internal combustion engine

Abstract

To suppress occurrence of fretting between an inner peripheral surface of a valve arm shaft insertion hole and an outer peripheral surface of a valve arm shaft in a valve arm support.SOLUTION: A valve arm shaft 14 inserted into a valve arm shaft insertion hole 13a provided in a valve arm support 13 comprises a lubricant path 14b and a valve arm support lubricant hole 14e. The valve arm support lubricant hole 14e is opened toward the inner peripheral surface of the valve arm shaft insertion hole 13a of the valve arm support 13.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to an internal combustion engine, and more particularly to a measure for suppressing the occurrence of fretting in a valve train of an internal combustion engine. [Background technology]

[0002] As disclosed in Patent Document 1, a conventional valve train configuration for an internal combustion engine is known in which a valve arm is swingably supported on a valve arm shaft. An example of an internal combustion engine equipped with such a valve train is an OHV (Over Head Valve) type. Specifically, this type of valve train configuration includes a plurality of valve arm supports arranged in the cylinder row direction, each fixed to the top of the cylinder head by means of bolts or the like, and a valve arm shaft is inserted into a valve arm shaft insertion hole provided in each of the valve arm supports. Both ends of the valve arm shaft are prevented from rotating by bolts (for example, bolted to the valve arm supports located at both ends in the cylinder row direction).

[0003] Between adjacent valve arm supports, valve arms (intake and exhaust valve arms) are supported by valve arm shafts at positions corresponding to each cylinder so as to be able to swing freely. In an OHV internal combustion engine, one end of the valve arm is connected to the tip of a push rod that reciprocates with power from the crankshaft, and the other end of the valve arm is connected to a valve (intake valve or exhaust valve). The valve opens and closes (opens and closes the intake port or exhaust port) as the valve arm swings in response to the reciprocating movement of the push rod. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-221083 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-described valve train, during assembly, it is necessary to insert the arm shaft into the arm shaft insertion hole provided in the arm support. To facilitate this operation, the inner diameter of the arm shaft insertion hole in the arm support is set slightly larger than the outer diameter of the arm shaft. Therefore, when the arm shaft is inserted into the arm shaft insertion hole in the arm support, a slight clearance exists between the inner peripheral surface of the arm shaft insertion hole and the outer peripheral surface of the arm shaft.

[0006] Therefore, if the arm shaft is bent due to the swing of the arm caused by the reciprocating movement of the push rod, the arm shaft will move slightly inside the arm shaft insertion hole of the arm support (slight movement due to the existence of the clearance mentioned above), and there is a risk of fretting (surface damage) occurring due to the reciprocating sliding between the inner surface of the arm shaft insertion hole of the arm support and the outer surface of the arm shaft. This fretting is undesirable because it can cause abnormal noise and deterioration of durability.

[0007] The present invention has been made in consideration of these points, and its purpose is to suppress the occurrence of fretting between the inner surface of the arm shaft insertion hole of the arm support and the outer surface of the arm shaft. [Means for solving the problem]

[0008] The solution of the present invention to achieve the above object is a valve arm support supported by a cylinder head, The aforementioned a valve arm shaft inserted into a valve arm shaft insertion hole provided in the valve arm support; The aforementioned The present invention is based on an internal combustion engine having a valve arm supported on a valve arm shaft so as to be able to swing freely. The internal combustion engine has a valve arm shaft provided with a lubricating oil path and The aforementioned An oil feed hole communicating with a lubricating oil path is provided. The oil feed hole is provided at a position corresponding to the valve arm support, and a valve for opening and closing an intake port or an exhaust port is connected to one end of the valve arm. The opening position of the oil feed hole toward the inner circumferential surface of the valve arm shaft insertion hole of the valve arm support is The oil supply hole is formed as a lubricating oil passage that is inclined upward from the position where it communicates with the lubricating oil path toward the valve arrangement position, so that the oil supply hole is inclined upward from the position where it communicates with the lubricating oil path toward the valve arrangement position,The valve is characterized in that it is set at a position closer to the valve installation position.

