JP2007085293A - Valve gear for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a valve gear using an end pivot type rocker arm compact in a vertical direction. <P>SOLUTION: The valve gear adopts the end pivot type rocker arm 11 whose one end has a fulcrum of vibration and the other end has a part to be abutted with a valve 5 and an intermediate part has a roller 15. The valve 5 is driven by a cam 12 disposed on the rocker arm 11. The rocker arm 11 has a cross-section of an approximately inverted-U shape whose bottom is opened and which is formed of both side walls 21, 21 in parallel with each other and an upper face wall 22 connecting upper edges of the both side walls 21, 21. Further, the rocker arm is curved so that the shape of a whole rocker arm is projected downward when veiwed from a side, and the lower surface of the upper wall 22 is a face to be abutted with a valve 5. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

    The present invention relates to an engine valve gear.

In recent years, in engines used for vehicles and the like, the energy environment has become severe, and various mechanical resistances have been reduced to improve fuel efficiency. In valve trains, the adoption of so-called end pivot type rocker arms, in which the sliding resistance between the cam nose of the camshaft and the rocker arm is reduced by a roller follower, is increasing. Such valve gears are described in Patent Documents 1 and 2, for example. In addition, the rocker arm has a shape in which the left and right side walls are connected by a connecting wall in order to ensure the strength while reducing the weight, and the left and right side walls and the connecting wall are in contact with the valve shaft. An H-shaped cross section is formed (see Patent Documents 1 and 2).
Japanese Patent Laid-Open No. 11-210417 JP 2001-129633 A

    By the way, in the above-mentioned end pivot type rocker arm, since the rocker arm is disposed between the valve shaft and the camshaft, the height of the cylinder head becomes large and the engine body tends to be enlarged. This may cause inconvenience in mounting the engine on the vehicle body.

    In view of the above, the present invention aims to make the valve system more compact in the vertical direction by devising the structure of the rocker arm.

    In order to solve such problems, the present invention curved the rocker arm so that the entire rocker arm protrudes downward in a side view, and has a U-shaped cross section in which the lower part is abutted against the valve shaft. .

The invention according to claim 1 is provided with an end pivot type rocker arm having a swing fulcrum at one end, a roller follower in the middle, and the other end abutting the valve, and a valve shaft arranged in the vertical direction. A valve operating device for an engine driven by a cam disposed above a rocker arm,
The rocker arm is formed in a substantially U-shaped cross-section with a lower side opened by both side walls parallel to each other and an upper wall connecting the upper edges of both side walls. It curves so that it may become convex, and the lower surface of the upper surface wall of the said other end is formed in the valve contact surface which contacts the end of a valve shaft, It is characterized by the above-mentioned.

    That is, the rocker arm is curved so that the whole is convex downward in a side view, and the lower surface of the upper wall connecting both side walls on the upper side is a valve contact surface, so that the roller position of the roller follower can be kept low. Become. Therefore, although the rocker arm is arranged between the valve shaft and the camshaft, the height difference between the valve shaft and the camshaft is not increased, and the valve system is made compact in the vertical direction, and the engine is This is advantageous for making the direction compact.

The invention according to claim 2 is the invention according to claim 1,
The rocker arm is in a closed state so that the center of the roller of the roller follower lies on a straight line connecting the swing center of the end pivot and the contact point of the other end with respect to the end of the valve shaft, or It is curved so as to exist below the straight line.

    Therefore, the roller position can be lowered by such a curvature, which is advantageous for the above-described compactness.

The invention according to claim 3 is the invention according to claim 1 or claim 2,
The end pivot is constituted by a pivot member and a pivot receiving member,
The pivot member has a shaft portion at the upper portion and a pivot portion at the lower portion, and the shaft portion penetrates the upper surface wall of one end of the rocker arm and is fixed to the upper surface wall by an adjuster nut.
The pivot receiving member is provided on the cylinder head side, and has a pivot receiving surface that is curved so as to protrude downward to receive the pivot portion.
An axis line connecting the center of the pivot receiving surface and the swing center of the pivot portion is inclined so that the upper side is away from the valve shaft and the lower side is closer to the valve shaft.

