JP7310122B2 - Rocker shaft support structure - Google Patents

Description

The present invention relates to a support structure for a rocker shaft mounted on an internal combustion engine.

Some overhead cam internal combustion engines transmit the action of a rotating cam to an oscillating rocker arm to open and close valves via the rocker arm. For example, a camshaft and a rocker shaft are arranged parallel to each other above the cylinder head, and a rocker arm supported on the rocker shaft contacts the cam supported on the camshaft. When the cam rotates along with the camshaft, the rocker arm swings around the rocker shaft to reciprocate the intake and exhaust valves.

As a support structure for a rocker shaft, a semi-cylindrical recessed bearing is provided in a camshaft holder provided in the upper part of the cylinder head, and a bolt or the like is passed through the rocker shaft supported by the bearing to fix it. (Patent Document 1).

Japanese Patent Publication No. 62-15732

In the support structure of the rocker shaft in Patent Literature 1, it is difficult to accurately determine the position and shape of the semi-cylindrical concave bearing portion. In addition, the semi-cylindrical concave bearing portion may be difficult to obtain strong holding strength against a load in a specific direction. For example, the concave inner surface of the bearing cannot receive the load that pulls up (disengages) the rocker shaft in the direction in which the concave bearing is open. In addition, the bearing may be deformed by a strong load to change the diameter of the opening, which may degrade the accuracy of supporting the rocker shaft.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a rocker shaft support structure that is simple in structure and excellent in holding the rocker shaft.

The present invention is an internal combustion engine that includes a rocker arm that swings to operate a valve by rotation of a cam that is supported by a camshaft, and a rocker shaft that swingably supports the rocker arm, and supports the rocker shaft. In the rocker shaft support structure, a through hole is formed in the rocker shaft and penetrates in a direction intersecting the axial direction at a position different from the support location of the rocker arm in the axial direction in which the rocker shaft extends, and the support member is formed with the through hole. a shaft support hole that penetrates in the axial direction and surrounds and supports a partial region of the rocker shaft in the axial direction including the portion where the through hole is formed; Extending in an intersecting direction and communicating with the shaft support hole, the rocker shaft is inserted and supported in the shaft support hole. A fastening hole extending in a direction intersecting the axial direction and having a threaded portion formed on the inner surface thereof, a shaft fixing hole and a through hole, and screwed to the threaded portion of the fastening hole to form a rocker shaft. a bolt for fixing the support members together to the cylinder head, the bolt having a shaft portion that can be inserted into the shaft fixing hole and the through hole, and a head portion having a larger diameter than the shaft portion; has a flat portion on its outer surface against which the head of the bolt abuts when fixed by a bolt, and the shaft fixing hole has a large-diameter opening that accommodates the head of the bolt inside when the head of the bolt abuts on the flat portion. and the upper surface of the head accommodated in the large-diameter opening is positioned below the upper surface of the support member .

According to the present invention, it is possible to obtain a rocker shaft support structure that has a simple configuration and is excellent in holding the rocker shaft.

FIG. 2 is a perspective view showing the rocker shaft support structure of the embodiment; FIG. 2 is a perspective view of the rocker shaft support structure viewed from a direction different from that of FIG. 1; FIG. 4 is a top view of the rocker shaft support structure; FIG. 4 is a cross-sectional view of the rocker shaft support structure taken along line AA of FIG. 3; FIG. 4 is a cross-sectional view of the rocker shaft support structure before fastening bolts are attached;

Hereinafter, this embodiment will be described in detail with reference to the accompanying drawings. In addition, the present invention is not limited to the configuration shown below, and can be modified as appropriate. Also, in the following description, a configuration in which the technology of the present disclosure is applied to a vehicle will be described, but it can be applied to other vehicles in which an internal combustion engine is installed, and internal combustion engines mounted on other than vehicles. Moreover, even if not explicitly shown in each drawing, it is assumed that a vehicle normally has a configuration.

A cylinder head 10 shown in FIGS. 1 to 5 constitutes an engine for a motorcycle. Although illustration of the entire engine is omitted, a cylinder head 10 is provided on top of a cylinder (not shown) in which a piston (not shown) is reciprocatably accommodated. A housing space 11 is formed in the upper portion of the cylinder head 10, and a cylinder head cover (not shown) covering the housing space 11 is attached. The upper edge of the cylinder head 10 is formed with a mating surface 12 to be mated with the cylinder head cover.

A shaft housing 20 is supported on a support block 13 formed within a housing space 11 of the cylinder head 10 . As shown in FIGS. 4 and 5 , the upper surface of the support block 13 is a planar mounting surface 14 , and the lower surface 21 of the shaft housing 20 is in contact with and supported by the mounting surface 14 . The lower surface 21 is also planar.

The shaft housing 20 is a support member that supports a later-described camshaft 30 and a pair of rocker shafts 32 and 33 . The camshaft 30 and the pair of rocker shafts 32, 33 are supported in parallel. In the following description, the direction along the central axis of the camshaft 30 and the pair of rocker shafts 32 and 33 (the direction parallel to the central axis) is called the axial direction. A direction perpendicular to the axial direction when the cylinder head 10 is viewed from above as shown in FIG. 3 is called a width direction. In each drawing, the arrow X indicates the axial direction, and the arrow Y indicates the width direction.

