JPH04351347A - Balance shaft of internal combustion engine - Google Patents

Abstract

PURPOSE:To enhance oil holding property of sliding surfaces and construct the whole small and light by forming a through hole penetrating the other side of a journal and provided with a plurality of openings on the other side sliding surface. while that area of the sliding surface where a max. load due to the eccentric weight part is applied which is located around the opposite side is left without formation of such a through hole. CONSTITUTION:A balance shaft 1 is furnished with a journal 2 which is supported by a bearing metal 7. An eccentric weight 3 is installed in the part on each side in the axial direction of this journal 2 and in eccentricity to one side from the axis L. Eccentric weights 3 on one side are coupled with an aux. journal 5 through a coupling part 6. Therein the journal 2 is furnished on one side with a through hole 9 having an opening 9a in the sliding surface 4a. The through hole 9 has opening except that area 4' of the sliding surface where max. load due to the eccentric weight 3 is applied which is located around the opposite side. Thereby the oil holding performance of the sliding surface 4 is enhanced, and the journal 2 itself is allowed to work as a sort of eccentric weight.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to improvements in balance shafts for internal combustion engines.

0002

[Prior Art] In an internal combustion engine that is a reciprocating engine,
In order to reduce vibration and noise, and to eliminate the inertial force caused by reciprocating masses such as pistons and connecting rods, as well as the unbalanced rotational force of the crankshaft, a cylinder is installed parallel to the crankshaft in the cylinder block and synchronized with the crankshaft. It has been known for a long time to use a rotating balance shaft, and an example of such a balance shaft is shown in FIG.
(See Publication No. 42, etc.).

The balance shaft 1 includes a journal 2 which is rotatably supported on a sliding surface 4 by a bearing in a cylinder block (not shown), and a journal 2 which is eccentric to one side from the axis of the journal 2. The sliding surface 4a on the other side, which is the side on which the eccentric weight section 3 of the journal 2 is not provided, is equal to the width of the sliding surface 4b on the one side. The journal 2 itself has an unbalanced structure, and the journal 2 acts as a kind of eccentric weight part, and the overall length of the balance shaft is shortened by that amount.

FIG. 10 (see Japanese Utility Model Application Publication No. 115651/1983) shows a hole 17 which is formed in the other side of the journal 2 and the adjacent cylindrical portion 16 in the axial direction, and the journal 2 itself is It has an unbalanced structure, and similarly to the above, the journal 2 acts as a kind of eccentric weight part, and the overall length of the balance shaft is shortened by that amount. Here, FIG. 11 is a sectional view taken along the line CC in FIG. 10.

On the other hand, there is also something like the one shown in FIG.
(See Utility Model Application Publication No. 136648/1983, etc.). The balance shaft 1 of this conventional example includes an eccentric weight part 3 between a pair of journals 2, 2, and a sliding surface (hereinafter referred to as a sliding surface) near the opposite side of the sliding surface to which the maximum load by the eccentric weight part 3 is applied. (used in the same meaning as surface 4')
A circumferential groove 18 for supplying lubricating oil is formed in the circumferential direction. This circumferential groove 18 improves oil retention on the bearing surface, prevents seizure of the journals 2, 2, and reduces sliding resistance on the other sliding surface 4a.

[0006]

[Problem to be Solved by the Invention] However, in the balance shafts as described in the above publications,
A very large load is applied to one side of the journal where the eccentric weight part is provided, and if we use a bearing that supports this journal, it can be seen that a very large fluctuating load is applied. Due to its unbalanced structure, the balance shaft flexes significantly as shown in FIG.

[0007] As described above, the journal is subjected to extremely severe usage conditions, and as shown in FIG. 8, when the sliding surface 4a (especially the sliding surface 4') on the other side is extremely reduced, The axis of the journal 2 is not concentric with the bearing that supports the journal 2 (so-called misalignment), and especially during high-speed rotation, sliding resistance increases due to deformation of the sliding surface, etc. There is a problem that it is easy to cause burn-in.
This is noticeable in a cantilevered balance shaft as shown in the figure.

In addition, in FIG. 10, the sliding surface 4 on the other side
The journal 2 itself is made to act as a kind of eccentric weight part without narrowing the width of a, but there is no suggestion of improving the oil retention of the sliding surface, and it cannot be used under the severe conditions mentioned above. However, there is a problem in that it is not possible to obtain a good lubrication condition and seizure is likely to occur.

