JPH0348040A - Internal combustion engine balancer device - Google Patents

Abstract

PURPOSE:To reduce the number of parts of a drive means and to reduce the weight of the drive means by a method wherein the drive gear of the drive means for interlocking a secondary balancer weight with a crank shaft is located approaching the outer peripheral surface of the crank web of the crank shaft. CONSTITUTION:A drive gear 24a of a drive means 56 for interlocking a secondary balancer weight 13 with a crank shaft 1 is located approaching the outer peripheral surface of a crank web 24 of the crank shaft 1. This constitution causes the increase of the outer diameter of the drive gear 24a, enables rotation of the secondary balancer weight 13 at a speed two times as fast as that of the crank shaft 1 in a way to engage a gear 55 to be engaged with the drive gear not through an idle gear, forms the drive means 56 with the reduced number of part, and enables reduction of the size and the weight of the drive means.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a balancer device for an internal combustion engine.

(Prior art) A balancer device for an internal combustion engine reduces vibrations of the first order by rotating a second balancer weight in the opposite direction at the same speed as the crankshaft in order to reduce vibrations during operation of the internal combustion engine. However, in some cases, the secondary balancer weight is rotated at twice the speed of the crankshaft to reduce secondary vibrations.

This type of balancer device, especially a balancer device equipped with a secondary balancer weight, is known, for example, from Japanese Patent Application Laid-Open No. 58-20
The one disclosed in Japanese Patent No. 750 is known.

This balancer device fixes a secondary balancer weight to a balancer shaft rotatably supported parallel to the crankshaft.
A balancer driven gear mounted on the balancer shaft is meshed with a balancer drive gear mounted on the crankshaft via an idling gear, whereby the balancer shaft and the secondary balancer weight are rotated in conjunction with the crankshaft. ing. The driving gear and the driven gear are meshed with each other at a gear ratio of 2:1 via an idling gear so that the balancer weight can be rotated at twice the speed of the crankshaft.

However, in a balancer device with such a configuration, normally,
Since the crankshaft has a relatively large diameter crank web, it is necessary to provide a relatively large distance between the balancer shaft and the axis of the crankshaft.

For this reason, in the above balancer device, an idle gear is interposed between the balancer drive gear attached to the crankshaft and the balancer driven gear attached to the balancer shaft in order to mesh them at a gear ratio of 2:1. Therefore, the number of parts and the weight of the means for driving the secondary balancer weight increase, which hinders the reduction in weight and size of the internal combustion engine.

In addition, in such a balancer device, the balancer shaft, balancer drive gear, balancer driven gear, and idle gear are provided exclusively for the secondary balancer weight, so if a primary balancer weight is further provided, the It is necessary to separately set up a balancer shaft for the balancer weight and drive means such as a gear for interlocking the balancer shaft with the crankshaft.

However, if components such as the balancer shaft and drive means are set separately for each balancer weight, the number of parts for the entire balancer device increases, and the components of each balancer weight are not related to each other. This obstructs efforts to simplify the overall configuration of the balancer device, or to reduce its weight and size.

(Problems to be Solved) The present invention solves such inconveniences, and in a balancer device equipped with a secondary balancer weight, a driving means for interlocking the secondary balancer weight with the crankshaft is effectively connected to the crankshaft. It is an object of the present invention to provide a balancer device that can be used for various purposes, can be configured with a small number of parts, and can be made lighter and smaller.

In addition, in a balancer device equipped with a primary balancer weight in addition to a secondary balancer weight, the components related to each balancer weight can be effectively utilized by relating them to each other, and the number of parts can be reduced. The purpose of the present invention is to provide a balancer device that can perform the following functions.

Another object of the present invention is to provide a balancer device in which the weight of the drive means can be reduced, the driving means can be easily constructed, and the construction can be effectively utilized.

(Means for Solving the Problem) In order to achieve the above object, the balancer device for an internal combustion engine of the present invention includes a secondary balancer weight rotatably provided around a balancer shaft parallel to the crankshaft, and a secondary balancer weight that is rotatable around a balancer shaft parallel to the crankshaft. In a balancer device for an internal combustion engine, the drive means is provided to be rotatable around the balancer shaft together with the secondary balancer weight. The crankshaft is characterized by comprising a driven gear and a drive gear that is integrally rotatably provided in close proximity to the outer peripheral surface of one of the pair of crank webs of the crankshaft and is meshed with the driven gear.

The balancer shaft is interlocked with the crankshaft and is rotatably provided at a constant speed in the opposite direction, a primary balancer weight is rotatably provided integrally with the balancer shaft, and the secondary balancer weight is rotatably provided integrally with the balancer shaft. The balancer weight and the driven gear are integrally connected via a hollow shaft that is fitted onto the balancer shaft and rotatably supported around the balancer shaft.

Furthermore, the secondary balancer weight and the driven gear are provided at both ends of the hollow shaft, and the secondary balancer weight is close to a rotating surface of a connecting rod that connects the crankshaft and a piston of the internal combustion engine. The connecting rod is provided on the hollow shaft at a position such that the driving gear is provided at a position close to the connecting rod.