A camshaft 30 is supported within a shaft hole (not shown) formed by the support block 13 and the shaft housing 20 . The camshaft 30 is rotatably supported around its own central axis. The camshaft 30 supports an intake valve cam (not shown) and an exhaust valve cam (not shown) at different axial positions. As shown in FIGS. 1 and 3 , one axial end of the camshaft 30 protrudes from the support block 13 and the shaft housing 20 . A timing pulley 31 (FIG. 3) is provided at the projecting end of the camshaft 30 . A timing belt (not shown) is attached to the timing pulley 31 , and the rotational force of a crankshaft (not shown) of the engine is transmitted to the timing pulley 31 via the timing belt to rotate the camshaft 30 . A timing sprocket and a timing chain may be used to transmit the driving force instead of the timing pulley 31 and the timing belt.

A rocker shaft 32 and a rocker shaft 33 are arranged on both widthwise sides of the camshaft 30 . Each of the rocker shaft 32 and the rocker shaft 33 is a shaft with a circular cross section and has a cylindrical outer peripheral surface. Each of the rocker shafts 32 and 33 is supported and fixed to the cylinder head 10 and the shaft housing 20 by a support structure, which will be described later, with their central axes directed parallel to the central axis of the camshaft 30 . A rocker arm 40 is rockably supported by the rocker shaft 32 , and a rocker arm 50 is rockably supported by the rocker shaft 33 .

The rocker arm 40 has a sleeve 41 with a cylindrical inner peripheral surface, and the rocker shaft 32 is inserted through the sleeve 41 . By bringing the inner peripheral surface of the sleeve 41 into sliding contact with the outer peripheral surface of the rocker shaft 32 , the rocker arm 40 swings around the rocker shaft 32 . A biasing spring 34 that is a compression coil spring is arranged outside the rocker shaft 32 . The rocker arm 40 is pressed by the biasing spring 34 and abuts against the shaft housing 20 to determine its axial position.

The rocker arm 40 has a first arm 42 and a second arm 43 that protrude laterally (in the width direction) from the sleeve 41 . The first arm 42 supports a roller 44 that is rotatable around an axis facing the axial direction, and the roller 44 contacts the intake valve cam. A pair of the second arms 43 are provided at different positions in the axial direction, and the tip of each of the second arms 43 abuts on a pressed portion 45 provided at the end of the intake valve. The intake valve receives a biasing force in a pushing-up direction from a valve spring 46 arranged between the pressed portion 45 and the inner surface of the accommodation space 11 . This urging force presses the roller 44 against the intake valve cam.

The rocker arm 50 has a sleeve 51 having a cylindrical inner peripheral surface, and the rocker shaft 33 is inserted through the sleeve 51 . By bringing the inner peripheral surface of the sleeve 51 into sliding contact with the outer peripheral surface of the rocker shaft 33 , the rocker arm 50 swings around the rocker shaft 33 . A biasing spring 35 that is a compression coil spring is arranged outside the rocker shaft 33 . The rocker arm 50 is pressed by the urging spring 35 to abut against the shaft housing 20 to determine its position in the axial direction.

The rocker arm 50 has a first arm 52 and a second arm 53 that protrude laterally (in the width direction) from the sleeve 51 . A roller 54 is supported by the first arm 52 and is rotatable around an axis facing the axial direction, and the roller 54 abuts on the exhaust valve cam. A pair of the second arms 53 are provided at different positions in the axial direction, and the tip of each of the second arms 53 abuts on a pressed portion 55 provided at the end of the exhaust valve. The exhaust valve receives an upward biasing force from a valve spring 56 arranged between the pressed portion 55 and the inner surface of the accommodation space 11 . This urging force presses the roller 54 against the exhaust valve cam.

The intake valve opens and closes between an intake port (not shown) formed in the cylinder head 10 and a combustion chamber (not shown). The exhaust valve opens and closes between an exhaust port (not shown) formed in the cylinder head 10 and a combustion chamber (not shown). When the camshaft 30 rotates, the intake valve cam and the exhaust valve cam press the rollers 44 and 54 upward at different timings. When the roller 44 is pushed, the second arm 43 of the rocker arm 40 pushes down the pushed portion 45 against the urging force of the valve spring 46 to open the intake valve. When the roller 54 is pushed, the second arm 53 of the rocker arm 50 pushes down the pushed portion 55 against the biasing force of the valve spring 56, thereby opening the exhaust valve. When the rocker arm 40 and the rocker arm 50 are released from the pressure exerted by the intake valve cam and the exhaust valve cam, the biasing forces of the valve springs 46 and 56 close the intake valve and the exhaust valve, respectively.

The sleeve 41 of the rocker arm 40 and the sleeve 51 of the rocker arm 50 are supported by axial intermediate portions of the rocker shafts 32 and 33 . The rocker shafts 32 and 33 are supported by the shaft housing 20 at locations axially different from the regions where the rocker arms 40 and 50 are supported. The support structure for the rocker shafts 32 and 33 will be described in detail below.