On the other hand, in FIG. 12, a circumferential groove 18 is provided on the sliding surface 4a on the other side in order to improve the oil retention property of the sliding surface, but stress concentration occurs at the corners of the circumferential groove 18. This is especially noticeable in the vicinity of the sliding surface 4', which is subjected to the greatest bending, causing problems in the rigidity of the journal 2. Further, the imbalance of the journal 2 caused by the circumferential groove 18 is slight, and there is no suggestion that the journal 2 itself be made to act as a kind of eccentric weight part.

[0010] The present invention has been made in view of these conventional problems, and it prevents the above-mentioned misalignment and makes the journal act as a kind of eccentric weight part, and also solves the problem of rigidity of the journal. The present invention aims to provide a balance shaft for an internal combustion engine that improves the oil retention properties of sliding surfaces without causing damage.

[0011]

[Means for Solving the Problems] Therefore, the present invention provides a journal that is rotatably supported around an axis by a sliding surface, and a journal that extends from the journal in the axial direction, and that extends from the journal to one side of the axis. A balance shaft that rotates around an axis to reduce vibrations of an internal combustion engine, the balance shaft having at least an eccentric weight portion formed at an eccentric portion, the balance shaft passing through the other side of the journal,
A through hole having at least two openings was formed in the sliding surface on the other side, leaving the sliding surface near the opposite side of the sliding surface to which the maximum load by the eccentric weight part is applied.

[0012] Furthermore, when a lightweight member is loaded into the through hole, a groove-shaped oil reservoir may be formed between the opening of the through hole and the end face of the lightweight member facing the opening.

[0013]

[Function] With the above configuration, the through hole having an opening on the sliding surface improves the oil retention property of the sliding surface, and at the same time makes the journal itself an unbalanced structure, making the journal a kind of eccentric weight part. By acting as such, the diameter or length of the eccentric weight portion can be reduced while maintaining the function as a conventional balance shaft.

[0014] Also, the sliding surface on the opposite side of the sliding surface to which the maximum load is applied by the eccentric weight part (the sliding surface on which large bending is applied) is ensured to be as uniform and sufficient as the sliding surface on the one side. Therefore, even if this journal rotates at high speed while being subjected to large bending due to the eccentric weight part as described above, the axis of the journal will not easily misalign with respect to the bearing that supports this journal. It is possible to suppress the deformation of the sliding surface and reduce the sliding resistance of the sliding surface.

Furthermore, by loading a lightweight member into the through hole and forming a groove-shaped oil reservoir at the opening of the through hole, lubricating oil is reliably held against the sliding surface, preventing journal seizure and sliding. Abnormal temperature rise on the surface can be more effectively prevented.

[0016]

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

FIG. 1 shows a first embodiment of the present invention, in which a balance shaft 1 is arranged parallel to a crankshaft (not shown) and rotatably supported by a bearing provided in an engine block (not shown). It shows how things are going.

The balance shaft 1 is provided with a journal 2 that is rotatably supported by a bearing 8 via a bearing metal 7.
This journal 2 is placed eccentrically to one side from the axis L of the
It has eccentric weight parts 3, 3 extending along the axial direction from
One has a free end, and the other is connected to a sub-journal 5, which will be described later, via a connecting portion 6. Further, as is clear from FIG. 2 showing the AA cross section of FIG. 1, the eccentric weight portions 3, 3 have a semicylindrical cross-sectional shape. Here, the journal refers to a portion of the shaft supported by a bearing, and the sliding surface of the journal refers to a surface that is in contact with the bearing.

On the other hand, a through hole 9 having an opening 9a in the sliding surface 4a is formed on the other side of the journal 2, and the cross section of the through hole 9 is approximately an elongated ellipse in the figure. The sliding surface 4' near the opposite side of the sliding surface to which the maximum load from the eccentric weight section 3 is applied is left open. In addition, in this embodiment, the through hole 9 is aligned with the axis L of the journal 2.
It is formed substantially at right angles to an extension line connecting the sliding surface to which the maximum load by the eccentric weight part 3 is applied.

A sub-journal 5 coaxial with the journal 2 is formed at one end of the balance shaft 1, and is rotatably supported by a bearing 8 via a bearing metal 7. Further, although not shown in the drawings, a driving gear, etc., which receives the rotational force of the crankshaft, is formed on the side opposite to the journal 2 with respect to the sub-journal 5.

