JP2007078080A - Engine balancer equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED To compactly arrange an intermediate gear for transmitting the rotational power of a crankshaft to a balancer.
A balancer device for an engine 10 including a balancer 52 that rotates with the rotational power of a crankshaft 33 includes a starter motor 68 that transmits starting power to the crankshaft 33 to rotate the crankshaft 33. A starter freewheel gear 61 for transmitting power from the output shaft 69 to the crankshaft 33 is provided between the crankshaft 33 and the output shaft 69 of the starter motor 68, and between the crankshaft 33 and the balancer 52. The balancer driving gear 61 for transmitting power from the crankshaft 33 to the balancer 52 is provided, and the starter freewheel gear 61 and the balancer driving gear 61 are arranged on the same axis O3. Preferably, the starter freewheel gear 61 is used as a balancer driving gear.
[Selection] Figure 2

Description

  The present invention relates to an engine balancer device.

  Patent Document 1 below discloses a technology related to a two-shaft secondary balancer device for an engine having two front and rear balancers.

  In such a biaxial secondary balancer device, it is necessary to rotate the two balancers in directions opposite to each other. Therefore, the rotational power of the crankshaft can be directly transmitted to one of the balancers via the crank gear. However, the other balancer must transmit power by interposing an idler gear or the like with the crank gear.

Therefore, in Patent Document 1, a clutch gear is arranged behind the crank gear and meshed with the crank gear, and a front balancer is meshed with the crank gear and a rear balancer is meshed with the clutch gear. Yes.
Japanese Examined Patent Publication No. 2-52134

  Since the technique of Patent Document 1 uses a clutch gear to transmit power to the rear balancer, there is no need to provide an idle gear dedicated to the balancer, and the number of parts can be reduced and the crankcase can be made compact. is there.

  However, since the clutch gear is connected to the transmission, the degree of freedom in the arrangement of the crankcase is small, and the arrangement of the rear balancer is greatly limited. Since it is important for the balancer device to appropriately set the relative arrangement of the two balancers in order to reduce vibration, when the arrangement of one balancer is restricted, the arrangement of the other balancer is also restricted, The design including the connection with peripheral parts became difficult, and there was a limit to the compactness of the crankcase.

  On the other hand, the balancer is provided with a weight that is eccentric with respect to the rotational axis, and the weight and the crankshaft need to be appropriately set in phase in the rotational direction. The phase alignment between the crankshaft and the balancer is normally performed by providing stamps such as punch marks on the side surfaces of both gears and aligning the marks.

  However, in the case of a multi-cylinder engine, a plurality of webs are usually provided on the crankshaft. Due to the layout in the crankcase, a crank gear that transmits power to the balancer is placed between the web and the web. There are cases where it is unavoidable. In this case, since the web is arranged close to the side of the crank gear, it is difficult to stamp the crank gear with a punch or the like.

  In addition, in order to match the phase with the crankshaft, the two front and rear balancers need to be engraved on each. However, since the same components are usually used for the two balancers, Two marks for later use will be added. However, if both markings are of the same type (for example, punch marks), it is difficult to determine which marking should be used to set the phase.

  The present invention has been made in view of the above circumstances, and has as its first object to compactly arrange a balancer driving gear for transmitting the rotational power of the crankshaft to the balancer.

  The second object of the present invention is to make it easy to form a mark on the transmission gear that transmits power to the balancer, and to easily distinguish the two marks formed on the balancer. The purpose of 3.

  The invention according to claim 1 is a balancer device for an engine having a balancer that is rotated by the rotational power of the crankshaft, comprising a starter motor that transmits starting power to the crankshaft to rotate the crankshaft, A starter freewheel gear for transmitting power from the output shaft to the crankshaft is provided between the crankshaft and the output shaft of the starter motor, and the crankshaft is interposed between the crankshaft and the balancer. The balancer driving gear for transmitting power to the balancer is provided, and the starter free wheel gear and the balancer driving gear are arranged on the same axis.

  According to this, compared with the case where the starter freewheel gear and the balancer driving gear are arranged on different axes, they can be arranged more compactly as viewed from the side.

  According to a second aspect of the present invention, in the first aspect of the invention, the starter freewheel gear is also used as the balancer driving gear.

