JP2003322214A - Balancer for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a balancer for an engine wherein labor is saved on in machining to reduce construction cost, and yield of material is improved to reduce cost on material for totally realizing cost reduction of products. <P>SOLUTION: This balancer 30 is provided with balancer weights 21 and 25 as separate bodies to balancer shafts 11 and 12, and the balancer shafts are fit into shaft insertion holes 31 in the balancer weights. The balancer weight is molded by press punching into a sector form having an opening angle of about 90 deg. between both side edge parts that are symmetric except for a circular part. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is provided for various engines such as motorcycles and four-wheeled vehicles and small outboard motors.
The present invention relates to an engine balancer suitable for removing vibrations generated by reciprocating motion of a piston or the like when the engine is driven.

[0002]

2. Description of the Related Art Generally, in a vehicle engine, for example, a primary vibration is generated due to an inertial force generated by a reciprocating motion of a piston or the like at the time of driving, which is one of the causes for vibrating the vehicle body. Therefore, conventionally, the engine is usually provided with a balancer in order to remove the primary vibration.

Conventionally, this type of engine balancer has a balancer shaft 1 as shown by reference numeral 1 in FIG. 6, for example.
In contrast to a, the balancer gear 1b and the balancer weight 1c are integrally formed by machining such as cutting (see JP-A-11-325184). Then, the balancer weight 1c is formed in a semicircular shape as shown in FIG. 7 according to the total mass of pistons, connecting rods, etc. (not shown), and the balancer gear 1b having this balancer weight 1c is meshed with the crank gear.

Therefore, when the engine is driven, when the piston reciprocates, the reciprocating stroke is transmitted through the connecting rod to rotate the crank, and the rotation is transmitted from the crank gear to the balancer gear 1b. When the balancer gear 1b is rotated, the balancer gear 1 rotates integrally with the balancer weight 1c, and the rotation of the balancer weight 1c absorbs and removes vibration.

[0005]

However, the conventional engine balancer has a structure in which the semicircular balancer weight 1c is integrally formed with the balancer shaft 1a, and machining such as cutting is performed for that purpose, and therefore only that is required. There is a problem that it takes time and labor for processing, the construction cost is high, the yield is low with respect to the material, and the material cost is correspondingly high, and as a result, the overall product cost is significantly high.

[0006]

Therefore, in order to solve the above-mentioned conventional problems, the invention according to claim 1 is, for example, as shown in the embodiments described below with reference to the drawings. The balancer weights 21 and 25 are separately provided for the shaft such as 12, and the shaft insertion hole 31 is provided in the balancer weights 21 and 25.
A balancer 30 for an engine configured by press-fitting the shaft into the balancer weights 21 and 25,
The symmetrical side edges e except for the circumferential portion s are characterized by being formed by press punching into a fan shape having an opening angle of approximately 90 degrees.

According to the invention described in claim 2, the invention described in claim 2 is, for example, as shown in the embodiments described below with reference to the drawings, in which a balancer is used for a balancer shaft 11 or 12. A balancer 30 is provided with the weights 21 and 25 separately, and the shafts are press-fitted into the shaft insertion holes 31 of the balancer weights 21 and 25. The balancer weights 21 and 25 are formed by press punching. While being molded, a plurality of vertical grooves 35 ... Which absorb the interference between the shaft and the shaft insertion hole 31 at the time of press fitting are provided on the inner peripheral surface 31a of the shaft insertion hole 31. .

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 show a part of a four-cycle single cylinder engine for a motorcycle equipped with a balancer according to the present invention. In this engine E, balancer shafts 11 and 12 are arranged on both left and right sides of a crankshaft 10 in the center of the drawing, a camshaft 13 is arranged adjacent to one balancer shaft 11, and both ends of these shafts 10 to 13 are holders. It is rotatably supported between 14 shafts.

The crankshaft 10 is divided into two parts in the axial direction, is integrally connected by a crank pin, and a crank gear 15 is attached to the lower end portion in the drawing. Then, the large end portion 16a of the connecting rod 16 is attached to the crank pin.
While rotatably connecting the small end 16b on the opposite side,
It is connected to a piston 18 via a piston pin 17. Therefore, when the piston 18 reciprocates in the cylinder, this reciprocating stroke is transmitted to the crankshaft 10 via the connecting rod 16 to rotate the crank gear 15.

