JP3360678B2 - Balancer device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a balancer device that is driven in synchronization with a crankshaft so as to suppress rotational vibration of an internal combustion engine.

[0002]

2. Description of the Related Art In order to suppress the rotational vibration of an internal combustion engine,
2. Description of the Related Art There is conventionally known a balancer device in which a pair of balancer shafts having eccentric weights having a semicircular cross section are provided in parallel with a crankshaft, and the balancer shaft is rotated synchronously with the crankshaft.

For example, Japanese Utility Model Laid-Open Publication No. 1-83946 and Japanese Utility Model Laid-Open Publication No. Sho 62-28937 disclose a case in which a housing is attached to a lower part of a cylinder block in a crankcase of an internal combustion engine, and a pair of balancer shafts are rotatable in the housing. 1 shows a balancer device configured to be accommodated in the balancer.

In this balancer device, the balancer shaft is generally driven by a crankshaft via, for example, a chain, a timing belt, or a gear mechanism. 19
No. 0942 (Japanese Patent Application Laid-Open No. 6-33989), a gear is provided on each balancer shaft, meshes with each other in the housing, and the rotation of the crankshaft is connected to one of the balancer shafts via a chain or the like. A configuration for transmitting the signal has been considered.

That is, in this configuration, the rotation of the crankshaft is first transmitted to one of the balancer shafts, and the other balancer shaft is driven in the opposite direction via gears in the housing that mesh with each other.

[0006]

However, if the gears meshing with each other are accommodated in the housing as described above, a lubrication mechanism for the gears is required.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a balancer device for an internal combustion engine that can appropriately lubricate gears in a housing without complicating the configuration.

[0008]

SUMMARY OF THE INVENTION Accordingly, the present invention has a housing mounted below a cylinder block in a crankcase of an internal combustion engine, an eccentric weight portion, and is rotatably housed in the housing. And a pair of balancer shafts arranged in parallel with each other. In a balancer device for an internal combustion engine in which both balancer shafts rotate in opposite directions to each other, a concave portion formed between two projecting portions is provided on an upper surface of the housing, and a lower portion of the concave portion is directed toward a gear inside the housing. The communication hole is formed so as to penetrate therethrough.

Further, in the invention according to claim 2, the housing has a gear accommodating portion for accommodating the gear below the concave portion, and the communication hole has a bottom portion of the concave portion and an upper portion of the gear accommodating portion. Is in communication.

In the crankcase in which the housing is arranged, a large amount of lubricating oil droplets are constantly scattered as the crankshaft rotates. Further, the lubricating oil returning from the cylinder head side or the lubricating oil supplied to the cylinder drops from the upper wall surface of the crankcase. These oil droplets accumulate in recesses formed on the upper surface of the housing, and are supplied from here to gears in the housing through communication holes.

[0011] In particular, according to the structure of the second aspect, a communication hole is provided in an upper portion of the gear accommodating portion, and lubricating oil is dropped on the gear from above.

[0012]

[0013]

Effects of the Invention According to the present invention, can be lubricated accurately housing internal gear without forming a complex lubricating oil passage, a large complicated and housing structure of a case where the forced lubrication mechanism This makes it possible to avoid such a problem as the conversion.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 2 shows a cross section of a main part of an internal combustion engine provided with the balancer device 1 according to the present invention. An upper 5 is attached, and an oil pan lower 7 is attached to a flange 6 at a lower edge thereof. The cylinder block 2 has a deep skirt shape, and a crankshaft 10 is supported on a bulkhead 8 thereof through a bearing cap 9.

The balancer device 1 is housed in a crankcase 11 constituted by the oil pan upper 5 and the oil pan lower 7, and has a cylinder block 2
Mounted at the bottom. The housing 12 constituting the balancer device 1 is formed into a housing upper 13 and a housing lower 14 so as to be divided into two parts. The housing 12 accommodates a pair of balancer shafts 15 and is integrally formed by a plurality of bolts 16. Are combined. The housing upper 13 has four legs 17 and bolts 18 penetrating the legs 17 and the housing lower 14.
Thereby, the entire housing 12 is fixed to the bulkhead 8 of the cylinder block 2. One of the balancer shafts 15 is interlocked with the crankshaft 10 via a chain 19, and the balancer shafts 15 are connected to a gear 20 inside the housing 12.
(See FIG. 4) so as to rotate in opposite directions to each other. Specifically, the crankshaft 10 rotates in the direction of the arrow ω, and accordingly, the pair of balancer shafts 15 rotate as shown by the arrows ω ₁ and ω ₂ , respectively. still,
The dashed line W in FIG. 2 indicates the rotation locus of the counterweight.

FIGS. 3 and 4 show details of the balancer device 1, in which the balancer shaft 15 is shown by imaginary lines. Each of the housing upper 13 and the housing lower 14 is cast from an aluminum alloy, and has a substantially symmetrical shape with respect to the dividing surface as shown in FIG. Are formed in parallel. Each shaft accommodating chamber 21 is partitioned back and forth by a substantially central first bearing portion 22. That is, it is partitioned into the first weight accommodation section 23 at the front and the second weight accommodation section 24 at the rear. Further, between the gear housing 25 located at the front end of the housing 12 and the first weight housing 23, the second
A bearing 26 is provided. The first and second bearing portions 2
Lubricating oil is supplied to the cylinder blocks 2 and 26 from the cylinder block 2 side via an oil hole 27 and an oil groove 28.

The balancer shaft 15 has a shaft portion rotatably supported by the first and second bearing portions 22 and 26 and a portion corresponding to the first and second weight accommodating portions 23 and 24. Weight portion 2 having a semicircular cross section (see FIG. 1)
9 are formed. A gear 20 meshing with each other is attached to the front end, and this gear 20 is housed in a gear housing 25. The front end of one balancer shaft 15 penetrates the housing 12 and protrudes, and a sprocket 31 that meshes with the chain 19 is mounted here.