The balancer shaft also includes a second driven gear rotatably provided integrally with the balancer shaft, and a second driven gear rotatably provided integrally with the shaft of the crankshaft and meshed with the driven gear. It is characterized in that it is operatively connected to the crankshaft via a drive gear.

Furthermore, the second drive gear is a primary drive gear rotatably provided integrally with the crankshaft.

Moreover, the drive gear is formed on the outer peripheral surface of one of the pair of crank webs.

Further, the crankshaft is configured by connecting a crank half body having a crank web forming the drive gear and another crank half body having the other crank web via a crank pin. do.

Furthermore, the present invention is characterized in that a cam drive gear for driving a camshaft of an intake and exhaust system of an internal combustion engine is formed on the shaft portion of the crank half body having the crank web forming the drive gear.

Further, the cam drive gear is characterized in that the outer diameter of the cam drive gear is the same as or smaller than the outer diameter of the shaft portion of the crank half.

(Function) According to this means, since the drive gear of the drive means for rotating the secondary balancer weight in conjunction with the crankshaft is provided close to the outer peripheral surface of the crank web of the crankshaft, It becomes possible to form the drive gear with a large diameter, and there is no need to provide an idle gear or the like to increase the speed of the secondary balancer weight to twice the speed of the crankshaft.

When the balancer shaft is rotatably provided with the next balancer weight, and the secondary balancer weight and the driven gear are integrally connected via the hollow shaft, the hollow Since the shaft is rotatably supported on the balancer shaft, the balancer shaft is commonly used to rotatably support the primary balancer weight and the secondary balancer weight. At this time, the next balancer weight is rotated integrally with the balancer shaft in the opposite direction at the same speed as the crankshaft, and the second balancer weight is rotated integrally with the hollow shaft at twice the speed relative to the crankshaft. being rotated in opposite directions, the secondary balancer weight and the hollow shaft are rotated in the same direction with respect to the balancer axis and the -next balancer weight;
- Therefore, the relative rotational speed difference between the balancer shaft and the hollow shaft is significantly reduced, and it becomes possible to use a needle bearing or the like inserted between them with a relatively small capacity.

Furthermore, the secondary balancer weight and the driven gear are provided at both ends of the hollow shaft, and the secondary balancer weight is provided on the hollow shaft at a position close to the rotating surface of the connecting rod, and the When the drive gear is located close to the connecting rod, the secondary balancer weight rotates close to the rotating surface of the connecting rod, so that the couple due to the inertial force generated during the rotation is reduced. The weight is reduced to a negligible level, and the distance between the secondary balancer weight and the driven gear is reduced, so the length of the hollow shaft is shortened, the weight of the hollow shaft is reduced, and its rigidity is improved. .

The balancer shaft also includes a second driven gear rotatably provided integrally with the balancer shaft, and a second driven gear rotatably provided integrally with the shaft of the crankshaft and meshed with the driven gear. when the gear ratio of the drive gear and the driven gear is 2:1, and the gear ratio of the second drive gear and the second driven gear is Since the ratio is 1:1, the small-diameter driven gear and the large-diameter second driven gear on the balancer shaft side mesh with the large-diameter drive gear and the small-diameter second drive gear on the crankshaft side, respectively. , the distance between the crankshaft and the balancer shaft becomes smaller.

Furthermore, when the second drive gear is the primary drive gear, there is no need to provide the second drive gear independently on the crankshaft, which reduces the number of parts of the balancer device and shortens the crankshaft. It becomes possible to aim for.

Furthermore, when the drive gear is formed on the outer peripheral surface of one of the pair of crank webs, only the teeth of the drive gear need be formed on the outer peripheral surface of the crank web, so the weight of the drive gear is reduced. Ru.

Furthermore, when the crankshaft is composed of a pair of crank halves, the drive gear can be easily formed by forming the drive gear on the crank web of one crank half with both crank halves separated. Ru.

Furthermore, when the crankshaft is composed of a pair of crank halves, the cam drive gear can be easily formed by forming the cam drive gear on the shaft of one of the crank halves while the two crank halves are separated. be done.

Furthermore, when the outer diameter of the cam drive gear is the same as or smaller than the outer diameter of the shaft of the crank half, in order to rotatably support the crankshaft on the crankcase, etc., It is possible to use a conventional ball bearing and insert it onto the shaft of the crankshaft.

(Example) A single-cylinder four-stroke engine for a motorcycle equipped with an example of the balancer device for an internal combustion engine of the present invention will be described with reference to FIGS. 1 to 4. 1 to 3 are explanatory cross-sectional views of main parts of the engine in a front view, a plan view, and a side view, respectively, and FIG. 4 is a cross-sectional view taken along the line ■■ in FIG. 3.