The cam shaft 13 includes a pair of cams 19a
19b are assembled with their phases being shifted by approximately 90 degrees from each other, and a cam driven gear 20 is assembled at the lower end in the figure.

On the other hand, the balancer shaft 11 has a balancer weight 21 assembled substantially in the middle in the axial direction, a large-diameter balancer gear 22 assembled on the lower end side in the drawing to engage with the crank gear 15, and a small-diameter cam drive gear 23.
Is assembled and meshed with the cam driven gear 20, and the rotational force of the crankshaft 10 is transmitted to the camshaft 13. Then, the cams 19a and 19b are respectively rotated according to the rotation of the cam shaft 13 to control the opening and closing of exhaust valves and intake valves (not shown).

The balancer shaft 12 is assembled with a balancer weight 25 substantially in the middle in the axial direction, a balancer gear 26 is assembled at the lower end of the figure, and meshes with the crank gear 15, so that the rotational force of the crankshaft 10 is transmitted to the balancer shaft 12. It is supposed to be done. In this way, the pair of balancer shafts 11 and 12, the balancer gears 22 and 26 and the balancer weights 21 and 25, respectively, described above.
This constitutes the balancer 30 of the present invention.

Therefore, in the above-described engine E, when the piston 18 reciprocates during driving, the reciprocating stroke is transmitted through the connecting rod 16 to rotate the crankshaft 10, and the rotation is mediated by the crank gear 15. The balancer gears 22 and 26 are transmitted to rotate the balancer gears 22 and 26. When the balancer gears 22 and 26 rotate, they are integrated with the balancer shafts 11 and 12.
And the balancer weights 21 and 25 rotate, and the rotation of the balancer weights 21 and 25 absorbs and removes the primary vibration generated based on the reciprocating motion of the piston 18.

By the way, the balancer 30 according to the present invention is
The balancer weights 21 and 25 are provided separately from the balancer shaft, and the balancer weights 21 and 25 are formed into a fan shape with a shaft insertion hole 31 by punching. Specifically, as shown in FIG. 3, after punching with a press, the symmetrical side edges e except for the circumferential portion s have an opening angle of about 90 degrees from the coiled metal workpiece (blank) B. The eggplant-shaped balancer weights 21 and 25 are manufactured. Since the weight shape is a fan shape with an opening angle of about 90 degrees, the blank shape is densely laid out for the blank B by processing the blank B by alternately changing the direction by 180 degrees in the length direction. Can be set. Even if the weight shape is changed to a semicircular shape as in the conventional case, the amount of the material of the end portion d shown by the chain line in FIG. 3 is not wasted and the yield is improved.

Further, in the balancer 30 of the present invention, when the balancer weights 21 and 25 are formed by punching, the inner peripheral surface 31a of the shaft insertion hole 31 is provided with a plurality of vertical grooves 35 ... As shown in FIG. The feature is that it is formed in the vertical direction. In the illustrated example, the vertical grooves 35 have a substantially V-shaped cross section, and are formed at equal intervals in four directions on the inner peripheral surface 31 a of the shaft insertion hole 31. Then, the balancer weights 21 and 25 are mounted on the balancer shaft 11
2 is press-fitted into the shaft insertion hole 31 and assembled.

Since the balancer 30 of the present invention has a structure in which the vertical grooves 35 are formed in the balancer weights 21 and 25,
When the balancer shafts 11 and 12 are press-fitted, even if the interference between the balancer shafts 11 and 12 and the shaft insertion hole 31 is excessively large, the excessive amount of the interference is absorbed by the vertical grooves 35. . Therefore, the balancer 30
Then, the above-mentioned tightening margin can be set in advance by a predetermined amount depending on the vertical grooves 35.

As a result, as shown in FIG. 5, the relationship between the press-fitting load (slip torque) of the balancer shaft and the tightening allowance at the time of shaft press-fitting is shown in FIG. In the present invention, it can be seen that in the present invention, the vertical groove 35 absorbs the tightening margin by the same excessive amount, and a predetermined sufficient tightening margin, that is, an effective slip torque can be secured. According to the experiment, the slip torque is increased by 10% or more in average value as compared with the normal case without the vertical groove. Thereby, in the present invention, according to the vertical groove 35 ...
Since the tightening margin can be set excessively by a predetermined amount in advance, the control width of such tightening margin can be made larger than that in the usual case.

