JPH04370441A - Balancer device of internal combustion engine - Google Patents

Abstract

PURPOSE:To miniaturize a side cover of an internal combustion engine, in which a balancer device is housed inside a crank case. CONSTITUTION:Primary balancer gears 36, 29, which drive a front primary balancer IF1 installed in a balancer shaft 26, are arranged between a balance weight part 10a and a bearing 9 on one side of a crankshaft 10, while secondary balancer gears 30, 31, which drive front secondary balancers IF2, MF2 installed in the balancer shaft 26, are arranged between the balance weight part 10a and a bearing 8 on the other side. Since the primary balancer gears 36, 29 and the secondary balancer gears 30, 31 are accommodated inside a crank case 1 while being balanced right and left with respect to the balance weight part 10a, side covers 6, 7 can be miniaturized. A cooling water pump 27 is directly attached to the right end of the balancer shaft 26 and covered with a pump cover 5.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a balancer device for reducing vibrations in an internal combustion engine, and in particular to a crankshaft in which both sides of a balance weight part in the axial direction are supported by a pair of bearings in a crankcase, and a balancer device parallel to the crankshaft. a balancer shaft supported on the crankcase, a primary balancer and a secondary balancer supported on the balancer shaft, a primary balancer gear that transmits rotation of the crankshaft to the primary balancer, and a crankshaft to the secondary balancer. Transmits the rotation of 2
The present invention relates to a balancer device for an internal combustion engine, which includes a secondary balancer gear and a side cover that covers the side of the crankcase.

0002

2. Description of the Related Art Such a balancer device for an internal combustion engine has already been proposed by the present applicant in Japanese Patent Application No. 2-280152.

0003

[Problems to be Solved by the Invention] In the above conventional balancer device for an internal combustion engine, the primary balancer gear that drives the primary balancer on the front balancer shaft is disposed outside the side wall of the crankcase. Moreover, since the shaft of the cooling water pump is connected to the outer end of the primary balancer gear provided on the front balancer shaft,
There is a problem in that the side cover that covers the primary balancer gear and the cooling water pump becomes larger, which causes the overall size of the internal combustion engine to become larger.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to reduce the size of a side cover of an internal combustion engine by appropriately arranging a balancer gear and a cooling water pump.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a crankshaft in which both sides of a balance weight part in the axial direction are supported by a crankcase by a pair of bearings, and a crankcase in parallel with the crankshaft. a balancer shaft supported on the balancer shaft, a primary balancer and a secondary balancer supported on the balancer shaft, a primary balancer gear that transmits the rotation of the crankshaft to the primary balancer, and a primary balancer gear that transmits the rotation of the crankshaft to the secondary balancer. A secondary balancer gear that transmits
In the balancer device for an internal combustion engine, which includes a side cover that covers the side of the crankcase, a primary balancer gear is disposed between the balance weight portion of the crankshaft and the one bearing, and a secondary balancer gear is arranged between the crankshaft balancer gear and the side cover that covers the side of the crankcase. The first feature is that it is disposed between the balance weight portion of the shaft and the other bearing.

[0006] In addition to the above-mentioned first feature, the present invention also has the following features:
A second feature is that a cooling water pump is provided at the shaft end of the balancer shaft that projects outside from the crankcase, and the cooling water pump is covered with a pump cover that is attached to the outer surface of the crankcase.

[0007]

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings.

1 to 4 show one embodiment of the present invention, FIG. 1 is a schematic diagram of the internal combustion engine (cross-sectional view taken along the line 1-1 in FIG. 4), and FIG. 2 is an enlarged view of two parts of FIG. 3 are enlarged views of three parts of FIG. 1, and FIG. 4 is a sectional view taken along the line 4-4 of FIG.

A crankcase 1 of a single-cylinder, four-stroke internal combustion engine E for a motorcycle is divided into a right half 2 and a left half 3, and a cylinder block 4 is connected to the upper part of the crankcase 1. A right side cover 6 is coupled to the outer split surface 2a of the right half 2 of the crankcase 1, and a left side cover 7 is coupled to the outer split surface 3a of the left half 3 of the crankcase 1.

