JP3875312B2 - Inline 4-cylinder engine balancer device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  In the present invention, a balancer gear is provided on a balancer weight rotatably supported on a balancer shaft, and the balancer gear is driven via a balancer drive gear provided on a crankshaft and an idle gear rotatably supported on an idle shaft.Inline 4 cylinderThe present invention relates to an engine balancer device.
[0002]
[Prior art]
  Such an engine balancer device is already known from Japanese Patent Application Laid-Open No. 4-277349.
[0003]
[Problems to be solved by the invention]
  By the way, the conventional balancer device supports the rear balancer shaft so as to be positioned rearward and upward of the crankshaft in a casing that supports the crankshaft and projects the cylinder forward and upward, and is positioned in front of the rear balancer. The idle shaft is supported. For this reason, the casing for housing the rear balancer shaft and the idle shaft is enlarged behind the cylinder, and it is difficult to secure a space for mounting auxiliary devices such as a starter motor behind the cylinder.
[0004]
  The present invention has been made in view of the above circumstances,Of inline 4-cylinder engineIt aims at arranging a balancer shaft compactly in a casing behind a cylinder.
[0005]
[Means for Solving the Problems]
  In order to achieve the above object, according to the first aspect of the present invention, a balancer drive gear provided on a crankshaft is meshed with an idle gear rotatably supported on an idle shaft, and the idle gear is rotated on the balancer shaft. Engage with a freely supported balancer gearInline 4 cylinderStand up in the engine balancerThe third cylinder among the first to fourth cylindersOn the upper wall of the rear casing, a raised portion of the box structure with the lower surface open and surrounded by the front wall, the rear wall and a pair of side walls is projected upward to correspond to a part of the longitudinal direction of the crankshaft And the front wall of the raised portionThe thirdA cylinder side wall forming the cylinder side wall, and the pair of side walls of the raised portionThe third journal part and the fourth journal part of the first to fifth journal partsAnd the balancer shaft supported by the extension of the journal support portion is disposed inside the raised portion.
[0006]
  According to a second aspect of the present invention, in addition to the configuration of the first aspect, an idle shaft is disposed below the balancer shaft.
[0007]
  According to a third aspect of the present invention, in addition to the configuration of the first aspect, the balancer shaft is fixed to an extension portion of the journal support portion via a fixing member.
[0008]
  According to a fourth aspect of the present invention, in addition to the configuration of the third aspect, the end portion of the balancer shaft protrudes from one extension portion of the journal support portion, and the phase of the balancer shaft is adjusted by the protruding portion. And the protruding portion is fixed to the one extension through a fixing member.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, embodiments of the present invention will be described based on examples of the present invention shown in the accompanying drawings. 1 to 8 show an embodiment of the present invention. FIG. 1 is an overall side view of an engine mounted on a motorcycle, FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. 1, and FIG. 4 is a sectional view taken along the line 4-4 of FIG. 3, FIG. 5 is a sectional view taken along the arrow 5 in FIG. 4, FIG. 6 is a sectional view taken along the line 6-6 in FIG. FIG. 8 is an explanatory view of the operation.
[0010]
  As shown in FIG. 1, an in-line four-cylinder engine E supported on a body frame 1 of a motorcycle by three bolts 2...₁Is disposed inclining upward in front of the vehicle body. The casing of the engine E includes an upper casing 4 constituting the upper half of the crankcase, the upper half of the transmission case and the cylinder block, and a lower casing 5 constituting the lower half of the crankcase and the lower half of the transmission case. And a cylinder head 6 coupled to the upper end of the cylinder block of the upper casing 4, a head cover 7 coupled to the upper end of the cylinder head 6, and an oil pan 8 coupled to the lower surface of the lower casing 5.
[0011]
  The engine E includes a secondary balancer device for reducing secondary vibration. The secondary balancer device includes a front balancer Bf and a rear balancer Br. The front balancer Bf includes a front balancer shaft 9 disposed below the crankshaft 3 and slightly forward of the vehicle body. The rear balancer Br is a crankshaft 3. A rear balancer shaft 10 disposed slightly above and rearward of the vehicle body, and an idle shaft 11 disposed below the rear balancer shaft 10. The front balancer shaft 9 and the rear balancer shaft 10 are disposed at substantially symmetrical positions with respect to the crankshaft 3. The transmission housed in the rear part of the upper casing 4 and the lower casing 5 includes a main shaft 12 located behind the crankshaft 3 and a countershaft 13 arranged behind the main shaft 12.