    That is, when the nose of the cam rotates and moves from the end pivot side to the valve side, when the rocker arm is pushed down in the valve opening direction, a substantially lateral force toward the valve side acts on the end pivot, The force is a force that lifts the pivot portion from the pivot receiving surface. On the other hand, in the present invention, the axis of the pivot receiving surface is inclined as described above, and the upper edge of the receiving surface on the valve shaft side is located above the upper edge on the opposite side. Therefore, the substantially lateral force acting on the end pivot is reliably received by the valve shaft side portion of the pivot receiving surface, and as a result, the pivot portion is prevented from being lifted due to the lateral force.

According to a fourth aspect of the present invention, in any one of the first to third aspects,
The roller of the roller follower faces upward from the opening formed in the upper surface wall,
An oil jet opening communicating with an oil passage passing through the shaft portion of the cam is opened on a peripheral surface of the base circle portion of the cam.

    Therefore, without providing an oil gallery in the cylinder head, the oil can be lubricated by the oil passage that passes through the shaft portion of the cam, which is advantageous in simplifying the structure of the cylinder head.

The invention according to claim 5 is any one of claims 1 to 4,
The engine is a direct-injection diesel engine having an intake valve and an exhaust valve standing upright so that each valve shaft is parallel to a cylinder center line.

    Therefore, according to the present invention, a direct injection diesel engine whose vertical dimension tends to be large due to the upright intake / exhaust valves as described above is advantageous for downsizing the valve system, and thus the engine as a whole. .

    As described above, according to the present invention, in the end pivot type rocker arm having the roller follower, the rocker arm is lowered by the side walls parallel to each other and the upper wall connecting the upper edges of the side walls. Is formed in a substantially U-shaped cross section with an open cross section, and is curved so that the whole is convex downward in a side view, and the lower surface of the upper wall is formed on the valve contact surface. Although the rocker arm is arranged between the shaft and the cam valve shaft and the camshaft, the height difference between the cam valve shaft and the camshaft is not increased. Become advantageous.

    Hereinafter, embodiments of the present invention will be described with reference to the drawings.

    FIG. 1 shows a cylinder head 1 of a multi-cylinder in-cylinder direct injection diesel engine according to an embodiment of the present invention. In the figure, 2 is a cylinder, 3 is an intake port opened to the cylinder 2, and 4 is an exhaust port, each having an intake valve 5 and an exhaust valve 6. The intake valve 5 and the exhaust valve 6 stand upright so that the valve shafts 5a, 6a are parallel to the cylinder center line, and are provided by a coil spring 8 provided between the spring receiver at the valve shaft end and the cylinder head 1. It is urged to close the intake and exhaust ports. Above these valves 5 and 6, a DOHC (double overhead cam) type valve gear is provided.

    An end pivot type rocker arm 11 is employed in the valve operating device, and this rocker arm 11 is provided between the valve shafts 5 a and 6 a and the cam 12 of the camshaft 10. That is, the rocker arm 11 has one end (side away from the cylinder center) supported by the cylinder head 1 by the end pivot 13 and the valve contact portion 14 that contacts the end surfaces of the valve shafts 5a and 6a at the other end (near the cylinder center). The roller 15 which contacts the cam 12 is provided in the middle. The end pivot 13 includes a pivot member 16 fixed to the rocker arm 11 and a pivot receiving member 17 fixed to the cylinder head 1.

    Hereinafter, the valve gear will be described in detail. As shown in FIGS. 2 and 3, the rocker arm 11 has a U-shaped cross section whose lower side is opened by left and right side walls 21 and 21 and an upper surface wall 22 that connects upper edges of the side walls 21 and 21. It is formed in a shape and is curved so as to be convex downward in a side view. An opening 23 is formed in the middle portion of the top wall 22, and the roller 15 is disposed at the position of the opening 23. That is, as shown in FIG. 4, the roller 15 is rotatably supported by the side walls 21 and 21 by the shaft 24, and the upper portion of the roller 15 faces above the opening 23. As shown in FIG. 5, the valve contact portion 14 is formed on the valve contact surface 14a in which the lower surface of the upper surface wall 22 between the side walls 21 and 21 contacts the end surfaces of the valve shafts 5a and 6a. As shown in FIG. 3, the valve contact surface 14a warps as it goes to the end of the rocker arm 11, and as a result, is curved so as to be slightly convex downward.

