JP2009174412A - Valve train for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a valve train for an internal combustion engine, feeding oil from the base end of a rocker arm to the front end thereof in a simple structure while suppressing deterioration of dynamic characteristic of the rocker arm. <P>SOLUTION: This valve train includes: the first rocker arm 4 having the base end 41 attached to a rocker shaft 2, the front end 42 provided with an abutting portion 23 abutting on the upper end 71 of an intake valve 7, and a roller 13 made to slidably contact with a first cam 11 between the base end 41 and the front end 42; and an oil transport pipe 24 attached to the outside of the first rocker arm 4 in order to close a portion between a main oil passage 19 formed in the rocker shaft 2 and the front end 42 of the first rocker arm 4. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a valve operating mechanism for opening and closing a valve of an internal combustion engine.

  A valve operating mechanism that opens and closes a valve of an internal combustion engine includes a rocker shaft, a rocker arm, a cam, and the like. Some rocker arms have a base end portion swingably attached to a rocker shaft and a contact portion that contacts the upper end portion of the valve on the distal end side. Such a rocker arm is generally called an end pivot type. The end pivot type rocker arm is provided with a slidable contact portion that is slidably contacted with the cam between a base end portion and a distal end portion thereof. In this slidable contact portion, a chip in which a tip that slides into contact with the cam is formed is called a slipper method, and a roller to which a roller that is in rolling contact with the cam is attached is called a roller method.

  Furthermore, some rocker arms are provided with a hydraulic lash adjuster (HLA) at the tip. The HLA automatically adjusts the clearance (valve clearance) between the cam and the upper end of the valve using the hydraulic pressure of the engine. The oil in the flow path formed in the rocker shaft is supplied to the HLA through an oil path formed in the rocker arm main body. Alternatively, even in a valve operating mechanism that does not have an HLA, an oil passage for guiding oil in the rocker shaft to the contact portion is provided in the rocker arm main body in order to reduce friction at the contact portion between the rocker arm and the upper end portion of the valve. Some are formed (for example, refer to Patent Document 1).

Japanese Patent Laid-Open No. 2004-137852

By the way, when the oil path as described above is formed in the end pivot type rocker arm body, there are disadvantages as described in (1) and (2) below, for example.
(1) Since an end pivot type rocker arm has a tip or a roller attached between a base end portion and a tip end portion, an oil passage must be formed avoiding the tip or roller, and design freedom is low. In particular, in the roller type rocker arm, it is substantially impossible to form an oil passage so as to penetrate between the base end portion and the tip end portion in the rocker arm body due to the presence of the roller between the base end portion and the tip end portion. It is almost always possible.
(2) In order to improve the degree of freedom in designing the oil passage, it is conceivable to increase the size of the rocker arm main body and secure the oil passage forming portion in addition to the tip or roller attachment portion. However, when the size of the rocker arm is increased, the weight of the rocker arm increases, so that the inertial mass on the tip side of the rocker arm increases, and the dynamic characteristics of the rocker arm deteriorate.

  Therefore, the present invention has been proposed in view of the above-described problems, and can supply oil from the proximal end side of the rocker arm to the distal end side thereof with a simple structure while suppressing deterioration of the dynamic characteristics of the rocker arm. An object is to provide a valve mechanism for an internal combustion engine.

  In the valve operating mechanism of the internal combustion engine according to the first invention for solving the above-described problem, the base end side is attached to the rocker shaft, and a contact portion that contacts the upper end of the valve is provided on the tip end side. On the outside of the rocker arm so as to connect the rocker arm provided with the sliding contact portion that slides on the cam between the head side and the tip side, the oil passage formed in the rocker shaft, and the tip side of the rocker arm. And an attached oil transportation pipe.

  A valve operating mechanism for an internal combustion engine according to a second invention that solves the above-described problem is a valve operating mechanism for an internal combustion engine according to the first invention, and is provided on the tip end side of the rocker arm to adjust the valve clearance. A clearance adjusting means is provided, and the oil transport pipe supplies lubricating oil in the oil passage of the rocker shaft to the clearance adjusting means.