[0012]
  As shown in FIGS. 2 and 3, first to fourth cylinders 21 formed in the upper casing 4.₁~ 21_FourAnd the first to fourth pistons 22 respectively.₁~ 22_FourAre slidably fitted. The crankshaft 3 has first to fifth journal parts 23.₁~ 23_FiveAnd these first to fifth journal parts 23₁~ 23_FiveFirst to fourth pin portions 24 provided therebetween₁~ 24_FourWith. First to fifth journal parts 23₁~ 23_FiveAre the first to fifth journal support portions 25 formed in the upper casing 4.₁~ 25_FiveAnd the first to fifth journal support portions 26 formed in the lower casing 5.₁~ 26_FiveAnd the first to fourth pin portions 24 are supported rotatably.₁~ 24_FourAnd the first to fourth pistons 22₁~ 22_FourAnd the first to fourth connecting rod 27₁~ 27_FourConnected with.
[0013]
  First to fifth journal support portions 26 of the lower casing 5₁~ 26_FiveAnd the first to fifth journal support portions 25 of the upper casing 4₁~ 25_FiveAre integrally coupled by five front casing clamping bolts 14 arranged in front of the crankshaft 3 and five rear casing clamping bolts 15 arranged in the rear of the crankshaft 3. The rigidity is increased by the fastening force at that time.
[0014]
  That is, the lower casing 5 that supports the front balancer shaft 9 is made of a steel front casing clamping bolt 14 that has a higher longitudinal elastic modulus (Young's modulus) than the aluminum alloy that is the material of the lower casing 5, and the rear casing. Since the fastening bolts 15 are fastened, the rigidity of the front balancer support portion of the lower casing 5 is increased.
[0015]
  Each cylinder 21 has a cylinder head 6.₁~ 21_FourIs formed corresponding to the intake port 6 connected to the combustion chamber 28.₁, 6₁And exhaust port 6₂, 6₂Are provided with intake valves 29, 29 and exhaust valves 30, 30. The intake valves 29 and 29 and the exhaust valves 30 and 30 are driven by an intake camshaft 31 and an exhaust camshaft 32 supported on a coupling surface of the cylinder head 6 and a camshaft holder (not shown).
[0016]
  A timing chain that houses a drive sprocket 33 provided at the right end of the crankshaft 3 and a timing chain 34 that transmits the rotation of the drive sprocket 33 to the intake camshaft 31 and the exhaust camshaft 32 on the right end surface of the engine E. A chamber 35 is provided, and a part of the opening to the outside is covered with a timing chain chamber cover 36. An AC generator 37 is provided at the left end of the crankshaft 3, and the outer side thereof is covered with an AC generator cover 38.
[0017]
  As shown in FIGS. 3 to 5, the third journal portion 23 of the crankshaft 3._ThreeAnd the fourth journal part 23_FourThe third journal support portion 25 formed in the upper casing 4 to support the_ThreeAnd the fourth journal support section 25_FourIn the middle, the left and right ends of the idle shaft 11 of the rear balancer Br are constructed. The third journal support portion 25 extends from the rear surface of the cylinder block to the upper surface of the upper casing 4._ThreeAnd the fourth journal support section 25_FourIs extended outward from the outer wall of the upper casing 4 to provide a casing raised portion 41. The casing raised portion 41 includes a ceiling wall portion 41d covering the upper surface and the rear surface thereof, and the third cylinder 21 connected to the front of the ceiling wall portion 41d._ThreeCylinder side wall portion 41e constituting the side wall of the third journal support portion 25._ThreeThe fourth journal support part 25_FourThe ceiling wall portion 41d and the cylinder side wall portion 41e constitute a highly rigid box structure with only the lower surface opened. The third journal support portion 25 that constitutes the left and right side walls of the casing raised portion 41._ThreeAnd the fourth journal support section 25_FourThe left and right ends of the rear balancer shaft 10 of the rear balancer Br are installed.
