JP2003090225A - Housing for balancing shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide housings for balancing shafts, offering construction assuring high rigidity while avoiding interference with the larger end of a connecting rod. SOLUTION: The housings 14U, 14L for the balancing shafts, arranged adjacent to a crank shaft 1 for housing two balancing shafts 13L, 13R to be mutually reverse rotated for cancelling force of vibration generated by a piston of an engine, comprise openings 42F, 42R provided corresponding to the track of the large end 41 of the connecting rod and protrusions 43, 44 provided along at least portions of the peripheral edges of the openings. Thus, the openings provided for avoiding the interference with the large end of the connecting rod give no lower rigidity to the housings.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a housing for accommodating a balance shaft provided with a counterweight for canceling a vibration force generated by an engine piston.

[0002]

2. Description of the Related Art A balance shaft equipped with a counterweight for canceling a secondary vibration force generated by an engine piston is disposed below a crankshaft in an oil pan so that a chain / sprocket mechanism, a gear mechanism, etc. A balancing device for transmitting the rotation of the crankshaft to the balance shaft via the known device is known, for example, from Japanese Utility Model Publication No. 5-39233.

Since the balance shaft of the above-mentioned balancer is provided below the oil level in the oil pan, the whole balance shaft is a housing in order to prevent inconvenience caused by stirring the lubricating oil by the balance shaft. Is covered.

By the way, in order to promote compactness of the engine, it is preferable that the balancing device is arranged as close to the crankshaft as possible.

[0005]

However, in order to dispose the balancer close to the crankshaft, it is necessary to cut off a part of the housing in order to avoid interference with the large end of the connecting rod. Cutting the housing lowers the rigidity of the housing.

The present invention has been devised to solve the above-mentioned problems of the prior art, and its main purpose is to ensure high rigidity while avoiding interference with the large end of the connecting rod. To provide a balance shaft housing configured to obtain.

[0007]

In order to achieve such an object, according to claim 1 of the present invention, two balance shafts (in opposite directions) for canceling the vibration force generated by the piston of the engine ( 13L / 13R), the structure of the balance shaft housing (14U / 14L) arranged adjacent to the crankshaft (1) is changed to a portion corresponding to the locus of the large end portion (41) of the connecting rod. It is characterized in that it has an opening (42F / 42R) provided and a protrusion (43/44) protruding upward along at least a part of the peripheral edge of the opening. By doing so, the rigidity of the periphery of the opening provided in order to avoid interference with the connecting rod is increased by the protrusion protruding upward along at least a part of the peripheral edge of the opening. This reduces the rigidity of the housing.

Further, in the present invention, a fastening portion (fastening boss 40) provided on the outer peripheral portion for the engine body.
And an opening provided in a portion corresponding to the locus of the large end portion of the connecting rod, and the opening is higher in the outer portion (47) than in the central portion (46). It is characterized by that. In this way, the rigidity of the housing due to the opening provided to avoid the interference with the connecting rod is compensated by the outer portion located around the fastening portion with respect to the engine body which is essentially rigid.

According to a third aspect of the present invention, there is provided an opening provided in a portion corresponding to a locus of the large end portion of the connecting rod,
Characterized by having an opening (48) provided in a portion corresponding to a gear for interlocking and connecting the balance shafts of the book, and a rib (49) connecting these openings to each other. And With this configuration, the rib connecting the openings compensates for the decrease in the rigidity of the housing due to the openings provided to avoid the interference with the connecting rod.

According to another aspect of the present invention, there is provided an opening provided at a position adjacent to the bearing wall (26a) supporting the balance shaft and corresponding to the locus of the large end of the connecting rod, and the balance shaft. An extension wall (50) extending from the bearing wall toward the opening so as to cover at least a part thereof.
F.50R).
In this way, the rigidity of the bearing wall is increased by the extension wall extending from the bearing wall toward the opening, so that the decrease in the rigidity of the housing due to the opening provided to avoid the interference with the connecting rod is compensated. Be seen.