In Figs. 1 to 3, 1 is a crankshaft rotatably supported by a crankcase 2, and 3 is a crankshaft rotatably supported by the crankcase 2 and connected to each other via a transmission gear train 4. A transmission device includes a main shaft 5 and a subshaft 6; 7 is a clutch device mounted on the main shaft 5 of the transmission 3 outside the crankcase 2; 8a is a clutch device mounted on the main shaft 5 and a subshaft 6 inside the crankcase 2;
A balancer device comprising a primary balancer weight 9 and a secondary balancer weight 10, each of which is rotatably provided around the crankcase 2; A balancer device which is a main part of the present invention is equipped with a primary balancer weight 12 and a secondary balancer weight 13 that are freely provided. 14 is a piston that is slidable inside a cylinder block 15 mounted on the crankcase 2. , 16 is a speed change drive device installed in the crankcase 2 to drive the transmission 3, and I7 is installed on the cylinder block 15 to form a combustion chamber 18 between it and the piston 14 and communicate with the combustion chamber 18. A cylinder head equipped with an intake/exhaust passage (not shown); reference numeral 19 is an intake/exhaust device provided in a head cover 20 mounted on the cylinder rad 1f for intake/exhaust into the combustion chamber 18;
21 is a generator mounted on the end of the crankshaft l outside the crankcase 2. Further, in FIG. 4, 22 is a kink starter provided in the crankcase 2 for starting the engine.

As shown in the first diagram, the crankshaft l has a pair of crank webs 23.24 housed in the crankcase 2, and shaft portions 1a, lb on both sides of the crank webs 23.24.
is rotatably supported by the crankcase 2 via bear links 25 and 26. This crankshaft l is a crank half body 27 having a crank web 23 and a shaft portion 1a.
and a crank half body 28 having a crank web 24 and a shaft portion 1b, which are integrally connected via a crank pin 29 formed integrally with the crank web 23 and press-fitted into the crank web 24. The crank pin 29 is connected to the piston mower 4 via the connecting rod 3o, and as the piston 14 moves up and down, the crankshaft l is rotated about its axis. Further, the end face of the crankcase 2 side of the portion of the crank web 23 where the crank pin 29 is provided is cut into a slanted rod and made thin, thereby forming a space between it and the crankcase 2.

As shown in the first diagram, the main shaft 5 of the transmission 3 is rotatably supported by the crankcase 2 via bearings 31 and 32, is provided parallel to the crankshaft 1, and projects from the inside of the crankcase 2. The clutch device 7 is connected to the end.

As shown in the second diagram, the clutch device 7 includes a clutch outer 33 that is placed close to the crankcase 2 and inserted around the end of the main shaft 5, and a clutch outer 33 that is housed inside and rotates integrally with the main shaft 5. A clutch inner 34 is freely attached, and these include a plurality of clutch plates 3 which are overlapped and pressed together between the clutch inner 34 and a lifter plate 35.
It can be rotated concentrically and integrally with the main shaft 5 via a shaft 6. On the end face of the clutch outer 33 on the crankcase 2 side, a primary drive gear 37 is rotatably attached to the end of the shaft portion 1a of the crankshaft I that protrudes from inside the crankcase 2. A primary driven gear 38 meshed with the main shaft 5 at a gear ratio of 1:1 is fixed concentrically with the main shaft 5, and the primary driven gear 38 is rotatably fitted onto the main shaft 5 via a needle bearing 39. A hollow shaft 40 interposed between the real shaft 5 and the bearing 32
The crank case 2 is rotatably fitted to the outer peripheral surface of the end protruding from inside the crank case 2 by spline connection.

Therefore, when the crankshaft 1 is rotated as described above,
The clutch outer 33 and the hollow shaft 4° rotate around the axis of the main shaft 5 at the same speed and in the opposite direction to the crankshaft l via the primary drive gear 37 and the primary driven gear 38, and are pressed together and pressed together. The clutch inner 34 and main shaft 5 are connected to the clutch outer 3 via a plurality of clutch plates 36.
3 and the hollow shaft 4o, it rotates around its axis.

As shown in the first figure, the clutch device 7 includes a bushing rod 41 that is slidably inserted into the main shaft 5 toward the lifter plate 35. The bushing rod 41 is connected to the lifter plate 35 by a clutch drive device (not shown). The clutch plate 3G is released from the mutually pressed state by sliding the inner member 34 in a direction away from the inner member 34, and when the clutch plate 3G is released, the clutch device 7 is in a disconnected state and the clutch inner member 34 and the main shaft 5 are rotated. do not.

As shown in the first diagram, the subshaft 6 of the transmission 3 is rotatably supported by the crankcase 2 through bearings 42, 43 and is provided parallel to the crankshaft I, and the subshaft 6 of the transmission 3 is provided in parallel to the crankshaft I. It is connected to the main shaft 5 via a gear train 4, and rotates in conjunction with the main shaft 5 at several speeds depending on the meshing combination of the transmission gear train 4, similar to known transmission devices. . A drive sprocket 44 is rotatably attached to the end of the countershaft 6 protruding from inside the crankcase 2, and the drive sprocket 44 is connected to a wheel (not shown) via a chain 45. , the rotation of the subshaft 6 is transmitted to the wheels.

Therefore, the driving force of the engine accompanying the vertical movement of the piston 14 is transmitted to the crankshaft 1, the clutch device 7, and the transmission device 3.
The signal is output from the subshaft 6 of the transmission 3 to the wheels via the auxiliary shaft 6 of the transmission 3 in sequence.