Both sides of the balance weight portion 10a of the crankshaft 10 in the axial direction are rotatably supported by a pair of ball bearings 8 and 9 provided in the right half 2 and left half 3 of the crankcase 1, respectively. A crank pin 10b provided on the balance weight portion 10a is connected via a connecting rod 11 to a piston (not shown) that slides inside the cylinder block 4. An alternator 12 is attached to the left end of the crankshaft 10, and two oil pumps 13 and 14 are coaxially connected to the right end thereof.

A transmission main shaft 15 functioning as a rear balancer shaft is supported above the rear part of the crankshaft 10 via a pair of ball bearings 16 and 17, and a countershaft 1
8 is supported parallel to the main shaft 15 via a pair of ball bearings 19 and 20. The rotation of the crankshaft 10 is input to the main shaft 15 via a clutch 21 provided at the right end of the main shaft 15, and the rotation of the countershaft 18 is output from a sprocket 22 provided at the left end to the rear wheel via a chain 23. be done. The main shaft 15 and countershaft 18 have
Five gear trains G for selectively establishing multiple gears
1 to G5 are provided.

A front balancer shaft 26 is supported at the front of the crankshaft 10 via a pair of ball bearings 24 and 25 provided in the right half 2 and left half 3 of the crankcase 1, respectively. Right ball bearing 24
An impeller 27a of a cooling water pump 27 is fixed to the right end of the front balancer shaft 26, which is supported by and extends outward from the right half 2 of the crankcase 1, by press fitting. The cooling water pump 27 is covered by a cup-shaped pump cover 5 coupled to the split surface 2b of the right half 2 of the crankcase 1.

Next, the structure of the balancer device provided in the internal combustion engine E will be explained in detail.

1 fixed between the balance weight part 10a of the crankshaft 10 and the left ball bearing 9.
The secondary balancer drive gear 36 meshes with a primary balancer driven gear 29 connected to the front balancer shaft 26 and having the same number of teeth. A semicircular front primary inertia force balancer IF1 is spline-coupled to the left end of the front balancer shaft 26 and rotates at the same speed as the crankshaft 10 in the opposite direction.

2 fixed between the balance weight part 10a of the crankshaft 10 and the right ball bearing 8.
The secondary balancer drive gear 30 meshes with a secondary balancer driven gear 31 supported on the front balancer shaft 26 so as to be relatively rotatable. A semicircular front secondary inertia force balancer IF2 is integrally formed in the secondary balancer driven gear 31, and a front secondary moment balancer is formed in the secondary balancer driven gear 31 by increasing the wall thickness in a semicircular shape. MF2 is formed. By setting the number of teeth of the secondary balancer drive gear 30 to twice the number of teeth of the secondary balancer driven gear 31, the front secondary inertia force balancer IF2 and the front secondary moment balancer MF2 are connected to the crankshaft 10. 2
It rotates in the opposite direction to the crankshaft 10 at twice the speed.

Both primary balancer gears 36, 29 and both secondary balancer gears 30, 31 are arranged symmetrically inside the crankcase 1 on both sides of the balance weight portion 10a of the crankshaft 10 in the axial direction.

A primary driven gear 33 integrally connected to a clutch outer 32 is supported at the right end of the transmission main shaft 15 extending outward from the right half 2 of the crankcase 1 so as to be relatively rotatable. The driven gear 33 is driven by meshing with a primary drive gear 28 keyed to the right end of the crankshaft 10 extending outward from the right half 2 of the crankcase 1 . A rear primary inertial force balancer IR1 is formed in the primary driven gear 33 by increasing its flesh pressure in a semicircular manner. The primary drive gear 28 and the primary driven gear 33 have the same number of teeth, and the rear primary inertia force balancer IR1 rotates at the same speed as the crankshaft 10 in the opposite direction.

