Rocker shaft connection structure

Abstract

To provide a rocker shaft connection structure that can enhance position accuracy of rocker shafts in a circumferential direction, and restrain the rocker shafts from shifting in an axial direction.SOLUTION: A rocker shaft connection structure comprises a first rocker shaft, and a second rocker shaft provided on an axis of the first rocker shaft. The first rocker shaft comprises a first overlap part overlapping with the second rocker shaft when viewed from a direction intersecting with the axis. The second rocker shaft comprises a second overlap part overlapping with the first overlap part when viewed from the direction intersecting with the axis. The first overlap part and the second overlap part are connected to each other by bolts.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to a rocker shaft connection structure.

Background Art

[0002] Patent Document 1 discloses a structure in which the outer periphery of a rocker shaft is placed on a mounting seat formed on a rocker bracket of an engine. In Patent Document 1, the ends of a pair of divided rocker shafts are placed opposite to each other on the mounting seat. The ends of the pair of rocker shafts are pressed against the rocker bracket side by a cap. A semi-circular notch groove is formed on the end faces of the pair of rocker shafts. An eye bolt is inserted through the notch grooves of the cap and the pair of rocker shafts. The tip of the eye bolt is screwed into a screw hole of the rocker bracket. A lubricating oil passage of the rocker bracket is opened in the screw hole. Patent Document 2 discloses a structure including a rocker shaft divided into a plurality of parts in the axial direction and a rocker holder that fits and holds between the divided parts of the rocker shaft. In Patent Document 2, the oil passage in the rocker holder is formed by bending it downward so as to be lower than the oil passage in the rocker shaft. The end of the rocker shaft is fitted and held in a recess of the rocker holder. Patent Document 3 discloses a structure in which the rocker shaft of each cylinder is formed by dividing it into a pair of rocker shafts. In Patent Document 3, the pair of rocker shafts are respectively inserted and supported by the bearing portions of the rocker support. The rocker shafts between the cylinders adjacent to each other inside the engine among the rocker shafts of each cylinder are integrally connected. The outer end of the rocker shaft disposed outside the engine abuts against the head of the bolt that fixes the rocker support to the cylinder head. Patent Document 4 discloses a structure in which a rocker shaft is divided into at least two shaft portions. In Patent Document 4, each shaft portion is coaxially joined with a sealing member having a shape corresponding to a hydraulic supply passage interposed therebetween. The sealing member is formed in a shape that engages with a locking recess provided at an end portion on at least one side of both shaft portions sandwiching the sealing member.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the case of Patent Document 1, since the end portions of the pair of divided rocker shafts face each other in the axial direction, there is room for improvement in enhancing the circumferential position accuracy of the rocker shaft. In addition, due to the play of the eye bolt, the pair of rocker shafts may be displaced in the axial direction. In the case of Patent Document 2, since the end portion of the rocker shaft is fitted and held in the recess of the rocker holder, there is room for improvement in enhancing the circumferential position accuracy of the rocker shaft. In the case of Patent Document 3, since the outer end portion of the rocker shaft disposed outside the engine abuts against the head of the bolt, the rocker shaft may be displaced in the axial direction due to the play of the bolt. In the case of Patent Document 4, since each shaft portion is coaxially joined with a sealing member interposed therebetween, there is room for improvement in enhancing the circumferential position accuracy of the rocker shaft.

[0005] Therefore, an object of the present invention is to provide a rocker shaft connection structure that can improve the circumferential position accuracy of the rocker shaft and suppress the axial displacement of the rocker shaft.

Means for Solving the Problems

[0006] A rocker shaft connection structure according to an aspect of the present invention includes a first rocker shaft and a second rocker shaft provided on the axis of the first rocker shaft. The first rocker shaft has a first overlapping portion that overlaps the second rocker shaft when viewed in a direction intersecting the axis, and the second rocker shaft has a second overlapping portion that overlaps the first overlapping portion when viewed in a direction intersecting the axis. The first overlapping portion and the second overlapping portion are connected to each other by bolts. wherein the first rocker shaft has a first shaft body extending parallel to the axis and having a first oil passage formed therein, the second rocker shaft has a second shaft body extending parallel to the axis and having a second oil passage formed therein, the first oil passage is formed to stop before the first overlapping portion, and the second oil passage is formed to stop before the second overlapping portion .

Effects of the Invention

[0007] According to the above aspect, it is possible to improve the circumferential position accuracy of the rocker shaft and suppress the axial displacement of the rocker shaft.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the embodiment, as an example of the rocker shaft connection structure, a rocker shaft connection structure provided in a diesel engine having an OHC (Over Head Camshaft) structure will be described. For example, the diesel engine is used in various construction machines such as dump trucks, bulldozers, hydraulic excavators, wheel loaders, etc., and drive devices for large generators.

[0010] <Rocker Shaft Connection Structure> As shown in FIG. 1, the rocker shaft connection structure 10 includes a first rocker shaft 11 and a second rocker shaft 12 provided on the axis C of the first rocker shaft 11. For example, the total axial length L10 (the total length of the rocker shaft connection structure 10) of the first rocker shaft 11 and the second rocker shaft 12 is 1 m or more. For example, the total axial length L10 of the first rocker shaft 11 and the second rocker shaft 12 is set to a length of 1000 mm or more and 1070 mm or less.