[0009] With this feature, the lubricating oil flowing through the lubricating oil path provided in the arm shaft reaches the oil feed hole via this lubricating oil path. Since this oil feed hole is provided at a position corresponding to the arm support, the lubricating oil flowing out of this oil feed hole lubricates the inner circumferential surface of the arm shaft insertion hole of the arm support. In other words, even if the arm shaft moves slightly inside the arm shaft insertion hole of the arm support, the lubricating oil flows into the clearance between the inner circumferential surface of the arm shaft insertion hole of the arm support and the outer circumferential surface of the arm shaft, thereby lubricating the gap between the inner circumferential surface of the arm shaft insertion hole of the arm support and the outer circumferential surface of the arm shaft, thereby suppressing the occurrence of fretting.

[0011] especially, To effectively suppress the occurrence of fretting, it is preferable to supply lubricating oil toward a position on the inner circumferential surface of the arm shaft insertion hole of the arm support where fretting is particularly likely to occur. When the arm swings while supported by the arm shaft, when the arm biases the valve toward the open side, the arm receives a force in the opposite direction to the movement of the valve. This force is transmitted from the arm to the arm shaft, and the arm shaft is pressed against the valve side (the side closer to the valve installation position) of the inner circumferential surface of the arm shaft insertion hole of the arm support. Therefore, fretting is likely to occur at this position. In this solution, an oil supply hole is provided at the valve side position, where fretting is likely to occur, so this area can be well lubricated and fretting can be effectively suppressed.

[0012] In addition, the internal lubricating oil passage provided in the cylinder head, the internal lubricating oil passage provided in the valve arm support, the lubricating oil inlet hole provided in the valve arm shaft, and the lubricating oil passage are connected to each other.

[0013] According to this, the lubricating oil flows along the internal lubricating oil passage in the cylinder head, the internal lubricating oil passage in the cylinder support, the lubricating oil inlet hole and the lubricating oil passage in the cylinder shaft, and is supplied from this lubricating oil passage through the oil feed hole to the inner circumferential surface of the cylinder shaft insertion hole in the cylinder support. Therefore, it is possible to efficiently supply the lubricating oil to the inner circumferential surface of the cylinder shaft insertion hole without requiring special piping (external piping) to supply the lubricating oil to the inner circumferential surface of the cylinder shaft insertion hole in the cylinder support. This reduces the number of parts and simplifies the assembly process of the internal combustion engine.

[0014] A plurality of the valve arm supports are arranged in the cylinder row direction, and the in-support lubricating oil path is provided in any one of the plurality of valve arm supports.

[0015] This simplifies the processing of the lubricating oil passages within the head and the support, compared to when an internal lubricating oil passage is provided in each of multiple valve arm supports, thereby reducing processing costs.

[0016] The valve arm support also has a plurality of fixed portions that are fixed to the cylinder head, and the support internal lubricating oil path is offset from a center line connecting the plurality of fixed portions.

[0017] This makes it possible to ensure a sufficient area for forming the lubricating oil path within the support. [Effects of the Invention]

[0018] In the present invention, the arm shaft inserted into the arm shaft insertion hole provided in the arm support is provided with a lubricating oil path and an oil feed hole, and this oil feed hole is provided at a position corresponding to the arm support. Therefore, lubricating oil can be supplied to the clearance between the inner peripheral surface of the arm shaft insertion hole of the arm support and the outer peripheral surface of the arm shaft, and even if the arm shaft moves slightly inside the arm shaft insertion hole of the arm support, the inner peripheral surface of the arm shaft insertion hole of the arm support and the outer peripheral surface of the arm shaft are lubricated, thereby suppressing the occurrence of fretting. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a cross-sectional view of an internal combustion engine according to an embodiment. [Figure 2] FIG. 1 is a perspective view showing a part of a valve train of an internal combustion engine. [Figure 3] FIG. 3 is a perspective view showing a cross section taken along line III-III in FIG. 2. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Figure 5] FIG. [Figure 6] FIG. 1 is a cross-sectional view of the valve arm shaft. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. [Figure 8] FIG. 2 is a bottom view showing a valve train of the internal combustion engine. [Figure 9] FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. [Figure 10] FIG. 4 is a cross-sectional view taken along line XX in FIG. [Figure 11] FIG. 2 is a conceptual diagram illustrating a supply path of lubricating oil to a valve train. DETAILED DESCRIPTION OF THE INVENTION

[0020] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with reference to the drawings. In this embodiment, the present invention is applied to an in-line four-cylinder OHV internal combustion engine (diesel engine).

