JP3356160B2 - 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, in Japanese Utility Model Laid-Open Publication No. Sho 62-28937, a housing is mounted below a cylinder block in a crankcase of an internal combustion engine, and a balancer shaft is rotatably housed in a pair of shaft housing chambers in the housing. A balancer device having such a configuration is shown. In this balancer device, the shaft accommodating chamber has an inner peripheral surface having a circular cross section so as to maintain a constant gap with the outer peripheral surface of the weight portion. An oil outlet is formed in the upper part of the housing to discharge the oil from the housing to the outside.

[0004] The oil discharge port extends obliquely upward along the rotation direction of the balancer shaft in the form of a passage, and is gradually narrowed toward the opening at the end. In particular, one inner wall surface of the oil discharge port which is relatively downstream with respect to the rotation of the balancer shaft,
The housing extends substantially in the radial direction of the balancer shaft, and the housing is formed as a thick portion in this portion.

[0005]

However, in the above-mentioned conventional balancer device, a part of the lubricating oil which tends to flow tangentially with the rotation of the balancer shaft is, as described above, along the radial direction of the balancer shaft. As a result, the oil collides with one of the inner wall surfaces of the extended oil discharge port, and the lubricating oil is not smoothly discharged. In addition, since the oil outlet is tapered and elongated, the oil is not easily discharged to the outside, and the lubricating oil is agitated by the balancer shaft. Therefore, an increase in friction loss, a decrease in output, and an increase in fuel efficiency are caused. Further, the stirring of the lubricating oil inside the shaft accommodating chamber makes it easy for air to be mixed into the oil, which is not preferable in terms of the lubricating performance of each part. Further, the presence of the thick portion of the housing causes a problem that the weight of the balancer device and thus the internal combustion engine increases.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention has a housing mounted below a cylinder block in a crankcase of an internal combustion engine, and an eccentric weight portion, and is rotatably housed in the housing. And a pair of balancer shafts driven in synchronization with a crankshaft, wherein the balancer shaft is radially separated from a wall of the housing surrounding the weight of the balancer shaft. step is provided with the site of the small diameter side of the step as a boundary, it is configured as Setsukabe specification circumferentially extending, and the tip end inner peripheral surface of the portion of larger diameter of the stepped as a boundary and the partition walls An oil discharge port facing the rotation direction of the balancer shaft is formed between the tip end edge and the balancer shaft.

According to the second aspect of the present invention, the housing has a pair of shaft storage chambers for respectively storing the pair of balancer shafts, and each of the shaft storage chambers is provided with the oil discharge port.

[0008] Lubricating oil that is going to circulate with the rotation of the balancer shaft is discharged in a tangential direction from an oil discharge port provided at a step of the wall of the housing. At this time, while the internal space and the oil outlet of the housing the balancer shaft rotates, because it is bounded by specification Setsukabe extending in the circumferential direction, the flow of the lubricating oil, deposited by the viscosity balancer shaft Those that are going to orbit and those that are discharged from the oil discharge port are separated smoothly. In other words, the lubricating oil flow is smoothly discharged from the oil discharge port without causing unnecessary collision or stirring of the lubricating oil flow near the oil discharge port.

[0009]

[0010]

According to the balancer device for an internal combustion engine according to the present invention, collision and agitation of the lubricating oil flow near the oil discharge port can be avoided, and the lubricating oil flows efficiently from the shaft accommodating chamber in the housing through the oil discharge port. Can be discharged. Therefore, the friction loss due to the collision between the weight portion and the lubricating oil flow can be reduced, and the mixing of air due to the stirring of the lubricating oil can be suppressed.

[0011]

[0012]

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 a balancer device 1 according to the present invention. A frame-shaped oil pan is provided on a lower flange 4 of a skirt 3 of a cylinder block 2. 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. 1, the left and right shaft receiving chambers 21 are formed independently of each other. 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 in a stepped portion so as to face the balancer shaft 15 in the rotation direction.

In other words, the arc-shaped wall of the housing lower 14 constituting the shaft accommodating chamber 21 is cut off in the vicinity of the lowermost portion, and one edge is directed to the inner peripheral side.
Steps 41 are provided in the radial direction so that the other edge is located on the outer peripheral side. The portion on the small diameter side with the step 41 as a boundary extends in the circumferential direction .
Constitute a specification Setsukabe 42, between the leading edge of the step 41 as a boundary and the leading end inner peripheral surface 43 of the portion of larger diameter the partition wall 42, the oil discharge port 33 is formed.

3 and 4, when viewed in the axial direction of the balancer shaft 15, the oil discharge port 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. In this embodiment, the inner peripheral surfaces 23a, 24a of the respective weight accommodating portions 23, 24 are not completely cylindrical surfaces in the axial direction, but have a shape in which the central portion is slightly thinner and the diameter becomes larger toward both ends. ing. In other words, the oil outlet 33 has a gentle tapered surface from the central portion in the axial direction. Accordingly, the oil outlet 33
In the central portion of each of the weight accommodating portions 23 and 24 having no, a step 34 in the rotation direction is formed in a shape bent in a mountain shape as shown in FIG. The step 34 is continuous with the above-described step 41 having the oil discharge port 33. 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.

[0021] Here, in the oil discharge port 33, form a vicinity of a region indicated by reference numeral 32a in which the housing 12, and the oil discharge port 33, bounded by specification Setsukabe 42 extending in the circumferential direction Therefore, the flow of the lubricating oil caused by the rotation of the balancer shaft 15 is smoothly separated into one that is going to go around while being attached to the balancer shaft 15 due to its viscosity and one that is discharged from the oil discharge port 33. You. In other words, the lubricating oil flow is smoothly discharged from the oil discharge port 33 without causing unnecessary collision or stirring of the lubricating oil flow near the oil discharge port 33.

The oil level in the crankcase 11 is located below the housing 12 when the engine is running, and the oil discharge port 33 is kept open.

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. Moreover, as shown in FIG. 1, the wall on the large diameter side with the step 41 as a boundary covers the oil discharge port 33 from the outer peripheral side, so that the lubricating oil is more difficult to enter.

Therefore, the accumulation of the lubricating oil in the weight accommodating portions 23 and 24 can be prevented, and the friction loss due to the collision with the weight portion 29 can be reduced. Further, since the agitation of the lubricating oil is suppressed, the intrusion of air into the lubricating oil is reduced accordingly.

[0025]

[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 21 ... Shaft accommodating chamber 22 ... 1st bearing part 23 ... 1st weight accommodating part 24 ... 2nd weight accommodating part 26 ... 2nd bearing part 33 ... Oil discharge port 41 ... Step 42 ... Partition wall

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

Claims (2)

(57) [Claims] 1. A housing mounted below a cylinder block in a crankcase of an internal combustion engine and having an eccentric weight portion, rotatably housed in the housing, and driven in synchronization with a crankshaft. A balancer device for an internal combustion engine comprising: a pair of balancer shafts, wherein a wall portion of the housing surrounding the weight portion of the balancer shaft is provided with a step which is separated in a radial direction. site of the small diameter side as a boundary is configured as Setsukabe specification extending circumferentially, and between the tip end portions of the front end inner peripheral surface and the partition wall of the large diameter side of the step as a boundary, the balancer An balancer device for an internal combustion engine, wherein an oil discharge port facing the rotation direction of the shaft is formed to be open. 2. The housing has a pair of shaft housing chambers for housing a pair of balancer shafts, respectively.
2. A balancer device for an internal combustion engine according to claim 1, wherein said oil discharge port is provided in each shaft accommodating chamber.