[0011] Hereinafter, the axis C of the first rocker shaft 11 will also be simply referred to as the "axis C". FIG. 1 corresponds to a cross-sectional view obtained by cutting the rocker shaft connection structure 10 in a vertical plane including the axis C. The axis C extends along the front-rear direction of the diesel engine 1 (hereinafter also simply referred to as the "engine 1"). Note that the "front side of the engine 1" corresponds to the side opposite to the side where the flywheel (not shown) is provided in the engine 1, and the "rear side of the engine 1" corresponds to the side where the flywheel is provided in the engine 1, respectively.

[0012] The engine 1 includes a cylinder head 3 connected to a cylinder block 2. The cylinder head 3 stands upright vertically above the cylinder block 2. Each rocker shaft 11, 12 is connected to the upper part of the cylinder head 3 via a cap 4.

[0013] A plurality of rocker arms 5, 6 (an intake-side rocker arm 5 and an exhaust-side rocker arm 6) are rotatably supported on each rocker shaft 11, 12. Each rocker arm 5, 6 is supported on each rocker shaft 11, 12 via a bearing 7. For example, the plurality of rocker arms 5, 6 are composed of six intake-side rocker arms 5 and six exhaust-side rocker arms 6. For example, they are alternately arranged in the order of the exhaust-side rocker arm 6 and the intake-side rocker arm 5 from the front side to the rear side of the engine 1.

[0014] <The First Rocker Shaft> The first rocker shaft 11 is provided at the front part of the engine 1. The first rocker shaft 11 includes a first shaft body 20 that extends parallel to the axis C and in which a first oil passage 22 is formed, and a first overlapping part 21 that overlaps the second rocker shaft 12 when viewed in a direction intersecting the axis C. For example, the total axial length L11 of the first rocker shaft 11 (the axial length including the first shaft body 20 and the first overlapping part 21) is set to a length of 510 mm or more and 570 mm or less.

[0015] As shown in FIG. 2, the first shaft body 20 is formed in a cylindrical shape extending along the front-rear direction of the engine 1. For example, the axial length L20 of the first shaft body 20 is set to a length of 480 mm or more and 520 mm or less. For example, the diameter D20 (the maximum outer diameter) of the first shaft body 20 is set to a size of 30 mm or more and 50 mm or less.

[0016] As shown in Fig. 1, the first oil passage 22 is formed so as to stop in front of the first overlapping portion 21. The first oil passage 22 has a first axial passage 23 extending along the axial direction of the first shaft body 20 and a first radial passage 24 (see Fig. 2) connected to the first axial passage 23 and extending along the radial direction of the first shaft body 20.

[0017] The length of the first axial passage 23 in the extending direction is shorter than the axial length L20 of the first shaft body 20. For example, the diameter D23 (opening diameter) of the first axial passage 23 is set to a size of 14 mm or more and 20 mm or less. As shown in Fig. 2, the first radial passage 24 opens to the outside in the radial direction of the first shaft body 20 at positions corresponding to the respective rocker arms 5, 6 (see Fig. 1).

[0018] As shown in Fig. 1, the first shaft body 20 is connected to the upper part of the cylinder head 3 by bolts 13 via a cap 4. As shown in Fig. 2, a through hole 25 is formed in the first shaft body 20 so as to open in the vertical direction through which the bolts 13 can be inserted. The first shaft body 20 has a plurality (for example, three in this embodiment) of upper seating surfaces 26 on which the heads of the bolts 13 are seated. The plurality of upper seating surfaces 26 are arranged at intervals in the axial direction of the first shaft body 20. The plurality of upper seating surfaces 26 are formed at the upper part of the first shaft body 20. The upper seating surface 26 has a rectangular shape having a longitudinal direction in the axial direction of the first shaft body 20 and being parallel to the horizontal plane. Two through holes 25 are opened in one upper seating surface 26.

[0019] The first shaft body 20 has a plurality (for example, three in this embodiment) of lower seating surfaces 27 that contact the cap 4 (see Fig. 1). The lower seating surfaces 27 are formed at the lower part of the first shaft body 20. The lower seating surfaces 27 are arranged at positions overlapping the upper seating surfaces 26 when viewed from the vertical direction. The lower seating surface 27 has a rectangular shape having a longitudinal direction in the axial direction of the first shaft body 20 and being parallel to the horizontal plane.

[0020] In the first shaft main body 20, a relief groove 28 for avoiding a bolt 15 (see FIG. 4) for connecting a cap 4 to the upper part of the cylinder head 3 is formed. The relief groove 28 is recessed radially inward of the first shaft main body 20 at a position corresponding to one side of each seating surface 26, 27. Note that the relief groove 28 may not be formed in the first shaft main body 20. For example, the formation mode of the relief groove 28 can be changed according to the required specifications.

[0021] As shown in FIG. 2, the first overlapping portion 21 is integrally connected to the lower part of the rear end of the first shaft main body 20. The first overlapping portion 21 protrudes from the lower part of the rear surface of the first shaft main body 20 toward the rear side of the engine 1. For example, the length L21 in the protruding direction of the first overlapping portion 21 is set to a length of 30 mm or more and 50 mm or less.