[0021] -General configuration of an internal combustion engine- Before describing the lubrication structure of the valve train, which is a feature of this embodiment, the general configuration of the internal combustion engine according to this embodiment will be described.

[0022] FIG. 1 is a cross-sectional view of an internal combustion engine 1 according to this embodiment. The internal combustion engine 1 according to this embodiment is an in-line four-cylinder OHV type, and FIG. 1 shows a cross-section of one cylinder. The following description focuses on one cylinder, but the other cylinders have the same configuration. Note that the number of cylinders, cylinder arrangement, etc. of the internal combustion engine 1 according to the present invention are not limited to those of this embodiment.

[0023] As shown in FIG. 1, the internal combustion engine 1 according to this embodiment has an internal combustion engine main body 2 formed by attaching a cylinder head 4 to the upper side of a cylinder block 3, and an oil pan 5 for storing lubricating oil attached to the lower side of this internal combustion engine main body 2 (below the cylinder block 3).

[0024] A crankshaft 7 extending horizontally along the row of cylinders is supported at the bottom of the cylinder block 3. A cylinder 10 is formed at the top (on the cylinder head 4 side) of the cylinder block 3, and a piston 8 is fitted into the cylinder 10 so that it can slide up and down. The piston 8 is connected to the crankshaft 7 via a connecting rod 9, and the piston 8 reciprocates up and down as the air-fuel mixture is burned in the combustion chamber 6, thereby driving the crankshaft 7 to rotate.

[0025] A bonnet (valve arm case) 11 is attached to the upper side of the cylinder head 4, and the interior of the bonnet 11 serves as a valve arm chamber 12. A valve train is housed in this valve arm chamber 12. The configuration of this valve train will be described later.

[0026] The tip (lower end) of a fuel injection valve 18 (shown by a phantom line in FIG. 1) that penetrates the cylinder head 4 in the vertical direction faces the combustion chamber 6 formed by the lower surface of the cylinder head 4, the cylinder 10, and the piston 8.

[0027] In addition, an intake manifold 19 and an exhaust manifold 20 are connected to the side of the cylinder head 4, and air is supplied into the cylinder by opening the intake valve 15c, and exhaust gas is discharged from the cylinder by opening the exhaust valve (not shown in Figure 1).

[0028] A fuel injection pump 22 is disposed on the side of the cylinder block 3, and fuel stored in a fuel tank (not shown) is pressurized by the fuel injection pump 22 and supplied to the fuel injection valve 18.

[0029] A lubricating oil pump 23 is disposed below the fuel injection pump 22, and pumps up the lubricating oil stored in the oil pan 5 and supplies it to various parts via oil passages (not shown) in the cylinder block 3, thereby circulating the lubricating oil to lubricate the inside of the internal combustion engine 1.

[0030] A starter motor 24 is disposed on the opposite side of the cylinder block 3 .

[0031] -Valve train configuration- Next, the configuration of the valve train of the internal combustion engine 1 according to this embodiment will be described.

[0032] Fig. 2 is a perspective view showing a part of a valve train of the internal combustion engine 1. Fig. 3 is a perspective view showing a cross section taken along line III-III in Fig. 2. Fig. 4 is a cross section taken along line IV-IV in Fig. 3. Fig. 5 is a perspective view showing a valve arm shaft 14.

[0033] As shown in these figures, the valve train includes valve arm supports 13, 13, 13 fixed to the top of the cylinder head 4 by bolts, a valve arm shaft 14 inserted through the valve arm support 13, intake side valve arms 15, 15, ... and exhaust side valve arms 16, 16, ... supported by the valve arm shaft 14 so as to be able to swing freely.

[0034] 3 and 4, rib-like support portions 4a, 4a, 4a are provided on the top of the cylinder head 4 between the cylinders, and valve arm supports 13, 13, 13 are bolted to the upper surfaces of these support portions 4a, 4a, 4a. In addition, side supports 17, 17 (see FIG. 8, a bottom view showing the valve system) are bolted to the upper surfaces of the vertical walls on both sides of the cylinder head 4 in the direction of the cylinder row.