Further, according to a fifth aspect of the present invention, an opening provided at a position adjacent to a bearing wall supporting the balance shaft and corresponding to a locus of a large end portion of the connecting rod, the bearing wall and the opening. And an extending wall (51) extending in a direction orthogonal to the axis of the balance shaft. By doing so, the rigidity of the bearing wall is increased by the extending wall along the bearing wall,
The decrease in the rigidity of the housing due to the opening provided to avoid the interference with the connecting rod is compensated.

[0012]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a reciprocating piston engine to which the present invention is applied. The engine E is an in-line four-cylinder engine in which a crankshaft 1 extends in the horizontal direction and includes a head cover 2, a cylinder head 3, a cylinder block 4, a lower block 5, a balancing device 6, and an oil pan 7. .

The balancing device 6 is intended to reduce the secondary vibration of the engine E caused by the reciprocating motion of the piston, and is contained in the oil pan 7 to lower the lower block 5 (crank shaft). 1) (below 1). The balancing device 6 includes a large sprocket 8 fixed to a front end portion of the crankshaft 1 (hereinafter, the crank pulley or the chain case side is referred to as a front side), and a left side (hereinafter, the left-right direction faces the crank pulley or the chain case). The small sprocket 9 fixed to the front end of the balance shaft (described in detail later) and the endless link chain 10 hung between the large and small sprocket 8
The rotation of the crankshaft 1 is transmitted via the and.

The endless link chain 10 is steady by a chain guide 11 fixed to the left side of the center of the crankshaft on the front surface of the lower block 5, and is located on the right side of the small sprocket 9 on the front end surface of the balancing device 6. The fixed chain tensioner 12 ensures that proper tension is always applied.

As shown in FIGS. 2 and 3, the balancing device 6 includes a pair of left and right balance shafts 1 having substantially the same shape.
3L / 13R and these two balance shafts 13L / 13
In order to support and accommodate R in parallel with each other, an upper housing 14U and a lower housing 1 which are vertically divided into two along a plane passing through the centers of both balance shafts 13L and 13R.
It is equipped with 4L.

Both balance shafts 13L and 13R are helical gears 15 integrally connected to the respective balance shafts 13L and 13R.
L and 15R are interlockingly connected to each other. Here, as described above, the driving force of the crankshaft 1 is transmitted to the left balance shaft 13L via the large sprocket 8, the endless link chain 10, and the small sprocket 9. As a result, the left balance shaft 13L is driven to rotate in the same direction as the crankshaft 1 at a rotation speed twice that of the crankshaft 1, and the right balance shaft 13R rotates in the opposite direction due to the meshing of the helical gears 15L and 15R. Driven.

In the portion of the upper housing 14U corresponding to the helical gears 15L and 15R, the respective helical gears 15L and 1 which are integrated with the respective balance shafts 13L and 13R.
A thrust receiving surface 16 is formed so as to contact both end surfaces of the 5R in the axial direction. Further, this portion is opened upward, and a part of the tooth surface of both helical gears 15L and 15R is exposed in the oil pan, so that the lubricating oil dripping from above or splashing in the oil pan 7 Both helical gears 1
The 5L and 15R meshing portions and the thrust receiving surface 16 enter into the meshing portion, and the same portion is sufficiently lubricated.

Each of the balance shafts 13L and 13R is integrally formed with a relatively small diameter first journal portion 17 at its front end side and a relatively large diameter second journal portion 18 at its rear end side. In addition, each balance shaft 13L and 13R
On the rear end side, a counterweight 19 which is divided into two parts is formed integrally before and after the second journal portion 18. The counterweight 19 has its center of gravity deviated radially outward from the center of rotation.

On the other hand, the first of the balance shafts 13L and 13R
The journal portion 17 includes the first bearing hole 2 provided in the first bearing wall 25a that is integral with the front end portion of the lower housing 14L.
Supported by 5. The second journal portion 18 of each balance shaft is supported in the second bearing hole 26 provided with a halved metal bearing formed by joining the upper and lower housings 14U and 14L to each other.