  According to this, it is possible to reduce the number of parts by sharing the parts, and by using the starter motor freewheel gear of the starter motor having a high degree of freedom of arrangement as compared with the clutch gear or the like as the balancer driving gear, The balancer layout can be easily designed, and a compact layout is also possible. Also, the starter freewheel gear that is used only at the time of starting can be effectively utilized as a balancer driving gear.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the starter freewheel gear and the balancer drive gear shaft center, the balancer shaft center, and the starter motor output shaft center, Are arranged in a triangular shape.

  By adopting such a configuration, the starter motor, the starter freewheel gear and the balancer driving gear, and the balancer can be arranged in a compact manner.

  The invention according to claim 4 is the invention according to claim 3, wherein a line segment connecting an axis of the starter freewheel gear and the balancer driving gear and an output axis of the starter motor, and the starter motor An intersection angle between a free wheel gear and the axis of the balancer driving gear and a line segment connecting the axis of the balancer is an acute angle.

  By adopting such a configuration, the starter motor, the starter freewheel gear and the balancer driving gear, and the balancer can be arranged more compactly.

  The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein a cylinder is disposed above the crankshaft, a transmission is disposed behind, and the transmission is disposed behind the cylinder. The starter freewheel gear and the balancer driving gear are arranged above the transmission, and one of the starter motor and the balancer is placed behind the starter freewheel gear and the balancer driving gear and above the transmission. The other is arranged behind the cylinder above the starter freewheel gear and the balancer driving gear.

  According to this, a starter motor, a starter freewheel gear, and a balancer drive, in a space slightly behind a drive system power transmission component (crankshaft, transmission, clutch, etc.) behind the cylinder and above the transmission. The gear and the balancer can be arranged in a compact manner, and the balancer and the starter motor can be easily assembled.

  The invention according to claim 6 is the invention according to any one of claims 1 to 5, comprising the balancer and another balancer that is rotated by the rotational power of the crankshaft, wherein the other balancer is the crank. Power is transmitted from a shaft through a conduction gear, and a mark is formed on the conduction gear to set a phase in a rotational direction with respect to the other balancer. The conduction gear is molded, and the mark is The conductive gear is molded simultaneously with the molding of the conductive gear.

  According to this, even when the conductive gear is arranged at a place where it is difficult to form a mark by machining such as a punch mark, the mark can be easily provided.

  The invention according to claim 7 is the invention according to any one of claims 1 to 6, comprising the balancer and another balancer that is rotated by the rotational power of the crankshaft, wherein both of the balancers are the same component. The two balancers are provided with two marks for each balancer for setting the phase in the rotation direction, and the two marks have different forms.

  According to this, the mark used for the phase alignment of each balancer can be easily determined.

  According to an eighth aspect of the present invention, in an engine including a balancer that is rotated by the rotational power of the crankshaft, a transmission gear that transmits the rotational power of the crankshaft to the balancer is provided, and the transmission gear is rotated with respect to the balancer. A mark for setting a phase of the direction is formed, the conductive gear is molded, and the mark is molded simultaneously with the molding of the conductive gear.

  According to this, even when the conductive gear is arranged at a place where it is difficult to form a mark by machining such as a punch mark, the mark can be easily provided.

  According to a ninth aspect of the present invention, in the balancer device for an engine provided with two balancers rotating by the rotational power of the crankshaft, both the balancers are composed of the same parts, and both the balancers have a rotational direction. Two marks for each balancer for setting the phase are provided, and the two marks have different forms.

  According to this, the mark used for the phase alignment of each balancer can be easily determined.

  The invention according to claim 10 is the invention according to claim 9, further comprising a transmission gear for transmitting the rotational power from the crankshaft to the balancer, and setting the phase of the rotation direction with respect to the balancer in the transmission gear. The conductive gear is molded and the mark is molded simultaneously with the formation of the conductive gear.

  According to this, even when the conductive gear is arranged at a place where it is difficult to form a mark by machining such as a punch mark, the mark can be easily provided.

  The invention described in claim 11 is the invention described in claim 6, 8, or 10, characterized in that the transmission gear is molded integrally with a crankshaft.

  According to this, the mark of the conduction gear can be integrally molded together with the crankshaft.

  FIG. 1 is a left side view of an engine according to an embodiment of the present invention. The engine 10 is mainly used for a motorcycle, and includes a crankcase 11, a cylinder head 12 provided at an upper portion of the crankcase 11, and an oil pan 13 provided at a lower portion of the crankcase 11. ing.

