Internal combustion engine

Abstract

To provide a technology for preventing oil from leaking out from between a seating face of a bolt and an outside surface of a crank pulley.SOLUTION: An internal combustion engine includes: a cylinder block; a crankshaft; a sprocket fitted to one end of the crankshaft; a cover for forming a chain chamber for accommodating the sprocket and including an opening for exposing an end surface on one end of the crankshaft to the outside; a crank pulley fitted to one end of the crankshaft; and a bolt fastened to the end surface of the crankshaft and fixing the crank pulley to the crankshaft. A space surrounded by an inner peripheral surface of a boss part of the crank pulley is formed between the end surface of the crankshaft and a seating face of the bolt. An oil passage extending to the chain chamber through the boss part and a screen taking a round the inner peripheral surface on the bolt side relative to the oil passage are installed at the inner peripheral surface of the boss part of the crank pulley.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] This specification discloses an internal combustion engine. [Background technology]

[0002] The internal combustion engine described in Patent Document 1 includes a sprocket and a crank pulley attached to one end of a crankshaft, and a bolt fastened to an end face of the one end of the crankshaft to fix the crank pulley to the crankshaft. A space surrounded by the inner peripheral surface of a boss portion of the crank pulley is formed between the end face of the crankshaft and a seating surface of the bolt. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2001-090809 A Summary of the Invention [Problem to be solved by the invention]

[0004] Oil for lubricating a chain attached to the sprocket flows between the crankshaft and the sprocket, and between the crankshaft and the boss of the crank pulley. The oil that flows in can accumulate in a space surrounded by the inner peripheral surface of the boss of the crank pulley. The bolt seat abuts against the outer surface of the crank pulley, and if the surface roughness of the seat is high, the oil that accumulates in the space can seep out from between the bolt seat and the outer surface of the crank pulley. This specification provides a technique for preventing oil from seeping out from between the bolt seat and the outer surface of the crank pulley. [Means for solving the problem]

[0005] The internal combustion engine disclosed in this specification comprises a cylinder block, a crankshaft rotatably supported within the cylinder block and having one end protruding from a side surface of the cylinder block, a sprocket attached to the one end of the crankshaft on the outside of the cylinder block, a cover attached to the side surface of the cylinder block, forming a chain chamber for accommodating the sprocket and having an opening for exposing an end face at the one end of the crankshaft to the outside, a crank pulley attached to the one end of the crankshaft on the outside of the cover, and an oil seal disposed between the opening of the crankshaft and a boss portion of the crank pulley for preventing oil from leaking out from the chain chamber to the outside, and a bolt fastened to the end face of the crankshaft for fixing the crank pulley to the crankshaft, wherein a space surrounded by the inner circumferential surface of the boss portion of the crank pulley is formed between the end face of the crankshaft and a seating surface of the bolt, and the inner circumferential surface of the boss portion of the crank pulley is provided with an oil passage passing through the boss portion to extend into the chain chamber, and a partition encircling the inner circumferential surface on the bolt side of the oil passage.

[0006] According to the above configuration, the oil is blocked by the partition and is prevented from reaching the gap between the bolt seat and the outer surface of the crank pulley. Furthermore, the oil that accumulates between the partition and the end face of the crankshaft flows through the oil passage to the chain chamber. Oil is prevented from accumulating in the space surrounded by the inner peripheral surface of the boss portion of the crank pulley, and as a result, oil is prevented from seeping out from between the bolt seat and the outer surface of the crank pulley.

[0007] Details and further improvements of the technology disclosed in this specification are described in the following "Forms for Carrying Out the Invention". [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a conceptual diagram of an internal combustion engine. [Diagram 2] This is an enlarged view of area II. [Diagram 3] FIG. 13 is a diagram showing how oil flows. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] (Configuration of the internal combustion engine 2; Figs. 1 and 2) The internal combustion engine 2 includes a cylinder block 10, a cylinder head 12, a crankshaft 14, a sprocket 16, a cover 18, a crank pulley 20, an oil seal 22, and a bolt 24.

[0010] The cylinder block 10 supports a crankshaft 14 so that the crankshaft 14 is rotatable within the cylinder block 10. An opening at the top of the cylinder block 10 is covered by a cylinder head 12. One end of the crankshaft 14 protrudes from a side surface 10a of the cylinder block 10.

[0011] The sprocket 16 is attached to one end of the crankshaft 14, outside the cylinder block 10. A chain (not shown) is attached to the sprocket 16. A key groove is formed on the inner peripheral surface of the sprocket 16, and the rotation of the sprocket 16 relative to the crankshaft 14 is restricted by a key 28.

[0012] The cover 18 is attached to the side surface 10a of the cylinder block 10. The cover 18 forms a chain chamber 18a that houses the sprocket 16. Oil is poured into the chain chamber 18a to lubricate the chain of the sprocket 16. The cover 18 has an opening 18b that exposes an end face 14a at one end of the crankshaft 14 to the outside.