When the balance shafts 13L and 13R are housed in the housings 14U and 14L, the front ends of the balance shafts 13L and 13R are inserted into the first bearing holes 25 and the first journal portions 17 are inserted. The balance shafts 13L and 13R are supported by the first bearing holes 25, and the balance shafts 13L and 13R
The journals 18 are respectively placed, and in this state, the half of the second bearing hole 26 on the upper housing 14U side is aligned with the second journals 18 of the balance shafts 13L and 13R. Housing 14U ・ 14
If L is joined to each other, both balance shafts 13L and 13R
Will be rotatably accommodated in both housings 14U and 14L.

Upper and lower housings 14U and 14L
As shown in FIG. 3, a trochoid type lubricating oil pump 27 for pumping lubricating oil to each part of the engine is provided on the front end face of the. The lubricating oil pump 27 comprises an outer rotor 29 received in a pump housing 28 bolted to the front end faces of both housings 14U and 14L, and an inner rotor 30 connected to the front end of the right balance shaft 13R. Then, the inner rotor 30 which rotates integrally with the right balance shaft 13R cooperates with the outer rotor 29, and sucks from an oil strainer 31 attached to the bottom wall of the lower housing 14L through an intake pipe 32 integrally formed in the bottom wall of the lower housing 14L. The lubricating oil in the oil pan 7 is pumped to each part of the engine through an oil passage (not shown) provided in the lower block 5 and the cylinder block 4.

Both upper and lower housings 14U
14L is the left and right sides in the portion between the helical gears 15L and 15R and the front counterweight 19, and the second
The second bearing wall 26a, which is fastened to each other with a total of five bolts B1 and B2 at a position with the second bearing wall 26a that supports the journal portion 18, acts particularly on the radial acceleration due to the rotation of the counterweight 19. It is designed so that loosening does not easily occur in the part.

The balancing device 6 constructed as described above is
Left and right sides of the second bearing wall 26a and the pump housing 2
8 are fastened to the lower surface of the lower block 5 by through bolts B3 that are inserted from below into bolt holes H formed in boss portions 40 integrally formed on both sides of the lower block 5.

As shown in FIGS. 4 and 5, the two balance shafts 13 on the upper wall of the upper housing 14U.
Openings 42F and 42R for avoiding interference with the rotation locus of the large end portion 41 of the connecting rod are formed in portions of the L and 13R corresponding to the four counterweights 19, respectively. Since the rigidity of the upper housing 14U is reduced by providing these four openings 42F and 42R, the reinforcing measures listed below are taken.

Upward protrusions 43 and 44 are formed along the front and outer edges of the two openings 42F located on the front side of the second bearing wall 26a. Further, an upward protruding portion 45 is formed along the rear edges of the two openings 42R on the rear side of the second bearing wall 26a. These protrusions 43, 44, 45
Is provided, the rigidity around the openings 42F and 42R is enhanced.

The outside portion 47 is higher than the central portion 46 between the openings 42F and 42R arranged side by side, that is, the portion between the two balance shafts. In this way, the rigidity around the openings 42F and 42R is enhanced by making the outer portion 47 located around the fastening portion for the engine body, which has essentially high rigidity, higher than the central portion 46.

The balance shaft 13L. And the balance shaft 13L.
It is connected by a rib 49 extending along the axis of 13R. As a result, it is possible to prevent the rigidity of the upper housing 14U from being lowered due to the provision of the openings 42F and 42R.

Eave-shaped extending walls 50F and 50R having an arcuate contour that is convex upward are provided on both front and rear surfaces of the second bearing wall 26a so as to cover a part of each counterweight 19. The free end edge of the extension wall 50F on the front side of the second bearing wall 26a forms the rear edge of the opening 42F on the front side, and
a, the free end edge of the extension wall 50R on the rear side is the rear side opening 42R.
Forms the leading edge of. By extending the eave-shaped extending walls 50F and 50R from both the front and rear surfaces of the second bearing wall 26a in this manner, the rigidity of the second bearing wall 26a is enhanced, and the openings 42F and 42R are provided with this. It is intended to compensate for the decrease in rigidity of the upper housing 14U.