  A valve operating mechanism for an internal combustion engine according to a third invention for solving the above-described problem is the valve operating mechanism for the internal combustion engine according to the first or second invention, wherein the cam contacts the sliding contact portion of the rocker arm. It is characterized in that a roller is attached.

  A valve operating mechanism for an internal combustion engine according to a fourth invention for solving the above-described problem is the valve operating mechanism for an internal combustion engine according to any one of the first to third inventions, comprising an oil transport pipe, a rocker arm, Is characterized by gradually decreasing from the base end side to the front end side of the rocker arm.

  According to the valve operating mechanism of the internal combustion engine according to the present invention, since the oil transport pipe is attached to the outside of the rocker arm and there is no need to increase the size of the rocker arm, the rocker arm is provided in order to provide an oil passage inside the rocker arm. Compared with the case where the size is increased, it is possible to suppress a decrease in the dynamic characteristics of the rocker arm. Since the oil transport pipe is attached to the outside of the rocker arm, the structure is compared to the case where an oil passage is provided inside the rocker arm so as to avoid a sliding contact portion between the base end side and the tip end side of the rocker arm. It is simple.

  The best mode for carrying out a valve operating mechanism for an internal combustion engine according to the present invention will be specifically described with reference to the drawings.

With reference to FIGS. 1 and 2, the valve operating mechanism for an internal combustion engine according to the present invention is applied to an engine in which a plurality of cylinders are arranged in series along the longitudinal direction of the engine body. explain.
FIG. 1 is a plan view showing a rocker arm provided corresponding to the intake side of one of a plurality of cylinders in a cylinder head of an internal combustion engine having a valve operating mechanism, and FIG. It is an II-II line arrow directional view.

  As shown in FIGS. 1 and 2, the valve mechanism of the internal combustion engine according to the present embodiment includes a rocker shaft 2, a camshaft 3, a rocker arm (first rocker arm 4 and second rocker arm 5), and the like.

  The rocker shaft 2 is attached in the vicinity of the side wall 1a on the intake side of the cylinder head 1 so as to be along the front-rear direction (vertical direction in FIG. 1) of the cylinder head 1. A pair of first rocker arms 4 and a second rocker arm 5 between the first rocker arms 4 are attached to the rocker shaft 2. The set of the first rocker arm 4 and the second rocker arm 5 is attached corresponding to each cylinder of the engine. A main oil passage 19 is formed in the axial center portion of the rocker shaft 2. As shown in FIG. 2, a partition wall 20 is provided in the main oil passage 19. The partition wall 20 constitutes a first main oil passage 19a and a second main oil passage 19b supplied to the pipe 24 from a hydraulic pressure supply mechanism (not shown).

  The camshaft 3 is located on the center side in the width direction of the cylinder head 1 (left side in FIGS. 1 and 2) relative to the rocker shaft 2, and is above the rocker shaft 2 in the height direction (in FIG. 2). (Upper side). The camshaft 3 is disposed on both the intake and exhaust sides of the cylinder head 1, but only the intake side is shown in FIGS. 1 and 2. The camshaft 3 is rotatably supported by the cylinder head 1. A first cam 11 and a second cam 12 are formed on the camshaft 3. The first cam 11 contacts the first rocker arm 4, and the second cam 12 contacts the second rocker arm 5. The second cam 12 has a cam profile that includes the first cam 11 and has a larger lift amount than the first cam 11.

  The first rocker arm 4 has a base end portion 41, a tip end portion 42, and a central portion 43 therebetween. The proximal end portion 41 is attached to the rocker shaft 2, and a central portion 43 extends from the proximal end portion 41, and a distal end portion 42 is formed at the distal end of the central portion 43. In a side view (see FIG. 2), the overall shape of the first rocker arm 4 is substantially U-shaped and opened upward. A first roller 13 that is in rolling contact with the first cam 11 of the rocker shaft 3 is rotatably attached to the central portion 43. The first roller 13 is in sliding contact with the first cam 11 of the camshaft 3 from below.

