JP3985032B2 - Variable valve mechanism - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a variable valve mechanism that changes a valve timing and a lift amount in accordance with an operation state of an internal combustion engine, and particularly relates to a rotation blocking structure of a direct stroke type valve lifter.
[0002]
[Prior art]
According to the variable valve mechanism using a solid cam in which the cam profile continuously changes in the axial direction and a direct hitting valve lifter provided with a cam contact that contacts the solid cam, the internal combustion engine can be operated at a low speed. The valve timing and the lift amount can be continuously changed until high rotation, and precise control according to the operating condition of the internal combustion engine can be performed. In this variable valve mechanism, a rotation prevention structure that prevents the cam contact from rotating with respect to the three-dimensional cam is provided. However, in the rotation prevention structure described in the above publication, an increase in the number of parts, a decrease in rigidity, etc. (Pointed out in JP 2000-136704 A).
[0003]
Accordingly, the applicant of the present invention has previously made a cylinder head 109 as an anti-rotation structure capable of solving the above problem on the outer peripheral surface of the end wall portion 118 of the inverted cup-shaped cup member 107 of the direct hitting valve lifter as shown in FIG. A convex portion 125 that prevents the rotation of the cup member 107 with respect to the groove is integrally provided, and a concave groove 126 into which the convex portion 125 is slidably fitted is provided in a part of the guide hole 110 of the cylinder head 109. Proposed (Japanese Patent Laid-Open No. 2000-136704). According to this variable valve mechanism, the number of parts can be reduced and the rigidity can be increased.
[0004]
[Problems to be solved by the invention]
However, according to the rotation prevention structure of FIG. 7, since the convex portion 125 is provided outside the end wall portion 118, the convex portion 125 becomes an obstacle and it becomes difficult to grind the outer peripheral surface of the side wall portion 119. It has also become difficult to ensure the accuracy.
[0005]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a variable valve mechanism that can realize a rotation prevention structure for a cup member and a cam contact with a simple configuration, and can easily grind the outer peripheral surface of the side wall and ensure accuracy. There is to do.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a variable valve mechanism according to the present invention includes a three-dimensional cam in which a cam profile is continuously changed in the axial direction, and the three-dimensional cam according to an operating condition such as the rotational speed of an internal combustion engine. In a variable valve mechanism comprising a displacement device for displacing in a direction and a direct stroke valve lifter that opens and closes a valve by reciprocating based on a cam profile of the solid cam, the direct stroke valve lifter contacts the solid cam And a cylindrical cup member slidably inserted into the lifter guide hole of the cylinder head, and the side wall that slidably contacts the end wall portion facing the solid cam and the lifter guide hole. A hole formed in the side wall portion, and a protrusion projecting outside the side wall portion through the hole, and a hole that cannot pass through the hole. Mosquito Attaching a rotation preventing member and the attachment portion attached to the inner surface of the flop member, which are integrally formed, wherein the convex portion includes a front plate portion, respectively from both side edges of the front plate portion side plate portion extending rearward, the An upper plate portion extending rearward from the upper end edge of the front plate portion and a positioning portion extending laterally formed at the rear end edge of each side plate portion, the mounting portion being integrated from the rear end edge of the upper plate portion It is formed, and a concave groove is formed in the lifter guide hole of the cylinder head so that the convex portion is slidably fitted.
[0007]
Although it does not specifically limit as said attachment part, The following aspect is illustrated.
(1) A mode in which the cup member is held in position by pressing the inner surface of the side wall.
(2) The aspect comprised so that it might attach by welding and fixing to the said end wall part inner surface.
[0008]
The solid cam is preferably one in which the cam profile is continuously changed in the axial direction from the low rotation cam profile to the high rotation cam profile.
[0009]
The valve timing phase, valve opening angle and lift amount in the low-rotation cam profile, and the valve timing phase, valve opening angle and lift amount in the high-rotation cam profile depend on the requirements of each internal combustion engine. It can be set appropriately. In many cases, however, the low-rotation cam profile has a small valve opening angle and lift, and the high-rotation cam profile has a large valve opening angle and lift.
[0010]
When the three-dimensional cam is displaced stepwise by the displacement device, it may be changed in two steps. In that case, it is preferable that the two-stage displacement can be adjusted. More preferably, the three-dimensional cam is displaced in at least three stages. Most preferably, the three-dimensional cam is continuously displaced. The displacement device is not limited to a specific structure, and examples using hydraulic pressure, electromagnetic force, and the like can be given.
[0011]
The follow-up contact mechanism is not particularly limited, but preferably includes a semi-cylindrical inner surface seat provided at the center of the lifter bridge and a cam contact fitted to the semi-cylindrical inner surface seat so as to allow a roll motion. This cam contactor may be a replacement part for adjusting the valve clearance. In addition, a roller mechanism with a cam contact shown in Japanese Patent Laid-Open No. 9-296714 can be applied.
[0012]
The variable valve mechanism of the present invention can be applied to either the intake valve or the exhaust valve, but is preferably applied to both.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a variable valve mechanism in which the present invention is applied to both an intake valve and an exhaust valve will be described below with reference to the drawings. Therefore, in the embodiment, the term “valve” refers to both an intake valve and an exhaust valve.
