JP2013122230A - Balancer device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a balancer device which can reduce the number of assembling man-hours and improve the axial center accuracy of a bearing a balancer shaft.SOLUTION: The balancer device 10 includes: driving and driven balancer shafts 11, 21; a balancer housing 30 including a lower housing 31 and an upper housing 32; a pump housing 51 which is formed integrally with one end of the lower housing 31; and a pump cover 56 forming a pump chamber 63 in cooperation with the pump housing 51. One end of the side of the pump housing 51 of the driven balancer shaft 21 is inserted into the pump chamber 63 and connected to an inner rotor 61, one end of the driving balancer shaft 11 having a small sprocket 7 provided therein is protruded from the balancer housing 30, and both the balancer shafts 11, 21 are pivoted on only the balancer housing 30 and the pump housing 51.

Description

  The present invention relates to a balancer device for an internal combustion engine in which a pump housing is integrally formed with a balancer housing that supports a balancer shaft.

  In a reciprocating engine (hereinafter simply referred to as an engine) mounted on an automobile or the like, two balancer shafts each having a balancer weight (counter weight) are provided below the crankshaft in order to cancel the secondary vibration generated by the piston. The drive balancer shaft is rotated by the rotation of the crankshaft transmitted through the power transmission mechanism, and the driven balancer shafts linked with each other by gears are rotated at the same speed in the opposite direction. A balancer device adapted to be driven is generally installed.

  The balancer device may be integrally provided with an oil strainer, an oil pump, and a suction passage that connects the oil strainer and the oil pump. As such a balancer device, the balancer housing that supports the balancer shaft is composed of an upper housing and a lower housing that are divided into upper and lower planes passing through the axis of both balancer shafts, and an end face of the pump housing that is integrally formed with the lower housing The present applicant has proposed that a pump chamber is formed by attaching an oil pump (oil pump rotor) to the end of the driven balancer shaft protruding from the shaft and joining a pump cover to the end face of the pump housing (patent) Reference 1).

Japanese Patent No. 3643506

  By the way, in the balancer device of patent document 1, the pump chamber which accommodates an oil pump rotor is formed in the pump cover side, and it supports the shaft part (cylindrical extension part of an inner rotor) which protrudes through an inner rotor, and an outer rotor. A bearing is formed on the pump cover. The drive balancer shaft on the opposite side of the driven balancer shaft provided with the oil pump protrudes from the pump cover, and the driven cam sprocket is fixed to the end of the pump balancer shaft. A bearing for supporting this is formed. Thus, when the common shaft bearing is formed in different members (pump cover and balancer housing), it is difficult to align the axes so that there is no misalignment. For this reason, in order to increase the shaft center accuracy, it is necessary to perform co-processing of drilling the bearing hole in a state where the pump cover is assembled to the balancer housing.

  However, even if the bearing is formed by co-processing, in order to provide the oil pump in the pump chamber, it is necessary to remove the once-assembled pump cover from the balancer housing, which increases the number of assembly steps. Also, if the pump cover is removed to assemble the oil pump, the balancer housing cannot be fixed at the co-working position even if the positioning pin is used when the pump cover is reassembled. Accuracy is reduced. A decrease in axial center accuracy is not preferable because it causes seizure and galling.

  The present invention has been devised to solve the problems included in the prior art, and provides a balancer device capable of reducing the number of assembling steps and improving the shaft center accuracy of the bearing of the balancer shaft. For the purpose.

  In order to solve such a problem, according to one aspect of the present invention, a driving and driven balancer each having a balancer weight (12, 22) and linked so as to rotate at the same speed in opposite directions. A lower housing (31) having a shaft (11, 21), a bearing lower half (33) for supporting both the balancer shafts in parallel with each other, and a bearing (41 in cooperation with the bearing lower half) To 44) and an upper housing (32) which is combined with the lower housing to form a balancer housing (30), and one of the lower and the upper housing (31). A pump housing (51) integrally formed at one end in the axial direction and defining at least a part of a pump chamber (63) containing an oil pump (60); A balancer device for an internal combustion engine (1) having a pump cover (56) which is assembled to the pump housing from the outside in the axial direction and forms the pump chamber in cooperation with the pump housing and constitutes the pump body (64). 10) The one end of the driven balancer shaft on the pump housing side enters the pump chamber and is connected to the oil pump, and the one end of the driving balancer shaft on the pump housing side is the balancer housing. The torque input means protrudes outward and is driven by a crankshaft (2), and both the balancer shafts are supported by only the balancer housing (30) and the pump housing (51).

