JP2008144603A - Bearing lubrication structure of balance shaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing lubrication structure of a balance shaft, capable of sufficiently supplying lubricating oil to the high bearing pressure side, particularly, a maximum bearing pressure part, without enlarging a hydraulic pump, in an internal combustion engine. <P>SOLUTION: The opening center 12b of a lubricating oil delivery port 12a exists in an area Ra up to a phase Qp of rotational front 90 degrees of the balance shaft 2 from a maximum bearing pressure phase Mp, and is also arranged in a phase adjacent to a high abrasion phase area Xa even in this area. The lubricating oil delivery port having the opening center is not formed in the other phase area except for this area Ra. Thus, the lubricating oil supplied from the lubricating oil delivery port 12a is supplied to the high abrasion phase area Xa including the maximum bearing pressure phase Mp at a short distance by rotation of the balance shaft 2. Thus, effective lubrication can be performed by supplying a large quantity of lubricating oil to the high abrasion phase area Xa including the maximum bearing pressure phase Mp before discharging the lubricating oil from a bearing surface. Thus, the problem is solved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a bearing lubrication structure for a balance shaft that reduces vibration of an internal combustion engine by rotating an eccentric mass portion in conjunction with the rotation of the internal combustion engine.

As a mechanism for reducing vibration caused by piston motion of an internal combustion engine, a balance shaft is used in which an eccentric mass portion is provided and the center of gravity is shifted from the center of rotation. As a structure for supplying lubricating oil to the bearing portion of such a balance shaft, an oil passage is formed in the balance shaft in the axial direction, and an oil passage communicating at right angles to the oil passage is penetrated into the bearing portion of the balance shaft. (See, for example, Patent Documents 1, 2, and 3).
Japanese Utility Model Publication No. 63-15347 (page 5-8, FIG. 1) JP 2002-349222 A (page 4, FIG. 1) Japanese Patent Laying-Open No. 2005-16644 (page 5-8, FIG. 2)

  In Patent Documents 1 and 2, as a lubricating oil discharge port for supplying lubricating oil to the bearing portion, the oil passage perpendicular to the axis of the balance shaft passes through the entire balance shaft, so that the phase differs by 180 degrees. Lubricating oil was supplied from two discharge ports.

  In such a supply form by the arrangement of the discharge ports, the supply amount from the oil passage at the center of the shaft is divided into two parts, particularly for the part where lubrication is important, that is, the high surface pressure part generated by the rotation of the eccentric mass part. The oil pressure at the discharge port decreases, and the amount of oil supplied to the high pressure surface portion becomes extremely small. Furthermore, even in the high surface pressure portion, there is a tendency that the lubricating oil is particularly difficult to enter the maximum surface pressure portion corresponding to the central phase portion of the eccentric mass portion. Therefore, in the supply forms of Patent Documents 1 and 2, the supply amount with respect to the high surface pressure portion is greatly reduced. In particular, in the highest surface pressure portion, it is very difficult to supply the lubricating oil, and the oil film may be cut. For this reason, it is necessary to supply a large amount of oil at high pressure from the oil passage on the shaft center side, and the amount of oil discharged from the low surface pressure side also becomes large. It becomes.

  In Patent Document 3, dispersion of the supply amount of the lubricating oil is prevented by using one lubricating oil discharge port connected to the axial oil passage without branching. However, the technical idea that determines the arrangement of the lubricating oil discharge port here is based on the objective of supplying the lubricating oil without being blocked by the surface pressure. That is, it is assumed that the lubricating oil discharge port is arranged in a region opposite to the eccentric mass portion. However, even if the lubricating oil is discharged on the low surface pressure side in this way, the amount of oil that reaches the high surface pressure side is a part of the amount of discharged oil, and the amount is further reduced at the maximum surface pressure portion. Accordingly, in order to sufficiently distribute the lubricating oil to the maximum surface pressure portion, it is necessary to supply a large amount of oil from the axial center oil passage to the discharge port. Therefore, it is necessary to increase the size of the hydraulic pump to some extent, and it cannot be said that the problem of deterioration of fuel consumption of the internal combustion engine is sufficiently solved.