[0014]
First, as shown in FIGS. 1 to 4, the camshaft 1 of the variable valve mechanism has a cam profile continuous in the axial direction from the low-rotation cam profile on the right side to the high-rotation cam profile on the left side in FIG. A three-dimensional cam 2 that is changed in an automatic manner is formed. The solid cam 2 is composed of a base circle portion 2a and a nose portion 2b. The base circle portion 2a has the same radius in both the low-rotation cam profile and the high-rotation cam profile, and is a cylindrical surface having no inclination. However, the nose portion 2b is inclined like a conical surface because the valve opening operating angle and the lift amount are small in the low rotation cam profile and the valve opening operating angle and the lift amount are large in the high rotation cam profile. Yes.
[0015]
A displacement device 3 is provided at the end of the camshaft 1 for continuously displacing the camshaft 1 and the three-dimensional cam 2 in the axial direction in accordance with operating conditions such as the rotational speed of the internal combustion engine. The displacement device 3 includes, for example, a guide portion of the camshaft 1 using a spline and a drive portion of the camshaft 1 using a hydraulic pressure (both not shown), and includes an internal combustion engine rotation sensor, an accelerator opening sensor, and the like. It is controlled by a control device (not shown) such as a microcomputer that operates based on the above.
[0016]
Below the camshaft 1, a direct hitting valve lifter 5 that opens and closes the valve 4 based on the cam profile of the three-dimensional cam 2 is disposed. The valve lifter 5 includes a cam contact 6 that contacts the three-dimensional cam 2 and a cylindrical cup member 7 that supports the cam contact 6, and the cup member 7 is biased toward the three-dimensional cam 2 by a spring 8. . The cam contact 6 is formed in a half cylinder, and is swung around an axis perpendicular to the camshaft 1 following the change in the contact line angle accompanying the rotation of the three-dimensional cam 2 (see FIG. 4). The cup member 7 is slidably inserted into the lifter guide hole 10 of the cylinder head 9 and is reciprocated along an axis parallel to the stem portion 4a of the valve 4 via the cam contact 6 as the solid cam 2 rotates. .
[0017]
The stem portion 4 a is slidably inserted into a valve guide 11 fixed to the cylinder head 9. A notch 12 is formed at the upper end of the stem 4a, and a spring retainer 13 is locked to the notch 12 through a cotter 14 so as not to move in the valve axis direction. The spring 8 is fitted into the stem portion 4 a, the upper end thereof is held by the spring retainer 13, and the lower end is held by a spring seat 15 fixed to the cylinder head 9. The spring 8 urges the cup member 7 toward the three-dimensional cam 2 to press the cam contact 6 against the three-dimensional cam 2 and urges the valve 4 in the closing direction. An escape recess 16 (see FIG. 3) is formed on the upper surface of the cylinder head 9 to escape the rotation locus of the solid cam 2.
[0018]
The cup member 7 is integrally formed from an end wall portion 18 that faces the solid cam 2 and a side wall portion 19 that is in sliding contact with the lifter guide hole 10. The upper surface of the end wall 18, that is, the cam-facing surface, is integrally provided with a raised portion 20 that is long in a direction perpendicular to the axis of the camshaft 1. A seat 21 is recessed. The raised portion 20 and the semi-cylindrical inner surface seat 21 constitute a support portion of the cam contact 6, and the cam contact 6 can swing around an axis perpendicular to the camshaft 1 and around the center line of the valve 4. It is supported so that it cannot rotate. Further, in order to restrict the movement of the cam contact 6 in the longitudinal direction, the cam contact 6 is provided with a protrusion 23 that fits into the notch 22 of the end wall portion 18.
[0019]
On the other hand, a recessed groove 26 is formed in the lifter guide hole 10 of the cylinder head 9 so as to extend in the sliding direction of the cup member 7. A hole 27 is provided in the side wall portion 19, and a rotation prevention member 25 that prevents rotation of the cup member 7 relative to the cylinder head 9 is attached through the hole 27. The rotation preventing member 25 is made of a leaf spring material, and is formed so as to be unable to pass through the hole 27 and the convex portion 30 that is inserted into the hole 27 from the inside of the cup member 7 and protrudes to the outside of the side wall portion 19. A mounting portion 31 that is attached to the inner surface is integrally formed.
[0020]
The convex portion 30 includes a front plate portion 35, side plate portions 36 extending rearward from both side edges of the front plate portion 35, and an upper plate portion 37 extending rearward from the upper end edge of the front plate portion 35. Yes. A positioning portion 38 extending in the lateral direction is formed at the rear end edge of each side plate portion 36. The attachment portion 31 includes a base portion 40 that is substantially suspended from the rear end edge of the upper plate portion 37, and a pair of pressing portions that extend rearward from both side edges of the base portion 40 and press the inner peripheral surface of the side wall portion 19. 41. The pressing portion 41 is formed in a substantially arcuate shape so that the outer surface thereof faces substantially along the inner peripheral surface of the side wall portion 19.