  According to this configuration, since the bearings of both balancer shafts are not formed on the pump cover, it is not necessary to assemble the pump cover to the balancer housing before processing the bearings, and the number of assembly steps can be reduced. Further, since the half bearing is formed only in the balancer housing, the shaft center accuracy is not lowered by reassembly, so that the shaft center accuracy can be increased. Therefore, the clearance of the bearing portion can be reduced, and the discharge amount of the oil pump can be prevented from decreasing due to oil leak from the bearing portion.

  According to another aspect of the present invention, the pump housing includes the oil pump, and the oil pump is supported by the pump housing alone.

  According to this configuration, the oil pump rotor can be pivotally supported without forming a bearing on the pump cover. Therefore, even if the pump cover is reassembled, the shaft center of the oil pump and the shaft center of the driven balancer shaft are not misaligned.

  Further, according to one aspect of the present invention, the bearing (42) closest to the torque input means of the driving balancer shaft is more than the bearing (44) closest to the oil pump of the driven balancer shaft. It can be set as the structure offset to the torque input means side.

  According to this configuration, the driven balancer shaft can be pivotally supported at a position closer to the torque input means, and the support rigidity of the driven balancer shaft can be increased while preventing a decrease in axial center accuracy due to reassembly. it can.

  According to another aspect of the present invention, the pump housing has a lateral extension (52) formed in the lower housing and defining an oil passage (69) of the oil pump therein. The lower half portion (33) of the bearing (42) closest to the torque input means of the drive balancer shaft may be formed above the laterally extending portion.

  According to this configuration, the bearing lower half portion of the bearing of the drive balancer shaft can be formed at the portion where the balancer housing and the pump body are connected, so that the support rigidity can be increased.

  According to another aspect of the present invention, the balancer housing is configured to expose the driven balancer shaft between the pump housing and the pump housing pivotally supports the driven balancer shaft. It can be set as the structure which has a bearing hole (3rd bearing 45).

  According to this configuration, the balancer housing can be reduced in weight, and the driven balancer shaft can be pivotally supported also in the pump housing integrally formed with the balancer housing, so that the driving load of the oil pump can be reliably supported. it can.

  Also, according to one aspect of the present invention, the balancer weight of the driven balancer shaft is divided into two in the axial direction across the journal portion (24) supported by the bearing (43), and both the balancer weights The bearing wall (48) between (22l, 22r) constitutes a thrust bearing of the driven balancer shaft, and the bearing (42, 44) of the driven balancer shaft is a bearing wall (48 between the balancer weights). ) And the shaft end wall (49) on the pump housing side, and the driven balancer shaft (21) is connected to each other by a joint (27) provided between the balancer housing and the pump housing. The weight shaft (21a) on both the balancer weights and the pump shaft (21b) on the oil pump side. The joint may be configured to have a key (27a) and keyway (27b) extending in a direction perpendicular to the axial direction.

  According to this configuration, when assembling the balancer device, the driven balancer shaft can be assembled simply by placing the weight shaft on the half bearing so that the key and the key groove engage with each other with the pump shaft disposed. As a result, assembly is improved.

  Thus, according to the present invention, it is possible to provide a balancer device that can reduce the number of assembling steps and can improve the axial center accuracy of the bearing of the balancer shaft.

Sectional drawing which shows the engine lower part which concerns on embodiment along a drive balancer shaft Sectional view along the line II-II in FIG. Sectional view of driven balancer shaft along line III-III in FIG. 1 is an exploded perspective view of the balancer device shown in FIG. The right side view of the balancer apparatus seen along the VV line in FIG. Bottom view of the balancer device shown in FIG. The perspective view which looked at the balancer apparatus shown in FIG. 1 from the bottom face side Partial sectional view taken along line VIII-VIII in FIG. Graph showing misalignment by the balancer device shown in FIG.

  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. In the following description, the direction is indicated based on the arrow shown in FIGS. 1 and 2 according to the traveling direction of the automobile in a state where the engine 1 is mounted. 3 to 8, in order to facilitate understanding, the cylinder axis direction and the direction orthogonal thereto are shown as up and down and front and rear with reference to the balancer device 10.

  As shown in FIGS. 1 and 2, the engine 1 is an in-line four-cylinder engine in which a crankshaft 2 extends in the horizontal direction, and includes a lower block 3, an oil pan 4, a balancer device 10, and the like. The cylinder axis is tilted rearward and mounted on the automobile.