[0018]
  The rear balancer shaft 10 includes a fourth journal support portion 25._FourA support hole 41b made of a through-hole formed in the third journal support portion 25 and the third journal support portion 25._ThreeThe fourth journal support portion 25 is inserted into the support hole 41a made of a blind hole formed from the side of the support hole 41b._FourIt is fixed by the fixing member 42 at the end portion protruding from the outside. As will be described later, the rear balancer shaft 10 is composed of an eccentric shaft, and the phase of the eccentric portion 10b can be adjusted by engaging and rotating a tool in a groove 10a formed on the right end thereof. . The fixing member 42 for fixing the rear balancer shaft 10 so that it cannot rotate and cannot move in the axial direction after the adjustment is completed is formed in a substantially J shape, and the bolt 43 After tightening with a bolt 44, the fourth journal support portion 25 of the casing raised portion 41 is secured with a bolt 44._FourFixed to.
[0019]
  The idle shaft 11 has a fourth journal support portion 25._FourA support hole 25b made of a through hole and a third journal support part 25_ThreeThe fourth journal support portion 25 is formed in the support hole 25a made of a through hole formed in_Four3rd journal support part 25 inserted from the side_ThreeIt is fixed by the fixing member 45 and the bolts 46 and 47 at the end portion that passes through. The right end of the idle shaft 11 is a fourth journal support portion 25 with a bolt 48._FourIt is positioned in the axial direction by a washer 49 fixed to. The idle shaft 11 is also composed of an eccentric shaft, and the phase of the eccentric part 11b can be adjusted by engaging and rotating a tool in a groove 11a formed at the right end before the idle shaft 11 is fixed.
[0020]
  Fourth journal portion 23 of the crankshaft 3_FourA balancer drive gear 51 is integrally formed on the outer periphery of the balancer unit 50 adjacent to the left side of the balancer. Ball bearings 53, 53 are axially positioned on the outer periphery of the eccentric portion 11 b of the idle shaft 11 via a collar 52, and an idle gear 55 is detachably supported by the ball bearings 53, 53 via a clip 54. Meshes with the balancer drive gear 51.
[0021]
  As is clear from FIG. 7, a rear balancer weight 58 is rotatably supported on the outer periphery of the eccentric portion 10 b of the rear balancer shaft 10 via a first needle bearing 56 and a second needle bearing 57. The rear balancer weight 58 includes a weight portion 58a and a cylindrical shaft portion 58b. A rear balancer gear 60 supported on the outer periphery of the cylindrical shaft portion 58b via a plurality of damper rubbers 59 ... meshes with the idle gear 55. To do. The left and right end portions of the rear balancer weight 58 and the third journal support portion 25 of the casing raised portion 41._ThreeAnd the fourth journal support section 25_FourBetween the first thrust washer 61 and the second thrust washer 62, respectively. The weight portion 58a of the rear balancer weight 58 is formed by the third connecting rod 27._ThreeIn order to avoid interference with the large end of the third journal support portion 25 of the casing raised portion 41._ThreeIs placed adjacent to.
[0022]
  Third journal support portion 25 of casing raised portion 41_ThreeThe first thrust washer 61 is provided with an annular cylindrical holding portion 61b extending toward the rear balancer weight 58 on the outer periphery of the main body portion 61a, and a third journal on the left side surface of the main body portion 61a. Support part 25_ThreeThrust washer support surface f₁The thrust force between the left end portion of the rear balancer weight 58 and the retainer 56a of the first needle bearing 56 is supported on the right side surface of the main body portion 61a, and the cylindrical holding portion 61b. Is engaged with the outer peripheral surface of the left end of the rear balancer weight 58, whereby the first thrust washer 61 itself is positioned in the radial direction with respect to the rear balancer weight 58.
[0023]
  On the other hand, the fourth journal support portion 25 of the casing raised portion 41._FourThe second thrust washer 62 is provided with an annular cylindrical holding portion 62b extending toward the rear balancer weight 58 on the inner periphery of the main body portion 62a. Journal support section 25_FourThrust washer support surface f₂And a thrust force between the right end of the rear balancer weight 58 and the right end of the rear balancer gear 60 on the left side of the main body 62a, and on the left end of the cylindrical holding portion 62b. The thrust force between the second needle bearing 57 and the retainer 57a is supported, and the outer peripheral surface of the cylindrical holding portion 62b is engaged with the inner peripheral surface of the right end of the rear balancer weight 58, whereby the second thrust washer 62 itself Is positioned with respect to the rear balancer weight 58 in the radial direction.