[0022] The upper surface 29 (flat surface) of the first overlapping portion 21 is formed parallel to the horizontal plane. The upper surface of the first overlapping portion 21 is the portion that abuts against the lower surface 50 (see FIG. 3) of the second overlapping portion 41 in the first overlapping portion 21. The upper surface 29 of the first overlapping portion 21 has a rectangular shape when viewed from the vertical direction. The lower surface 30 of the first overlapping portion 21 is the portion that abuts against the upper surface of the cap 4 in the first overlapping portion 21.

[0023] In the first overlapping portion 21, a relief groove 31 for avoiding a bolt 15 (see FIG. 4) for connecting a cap 4 to the upper part of the cylinder head 3 is formed. The relief groove 31 is recessed inside the first overlapping portion 21 at a position corresponding to one side of the upper surface 29 of the first overlapping portion 21. Note that the relief groove 31 may not be formed in the first overlapping portion 21. For example, the formation mode of the relief groove 31 can be changed according to the required specifications.

[0024] In the first overlapping portion 21, a through hole 32 that opens vertically so that the bolt 13 can be inserted is formed. Two through holes 32 are opened on the upper surface of the first overlapping portion 21. The first overlapping portion 21 has a first fitting portion 33 into which a ring 14 (see FIG. 4) that opens so that the bolt 13 can be inserted is fitted.

[0025] The first fitting portion 33 is provided in one of the two through holes 32 (the through hole on the side of the first shaft body 20). The first fitting portion 33 is a recess that depresses downward from the upper surface 29 in the first overlapping portion 21. When viewed in the vertical direction, the opening of the first fitting portion 33 is circular and larger than one of the through holes 32. The ring 14 is press-fitted and fixed to the first fitting portion 33.

[0026] <The second rocker shaft> As shown in FIG. 1, the second rocker shaft 12 is provided at the rear portion of the engine 1. The second rocker shaft 12 includes a second shaft body 40 that extends parallel to the axis C and in which a second oil passage 42 is formed, and a second overlapping portion 41 that overlaps the first overlapping portion 21 when viewed in a direction intersecting the axis C. For example, the total axial length L12 of the second rocker shaft 12 (the axial length including the second shaft body 40 and the second overlapping portion 41) is set to a length of 510 mm or more and 570 mm or less. For example, the total axial length L12 of the second rocker shaft 12 is the same as the total axial length L11 of the first rocker shaft 11 (L12 = L11).

[0027] As shown in FIG. 3, the second shaft body 40 is formed in a cylindrical shape that extends along the front-rear direction of the engine 1. For example, the axial length L40 of the second shaft body 40 is set to a length of 480 mm or more and 520 mm or less. For example, the axial length L40 of the second shaft body 40 is the same as the axial length L20 of the first shaft body 20 (L40 = L20, see FIG. 1). For example, the diameter D40 (maximum outer diameter) of the second shaft body 40 is set to a size of 30 mm or more and 50 mm or less. For example, the diameter D40 of the second shaft body 40 is the same as the diameter D20 of the first shaft body 20 (D40 = D20, see FIG. 1).

[0028] As shown in FIG. 1, the second oil passage 42 is formed to stop in front of the second overlapping portion 41. The second oil passage 42 has a second axial passage 43 extending along the axial direction of the second shaft body 40 and a second radial passage 44 (see FIG. 3) connected to the second axial passage 43 and extending along the radial direction of the second shaft body 40.

[0029] The length of the second axial passage 43 in the extending direction is shorter than the axial length L40 of the second shaft body 40. For example, the diameter D43 (opening diameter) of the second axial passage 43 is set to a size of 14 mm or more and 20 mm or less. For example, the diameter D43 of the second axial passage 43 is the same size as the diameter D23 of the first axial passage 23 (D43 = D23). As shown in FIG. 3, the second radial passage 44 opens to the outside in the radial direction of the second shaft body 40 at positions corresponding to the respective rocker arms 5, 6 (see FIG. 1).

[0030] As shown in FIG. 1, the second shaft body 40 is connected to the upper part of the cylinder head 3 by bolts 13 via a cap 4. As shown in FIG. 3, a through hole 45 is formed in the second shaft body 40 so as to open in the vertical direction through which the bolt 13 can be inserted. The second shaft body 40 has a plurality (for example, three in this embodiment) of upper seating surfaces 46 on which the heads of the bolts 13 are seated. The plurality of upper seating surfaces 46 are arranged at intervals in the axial direction of the second shaft body 40. The plurality of upper seating surfaces 46 are formed at the upper part of the second shaft body 40. The upper seating surface 46 has a rectangular shape having a length in the axial direction of the second shaft body 40 and being parallel to the horizontal plane. Two through holes 45 are opened in one upper seating surface 46.

[0031] The second shaft body 40 has a plurality (for example, three in this embodiment) of lower seating surfaces 47 that abut against the cap 4 (see FIG. 1). The lower seating surfaces 47 are formed at the lower part of the second shaft body 40. The lower seating surfaces 47 are arranged at positions overlapping the upper seating surfaces 46 when viewed from the vertical direction. The lower seating surface 47 has a rectangular shape having a length in the axial direction of the second shaft body 40 and being parallel to the horizontal plane.