  The balancer device 10 is for reducing the secondary vibration of the engine 1 caused by the reciprocating motion of the piston, and as shown in FIGS. 3 and 4, the center of gravity extends radially outward from the center of rotation. A drive balancer shaft 11 and a driven balancer shaft 21 which are provided with front and rear balancer weights 12 and 22 having substantially the same shape and whose positions are biased, and these two balancer shafts 11 and 21 are parallel to each other. And a balancer housing 30 for supporting and accommodating. The balancer housing 30 includes a lower housing 31 and an upper housing 32 that are divided into two vertically along a plane passing through the axis of the balancer shafts 11 and 21. The balancer device 10 has a lower surface of the lower block 3 (below the crankshaft 2) in a state of being enclosed in the oil pan 4 by a through bolt inserted from below into a bolt insertion hole 16 (see FIG. 4) provided at an appropriate position. To be concluded.

  As shown in FIG. 1, the crankshaft 2 is provided with a crank pulley 5 at the right end, and a large sprocket 6 is fixed to the back side thereof. A small sprocket 7 is bolted to the right end of the drive balancer shaft 11 disposed on the front side, and the crankshaft 2 transmitted via a link chain 8 spanned between the large and small sprockets 6, 7. The drive balancer shaft 11 is rotationally driven by the rotational force. As shown in FIGS. 1, 3, and 4, the balancer shafts 11 and 21 are coupled to each other by helical gears 13 and 23 that are integrally coupled to the balancer shafts 11 and 21. The drive balancer shaft 11 is rotationally driven in the same direction as the crankshaft 2 at a rotational speed twice that of the crankshaft 2. The driven balancer shaft 21 is rotationally driven at an equal speed in the opposite direction to the drive balancer shaft 11 by the meshing of the helical gears 13 and 23.

  The two balancer shafts 11 and 21 have first journal portions 14 and 24 having a relatively large diameter on the left side of the helical gears 13 and 23, and second journal portions 15 and 25 having a relatively small diameter on the right side of the helical gears 13 and 23. Are formed respectively. Further, the balancer weights 12 and 22 are divided into left and right (axial direction) with the first journal portions 14 and 24 interposed therebetween to form left and right balancer weight portions 12l, 12r, 22l and 22r, and the same in the axial direction. The balancer shafts 11 and 21 are integrally formed at the positions.

  The lower housing 31 is formed with two lower bearing halves 33 for both the balancer shafts 11 and 21, and the upper housing 32 is also formed with two bearing upper halves 34 for both the balancer shafts 11 and 21. Has been. The lower half portion 33 and the upper half portion 34 of the bearing are formed by joining the lower and upper housings 31 and 32 to each other so that the corresponding members cooperate with each other and the balancer shafts 11 and 21 are divided into two parts. The bearings 41 and 43 and the second bearings 42 and 44 are configured. The first and second journal portions 14, 15, 24, 25 of the balancer shafts 11, 21 are supported by the first and second bearings 41, 42, 43, 44 thus configured.

  The both balancer shafts 11 and 21 are formed with flange portions having diameters enlarged at opposite end portions sandwiching the first journal portions 14 and 24 in the left and right balancer weight portions 12l, 12r, 22l and 22r, respectively. The mutually opposing end surfaces of the parts form a thrust receiving surface. That is, the first bearing walls 46 and 48 that respectively constitute the first bearings 41 and 43 and support the first journal portions 14 and 24 also serve as thrust bearings for the balancer shafts 11 and 21. Therefore, it is not necessary to separately form a thrust bearing or a thrust receiving surface on the lower or upper housings 31 and 32 or both balancer shafts 11 and 21, and the structure can be simplified and the weight can be reduced. The first bearing walls 46 and 48 that support the balancer shafts 11 and 21 are provided at the same position in the left-right direction and are connected in the front-rear direction.

  A state in which the first and second journal portions 14, 15, 24, 25 of the balancer shafts 11, 21 are placed on the bearing lower half portion 33 on the lower housing 31 side in each of the bearings 41 to 44 (state of FIG. 4). Then, after aligning the upper half portion 34 of the bearings 41 to 44 on the upper housing 32 side with the journal portions 14, 15, 24, 25 of the balancer shafts 11, 21, the lower and upper housings 31, 32 are arranged. By joining together, both balancer shafts 11 and 21 are rotatably accommodated in the lower and upper housings 31 and 32. The first bearing walls 46 and 48 forming the first bearings 41 and 43 are in sliding contact with the opposing end surfaces of the left and right balancer weight portions 12l, 12r, 22l and 22r to receive the thrust force.