The shaft housing 20 has a support block 22 at one axial end and a support block 23 at the other axial end. The support block 22 and the support block 23 constitute a shaft support portion that supports the rocker shafts 32 and 33 . The support block 22 and the support block 23 are connected by a pair of connecting portions 24 extending in the axial direction. The pair of connection portions 24 are spaced apart in the width direction, and the camshaft 30 is positioned between the pair of connection portions 24 in the width direction. A support portion 25 for supporting the camshaft 30 is formed at the lower center in the width direction of the support block 22 (see FIG. 1). A support portion 26 for supporting the camshaft 30 is formed at the lower center in the width direction of the support block 23 (see FIG. 2).

The support block 22 is formed with a pair of shaft support holes 27 extending axially through the support block 22 at different positions in the width direction. The pair of shaft support holes 27 are positioned on both sides of the shaft support portion 25 in the width direction and positioned above the shaft support portion 25 . The support block 23 is formed with a pair of shaft support holes 28 extending axially through the support block 23 at different positions in the width direction. The pair of shaft support holes 28 are located on both sides of the shaft support portion 26 in the width direction and above the shaft support portion 26 . One shaft support hole 27 and one shaft support hole 28 are coaxially aligned in the axial direction, and the other shaft support hole 27 and the other shaft support hole 28 are coaxially aligned in the axial direction. Each shaft support hole 27 and each shaft support hole 28 are circular holes having a cylindrical inner peripheral surface and have the same inner diameter.

A rocker shaft 32 is inserted into one shaft support hole 27 and one shaft support hole 28 that are aligned in the axial direction, and the other shaft support hole 27 that is aligned in the axial direction and the other shaft support. A rocker shaft 33 is inserted into the hole 28 . That is, both the rocker shaft 32 and the rocker shaft 33 are supported by a double support structure by the support block 22 and the support block 23 spaced apart in the axial direction. The support structure for the rocker shaft 32 and the support structure for the rocker shaft 33 are similar, and the support structure for the rocker shaft 32 will be described below as a representative. The supporting structure of the rocker shaft 33 is denoted by the same reference numerals as those of the supporting structure of the rocker shaft 32 in each drawing, and redundant description is omitted.

As shown in FIGS. 4 and 5, the support blocks 22 and 23 have fixed shafts extending perpendicularly to the axial direction from the upper surface (top surface) to the lower surface 21 of each support block 22 and 23 . A hole 60 and a shaft fixing hole 61 are formed. The shaft fixing hole 60 intersects with the shaft supporting hole 27, and the shaft fixing hole 60 is vertically divided across the shaft supporting hole 27. - 特許庁A large-diameter opening 60 a that opens toward the upper surface side of the support block 22 is formed in a portion of the shaft fixing hole 60 above the shaft support hole 27 . The shaft fixing hole 60 is a circular hole having a cylindrical inner peripheral surface, and the large-diameter opening 60 a has a larger inner diameter than the portion of the shaft fixing hole 60 below the shaft support hole 27 . The shaft fixing hole 61 intersects with the shaft support hole 28, and the shaft fixing hole 61 is vertically divided across the shaft support hole 28. - 特許庁A large-diameter opening 61 a that opens toward the upper surface side of the support block 23 is formed in a portion of the shaft fixing hole 61 above the shaft support hole 28 . The shaft fixing hole 61 is a circular hole having a cylindrical inner peripheral surface, and the large diameter opening 61 a has a larger inner diameter than the portion of the shaft fixing hole 61 below the shaft support hole 28 .

As shown in FIGS. 4 and 5, the support block 13 of the cylinder head 10 has a fastening hole opening on the mounting surface 14 with an axial distance corresponding to the shaft fixing hole 60 and the shaft fixing hole 61 . 62 and a fastening hole 63 are formed. The fastening holes 62 and 63 are circular holes each having a cylindrical inner peripheral surface. 63a is formed.

As shown in FIGS. 4 and 5, the rocker shaft 32 has a through hole 64 extending therethrough in a direction perpendicular to the axial direction with an axial space corresponding to the shaft fixing hole 60 and the shaft fixing hole 61 . and a through hole 65 are formed. The through hole 64 and the through hole 65 are formed parallel to each other, and flat portions 64a and 65a forming part of the outer surface of the rocker shaft 32 are formed on the peripheral edge of one end of the through hole 64 and the through hole 65. is formed (see FIG. 5). The through hole 64 and the through hole 65 are circular holes each having a cylindrical inner peripheral surface, and the flat portion 64a and the flat portion 65a are annular flat surfaces having diameters larger than the inner diameters of the through holes 64 and 65, respectively. is.

4 and 5, the rocker shaft 32 is formed with an axial hole 66 extending in the axial direction. The axial hole 66 opens at one axial end of the rocker shaft 32 and the other end of the axial hole 66 is closed. The opening of the axial hole 66 on one end side in the axial direction is closed with a cap 67 . The axial hole 66 communicates with each of the through holes 64 and 65 . A plurality of oil supply holes 68 are formed radially penetrating from the axial hole 66 to the outer peripheral surface of the rocker shaft 32 .

A positioning hole 69 is further formed in the rocker shaft 32 at a position closer to the end than the through hole 64 . The positioning hole 69 extends parallel to the through holes 64 and 65 and radially penetrates the rocker shaft 32 . A positioning pin 70 is inserted into the positioning hole 69 . The positioning pin 70 protrudes from the outer peripheral surface of the rocker shaft 32 .