The primary balancer weight 9 (hereinafter referred to as the "secondary balancer 9") of the balancer device 8a is provided integrally with the end of the hollow shaft 40 inside the crankcase 2, as shown in the second figure. The main shaft 5 is integrally connected to the shaft 40 and the clutch outer 33 at the same speed as the crankshaft 1 and in the opposite direction.
It is said to be able to rotate freely around the axis. A drive gear 46 for rotating the secondary balancer weight 10 (hereinafter referred to as secondary balancer 10) around the secondary balancer 6 is located between the secondary balancer 9 and the crankcase 2. It is provided integrally with the hollow shaft 40.

The secondary balancer 9 and the drive gear 46 are provided on the crank web 23 and the crankcase 2 as close as possible to each other so that the hollow shaft 40 does not become unnecessarily long. When the crankshaft 1 rotates 180 degrees from the state shown in the second figure, the drive gear 46 is positioned in the space formed between the crank web 23 and the crankcase 2, as shown by the imaginary line in the figure. However, the crank web 23 and the drive gear 46 are constructed so as not to interfere with each other.

The secondary balancer 10 has one end portion of a hollow shaft 48 which is rotatably fitted onto the secondary shaft 6 via a needle bearing 47 at a position facing the hollow shaft 40 within the crankcase 2, as shown in the second figure. A driven gear 49 is integrally provided at the other end of the hollow shaft 48 and is meshed with the drive gear 46 at a gear ratio of 2:1.

Therefore, when the crankshaft 1 rotates as described above, the -order balancer 9 rotates around the main shaft 5 integrally with the hollow shaft 40 at the same speed as the crankshaft 1 and in the opposite direction, as shown in the third figure. Meanwhile, the secondary balancer 10 is rotated about the subshaft 6 at twice the speed and in the same direction as the crankshaft 1 via the drive gear 46 and the driven gear 49. The secondary balancer 10 and the driven gear 49 are arranged so that during this rotation, the primary balancer 9 is located between the secondary balancer 10 and the driven gear 49, as shown by the imaginary line in FIG. is provided on the hollow shaft 48, thereby preventing the hollow shaft 48 from becoming longer than necessary.

On the other hand, the balancer shaft 11 of the balancer device 8b, which is a main part of the present invention, is provided parallel to the crankshaft 1 at a position facing the main shaft 5 with the crankshaft 1 sandwiched therebetween, as shown in the second figure. is rotatably supported via bearings 50 and 51.

Then, the primary balancer weight 1 of the balancer device 8b
2 (hereinafter referred to as the -order balancer 12) includes a main balancer 12a that is integrally provided at the end of the balancer shaft 11 inside the crankcase 2, as shown in FIGS. 2 and 3, and a crankcase of the balancer shaft 11. A sub-balancer 12b is integrally provided with a driven gear 52 which is rotatably attached to an end protruding from the inside of the main drive gear 52 and meshes with the primary drive gear 37 at a gear ratio of 1:1. balancer 12
a carries most of the weight of the primary balancer 12, and the sub-balancer 12b carries the remaining weight.

In addition, the secondary balancer weight 13 (hereinafter referred to as secondary balancer 13) of the balancer device 8b is inserted into the middle part of the balancer shaft 11 in the crankcase 2, as shown in FIGS. It is integrally provided at one end of a hollow shaft 54 which is rotatably supported via a hair ring 53. This hollow shaft 511 has a driven gear 55 integrally provided at its other end, and a drive gear 24a formed on the outer peripheral surface of the crank web 24 and meshed with the driven gear 55 at a gear ratio of 1:2. It is connected to the crankshaft 1 via a drive means 56 consisting of. The drive gear 24a is located close to the connecting rod 30, and the secondary balancer 13 and driven gear 55 provided on the hollow shaft 54 are located close to the rotating surface of the connecting rod 30.

Therefore, when the crankshaft 1 rotates, as shown in FIG. On the other hand, the secondary balancer 13 is rotated integrally with the hollow shaft 54 through the driving gear 24a and the driven gear 55 of the driving means 56 at twice the speed and in the opposite direction with respect to the crankshaft 1. Rotated around axis 110.

In this way, in this engine, the primary balancer 9 of the balancer device 8a and the primary balancer 2 of the balancer device 8b are interlocked with the crankshaft 1 and rotated at the same speed and in the opposite direction. The primary vibration is reduced, and the secondary balancer 10 of the balancer device W8a and the secondary balancer 13 of the balancer device 8b are rotated at twice the speed in conjunction with the crankshaft 1, and in the same direction as the crankshaft l. By rotating the engine in the opposite direction, secondary vibrations of the engine are reduced.

In addition, the primary balancer 9.12 of each balancer unit W8a, 8b
As shown in FIGS. 2 and 3, the cotton connecting the respective rotation centers is connected to both crank webs 2 of the crankshaft 1.
3.24, in other words, at a position where the distance from the center point ○ is -, so that the crankshaft 1 is
The moments generated around the center point 0 are made to cancel each other out.

