becomes long, and the pressure loss of the oil discharged from the oil discharge holes 43 and 49 increases. In the present embodiment, the cross-sectional areas of the first and second oil discharge holes 43 and 49 are larger than the corresponding lower ends of the oil discharge passages 41 and 47, and the corresponding projecting end sides of the first and second peripheral walls 50 and 51 are compared with each other. Is set large at the upper end of. Therefore, the pressure loss of the oil discharged from the oil discharge holes 43 and 49 is reduced, and the oil is efficiently discharged to the outside.

  As shown in FIG. 11 (A), when the oil in the balancer housing 14 is not discharged after the engine 1 is stopped, the oil that flows down due to gravity from the main gallery or the like is removed from the bearings of the shafts 12L, 12U, and 13. It leaks from the gap and accumulates in the balancer housing 14. If the balancer housing 14 has a structure in which oil does not flow in order to reduce oil agitation resistance, the oil level 10 o in the balancer device 10 may be higher than the oil level 6 o of the oil pan 6. When the oil is changed, only the oil in the oil pan 6 is extracted, and the oil in the balancer device 10 cannot be extracted. In the present embodiment, the sub-oil for oil replacement having a smaller area than the oil discharge holes 43 and 49 at a position lower than the oil surface 6o of the oil pan 6 when the engine 1 is stopped in the first discharge path circumferential bottom wall 42. A discharge hole 44 is formed. Therefore, as shown in FIG. 11B, when the oil is changed, the oil in the balancer device 10 is discharged from the sub-oil discharge hole 44 to the outside of the balancer device 10, and the amount of oil that cannot be removed can be reduced.

  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 balancer device 10 for an in-vehicle internal combustion engine has been described as an example. You can also.

  In the above embodiment, the input shaft 13 is provided coaxially with the lower balancer shaft 12L in order to increase the rotation of the crankshaft 2 stepwise and transmit it to the balancer shaft 12. Then, the driven sprocket 13a is formed integrally with the lower balancer shaft 12L or the upper balancer shaft 12U formed longer by the length of the input shaft 13, and the driving force of the crankshaft 2 is the lower balancer shaft 12L or the upper balancer shaft 12U. You may enter directly into. In this case, the second transmission mechanism 17 and the second bearing wall 27 may not be provided.

  In the above embodiment, helical gears are used as the gears of the second transmission mechanism 17 and the third transmission mechanism 18, but spur gears, helical gears, and the like may be used. In the above embodiment, the roller chain 15 is used for the winding-type first transmission mechanism 16, but a chain having another structure such as a silent chain may be used.

  In addition, the specific configuration, arrangement, quantity, angle, and the like of each member and part can be changed as appropriate without departing from the spirit of the present invention. On the other hand, all the elements of the balancer device 10 shown in the above embodiment are not necessarily essential, and can be selected as appropriate.

1 engine (internal combustion engine)
6 Oil Pan 6o Oil Pan Oil Level 10 Balancer Device 12L Lower Balancer Shaft 12Lc Balancer Weight 12Ld First Helical Gear 12U Upper Balancer Shaft 12Uc Balancer Weight 12Ud First Helical Gear 13 Input Shaft (Part of Lower Balancer Shaft 12L)
13e 1st helical gear 14 Balancer housing 21-25 1st-5th journal bearing 26-28 1st-3rd bearing wall 31-33 1st-3rd chamber 31a, 32a, 33a Extension part (the communication path 35 is formed) Part)
35 communication passages 42, 48 first and second discharge passage peripheral bottom walls 43, 49 first and second oil discharge holes 44 sub oil discharge holes 45 first ribs 46 second ribs 50, 29 first and second peripheral walls 53, 54 First and second discharge channel side walls

Claims (8)