The rocker shaft 32 is axially inserted into the shaft support holes 27 and 28 . More specifically, it is inserted from the shaft support hole 27 of the support block 22 toward the shaft support hole 28 of the support block 23 with the end closed by the cap 67 leading. During this insertion, the bias spring 34 and the sleeve 41 of the rocker arm 40 are positioned between the support block 22 and the support block 23, and the rocker shaft 32 is also inserted into the bias spring 34 and the sleeve 41. (See Figure 5). When the positioning pin 70 reaches the position where it contacts the axial end face of the support block 22, further insertion of the rocker shaft 32 is restricted. In this state, the axial positions of the shaft fixing hole 60 and the through hole 64 are aligned, and the axial positions of the shaft fixing hole 61 and the through hole 65 are aligned.

As shown in FIG. 5, with the axial positions of the shaft fixing hole 60 and the fastening hole 62 aligned, and the axial positions of the shaft fixing hole 61 and the fastening hole 63 aligned, the mounting surface of the cylinder head 10 was formed. A lower surface 21 of shaft housing 20 is supported on 14 . Positioning means (not shown) is provided for positioning the shaft housing 20 with respect to the cylinder head 10 in a state in which the shaft fixing hole 60 communicates with the fastening hole 62 and the shaft fixing hole 61 communicates with the fastening hole 63 .

After the positioning of the shaft housing 20 with respect to the cylinder head 10 and the insertion of the rocker shaft 32 into the shaft housing 20 (the shaft support hole 27 and the shaft support hole 28) are performed as described above, the shaft fixing hole 60 is fastened. The axial positions of the hole 62 and the through hole 64 are aligned, and the axial positions of the shaft fixing hole 61, the fastening hole 63 and the through hole 65 are aligned. Further, by setting the position of the rocker shaft 32 around the axis, the through hole 64 is aligned coaxially with the shaft fixing hole 60 and the fastening hole 62, the flat portion 64a faces the large diameter opening 60a side, and the through hole 65 is aligned with the shaft. The fixing hole 61 and the fastening hole 63 are aligned coaxially, and the flat portion 65a faces the large-diameter opening 61a. Since the protruding direction of the positioning pin 70 and the orientation of the flat portion 64a and the flat portion 65a match, the position of the rocker shaft 32 around the axis can be adjusted by using the positioning pin 70 as an index so that it faces the upper surface side of the support block 22. can be performed easily and reliably. FIG. 5 shows a state in which the above setting is completed.

Then, the shaft housing 20 and the rocker shaft 32 are collectively fixed (fastened together) to the cylinder head 10 using the fastening bolts 71 and 72 which are fixing members. The fastening bolt 71 and the fastening bolt 72 respectively have a shaft portion 71a and a shaft portion 72a having male threads on the outer surface, and a head portion 71b and a head portion 72b located at the ends. The head portion 71b and the head portion 72b have a larger diameter than the shaft portion 71a and the shaft portion 72a. It is flat. A male screw is formed only in a partial area from the tip side of the shaft portion 71a and the shaft portion 72a, and a male screw is not formed in a region close to the head portion 71b and the head portion 72b. The shaft portion 71 a has a length that passes through the shaft fixing hole 60 and the through hole 64 and reaches the fastening hole 62 , and the shaft portion 72 a passes through the shaft fixing hole 61 and the through hole 65 to reach the fastening hole 63 . It has a length that reaches

The fastening bolt 71 is inserted into the shaft fixing hole 60, the through hole 64, and the fastening hole 62 downward from the side of the large diameter opening 60a with the end of the shaft portion 71a leading. When the fastening bolt 71 is inserted by a predetermined amount, the threaded portion of the shaft portion 71a reaches the female threaded portion 62a. When the fastening bolt 71 is rotated in the screwing direction in this state, the male thread is screwed into the female thread portion 62a. When the bottom surface of the head portion 71b comes into contact with the flat portion 64a, further insertion of the fastening bolt 71 is restricted, and tightening and fixing by the fastening bolt 71 is completed by applying a tightening axial force with a predetermined torque (see FIG. 4). state shown). In this state, the head 71b of the fastening bolt 71 is housed inside the large diameter opening 60a.

Similar to the fastening bolt 71, the fastening bolt 72 is inserted into the shaft fixing hole 61, the through hole 65, and the fastening hole 63 downward from the large diameter opening 61a with the end of the shaft portion 72a leading. When the fastening bolt 72 is inserted by a predetermined amount, the threaded portion of the shaft portion 72a reaches the female threaded portion 63a. When the fastening bolt 72 is rotated in the screwing direction in this state, the male thread is screwed into the female thread portion 63a. When the bottom surface of the head portion 72b comes into contact with the flat portion 65a, further insertion of the fastening bolt 72 is restricted, and tightening and fixing by the fastening bolt 72 is completed by applying a tightening axial force with a predetermined torque (see FIG. 4). state shown). In this state, the head 72b is accommodated inside the large diameter opening 61a.

When the shaft housing 20 and the rocker shaft 32 are fixed to the cylinder head 10 using the fastening bolts 71 and 72 through the above process, the rocker shaft 32 is supported as shown in FIGS. The rocker arm 40 is pushed toward the support block 23 by the biasing force of the biasing spring 34 inserted between the sleeve 41 and the support block 22 , thereby adjusting the axial position of the rocker arm 40 on the rocker shaft 32 . is determined.