[0035] 4, the arm support 13 includes a support body 13b having an arm shaft insertion hole 13a through which the arm shaft 14 is inserted, a first support leg (a fixed part in the present invention) 13c extending from the support body 13b in the cylinder direction (to the right in FIG. 4), and a second support leg (a fixed part in the present invention) 13d located in the opposite direction from the support body 13b in the cylinder direction (to the left in FIG. 4). The first support leg 13c and the second support leg 13d each have bolt insertion holes 13e, 13f extending vertically. Bolts B1, B2 are inserted into the bolt insertion holes 13e, 13f from above, and the bolts B1, B2 are screwed into female threaded holes 4c, 4d formed in the support portion 4a of the cylinder head 4, thereby supporting the arm supports 13, 13, 13 on the support portions 4a, 4a, 4a, respectively.

[0036] Furthermore, a portion of the support body 13b and the first support leg 13c of the arm support 13 is recessed from the upper surface of the support portion 4a of the cylinder head 4 (recessed portion 13B recessed upward), and in this portion, a space S1 exists between the arm support 13 and the cylinder head 4. The heads of the head bolts B3 for fastening the cylinder head 4 to the cylinder block 3 are located in this space S1. In other words, before the arm support 13 is bolted to the cylinder head 4, the cylinder head 4 is fastened to the cylinder block 3 with the head bolts B3, and then the arm support 13 is abutted against the support portion 4a of the cylinder head 4 and the first support leg 13c and second support leg 13d of the arm support 13 are bolted to the support portion 4a, so that the heads of the head bolts B3 are located in the space S1.

[0037] As shown in FIG. 8, the side support 17, like the arm support 13, also has an arm shaft insertion hole (not shown), a support main body 17b, a first support leg 17c, and a second support leg 17d, and the first support leg 17c and the second support leg 17d are fastened to the upper surface of the vertical wall of the cylinder head 4 by bolts.

[0038] When the arm supports 13, 13, 13 and the side supports 17, 17 are fixed to the cylinder head 4 as described above, the arm shaft insertion holes 13a, 13a, 13a of the arm supports 13, 13, 13 and the arm shaft insertion holes of the side supports 17, 17 are arranged on the same axis, and the arm shaft 14 is inserted through these arm shaft insertion holes 13a, 13a, 13a.

[0039] As shown in Figure 5, bolt insertion holes 14a, 14a are formed at both ends of the arm shaft 14, and bolts are inserted into the bolt insertion holes 14a, 14a of the arm shaft 14 while they are aligned with bolt insertion holes (not shown) formed in the support body portion 17b of the side support 17, so that the arm shaft 14 is supported by the side supports 17 in a non-rotating state.

[0040] The arm shaft 14 is made of a cylindrical rod material. A lubricating oil passage 14b (see Figures 3 and 4) for flowing lubricating oil is formed inside the arm shaft 14, penetrating from one end to the other in the direction along the axis of the arm shaft 14. Sealing members are press-fitted into both ends of the lubricating oil passage 14b, thereby sealing both ends of the lubricating oil passage 14b.

[0041] The outer diameter of the arm shaft 14 is set slightly smaller than the inner diameter of the arm shaft insertion hole 13a of the arm support 13. In other words, the inner diameter of the arm shaft insertion hole 13a of the arm support 13 is set slightly larger than the outer diameter of the arm shaft 14. This is to facilitate the operation of inserting the arm shaft 14 into the arm shaft insertion hole 13a provided in the arm support 13 when assembling the valve train. Because the inner diameter of the arm shaft insertion hole 13a of the arm support 13 is set slightly larger than the outer diameter of the arm shaft 14, when the arm shaft 14 is inserted into the arm shaft insertion hole 13a of the arm support 13, a slight clearance exists between the inner peripheral surface of the arm shaft insertion hole 13a and the outer peripheral surface of the arm shaft 14.