As shown in the first diagram, the variable speed drive device 16 includes a spindle 57 rotatably supported on one side of the crankcase 2 and a shift drum 58 rotatably supported on the crankcase 2. The crankcase 2 is provided with a plurality of shift forks 60 slidably fitted to a shift fork shaft 59 supported in parallel with the main shaft 5 and the counter shaft 6, and each shift fork 60 is shown in FIGS. As shown, the first gear is engaged with the transmission gear train 4 of the transmission device 3, and
As shown in the figure, it is engaged with a guide groove 58a formed on the outer peripheral surface of the shift drum 58. As shown in FIGS. 1 and 3, the shift drum 58 is engaged with the spindle S7 via a link arm 61 rotatably attached to the end of the spindle 57 in the crankcase 2. , is rotated by the swinging of the link arm 61 as the spindle 57 rotates. The shift drum 58 is
As shown in the first diagram, a stopper 6 whose end protrudes from inside the crankcase 2 is provided on the outside of the crankcase 2.
2, and its rotation is performed in stages.

In this variable speed drive device I6, as shown in FIG. 1, the link arm 61 is operated by operating a speed change pedal (not shown) connected to the end of the spindle 57 protruding from inside the crankcase 2, as in the known variable speed drive device. The shift drum 58 is rotated in stages through the shift drum 58, and at this time, each shift fork 60 is guided by the guide groove 58a of the shift drum 58 and slides on the shift fork shaft 59 in its axial direction, thereby changing the speed change gear train. Some transmission gears of 4 are connected to main shaft 5
Alternatively, by moving the subshaft 6 in the axial direction, the meshing combination of the transmission gear train 4 is changed, so that the rotation transmission from the main shaft 5 to the subshaft 6 is changed.

The spindle 57 is returned to its original position after being rotated a predetermined amount by a return spring 63 provided at an end inside the crankcase 2.

As shown in the first diagram, the generator 21 is rotatably attached to the end of the crank half 28 of the crankshaft 1 protruding from inside the crankcase 2 on the opposite side from the clutch device 7. A stator 66 is fixed to the inner surface of a generator cover 65 attached to the crankcase 2 and housed in the flywheel 64. Similar to known generators, the crankshaft 1 rotates. When the motor moves, the flywheel 64 rotates together with the crankshaft 1 around the stator 66 to generate electricity, and the dirt charges a battery (not shown).

The intake/exhaust device 19 includes a bearing 6 between the cylinder head I7 and the head cover 20 as shown in the first diagram.
7, 68, and a plurality of rocker arms 71, which are rotatably supported by a rocker arm shaft 70 provided on the hend cover 20 in parallel with the cam shaft 69. A cam driven sprocket 72 rotatably attached to the end of the camshaft 69 is formed on the shaft portion 1b of the clutch half body 28 at a position between the generator 21 and the crankcase 2. The chain 7 is attached to a cam drive sprocket 73 provided on the outer peripheral surface of the small diameter portion 28a.
4, whereby the camshaft 69 is rotated as the crankshaft 1 rotates. Each rocker arm 71 is engaged with a cam 69a formed on the camshaft 69, and is also engaged with an intake and exhaust valve (not shown) that opens and closes an intake and exhaust passage communicating with the combustion chamber 18.

Further, the outer diameter of the cam drive sprocket 73 is set to be the same as the diameter of the shaft portion 1b supported by the hair ring 26.

In this intake/exhaust device 19, similar to known engines,
The rotation of the camshaft 69 in synchronization with the crankshaft 1 opens and closes the intake and exhaust valves via the rocker arm 32, thereby performing intake and exhaust air into the combustion chamber I8.

The kick starter 22 includes a crankcase 2 and a clutch cover attached to the crankcase 2, as shown in the fourth figure.
starter spindle 76 rotatably supported by 75 and 75;
and a starter gear 77 rotatably supported in the intermediate portion of the starter pin truer G in the crankcase 2, and the starter gear 7G is connected to the center of the hollow shaft 48 having the secondary balancer 10. It meshes with the driven gear 49, and a ratchet portion 77a is formed on its end face on the clutch cover 75 side. At a position between the starter gear 77 and the clutch cover 75, there is a drive ratchet which is rotatably and slidably fitted integrally with the starter spindle 76 and biased in a direction away from the ratchet portion 77a. 78 are provided.

In such a kick starter 22, the starter spindle 7
6 is connected to the kick pedal outside the clutch cover 75 (
by operating the drive ratchet 78 (not shown).
slides and is engaged with the ratchet portion 77a of the starter gear 77, and the starter spindle 76 is rotated together with the drive ratchet 78, whereby the starter gear 77 is rotated and the hollow shaft 48 is rotated. . At this time, the hollow shaft 4g rotates in the same direction in conjunction with the crankshaft load as described above, thereby moving the piston 14 up and down and starting the engine.

The starter spindle 76 is returned to its original position after being rotated a predetermined amount by a return spring 79 provided at an end inside the crankcase 2 .

Next, in the engine having such a structure, the above-mentioned structure of the balancer device 8b, which is a main part of the present invention, will be explained with reference to FIG.