[0024]
  As is apparent from the comparison of the shapes of the first thrust washer 61 and the second thrust washer 62, the cylindrical holding portion 61b of the first thrust washer 61 is formed on the outer periphery of the main body portion 61a. The first needle bearing 56 can be moved toward the main body 61a without interfering with the main body 61a. As a result, the axial center line A of the first needle bearing 56 is brought close to the center line B passing through the center of gravity of the weight portion 58a of the rear balancer weight 58, and the offset amount α between the center lines A and B is minimized. Can be suppressed. As a result, the unbalanced load acting on the first needle bearing 56 is reduced, so that the first needle bearing 56 having a small capacity can be used, and the durability can be improved.
[0025]
  When the rear balancer weight 58 is assembled in the casing raised portion 41, the rear balancer weight 58, the rear balancer gear 60, the damper rubber 59, etc., the first needle bearing 56, the second needle bearing 57, the first thrust washer 61, and the second The sub-assembly of the thrust washer 62 is assembled together. In the state where the subassembly is assembled at the regular assembly position shown in FIG. 4, the first thrust washer 61 and the second thrust washer 62 are connected to the third journal support portion 25 of the casing raised portion 41._ThreeAnd the fourth journal support section 25_FourTo prevent it from falling off. However, while the sub-assembly is inserted from the opening of the upper casing 4 to the regular assembly position, as shown in FIG._ThreeAnd the fourth journal support section 25_FourDistance D between opposite faces₁Is a third journal support portion 25 in the regular assembly position for weight reduction._ThreeAnd 4th journal support section 25_FourDistance D between₂(F₁, F₂Since the first thrust washer 61 and the second thrust washer 62 are likely to fall off the rear balancer weight 58, there is a problem that workability is lowered. In particular, since the subassembly is assembled to the deepest part of the casing raised portion 41, the operator's hand is difficult to enter and the operation is difficult.
[0026]
  Therefore, in this embodiment, as shown in FIGS. 3, 4 and 6, the third journal support portion 25 is used._ThreeAnd the fourth journal support section 25_FourThe thrust washer support surface f from the opening of the upper casing 4 to the opposite surface of₁, F₂Thrust washer guide surface f_Three, F_FourIs projected. Left thrust washer support surface f₁And slide guide surface f_ThreeAre formed flush and the right thrust washer support surface f₂And thrust washer guide surface f_FourAre formed flush with each other, so that a pair of opposing thrust washer support surfaces f₁, F₂The distance between and a pair of opposing thrust guide surfaces f_Three, F_FourThe distance between them is D₂Is equal to
[0027]
  Thus, when the sub-assembly of the rear balancer weight 58 is inserted into the assembly position in the casing raised portion 41, a pair of thrust washer guide surfaces f starting from the opening of the upper casing 4 is obtained._Three, F_FourWhile the first thrust washer 61 and the second thrust washer 62 at both ends of the subassembly are in contact with each other, the subassembly is inserted into the assembly position in the casing raised portion 41 while sliding. Thus, the first thrust washer 61 and the second thrust washer 62 are not dropped from the rear balancer weight 58, and the left and right thrust washer support surfaces f₁, F₂As a result, the assembling workability is greatly improved.
[0028]
  As is apparent from FIGS. 3 to 6, an arc-shaped rib 63 protrudes from the bottom of the casing raised portion 41, and the fourth journal support portion 25 can be seen from the rib 63._FourA circular opening 41c that can be closed by a plug 64 (see FIG. 4) is formed. A part of the rear balancer gear 60 and the phase alignment mark 63a of the rib 63 are visible through the opening 41c, and the phase alignment mark engraved on one tooth by rotating the rear balancer gear 60 by inserting a finger from the opening 41c. By making the mark 60a (see FIG. 5) face the phase alignment mark 63a of the rib 63, the phase of the rear balancer gear 60 can be adjusted when the rear balancer Br described later is assembled.