Furthermore, inside the bearing 8 and the bearing metal 7,
An oil supply path 10 is formed and communicates with a predetermined oil supply source (not shown).

Based on this configuration, the operation will be explained next.

Now, when this internal combustion engine is started, the balance shaft 1 rotates in conjunction with the crankshaft (for example, at twice the rotational speed of the crankshaft in an in-line four-cylinder engine), thereby reducing vibration and noise. Eliminates the causes of inertia caused by the reciprocating mass and unbalanced rotational force of the crankshaft.

On the other hand, the through hole 9 formed on the other side makes the journal 2 itself have an unbalanced structure, so by making the journal 2 act as a kind of eccentric weight part,
Even without increasing the diameter or length of the eccentric weight part to ensure a predetermined eccentric weight, it is possible to reduce the diameter or length of the eccentric weight part while maintaining the function as a conventional balance shaft.

[0025] Also, the sliding surface 4 on which the greatest bending is applied
' is equally and sufficiently secured as the sliding surface 4b on one side, so even if the journal 2 rotates at high speed while being subjected to large bending due to the eccentric weight part 3 as described above,
The axis of the journal 2 is less likely to be misaligned with respect to the bearing 8 that pivotally supports the journal 2, and deformation of the sliding surface 4 can be suppressed. This is particularly noticeable in cases where one end of the eccentric weight section 3 is a free end, such as in this embodiment.

Further, lubricating oil is introduced from the oil supply source to the sliding surface 4 of the journal 2 through the oil supply path 10, and a predetermined amount of lubricating oil is secured in the through hole 9. Improves oil retention and provides good lubrication.

Furthermore, in this embodiment, in order to further reduce the weight of the other side of the journal 2 and to make the journal 2 itself more unbalanced, the cross-sectional shape of the through hole 9 is made into a vertically elongated approximately elliptical shape. However, the cross section may be circular, and in this case, the same effect as described above can be obtained, and the workability of the hole is significantly improved.

FIG. 3 shows a second embodiment. FIG. 3 corresponds to the AA cross-sectional view in FIG.

The through hole 9 of the first embodiment is loaded with a lightweight member 12 such as resin or light alloy, and the opening 9 of the through hole 9 is
The end surface 12' of the lightweight member facing a substantially follows the shape of the sliding surface 4a. In this way, the opening 9a of the through hole 9 and the end surface 1 of the lightweight member facing the opening 9a are
2', a groove-shaped oil reservoir 11 substantially along the sliding surface 4a.
is formed. The other configurations are similar to those in the first embodiment, are given the same numbers, and their explanations are omitted. Here, since what is loaded into the through hole 9 is a lightweight member, the journal 2 has an unbalanced structure.

In this way, the lightweight member 12 is inserted into the through hole 9.
The rigidity of the journal 2 is increased by loading the oil, and at the same time, since the groove-shaped oil reservoir 11 is formed along the sliding surface 4a, the lubricating oil is reliably held against the sliding surface and the oil supply is facilitated. Fluctuations in the pressure of the lubricating oil led from the oil supply source when the passage 10 and the through hole 9 coincide with each other are also reduced.

Furthermore, in order to make the journal 2 itself an unbalanced structure, the interior of the lightweight member 12 may be hollow, as shown in FIG.

A third embodiment is shown in FIGS. 5 and 6. 6 is a partial view of the vicinity of the journal 2 corresponding to FIG. 1, and FIG. 5 is a sectional view taken along line BB in FIG.

The lightweight member 12a is the same as the lightweight member 12 of the second embodiment, with detachment prevention claws 13 provided on both left and right sides in the figure. Further, a recess 14 is formed at the end of the through hole 9' so that the detachment prevention claw 13 is fixed when the lightweight member 12a is loaded. This prevents the lightweight member 12a from detaching from the balance shaft 1 rotating at high speed. In this case, it is desirable for the lightweight member 12a to be an elastic body for its wearability.

FIG. 7 shows a fourth embodiment. FIG. 7 corresponds to the AA cross-sectional view of FIG.

A lid 15 is fixed to the through hole 9 by welding or caulking, and the opening of the through hole 9 and the lid 15 form a groove-shaped oil reservoir 11' approximately along the sliding surface 4a, Further, a flange portion 15' is formed on the outer periphery of the lid 15 so as to be securely fixed to the through hole 9. The other configurations are the same as those in the first embodiment, are given the same numbers, and the explanation thereof will be omitted.