In this balancer device 8b, a driving means 56 for rotating the secondary balancer 13 in conjunction with the crankshaft 1
Since the driving gear 24a is formed on the outer circumferential surface of the crank web 24 and has a large diameter, the driving gear 24a is
The secondary balancer 13 can be rotated at twice the speed of the crankshaft 1 by meshing with the driven gear 55, and the number of parts of the balancer device 8b is reduced. Since only the teeth of the drive gear 24a are formed on the outer peripheral surface of the crank web 24, its weight is reduced.

Further, the secondary balancer 13 is supported via the hollow shaft 54 by the balancer shaft 11, which is integrally provided with the negative balancer 12. It is shared as the rotation axis,
The number of components of the balancer device 8b is reduced.

Furthermore, as a drive gear for rotating the -order balancer 12 and balancer shaft 11 via the driven gear 52, the primary drive gear 3 is not provided independently on the crankshaft.
7, the number of components of the balancer device 8b is reduced.

The balancer shaft 11 provided with the secondary balancer 12 rotates in the opposite direction at the same speed as the crankshaft l as described above, and the hollow shaft 54 provided with the secondary balancer 13 rotates in the opposite direction to the crankshaft 1 as described above. balancer shaft 1 in the opposite direction at twice the speed.
1, the hollow shaft 54 rotates around the balancer shaft 1.
As the needle bearing 53, the needle bearing 53 rotates in the same direction with respect to the balancer shaft 11, so that the relative rotational speed difference between the hollow shaft 54 and the balancer shaft 11 is significantly reduced, and the hollow shaft 54 is supported on the balancer shaft 11. One with a small capacity can be used.

Further, as described above, since the secondary balancer 13 and the driven gear 55 provided at both ends of the hollow shaft 54 are provided close to the rotating surface of the connecting rod 30, when the secondary balancer 13 rotates, The force couple due to the generated inertial force is so small that it can be ignored (and the length of the hollow shaft 54 is shortened to achieve miniaturization, and the rigidity of the hollow shaft 54 is improved. It is possible to reduce the weight by making it compact.

Further, as described above, a driving gear 24a and a driven gear 55 for interlocking the secondary balancer 13 with the crankshaft 1 are provided.
Since the gear ratio of the primary drive gear 37 and the driven gear 52 for interlocking the -order balancer 12 with the crankshaft 1 is I:I, the small-diameter driven gear 55 on the balancer shaft 11 side Since the large-diameter drive gear 24a and the small-diameter primary drive gear 37 on the crankshaft 1 side are engaged with the large-diameter driven gear 52, respectively, the distance between the crankshaft 1 and the balancer shaft 11 is reduced. Therefore, the engine is made smaller.

Further, the crankshaft l is connected to the crank web 2 as described above.
3, and the crank half 28, which has the crank web 24, it is possible to process them separately. The drive sprocket 73 can be easily formed, and in particular, when forming the drive gear 24a, its strength can be improved by carburizing or other processes without enlarging its tooth width.

As described above, since the outer diameter of the cam drive sprocket 73 is the same as the outer diameter of the shaft portion 1b of the crankshaft 1,
The bearing 26 can be inserted onto the cough shaft portion 1b without any problem, and therefore a relatively inexpensive ball hair ring can be used as the bearing 26. At this time,
Of course, the outer diameter of the cam drive sprocket 73 may be made smaller than the outer diameter of the shaft portion 1b of the crankshaft 1.

In this embodiment, the primary balancer 1 of the balancer device 8b is
2 is configured to consist of a main balancer 12a and a sub-balancer 12b, but it goes without saying that the sub-balancer 12b may be provided integrally with the main balancer 12a instead of being provided on the driven gear 52.

Next, another example of the balancer device of the present invention will be explained with reference to FIG. FIG. 5 is an explanatory cross-sectional view of the main parts of a single-cylinder engine for a motorcycle.

This engine has the same basic configuration as the above-described engine, and includes a balancer device 8a including a -order balancer 9 and a secondary balancer 10, and a main part of the present invention including a -order balancer 12 and a secondary balancer 13. The primary balancer 9 and secondary balancer IO of the balancer device 8a are connected to the main shaft 5 and counter shaft 6 of the transmission 3 via hollow shafts 40.48, respectively, similarly to the engine described above. The primary balancer 9 is rotatably supported on the crankshaft 1 by a primary drive gear 37 and a primary driven gear 38.
The secondary balancer 10 rotates together with the hollow shaft 40 by interlocking the clutch device 7 with the flange outer 33 of the clutch device 7.
is interlocked with the hollow shaft 40 via a driving gear 46 and a driven gear 49 so as to rotate together with the hollow shaft 48.

On the other hand, the primary balancer 12 of the balancer device 8b, which is a main part of the present invention, consists only of the main balancer, and is integrally attached to the end of the balancer shaft 11 rotatably supported on the crankcase 2, similar to the engine described above. The secondary balancer 12 is moved to the balancer shaft 11 by meshing with the primary drive gear 37 and the driven gear 52 attached to the end of the balancer shaft 11 protruding outside the crankcase 2 at a gear ratio of 1:1.
At the same time, it is linked to the crankshaft 1 so that it rotates at the same speed and in the opposite direction.