Further, using the support structure of the rocker shaft 32, an oil passage is formed for supplying oil for lubricating the periphery of the rocker arm 40. As shown in FIG. An oil passage (not shown) communicating with the fastening hole 63 is formed inside the cylinder head 10 . The inner diameter of the fastening hole 63 is larger at the upper portion near the mounting surface 14 than at the inner diameter of the lower portion (back side) having the female screw portion 63a. There is a predetermined gap between it and the fastening hole 63 . There are also predetermined gaps between the shaft fixing hole 61 and the shaft portion 72a in the shaft housing 20 and between the through hole 65 and the shaft portion 72a in the rocker shaft 32, respectively. Therefore, the oil supplied into the fastening hole 63 at a predetermined pressure by an oil pump (not shown) flows from the fastening hole 63 through the gap with the shaft portion 72a and into the shaft fixing hole 61 and the through hole 65, whereupon the locker is driven. It flows into axial bore 66 of shaft 32 .

At the boundary between the fastening hole 63 and the shaft fixing hole 61 , the mounting surface 14 and the lower surface 21 are in close contact with each other due to the tightening axial force of the fastening bolt 71 and the fastening bolt 72 . No oil leakage to Also, at the boundary between the shaft fixing hole 61 and the through hole 65, the outer peripheral surface of the rocker shaft 32 is in close contact with the inner peripheral surface of the shaft support hole 28 due to the tightening axial force, so oil leakage to the outside does not occur. Furthermore, since the bottom surface of the head portion 72b of the fastening bolt 72 is in close contact with the flat portion 65a formed in the opening portion on the top side of the through hole 65 due to the tightening axial force, the head portion 72b functions as a sealing lid. As a result, oil leakage to the large-diameter opening 61a side is also prevented. Therefore, oil is supplied from the fastening hole 63 to the axial hole 66 without oil leakage to the outside. The oil that has entered the axial hole 66 is restricted from moving toward one end in the axial direction of the rocker shaft 32 by the cap 67 and flows toward the other end in the axial direction. Along the way, oil is supplied to the outer peripheral surface of the rocker shaft 32 through a plurality of oil supply holes 68 provided in the rocker shaft 32 to lubricate the space between the rocker shaft 32 and the sleeve 41 .

The support block 22 side, which is fastened by the fastening bolt 71, is structured to prevent oil from leaking to the outside, similarly to the support block 23 side, which is fastened by the fastening bolt 72. That is, the bottom surface of the head 71b of the fastening bolt 71 is in close contact with the flat portion 64a of the through hole 64 due to the tightening axial force, and the head 71b functions as a sealing lid to prevent oil leakage toward the large diameter opening 60a. prevent. Fastening bolts are provided between the rocker shaft 32 (through hole 64) and the support block 22 (shaft support hole 27) and between the support block 22 (shaft fixing hole 60) and the cylinder head 10 (fastening hole 62). The tightening axial force of 71 and 72 keeps them in close contact to prevent oil leakage to the outside.

Rocker shaft 33 is supported by a support structure similar to rocker shaft 32 described above. Specifically, the rocker shaft 32 , biasing spring 34 , and rocker arm 40 in the above description are read as the rocker shaft 33 , biasing spring 35 , and rocker arm 50 , respectively, to provide a support structure for the rocker shaft 33 .

In the support structure for the rocker shaft 32 (33) according to the present embodiment described above, the shaft support holes 27 and 28 penetrating in the axial direction are provided in the shaft housing 20, and the rocker shaft 32 (33) is inserted into the shaft support holes 27 and 28. Insert and support. The rocker shaft 32 (33) is formed with through holes 64 and 65 penetrating in a direction perpendicular to the axial direction at positions axially different from the supporting portion of the rocker arm 40 (50). The shaft support holes 27 and 28 surround and support a partial region of the rocker shaft 32 (33) in the axial direction including the locations where the through holes 64 and 65 are formed.

The shaft support holes 27 and 28 have inner peripheral surfaces along the entire circumference of the rocker shaft 32 (33) in the circumferential direction around the central axis of the rocker shaft 32 (33). is a hole. Therefore, compared to a structure in which a support surface exists only partially in the circumferential direction, the support area of the shaft housing 20 with respect to the rocker shaft 32 (33) is large, and high support accuracy and support strength can be obtained. Further, since the shaft support holes 27 and 28 are all-around holes, even if a load is applied in any direction orthogonal to the axial direction, there is always a support surface for the rocker shaft 32 (33) to absorb the load. Can receive. Furthermore, the rigidity of the shaft support holes 27 and 28, which are all-round holes, is ensured by the meat portions of the support blocks 22 and 23 that surround the periphery, so deformation due to loads in a specific direction is unlikely to occur, and the hole shape can be formed with high precision. can be kept in Therefore, by supporting the rocker shaft 32 (33) with the shaft support holes 27 and 28, it is possible to obtain a high level of support strength regardless of the load direction.

In addition, the radial position of the rocker shaft 32 (33) is determined with high precision by the aligning action of the cylindrical inner peripheral surfaces of the shaft support holes 27 and 28, eliminating the need to use separate positioning means. Further, the positioning of the rocker shaft 32 (33) in the axial direction and the circumferential direction can be easily performed using the positioning pin 70 .