  The lower and upper housings 31 and 32 are formed such that the rear side portion that accommodates the driven balancer shaft 21 is relatively short in the axial direction, and the front side portion that accommodates the drive balancer shaft 11 is relatively long in the axial direction. The right end wall of the front side portion that accommodates the drive balancer shaft 11 is configured to be located on the right side of the right end wall of the portion that accommodates the driven balancer shaft 21. And the 2nd bearings 42 and 44 of both the balancer shafts 11 and 21 are formed in each right end wall (henceforth the 2nd bearing walls 47 and 49) of the part which accommodates the balancer shafts 11 and 21 corresponding. Yes. Accordingly, the second bearing 42 of the drive balancer shaft 11 is provided on the right side of the second bearing 44 of the driven balancer shaft 21, that is, at a position offset to the small sprocket 7 side, and from the corresponding first bearings 41, 43. The distance is longer than that of the driven balancer shaft 21.

  The lower and upper housings 31 and 32 are connected to the first bearing walls 46 and 48 and the second bearing walls 47 and 49 to surround the right balancer weight portions 12r and 22r and the helical gears 13 and 23 from the radial direction. A shaft surrounding wall 35 that protrudes leftward from the first bearing walls 46 and 48 and surrounds the left balancer weight portions 12l and 22l from the radial direction is integrally formed.

  As shown in FIGS. 3 and 4, the balancer device 10 is integrally provided with a trochoid oil pump 60 for pumping oil to various parts of the engine, and the driven balancer shaft 21 is provided with the oil pump 60. Rotating drive. Specifically, at the right end of the lower housing 31, a pump housing 51 that defines a part of a cylindrical pump chamber 63 containing the oil pump 60 protrudes above the mating surface 30 a with the upper housing 32. The pump cover 56 assembled to the pump housing 51 from the right side is bolted to the right end surface of the pump housing 51, and the pump housing 51 and the pump cover 56 cooperate to form a pump chamber 63. In addition, a pump body 64 is configured. The oil pump 60 includes an inner rotor 61 connected to the right end of the two-chamfered driven balancer shaft 21 and an outer rotor 62 pivotally supported on the outer peripheral wall of the pump chamber 63. When the driven balancer shaft 21 rotates, The oil in the oil pan 4 is sucked and pumped to various parts of the engine.

  The pump housing 51 extends to the right end of the driven balancer shaft 21 so as to contain the oil pump 60 and forms an outer peripheral surface of the pump chamber 63, and forms a bearing for the outer rotor 62. Further, the pump housing 51 is provided at a position spaced to the right side from the rear portion of the balancer housing 30 that houses the driven balancer shaft 21. Therefore, the driven balancer shaft 21 is exposed between the balancer housing 30 and the pump housing 51.

  As shown in FIG. 4, the pump housing 51 cooperates with the pump cover 56 to project forward through the lower part of the drive balancer shaft 11 so as to define the discharge passage 69 of the oil pump 60 therein. The extension portion 52 and the second lateral extension portion 53 projecting rearward in cooperation with the pump cover 56 to define the downstream portion of the suction passage 68 of the oil pump 60 inside. The first lateral extension 52 is integrally formed at the lower part of the front end of the lower housing 31 (the second bearing 42 of the drive balancer shaft 11). That is, the lower bearing half 33 of the second bearing 42 of the drive balancer shaft 11 is formed above the first lateral extension 52. On the other hand, the second laterally extending portion 53 is integrally formed on the rear side of the lower housing 31 via a plate-like connecting portion 36 (see FIG. 6) formed on the rear side of the lower housing 31 and reinforced with ribs. The

  As shown in FIG. 5, the pump cover 56 has a joint surface 56 a corresponding to the right end surface of the pump housing 51, defines the right side surface of the pump chamber 63, and also includes a discharge passage 69 and a suction passage of the oil pump 60. The downstream portion of 68 is formed in cooperation with the pump housing 51. A valve chamber 70 is formed below the pump chamber 63 so as to communicate the discharge passage 69 and the suction passage 68. The valve chamber 70 is a known plunger valve that is slidably fitted into the valve chamber 70. A surplus pressure in the discharge passage 69 is returned to the suction passage 68 by a relief valve (not shown). Bolt boss portions 57 that form bolt insertion holes 16 (see FIG. 6) for fastening to the lower block 3 are provided at the front and rear portions of the pump cover 56 so as to form the upper surface of the balancer device 10. A through hole 58 having a diameter larger than the shaft diameter of the right end portion of the drive balancer shaft 11 and through which the drive balancer shaft 11 is inserted without being pivotally supported is formed in a portion through which the drive balancer shaft 11 passes.