Further, the secondary balancer 13 of the balancer device 8b is provided integrally with the hollow shaft 54 rotatably supported on the balancer shaft 11 at a position close to the rotating surface of the connecting rod 30, similar to the engine described above. The secondary balancer 13 is rotated together with the hollow shaft 54 in conjunction with the crankshaft 1 by a drive means 56' having a different configuration from the drive means 56.

This driving means 56'' is arranged between a driven gear 80, which is integrally provided at the end of the hollow shaft 54, a crank web 23, which is integrally provided with a crank pin 29, and the crank case 2. It consists of a drive gear 81 that is integrally and rotatably fixed to the shaft portion 1a of the shaft 1, and the drive gear 81 is formed to have a large diameter between the outer diameter of the crank web 23 and the outer diameter between the tracks, and is connected to the driven gear 80. The secondary balancer 13 and the hollow shaft 5 are meshed with each other at a gear ratio of 2:1.
4 is rotated in the opposite direction at twice the speed of the crankshaft 1.

Therefore, in the balancer device 8b having such a configuration, similarly to the above-mentioned engine, the drive gear 81 of the drive means 56' is provided close to the crank web 23 and has a large outer diameter between the crank web 23 and the road. The secondary balancer 13 can be rotated at twice the speed of the crankshaft 1 by the driving gear 81 and the driven gear 80 without using an idle gear, and the number of parts of the balancer device 8b is reduced.

Further, the secondary balancer 13 is supported via the hollow shaft 54 on the balancer shaft 11 which is integrally provided with the -order balancer 12, so that the balancer shaft 11 is the rotation axis of the primary balancer 12 and the secondary balancer 13. It is shared as a core, thereby reducing the number of components of the balancer device 8b.

Furthermore, as a drive gear for rotating the -order balancer 12 and balancer shaft 11 via the driven gear 52, the primary drive gear 3 is not provided independently on the crankshaft.
7, the number of components of the balancer device 8b is reduced.

The balancer shaft 11 provided with the -order balancer 12 rotates in the opposite direction at the same speed as the crankshaft 1, and the secondary/S balancer 1
3 rotates around the balancer shaft 11 in the opposite direction at twice the speed of the crankshaft 1, the hollow shaft 54 rotates in the same direction with respect to the balancer shaft 11, and therefore The relative rotational speed difference between the hollow shaft 54 and the balancer shaft 11 is reduced, and a needle bearing 53 with a small capacity can be used for supporting the hollow shaft 54 on the balancer shaft 11.

Further, as described above, since the secondary balancer 13 and the driven gear 55 provided at both ends of the hollow shaft 54 are provided close to the rotating surface of the connecting rod 30, when the secondary balancer 13 rotates, The force couple caused by the generated inertial force is reduced to a negligible extent, the length of the hollow shaft 54 is shortened, and the size of the hollow shaft 54 is reduced, and the rigidity of the hollow shaft 54 is improved. As a connomact item, it can be made lightweight.

Further, as described above, a driving gear 81 and a driven gear 80 are provided for interlocking the secondary nozzle lancer 13 with the crankshaft 1.
Since the gear ratio of the primary drive gear 37 and the driven gear 52 for interlocking the -order balancer 12 with the crankshaft 1 is 1:1, the small-diameter driven gear 81 on the balancer shaft ll side Since the large-diameter drive gear 80 and the small-diameter primary drive gear 37 on the crankshaft 1 side are meshed with the large-diameter driven gear 52, respectively, the distance between the crankshaft 1 and the balancer shaft 11 is reduced. Therefore, the engine is made smaller.

In addition, in this engine, the balancer shaft 1 is
A cam drive sprocket 82 is integrally rotatably attached to the end protruding from the inside of the crankcase 2 of 1, and a camshaft of an intake/exhaust device (not shown) is driven from the cam drive sprocket 82 via a chain 83. ing.

Further, this engine includes a variable speed drive device 16 and a generator 21 having the same configuration as the above-mentioned engine.

(Effects) As is clear from the above description, according to the balancer device for an internal combustion engine of the present invention, the drive gear of the drive means for interlocking the secondary balancer weight with the crankshaft is attached to the outer peripheral surface of the crank web of the crankshaft. By arranging the drive gear close to the drive gear, the outer diameter of the drive gear is made large, and the driven gear is directly meshed with the drive gear without going through an idle gear, thereby allowing the secondary balancer to operate at twice the speed of the crankshaft. It is possible to rotate the driving means, and the driving means can be constructed with a small number of parts, thereby making it possible to reduce the weight and size of the driving means.

Then, the secondary balancer weight and the driven gear of the driving means are integrally connected via a hollow shaft rotatably supported by a balancer shaft on which the next balancer weight is rotatably provided. By doing so, the balancer shaft can be
It can be used commonly as the rotation axis of the lancer weight, and the number of parts of the balancer device can be reduced. Also,
At this time, the balancer shaft and the hollow shaft are rotated in the same direction, and the relative rotational speed difference between them is greatly reduced.
In order to rotatably support the hollow shaft on the balancer shaft, a small-capacity, inexpensive hair ring can be used, and the manufacturing cost of the internal combustion engine can be reduced.