In the illustrated embodiment described above, the vertical grooves 35 having a substantially V-shaped cross section are formed at equal intervals on the four sides of the inner peripheral surface 31a of the shaft insertion hole 31. However, in the present invention, as long as the effect of absorbing the interference can be obtained, the flute shape can be formed to have an arc cross section, a U shape, or the like, and the number of flutes installed, the arrangement interval, etc. are also shown in the illustrated example. Is not limited.

In the illustrated embodiment described above, the balancer weights 21 and 25 are replaced with the balancer shafts 11 and 1.
Although the example in which it is provided as a separate body from 2 is shown, the present invention can also be provided by being provided on another appropriate shaft such as a crankshaft / camshaft.

Although the examples of the balancer used in the motorcycle engine have been described above, it goes without saying that the balancer according to the present invention can be widely applied to various other engines.

[0022]

According to the present invention configured as described above, the following effects can be obtained.

According to the invention described in claims 1 and 2,
Since the balancer weight is separate from the shaft, and the balancer weight is formed by press punching and press-fitting the shaft, it is possible to simplify the construction by omitting the work involved in conventional machining. Together with
There is no need for extra construction cost due to machining, and it is possible to reduce construction cost and product cost by that amount.

Moreover, according to the invention of claim 1,
Since the weight shape is a fan shape with an opening angle of about 90 degrees,
By changing the orientation of the blank in the length direction during pressing, it is possible to set the punched shape layout to the blank more densely, and as a result,
The material yield is improved, and the material cost can be reduced accordingly.

In addition, according to the invention of claim 2,
Since the shaft insertion hole has a plurality of vertical grooves on the inner peripheral surface, when the shaft is press-fitted, even if the tightening margin between the shaft and the shaft insertion hole is too large, the tightening margin is too large. Minutes can be absorbed by the vertical groove, and as a result, it is possible to secure a predetermined sufficient tightening margin, that is, an effective slip torque, in the conventional case where the yield region is reached. It is possible to improve the sex. Therefore, in the present invention, according to the vertical groove,
Since the tightening margin can be set in advance by a predetermined amount excessively, and the control margin of the tightening margin can be increased correspondingly, the production efficiency of the balancer can be further improved.

[Brief description of drawings]

FIG. 1 is a motorcycle equipped with the balancer of the present invention;
It is a top view which shows a part of cycle single cylinder engine.

FIG. 2 is a vertical cross-sectional view of the engine portion of FIG.

FIG. 3 is a configuration diagram illustrating a layout of a weight punching shape for a blank.

FIG. 4 is a partial lateral cross-sectional view showing an enlarged shape of a shaft insertion hole.

FIG. 5 is a graph showing the relationship between the press-fitting load (slip torque) of the balancer shaft and the tightening allowance when the shaft is press-fitted.

FIG. 6 is a plan view showing a structure of a conventional balancer.

7 is a cross-sectional view taken along a line showing a cross-sectional position in FIG.

[Explanation of symbols]

10 crankshaft 11 ・ 12 Balancer shaft 18 pistons 21.25 Balancer weight 22.26 Balancer gear 30 Balancer 31 Shaft insertion hole 31a Inner peripheral surface of shaft insertion hole 35 vertical groove E engine e Balancer weight circumference s Side edge of balancer weight

Continued front page    (72) Inventor Akio Kobayashi             2-5-10 Nishibokima, Adachi-ku, Tokyo             Ceremony company Hirata Tokyo Works (72) Inventor Shohei Hayakawa             4-37-8 Misugidai, Hanno City, Saitama Prefecture

Claims (2)

[Claims] 1. A balancer for an engine, which comprises a balancer weight separately from a shaft, and the shaft is press-fitted into a shaft insertion hole of the balancer weight, wherein the balancer weight has a circumferential portion. A balancer for an engine, characterized by being formed by press-punching into a fan shape whose both side edges which are symmetric to each other have an opening angle of approximately 90 degrees. 2. A balancer for an engine, comprising a balancer weight separately from the shaft, and the shaft being press-fitted into a shaft insertion hole of the balancer weight, wherein the balancer weight is formed by press punching. On the other hand, the engine balancer is characterized in that a plurality of vertical grooves that absorb the interference between the shaft and the shaft insertion hole at the time of press fitting are provided on the inner peripheral surface of the shaft insertion hole.