  A cylinder 14, a crank chamber 15, a mission chamber 16, a breather chamber 17, and a balancer chamber 18 are formed in the crankcase 11. The crankcase 11 includes a cylinder 14, an upper portion of the crank chamber 15, an upper portion of the transmission chamber 16, an upper case 21 constituting the breather chamber 17, and a lower case 22 constituting the lower portion of the crank chamber 15 and the lower portion of the transmission chamber 16. The upper case 21 and the lower case 22 are joined by a bolt or the like at the mating surface 23.

  The mating surface 23 is disposed in a slightly downward inclined manner with respect to the horizontal line, and the axis O7 of the cylinder 14 is disposed in a slightly forward inclined manner with respect to the vertical line. The breather chamber 17 and the balancer chamber 18 are arranged side by side behind the cylinder 14 and above the mission chamber 16, and are closed at the top by a common lid 78. A starter motor 68 is disposed behind the breather chamber 17.

  The engine 10 is a parallel multi-cylinder engine (for example, a parallel 4-cylinder engine) having a plurality of cylinders arranged in a direction substantially perpendicular to the traveling direction. The exhaust pipe 25 is connected. The exhaust pipe 25 extends downward through the front side of the engine 10, bends rearward, passes through the lower side of the engine 10, and extends further rearward. One end of a cooling water supply hose 26 is connected to the front portion (exhaust side) of the cylinder 14, and the other end of the supply hose 26 is discharged from a water pump 27 provided on the left side of the engine 10. It is connected to the outlet 27A. The rear end of the suction hose 28 is connected to the suction port 27 </ b> B of the water pump 27, and the front end of the suction hose 28 is connected to the tank 30 of the radiator 29. A throttle body 31 is connected to the intake port of each cylinder at the rear of the cylinder head 12, and the air-fuel mixture is supplied to the engine 10 via the throttle body 31. A generator 32 is provided on the left side of the engine 10 on the front side of the water pump, and the rotor of the generator 32 is connected to the end of the crankshaft 33.

  FIG. 2 is a right side view schematically showing a power transmission system in the engine 10. The crankshaft 33 is disposed in the crank chamber 15 with the axis O1 in the left-right direction. The crankshaft 34 of the crankshaft 33 is connected to the large end portion of the connecting rod 35 and is connected to the small end portion of the connecting rod 35. The piston 36 is connected. The piston 36 is slidably fitted to the cylinder 14.

  A transmission device 37 is disposed in the transmission chamber 16 behind the crank chamber 15, and the transmission device 37 includes an input shaft 38 and an output shaft 39 substantially parallel to the crankshaft 33, as well as an input shaft 38 and an output. A transmission gear group 40 that transmits power to and from the shaft 39 is provided. A clutch gear 41 is provided at the end of the input shaft 38, and the clutch gear 41 meshes with a crank gear 45 b provided on the crankshaft 33. The output shaft 39 outputs traveling system power via a chain transmission mechanism (not shown).

  3 is a cross-sectional view taken along arrow III-III in FIG. The crankshaft 33 includes a plurality of webs 45a to 45d arranged in the axial direction, and journal portions 46a to 46c and crank pins 47a and 47b provided between both ends and each of the webs 45a to 45d. The journal portions 46a to 46c and the crank pins 47a and 47b are integrally molded by forging. Since the engine 10 of this embodiment is a parallel 4-cylinder, the crankshaft 33 is provided with eight webs, and the second and third (seventh and sixth from the left) webs 45b and 45c are arranged on the outer periphery. A crank gear having gear teeth is formed. The clutch gear 41 is engaged with the second crank gear 45b from the right.

[Configuration of starter device]
4 is a cross-sectional view taken along the line IV-IV in FIG. A starter freewheel gear 61 is engaged with the third crank gear (conduction gear) 45c from the right of the crankshaft 33. The starter freewheel gear 61 is rotatably supported by a support shaft 62 supported by the crankcase 11 via a bearing 63, and further, a first intermediate gear 64 is rotatably supported by the support shaft 62. The starter freewheel gear 61 is connected to the first intermediate gear 64 via a one-way clutch 65. Therefore, the starter freewheel gear 61 rotates integrally with the first intermediate gear 64 in one direction and relatively rotates in the other direction.