    As shown in FIG. 3, the pivot member 16 constituting the end pivot 13 includes an upper screw shaft portion 16a and a lower pivot portion 16b. The pivot portion 16b is formed in a curved surface so that the lower surface thereof is a spherical convex shape, and the top surface is formed flat. The screw shaft portion 16 a is screwed from below into a screw hole formed in the upper surface wall 22 of the rocker arm 11 and protrudes upward. As shown in FIG. 1, the pivot member 16 is fixed to the upper surface wall 22 of the rocker arm 11 by applying an adjuster nut 25 to the protruding portion of the screw shaft portion 16 a.

    The point that the rocker arm 11 is curved so as to be convex downward as viewed from the side will be described. As shown in FIG. 6, the rocker arm 11 basically connects the center A of the portion that supports the pivot member 16 and the contact point of the valve contact surface 14a with the valve shafts 5a and 5b in the closed state. It is curved downward so that the center C of the roller 15 is located below the straight line L1. Further, in the present embodiment, the rocker arm 11 is moved downward so that the center C of the roller 15 is located below the straight line L2 connecting the swing center B of the pivot portion 16b and the contact point of the valve contact surface 14a. It is curved.

    On the other hand, as shown in FIG. 1, the pivot receiving member 17 constituting the end pivot 13 is a bolt-shaped member composed of a screw portion and a head portion. Then, the threaded portion is screwed into the cylinder head 1 and fixed, and a pivot receiving surface 17a curved so as to protrude downward is formed on the top surface of the head.

    The pivot receiving surface 17a is formed in a hemispherical shape, and an axis L connecting the center of the pivot receiving surface and the swing center of the end pivot 13 (point B in FIG. 6) is on the upper side of the valve shaft 5a, It inclines so that it may leave | separate from 6a and the lower side may approach the said valve shafts 5a and 6a. This axis coincides with the axis of the pivot receiving member 17. Further, the axis of the pivot member 16 fixed to the rocker arm 11 is similarly inclined corresponding to the inclination of the axis.

    As shown in FIG. 1, the camshaft 10 is formed with an oil passage 26 extending axially in the axial direction, and the cam 12 communicates with the oil passage 26 and opens to the peripheral surface of the base circle portion. An oil jet 27 is formed.

    The intake-side and exhaust-side camshafts 10 rotate counterclockwise in FIG. 1 via a timing chain by a crankshaft of the engine 1. Therefore, on the intake valve side (left side in FIG. 1), when the nose of the cam 12 rotates from the end pivot side to the valve side, the rocker arm 11 is pushed down in the valve opening direction, and the exhaust side (in FIG. 1). On the right side, when the nose of the cam 12 rotates from the valve side to the end pivot side, the rocker arm 11 is pushed down in the valve opening direction.

    As described above, according to the present embodiment, the rocker arm 11 is curved between the valve shafts 5a and 6a and the camshaft 10 because the rocker arm 11 is curved so as to protrude downward as viewed from the side. Although the structure is such that the position of the roller 15 is kept low, the valve operating device becomes compact in the vertical direction. In particular, the cross-sectional shape of the rocker arm 11 is a U-shape in which the upper edges of the side walls 21 and 21 are connected by the upper surface wall 22, and the lower surface of the upper surface wall 22 is the valve contact surface 14 a in the valve contact portion 14. The positioning of the center C of the roller 15 below the straight line L2 connecting the swing center B of the end pivot and the contact point of the valve contact surface 14a works effectively for downsizing in the vertical direction. 1 is advantageous for downsizing in the vertical direction.