The secondary balancer drive gear 30 connected to the crankshaft 10 includes a secondary balancer driven gear 34 supported on the main shaft 15 so as to be relatively rotatable.
The secondary balancer driven gear 34 meshes with a secondary balancer driven gear 35 supported on the countershaft 18 so as to be relatively rotatable. Main shaft 15
The secondary balancer driven gear 34 of the rear secondary moment balancer M is formed by increasing the wall thickness in a semicircular manner.
R2 is formed, and a rear secondary inertial force balancer IR2 is formed in the secondary balancer driven gear 35 of the countershaft 18 by increasing the wall thickness in a semicircular manner. The number of teeth of the secondary balancer drive gear 30 is twice the number of teeth of both the secondary balancer driven gears 34 and 35,
The rear secondary inertia force balancer IR2 and the rear secondary moment balancer MR2 rotate at twice the speed of the crankshaft 10.

In the state shown in FIG. 4 (top dead center state), both the front primary inertial force balancer IF1 and the rear primary inertial force balancer IR1 are in the downward position, and from there they are in the same phase as the crankshaft 10. Rotate counterclockwise at speed.

As is clear from FIG. 1, at top dead center, the pair of secondary inertial force balancers IF2 and IR2 are in the same phase as the pair of primary inertial force balancers IF1 and IR1, and the front secondary moment balancer MF2 is in phase with the pair of primary inertial force balancers IF1 and IR1. is a phase that is 90° ahead of the front secondary inertial force balancer IF2,
The rear secondary moment balancer MR2 has a phase difference of 180° with respect to the front secondary moment balancer MF2. And secondary balancer IF2, IR2, MF
2. MR2 rotates at twice the speed of primary balancers IF1 and IR1.

Next, the operation of the embodiment of the present invention having the above-mentioned configuration will be explained.

As the crankshaft 10 rotates, the front primary inertial force balancer IF1 and the rear primary inertial force balancer IR1 rotate at the same speed as the crankshaft 10,
In addition, as the front secondary inertial force balancer IF2 and the rear secondary inertial force balancer IR2 rotate at twice the speed of the crankshaft 10, the primary component of the inertial force generated by the accelerated movement of the mass of the reciprocating part such as the piston. The second-order components are canceled out, and the vibration of the internal combustion engine E is reduced. Further, since the front secondary moment balancer MF2 and the rear secondary moment balancer MR2 rotate at twice the speed of the crankshaft 10, the secondary component of the moment generated based on the inertia force is canceled out, and the internal combustion engine E vibration is reduced.

Now, the primary balancer gears 36 and 29 that drive the front primary inertia force balancer IF1 provided on the front balancer shaft 26 are connected to the balance weight portion 10a of the crankshaft 10 and the one that supports the crankshaft 10. The secondary balancer gears 30 and 31 are arranged between the ball bearings 9 of the crankshaft and drive the front secondary inertia force balancer IF2 and the front secondary moment balancer MF2 provided on the front balancer shaft 26. 10 balance weight portion 10a and the other ball bearing 8 that supports the crankshaft 10, the primary balancer gears 36, 29 and 2
The thickness of the secondary balancer gears 30, 31 is distributed on both sides of the balance weight portion 10a of the crankshaft 10 in the axial direction. As a result, the lengths of both spans of the crankshaft 10 sandwiching the balance weight portion 10a are made equal, so that the strength of the crankshaft 10 can be improved.

[0024] Also, the primary balancer gears 36, 29
Since the and secondary balancer gears 30 and 31 are all housed inside the crankcase 1, the size of the right side cover 6 that covers the side surface of the crankcase 1 can be reduced in size. That is, as in the conventional case, the primary balancer driven gear 29 is provided at the right end of the front balancer shaft 26, and the primary drive gear 2 is provided at the right end of the crankshaft 10.
8, the primary balancer driven gear 2
9, it becomes necessary to extend the right side cover 7 to the front end of the crankcase 1, resulting in an increase in the size of the right side cover 7. However, in the present invention, since the primary balancer driven gear 29 is disposed on the left side of the front balancer shaft 26, there is no need to cover the primary balancer driven gear 29 with the right side cover 7, and the dimensions of the right side cover 7 can be reduced. Can be made smaller.

Moreover, by directly mounting the cooling water pump 27 on the right end of the front balancer shaft 26 and using the front balancer shaft 26 as the shaft of the cooling water pump 27, the above-mentioned primary balancer driven gear 29 can be directly attached to the right end of the front balancer shaft 26. In combination with the fact that the cooling water pump 27 is disposed on the left side of the balancer shaft 26, the amount of protrusion of the cooling water pump 27 to the right in the axial direction can be reduced, and the width of the front part of the crankcase 1 can be reduced.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various modifications may be made without departing from the scope of the present invention described in the claims. Design changes are possible.