  The base end portion 41 includes a hole 41a through which the rocker shaft 2 is inserted. An accommodation portion 41b of the coupling mechanism 6 is formed above the hole 41a. The accommodating portion 41 b has a cylindrical space inside, and the upper end thereof is closed by the lid member 32. As will be described in detail later, the connecting mechanism 6 plays a role of switching both the first rocker arm 4 and the second rocker arm 5 to a connected state or a disconnected state.

  The tip portion 42 includes a recess 42a that opens downward. A hydraulic lash adjuster (valve clearance automatic adjusting mechanism, hereinafter referred to as HLA) 22 for adjusting the valve clearance is mounted in the recess 42a. Below the HLA 22, the tip 42 is linked to the intake valve 7.

  The intake valve 7 has a valve head 7a and a valve stem 7b. The intake valve 7 is attached so that the valve stem 7 b slides up and down in the hole 1 b of the cylinder head 1 and the valve head 7 a opens and closes the intake port 8. A valve cap 23 is attached to the upper end portion 71 of the valve stem 7b. Via the valve cap 23, the valve stem 7b and the recess 43a of the first rocker arm 4 (the lower end of the HLA 22) are linked. On the outer periphery of the valve stem 7b, a compressed spring 10 is disposed between the valve seat members 9a and 9b. By this spring 10, the intake valve 7 is normally urged upward to close the intake port 8, and when the valve stem 7b is pushed down by the swing of the first rocker arm 4, the intake port 8 is opened. Is done.

  An oil transport pipe 24 is attached to the lower side outside the first rocker arm 4 so as to connect the base end portion 41 and the tip end portion 42. The oil transport pipe 24 is made of aluminum by way of example, and is lighter than that made of iron. The oil transport pipe 24 has one end 24a and the other end 24b bent in a bowl shape.

  One end 24 a of the oil transport pipe 24 is fixed to a boss 41 c of the base end 41 of the first rocker arm 4. The one end portion 24 a communicates with the oil passage 25 of the base end portion 41. The oil passage 25 communicates with the first main oil passage 19a and the second main oil passage 19b via an oil passage 26 formed in the rocker shaft 2. Accordingly, the one end portion 24a of the oil transport pipe 24 communicates with the first main oil passage 19a and the second main oil passage 19b of the rocker shaft 2.

  The other end 24 b of the oil transport pipe 24 is fixed to the boss 42 c of the tip 42 of the first rocker arm 4. The other end portion 24 b communicates with the oil passages 27 and 28 in the tip end portion 42. The oil passage 27 is formed so as to extend in the up-down direction within the tip portion 42, and the oil passage 28 is formed between the oil passage 27 and the recess 42a (HLA 22). Therefore, the other end 24 b of the oil transport pipe 24 communicates with the HLA 22 (recess 42 a) via the oil passages 27 and 28.

  The pressure oil in the rocker shaft 2 is supplied from the oil passage 26 through the oil passage 25 into the oil transport pipe 24. Then, the pressure oil in the oil transport pipe 24 is supplied to the HLA 22 through the oil passages 27 and 28. Thus, since the pressure oil in the rocker shaft 2 can be supplied to the HLA 22 via the oil transport pipe 24, the smooth operation of the HLA 22 is maintained.

  As shown in FIG. 2, a gap d is secured between the lower end of the first rocker arm 4 and the oil transport pipe 24. This gap d is relatively large on the base end 41 side of the first rocker arm 4 (one end 24a of the oil transport pipe 24), and on the tip end 42 side of the first rocker arm 4 (the other end 24b of the oil transport pipe 24). It is getting smaller gradually toward. In other words, the oil transport pipe 24 extends so that the other end portion 24b side is closer to the first rocker arm 4 than the one end portion 24a side. Therefore, as a whole, the first rocker arm 4 has a smaller inertial mass in the distal end portion 42 than in the base end portion 41, and as a result, the dynamic characteristics of the first rocker arm 4 are not impaired.