  An object of the present invention is to provide a bearing lubrication structure for a balance shaft that can sufficiently supply lubricating oil to the high surface pressure side, particularly to the highest surface pressure portion without causing an increase in size of the hydraulic pump.

In the following, means for achieving the above object and its effects are described.
The bearing lubrication structure for a balance shaft according to claim 1 is a bearing lubrication structure for a balance shaft that reduces vibration of the internal combustion engine by rotating an eccentric mass portion in conjunction with the rotation of the internal combustion engine. The outer peripheral surface of the formed journal portion is connected to a lubricating oil supply oil passage formed in the shaft of the balance shaft, and 90 degrees forward of the balance shaft rotation from the maximum surface pressure phase at which the surface pressure becomes maximum when the balance shaft rotates. The lubricating oil discharge port having the opening center disposed in the region up to is formed, and the lubricating oil discharge port having the opening center in the other phase region is not formed.

  As described above, the center of the lubricating oil discharge port exists in the region from the maximum surface pressure phase to 90 degrees forward of the balance shaft rotation. And the lubricating oil discharge port which has an opening center in other phase area | regions other than this area | region is not formed.

  For this reason, since the hydraulic pressure is applied only to the high surface pressure side, a large amount of lubricating oil does not escape from the low pressure surface side, and the hydraulic pump is large without causing a decrease in oil pressure compared to the case where there is a discharge port on the low pressure surface side. A sufficient amount of lubricating oil can be supplied to the high surface pressure side without conversion.

  In addition, the discharge position is not one of the high pressure surfaces, but the region from the maximum surface pressure phase to 90 degrees forward of the balance shaft rotation. Thus, the lubricating oil supplied from the lubricating oil discharge port is supplied to the maximum surface pressure phase at a short distance by the rotation of the balance shaft. Therefore, a large amount of lubricating oil can be supplied to the maximum surface pressure phase portion before the lubricating oil is discharged from between the journal portion and the journal bearing corresponding thereto. Therefore, effective lubrication is possible.

As a result, the lubricating oil can be sufficiently supplied to the high surface pressure side, particularly to the highest surface pressure portion, without increasing the size of the hydraulic pump.
The bearing lubrication structure for a balance shaft according to claim 2, wherein the lubricant outlet is formed by the eccentric mass portion in a region from the highest surface pressure phase to 90 degrees forward of the balance shaft rotation. The center of the opening is arranged in the phase region.

As described above, the lubricating oil discharge port is present in the phase region where the eccentric mass portion is formed even in the region where the center of the opening is from the maximum surface pressure phase to 90 degrees forward of the balance shaft rotation.
As a result, the lubricating oil supplied from the lubricating oil discharge port is supplied to a phase having a particularly high surface pressure, thereby enabling effective lubrication.

  The balance shaft bearing lubrication structure according to claim 3 is characterized in that, in claim 1 or 2, no portion of the lubricating oil discharge port is arranged in the highest surface pressure phase.

  When a part of the lubricating oil discharge port is disposed at the portion of the maximum surface pressure phase, the bearing area is reduced by the lubricating oil discharge port, and the surface pressure increases accordingly. Therefore, in order not to increase the surface pressure more than necessary and to facilitate the formation of the lubricating oil film, a configuration in which any part of the lubricating oil discharge port is not disposed in the maximum surface pressure phase is preferable.

  In the bearing lubrication structure for a balance shaft according to claim 4, in any one of claims 1 to 3, no portion of the lubricating oil discharge port is disposed in the other phase region. To do.

  In the other phase region, not only the center of the opening but also any part of the lubricating oil discharge port is arranged, so that it is possible to effectively prevent the lubricating oil from escaping to the low pressure surface side. It becomes easy to maintain the amount of lubricating oil supplied to the side.

  In the bearing lubrication structure for a balance shaft according to claim 5, in any one of claims 1 to 4, no portion of the lubricating oil discharge port is disposed in the highest surface pressure phase, and the highest surface pressure is provided. It arrange | positions at the phase adjacent to a phase, It is characterized by the above-mentioned.