Further, a secondary balancer weight and a driven gear are provided at both ends of the hollow shaft, and the secondary balancer weight is provided at a position close to the rotating surface of the connecting rod,
By providing the drive gear close to the connecting rod, the hollow shaft becomes shorter and lighter, and its rigidity can be improved, making it possible to reduce the weight of the balancer device. Further, at this time, since the secondary balancer weight rotates at a position close to the rotating surface of the connecting rod, it is possible to reduce the couple due to the inertial force generated at the time of the rotation.

In addition, by connecting the balancer shaft to the crankshaft via a second driven gear provided thereon and a second drive gear provided to the crankshaft, the large-diameter drive gear and the small-diameter drive gear on the crankshaft side can be connected. By meshing the small-diameter driven gear and the large-diameter second driven gear on the balancer shaft side with the second drive gear of the internal combustion engine, the interval between the crankshaft and the balancer shaft can be reduced. can be made smaller.

Furthermore, by using a primary drive gear as the second drive gear, there is no need to provide the second drive gear independently on the crankshaft, and the number of parts of the balancer device can be reduced. It is possible to shorten the time.

Furthermore, by forming the drive gear of the drive means on the outer circumferential surface of one of the pair of crank webs, only the teeth of the drive gear are formed on the outer circumferential surface of the crank web.
The weight of the drive gear is reduced, and the weight of the balancer device can be reduced.

Furthermore, when the crankshaft consists of a pair of crank halves, by forming the drive gear on the crank web in a separated state, the formation work can be easily performed and the processing cost can be reduced. I can do it.

Furthermore, at this time, it is also possible to easily form the cam drive sprocket on one of the crank halves in a separated state.

Furthermore, when the outer diameter of the cam drive sprocket is the same as or smaller than the outer diameter of the shaft of the crank half, an ordinary inexpensive ball hair ring is used to rotatably support the crankshaft. It can be used by being attached to the shaft portion, and the manufacturing cost of the internal combustion engine can be reduced.

[Brief explanation of drawings]

1 to 3 are explanatory cross-sectional views of main parts of an engine provided with an example of the balancer device of the present invention in a front view, a plan view, and a side view, respectively, and FIG. 4 is an explanatory sectional view taken along the line IV-IV in FIG. 3. 5 is an explanatory sectional view of an engine equipped with another example of the balancer device of the present invention. 1... Crankshaft 1a, Ib... Shaft portion 8b
... Balancer device 11 ... Balancer shaft 12 ...
-Next balancer weight 13...Secondary balancer weights 23, 24...Crank webs 24a, 81...Drive gear 27.28...Crank half body 29...Crank pin 30... Connecting rod 37...second drive gear (primary drive gear) 52
...Second driven gear 54...Hollow shafts 55, 80
... Driven gear 56 ... Drive means 73 ... Cam drive sprocket

Claims (1)

[Claims] 1. A secondary balancer weight rotatably provided around a balancer shaft parallel to the crankshaft, and a drive means for rotating the balancer weight in conjunction with the crankshaft. In the balancer device for an internal combustion engine, the driving means includes a driven gear rotatably provided around the balancer shaft integrally with the secondary balancer weight, and an outer periphery of one of the pair of crank webs of the crankshaft. 1. A balancer device for an internal combustion engine, comprising a driving gear that is rotatably provided in close proximity to a surface and meshed with the driven gear. 2. The balancer shaft is provided so as to be rotatable in the opposite direction at a constant speed in conjunction with the crankshaft, and a primary balancer weight is rotatably provided integrally with the balancer shaft; 2. The internal combustion engine according to claim 1, wherein the balancer weight and the driven gear are integrally connected via a hollow shaft that is fitted onto the balancer shaft and is rotatably supported around the balancer shaft. balancer device. 3. The secondary balancer weight and the driven gear are provided at both ends of the hollow shaft, and the secondary balancer weight is close to a rotating surface of a connecting rod that connects the crankshaft and the piston of the internal combustion engine. 3. The balancer device for an internal combustion engine according to claim 2, wherein the drive gear is provided on the hollow shaft at a position close to the connecting rod. 4. A second driven gear that is rotatably provided on the balancer shaft integrally with the balancer shaft; and a second driven gear that is rotatably provided on the shaft portion of the crankshaft and meshes with the driven gear. 3. The balancer device for an internal combustion engine according to claim 2, wherein the balancer device is operatively connected to the crankshaft via a drive gear. 5. The balancer device for an internal combustion engine according to claim 4, wherein the second drive gear is a primary drive gear rotatably provided integrally with the crankshaft. 6. The balancer device for an internal combustion engine according to claim 1, wherein the drive gear is formed on an outer peripheral surface of one of the pair of crank webs. 7. The crankshaft is configured by connecting a crank half body having a crank web forming the driving gear and another crank half body having a crank web via a crank pin. The balancer device for an internal combustion engine according to claim 6. 8. A cam drive sprocket for driving a camshaft of an intake/exhaust device of an internal combustion engine is formed on the shaft of the crank half having the crank web forming the drive gear. Balancer device for internal combustion engines. 9. The balancer device for an internal combustion engine according to claim 8, wherein the outer diameter of the cam drive gear is equal to or smaller than the outer diameter of the shaft portion of the crank half.