The shaft support holes 27, 28 axially penetrating the support blocks 22, 23 can be formed by a simple drilling process for the shaft housing 20, enabling parts supply with high precision and high productivity. In particular, since the shaft support holes 27 and 28 are holes in which a circular (perfect circle) cross section with a constant inner diameter size continues in the axial direction, there is an advantage that it is easy to obtain a highly accurate inner surface shape at low cost.

Further, the through holes 64 and 65 provided in the rocker shaft 32 (33) and the shaft fixing holes 60 and 61 provided in the shaft housing 20 can also be formed by simple drilling, resulting in high precision and high productivity. Parts supply can be realized.

In this embodiment, the shaft housing 20 that has the shaft support holes 27 and 28 and directly supports the rocker shaft 32 (33) is formed separately from the cylinder head 10 . Then, using the fastening bolts 71 and 72, the rocker shaft 32 (33) and the shaft housing 20 are collectively fixed to the cylinder head 10. As shown in FIG. This fixed structure also has advantages.

First, by making the shaft housing 20 separate from the cylinder head 10, it is possible to improve workability when forming the shaft support holes 27, 28 and the shaft fixing holes 60, 61. FIG. Since the cylinder head 10 constitutes a combustion chamber, an intake port, an exhaust port, etc., it is required to have particularly high rigidity and heat resistance among the components of the engine, and the size of the part is also large. On the other hand, the shaft housing 20 is arranged at a distance from the combustion chamber to some extent, and only needs to be large enough to support the rocker shaft 32 (33) and the camshaft 30. Therefore, compared to the cylinder head 10, The requirements for strength, heat resistance, etc. are relaxed, and the size can be reduced. Therefore, forming the portions corresponding to the shaft support holes 27 and 28 and the shaft fixing holes 60 and 61 in the shaft housing 20 is superior in workability to forming in the cylinder head 10, and the accuracy of each hole is improved. is also easy to raise.

Further, by fixing the fastening bolts 71 and 72 to the cylinder head 10, the support strength is improved. As described above, since the cylinder head 10 has high rigidity, it is advantageous in terms of strength that the load acting on the rocker shaft 32 (33) and the shaft housing 20 is ultimately received by the cylinder head 10 .

For example, when a load that presses the rocker shaft 32 (33) downward is applied, the inner peripheral surfaces of the shaft support holes 27 and 28 are pressed, and the shaft housing 20 receives the downward load. This downward load is transmitted from the lower surface 21 of the shaft housing 20 to the mounting surface 14 of the support block 13 and received by the cylinder head 10 . Since the compressive load from the top to the bottom is sequentially transmitted from the shaft housing 20 to the cylinder head 10, the load can be reliably received by the cylinder head 10 having excellent rigidity.

Conversely, when a load acts to lift the rocker shaft 32 (33) upward, force is applied from the flat surfaces 64a and 65a to the heads 71b and 72b of the fastening bolts 71 and 72, causing the fastening bolts 71 and 72 to move upward. is pressed down. The fastening bolts 71 and 72 are not directly fixed to the shaft housing 20 (only the shaft portions 71a and 72a are inserted through the shaft fixing holes 60 and 61). Therefore, the upward load acting on the fastening bolts 71 and 72 acts on the threaded portions of the fastening holes 62 and 63 to the female thread portions 62a and 63a. That is, the load in the lifting direction is received by the highly rigid cylinder head 10 , and the load in the lifting direction does not act on the shaft housing 20 . Therefore, the strength requirements of the shaft housing 20 are relaxed. In particular, since the load on the upper surface side of the shaft support holes 27 and 28 is suppressed, the thickness of the upper surface side of the support blocks 22 and 23 can be reduced, and the size and weight of the shaft housing 20 can be reduced.

Thus, the shaft housing 20 functions as a spacer specialized for directly supporting the rocker shafts 32 (33). Since the fastening bolts 71 and 72 directly tighten and fix the rocker shaft 32 (33), the rocker shaft 32 (33) can be prevented from rattling and supported with high precision. By suppressing rattling of the rocker shafts 32 (33), wear of the inner sides of the shaft support holes 27 and 28 can be prevented. This point also contributes to the reduction in size and weight of the shaft housing 20 .

In addition, since the rocker shaft 32 (33) and the shaft housing 20 are collectively fixed by the fastening bolts 71, 72, fixing work is not troublesome, and excellent assembling efficiency can be obtained.

The rocker shaft 32 (33) is supported and fixed by a pair of shaft support holes 27, 28 and a pair of fastening bolts 71, 72 spaced apart in the axial direction. Therefore, a beam-shaped support structure is provided, which is fixed at both ends, and the support rigidity of the rocker shaft 32 (33) is improved. Since the pair of shaft support holes 27 and 28 support positions near both ends of the rocker shaft 32 (33) in the axial direction, a wide bearing pitch in the axial direction is ensured.

Since the axial bearing pitch for the rocker shaft 32 (33) is wide, the effective support length of the rocker shaft 32 (33) between the support blocks 22 and 23 can be increased. When the effective support length of the rocker shaft 32 (33) is large, the sleeve 41 (51) of the rocker arm 40 (50) can be supported over a long range in the axial direction, and the rocker arm 40 (50) can be supported and operated. Stability can be improved.