The balance shafts 13L and 13 are provided on both the front and rear sides to avoid the fastening bolt B2 on the upper end surface of the second bearing wall 26a.
An extended wall 51 is formed in a direction orthogonal to the R axis.
By providing the extended wall 51 along the second bearing wall 26a in this way, the rigidity of the second bearing wall 26a is increased, and therefore the fastening rigidity of the upper and lower housings 14U, 14L can be significantly increased. Moreover, since the extending wall 51 and the extending walls 50F and 50R are connected to each other, the rigidity around the openings 42F and 42R can be significantly improved.

[0031]

As described in detail above, according to the present invention, a great effect can be obtained in enhancing the rigidity of the balance shaft housing provided with an opening for avoiding interference with the large end of the connecting rod.

[Brief description of drawings]

FIG. 1 is a front view showing a main part of an engine to which the present invention is applied by cutting out only a main part thereof.

FIG. 2 is a partial vertical cross-sectional view showing the inside of the oil pan cut along the axis of the left balance shaft.

FIG. 3 is a vertical cross-sectional view cut along the axis of the right balance shaft of the balancing device.

FIG. 4 is a top view of the balancing device.

FIG. 5 is a perspective view of an upper housing.

[Explanation of symbols]

1 crankshaft 13L / 13R Balance axis 14U ・ 14L housing 26a Bearing wall 40 fastening boss 41 Large end of connecting rod 42F / 42R opening 43/44 Projection 46 Central part 47 outer part 48 openings 49 ribs 50F / 50R extension wall 51 Extended wall

Claims (5)

[Claims] 1. A balance shaft housing disposed at a position adjacent to a crank shaft for accommodating two balance shafts rotating in opposite directions for canceling a vibration force generated by a piston of an engine, The housing has an opening provided in a portion corresponding to the locus of the large end portion of the connecting rod, and a protrusion protruding upward along at least a part of a peripheral edge of the opening. A housing for the balance shaft. 2. A balance shaft housing arranged at a position adjacent to a crank shaft for accommodating two counter shafts rotating in opposite directions for canceling a vibration force generated by an engine piston. The housing has a fastening portion for the engine body provided on the outer peripheral portion thereof, and an opening provided at a portion corresponding to the locus of the large end portion of the connecting rod, and the opening is closer to the center side portion. Also, the housing for the balance shaft is characterized in that the outer part is made higher. 3. A balance shaft housing arranged at a position adjacent to a crank shaft for accommodating two balance shafts rotating in opposite directions for canceling a vibration force generated by an engine piston. The housing is provided with an opening provided in a portion corresponding to the locus of the large end of the connecting rod, an opening provided in a portion corresponding to a gear for interlockingly connecting the two balance shafts, and these openings. A balance shaft housing having a rib connecting between the two. 4. A balance shaft housing arranged at a position adjacent to a crank shaft to accommodate two balance shafts that rotate in opposite directions to cancel a vibration force generated by an engine piston, An opening provided at a position adjacent to the bearing wall supporting the balance shaft and corresponding to a locus of the large end of the connecting rod; and from the bearing wall to the opening so as to cover at least a part of the balance shaft. A balance shaft housing having an extension wall extended toward the front. 5. A balance shaft housing arranged at a position adjacent to a crank shaft for accommodating two balance shafts rotating in opposite directions for canceling a vibration force generated by an engine piston, An opening provided at a position adjacent to the bearing wall supporting the balance shaft and corresponding to the locus of the large end of the connecting rod, and orthogonal to the axis of the balance shaft between the bearing wall and the opening. A balance shaft housing having an extending wall extending in the direction of.