[0029]
  Further, when the subassembly is inserted into the casing raised portion 41, the rear balancer gear 60 is abutted against the rib 63 and positioned roughly as shown in FIGS. It is prevented from falling off at the bottom of the portion 41, and the assembling work is facilitated.
[0030]
  As shown in FIGS. 3 and 4, the front balancer shaft 9 of the front balancer Bf is connected to the third journal support portion 26 of the lower casing 5._ThreeAnd the fourth journal support section 26_FourAnd a first balance bearing 67 having a first needle bearing 65, a second needle bearing 66, a weight portion 67a and a cylindrical shaft portion 67b, and a first thrust washer 68. The second thrust washer 69 and the front balancer gear 71 that meshes with the damper rubber 70 and the balancer drive gear 51 are supported. The front balancer shaft 9 is fixed to the lower casing 5 by a fixing member 72 and bolts 73 and 74.
[0031]
  As apparent from FIG. 4, the front balancer Bf has a structure symmetrical to the rear balancer Br with respect to the crankshaft 3 except that members corresponding to the idle shaft 11 and the idle gear 55 are not provided. The description of the overlapping structure is omitted. However, since the front balancer Bf is disposed at a relatively shallow position from the opening of the lower casing 5 and does not have a member corresponding to the idle gear 55, it can be easily assembled and phased. Br thrust washer guide surface f_Three, F_FourThe thing corresponding to these, or the thing equivalent to the rib 63 is unnecessary.
[0032]
  In FIG. 4, since the cylindrical holding portion 68b of the first thrust washer 68 of the front balancer Bf is formed on the outer periphery of the main body portion 68a, the first needle bearing 65 is moved to the main body portion without interfering with the cylindrical holding portion 68b. The center line of the first needle bearing 65 can be moved closer to the center line of the weight portion 67a of the front balancer weight 67. As a result, similarly to the above-described rear balancer Br, it is possible to reduce a load caused by an unbalanced load acting on the first needle bearing 65 of the front balancer Bf.
[0033]
  Thus, the number of teeth of the rear balancer gear 60 and the number of teeth of the front balancer gear 71 are both set to one half of the number of teeth of the balancer drive gear 51 provided on the crankshaft 3. The rear balancer gear 60 rotates in the same direction as the crankshaft 3 at twice the rotational speed of the crankshaft 3, and the front balancer gear 71 rotates in the opposite direction to the crankshaft 3 at twice the rotational speed of the crankshaft 3. Rotates and reduces secondary vibrations of engine E as is well known.
[0034]
  In FIG. 3, in order to effectively reduce the vibration of the engine E, it is desirable that the front balancer shaft 9 and the rear balancer shaft 10 are arranged symmetrically about the crankshaft 3. Cylinder axis L₁And the distance between the front balancer shaft 9 and d₁Cylinder axis L₁And the distance between the rear balancer shaft 10 and d₂Cylinder axis L of the front balancer shaft 9 and the rear balancer shaft 10₁The distance in the direction along_ThreeThen the distance d₁And distance d₂Are set equal and the distance d_ThreeConnecting rod 27₁~ 27_FourIt is desirable to set it to be approximately equal to the length of.
[0035]
  By arranging the front balancer shaft 9 at the front lower side of the crankshaft 3 and the rear balancer shaft 10 at the rear upper side of the crankshaft 3, the above condition can be satisfied relatively easily. Inclined cylinder 21₁~ 21_FourSince the rear balancer shaft 10 is used as a space for arranging various auxiliary devices (for example, the air cleaner 16 and the fuel tank 17 shown in FIG. 1), the rear balancer shaft 10 may interfere with the auxiliary devices. However, in this embodiment, the minimum casing raised portion 41 is provided on the upper surface of the upper casing 4 and the rear balancer shaft 10 is accommodated therein.₁~ 21_FourIt is possible to avoid the interference with auxiliary devices by maximizing the space behind. In addition, the idle shaft 11 is disposed not behind the rear balancer shaft 10 but behind the cylinder 21.₁~ 21_FourIt is possible to secure a larger space behind the rear.