[0032] On the second shaft body 40, a relief groove 48 for avoiding a bolt 15 (see FIG. 4) for connecting the cap 4 to the upper part of the cylinder head 3 is formed. The relief groove 48 is recessed radially inward of the second shaft body 40 at a position corresponding to one side of each seating surface 46, 47. Note that the relief groove 48 may not be formed in the second shaft body 40. For example, the formation mode of the relief groove 48 can be changed according to the required specifications.

[0033] As shown in FIG. 3, the second overlapping portion 41 is integrally connected to the upper front end of the second shaft body 40. The second overlapping portion 41 protrudes from the upper part of the front surface of the second shaft body 40 toward the front side of the engine 1. For example, the length L41 in the protruding direction of the second overlapping portion 41 is set to a length of 30 mm or more and 50 mm or less. For example, the length L41 in the protruding direction of the second overlapping portion 41 is the same as the length L21 in the protruding direction of the first overlapping portion 21 (L41 = L21, see FIG. 1).

[0034] The lower surface 50 (flat surface) of the second overlapping portion 41 is formed parallel to the horizontal plane. The lower surface 50 of the second overlapping portion 41 is the portion where the lower surface 50 of the second overlapping portion 41 abuts against the upper surface 29 (see FIG. 2) of the first overlapping portion 21. The lower surface 50 of the second overlapping portion 41 has a rectangular shape when viewed from the vertical direction. The upper surface 49 of the second overlapping portion 41 is the portion where the head of the bolt 13 seats on the second overlapping portion 41.

[0035] On the second overlapping portion 41, a relief groove 51 for avoiding a bolt 15 (see FIG. 4) for connecting the cap 4 to the upper part of the cylinder head 3 is formed. The relief groove 51 is recessed inside the second overlapping portion 41 at a position corresponding to one side of the upper surface 49 of the second overlapping portion 41. As shown in FIG. 5, the relief groove 51 of the second overlapping portion 41 is arranged at a position overlapping the relief groove 31 of the first overlapping portion 21 when viewed from the vertical direction. Note that the relief groove 51 may not be formed in the second overlapping portion 41. For example, the formation mode of the relief groove 51 can be changed according to the required specifications.

[0036] The second overlapping portion 41 is formed with a through hole 52 that opens vertically so that the bolt 13 can be inserted therethrough. Two through holes 52 are open on the upper surface 49 of the second overlapping portion 41. The second overlapping portion 41 has a second fitting portion 53 into which a ring 14 (see FIG. 4) that opens so that the bolt 13 can be inserted is fitted.

[0037] The second fitting portion 53 is provided in one of the two through holes 52 (the through hole on the side of the first shaft body 20). The second fitting portion 53 is a recess that depresses upward from the lower surface 50 in the second overlapping portion 41. When viewed in the vertical direction, the opening of the second fitting portion 53 is circular and larger than one of the through holes 52. The ring 14 is detachable with respect to the second fitting portion 53.

[0038] <Connection Structure at the Front of the First Rocker Shaft> As shown in FIG. 1, the front portion of the first rocker shaft 11 is connected to the upper portion of the cylinder head 3 via a cap 4 by a plurality (for example, two in this embodiment) of bolts 13 on the front end side of the engine 1. For example, the size (thickness) of the bolt 13 is M8 (nominal diameter). The two bolts 13 are arranged at intervals in the front-rear direction of the engine 1. As shown in FIG. 6, two female screw portions 60 that open upward so that the bolt 13 can be screwed are formed on the upper portion of the cylinder head 3.

[0039] The cap 4 is formed with two through holes 61 that open vertically so that the bolt 13 can be inserted therethrough. The cap 4 has a front lower fitting portion 62 into which a ring 14 that opens so that the bolt 13 can be inserted is fitted. The front lower fitting portion 62 is provided in one of the two through holes 61 (the through hole on the front side of the engine 1). The front lower fitting portion 62 is a recess that depresses downward from the upper surface in the cap 4. When viewed in the vertical direction, the opening of the front lower fitting portion 62 is circular and larger than one of the through holes 61. The ring 14 is press-fitted and fixed to the front lower fitting portion 62.

[0040] At the front portion of the first rocker shaft 11, two through holes 25 are formed which open vertically so that bolts 13 can be inserted. The front portion of the first rocker shaft 11 has a front upper fitting portion 34 into which a ring 14 that opens so that bolts 13 can be inserted is fitted. The front upper fitting portion 34 is provided in one of the two through holes 25 (the through hole on the front side of the engine 1). The front upper fitting portion 34 is a recess that is recessed upward from the lower seating surface 27 at the front portion of the first rocker shaft 11. When viewed in the vertical direction, the opening of the front upper fitting portion 34 is circular and larger than one of the through holes 25. The ring 14 is detachable with respect to the front upper fitting portion 34. Note that reference numeral 63 in the figure indicates an oil hole formed in the front portion of the first rocker shaft 11 and the cap 4.