In addition, the biasing spring 34 (35) that biases the rocker arm 40 (50) in the axial direction is supported outside the rocker shaft 32 (33), and one end of the biasing spring 34 (35) is supported. It is brought into contact with the axial side surface of the block 22 . That is, the support block 22 is used as a seat surface for receiving the spring. The support block 22 has a larger cross-sectional area (cross-sectional area perpendicular to the axial direction) than the cross-sectional area of the rocker shaft 32 (33) in order to form the shaft support hole 27 as an axially penetrating full-circumference hole. have. Therefore, the axial side surface of the support block 22 exists in the entire circumferential direction surrounding the rocker shaft 32 (33), and the entire end of the biasing spring 34 (35) is attached to the side surface of the support block 22. It is possible to abut against it. As a result, the urging spring 34 (35) can be stably supported with a simple structure, and an appropriate urging force in the axial direction can be applied to the rocker arm 40 (50).

Similarly to the support block 22, the support block 23 also has a wider cross-sectional area than the rocker shaft 32 (33) (with vertical cross-sectional area). Therefore, the axial side surface of the support block 23 exists in the entire circumferential area surrounding the rocker shaft 32 (33), and the end portion of the sleeve 41 (51) can be received by the large area of the support block 23. can.

Oil flow for supplying lubricating oil around the rocker arm 40 (50) using holes (shaft fixing holes 60, 61, fastening holes 62, 63, through holes 64, 65) into which fastening bolts 71, 72 are inserted. A lubricating structure can be efficiently configured with a small number of parts. Since the heads 71b and 72b of the fastening bolts 71 and 72 are used as lids to prevent oil from leaking to the large-diameter openings 60a and 61a, there is no need to attach a separate lid member, which reduces part costs and reduces assembly time. can reduce the time and effort of

Since the heads 71b and 72b of the fastening bolts 71 and 72 are in contact with the flat portions 64a and 65a formed on the rocker shaft 32 (33), the tightening axial force of the fastening bolts 71 and 72 is applied. The stability of the rocker shaft 32 (33) is excellent. In addition, as the fastening bolts 71 and 72, general bolts having flat bottom surfaces of the heads 71b and 72b can be used, and the parts cost can be suppressed.

As described above, according to the rocker shaft support structure of the present embodiment, the rocker shafts 32 and 33 can be held with high precision with a configuration that is easy to produce.

It should be noted that the present invention is not limited to the above embodiments, and can be implemented with various modifications. In the above embodiment, the configuration, control, and the like shown in the accompanying drawings are not limited to this, and can be changed as appropriate within the scope of exhibiting the effects of the present invention. In addition, it is possible to carry out by appropriately modifying the present invention as long as it does not deviate from the scope of the purpose of the present invention.

For example, in the above embodiment, the shaft fixing holes 60 and 61, the fastening holes 62 and 63, and the through holes 64 and 65 are circular holes having cylindrical inner peripheral surfaces. However, with the exception of the internal threads 62a, 63a of the fastening holes 62, 63, it is also possible to set these holes to non-circular cross-sectional shapes. The tightening axial force by the fastening bolts 71 and 72 is a pressing force between the outer peripheral surface of the rocker shaft 32 (33) and the inner peripheral surfaces of the shaft support holes 27 and 28 and between the lower surface 21 and the mounting surface 14. Therefore, the rocker shaft 32 (33) can be supported and fixed without depending on the inner surface shapes of the shaft fixing holes 60, 61, the fastening holes 62, 63, and the through holes 64, 65 (that is, even if they are not circular holes). can be made

In particular, since the shaft housing 20 functions as a spacer, the shaft fixing holes 60 and 61 are designed so as not to interfere with the shaft portions 71a and 72a of the fastening bolts 71 and 72 regardless of whether they are circular holes or non-circular holes. In addition, it is preferable to have a certain amount of clearance.

In the above embodiment, the shaft fixing holes 60, 61, the fastening holes 62, 63, and the through holes 64, 65 are each formed perpendicular to the axial direction of the rocker shaft 32 (33). This makes it possible to firmly fix the rocker shaft 32 (33) and the shaft housing 20 to the cylinder head 10 without generating an extra component of force when tightening the fastening bolts 71 and 72 and applying an axial force. can. There is also the advantage that the supporting structure of the rocker shaft 32 (33) can be made compact. However, it is also possible to apply a configuration in which the direction in which these holes are formed (the direction in which the fastening bolts 71 and 72 are inserted) is slightly inclined from the direction perpendicular to the axial direction of the rocker shaft 32 (33). That is, the direction of forming the shaft fixing holes 60, 61, the fastening holes 62, 63, and the through holes 64, 65 is required to intersect (including perpendicularly) the axial direction of the rocker shaft 32 (33). as long as it satisfies

In the above embodiment, the shaft support holes 27, 28 are circular holes having a cylindrical inner peripheral surface corresponding to the outer peripheral surface of the rocker shaft 32 (33). With this configuration, the support area in the circumferential direction for the rocker shaft 32 (33) can be maximized, and high support accuracy and stability can be obtained. However, it is also possible to make the shaft support holes 27 and 28 non-circular holes in which a part of the inner surface does not contact the rocker shaft 32 (33).

