Lubrication structure of an internal combustion engine

Abstract

The present invention provides a lubrication structure for an internal combustion engine that ensures the supply of lubricating oil to the valve train sliding members and suppresses the progression of wear as much as possible. [Solution] A lubrication structure 1 for an internal combustion engine comprising a camshaft 4 supported by a camshaft housing 5 and a cam cap 6, a valve member 8 having a valve guide 10 that supports a valve 9 that opens and closes when pressed by a cam portion 4', lubricating oil 3 supplied to the valve member 8, and an oil pump for supplying the lubricating oil 3, wherein an oil passage for supplying the lubricating oil 3 to the valve guide 10 by the oil pump is formed in at least one of the camshaft housing 5 and the cam cap 6, and at least one outlet portion 18 of the oil passage is formed in the side portion 19 parallel to the central axis of the cylinder on at least one of the camshaft housing 5 and the cam cap 6, and the lubricating oil 3 that is scattered from the outlet portion 18 is supplied toward the valve guide 10 so that it is scattered downward below the cam portion 4'.

Description

Technical Field

[0001] This invention relates to a structure for lubricating the interior of a cylinder head that supports a camshaft in an internal combustion engine with lubricating oil.

Background Art

[0002] Patent Document 1 describes a valve operating camshaft lubrication device for an internal combustion engine configured to provide a lubricating oil passage in a head cover that covers the upper surface of an upper cylinder head in an engine body and supply oil from the discharge port of the passage. In this lubrication device, by opening a part of the lubricating oil passage formed in the head cover above the sliding part between the camshaft and the rocker arm and providing a discharge port, it is said that the lubricity of the sliding part can be improved.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, by opening the discharge port of the lubricating oil passage inside the cylinder head cover above the camshaft and dripping the lubricating oil from above the camshaft, lubricating oil can be supplied to the sliding parts including the camshaft. However, in the configuration of the lubrication device described in Patent Document 1, it may be difficult to supply oil to the valve operating sliding member.

[0005] For example, in a camshaft configuration where the discharge port is located vertically above the cam section, any oil that is discharged will primarily be supplied to the cam section even if it drips. However, for sliding parts located vertically below the cam section (valve components such as valve guides and valve springs), the cam section may obstruct the supply of oil to these sliding parts, resulting in insufficient oil supply to them. Furthermore, even if the discharge port is not above the cam section, a camshaft position sensor (cam angle sensor) for detecting the rotation angle of the camshaft may be located near the cam section. In such cases, even if the oil discharge position is slightly away from the cam section and some of the dripped oil is supplied to the cam section, the oil may not reach the sliding parts below the cam section, potentially leading to increased wear or seizure of the sliding parts.

[0006] This invention was made in view of the above-mentioned technical problems, and aims to provide a lubrication structure for an internal combustion engine that can ensure the supply of lubricating oil to the valve train sliding members and suppress the progression of wear as much as possible. [Means for solving the problem]

[0007] To achieve the above objective, this invention provides a lubrication structure for an internal combustion engine comprising: a camshaft that rotates in conjunction with the output shaft of the internal combustion engine and is supported by a camshaft housing and a cam cap; a valve member having a valve guide that is positioned below the cam portion of the camshaft and supports a valve that is pressed by the cam portion to open and close; a cylinder head that houses the valve member and is fixed to the lower part of the camshaft housing and to the upper part of a cylinder block that houses a cylinder; lubricating oil supplied to the valve member; and an oil pump for supplying the lubricating oil, wherein an oil passage for supplying the lubricating oil to the valve guide by the oil pump is formed in at least one of the camshaft housing and the cam cap, and at least one outlet portion of the oil passage is formed on the side surface parallel to the central axis of the cylinder in at least one of the camshaft housing and the cam cap, and the lubricating oil is supplied toward the valve guide so that the lubricating oil scattered from the outlet portion is scattered downward below the cam portion. [Effects of the Invention]