For example, in the embodiment, the two split surfaces 2a and 2b formed on the outside of the right half 2 of the crankcase 1 have a slight step, but by forming them flush, the machining process is easy. Simplification and improvement of processing accuracy can be achieved. It is also possible to integrate the right side cover 6 and the pump cover 5, which are connected to the split surfaces 2a and 2b. Furthermore, the impeller 27a of the cooling water pump 27 can be fastened to the right end of the front balancer shaft 26 with a screw, thereby improving ease of assembly and maintenance.

[0028]

As described above, according to the first feature of the present invention, the primary balancer gear is disposed between the balance weight portion of the crankshaft and one of the bearings supporting the crankshaft, and the secondary balancer gear By disposing the gear between the balance weight portion of the crankshaft and the other bearing, both balancer gears can be rationally housed inside the crankcase. As a result, there is no need to house the balancer gear inside the side cover that covers the side of the crankcase, which not only makes the side cover more compact, but also increases the length of both spans of the crankshaft that sandwich the balance weight part. As a result, the strength of the crankshaft is improved.

According to the second feature of the present invention, since the cooling water pump is directly supported on the balancer shaft, a special cooling water pump shaft is not required, and the number of parts can be reduced. Furthermore, by covering the cooling water pump with the pump cover, there is no need to cover the cooling water pump with the side cover of the crankcase, so the side cover can be further downsized.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an internal combustion engine according to an embodiment of the present invention (cross-sectional view taken along line 1-1 in FIG. 4);

[Figure 2] Enlarged view of the second part of Figure 1

[Figure 3] Enlarged view of the third part of Figure 1

[Figure 4] Cross-sectional view taken along line 4-4 in Figure 1

[Explanation of symbols]

1...Crankcase 5...Pump cover 6...Right side cover (side cover) 7...
... Left side cover (side cover) 8 ... Ball bearing (bearing) 9 ... Ball bearing (bearing) 10 ... Crankshaft 10a ... Balance weight section 26 ... Front balancer shaft (balancer shaft) 27... Cooling water pump 29... Primary balancer driven gear (primary balancer gear) 30... Secondary balancer drive gear (secondary balancer gear) 31... ...Secondary balancer driven gear (secondary balancer gear) 36...Primary balancer drive gear (primary balancer gear) IF1...Front primary inertia force balancer (primary balancer) IF2... Front secondary inertia force balancer (secondary balancer) MF2...Front secondary moment balancer (secondary balancer)

Claims (2)

[Claims] Claim 1: A crankshaft (10) in which both sides of the balance weight part (10a) in the axial direction are supported by a pair of bearings (8, 9) in the crankcase (1), and a crankshaft parallel to the crankshaft (10). Case (1)
A balancer shaft (26) supported on the balancer shaft (26), and a primary balancer (IF) supported on this balancer shaft (26).
1) and a secondary balancer (IF2, MF2), and a crankshaft (10) to the primary balancer (IF1).
primary balancer gears (36, 29) that transmit the rotation of the crankshaft (10) to the secondary balancer (IF2, MF2), and secondary balancer gears (36, 29) that transmit the rotation of the crankshaft (10) to the secondary balancer (IF2, MF2).
30, 31) and side covers (6, 7) that cover the sides of the crankcase (1), the primary balancer gear (36, 2
9) is arranged between the balance weight part (10a) of the crankshaft (10) and the one bearing (9),
A balancer device for an internal combustion engine, characterized in that a secondary balancer gear (30, 31) is disposed between a balance weight portion (10a) of a crankshaft (10) and the other bearing (8). 2. A cooling water pump (27) is provided at the shaft end of the balancer shaft (26) that protrudes from the crankcase (1), and the cooling water pump (27) is installed outside the crankcase (1). Balancer device for an internal combustion engine according to claim 1, characterized in that it is covered with a pump cover (5) mounted on the side.