    Further, with respect to the intake valve side, when the nose of the cam 12 rotates and moves from the end pivot side to the valve side, a substantially lateral force acting toward the valve side acts on the end pivot 13, and the force is the pivot portion 16b. Is lifted from the pivot receiving surface 17a. In contrast, in the present invention, the axis of the hemispherical pivot receiving surface 17a is inclined as described above, and the upper edge of the receiving surface 17a on the valve shaft 5a side is located above the upper edge on the opposite side. ing. Accordingly, the substantially lateral force acting on the end pivot 13 is reliably received by the valve shaft side surface of the pivot receiving surface 17a, and as a result, the pivot portion 16b is prevented from being lifted due to the lateral force. Is done.

    In the case of the above embodiment, the oil in the oil passage 26 that passes through the axis of the camshaft 10 is supplied to the roller 15 from the oil outlet 17 that is opened in the peripheral surface of the base circle portion of the cam 12. As a result, the roller 15 can be lubricated, and the cylinder head 1 does not have to be provided with an oil gallery for the lubrication, which is advantageous in simplifying the structure of the cylinder head 1.

  The present invention is not limited to a DOHC direct injection diesel engine. For example, it can be applied to a SOHC engine.

  Further, the pivot receiving member 17 of the end pivot 13 may be disposed while being inclined, while the pivot member 16 may not be inclined.

It is sectional drawing of the cylinder head part of an engine. It is a top view of a rocker arm. It is a longitudinal cross-sectional view of a rocker arm. It is a cross-sectional view of the roller part of a rocker arm. It is a cross-sectional view of the valve contact portion of the rocker arm. It is a side view of a rocker arm.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylinder head 2 Cylinder 5 Intake valve 6 Exhaust valve 11 Rocker arm 12 Cam 13 End pivot 14 Valve contact part 14a Valve contact surface 15 Roller 16 Pivot member 16a Shaft part 16b Pivot part 17 Pivot receiving member 17a Pivot receiving surface 21 Side wall 22 Upper surface Wall 23 Opening 25 Adjuster nut 26 Oil passage 27 Oil outlet

Claims (5)

An end pivot type rocker arm with a swing fulcrum at one end and a roller follower in the middle and the other end in contact with the valve, and a valve with a valve shaft arranged in the vertical direction was arranged above the rocker arm A valve operating device for an engine driven by a cam,
The rocker arm is formed in a substantially U-shaped cross section with its lower part opened by both side walls parallel to each other and an upper surface wall connecting the upper edges of the both side walls, and the whole is downward in side view. A valve operating apparatus for an engine, wherein the valve operating surface is curved so as to be convex, and the lower surface of the upper surface wall of the other end is formed on a valve contact surface that contacts the end of the valve shaft. In claim 1,
The rocker arm is in a closed state so that the center of the roller of the roller follower lies on a straight line connecting the swing center of the end pivot and the contact point of the other end with respect to the end of the valve shaft, or A valve operating apparatus for an engine, which is curved so as to exist below the straight line. In claim 1 or claim 2,
The end pivot is constituted by a pivot member and a pivot receiving member,
The pivot member has a shaft portion at the upper portion and a pivot portion at the lower portion, and the shaft portion passes through the upper surface wall of one end of the rocker arm and is fixed to the upper surface wall by an adjuster nut.
The pivot receiving member is provided on the cylinder head side, and has a pivot receiving surface that is curved so as to protrude downward for receiving the pivot portion.
An engine valve operating system characterized in that an axis connecting the center of the pivot receiving surface and the swing center of the pivot portion is inclined such that the upper side is away from the valve shaft and the lower side is closer to the valve shaft. . In any one of Claim 1 thru | or 3,
The roller of the roller follower faces upward from the opening formed in the upper surface wall,
An engine valve operating system characterized in that an oil jet opening communicating with an oil passage passing through a shaft portion of the cam is opened on a peripheral surface of a base circle portion of the cam. In any one of Claims 1 thru | or 4,
The engine valve operating system according to claim 1, wherein the engine is a direct injection diesel engine having an intake valve and an exhaust valve standing upright so that each valve shaft is parallel to a cylinder center line.

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