  The lower housing 31 and the pump housing 51, the upper housing 32, and the pump cover 56 integrally formed with the lower housing 31 are all die-cast products made of an aluminum alloy, and are downstream of a tubular passage 67 and a suction passage 68 of the lower housing 31, which will be described later. The valve chamber 70 of the pump cover 56 and the like are formed using a core.

  As shown in FIG. 3, the driven balancer shaft 21 is formed with a third journal portion 26 having a smaller diameter than the second journal portion 25 on the right side with a gap further from the second journal portion 25. The third journal portion 26 is pivotally supported by a third bearing 45 including a bearing hole formed so as to penetrate the vertical wall of the pump housing 51. The driven balancer shaft 21 has a left end that enters the pump chamber 63 and is connected to the inner rotor 61 to drive the oil pump 60.

  As shown in FIG. 4, the driven balancer shaft 21 is a joint 27 disposed at an exposed portion between the balancer housing 30 and the pump housing 51 (between the second bearing 44 and the third bearing 45). Thus, it is divided into two in the axial direction. Hereinafter, the driven balancer shaft 21 on the balancer weight 22 side having the left and right balancer weight portions 22l and 22r is referred to as a weight shaft 21a, and the driven balancer shaft 21 on the oil pump 60 side is referred to as a pump shaft 21b. The joint 27 includes a key 27a formed at the right end of the weight shaft 21a so as to extend in a direction orthogonal to the axial direction, and a key groove 27b formed at the left end of the pump shaft 21b. As a result, the weight shaft 21a is fitted so that the key 27a is fitted in the key groove 27b in a state where the upper housing 32 is not yet assembled to the lower housing 31 and the pump shaft 21b is pivotally supported by the third bearing 45. The driven balancer shaft 21 in which the pump shaft 21b and the weight shaft 21a are connected to each other is assembled to the lower housing 31 only by being mounted on the bearing lower half 33 of the first and second bearings 43 and 44 from above (see FIG. 4 state).

  On the other hand, as shown in FIG. 1, the drive balancer shaft 11 has a left end on the pump housing 51 side that protrudes outward from the balancer housing 30 and the first lateral extension 52 of the pump housing 51 and passes through the through hole 58. The left end face of the pump cover 56 protrudes to the left, and the small sprocket 7 is bolted to the left end face. When the drive balancer shaft 11 is assembled to the lower housing 31, the opposing surfaces of the left and right balancer weight portions 12l and 12r form a thrust receiving surface as described above, so that the drive balancer shaft 11 is shifted in the axial direction to a predetermined position. Cannot be placed. Therefore, if the bearing of the drive balancer shaft 11 is formed on the pump cover 56, the drive balancer shaft 11 cannot be assembled / removed when the pump cover 56 is assembled. On the other hand, in the present invention, since the pump cover 56 does not support the drive balancer shaft 11, if the through hole 58 of the pump cover 56 is formed large, the drive balancer shaft 11 even when the pump cover 56 is assembled. Can also be assembled or removed.

  Since the balancer housing 30, the pump housing 51, and the pump cover 56 are configured in this way, both the balancer shafts 11 and 21 are pivotally supported only by the balancer housing 30 and the pump housing 51.

  As shown in FIGS. 2, 3, and 6, the bottom wall of the balancer housing 30 is provided so as to extend downward in order to attach a strainer cover 71 that holds an oil strainer (not shown) to the suction port 71a. A cylindrical wall-shaped strainer mounting portion 37 is integrally formed. The strainer mounting portion 37 is centered below the driven balancer shaft 21 disposed at the lower position of the balancer shafts 11 and 21, and the left side portion is connected to the first bearing wall 48 of the driven balancer shaft 21. Placed in position. The strainer mounting portion 37 has a bottomed recess 65 formed therein with the shaft surrounding wall 35 of the lower housing 31 formed in an arc shape along the rotation locus of the balancer weight 22.