[0041] For example, first, the cap 4 is placed on the upper surface of the cylinder head 3. Next, the front portion of the first rocker shaft 11 is placed on the upper surface of the cap 4. For example, the ring 14 protruding from the front lower fitting portion 62 of the cap 4 is fitted into the front upper fitting portion 34 of the first rocker shaft 11, and the lower seating surface 27 of the front portion of the first rocker shaft 11 is brought into contact with the upper surface of the cap 4. Next, the bolts 13 are inserted through the respective through holes 25 of the first rocker shaft 11 and the respective through holes 61 of the cap 4, and are screwed into the respective female screw portions 60 at the upper portion of the cylinder head 3. Thereby, the front portion of the first rocker shaft 11 can be connected to the upper portion of the cylinder head 3 via the cap 4.

[0042] <Connection Structure of Rear Portion of Second Rocker Shaft> As shown in FIG. 1, the rear portion of the second rocker shaft 12 is connected to the upper portion of the cylinder head 3 via the cap 4 by a plurality of (for example, two in the present embodiment) bolts 13 at the rear end side of the engine 1. For example, the size (thickness) of the bolts 13 is M8 (nominal diameter). The two bolts 13 are arranged at intervals in the front-rear direction of the engine 1. As shown in FIG. 7, two female screw portions 60 are formed in the upper portion of the cylinder head 3 which open upward so that bolts 13 can be screwed.

[0043] The cap 4 is formed with two through holes 61 that open vertically to allow the bolts 13 to pass through. The cap 4 has a rear lower fitting portion 64 into which a ring 14 that opens to allow the bolts 13 to pass through is fitted. The rear lower fitting portion 64 is provided in one of the two through holes 61 (the through hole on the front side of the engine 1). The rear lower fitting portion 64 is a recess that is recessed downward from the upper surface in the cap 4. When viewed in the vertical direction, the opening of the rear lower fitting portion 64 is circular and larger than one of the through holes 61. The ring 14 is press-fitted and fixed to the rear lower fitting portion 64.

[0044] At the rear part of the second rocker shaft 12, two through holes 45 are formed that open vertically to allow the bolts 13 to pass through. The rear part of the second rocker shaft 12 has a rear upper fitting portion 54 into which a ring 14 that opens to allow the bolts 13 to pass through is fitted. The rear upper fitting portion 54 is provided in one of the two through holes 45 (the through hole on the front side of the engine 1). The rear upper fitting portion 54 is a recess that is recessed upward from the lower seating surface 47 at the rear part of the second rocker shaft 12. When viewed in the vertical direction, the opening of the rear upper fitting portion 54 is circular and larger than one of the through holes 45. The ring 14 is detachable from the rear upper fitting portion 54. Note that reference numeral 65 in the figure indicates an oil hole formed in the rear part of the second rocker shaft 12 and the cap 4.

[0045] For example, first, place the cap 4 on the upper surface of the cylinder head 3. Next, place the rear part of the second rocker shaft 12 on the upper surface of the cap 4. For example, fit the ring 14 protruding from the rear lower fitting portion 64 of the cap 4 into the rear upper fitting portion 54 of the second rocker shaft 12, and bring the lower seating surface 47 of the rear part of the second rocker shaft 12 into contact with the upper surface of the cap 4. Next, insert the bolts 13 through the respective through holes 13 of the second rocker shaft 12 and the respective through holes 61 of the cap 4, and thread them into the respective female screw portions 60 at the upper part of the cylinder head 3. Thereby, the rear part of the second rocker shaft 12 can be connected to the upper part of the cylinder head 3 via the cap 4.

[0046] <Connection Structure of the First Overlapping Portion and the Second Overlapping Portion> As shown in FIG. 1, the first overlapping portion 21 and the second overlapping portion 41 are connected to the upper part of the cylinder head 3 via the cap 4 by a plurality of (for example, two in this embodiment) bolts 13 at the center in the front-rear direction of the engine 1. For example, the size (thickness) of the bolt 13 is M8 (nominal diameter). The two bolts 13 are arranged at intervals in the front-rear direction of the engine 1. The first overlapping portion 21 and the second overlapping portion 41 are arranged at positions overlapping each other when viewed from the vertical direction. As shown in FIG. 8, two female screw portions 60 that open upward so that the bolt 13 can be screwed are formed in the upper part of the cylinder head 3.

[0047] Two through holes 61 that open in the vertical direction so that the bolt 13 can be inserted are formed in the cap 4. The cap 4 has a central lower fitting portion 66 into which a ring 14 that opens so that the bolt 13 can be inserted is fitted. The central lower fitting portion 66 is provided in one of the two through holes 61 (the through hole on the front side of the engine 1). The central lower fitting portion 66 is a recess that is recessed downward from the upper surface in the cap 4. When viewed from the vertical direction, the opening of the central lower fitting portion 66 is a circular shape larger than that of one through hole 61. The ring 14 is press-fitted and fixed to the central lower fitting portion 66.

[0048] Two through holes 32 that open in the vertical direction so that the bolt 13 can be inserted are formed in the first overlapping portion 21. The first overlapping portion 21 has a central upper fitting portion 35 into which a ring 14 that opens so that the bolt 13 can be inserted is fitted. The central upper fitting portion 35 is provided in one of the two through holes 32 (the through hole on the front side of the engine 1). The central upper fitting portion 35 is a recess that is recessed upward from the lower surface 30 in the first overlapping portion 21. When viewed from the vertical direction, the opening of the central upper fitting portion 35 is a circular shape larger than that of one through hole 32. The ring 14 is detachable from the central upper fitting portion 35.