[0008] According to the lubrication structure for an internal combustion engine of this invention, an oil passage for supplying lubricating oil is formed in at least one of the camshaft housing and the cam cap that support the camshaft, and at least one outlet for the oil passage is formed on the side surface of at least one of the camshaft housing and the cam cap parallel to the central axis of the cylinder of the internal combustion engine. Furthermore, the lubricating oil that is scattered from the outlet is supplied toward the valve guide so that it is scattered downwards from the cam section. With this configuration, even if the lubricating oil discharged from above the camshaft cannot be sufficiently supplied to the valve guide, an outlet for the oil passage is provided on at least one of the side surfaces of the camshaft housing and the cam cap so that the lubricating oil can be scattered toward the valve guide, thereby ensuring the supply of lubricating oil to the valve guide and suppressing the progression of wear as much as possible. [Brief explanation of the drawing]

[0009] [Figure 1] This is a partial view of the lubrication structure of the internal combustion engine of this invention, seen from above. [Figure 2] This is a cross-sectional view XX illustrating the operation of the lubrication structure of the internal combustion engine of this invention. [Modes for carrying out the invention]

[0010] Embodiments of this invention will be described with reference to Figures 1 and 2. Note that the embodiments described below are merely examples of how this invention can be implemented and do not limit the invention.

[0011] The lubrication structure 1 for an internal combustion engine in this invention is for supplying lubricating oil 3 to a valve train sliding member 2 in an internal combustion engine (engine) mounted on a vehicle, for example. The engine in the embodiment of this invention is, for example, an inline four-cylinder engine, the partial view shown in Figure 1 is a view of the intake side or exhaust side valve train sliding member 2 from above, and the partial cross-sectional view shown in Figure 2 is a view of the valve train sliding member 2 from the side.

[0012] Camshafts 4, which rotate in conjunction with the engine's output shaft (not shown), are arranged parallel to each other on the intake and exhaust sides. The camshafts 4 shown in Figures 1 and 2 are either intake or exhaust camshafts, with the lower side of the camshaft 4 supported by a camshaft housing 5, and the upper side of the camshaft 4 rotatably supported by a cam cap 6 fastened to the camshaft housing 5. The camshaft housing 5 is fixed to the upper part of the cylinder head 7, and the cylinder head 7 is further fixed to the upper part of a cylinder block (not shown). The cylinder head 7 houses valve members 8 equipped with intake or exhaust valves, and constitutes the ceiling of the combustion chamber of each cylinder of the engine.

[0013] As shown in Figures 1 and 2, the valve member 8 comprises a valve (valve head) 9, a valve guide 10 supporting the valve 9, a valve spring 11 and a valve stem end 12 for pressing the valve 9, a valve portion 13 positioned below the cam portion 4' of the camshaft 4, a rocker arm 14 that contacts the outer circumferential surface of the cam portion 4', and a lash adjuster 15 at one end of the rocker arm 14 that generates a reaction force to the load being pressed, on the other end opposite the pressing portion that presses the valve portion. In other words, the valve member 8 is positioned so that the rocker arm 14 contacts the outer circumferential surface of the cam portion 4' of the camshaft 4, and by being pressed and oscillating by the cam portion 4', it presses the valve stem end 12 and opens and closes the valve 9.

[0014] The valve train sliding members 2, such as the camshaft 4 and valve member 8, slide or oscillate, and lubricating oil 3 is supplied by an oil pump (not shown). For example, in the prior art configuration, where the discharge port is located vertically above the cam portion 4' of the camshaft 4, even if the discharged lubricating oil 3 drips, it is mainly supplied to the cam portion 4'. However, the valve guide 10, located vertically below the cam portion 4' in the valve member 8, particularly inside the valve spring 11, may not receive sufficient lubricating oil 3 downwards because the supply of lubricating oil 3 downwards is obstructed by the cam portion 4' and other components such as a cam angle sensor (not shown).