As shown in FIG. 3, a plurality of protrusions 41 to 44 are provided on the upper surface of the housing upper 13. The protrusion 42 located above the gear housing 25 and the protrusion 41 located at the forefront end of the housing 12.
And a concave portion 45 opening upward is formed between the first and second portions, and a portion corresponding to the bottom wall of the concave portion 45 is provided with:
The communication hole 46 is formed through. This communication hole 46 is
The communication hole 46 opens at a position above the gear 20, and the bottom of the recess 45 communicates with the top of the gear housing 25 through the communication hole 46.

The left and right shaft housing chambers 21 are formed independently as shown in FIG. The first and second weight receiving portions 22 and 23, which are the main portions of each shaft receiving chamber 21, are formed in a substantially cylindrical shape as shown in FIG. Is
It is not a perfect circle but a shape that approximates an involute curve. Specifically, a gap 32 generated between the outer peripheral surface of the weight portion 29 and the lower portion 32a of the housing 12 is the narrowest, and the balancer shaft 1
5 so that the inner peripheral surface 23 gradually increases along the rotation direction
a and 24a are formed. In the lower part of the housing 12 where the gap 32 is largest, an oil discharge port 33 is formed so as to open in the tangential direction. That is, with the oil discharge port 33 interposed,
The portion 32a having the smallest gap 32 and the portion 32 having the largest gap
b are adjacent to each other, and an oil discharge port 33 is opened at a portion serving as a step.

3 and 4, when viewed in the axial direction of the balancer shaft 15, the oil outlet 33 is provided only at the front and rear ends of the first and second weight accommodating portions 23 and 24. Is provided. That is, the first and second
An oil discharge port 3 is provided in a portion adjacent to the bearing portions 22 and 26.
3 is open. And each weight accommodation part 23,2
The inner peripheral surfaces 23a and 24a of 4 are not completely cylindrical surfaces in the axial direction, but have a shape that is slightly thinner at the center and larger in diameter at both ends. In other words, the oil outlet 33 has a gentle tapered surface from the central portion in the axial direction. Accordingly, a step 34 in the rotational direction is formed at the center of each of the weight storage sections 23 and 24 having no oil discharge port 33 in a shape bent in a mountain shape as shown in FIG. An opening for machining is provided on the rear end surface of the housing 12, and is finally closed by a plug 35 made of synthetic resin or the like.

In the above configuration, the first and second oil holes 27
The lubricating oil supplied to the second bearing portions 22 and 26 flows out to the first and second weight accommodating portions 23 and 24 after lubrication, and is discharged to the outside of the housing 12 through the oil discharge port 33. Here, the weight portion 29 rotates at a high speed in each of the weight accommodating portions 23 and 24, but the inner peripheral surfaces 23a and 2
The lubricating oil flows smoothly in the rotational direction and is efficiently discharged from the oil discharge port 33 because the 4a is gradually positioned to the outer peripheral side in the rotational direction. In particular, since the oil discharge port 33 is adjacent to the bearing portions 22 and 26, the lubricating oil flowing out of the bearing portions 22 and 26 is immediately discharged. In addition, the lubricating oil that has received the centrifugal force is directed toward the front and rear ends where the weights of the weight accommodating portions 23 and 24 are relatively large, and is reliably guided to the oil discharge port 33.

The oil level in the crankcase 11 is lower than the housing 12 when the engine is operating, and the oil discharge port 33 is kept open.

Further, the oil discharge port 33 is caused by the swing of the oil level or the like.
In the above configuration, the lubricating oil tends to enter, but in the above configuration, the gap 32a on the side serving as the lubricating oil inlet becomes very small along with the rotation of the weight portion 29, so that the intrusion of the lubricating oil is suppressed. Is done.

On the other hand, oil droplets scattered in the crankcase 11 and oil droplets dropped downward from the upper wall surface of the crankcase 11 are collected in the concave portion 45 on the upper surface of the housing 12. The lubricating oil in the recess 45 drops into the gear housing 25 through the communication hole 46 and is supplied to the gear 20. As a result, the gear 20 is properly lubricated.

[Brief description of the drawings]

FIG. 1 is a sectional view taken along the line AA of FIG. 3 showing one embodiment of a balancer device according to the present invention.

FIG. 2 is a sectional view of a main part of an internal combustion engine provided with the balancer device.

FIG. 3 is a sectional view taken along the line BB of FIG. 2;

FIG. 4 is a plan view of the lower housing along the line CC in FIG. 3;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Balancer device 12 ... Housing 15 ... Balancer shaft 20 ... Gear 25 ... Gear accommodating part 41, 42 ... Projection part 45 ... Depression 46 ... Communication hole

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F01M 9/10 F01M 9/08 F01M 1/06 F16F 15/26 F02B 77/00

Claims (2)

(57) [Claims] 1. A housing mounted below a cylinder block in a crankcase of an internal combustion engine, and a pair of eccentric weight portions which are rotatably housed in the housing and arranged in parallel with each other. Wherein the pair of balancer shafts have gears that mesh with each other within the housing, and one of the balancer shafts is driven by the output of the internal combustion engine, so that both balancer shafts rotate in opposite directions. A balancer device for an internal combustion engine, comprising:
That includes a recess, a balancer device for an internal combustion engine communicating hole toward the bottom of the recess into the housing interior of the gear is characterized in that it is formed through. 2. The housing, below the recess,
It has a gear housing portion for housing the gear, and the communication hole is
The balancer device for an internal combustion engine according to claim 1, wherein a bottom portion of the concave portion communicates with an upper portion of the gear housing portion.