[0049] For example, first, place the cap 4 on the upper surface of the cylinder head 3. Next, place the first overlapping portion 21 on the upper surface of the cap 4. For example, fit the ring 14 protruding from the central lower fitting portion 66 of the cap 4 into the central upper fitting portion 35 of the first overlapping portion 21, and bring the lower surface 30 of the first overlapping portion 21 into contact with the upper surface of the cap 4.

[0050] Next, place the second overlapping portion 41 on the upper surface 29 of the first overlapping portion 21. For example, fit the ring 14 protruding from the first fitting portion 33 of the first overlapping portion 21 into the second fitting portion 53 of the second overlapping portion 41, and bring the lower surface 50 of the second overlapping portion 41 into contact with the upper surface 29 of the first overlapping portion 21. As a result, the first overlapping portion 21 and the second overlapping portion 41 are in a state of being in contact with each other in a plane. Also, the rear surface of the first overlapping portion 21 is in contact with the front surface of the second shaft body 40, and the front surface of the second overlapping portion 41 is in contact with the rear surface of the first shaft body 20.

[0051] Next, insert each bolt 13 through each through-hole 52 of the second overlapping portion 41, each through-hole 32 of the first overlapping portion 21, and each through-hole 61 of the cap 4, and thread them into each female screw portion 60 at the upper part of the cylinder head 3. Thereby, the first overlapping portion 21 and the second overlapping portion 41 can be connected to the upper part of the cylinder head 3 via the cap 4. The first rocker shaft 11 and the second rocker shaft 12 are joined by being clamped together by two bolts 13 at the first overlapping portion 21 and the second overlapping portion 41.

[0052] <Arrangement of each overlapping portion with respect to the exhaust-side rocker arm> As shown in FIG. 8, the second overlapping portion 41 is arranged closer to the exhaust-side rocker arm 6 than the first overlapping portion 21. The exhaust-side rocker arm 6 is supported via a bearing 7 at a portion (the front-end side portion of the second shaft body 40) adjacent to the second overlapping portion 41 in the second shaft body 40.

[0053] Note that the second radial passage 44 opens downward in the vertical direction (radially outside the second shaft body 40) from the second axial passage 43 at a position corresponding to the exhaust-side rocker arm 6, and communicates with the bearing 7.

[0054] <An example of the oil flow> For example, the oil pumped from the oil pan by an oil pump (not shown) passes through a filter and then through the internal passage of the cylinder block 2 shown in FIG. 1, and flows toward the upper end side of the cylinder head 3 through the oil passage formed at the outer end side in the front-rear direction of the engine 1 (see arrows W1 and W2 in FIG. 1). Thereafter, the oil enters the oil passages 22 and 42 of the rocker shafts 11 and 12 and flows inward in the front-rear direction of the engine 1 along the axial passages 23 and 43 (see arrows W3 and W4 in FIG. 1). Thereafter, the oil flows toward the bearings 7 of the rocker arms 5 and 6 through the radial passages 24 and 44 (see FIG. 8). Thereby, the bearing 7 can be lubricated.

[0055] <Function and effect> As described above, the rocker shaft connection structure 10 of the present embodiment includes a first rocker shaft 11 and a second rocker shaft 12 provided on the axis C of the first rocker shaft 11. The first rocker shaft 11 has a first overlapping portion 21 that overlaps the second rocker shaft 12 when viewed in a direction intersecting the axis C. The second rocker shaft 12 has a second overlapping portion 41 that overlaps the first overlapping portion 21 when viewed in a direction intersecting the axis C. The first overlapping portion 21 and the second overlapping portion 41 are connected to each other by bolts 13. According to this configuration, when viewed from a direction intersecting the axis C, the first overlapping portion 21 and the second overlapping portion 41 overlap each other, so that the circumferential position accuracy of the rocker shafts 11 and 12 can be improved as compared with the case where the ends of the pair of divided rocker shafts face each other in the axial direction. In addition, since the first overlapping portion 21 and the second overlapping portion 41 are connected to each other by the bolt 13, the bolt 13 can suppress the rocker shafts 11 and 12 from shifting in the axial direction. Therefore, the circumferential position accuracy of the rocker shafts 11 and 12 can be improved, and the rocker shafts 11 and 12 can be suppressed from shifting in the axial direction.

[0056] In the present embodiment, the first overlapping portion 21 and the second overlapping portion 41 are connected to each other by two bolts 13. According to this configuration, the support rigidity and the connection strength of the overlapping portions 21 and 41 can be increased as compared with the case where the first overlapping portion 21 and the second overlapping portion 41 are connected to each other by a single bolt 13. In addition, it is suitable for preventing the bolt 13 from breaking.

[0057] In the present embodiment, the first overlapping portion 21 and the second overlapping portion 41 are in contact with each other on the planes 29 and 50. According to this configuration, the circumferential position accuracy of the rocker shafts 11 and 12 can be improved as compared with the case where the first overlapping portion 21 and the second overlapping portion 41 are in contact with each other on a curved surface.