[0015] Therefore, in the lubrication structure 1 for the internal combustion engine of this invention, the focus is on the support member 16 of the camshaft 4, which is composed of a camshaft housing 5 and a cam cap 6. A lubrication oil passage 17 (hereinafter simply referred to as oil passage 17) is formed in the support member 16, and lubricating oil 3 is supplied to the valve guide 10 from the outlet of the oil passage 17. Specifically, an oil passage 17 through which lubricating oil 3 passes is formed inside the support member 16 (on the inside of the mating surface of the camshaft housing 5 and the cam cap 6). Furthermore, in the embodiment of this invention, the groove for the oil passage 17 is provided on the mating surface of the camshaft housing 5 and the cam cap 6, respectively, but it is not limited to this, and may be formed on at least one of the camshaft housing 5 and the cam cap 6.

[0016] As shown in Figure 1, the outlet portion 18 of the oil passage 17 is formed at least once on a side surface 19 parallel to the central axis of the cylinder housed in a cylinder block (not shown) on at least one of the camshaft housing 5 and the cam cap 6. The lubricating oil 3 that splashes from the outlet portion 18 is supplied towards the valve guide 10 of the valve member 8, where the supply of lubricating oil 3 is significant, so that it splashes downward below the cam portion 4' of the camshaft 4. In Figures 1 and 2, the direction 20 in which the lubricating oil 3 is supplied from the outlet portion 18 to the valve guide 10 is indicated by a dashed line.

[0017] According to an embodiment of this invention, an oil passage 17 for supplying lubricating oil 3 is formed in at least one of the camshaft housing 5 and cam cap 6 that support the camshaft 4, and at least one outlet portion 18 of the oil passage 17 is formed on a side surface 19 parallel to the central axis of the cylinder of the internal combustion engine on at least one of the camshaft housing 5 and cam cap 6. Furthermore, the lubricating oil 3 that is scattered from the outlet portion 18 is supplied toward the valve guide 10 so that it is scattered downwards from the cam portion 4'. With this configuration, even if the lubricating oil 3 discharged from above the camshaft 4 cannot be sufficiently supplied to the valve guide 10, the supply of lubricating oil 3 to the valve guide 10 can be ensured and the progression of wear can be suppressed as much as possible because an outlet portion 18 of the oil passage 17 is provided on at least one of the side surfaces of the camshaft housing 5 and cam cap 6, which is formed so that the lubricating oil 3 is scattered toward the valve guide 10.

[0018] The above-described embodiments are merely examples of how the present invention may be implemented and do not limit the invention. For example, the lubrication structure 1 of the internal combustion engine targeted by the present invention has only one outlet 18 of the oil passage 17, but is not limited to this, and may have multiple outlets if there are multiple areas where the supply is particularly significant. [Explanation of Symbols]

[0019] 1 Lubrication structure of internal combustion engine 2 Valve sliding member 3 Lubricating oil 4 Camshaft 4’ Cam portion 5 Camshaft housing 6 Cam cap 7 Cylinder head 8 Valve member 9 Valve head 10 Valve guide 11 Valve spring 12 Valve stem end 13 Valve portion 14 Rocker arm 15 Lash adjuster 16 Support member 17 Oil passage 18 Outlet portion 19 Side surface portion 20 Supplying direction

Claims

[Claim 1] A lubrication structure for an internal combustion engine comprising: a camshaft that rotates in conjunction with the output shaft of the internal combustion engine and is supported by a camshaft housing and a cam cap; a valve member having a valve guide that is positioned below the cam portion of the camshaft and supports a valve that is pressed by the cam portion to open and close; a cylinder head that houses the valve member and is fixed to the lower part of the camshaft housing and to the upper part of the cylinder block that houses the cylinder; lubricating oil supplied to the valve member; and an oil pump for supplying the lubricating oil, wherein An oil passage for supplying the lubricating oil to the valve guide by the oil pump is formed in at least one of the camshaft housing and the cam cap. At least one outlet for the oil passage is formed on the side surface of at least one of the camshaft housing and the cam cap, parallel to the central axis of the cylinder. The lubricating oil that is scattered from the outlet is supplied toward the valve guide so that it is scattered downwards from the cam section. A lubrication structure for an internal combustion engine characterized by the following features.

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