  As shown in FIG. 2, at a position adjacent to the rear side of the strainer mounting portion 37 (a side with respect to both the balancer shafts 11 and 12), the plate-like connecting portion 36 is connected to the shaft surrounding wall 35. The tubular wall 38 connected to (FIG. 6) is integrally formed with the lower housing 31 so as to be positioned between the mating surface 30a of the lower housing 31 with the upper housing 32 and the lower end surface 30b. The tubular wall 38 extends along the driven balancer shaft 21 through a position away from the bottomed recess 65 so as to leave the partition wall 39 between the bottomed recess 65 and a circular shape reaching the right end surface of the lower housing 31. A tubular passage 67 having a cross section is provided linearly. The tubular passage 67 forms an upstream portion of the suction passage 68 from the oil strainer to the oil pump 60, and as shown in FIG. 7, the suction passage 68 formed in the second lateral extension 53 of the pump housing 51. Connect to the downstream part.

  As shown in FIGS. 7 and 8, the partition wall 39 that separates the bottomed recess 65 and the tubular passage 67 is formed so that two circular cross-sectional passages 66 that communicate with each other are aligned in the axial direction of the tubular passage 67. Has been. As described above, the lower housing 31 is die-cast, and the bottomed recess 65 and the tubular passage 67 are formed by die casting at the time of die casting, while the circular cross-section passage 66 is formed by drilling after die casting.

  As shown in FIGS. 6 and 7, there are two bolt insertion holes 16 for fastening the balancer device 10 to the lower block 3 before and after the pump cover 56 and before and after the first bearing walls 46 and 48 as described above. And a total of five are formed outside the end of the discharge passage 69 (see FIG. 4) formed in the upper housing 32 (connection portion with the lower block 3). Among these, the bolt boss portion 17 that forms the bolt insertion hole 16 outside the terminal end of the discharge passage 69 is formed to be relatively thin, and is reinforced by the rib 18 connected to the shaft surrounding wall 35. On the other hand, the bolt boss portions 17 that form the bolt insertion holes 16 before and after the first bearing walls 46 and 48 are formed with a comparatively thick bottom because they require the greatest rigidity. And the rib 18 connected to the strainer attachment part 37 is connected to the bolt boss part 17 on the rear side among these, and the fastening strength of the balancer housing 30 is further improved.

  When the oil pump 60 rotates together with the driven balancer shaft 21, the oil flowing from the oil strainer through the bottomed recess 65, the circular cross-section passage 66 and the tubular passage 67 into the pump body 64 is pressurized by the oil pump 60 and discharged. It is discharged into the passage 69. The pressure is fed from the end of the discharge passage 69 opened on the upper surface of the balancer housing 30 to the oil supply passage in the lower block 3 and supplied to each part of the engine.

  Thus, the balancer shafts 11 and 21 are pivotally supported only by the balancer housing 30 and the pump housing 51, so that the pump cover 56 is mounted on the balancer housing 30 before the bearings 41 to 44 of the balancer shafts 11 and 21 are processed. There is no need to assemble it, and assembly man-hours are reduced. Further, since the half bearings 41 to 44 are formed only in the balancer housing 30, the shaft center accuracy is not lowered by reassembly, so that high shaft center accuracy can be realized. That is, the axial center accuracy can be determined only by the accuracy at the time of machining. Thereby, since the clearance of the bearing portion can be reduced, it is possible to prevent the discharge amount of the oil pump 60 from being reduced due to the oil leak from the bearing portion.

  Further, since the drive balancer shaft 11 is pivotally supported only by the two bearings 41 and 42 formed in the balancer housing 30, the load applied to the second bearing 42 located in the vicinity of the small sprocket 7 is reduced. That is, as shown in FIG. 9B, another bearing is provided between the first and second bearings 41 and 42 of the above-described embodiment (for example, a position corresponding to the second bearing 44 of the driven balancer shaft 21). In the case of the comparative example in which the third bearing 143 is formed (hereinafter referred to as the third bearing 143), the second bearing 42 to which the link chain tension P1 is applied is opposite to the load P2 of the right balancer weight portion 12r supported by the third bearing 143. As much force is applied, the load and friction are larger than those of the second bearing 42 of the present embodiment shown in FIG.