  The second rocker arm 5 has a second arm body 52 disposed between the pair of first rocker arms 4 and a T-shaped portion 51 disposed on the base end portion 41 side of the first rocker arm 4. A second roller 31 that is in rolling contact with the second cam 12 of the rocker shaft 3 is attached to the second arm body 52. The second roller 31 is in sliding contact with the second cam 12 of the camshaft 3 from below. Both end portions 5a of the T-shaped portion 51 can be connected to and disconnected from the base end portion 41 of the first rocker arm 4 via the connecting mechanisms 6 provided on the pair of first rocker arms 4 described above.

Here, the connection mechanism 6 will be described.
As clearly shown in FIG. 2, the coupling mechanism 6 includes a piston 15 that is slidably disposed in the accommodating portion 41 b of the base end portion 41 of the first rocker arm 4. A cutout portion 16 is formed on the back side of the housing portion 41b (the side opposite to the camshaft 3). The cutout portion 16 is formed by cutting out a part on the back side of the housing portion 41b into a square shape. The end portion 5 a of the T-shaped portion 51 of the second rocker arm 5 faces the notch portion 16.

  The piston 15 is a columnar member that is in sliding contact with the inner wall of the accommodating portion 41b, and includes a locking step 17 at a part of the upper end. The piston 15 is formed with a hole 15 a for accommodating the return spring 18. The return spring 18 is disposed in a compressed state between the lid member 32 and the hole 15 a of the piston 15. By this return spring 18, the piston 15 is urged downward (side approaching the rocker shaft 2), and the cutout portion 16 is normally open (state shown in FIG. 2). The piston 15 is raised against the urging force of the return spring 18 by pressure oil supplied from an oil passage 21 formed in the rocker shaft 2.

  Assume that the engine is operated in a low speed range. At this time, as described above, the piston 15 is urged downward by the return spring 18 and the notch 16 is opened (a state in which no pressure oil is supplied). In this state, the end portion 5a of the T-shaped portion 51 of the second rocker arm 5 is not locked to the notch 16 of the accommodating portion 41b of the first rocker arm 4, and the second rocker arm 5, the first rocker arm 4 and Are not concatenated. Therefore, the displacement of the second rocker arm 5 is not transmitted to the first rocker arm 4, and the operation of the first rocker arm 4 is transmitted to the intake valve 7.

  On the other hand, it is assumed that the engine is operated in a high speed range. At this time, the pressure oil in the first main oil passage 19a of the rocker shaft 2 is supplied from the oil passage 21 into the accommodating portion 41b. Then, the piston 15 rises against the urging force of the return spring 18, and as the piston 15 rises, the locking step portion 17 is also displaced upward, and the space of the notch portion 16 is reduced. In this state, the end portion 5a of the T-shaped portion 51 of the second rocker arm 5 is pushed from below by the piston 15 at the notch 16 of the accommodating portion 41b of the first rocker arm 4, and the second rocker arm 5 is pushed by the first rocker arm 5. 4 is connected. Therefore, when the second rocker arm 5 swings, the first rocker arm 4 also swings in conjunction with this. As a result, the distal end 42 side of the first rocker arm 4 swings in accordance with the cam profile of the second cam 12. The displacement of the second cam 12 transmitted to the first rocker arm 4 is transmitted to the upper end portion 71 of the valve stem 7b and pushes down the intake valve 7. Therefore, the cam profile of the second cam 12 is transmitted to the intake valve 7 via the second rocker arm 5 and the first rocker arm 4.

  In the valve mechanism as described above, the intake valve 7 is supported by the cylinder head 1, and the intake valve 7 prevents the first rocker arm 4 from moving in the longitudinal direction of the cylinder head (the rocker shaft 2 axis direction). The pair of first rocker arms 4 prevents the second rocker arm 5 from moving in the same direction.