  As described above, the surface pressure is not increased more than necessary by arranging the lubricating oil discharge port at a phase adjacent to the maximum surface pressure phase without disposing any portion at the maximum surface pressure phase. At the same time, since the lubricating oil from the lubricating oil discharge port can reach the maximum surface pressure phase in the shortest distance, effective lubrication becomes possible.

  In the bearing lubrication structure for a balance shaft according to claim 6, in any one of claims 1 to 4, a high wear phase region having a predetermined phase width is set around the highest surface pressure phase, and the high wear phase region is set in the high wear phase region. Is characterized in that no part of the lubricating oil outlet is arranged.

  It is preferable not to raise the surface pressure not only at the maximum surface pressure phase portion but also at the peripheral portions in order to facilitate the formation of the lubricating oil film and to suppress wear of the bearing surface. Therefore, by setting up a high wear phase region with a predetermined phase width centered on the highest surface pressure phase by experiment and the like, by configuring such that no part of the lubricating oil discharge port is arranged in this high wear phase region, With sufficient lubrication in the high wear phase region, the wear resistance of the balance shaft can be improved.

A bearing lubrication structure for a balance shaft according to a seventh aspect is characterized in that, in the sixth aspect, the lubricating oil discharge port is arranged in a phase adjacent to the high wear phase region.
In this way, by not arranging any part of the lubricant discharge port in the high wear phase region, but in a phase adjacent to the high wear phase region, the surface pressure is more than necessary in the high wear phase region. In addition, the lubricating oil from the lubricating oil outlet can reach the high wear phase region in the shortest distance, so that effective lubrication is possible.

[Embodiment 1]
FIG. 1 shows a front view of a main portion of a balance shaft 2 to which the above-described invention is applied and a bearing lubrication structure thereof. 2 is a cross-sectional view taken along line AA in FIG. A journal portion 6 having a slightly larger diameter than the shaft body 4 is formed on the shaft body 4 of the balance shaft 2 with the same axis. Further, the shaft body 4 is formed with an eccentric mass portion 8 in a fan shape.

  A lubricating oil supply oil passage 10 is formed at the axial center position of the shaft body 4. The front end portion of the lubricating oil supply oil passage 10 is closed by a steel ball 10a, but a lubricating oil supply oil passage 12 bent at a right angle from the lubricating oil supply oil passage 10 is branched and formed in the middle of the journal portion 6. The lubricating oil discharge port 12a is formed in the outer peripheral surface 6a. The opening center 12b of the lubricating oil discharge port 12a has a phase Qp 90 degrees ahead of the rotation of the balance shaft 2 from the maximum surface pressure phase Mp at which the surface pressure generated by the centrifugal force of the eccentric mass portion 8 becomes maximum when the balance shaft 2 rotates. It is formed so as to be included in the region Ra. In addition, as shown by the arrow V, the rotation direction of the balance shaft 2 is counterclockwise in FIG.

  Further, also in the region Ra, the opening center 12b of the lubricating oil discharge port 12a is out of the maximum surface pressure phase Mp, and any part of the lubricating oil discharge port 12a is not disposed in the maximum surface pressure phase Mp.

  Here, a high wear phase region Xa in which wear is likely to proceed due to high surface pressure around the highest surface pressure phase Mp is set in advance by experiments, simulation calculations, or the like. In the present embodiment, no part of the lubricating oil discharge port 12a is disposed in the high wear phase region Xa, and the entire lubricating oil discharge port 12a is disposed at a phase position adjacent to the high wear phase region Xa. Yes.

  Therefore, when the journal portion 6 is supported by the journal bearing J (FIG. 2) by applying the balance shaft 2 to the internal combustion engine, the journal bearing J is highly worn immediately after the rotation of the lubricant discharge port 12a. The phase region Xa is rotated. For this reason, the lubricating oil supplied between the outer peripheral surface 6a of the journal portion 6 and the inner peripheral surface of the journal bearing J from the lubricating oil discharge port 12a is immediately supplied to the high wear phase region Xa.