[0042] 2 and 3, the intake side arm 15 and the exhaust side arm 16 are swingably supported on the arm shaft 14 at positions corresponding to each cylinder of the internal combustion engine 1, between adjacent arm supports 13, 13, and between adjacent arm supports 13 and side supports 17. That is, one intake side arm 15 and one exhaust side arm 16 are disposed between adjacent arm supports 13, 13, and between adjacent arm supports 13 and side supports 17, and are swingably supported on the arm shaft 14. Specifically, each arm 15, 16 is also formed with an arm shaft insertion hole 15a (see FIG. 9) similar to the arm support 13, and the arm shaft 14 is inserted into this arm shaft insertion hole 15a, so that each arm 15, 16 is swingably supported on the arm shaft 14.

[0043] The upper ends of a pair of intake valves 15c, 15c are connected to the end of the intake-side valve arm 15 in the cylinder direction (rightward in FIGS. 4 and 9) via a connecting member 15b. Meanwhile, the upper ends of a pair of exhaust valves (not shown) are connected to the end of the exhaust-side valve arm 16 in the cylinder direction (rightward in FIGS. 4 and 9) via a connecting member 16b (see FIG. 2). The upper ends of push rods 28 are connected to the ends of each valve arm 15, 16 in the opposite direction from the cylinder direction (leftward in FIG. 4). As shown in FIG. 1, the lower end of the push rod 28 abuts against a cam 29a on a camshaft 29 that rotates with the rotation of the crankshaft 7. The rotation of the cam 29a causes the push rod 28 to reciprocate approximately up and down. Valve springs 15d, 16d are disposed around the valve stems of the valves 15c between the connecting members 15b, 16b and the cylinder head 4. As a result, when each valve arm 15, 16 is pushed by the push rod 28, it rotates around the valve arm shaft 14, pushing the intake valve 15c or the exhaust valve downward against the biasing force of the valve springs 15d, 16d, thereby opening the intake port (opening during the intake stroke) or the exhaust port (opening during the exhaust stroke), and when the pressing force from the push rod 28 is released, the biasing force of the valve springs 15d, 16d causes the intake valve 15c or the exhaust valve to move upward, thereby closing the intake port or the exhaust port.

[0044] -Lubrication structure of valve train- Next, the lubrication structure of the valve train, which is a feature of this embodiment, will be described. Fig. 6 is a cross-sectional view of the valve arm shaft 14. Fig. 7 is a cross-sectional view taken along line VII-VII in Fig. 3. Fig. 8 is a bottom view showing the valve train of the internal combustion engine 1. Fig. 9 is a cross-sectional view taken along line IX-IX in Fig. 3. Fig. 10 is a cross-sectional view taken along line XX in Fig. 3.

[0045] 5 and 6, the arm shaft 14 is provided with a lubricating oil introduction hole 14c, arm oil supply holes 14d, 14d, ..., and arm support oil supply holes (oil supply holes in the present invention) 14e, 14e, 14e as holes communicating with the above-mentioned lubricating oil path 14b. These holes 14c, 14d, 14d, ..., 14e, 14e, 14e extend along the radial direction of the arm shaft 14, with their inner ends opening to the lubricating oil path 14b and their outer ends opening to the outer surface of the arm shaft 14. The positions of these holes 14c, 14d, 14d, ..., 14e, 14e, 14e will be described later.

[0046] As shown in Figure 7, an in-support lubricating oil passage 13g extending in the vertical direction is provided inside the second support leg 13d of the valve arm support 13. Meanwhile, an in-head lubricating oil passage 4e is formed inside the cylinder head 4, which is connected to the in-block lubricating oil passage 3a (see Figure 11) formed in the cylinder block 3. Specifically, the in-head lubricating oil passage 4e extending in the vertical direction is formed in the support support portion 4a, which is located between the first and second cylinders, of the multiple support support portions 4a, 4a, 4a provided in the cylinder head 4. Also, as shown in Figure 8 (a bottom view showing the valve system), the in-support lubricating oil passage 13g is formed in the valve arm support 13A, which is located between the first and second cylinders, of the multiple valve arm supports 13, 13, 13. The second support leg 13d of the arm support 13A has an extension 13h extending downward toward the axis of the arm shaft 14, and the in-support lubricating oil passage 13g is formed to extend vertically within the extension 13h of the second support leg 13d. As a result, the in-support lubricating oil passage 13g is disposed at a position offset from the center line L (shown by a dashed line in FIG. 8) connecting the first support leg 13c and the second support leg 13d, ensuring a sufficient area for forming the in-support lubricating oil passage 13g. As shown in FIG. 7, the upper end opening of the in-head lubricating oil passage 4e and the lower end opening of the in-support lubricating oil passage 13g are aligned. In other words, when the valve arm support 13 is fastened to the upper surface of the support support portion 4a, the upper end opening of the in-head lubricating oil passage 4e and the lower end opening of the in-support lubricating oil passage 13g of the valve arm support 13 are connected, and the lubricating oil that has flowed through the in-head lubricating oil passage 4e flows into the in-support lubricating oil passage 13g. Note that, although the in-head lubricating oil passage 4e and the in-support lubricating oil passage 13g are connected between the first and second cylinders in this example, the in-head lubricating oil passage 4e and the in-support lubricating oil passage 13g may be connected between the other cylinders.