  During the operation of the first and second rocker arms 4 and 5, the pressure oil in the rocker shaft 2 is appropriately supplied to the HLA 22 via the oil transport pipe 24. For this reason, the valve clearance is appropriately adjusted by the HLA 22. As described above, since the oil transport pipe 24 has a structure that is attached to the outside of the first rocker arm 4, it is not necessary to increase the size of the first rocker arm 4, and the oil transport pipe 24 can reduce the weight. Therefore, an increase in the weight of the first rocker arm 4 can be suppressed. Therefore, an increase in the load applied to the intake valve 7 from the first rocker arm 4 can also be suppressed. Therefore, it is necessary to form an oil transport path in the rocker arm, and the operation of the valve system is larger than that in which the rocker arm itself is enlarged. The deterioration of characteristics can be suppressed. That is, the target valve operation is accurately transmitted from the camshaft 3 through the rocker arms 4 and 5 without causing a bounce or jump phenomenon.

  Further, since the oil transport pipe 24 is attached to the outside of the first rocker arm 4, the structure is simpler than the case where the oil transport path is provided inside the first rocker arm. That is, the end roller type first rocker arm 4 described in the present embodiment has the first roller 13 between the base end portion 41 and the tip end portion 42. Therefore, in the first rocker arm 4, it is substantially impossible or impossible to form the oil transport path so as to penetrate from the base end portion 41 to the tip end portion 42. It is extremely difficult. On the other hand, in the structure in which the oil transport pipe 24 is attached to the outside of the first rocker arm 4, it is not necessary to form an oil transport path inside the first rocker arm 4 so as to avoid the first roller 13. Very advantageous.

  In the present embodiment, the example of the valve mechanism having a pair of the first rocker arm 4 and the second rocker arm 5 has been described. However, the valve mechanism has only one pair or one first rocker arm that drives the intake valve. It is also a valve operating mechanism, and it is possible to apply the oil transport pipe 24 described above to the first rocker arm. Further, the first and second rocker arms 4 and 5 can be applied to those using chips instead of rollers.

  The valve operating mechanism of the internal combustion engine according to the present invention can supply the lubricating oil from the base end side of the rocker arm to the front end side thereof with a simple structure while suppressing the deterioration of the dynamic characteristics of the rocker arm. Etc., and can be used very effectively.

1 is a plan view showing a rocker arm provided corresponding to the intake side of one of a plurality of cylinders in a cylinder head of an internal combustion engine having a valve operating mechanism for an internal combustion engine according to a first embodiment of the present invention. is there. It is the II-II arrow directional view in FIG.

Explanation of symbols

2 Rocker shaft 4 First rocker arm 5 Second rocker arm 7 Valve (intake valve)
11 First cam 13 First roller 19 Main oil passage 22 Hydraulic lasher adjuster (HLA)
24 Oil Transport Pipe 41 Base End 42 Front End 43 Center

Claims (4)

The proximal end side is attached to the rocker shaft, the abutting portion that abuts the upper end of the valve is provided on the distal end side, and the slidable contact portion that slidably contacts the cam between the proximal end side and the distal end side is provided. The provided rocker arm,
A valve operating mechanism for an internal combustion engine, comprising: an oil passage formed in the rocker shaft and an oil transport pipe attached to the outside of the rocker arm so as to connect between the rocker arm and the tip end side. A valve operating mechanism for an internal combustion engine according to claim 1,
Provided on the tip end side of the rocker arm, provided with a clearance adjusting means for adjusting the valve clearance,
The valve mechanism for an internal combustion engine, wherein the oil transport pipe supplies lubricating oil in an oil passage of the rocker shaft to the clearance adjusting means. A valve operating mechanism for an internal combustion engine according to claim 1 or 2,
A valve operating mechanism for an internal combustion engine, wherein a roller that is in rolling contact with the cam is attached to a sliding contact portion of the rocker arm. A valve operating mechanism for an internal combustion engine according to any one of claims 1 to 3,
The valve operating mechanism for an internal combustion engine, wherein an interval between the oil transport pipe and the rocker arm gradually decreases from a proximal end side to a distal end side of the rocker arm.

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