As an example, the shaft support holes 27 and 28 may be square holes. Even with such a square hole, the axial position of the rocker shaft 32 (33) can be determined by contacting and supporting the rocker shaft 32 (33) at three or more points on the inner surface.

Further, of the shaft support holes 27 and 28, the lower half portion that receives the pressing load toward the cylinder head 10 side is a circular hole as in the above embodiment, and the opposite upper half portion is a non-circular hole. may be configured. As described above, since the load in the direction of pulling up the rocker shaft 32 (33) is received by the cylinder head 10 via the fastening bolts 71, 72, the upper half portions of the shaft support holes 27, 28 are square holes. can be selected to reduce the contact area with the rocker shaft 32 (33).

That is, in the present invention, the requirement that the shaft support hole surrounds the entire circumference of the rocker shaft is not limited to the structure in which the entire inner surface of the shaft support hole is in contact with the rocker shaft. is in contact with the rocker shaft intermittently. Even if the inner surface of the shaft support hole intermittently contacts the rocker shaft, the shape of the shaft support hole surrounds the entire circumference of the rocker shaft, ensuring cross-sectional rigidity around the shaft support hole. Therefore, it is possible to obtain the effect of improving the support strength and support accuracy of the rocker shaft.

It is preferable that the shaft housing 20 directly supports the rocker shaft 32 (33) and the cylinder head 10 is fixed by the fastening bolts 71 and 72, as in the above embodiment. However, unlike the above embodiment, it is also possible to select a structure in which fixing members corresponding to the fastening bolts 71 and 72 are directly fixed to a support member corresponding to the shaft housing 20 . Specifically, a portion corresponding to the shaft housing 20 may be formed integrally with the cylinder head 10 .

INDUSTRIAL APPLICABILITY As described above, the present invention has the effect of providing a rocker shaft support structure that has a simple configuration and is excellent in holding the rocker shaft. is useful for engines such as motorcycles that require

10: Cylinder head 13: Support block 20: Shaft housing (support member)
22: Support block (shaft support part)
23: Support block (shaft support part)
27: Shaft support hole 28: Shaft support hole 30: Camshaft 32: Rocker shaft 33: Rocker shaft 34: Biasing spring (biasing member)
35: biasing spring (biasing member)
40: rocker arm 41: sleeve (supported portion)
50: rocker arm 51: sleeve (supported portion)
60: Shaft fixing hole 60a: Large diameter opening 61: Shaft fixing hole 61a: Large diameter opening 62: Fastening hole 62a: Female screw portion 63: Fastening hole 63a: Female screw portion 64: Through hole 64a: Flat portion 65: Through hole 65a: flat portion 66: axial hole 68: oil supply hole 70: positioning pin 71: fastening bolt (fixing member)
71a: Shaft portion 71b: Head 72: Fastening bolt (fixing member)
72a: Shaft 72b: Head

Claims (3)

An internal combustion engine comprising a rocker arm that swings to operate a valve by rotation of a cam supported by a camshaft, and a rocker shaft that swingably supports the rocker arm, wherein the rocker shaft supports the rocker shaft. in the support structure,
a through hole formed in the rocker shaft and penetrating in a direction intersecting with the axial direction at a position different from a supporting portion of the rocker arm in the axial direction in which the rocker shaft extends;
a shaft support hole that is formed in the support member and penetrates in the axial direction to surround and support a partial axial region of the rocker shaft that includes a portion where the through hole is formed;
formed in the support member, extends in a direction intersecting the axial direction and communicates with the shaft support hole, and corresponds to the through hole in a state in which the rocker shaft is inserted and supported in the shaft support hole. a shaft fixing hole located in the
a fastening hole formed in a cylinder head separate from the support member, extending in a direction intersecting the axial direction, and having a threaded portion formed on the inner surface thereof;
a bolt passing through the shaft fixing hole and the through hole and screwed into the threaded portion of the fastening hole to fix both the rocker shaft and the support member to the cylinder head;
with
The bolt has a shaft portion that can be inserted into the shaft fixing hole and the through hole, and a head portion that is larger in diameter than the shaft portion,
the rocker shaft has a flat portion on its outer surface against which the head abuts when fixed by the bolt;
The shaft fixing hole has a large-diameter opening that accommodates the head of the bolt when the head of the bolt comes into contact with the flat portion,
A rocker shaft support structure , wherein an upper surface of the head portion accommodated in the large-diameter opening is positioned below an upper surface of the support member . A plurality of through holes are provided at different positions in the axial direction, a plurality of shaft support holes are provided at different positions in the axial direction, and a plurality of shaft fixing holes are provided at different positions in the axial direction. 2. The rocker shaft support structure according to claim 1 , wherein a plurality of said fastening holes are provided at different positions in said axial direction. The support member includes a pair of shaft support portions having different positions in the axial direction and each having the shaft support hole and the shaft fixing hole,
A supported portion of the rocker arm supported by the rocker shaft is provided at an axial position between the pair of shaft support portions,
3. The apparatus according to claim 2 , wherein an urging member for urging the rocker arm in the axial direction is arranged at an axial position between one of the pair of shaft supporting portions and the supported portion. Rocker shaft support structure.

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