[0036]
  As is apparent from FIG. 4, the third journal portion 23 of the crankshaft 3_ThreeAnd the fourth journal part 23_FourThe third journal support portion 25 of the upper casing 4 for supporting_ThreeAnd the fourth journal support section 25_FourThe rear balancer shaft 10 is supported by the third journal portion 23._ThreeAnd the fourth journal part 23_Four3rd journal support part 26 of the lower casing 5 which supports_ThreeAnd the fourth journal support section 26_FourThe front balancer shaft 9 is supported on the front. If the balancer shafts 9 and 10 are supported on the outer walls of the casings 4 and 5, the casings 4 and 5 need to be reinforced to counteract the centrifugal force acting on the balancer shafts 9 and 10 and the weight increases. As in this embodiment, the journal support portion 25 having high rigidity to support the crankshaft 3 is used._Three, 25_Four, 26_Three, 26_FourIf the balancer shafts 9 and 10 are supported using the above, reinforcement of the casings 4 and 5 becomes unnecessary and the weight is reduced. In particular, the journal support 25 of the upper casing 4₁~ 25_FiveAnd journal support 26 of the lower casing 5₁~ 26_FiveThe coupling rigidity is increased by the fastening force of the steel front fastening bolts 14 and the rear fastening bolts 15 having a higher longitudinal elastic modulus (Young's modulus) than the aluminum alloy that is the material of the upper casing 4. Therefore, the support rigidity of the front balancer shaft 9 and the rear balancer shaft 10 supported thereby is also improved. Thereby, the vibration generating force of the front balancer shaft 9 and the rear balancer shaft 10 (vibration suppression force for suppressing the vibration of the crankshaft 9) acts effectively, and the vibration of the entire engine E can be minimized. In particular, the rear balancer shaft 10 is supported by a casing raised portion 41 having a box structure in which only the lower surface is opened, and the rear balancer support portion is located in the vicinity of the fastening portion of the rear fastening bolts 15. Can be ensured. Next, the assembly of the rear balancer Br and the front balancer Bf having the above-described structure and the removal of the backlash will be described.
[0037]
  The rear balancer Br is assembled in a state where the upper casing 4 is fixed with its opening facing upward, the rear balancer weight 58, the rear balancer gear 60, the damper rubber 59,..., The first needle bearing 56, the second needle bearing 57, The subassembly in which the first thrust washer 61 and the second thrust washer 62 are temporarily assembled is moved from the opening of the upper casing 4 to the first washer 61 and the second thrust washer 62 through the thrust washer guide surface f as described above._Three, F_FourIt is inserted into the casing raised portion 41 while being guided by the guide. Subsequently, the tip of the rear balancer shaft 10 is connected to the fourth journal support portion 25 of the casing raised portion 41._FourThe third journal support portion 25 is inserted through the support hole 41b and penetrates through the inside of the subassembly._ThreeTo the support hole 41a.
[0038]
  Next, an idle gear 55 having ball bearings 53 and 53 preliminarily assembled on its inner periphery is inserted from the opening of the upper casing 4 and meshed with the rear balancer gear 60, and in this state, the tip of the idle shaft 11 is connected to the upper casing 4. Fourth journal support section 25_FourThe ball bearings 53 and 53 and the collar 52 are inserted through the support hole 25b. At this time, the idle gear 55 is retracted to a position indicated by a chain line in FIG. When the idle gear 55 is in the retracted position, the meshing relationship between the idle gear 55 and the rear balancer gear 60 is maintained.
[0039]
  Next, a finger is inserted through the opening 41 c of the casing raised portion 41 to rotate the rear balancer gear 60, so that the phase alignment mark 60 a faces the phase alignment mark 63 a of the rib 63. In this state, the journal support portion 25 of the upper casing 4₁~ 25_FiveThe journal 23 of the crankshaft 3₁~ 23_FiveHowever, since the idle gear 55 is retracted to the chain line position as described above, the balancer drive gear 51 of the crankshaft 3 does not mesh with the idle gear 55. Subsequently, the crankshaft 3 is rotated, for example, the first pin portion 24.₁And the fourth pin portion 24_FourIs positioned at the top dead center position. From this state, the idle gear 55 is slid to the solid line position in FIG. 4 and meshed with the balancer drive gear 51, and then the idle shaft 11 is locked to the support hole 25a.
[0040]
  Through the above procedure, the rear balancer gear 60 can be assembled so that the rear balancer gear 60 has a predetermined phase with respect to the phase of the crankshaft 3.