  The first intermediate gear 64 meshes with the second intermediate gear 66. The second intermediate gear 66 is rotatably supported by the support shaft 71, and the third intermediate gear 67 is supported by the support shaft 71 so as to be rotatable together with the second intermediate gear 66. The third intermediate gear 67 meshes with an output gear 70 provided on the output shaft 69 of the starter motor 68. Therefore, by the operation of the starter motor 68, the starting power is transmitted to the crankshaft 33 through the third intermediate gear 67, the second intermediate gear 66, the first intermediate gear 64, the starter freewheel gear 61, and the crank gear 45c. It is like that.

[Configuration of balancer device]
As shown in FIG. 2, a biaxial secondary balancer device is provided in the crankcase 11. The biaxial secondary balancer device includes two front and rear balancers 51, 52. The front balancer 51 is disposed in front of the crankshaft 33 and substantially parallel to the crankshaft 33, and the rear balancer 52 is The crankshaft 33 is disposed obliquely above the rear of the cylinder 14 and substantially parallel to the crankshaft 33. The balancer shaft 55 of the front balancer 51, the crankshaft 33, and the output shaft 39 of the transmission 37 are disposed on the mating surface 23 of the upper case 21 and the lower case 22 of the crankcase 11. The rear balancer 52 is disposed in the balancer chamber 18.

  As shown in FIG. 3, the front and rear balancers 51 and 52 are constituted by the same parts, and are supported by the balancer shaft 55 so as to be rotatable via a bearing 56 and a balancer shaft 55 supported by the crankcase 11. The balancer weight 57 and a balancer gear 59 connected to the balancer weight 57 via a damper 58 are provided. The balancer gear 59 of the front balancer 51 meshes with the crank gear 45 c so that rotational power is directly transmitted from the crankshaft 33.

  The starter freewheel gear 61 meshes with the balancer gear 59 of the rear balancer 52, and the starter freewheel gear 61 meshes with the crank gear 45c. Therefore, the rear balancer 52 is adapted to transmit rotational power from the crankshaft 33 via the starter freewheel gear 61.

  That is, the starter freewheel gear 61 has not only a function of transmitting the starting power from the starter motor 68 to the crankshaft 33 as shown in FIG. 4, but also the power to the rear balancer 52 as shown in FIG. It also functions as a “balancer drive gear” for transmitting the power.

  In FIG. 2, the starter motor 68 is disposed above the transmission 37 (the transmission chamber 16) behind the crankshaft 33 and the cylinder 14. The output shaft 69 and the axis O6 of the starter motor 68, the axis O3 of the starter freewheel gear (balancer driving gear) 61 and the first intermediate gear 64, and the axes of the second and third intermediate gears 66 and 67 O5 is arranged on a substantially straight line when viewed from the side. The axis O6 of the output shaft 69 of the starter motor 68, the axis O3 of the starter freewheel gear (balancer driving gear) 61 and the first intermediate gear 64, and the axis O4 of the rear balancer 52 are as follows. These are arranged in a triangular shape when viewed from the side, and these are housed in a space above the mission chamber 16 behind the cylinder 14.

  As shown in FIG. 4, the starter motor 68 has an output shaft 69 (output gear 70) inserted into the crankcase 11 and a motor body 68 </ b> A attached to the outer surface of the crankcase 11.

  FIG. 5 is a side view of the crank gear 45 c and the balancer gear 59 of the front balancer 51. A mark 74 for adjusting the phase with the balancer 51 is formed on the outer periphery of the crank gear 45c. As shown in FIGS. 3 and 4, the mark 74 is formed by notching (denting) the vicinity of the teeth of the crank gear 45 c, and is simultaneously molded when the crankshaft 33 is forged. It has become so. In the case of the present embodiment, the crankshaft 33 is formed by two split molds, and a position Y indicated by a one-dot chain line in FIG. 5 is a split face of the split mold. The mark 74 is formed by providing a projection on one split mold, and is provided at the outer end portion of the crank gear 45c in the mold releasing direction X.

  A mark 75 corresponding to the mark 74 provided on the crank gear 45c is provided on the side surface of the balancer gear 59, and the mark 75 of the present embodiment is a dot-like mark made of a punch mark. In order to incorporate the front balancer 51 into the crankcase 11, the gears 45 c and 59 are meshed with the mark 74 of the balancer gear 59 aligned with the mark 74 of the crank gear 45 c.