The function of the groove-shaped oil reservoir 11' in this embodiment is similar to that of the groove 11 in the second embodiment and has already been explained, so the explanation thereof will be omitted. On the other hand, the lid 15 is
In addition to increasing the rigidity of the journal 2, the journal 2 itself has an unbalanced structure because the through hole 9 sandwiched between the lids 15 is hollow.

The present invention is applicable to a conventional balance shaft in which an eccentric weight portion 3 is formed via a cylindrical portion 16 that is coaxial with the journal 2, such as the balance shaft shown in FIG. is also applicable, in which case the cylindrical part 16
and the eccentric weight section 3 constitute the eccentric weight section in the above embodiment.

[0038]

[Effects of the Invention] The present invention provides a through-hole that passes through the other side of the journal and has at least two openings on the sliding surface of the other side. With a simple configuration that leaves a sliding surface,
Oil retention on the sliding surface is improved, and at the same time, journal seizure and abnormal temperature rise on the sliding surface can be prevented. On the other hand, by making the journal itself act as a kind of eccentric weight part, it is possible to reduce the size and weight of the balance shaft as a whole while maintaining its function as a conventional balance shaft. In addition, since the sliding surface near the opposite side was ensured to be as uniform and sufficient as the one side having the eccentric weight part,
Even if the journal rotates at high speed while being subjected to large bending due to the unbalanced load caused by the centrifugal force of the eccentric weight part, the axis of the journal is unlikely to misalign with respect to the bearing that supports the journal, and the sliding surface Since deformation can be suppressed,
It is possible to prevent an increase in sliding resistance, seizure of the journal, and stress concentration within the journal.

Furthermore, by loading a lightweight member into the through hole and forming a groove-shaped oil reservoir between the opening of the through hole and the end face of the lightweight member facing the opening, Oil retention is reliably improved and abnormal temperature rises on sliding surfaces can be effectively suppressed. At the same time, the rigidity of the journal is increased, so deformation of the sliding surface is suppressed, and an increase in sliding resistance and seizure of the journal can be prevented.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA in FIG. 1;

FIG. 3 is a diagram showing a second embodiment of the present invention;
Corresponds to a cross-sectional view.

FIG. 4 is a diagram showing a second embodiment of the present invention, and is a diagram showing a second embodiment of the present invention;
Corresponds to a cross-sectional view.

FIG. 5 is a diagram showing a third embodiment of the present invention;
Corresponds to a cross-sectional view.

FIG. 6 is a diagram showing a third embodiment of the present invention, and corresponds to a partial view of the vicinity of the journal in FIG. 1.

FIG. 7 is a diagram showing a fourth embodiment of the present invention, and is a diagram showing a fourth embodiment of the present invention;
Corresponds to a cross-sectional view.

FIG. 8 is a side view showing a conventional balance shaft.

9 is a side view showing a state in which the balance shaft of FIG. 8 is bent; FIG.

FIG. 10 is a side view showing a conventional balance shaft.

FIG. 11 is a sectional view taken along the line CC in FIG. 10;

FIG. 12 is a diagram showing a conventional balance shaft.

[Explanation of symbols]

1 Balance shaft 2 Journal 3 Eccentric weight part 4 Sliding surface 4a Other side sliding surface 4b One side sliding surface 4´　　Sliding surface near the opposite side 9 Through hole 9a Opening 11 Oil pool 12. Lightweight components 12' End face of lightweight member

Claims (2)

[Claims] 1. A journal that is rotatably supported on a sliding surface around an axis, and an eccentric weight part that extends from the journal in the axial direction and is formed at a portion eccentric to one side from the axis. A balance shaft that rotates around an axis to reduce vibrations of an internal combustion engine, comprising at least a through hole that penetrates the other side of the journal and has at least two openings on the sliding surface on the other side; A balance shaft for an internal combustion engine, characterized in that the shaft is formed leaving a sliding surface near the opposite side of the sliding surface to which the maximum load from the eccentric weight part is applied. 2. Loading a lightweight member into the through hole, and
2. The balance shaft for an internal combustion engine according to claim 1, wherein a groove-shaped oil reservoir is formed between the opening of the through hole and the end surface of the lightweight member facing the opening.