[0041]
  The front balancer Bf is assembled by assembling the front balancer shaft 9 and the front balancer weight 67 to the lower casing 5 and temporarily fixing the front balancer gear 71 so as to have a predetermined phase, so that the crankshaft 3 has a predetermined phase. The lower casing 5 may be coupled to the upper casing 4 temporarily fixed as described above. The assembly of the front balancer Bf can be easily performed because the front balancer Bf is disposed at a shallow position from the opening of the lower casing 5.
[0042]
  The backlash adjustment of the rear balancer Br is performed by adjusting the rotational positions of the rear balancer shaft 10 and the idle shaft 11 made of an eccentric shaft. As shown in FIG. 8 (A), the third journal support portion 25 of the casing raised portion 41._ThreeAnd the fourth journal support section 25_FourThe axis P 'of the eccentric portion 10b that supports the first needle bearing 56 and the second needle bearing 57 is eccentric by a distance β with respect to the axis P of both ends of the rear balancer shaft 10 supported by the upper balance. 4th third journal section 25_ThreeAnd the fourth journal part 25_FourThe axis Q ′ of the eccentric portion 11b that supports the idle gear 55 is eccentric by a distance γ with respect to the axis Q of both ends of the idle shaft 11 supported by the shaft. When the axis O of the crankshaft 3 is assumed, the angle θ formed by the line segment QO and the line segment QP is set to approximately 90 °.
[0043]
  First, as shown in FIG. 8 (A), the eccentric portion 10b (shaded portion) of the rear balancer shaft 10 is eccentrically fixed to an arrow a substantially parallel to the direction of the line segment QP and temporarily fixed. 11 eccentric portions 11b (shaded portions) are eccentrically fixed in an arrow b direction substantially parallel to the direction of the line segment OQ and temporarily fixed. At this time, the meshing between the rear balancer gear 60 and the idle gear 55 is loose, and the meshing between the idle gear 55 and the balancer drive gear 51 is also loose.
[0044]
  From this state, when the idle shaft 11 is rotated and fixed in the direction c of FIG. 8A by a predetermined angle (for example, about 120 °), the axis Q ′ of the eccentric portion 11 b of the idle shaft 11 approaches the crankshaft 3. 8B, the backlash between the balancer drive gear 51 and the idle gear 55 is adjusted to an appropriate size. At this time, although the distance between the idle gear 55 and the rear balancer gear 60 is slightly reduced, the meshing between the idle gear 55 and the rear balancer gear 60 is maintained in a loose state. Can be moved smoothly.
[0045]
  When the backlash between the balancer drive gear 51 and the idle gear 55 is adjusted as described above, the rear balancer shaft 10 is subsequently rotated by a predetermined angle (for example, about 90 °) in the direction of the arrow d in FIG. And fix. As a result, the rear balancer gear 60 moves in the direction of arrow f in FIG. 8B, and the backlash between the rear balancer gear 60 and the idle gear 55 is adjusted to an appropriate size. At this time, since the distance between the idle gear 55 and the rear balancer gear 60 is slightly reduced in the previous process, the amount of movement of the rear balancer gear 60 in the direction of the arrow f can be reduced accordingly. Of course, the backlash between the already adjusted balancer drive gear 51 and the idle gear 55 is not affected by the movement of the rear balancer gear 60 in the direction of the arrow f.
[0046]
  Adjustment of the backlash of the front balancer Bf can be easily performed only by rotating the front balancer shaft 9 provided with the eccentric portion 9b. That is, the third journal portion 26 of the lower casing 5_ThreeAnd the fourth journal part 26_FourSince the axis of the eccentric portion 9b supporting the front balancer gear 71 is eccentric by a predetermined distance with respect to the axis of both ends of the front balancer shaft 9 supported by the front balancer shaft 9, when the front balancer shaft 9 is rotated, the front balancer gear The backlash is adjusted as 71 approaches / separates from the balancer drive gear 51 of the crankshaft 3.
[0047]
  As mentioned above, although the Example of this invention was explained in full detail, this invention can perform a various design change in the range which does not deviate from the summary.
[0048]
  For example, in the embodiment, the secondary balancer device is illustrated, but the present invention can also be applied to the primary balancer device.