  Further, on the side surface of the balancer gear 59, in addition to the mark 75 by the punch mark, a linear mark 76 made of a cut line is formed. The cut line 76 serves as a mark when the rear balancer 52 is assembled into the crankcase 11. Specifically, as shown in FIG. 6, the rear balancer 52 is disposed so as to slightly protrude from the opening 77 of the balancer chamber 18 formed at the rear upper part of the crankcase 11, and a lid 78 attached to the opening 77. It comes to be covered with. The balancer 52 is incorporated into the crankcase 11 with the cut line 76 along the joint surface 79 between the opening 77 and the lid 78.

[Effects of this embodiment]
With the above configuration, this embodiment has the following operational effects.
(1) As shown in FIGS. 3 and 4, as a balancer driving gear for transmitting power from the crankshaft 33 to the rear balancer 52, a starter free gear for transmitting starter power from the starter motor 68 to the crankshaft 33 Since the wheel gear 61 is used, the number of parts can be reduced and the crankcase can be made more compact than when separate gears are used. In particular, since the balancer driving gear and the starter freewheel gear are arranged on one axis O3, the balancer driving gear and the starter freewheel gear can be configured compactly when viewed from the side.

  In addition, by using the starter free wheel gear 61 of the starter motor 68 having a higher degree of freedom of arrangement than the clutch gear 41 and the like for the balancer 52 on the rear side, the arrangement design of the balancer 52 can be easily performed. A compact arrangement is also possible. Further, the starter free wheel gear 61 of the starter motor 68 that is used only at the time of starting can be effectively used as a balancer driving gear.

  (2) As shown in FIG. 2, the output axis O6 of the starter motor 68, the axis O4 of the rear balancer 52, and the axis O3 of the starter freewheel gear (balancer drive gear) 61 are A line segment Z1 connecting the axis O3 of the starter freewheel gear (balancer driving gear) 61 and the output axis O6 of the starter motor 68, and a starter freewheel gear (for balancer driving). Since the line segment Z2 connecting the shaft center O3 of the gear 61 and the shaft center O4 of the rear balancer 52 is disposed at an acute angle, the starter motor 68, the rear balancer 52, the starter freewheel gear ( The balancer driving gear 61 can be arranged compactly.

  (3) As shown in FIG. 2, a starter motor 68, a rear balancer 52, and a starter freewheel gear (balancer drive gear) 61 are formed in a triangular shape in a space behind the cylinder 14 and above the transmission 37. Since these are disposed, they can be compactly disposed at a position slightly away from the transmission components (crankshaft 33, transmission 37, etc.) of the drive system power (travel system power). Attaching can also be performed easily.

  (4) As shown in FIGS. 3 and 5, the mark 74 provided on the crank gear 45c is molded simultaneously with the crankshaft 33 (crank gear 45c). Therefore, the mark 74 can be easily provided. In particular, as in the present embodiment, when the crank gear 45c is arranged in parallel with another crank gear 45b having substantially the same diameter, it is difficult to machine a punch or the like on the side surface of the crank gear 45c. It is more effective to form the mark 74 by molding.

  (5) The balancers 51 and 52 are composed of the same parts for the front and the rear, and the balancer gear 59 is set with a phase in the rotational direction with respect to the crankshaft 33 as shown in FIGS. For this purpose, two marks 75 and 76 for the front and rear are formed. Since the two marks 75 and 76 have different forms of the punch mark 75 and the cut line 76, which mark 75 and 76 should be used when the balancers 51 and 52 are used for front or rear use. Can be easily identified.

[Other Embodiments]
(1) The two marks 75 and 76 formed on the balancer gear 59 are not limited to punch marks and cut lines, but may be in other forms (for example, marks such as Δ and □).
(2) The mark 74 formed on the crank gear 45c is not limited to a recess, but may be a protrusion. In this case, a dent may be formed in the split mold for molding the crank gear 45c. Moreover, it is preferable to form a dent in the vicinity of the split surface Y from a viewpoint of die cutting.
(3) The gear forming the mark 74 is not limited to the crank gear 45c formed integrally with the crankshaft 33, and may be another power transmission transmission gear.
(4) The crankshaft 33 can be formed by casting as well as by forging.
(5) The starter motor 68 can be disposed above the starter free wheel gear (balancer driving gear) 61, and the rear balancer 52 is located behind the starter free wheel gear (balancer driving gear) 61. Can be arranged.
(6) The balancer driving gear and the starter freewheel gear can be configured as separate gears and arranged on the same axis.

