JP4988647B2 - Structure of oil drop passage in internal combustion engine - Google Patents

Description

  The present invention relates to a structure of an oil dropping passage in an internal combustion engine having a balance shaft that rotates in conjunction with a crankshaft, in which lubricating oil on the upper surface of the cylinder head is guided into a crankcase at a lower portion of the cylinder block. .

  In general, in an internal combustion engine having a balance shaft that rotates in conjunction with a crankshaft, a balance shaft housing is formed in a crankcase at the bottom of the cylinder block, and the balance shaft is placed in the balance shaft housing. It is configured to be supported in parallel with the shaft.

In this case, in Patent Document 1 as a prior art, in addition to the oil drop passage from the cylinder head on the upper surface of the cylinder block communicating with the crankcase through the balance shaft housing, the oil drop passage is provided. Among them, it is described that the opening into the balance shaft housing is located in a portion adjacent to the metal-type bearing portion with respect to the balance shaft.
Japanese Utility Model Publication No. 64-46411

  According to this prior art configuration, the lubricating oil on the upper surface of the cylinder head can smoothly flow down to the crankcase through the oil passage and the balance shaft housing, and in addition, the lubricating oil flowing down the oil dropping passage can be reduced. The portion can be used for lubrication of the bearing portion with respect to the balance shaft.

  However, on the other hand, when the lubricating oil flowing down through the oil dropping passage flows down one side of the bearing portion of the balance shaft, only a part of the lubricating oil enters the metal bearing portion. This does not force the flow of the inside of the part, so there is a risk of lack of lubricating oil in the bearing part, and fine powder such as metal wear powder tends to accumulate, and this fine powder increases wear. There was a problem.

  It is a technical object of the present invention to provide an oil dropping passage structure that solves these problems.

In order to achieve this technical problem, the present invention
“In the balance shaft housing provided in the crankcase of the cylinder block, a balance shaft that rotates in conjunction with the crankshaft is rotatably supported, while an oil drop passage from the cylinder head on the upper surface of the cylinder block is provided In an internal combustion engine provided to communicate with the crankcase through a balance shaft housing,
One end of the balance shaft is pivotally supported by a ball bearing that fits into a bearing hole, and the inner side surface of the left and right side surfaces of the ball bearing is opened into the balance shaft housing, while the outer side surface is An oil chamber formed inside a bearing cover that closes the bearing hole was opened, and a portion of the oil dropping passage upstream of the balance shaft housing was communicated with the oil chamber. "
It is characterized by that.

  In this configuration, part of the lubricating oil flowing from the cylinder head through the oil dropping passage flows into the oil chamber of the bearing cover.

  In this case, the outer side surface of the ball bearing that pivotally supports one end of the balance shaft is opened in the oil chamber, while the inner side surface of the ball bearing is opened in the balance shaft housing. As a result, the lubricating oil that has entered the oil chamber flows out into the balance shaft housing through the gap between the outer ring and the inner ring of the ball bearing, and the balance shaft in the balance shaft housing. The lubricating oil flows directly into the housing from the oil dropping passage and flows out of the balance shaft housing into the crankcase.

  In other words, a part of the lubricating oil flowing down from the cylinder head through the oil dropping passage flows through the inside of the ball bearing that pivotally supports one end of the balance shaft so as to cross the axial direction. The ball bearing can be accurately and forcibly lubricated, and it is possible to reliably reduce the accumulation of fine powder such as metal wear powder on the ball bearing.

  In addition, the lubricating oil crossing the inside of the ball bearing enters the balance shaft housing, merges with the lubricating oil directly flowing into the balance shaft housing from the oil dropping passage, and then flows out into the crankcase. Since the amount of oil mist generated in the crankcase due to a part of the lubricating oil crossing the ball bearing can be greatly suppressed, the lubrication that disappears together with the exhaust of blow-by gas in the crankcase. An increase in oil can be reliably avoided.

  Embodiments of the present invention will be described below with reference to FIGS.

  In this figure, reference numeral 1 denotes a cylinder block comprising a cylinder 2, and reference numeral 3 denotes a cylinder head fastened to the upper surface of the cylinder block 1 so as to close the top of the cylinder 2.

  A crankcase 4 is integrally provided at a lower portion of the cylinder block 1, and a crankshaft 6 that is rotated by a reciprocating motion of a piston 5 in the cylinder 2 is pivotally supported on the crankcase 4.