According to the first embodiment described above, the following effects can be obtained.
(I). As described above, the lubricating oil discharge port 12a has the opening center 12b in the region Ra from the maximum surface pressure phase Mp to the phase Qp 90 degrees forward of the balance shaft 2. And the lubricating oil discharge port which has an opening center in other phase area | regions other than this area | region Ra is not formed.

  For this reason, the hydraulic pressure is applied only between the journal portion 6 and the journal bearing J on the high surface pressure side (the maximum surface pressure phase Mp side with the center passage line Lm in FIG. 2 as a boundary). A large amount of lubricating oil does not escape from the side opposite to the maximum surface pressure phase Mp with the passage line Lm as a boundary. Therefore, a sufficient amount of lubricating oil can be supplied to the high surface pressure side without increasing the size of the hydraulic pump without causing a decrease in oil pressure as compared with the case where the discharge port is provided on the low pressure surface side.

  In addition, the discharge position is not one of the high pressure surfaces, but is a region Ra from the maximum surface pressure phase Mp to the phase Qp 90 degrees ahead of the rotation of the balance shaft 2, and also in this, the phase adjacent to the high wear phase region Xa It is arranged. Accordingly, the lubricating oil supplied from the lubricating oil discharge port 12a is supplied to the high wear phase region Xa including the maximum surface pressure phase Mp at a short distance by the rotation of the balance shaft 2. For this reason, before lubricating oil is discharged from between the journal portion 6 and the journal bearing J, a large amount of lubricating oil can be supplied to the high wear phase region Xa including the maximum surface pressure phase Mp. Therefore, effective lubrication is possible.

As a result, the lubricating oil can be sufficiently supplied to the high surface pressure side, particularly to the highest surface pressure portion (maximum surface pressure phase Mp) without increasing the size of the hydraulic pump.
(B). In particular, the surface pressure tends to increase in the phase region where the eccentric mass portion 8 is formed when the balance shaft 2 rotates. Therefore, as in the present embodiment, the lubricating oil discharge port 12a is disposed in the phase region where the eccentric mass portion 8 exists even in the region Ra, so that more effective lubricating oil can be supplied. In the present embodiment, the region Ra is a phase region where the eccentric mass portion 8 exists. Therefore, if it is in area | region Ra, it will become a phase area | region where the eccentric mass part 8 exists.

  (C). None of the portions of the lubricant discharge port 12a is arranged at the maximum surface pressure phase Mp. Further, no portion of the lubricant discharge port 12a is arranged for the high wear phase region Xa.

  If even a part of the lubricating oil discharge port 12a belongs to the portion of the maximum surface pressure phase Mp, the bearing area of the journal portion 6 is reduced by the lubricating oil discharge port 12a, and the surface pressure increases accordingly. Therefore, it is more preferable in terms of formation of the lubricating oil film that no part of the lubricating oil discharge port 12a is disposed in the maximum surface pressure phase Mp. Further, it is preferable not to raise the surface pressure even in the vicinity of the maximum surface pressure phase Mp in order to facilitate the formation of a lubricating oil film and to suppress the wear of the journal portion 6 and the bearing surface of the journal bearing J. .

  Therefore, as described above, by configuring such that no portion of the lubricant discharge port 12a is disposed in the high wear phase region Xa set with the maximum surface pressure phase Mp as the center, sufficient lubrication in the high wear phase region Xa is achieved. As a result, the wear resistance of the balance shaft 2 can be improved.

  (D). Further, not only the opening center 12b of the lubricating oil supply oil passage 12 but also any portion of the lubricating oil discharge port 12a is not disposed in the other phase region, particularly on the low pressure surface side. This can effectively prevent the lubricating oil from escaping to the low pressure surface side, and it is easy to maintain the amount of lubricating oil supplied to the high pressure surface side.

[Other embodiments]
(A). Depending on the degree of the surface pressure of the balance shaft, the lubricating oil discharge port may not be arranged at the phase position as described in the above embodiment, but may be arranged as shown in the sectional view of FIG.