[0049]
【The invention's effect】
  As described above, according to the first aspect of the present invention, the raised portion projects upward from the upper wall of the casing behind the standing cylinder so as to correspond to a part of the longitudinal direction of the crankshaft. Since the balancer shaft is disposed inside the raised portion, the balancer shaft can be disposed at an appropriate position by effectively utilizing the dead space behind the cylinder without increasing the size of the casing. In addition, the raised portion has a box structure that is surrounded by a front wall, a rear wall, and a pair of side walls and has an open lower surface.ThirdIt is composed of a highly rigid cylinder sidewall that forms the cylinder sidewall, and the pair of sidewalls of the raised portion are highly rigid.3rd, 4th of 1st-5th journal support partSince it is constituted by the extension portion of the journal support portion, the balancer shaft can be reliably supported by further increasing the rigidity of the raised portion.
[0050]
  According to the second aspect of the present invention, since the idle shaft is arranged behind the balancer shaft, a space for arranging auxiliary devices behind the cylinder can be secured.
[Brief description of the drawings]
[Fig. 1] Overall side view of an engine mounted on a motorcycle
2 is a sectional view taken along line 2-2 in FIG.
3 is a cross-sectional view taken along line 3-3 in FIG.
4 is a cross-sectional view taken along line 4-4 of FIG.
5 is a view taken in the direction of arrow 5 in FIG.
6 is a sectional view taken along line 6-6 in FIG.
7 is an enlarged view of the main part of FIG.
FIG. 8 is an explanatory diagram of the action.
[Explanation of symbols]
3 Crankshaft
4 Upper casing (casing)
10 Rear balancer shaft (balancer shaft)
11 Idle shaft
23_Three, 23_Four        Journal department
24 ₁       1st cylinder
24 ₂       2nd cylinder
24 _Three       3rd cylinder
24 _Four       4th cylinder
25 ₁       1st journal support
25 ₂       Second journal support
25 _Three       Third journal support
25 _Four       Fourth journal support
25 _Five       5th journal support
41 Casing raised part (raised part)
41e Cylinder side wall
42 Fixing member
51 Balancer drive gear
55 Idle Gear
60 Balancer gear

Claims (4)

A balancer drive gear (51) provided on the crankshaft (3) is meshed with an idle gear (55) rotatably supported on the idle shaft (11), and the idle gear (55) is rotated on the balancer shaft (10). In an in- line four-cylinder engine balancer device meshed with a freely supported balancer gear (60),
A part of the crankshaft (3) in the longitudinal direction is placed on the upper wall of the casing (4) behind the third cylinder (21 ₃ ) of the first cylinder (21 ₁ ) to the fourth cylinder (21 ₄ ) standing upright . so as to correspond to the front wall, surrounded by a rear wall and a pair of side walls upwardly projecting ridge of the box structure lower surface is opened (41) to said front wall of said raised portion (41) first The cylinder side wall portion (41e) that forms the side wall of the three cylinders (21 ₃ ) is used, and the pair of side walls of the raised portion (41) are connected to the first journal portion (23 ₁ ) to fifth portion of the crankshaft (3) . Of the journal portion (23 ₅ ), the journal portion is constituted by an extension portion of a pair of journal support portions (25 ₃ , 25 ₄ ) that supports the third journal portion (23 ₃ ) and the fourth journal portion (23 ₄ ). support (25 _3, 5 ₄₎ balancer apparatus of an in-line four-cylinder engine, characterized in that arranged in the interior of the balancer shaft which supports the extension part (the raised portion 10) (41) of. The balancer device for an in- line four-cylinder engine according to claim 1, characterized in that an idle shaft (11) is arranged below the balancer shaft (10). The balancer for an in- line four-cylinder engine according to claim 1, wherein the balancer shaft (10) is fixed to an extension of the journal support portion (25 ₃ , 25 ₄ ) via a fixing member (42). apparatus. An adjustment portion for projecting an end portion of the balancer shaft (10) from one extension portion of the journal support portion (25 ₃ , 25 ₄ ), and adjusting the phase of the balancer shaft (10). The balancer device for an in- line four-cylinder engine according to claim 3, wherein the protruding portion is fixed to the one extension portion via a fixing member (42).

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