  A cylindrical balance shaft housing 7 is provided on one side surface of the crankcase 4 so as to extend in parallel with the crankshaft 6. The balance shaft housing 7 includes the crankshaft 6. A balance shaft 8 that rotates in conjunction with the shaft is rotatably supported.

  One end portion of the balance shaft 8 is inserted into the ball bearing 10 inserted in the bearing hole 9 in the crankcase 4 by inserting a journal portion 8a provided integrally with the one end portion. It is supported.

  The ball bearing 10 is fixed in the bearing hole 9 by a bearing cover 11 attached to the crankcase 4 so as to close the bearing hole 9. The bearing cover 11 is attached to the crankcase 4 on the outer periphery thereof. The plurality of bolts 12 arranged are detachable.

  On the other hand, the inner side surface 10a of the left and right side surfaces 10a and 10b of the ball bearing 10 is open in the balance shaft housing 7, while the outer side surface 10b is an oil chamber formed in the bearing cover 11. 13 is open.

  Inside the cylinder block 1, a first oil drop passage 14 from a valve mechanism chamber (not shown) on the upper surface of the cylinder head 3 and an oil chamber 15 in which the lower end of the first oil drop passage 14 communicates. The balance shaft housing 7 communicates with the crankcase 4 via the second oil drop passage 16.

  The oil chamber 15 communicates with a portion adjacent to the ball bearing 10 in the balance shaft housing 7 through the first passage 17, while in the bearing cover 11 through the second passage 18. It communicates with the oil chamber 13.

  In this configuration, the lubricating oil flowing down in the first oil dropping passage 14 enters the oil chamber 15.

  A portion of the lubricating oil that has entered the oil chamber 15 flows directly into the balance shaft housing 7 through the first passage 17 as indicated by an arrow A, while entering the oil chamber 15. As shown by an arrow B, the remainder flows into the oil chamber 13 in the bearing cover 11 via the second passage 18.

  In this case, the outer side surface 10b of the ball bearing 10 that pivotally supports one end of the balance shaft 8 is opened in the oil chamber 13, while the inner side surface 10a of the ball bearing 10 is balanced. Due to the opening in the shaft housing 7, the lubricating oil that has entered the oil chamber 13 flows into the balance shaft housing 7 through the gap between the outer ring and the inner ring in the ball bearing 10. In the balance shaft housing 7, the lubricating oil that flows directly into the balance shaft housing 7 from the first passage 17 is joined, and the crankcase is inserted into the balance shaft housing 7 from the second oil drop passage 16. To 4

  Further, the balance shaft 8 functions as a centrifugal pump by its rotation, so that lubricating oil introduced from the oil chamber 13 through the ball bearing 10 into the balance shaft housing 7 is balanced with the balance shaft 8. Since the operation of sucking into the housing 7 is performed, the amount of lubricating oil passing through the ball bearing 10 can be increased.

  In the embodiment, the oil chamber 15 is formed by being recessed by casting or the like so as to open on the side surface of the cylinder block 1, and the opening is closed by the plug body 19. On the other hand, the second passage 18 is formed by being depressed by casting or the like so as to open on the side surface of the cylinder block 1, and the opening is closed by the bearing cover 11.

It is a vertical front view which shows embodiment of this invention. FIG. 2 is a sectional view taken along line II-II in FIG. 1. FIG. 3 is a sectional view taken along line III-III in FIG. 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylinder block 2 Cylinder 3 Cylinder head 4 Crankcase 5 Piston 6 Crankshaft 7 Balance shaft housing 8 Balance shaft 9 Bearing hole 10 Ball bearing 11 Bearing cover 13 Oil chamber 14 First oil drop passage 15 Oil chamber 16 Second oil drop passage

Claims (1)

A balance shaft that rotates in conjunction with the crankshaft is rotatably supported in a balance shaft housing provided in the crankcase of the cylinder block, while an oil drop passage from the cylinder head on the top surface of the cylinder block is provided to the balance block. In an internal combustion engine provided to communicate with the crankcase through a shaft housing,
One end of the balance shaft is pivotally supported by a ball bearing that fits into a bearing hole, and the inner side surface of the left and right side surfaces of the ball bearing is opened into the balance shaft housing, while the outer side surface is An internal combustion engine characterized by being opened to an oil chamber formed inside a bearing cover that closes the bearing hole, and further, a portion of the oil dropping passage upstream of the balance shaft housing is communicated with the oil chamber. Of oil drop passage in