  In the balance shaft 102 shown in FIG. 3A, the lubricating oil discharge port 112a of the lubricating oil supply oil passage 112 is not arranged in the region Ra and at any portion in the maximum surface pressure phase Mp. The lubricant discharge port 112a is arranged in a phase adjacent to the maximum surface pressure phase Mp.

  This makes it possible to sufficiently supply the lubricating oil to the high surface pressure side, particularly the highest surface pressure portion without increasing the size of the hydraulic pump, and to prevent the surface pressure from being increased more than necessary. Since the lubricating oil from the outlet 112a can reach the maximum surface pressure phase Mp in the shortest distance, effective lubrication is possible.

  In the balance shaft 202 shown in FIG. 3B, the lubricating oil discharge port 212a of the lubricating oil supply oil passage 212 is in the region Ra, and any portion rotates the balance shaft 202 from the maximum surface pressure phase Mp. It is out of phase Qp of 90 degrees forward. Therefore, no part of the lubricant discharge port 212a is arranged on the low pressure surface side.

  This makes it possible to sufficiently supply the lubricating oil to the high surface pressure side, particularly the highest surface pressure portion, without effectively increasing the size of the hydraulic pump, and to effectively prevent the lubricating oil from escaping to the low pressure surface side. It becomes easy to maintain the amount of lubricating oil supplied to the high-pressure surface side.

  In the balance shaft 302 shown in FIG. 3C, the opening center 312b of the lubricating oil discharge port of the lubricating oil supply oil passage 312 is disposed at the phase Qp 90 degrees ahead of the rotation of the balance shaft 302 relative to the maximum surface pressure phase Mp. It is not arranged on the low surface pressure side any more.

This makes it possible to sufficiently supply the lubricating oil to the high surface pressure side, particularly to the highest surface pressure portion, without increasing the size of the hydraulic pump.
In the balance shaft 402 shown in FIG. 3D, the opening center 412b of the lubricating oil discharge port of the lubricating oil supply oil passage 412 is arranged at the maximum surface pressure phase Mp, and more than this is arranged on the rotation rear side. It has not been.

This makes it possible to sufficiently supply the lubricating oil to the high surface pressure side, particularly to the highest surface pressure portion, without increasing the size of the hydraulic pump.
(B). In FIG. 4, the phase widths of the eccentric mass portions 508 and 608 are narrower than those in the above-described embodiment, and as a result, the region Ra from the maximum surface pressure phase Mp to the phase Qp 90 degrees ahead of the rotation of the balance shafts 502 and 602. In the example, there is a phase region in which the eccentric mass portions 508 and 608 do not exist. In the configuration as shown in FIG. 4, lubricating oil discharge ports 512a and 612a may be arranged as shown.

  In the balance shaft 502 shown in FIG. 4A, the opening center 512b of the lubricating oil discharge port 512a of the lubricating oil supply oil passage 512 is disposed at the front end phase position Wp of the eccentric mass portion 508 in the region Ra. .

  This makes it possible to sufficiently supply the lubricating oil to the high surface pressure side, particularly to the highest surface pressure portion, without increasing the size of the hydraulic pump. Furthermore, especially in the phase region where the eccentric mass portion 508 is formed when the balance shaft 502 rotates, the surface pressure tends to increase. Therefore, as shown in FIG. 4A, the opening center 512b of the lubricating oil discharge port 512a is arranged in the phase region where the eccentric mass portion 508 exists even within the region Ra, so that more effective supply of lubricating oil can be achieved. Can do.

  In the balance shaft 602 shown in FIG. 4B, the lubricating oil outlet 612a of the lubricating oil supply oil passage 612 is formed inside the front end phase position Wp of the eccentric mass portion 608, that is, the eccentric mass portion 608 is formed. It is arranged inside the phase region. With this configuration, the effect shown in FIG. 4A is produced, and the lubricating oil can be easily supplied to the maximum surface pressure phase Mp and the high wear phase region Xa.

  (C). In each of the above embodiments, the journal portion is formed at a position other than the eccentric mass portion in the axial direction. However, when the eccentric mass portion is formed long in the axial direction, a part of the eccentric mass portion is arranged around the rotation axis. It is good also as a journal part formed in a circle. Also in this case, the configuration of each of the above embodiments can be applied, and the same effect is produced.