In other words, in the present embodiment shown in FIG. 9A, the balance of force with the first bearing 41 to which the bearing reaction force Qrc is applied as a fulcrum can be expressed as the following equation (1).
Qra · l1 + P2 · L2 = P1 · L1 + P3 · L3 (1)
Qra: bearing reaction force of the second bearing 42, P1: tension of the link chain 6, P2: centrifugal force of the right balancer weight portion 12r, P3: centrifugal force of the left balancer weight portion 12l.
Therefore, the bearing reaction force Qra of the second bearing 42 is represented by the following expression (2).
Qra = (P1 / L1 + P3 / L3-P2 / L2) / l1 (2)
On the other hand, in the comparative example shown in FIG. 9B, the balance of force with the first bearing 41 as a fulcrum can be expressed as the following equation (3).
Qra · l1 + P2 · L2 = P1 · L1 + P3 · L3 + Qrb · l2 (3)
Where Qrb is the bearing reaction force of the third bearing 143.
Therefore, the bearing reaction force Qra of the second bearing 42 is expressed by the following expression (4).
Qra = (P1 · L1 + P3 · L3 + Qrb · l2−P2 · L2) / l1 (4)
Here, the centrifugal forces P3 and P2 of the left and right balancer weight portions 12l and 12r are the same, and the distances L2 and L3 from the respective first bearings 41 are also the same. The bearing reaction force Qra of the second bearing 42 and the bearing reaction force Qra of the second bearing 42 of the comparative example are expressed by the following equations (5) and (6), respectively.
Qra = (P1 · L1) / l1 (5)
Qra = (P1 · L1 + Qrb · l2) / l1 (6)
Therefore, the bearing reaction force Qra of the second bearing 42 of the present embodiment is smaller than the bearing reaction force Qra of the second bearing 42 of the comparative example by an amount corresponding to the bearing reaction force Qrb supported by the third bearing 143. As a result, the second bearing 42 that supports the drive balancer shaft 11 is reduced in load and can be reduced in diameter and weight.

  On the other hand, in the present embodiment, the bearing reaction force Qra of the second bearing 42 is reduced, while the bearing reaction force Qrc of the first bearing 41 is increased. Therefore, in the present embodiment, the first bearing 41 is configured to have a wide and high rigidity, and a device is added to the lubricating oil passage. That is, conventionally, in order to lubricate the bearing portion that supports both balancer shafts between the left and right balancer weight portions, oil from one side of the balancer housing to the bearing of the other balancer shaft via the bearing of one balancer shaft. Since the path was formed, the upstream bearing could be sufficiently lubricated, but if oil leakage occurred on the upstream side, the lubrication of the downstream bearing could be relatively reduced. Therefore, in the present embodiment, as shown in FIG. 4, both the balancer shafts 11 in the first bearing walls 46 and 48 among the bolt insertion holes provided in the upper housing 32 for fastening the upper housing 32 to the lower housing 31. , 21 is also used as a passage for lubricating oil, and the lubricating oil supplied between the balancer shafts 11, 21 is distributed back and forth to lubricate both balancer shafts 11, 21 evenly. I can do it.

  In the present embodiment, the pump housing 51 includes the oil pump 60, and the oil pump 60 is pivotally supported only by the pump housing 51, so that the outer rotor 62 can be pivotally supported without forming a bearing on the pump cover 56. Therefore, even if the pump cover 56 is reassembled, the shaft center of the outer rotor 62 and the shaft center of the driven balancer shaft 21 do not cause misalignment.

  In the present embodiment, the second bearing 42 on the drive balancer shaft 11 closest to the smallest sprocket 7 is smaller than the second bearing 44 that is the half bearing on the oil pump 60 side of the driven balancer shaft 21. Since it is offset to the side, the driven balancer shaft 21 is pivotally supported at a position closer to the small sprocket 7 and its supporting rigidity is increased.

  On the other hand, the pump housing 51 formed integrally with the lower housing 31 has a first lateral extension 52 that internally defines a discharge passage 69 of the oil pump 60, and is located on the smallest sprocket 7 side of the drive balancer shaft 11. Since the lower bearing half 33 of the second bearing 42 is formed above the first lateral extension 52, the second bearing 42 of the drive balancer shaft 11 is connected to the portion where the balancer housing 30 and the pump body 64 are connected. Therefore, the support rigidity of the drive balancer shaft 11 is high.

  Furthermore, the balancer housing 30 is configured to expose the driven balancer shaft 21 between the pump housing 51 and the pump housing 51 includes a third bearing 45 including a bearing hole that pivotally supports the driven balancer shaft 21. As a result, the balancer housing 30 is reduced in weight, and the driven balancer shaft 21 is also pivotally supported by the pump housing 51 formed integrally with the balancer housing 30, so that the driving load of the oil pump 60 is reliably supported. The

  In the present embodiment, the balancer weights 12 and 22 of the balancer shafts 11 and 21 are divided into two in the axial direction across the first journal portions 14 and 24 supported by the first bearings 41 and 43, and the first Since the bearing walls 46 and 48 serve as thrust bearings for the balancer shafts 11 and 21, the balancer device 10 can be simplified and reduced in weight. As described above, the driven balancer shaft 21 has the joint 27 and the weight shaft 21a. Since the pump shaft 21b is divided, not only the drive balancer shaft 11 but also the driven balancer shaft 21 is assembled, the weight shaft so that the key 27a and the key groove 27b are engaged with each other with the pump shaft 21b disposed. Lower housing only by placing 21a on lower bearing portion 33 of lower housing 31 It is possible to assemble the 1, assembling property is improved.