[0047] 7, the upper end opening of the in-support lubricating oil passage 13g of the arm support 13 is aligned with the lower end opening of the lubricating oil introduction hole 14c of the arm shaft 14. In other words, when the arm shaft 14 is inserted into the arm shaft insertion hole 13a of the arm support 13, the upper end opening of the in-support lubricating oil passage 13g of the arm support 13 is connected to the lower end opening of the lubricating oil introduction hole 14c of the arm shaft 14, and the lubricating oil that has flowed through the in-support lubricating oil passage 13g flows into the lubricating oil passage 14b via the lubricating oil introduction hole 14c. In FIGS. 5 and 6, the flow of lubricating oil flowing from the lubricating oil introduction hole 14c toward the lubricating oil passage 14b is indicated by solid arrows.

[0048] The arm oil feed holes 14d formed in the arm shaft 14 supply oil toward the arm shaft insertion holes 15a of the arms 15, 16, and their outer ends (openings on the outer surface of the arm shaft 14) open toward the arm shaft insertion holes 15a of the arms 15, 16. Specifically, as shown in Figures 5, 6, and 9, two arm oil feed holes 14d are provided for each arm 15 (16). That is, an upper arm oil feed hole 14d-1 (see Figure 9) extends upward from the lubricating oil path 14b, and a lower arm oil feed hole 14d-2 extends downward from the lubricating oil path 14b. Therefore, the lubricating oil flowing through the lubricating oil path 14b is diverted to the upper arm oil feed hole 14d-1 and the lower arm oil feed hole 14d-2 and supplied between the inner circumferential surface of the arm shaft insertion hole 15a of the arm 15 (16) and the outer circumferential surface of the arm shaft 14, lubricating the space between them. This allows the arms 15, 16 supported by the arm shaft 14 to swing smoothly. In Figures 5 and 6, the flow of lubricating oil from the arm oil feed hole 14d toward the inner circumferential surface of the arm shaft insertion hole 15a is indicated by dashed arrows.

[0049] Furthermore, lubricating oil passages 15e and 15f are provided inside the arm 15 (16). Specifically, as shown in FIG. 9, a first lubricating oil passage 15e extends in the arm 15 toward the cylinder direction (to the right in FIG. 9), and a second lubricating oil passage 15f extends in the arm 15 on the opposite side to the cylinder direction (to the left in FIG. 9). The first lubricating oil passage 15e supplies lubricating oil supplied between the inner circumferential surface of the arm shaft insertion hole 15a of the arm 15 and the outer circumferential surface of the arm shaft 14 toward the connecting portion between the arm 15 and the connecting member 15b. The second lubricating oil passage 15f supplies lubricating oil supplied between the inner circumferential surface of the arm shaft insertion hole 15a of the arm 15 and the outer circumferential surface of the arm shaft 14 toward the connecting portion between the arm 15 and the push rod 28.

[0050] The arm support oil feed hole 14e formed in the arm shaft 14 supplies oil toward the arm shaft insertion holes 13a, 13a, 13a of each arm support 13, 13, 13, and as shown in Figure 10, its outer end (the opening on the outer surface of the arm shaft 14) opens toward the arm shaft insertion hole 13a of the arm support 13 (at a position corresponding to the arm support 13). Therefore, the lubricating oil that flows through the arm support oil feed hole 14e via this lubricating oil path 14b is supplied between the inner circumferential surface of the arm shaft insertion hole 13a of the arm support 13 and the outer circumferential surface of the arm shaft 14, lubricating these two surfaces. In Figures 5 and 6, the flow of lubricating oil from the arm support oil feed hole 14e toward the inner circumferential surface of the arm shaft insertion hole 13a is indicated by a dashed arrow.