[0013] The crank pulley 20 is attached to one end of the crankshaft 14 outside the cover 18. The crank pulley 20 has a boss portion 20a for fixing the crank pulley 20 to the crankshaft 14. The boss portion 20a passes through an opening 18b of the cover 18. A key groove is formed on the inner peripheral surface of the boss portion 20a, and a key 28 restricts the rotation of the crank pulley 20 relative to the crankshaft 14.

[0014] The oil seal 22 is provided between the opening 18b of the cover 18 and the boss portion 20a of the crank pulley 20. The oil seal 22 prevents oil from leaking out of the cover 18 from the chain chamber 18a.

[0015] The bolt 24 is fastened to the end face 14 a of the crankshaft 14 to fix the crank pulley 20 and the sprocket 16 to the crankshaft 14 .

[0016] As shown in FIG. 2, a space 30 surrounded by the inner peripheral surface 20b of the boss portion 20a of the crank pulley 20 is formed between the end face 14a of the crankshaft 14 and the seating surface 24a of the bolt 24. The arrows shown in FIG. 3 indicate oil flowing from the chain chamber 18a into the space 30. For example, there are small gaps between the sprocket 16 and the key 28, between the sprocket 16 and the boss portion 20a, and between the boss portion 20a and the key 28. The oil flows into the space 30 through these gaps and accumulates in the space 30. The seating surface 24a of the bolt 24 abuts against the outer surface of the crank pulley 20, but if the surface roughness of the seating surface 24a is large, the oil accumulated in the space 30 may seep out from between the seating surface 24a and the outer surface of the crank pulley 20.

[0017] In this embodiment, to address the above problem, an oil passage 20c and a partition 20d are provided on the inner peripheral surface 20b of the boss portion 20a. The oil passage 20c passes through the boss portion 20a and extends to the chain chamber 18a. The partition 20d runs around the inner peripheral surface 20b of the boss portion 20a on the bolt 24 side of the oil passage 20c.

[0018] 3, oil that flows into space 30 is blocked by partition 20d, preventing the oil from reaching the gap between seat surface 24a of bolt 24 and the outer surface of crank pulley 20. Meanwhile, oil accumulates in space 30 between partition 20d and end face 14a of crankshaft 14, but this oil flows through oil passage 20c to chain chamber 18a. Oil is prevented from accumulating in space 30, and as a result, oil can be prevented from seeping out from between seat surface 24a of bolt 24 and the outer surface of crank pulley 20.

[0019] (Correspondence) The internal combustion engine 2 is an example of an "internal combustion engine." The cylinder block 10, the crankshaft 14, and the sprocket 16 are examples of a "cylinder block," a "crankshaft," and a "sprocket," respectively. The cover 18, the chain chamber 18a, and the opening 18b are examples of a "cover," a "chain chamber," and a "opening," respectively. The crank pulley 20 and the boss portion 20a are examples of a "crank pulley" and a "boss portion," respectively. The oil seal 22 and the bolt 24 are examples of an "oil seal" and a "bolt," respectively. The end face 14a, the seating surface 24a, the inner peripheral surface 20b, and the space 30 are examples of an "end face," a "seating surface," an "inner peripheral surface," and a "space," respectively. The oil passage 20c and the partition 20d are examples of an "oil passage" and a "partition," respectively.

[0020] The following points should be noted regarding the techniques shown in the embodiments: A configuration having the oil passage 20c but not the partition 20d, and a configuration not having the oil passage 20c but having the partition 20d are both novel and useful. [Explanation of symbols]

[0021] 2: internal combustion engine, 10: cylinder block, 10a: side surface, 12: cylinder head, 14: crankshaft, 14a: end surface, 16: sprocket, 18: cover, 18a: chain chamber, 18b: opening, 20: crank pulley, 20a: boss portion, 20b: inner peripheral surface, 20c: oil passage, 20d: partition, 22: oil seal, 24: bolt, 24a: seat surface, 28: key, 30: space

Claims

[Claim 1] A cylinder block; a crankshaft that is rotatably supported within the cylinder block and has one end that protrudes from a side surface of the cylinder block; a sprocket attached to the one end of the crankshaft on the outside of the cylinder block; a cover attached to a side surface of the cylinder block, forming a chain chamber for accommodating the sprocket, and having an opening for exposing an end face at the one end of the crankshaft to the outside; a crank pulley attached to the one end of the crankshaft outside the cover; an oil seal provided between the opening of the cover and a boss portion of the crank pulley to prevent oil from leaking from the chain chamber to the outside; a bolt fastened to the end surface of the crankshaft and fixing the crank pulley to the crankshaft; Equipped with a space surrounded by an inner circumferential surface of the boss portion of the crank pulley is formed between the end face of the crankshaft and a seat surface of the bolt, an oil passage that passes through the boss portion and extends to the chain chamber, and a partition that surrounds the inner circumferential surface on the bolt side of the oil passage is provided on the inner circumferential surface of the boss portion of the crank pulley; Internal combustion engine.

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