  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 embodiment, the balancer device 10 of the present invention is applied to an in-line four-cylinder gasoline engine, but it can also be applied to other internal combustion engines. In addition, the specific configuration, arrangement, and quantity of each device and member can be changed as appropriate without departing from the spirit of the present invention. On the other hand, all the components of the balancer device 10 according to the present invention shown in the above-described embodiment are not necessarily essential, and can be appropriately selected as long as they do not depart from the gist of the present invention.

1 Engine 2 Crankshaft 7 Small sprocket (torque input means)
DESCRIPTION OF SYMBOLS 10 Balancer device 11 Drive balancer shaft 12 Balancer weight 21 Driven balancer shaft 21a Weight shaft 21b Pump shaft 22 Balancer weight 22l Left balancer weight portion 22r Right balancer weight portion 24 First journal portion 27 Joint 27a Key 27b Key groove 30 Balancer housing 31 Lower housing 32 Upper housing 33 Bearing lower half 34 Bearing upper half 41 First bearing (for drive balancer shaft 11)
42 Second bearing (for drive balancer shaft 11)
43 1st bearing (for driven balancer shaft 21)
44 Second bearing (for driven balancer shaft 21)
45 3rd bearing (bearing hole for driven balancer shaft 21)
48 1st bearing wall (for driven balancer shaft 21)
49 Second bearing wall (for driven balancer shaft 21)
51 Pump housing 52 First lateral extension 56 Pump cover 60 Oil pump 63 Pump chamber 64 Pump body 69 Discharge passage

Claims (6)

Drive and driven balancer shafts, each having a balancer weight and linked to rotate at equal speeds in opposite directions;
A lower housing having a bearing lower half for pivotally supporting the balancer shafts in parallel with each other;
An upper housing that has a bearing upper half that forms a bearing in cooperation with the bearing lower half, and that forms a balancer housing in combination with the lower housing;
A pump housing integrally formed at one end in the axial direction of one of the lower and upper housings and defining at least a part of a pump chamber containing an oil pump;
A balancer device for an internal combustion engine that is assembled to the pump housing from the outside in the axial direction, and has a pump cover that forms the pump chamber in cooperation with the pump housing and constitutes a pump body,
One end of the driven balancer shaft on the pump housing side enters the pump chamber and is connected to the oil pump,
One end of the drive balancer shaft on the pump housing side protrudes out of the balancer housing and has torque input means driven by a crankshaft,
The balancer device for an internal combustion engine, wherein both the balancer shafts are supported by only the balancer housing and the pump housing.   The balancer device for an internal combustion engine according to claim 1, wherein the pump housing includes the oil pump, and the oil pump is supported by the pump housing alone.   The bearing of the drive balancer shaft closest to the torque input means is offset to the torque input means side of a bearing of the driven balancer shaft closest to the oil pump. The balancer device for an internal combustion engine according to claim 1 or 2. The pump housing is formed in the lower housing and has a lateral extension defining an oil passage of the oil pump inside;
4. The lower half portion of the bearing of the drive balancer shaft closest to the torque input means is formed above the laterally extending portion. 5. 2. A balancer device for an internal combustion engine according to 1.   The balancer housing is configured to expose the driven balancer shaft between the pump housing and the pump housing, and the pump housing has a bearing hole that pivotally supports the driven balancer shaft. The balancer device for an internal combustion engine according to any one of claims 1 to 4. The balancer weight of the driven balancer shaft is divided into two axially across a journal portion supported by the bearing, and a bearing wall between the balancer weights forms a thrust bearing of the driven balancer shaft,
The bearing of the driven balancer shaft is provided on a bearing wall between the balancer weights and a shaft end wall on the pump housing side;
The driven balancer shaft is composed of a weight shaft on both balancer weight sides and a pump shaft on the oil pump side, which are connected to each other by a joint provided between the balancer housing and the pump housing,
The balancer device for an internal combustion engine according to any one of claims 1 to 5, wherein the joint includes a key and a key groove extending in a direction orthogonal to the axial direction.

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