[0051] 10, the opening position of the arm support oil feed hole 14e toward the inner circumferential surface of the arm shaft insertion hole 13a of the arm support 13 is set at a position (valve side) on the inner circumferential surface of the arm shaft insertion hole 13a closer to the position where the valve 15c is disposed. In other words, the arm support oil feed hole 14e is formed as a lubricating oil passage that is slightly inclined upward toward the position where the valve 15c is disposed.

[0052] Figure 11 is a conceptual diagram illustrating the lubricating oil supply path to the valve train. As shown in Figure 11, the lubricating oil flows from the in-block lubricating oil path (main gallery) 3a of the cylinder block 3 through the in-head lubricating oil path 4e of the cylinder head 4 and the in-support lubricating oil path 13g of the arm support 13, and then flows into the lubricating oil path 14b through the lubricating oil inlet hole 14c of the arm shaft 14. The lubricating oil flowing through the lubricating oil path 14b is then diverted to the arm oil feed hole 14d and the arm support oil feed hole 14e, and the lubricating oil flowing through the arm oil feed hole 14d is supplied between the inner circumferential surface of the arm shaft insertion hole 15a of each arm 15, 16 and the outer circumferential surface of the arm shaft 14, lubricating these two surfaces. On the other hand, the lubricating oil flowing through the arm support oil supply hole 14e is supplied between the inner surfaces of the arm shaft insertion holes 13a, 13a, 13a of each arm support 13, 13, 13 and the outer surface of the arm shaft 14, thereby lubricating the space between them.

[0053] In the prior art, when the arm shaft is bent due to the swing of the arm caused by the reciprocating movement of the push rod, the arm shaft moves slightly inside the arm shaft insertion hole of the arm support (slight movement due to the existence of the clearance mentioned above), and there is a risk of fretting occurring due to reciprocating sliding between the inner surface of the arm shaft insertion hole of the arm support and the outer surface of the arm shaft.

[0054] In contrast to this, in this embodiment, as described above, lubricating oil can be supplied to the clearance between the inner peripheral surfaces of the arm shaft insertion holes 13a, 13a, 13a of each arm support 13, 13, 13 and the outer peripheral surface of the arm shaft 14, and even if the arm shaft 14 moves slightly inside the arm shaft insertion hole 13a of the arm support 13, the occurrence of fretting can be suppressed by lubricating the gap between the inner peripheral surfaces of the arm shaft insertion holes 13a of the arm supports 13 and the outer peripheral surface of the arm shaft 14.

[0055] As described above, the opening position of the arm support oil supply hole 14e toward the inner circumferential surface of the arm shaft insertion hole 13a of the arm support 13 is set at a position on the inner circumferential surface of the arm shaft insertion hole 13a closer to the position where the valve 15c is disposed (see Figure 10). In order to effectively suppress the occurrence of fretting, it is preferable to supply lubricating oil toward a position on the inner circumferential surface of the arm shaft insertion hole 13a of the arm support 13 where fretting is particularly likely to occur. When the arms 15, 16 swing while supported by the arm shaft 14, when the arms 15, 16 bias the valve 15c toward the open side, the arms 15, 16 receive a force in the opposite direction to the movement of the valve 15c. This force is transmitted from the arms 15, 16 to the arm shaft 14, which presses the arm shaft 14 against a position on the inner circumferential surface of the arm shaft insertion hole 13a of the arm support 13, closer to the position where the valve 15c is located. Therefore, fretting is likely to occur at this position. In this embodiment, the arm support oil supply hole 14e is opened toward a position on the inner circumferential surface of the arm shaft insertion hole 13a of the arm support 13, closer to the position where the valve 15c is located, where fretting is likely to occur. This allows for good lubrication of this area, effectively suppressing the occurrence of fretting.