  (D). In each of the above embodiments, one lubricating oil discharge port is provided in one journal portion, but a plurality of lubricating oil discharge ports may be provided in the axial direction. Further, a plurality of them may be arranged in the circumferential direction as long as the phase positions of the above embodiments are satisfied.

  In each of the above embodiments, the shape of the lubricating oil discharge port is circular, but it may be elongated in the circumferential direction or may be elongated in the axial direction.

The front view which shows the balance shaft of Embodiment 1, and its bearing lubrication structure. AA sectional view taken on the line AA of FIG. Arrangement explanatory drawing of the lubricating oil discharge opening in the balance shaft of other embodiments, and its bearing lubrication structure. Arrangement explanatory drawing of the lubricating oil discharge opening in the balance shaft of other embodiments, and its bearing lubrication structure.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 2 ... Balance shaft, 4 ... Shaft body, 6 ... Journal part, 6a ... Outer peripheral surface, 8 ... Eccentric mass part, 10 ... Lubricant oil supply oil path, 10a ... Steel ball, 12 ... Lubricant oil supply oil path, 12a ... Lubrication Oil discharge port, 12b ... opening center, 102 ... balance shaft, 112 ... lubricating oil supply oil passage, 112a ... lubricating oil discharge port, 202 ... balance shaft, 212 ... lubricating oil supply oil passage, 212a ... lubricating oil discharge port, 302 ... balance shaft, 312 ... lubricating oil supply oil passage, 312b ... opening center of lubricating oil discharge port, 402 ... balance shaft, 412 ... lubricating oil supply oil passage, 412b ... opening center of lubricating oil discharge port, 502 ... balance shaft, 508: Eccentric mass part, 512: Lubricating oil supply passage, 512a: Lubricating oil discharge port, 512b ... Center of opening, 602 ... Balance shaft, 608 ... Eccentric mass part, 61 ... Lubricating oil supply oil path, 612a ... Lubricating oil discharge port, J ... Journal bearing, Lm ... Center passage line, Mp ... Maximum surface pressure phase, Qp ... 90 degree phase forward of rotation of balance shaft, Ra ... Area, Wp ... Front end phase position, Xa ... high wear phase region.

Claims (7)

A balance shaft bearing lubrication structure that reduces vibration of the internal combustion engine by rotating the eccentric mass portion in conjunction with the rotation of the internal combustion engine,
The outer peripheral surface of the journal part formed on the balance shaft is connected to the lubricating oil supply passage formed in the shaft of the balance shaft, and the balance shaft rotates from the maximum surface pressure phase where the surface pressure becomes maximum when the balance shaft rotates. 2. A bearing lubrication structure for a balance shaft, wherein a lubricating oil discharge port having an opening center disposed in a region up to 90 degrees forward is formed, and no lubricating oil discharge port having an opening center in another phase region is formed. In Claim 1, the said lubricating oil discharge outlet has arrange | positioned the opening center in the phase area | region in which the said eccentric mass part is formed in the area | region from the said highest surface pressure phase to 90 degrees ahead of balance shaft rotation. The bearing lubrication structure of the balance shaft characterized by The bearing lubrication structure for a balance shaft according to claim 1, wherein none of the lubricating oil discharge ports are arranged in the maximum surface pressure phase. The bearing lubrication structure for a balance shaft according to any one of claims 1 to 3, wherein any portion of the lubricant discharge port is not disposed in the other phase region. In any one of Claims 1-4, the said lubricating oil discharge port is arrange | positioned in the phase which is not arrange | positioned in the said highest surface pressure phase in any part, and the said highest surface pressure phase. Bearing shaft bearing lubrication structure. The high wear phase region having a predetermined phase width is set around the highest surface pressure phase as defined in any one of claims 1 to 4, and any portion of the lubricating oil discharge port is disposed in the high wear phase region. The bearing lubrication structure of the balance shaft is characterized by not. The bearing lubrication structure for a balance shaft according to claim 6, wherein the lubricant discharge port is disposed in a phase adjacent to the high wear phase region.

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