[0058] In the present embodiment, the second overlapping portion 41 is disposed closer to the exhaust-side rocker arm 6 than the first overlapping portion 21 and is disposed above the first overlapping portion 21 in the vertical direction. According to this configuration, the stress applied to the second overlapping portion 41 can be relaxed as compared with the case where the second overlapping portion 41 is disposed closer to the exhaust-side rocker arm 6 than the first overlapping portion 21 and is disposed below the first overlapping portion 21 in the vertical direction. Generally, the load by the exhaust-side rocker arm 6 is larger than the load by the intake-side rocker arm 5. For example, if the second overlapping portion 41 is arranged closer to the exhaust-side rocker arm 6 than the first overlapping portion 21 and is arranged below the first overlapping portion 21 in the vertical direction, when the second overlapping portion 41 receives a load that lifts upward in the vertical direction from the exhaust-side rocker arm 6, tensile stress acts on the second overlapping portion 41. As a result, stress concentration of tensile stress acts on the corner portion of the second overlapping portion 41, and there is a high possibility that the corner portion is damaged. On the other hand, according to this configuration, the second overlapping portion 41 is arranged closer to the exhaust-side rocker arm 6 than the first overlapping portion 21 and is arranged above the first overlapping portion 21 in the vertical direction. Even when the second overlapping portion 41 receives a load that lifts upward in the vertical direction (for example, in the direction of arrow F in FIG. 8) from the exhaust-side rocker arm 6, compressive stress acts on the second overlapping portion 41. Thereby, it is possible to suppress the stress concentration of tensile stress from acting on the corner portion of the second overlapping portion 41 and reduce the possibility that the corner portion is damaged.

[0059] In this embodiment, the first rocker shaft 11 has a first shaft body 20 that extends parallel to the axis C and in which a first oil passage 22 is formed. The second rocker shaft 12 has a second shaft body 40 that extends parallel to the axis C and in which a second oil passage is formed. The first oil passage 22 is formed so as to stop before the first overlapping portion 21. The second oil passage 42 is formed so as to stop before the second overlapping portion 41. According to this configuration, since no oil passage is formed in the first overlapping portion 21 and the second overlapping portion 41, the rigidity of the first overlapping portion 21 and the second overlapping portion 41 can be ensured.

[0060] In this embodiment, the first overlapping portion 21 has a first fitting portion 33 into which a ring 14 that opens so as to allow the bolt 13 to pass through is fitted. The second overlapping portion 41 has a second fitting portion 53 into which the ring 14 is fitted. According to this configuration, by fitting the ring 14 into the first fitting portion 33 and the second fitting portion 53, the positioning of the first overlapping portion 21 and the second overlapping portion 41 can be performed.

[0061] In this embodiment, the second overlapping portion 41 is disposed vertically above the first overlapping portion 21. The ring 14 is fixed to the first fitting portion 33 and is detachable from the second fitting portion 53. According to this configuration, when the second overlapping portion 41 is placed on the first overlapping portion 21 from above in the vertical direction, the ring 14 fixed to the first fitting portion 33 can be visually recognized, so that the assemblability is excellent.

[0062] In this embodiment, the total axial length L10 of the first rocker shaft 11 and the second rocker shaft 12 is 1 m or more. According to this configuration, the practical benefit of dividing the first rocker shaft 11 and the second rocker shaft 12 is greater compared to the case where the total axial length L10 of the first rocker shaft 11 and the second rocker shaft 12 is less than 1 m. By the way, there are the following problems with a rocker shaft having an overall length of 1 m or more. (1) A long hole for oil supply, a notch for a bolt, partial induction hardening, a predetermined surface accuracy (for example, 1.6S surface roughness), etc. are required. (2) It is very difficult to satisfy straightness, resulting in high costs. (3) Since the rocker arm rotates, a large number of people are required for assembly. On the other hand, according to this configuration, when the total axial length L10 of the first rocker shaft 11 and the second rocker shaft 12 is 1 m or more, by dividing the first rocker shaft 11 and the second rocker shaft 12 and shortening the shaft itself, all of the above problems (1) to (3) can be improved.

[0063] <Other Embodiments> In the above-described embodiment, an example in which the first overlapping portion and the second overlapping portion are connected to each other by two bolts has been described, but the present invention is not limited to this. For example, the first overlapping portion and the second overlapping portion may be connected to each other by a single bolt. For example, the first overlapping portion and the second overlapping portion may be connected to each other by three or more bolts. For example, the number of bolts installed can be changed according to the required specifications.

[0064] In the above-described embodiments, an example has been described in which the first overlapping portion and the second overlapping portion are in planar contact with each other, but the present invention is not limited to this. For example, the first overlapping portion and the second overlapping portion may be in curved surface contact with each other. For example, the contact mode of the first overlapping portion and the second overlapping portion can be changed according to the requirements specification.

[0065] In the above-described embodiments, an example has been described in which the second overlapping portion is disposed closer to the exhaust-side rocker arm than the first overlapping portion and is disposed above the first overlapping portion in the vertical direction, but the present invention is not limited to this. For example, the second overlapping portion may be disposed closer to the exhaust-side rocker arm than the first overlapping portion and may be disposed below the first overlapping portion in the vertical direction. For example, the arrangement mode of each overlapping portion with respect to the exhaust-side rocker arm and the arrangement mode of each overlapping portion in the vertical direction can be changed according to the requirements specification.