[0056] In this embodiment, the in-head lubricating oil passage 4e provided in the cylinder head 4, the in-support lubricating oil passage 13g provided in the arm support 13, and the lubricating oil inlet hole 14c, lubricating oil passage 14b, and arm support oil supply hole 14e provided in the arm shaft 14 are configured to be in communication with each other. Therefore, no special piping (external piping) is required to supply lubricating oil to the inner surface of the arm shaft insertion hole 13a of the arm support 13, and lubricating oil can be efficiently supplied to the inner surface of the arm shaft insertion hole 13a. This reduces the number of parts and simplifies the assembly work of the internal combustion engine 1.

[0057] In addition, in this embodiment, the in-support lubricating oil passage 13g is provided in one arm support 13A among the multiple arm supports 13, 13, 13. Therefore, compared to when the in-support lubricating oil passage 13g is provided in each of the multiple arm supports 13, 13, 13, the processing of the in-head lubricating oil passage 4e and the in-support lubricating oil passage 13g can be simplified, and processing costs can be reduced.

[0058] Furthermore, in this embodiment, the area between the support legs 13c, 13d of the valve arm support 13 is set back from the cylinder head 4, and the head bolt B3 is inserted from the space S1 between the setback portion 13B of the valve arm support 13 and the cylinder head 4 through the cylinder head 4 and the cylinder block 3. This allows the position of the head bolt B3 and the position of the valve arm support 13 to overlap in a plan view, making it possible to compactly realize a configuration for fixing the cylinder head 4 to the cylinder block 3 and a configuration for ensuring a lubricating oil path from the in-head lubricating oil path 4e to the in-support lubricating oil path 13g.

[0059] -Other embodiments- The present invention is not limited to the above-described embodiments, and all modifications and applications that fall within the scope of the claims and equivalents thereto are possible.

[0060] For example, in the above embodiment, the present invention is described as being applied to a push rod type OHV internal combustion engine, but the present invention can also be applied to a finger follower type OHC (Over Head Camshaft) internal combustion engine. [Industrial Applicability]

[0061] The present invention is applicable to an internal combustion engine having a valve arm support supported by a cylinder head, a valve arm shaft inserted into a valve arm shaft insertion hole of the valve arm support, and a valve arm supported by the valve arm shaft so as to be able to swing freely. [Explanation of symbols]

[0062] 1. Internal combustion engine 4 Cylinder head 4e Lubricating oil path inside the head 13 Ben'u Support 13a Arm shaft insertion hole 13c 1st support leg (fixed part) 13d 2nd support leg (fixed part) 13g Lubricant path inside support 14 Ben'u Axis 14b Lubricant path 14c Lubricating oil introduction hole 14e Valve arm support oil hole (oil hole) 15 Intake valve arm 15c intake valve 16 Exhaust valve arm L center line

Claims

1. An internal combustion engine including a valve arm support supported by a cylinder head, a valve arm shaft inserted into a valve arm shaft insertion hole provided in the valve arm support, and a valve arm supported by the valve arm shaft so as to be swingable, The arm shaft is provided with a lubricating oil passage and an oil supply hole communicating with the lubricating oil passage, The oil supply hole is provided at a position corresponding to the valve arm support, A valve for opening and closing an intake port or an exhaust port is connected to one end of the valve arm, An internal combustion engine characterized in that the opening position of the oil feed hole toward the inner surface of the valve arm shaft insertion hole of the valve arm support is set at a position closer to the valve arrangement position with respect to a vertical line passing through the center of the valve arm shaft, because the oil feed hole is formed as a lubricating oil passage that is inclined upward from the position where it communicates with the lubricating oil path toward the valve arrangement position.

2. 2. The internal combustion engine according to claim 1, An internal combustion engine characterized in that an in-head lubricating oil passage provided in the cylinder head, an in-support lubricating oil passage provided in the valve arm support, a lubricating oil inlet hole provided in the valve arm shaft, and the lubricating oil passage are connected to each other.

3. 3. The internal combustion engine according to claim 2, A plurality of the valve arm supports are arranged in the cylinder row direction, An internal combustion engine characterized in that the support internal lubricating oil path is provided in any one of the plurality of valve arm supports.

4. 4. The internal combustion engine according to claim 2 or 3, the valve arm support has a plurality of fixing portions fixed to the cylinder head, The internal combustion engine, characterized in that the support internal lubricating oil path is offset with respect to a center line connecting the plurality of fixed portions.

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