  INDUSTRIAL APPLICABILITY The present invention can be suitably used for various engines such as for vehicles such as motorcycles and automobiles.

It is a left view of the engine concerning the embodiment of the present invention. It is a right view which shows roughly the power transmission system in an engine. FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2. FIG. 4 is a cross-sectional view taken along arrow IV-IV in FIG. 2. It is a side view of a crank gear and a front balancer gear. It is a side view of the back side balancer gear.

Explanation of symbols

10 Engine 14 Cylinder 16 Mission Chamber 33 Crankshaft 51 Front Balancer 52 Rear Balancer 37 Transmission 61 Freewheel Gear for Starter, Balancer Drive Gear 68 Starter Motor 69 Starter Motor Output Shaft 55 Balancer Shaft 59 Balancer Gear 45c Crank Gear

Claims (11)

In an engine balancer device equipped with a balancer that rotates with the rotational power of the crankshaft,
A starter motor for transmitting the starting power to the crankshaft to rotate the crankshaft;
A starter freewheel gear that transmits power from the output shaft to the crankshaft is provided between the crankshaft and the output shaft of the starter motor,
A balancer driving gear for transmitting power from the crankshaft to the balancer between the crankshaft and the balancer;
An engine balancer device, wherein the starter freewheel gear and the balancer driving gear are disposed on the same axis.   The balancer device for an engine according to claim 1, wherein the starter freewheel gear is also used as the balancer driving gear.   The shaft center of the starter freewheel gear and the balancer driving gear, the shaft center of the balancer, and the output shaft center of the starter motor are arranged in a triangular shape. Or the balancer apparatus of the engine of 2.   A line segment connecting the axis of the starter freewheel gear and the balancer driving gear and the output axis of the starter motor, the axis of the starter freewheel gear and the balancer driving gear, and the axis of the balancer The balancer device for an engine according to claim 3, wherein an intersection angle with a line segment connecting with the heart is an acute angle. A cylinder is disposed above the crankshaft, and a transmission is disposed behind the crankshaft.
The starter freewheel gear and the balancer driving gear are arranged behind the cylinder and above the transmission,
One of the starter motor and the balancer is disposed above the transmission behind the starter freewheel gear and the balancer driving gear, and the other is disposed above the starter freewheel gear and the balancer driving gear. The balancer device for an engine according to any one of claims 1 to 4, wherein the balancer device is disposed behind the cylinder. The balancer and another balancer that rotates with the rotational power of the crankshaft, and the other balancer receives power from the crankshaft via a transmission gear,
A mark for setting a rotational direction phase with respect to the other balancer is formed on the conduction gear, the conduction gear is molded, and the mark is molded simultaneously with the molding of the conduction gear. The balancer device for an engine according to any one of claims 1 to 5, wherein   For each balancer comprising the balancer and another balancer that is rotated by the rotational power of the crankshaft, both of the balancers are composed of the same parts, and the phase of the rotation direction is set to both the balancers. The engine balancer device according to claim 1, wherein the two marks are provided in different shapes. In an engine equipped with a balancer that rotates by the rotational power of the crankshaft,
A transmission gear for transmitting the rotational power of the crankshaft to the balancer; a mark for setting a phase in a rotation direction with respect to the balancer is formed on the transmission gear; and the transmission gear is molded, A balancer device for an engine, wherein a mark is formed simultaneously with the formation of the conductive gear. In an engine balancer device including two balancers rotating by the rotational power of a crankshaft,
Both balancers are composed of the same parts, and both the balancers are provided with two marks for each balancer for setting the phase in the rotational direction, and the two marks are in different forms. A balancer device for an engine.   A transmission gear for transmitting rotational power from the crankshaft to the balancer is provided, the conductive gear is formed with a mark for setting a phase in the rotational direction with respect to the balancer, and the transmission gear is molded. The balancer device for an engine according to claim 9, wherein the mark is molded simultaneously with the formation of the conductive gear. The balancer device for an engine according to claim 6, 8, or 10, wherein the transmission gear is molded integrally with a crankshaft.

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