[0066] In the above-described embodiments, an example has been described in which the first oil passage is formed so as to stop in front of the first overlapping portion, and the second oil passage is formed so as to stop in front of the second overlapping portion, but the present invention is not limited to this. For example, the first oil passage may be formed to extend to the first overlapping portion, and the second oil passage may be formed to extend to the second overlapping portion. For example, oil passages may be formed in the first overlapping portion and the second overlapping portion. For example, the formation mode of the oil passage can be changed according to the requirements specification.

[0067] In the above-described embodiments, an example has been described in which the first overlapping portion has a first fitting portion into which a ring that can insert a bolt is fitted, and the second overlapping portion has a second fitting portion into which the ring is fitted, but the present invention is not limited to this. For example, each overlapping portion may not have a fitting portion into which the ring is fitted. For example, the installation mode of the fitting portion can be changed according to the requirements specification.

[0068] In the above-described embodiment, an example has been described in which the second overlapping portion is disposed vertically above the first overlapping portion, and the ring is fixed to the first fitting portion and detachable from the second fitting portion. However, the present invention is not limited to this. For example, the second overlapping portion may be disposed vertically below the first overlapping portion. For example, the ring may be detachable from the first fitting portion and fixed to the second fitting portion. For example, the arrangement mode of each overlapping portion in the vertical direction and the fitting mode of the ring with respect to each fitting portion can be changed according to the required specifications.

[0069] In the above-described embodiment, an example has been described in which the total axial lengths of the first rocker shaft and the second rocker shaft are 1 m or more. However, the present invention is not limited to this. For example, the total axial lengths of the first rocker shaft and the second rocker shaft may be less than 1 m. For example, the total axial lengths of the first rocker shaft and the second rocker shaft can be changed according to the required specifications.

[0070] In the above-described embodiment, an example has been described in which the first overlapping portion and the second overlapping portion are disposed at positions overlapping each other when viewed from the vertical direction. However, the present invention is not limited to this. For example, the first overlapping portion and the second overlapping portion may be disposed at positions overlapping each other when viewed from the horizontal direction. For example, the first overlapping portion and the second overlapping portion may be disposed at positions overlapping each other when viewed from a direction intersecting the vertical direction. For example, the first overlapping portion and the second overlapping portion may be disposed at positions overlapping each other when viewed from a direction intersecting the axis. For example, the overlapping mode of the first overlapping portion and the second overlapping portion can be changed according to the required specifications.

[0071] In the above-described embodiment, the rocker shaft connection structure provided in the diesel engine has been described as an example. However, the present invention is not limited to this. For example, the rocker shaft connection structure may be provided in a gasoline engine. For example, the mode of the engine in which the rocker shaft connection structure is provided can be changed according to the required specifications.

[0072] Although the embodiments of the present invention have been described above, the present invention is not limited thereto, and additions, omissions, substitutions, and other modifications of the configuration are possible without departing from the spirit of the present invention, and it is also possible to appropriately combine the above-described embodiments.

Explanation of Reference Numerals

[0073] 6... Exhaust-side rocker arm, 10... Rocker shaft connection structure, 11... First rocker shaft, 12... Second rocker shaft, 13... Bolt, 14... Ring, 20... First shaft body, 21... First overlapping portion, 22... First oil passage, 29... Upper surface (plane) of the first overlapping portion, 33... First fitting portion, 40... Second shaft body, 41... Second overlapping portion, 42... Second oil passage, 50... Lower surface (plane) of the second overlapping portion, 53... Second fitting portion, C... Axis, L10... Total axial length of the first rocker shaft and the second rocker shaft

Claims

1. A first rocker shaft and, a second rocker shaft provided on the axis of the first rocker shaft, comprising: The first rocker shaft has a first overlapping portion that overlaps the second rocker shaft when viewed from a direction intersecting the axis, The second rocker shaft has a second overlapping portion that overlaps the first overlapping portion when viewed from a direction intersecting the axis, The first overlapping portion and the second overlapping portion are connected to each other by bolts, The first rocker shaft has a first shaft body that extends parallel to the axis and in which a first oil passage is formed, The second rocker shaft has a second shaft body that extends parallel to the axis and in which a second oil passage is formed, The first oil passage is formed so as to stop in front of the first overlapping portion, The second oil passage is formed so as to stop in front of the second overlapping portion A rocker shaft connection structure.

2. The first overlapping portion and the second overlapping portion are connected to each other by a plurality of the bolts The rocker shaft connection structure according to Claim 1.

3. The first overlapping portion and the second overlapping portion are in contact with each other in a plane The rocker shaft connection structure according to Claim 1 or 2.

4. The second overlapping portion is disposed above the first overlapping portion in the vertical direction The rocker shaft connection structure according to any one of Claims 1 to 3.

5. The first overlapping portion has a first fitting portion into which a ring that opens to allow the bolt to pass through is fitted, The second overlapping portion has a second fitting portion into which the ring is fitted The rocker shaft connection structure according to any one of Claims 1 to 4.

6. The second overlapping portion is disposed above the first overlapping portion in the vertical direction, The ring is fixed to the first fitting portion and is detachable from the second fitting portion The rocker shaft connection structure according to Claim 5.

7. The total axial length of the first rocker shaft and the second rocker shaft is 1 m or more The rocker shaft connection structure according to any one of Claims 1 to 6.

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