A lower balancer that is horizontally disposed parallel to each other and having different axial heights, and has gears and unbalance weights that mesh with each other, and the gear teeth are driven to rotate downward from the meshing portions. A shaft and an upper balancer shaft;
A balancer housing that internally defines a chamber for accommodating at least the gear and the unbalanced weight;
The balancer housing is
A bearing wall that is formed so as to partition the chamber and supports the lower balancer shaft and the upper balancer shaft;
A communication passage formed along the axis of the lower balancer shaft so as to penetrate at least the bearing wall below the lower balancer shaft, and communicating the partitioned chamber;
When viewed from the axial direction of the lower balancer shaft, it is formed in an arc shape along the outer peripheral surface of the gear from the portion where the communication path is formed toward the downstream side in the rotational direction of the gear of the lower balancer shaft, A drain path peripheral bottom wall defining an oil drain path with the gear;
It possesses the oil discharge hole formed in the upper portion of the discharge channel peripheral bottom wall,
The balancer housing is
A gear chamber that collectively accommodates the gear and the unbalanced weight;
At least in the portion corresponding to the oil discharge passage in the axial view of the lower balancer shaft, the gear is provided so as to sandwich at least the tooth tip portion from both sides in the thrust direction, and cooperates with the bottom wall of the discharge passage. A pair of drain passage side walls defining the oil drain passage in a groove cross-sectional shape;
At least one of the pair of discharge passage side walls is formed so as to protrude from the inner peripheral surface of the gear chamber,
A balancer device for an internal combustion engine, wherein the communication passage passes through the one of the pair of discharge passage side walls . A lower balancer that is horizontally disposed parallel to each other and having different axial heights, and has gears and unbalance weights that mesh with each other, and the gear teeth are driven to rotate downward from the meshing portions. A shaft and an upper balancer shaft;
A balancer housing that internally defines a chamber for accommodating at least the gear and the unbalanced weight;
The balancer housing is
A bearing wall that is formed so as to partition the chamber and supports the lower balancer shaft and the upper balancer shaft;
A communication passage formed along the axis of the lower balancer shaft so as to penetrate at least the bearing wall below the lower balancer shaft, and communicating the partitioned chamber;
When viewed from the axial direction of the lower balancer shaft, it is formed in an arc shape along the outer peripheral surface of the gear from the portion where the communication path is formed toward the downstream side in the rotational direction of the gear of the lower balancer shaft, A drain path peripheral bottom wall defining an oil drain path with the gear;
An oil discharge hole formed in an upper portion of the discharge path peripheral bottom wall;
In the axial view of the lower balancer shaft, a gap between the outer peripheral portion of the gear and the inner surface of the balancer housing is set to be smaller than the periphery of the gear of the upper balancer shaft in a portion corresponding to the oil discharge path. A balancer device for an internal combustion engine. A lower balancer that is horizontally disposed parallel to each other and having different axial heights, and has gears and unbalance weights that mesh with each other, and the gear teeth are driven to rotate downward from the meshing portions. A shaft and an upper balancer shaft;
A balancer housing that internally defines a chamber for accommodating at least the gear and the unbalanced weight;
The balancer housing is
A bearing wall that is formed so as to partition the chamber and supports the lower balancer shaft and the upper balancer shaft;
A communication passage formed along the axis of the lower balancer shaft so as to penetrate at least the bearing wall below the lower balancer shaft, and communicating the partitioned chamber;
When viewed from the axial direction of the lower balancer shaft, it is formed in an arc shape along the outer peripheral surface of the gear from the portion where the communication path is formed toward the downstream side in the rotational direction of the gear of the lower balancer shaft, A drain path peripheral bottom wall defining an oil drain path with the gear;
An oil discharge hole formed in an upper portion of the discharge path peripheral bottom wall;
A first rib protruding from the inner surface of the balancer housing is formed at a position adjacent to the oil discharge hole on the downstream side in the rotation direction of the gear so as to reduce a gap with the outer peripheral portion of the gear. A balancer device for an internal combustion engine. A lower balancer that is horizontally disposed parallel to each other and having different axial heights, and has gears and unbalance weights that mesh with each other, and the gear teeth are driven to rotate downward from the meshing portions. A shaft and an upper balancer shaft;
A balancer housing that internally defines a chamber for accommodating at least the gear and the unbalanced weight;
The balancer housing is
A bearing wall that is formed so as to partition the chamber and supports the lower balancer shaft and the upper balancer shaft;
A communication passage formed along the axis of the lower balancer shaft so as to penetrate at least the bearing wall below the lower balancer shaft, and communicating the partitioned chamber;
When viewed from the axial direction of the lower balancer shaft, it is formed in an arc shape along the outer peripheral surface of the gear from the portion where the communication path is formed toward the downstream side in the rotational direction of the gear of the lower balancer shaft, A drain path peripheral bottom wall defining an oil drain path with the gear;
An oil discharge hole formed in an upper portion of the discharge path peripheral bottom wall;
A second rib protruding from the inner surface of the balancer housing at a position adjacent to the upstream side in the rotational direction of the gear with respect to the portion where the communication path is formed so as to reduce the gap with the outer peripheral portion of the gear. A balancer device for an internal combustion engine, characterized in that is formed. A lower balancer that is horizontally disposed parallel to each other and having different axial heights, and has gears and unbalance weights that mesh with each other, and the gear teeth are driven to rotate downward from the meshing portions. A shaft and an upper balancer shaft;
A balancer housing that internally defines a chamber for accommodating at least the gear and the unbalanced weight;
The balancer housing is
A bearing wall that is formed so as to partition the chamber and supports the lower balancer shaft and the upper balancer shaft;
A communication passage formed along the axis of the lower balancer shaft so as to penetrate at least the bearing wall below the lower balancer shaft, and communicating the partitioned chamber;
When viewed from the axial direction of the lower balancer shaft, it is formed in an arc shape along the outer peripheral surface of the gear from the portion where the communication path is formed toward the downstream side in the rotational direction of the gear of the lower balancer shaft, A drain path peripheral bottom wall defining an oil drain path with the gear;
An oil discharge hole formed in an upper portion of the discharge path peripheral bottom wall;
The balancer housing further includes a peripheral wall formed to protrude from an outer surface of the discharge path peripheral bottom wall so as to extend the oil discharge hole;
A balancer device for an internal combustion engine, wherein a cross-sectional area of the oil discharge hole is set to be larger at an end portion on the protruding end side of the peripheral wall than an end portion on the oil discharge passage side. The balancer device for an internal combustion engine according to claim 1 , wherein a height of the pair of discharge passage side walls is higher than a tooth height of the gear. The gear is a helical gear;
Among the pair of discharge path side walls, the gap between the discharge path side wall and the gear on one side where the tooth groove of the gear is located on the rear side in the rotation direction of the gear is defined as the discharge path side wall and the gear on the other side. The balancer device for an internal combustion engine according to claim 1 , wherein the balancer device is set to be smaller than a clearance between the internal combustion engine and the internal combustion engine. The balancer housing is disposed inside the oil pan;
The sub-oil discharge hole for oil change having an area smaller than the oil discharge hole is formed at a position lower than the oil level of the oil pan when the engine is stopped in the balancer housing. A balancer device for an internal combustion engine according to claim 7 .

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