[0021]
In order to attach the rotation preventing member 25, the pair of pressing portions 41 are contracted so as to be close to each other, and inserted in the side wall portion 19 in this state. Then, when the protruding portion 30 is protruded to the outside of the side wall portion 19 through the hole 27 and the pressing portion 41 is disposed so as to extend in the circumferential direction of the inner surface of the end wall portion 18, the attachment is completed. At this time, since the pair of side plate portions 36 presses the inner peripheral surface of the hole 27, the protrusion 30 is prevented from coming off from the hole 27. Further, the positioning portion 38 is locked to the inner peripheral surface of the side wall portion 19, whereby the convex portion 30 is positioned with respect to the inner peripheral surface of the side wall portion 19. Further, the pressing portion 41 presses the inner peripheral surface of the side wall portion 19, and the rotation preventing member 25 is held in position by the cup member 7 so as not to come out of the cup member 7.
[0022]
According to the variable valve mechanism configured as described above, the following effects can be obtained.
(1) Since a separate rotation prevention member 25 is attached to the cup member 7 in which the raised portion 20 and the semi-cylindrical inner surface seat 21 which are the support portions of the cam contactor 6 are integrally provided, A conventional convex portion need not be provided on the outside of the wall portion 18, the outer peripheral surface of the side wall portion 19 can be easily ground, and the accuracy of the surface can be easily ensured.
[0023]
(2) Since the mounting portion 31 is configured to be held in position by the cup member 7 by pressing the inner surface of the side wall portion 19, there is no need for fixing work such as welding to the cup member 7. It is easy to work with.
[0024]
Next, FIG.5 and FIG.6 shows the example of a change of a rotation prevention member. The rotation preventing member 50, the mounting portion 51, the upper surface is formed to extend in an arc shape on both sides from the edge after the upper plate portion 37 so as to face the end wall portion 18 the inner surface, the distal end 51a Is different from the above-described embodiment in that it is attached to the inner surface of the end wall portion 18 by welding, and the others are substantially common. In addition, it is preferable that welding is a part with little heat influence to the cup member 7 like the part 52 shown, for example in FIG. Also in this embodiment, the effect of the circle 1 can be obtained as in the above embodiment.
[0025]
Note that the present invention is not limited to the above-described embodiment, and can be embodied by appropriately changing the configuration / shape of the rotation prevention member and the configuration / shape of other parts without departing from the spirit of the invention. .
[0026]
【The invention's effect】
Since the variable valve mechanism of the present invention is configured as described above, the rotation prevention structure for the cup member and the cam contact can be realized with a simple configuration, and the outer peripheral surface of the side wall is ground and accuracy is ensured. The protrusion of the rotation preventing member can be prevented from coming out of the hole in the side wall, and the protrusion is positioned with respect to the inner peripheral surface of the side wall .
[Brief description of the drawings]
FIG. 1 is a perspective view showing a variable valve mechanism according to an embodiment of the present invention.
FIG. 2 is an exploded perspective view of a direct striking valve lifter of the variable valve mechanism.
3A is a plan view showing a rotation blocking member of the direct hitting valve lifter, FIG. 3B is a plan sectional view showing a state in which the rotation blocking member is attached to a cup member, and FIG. It is a top view of a hitting type valve lifter.
FIG. 4 is a sectional view of the variable valve mechanism.
FIG. 5 is a perspective view showing a modified example of the direct hitting valve lifter.
6A is a perspective view showing a rotation blocking member of a modified example of the direct hitting valve lifter, FIG. 6B is a plan view of the rotation blocking member, and FIG. 6C is a modified example of the direct hitting valve lifter. It is sectional drawing.
FIG. 7 is a perspective view showing a conventional variable valve mechanism.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Cam shaft 2 Three-dimensional cam 3 Displacement device 4 Valve 5 Direct hitting type valve lifter 6 Cam contactor 7 Cup member 8 Spring 9 Cylinder head 10 Lifter guide hole 18 End wall part 19 Side wall part 20 Raised part 21 Semi-cylindrical inner surface seat 25 Rotation prevention Member 26 concave groove 27 hole 30 convex portion 31 attachment portion 41 pressing portion 50 rotation prevention member 51 attachment portion

Claims (3)

A reciprocating motion based on a cam profile of a solid cam in which the cam profile is continuously changed in the axial direction, a displacement device for displacing the solid cam in the axial direction in accordance with an operating condition such as the rotational speed of the internal combustion engine, and the like. In a variable valve mechanism with a direct-acting valve lifter that opens and closes a valve by moving,
The direct hitting valve lifter (5) includes a cylindrical cup inserted in a slidable manner into a cam contact (6) that contacts the three-dimensional cam (2) and a lifter guide hole (10) of the cylinder head (9). A member (7),
The cup member is integrally formed from an end wall portion (18) opposed to the three-dimensional cam and a side wall portion (19) slidably contacting the lifter guide hole, and a hole (27) is formed through the side wall portion,
A convex part (30) projecting to the outside of the side wall part through the hole and an attachment part (31, 51) formed so as not to pass through the hole and attached to the inner surface of the cup member. And a rotation prevention member (25, 50) formed integrally with
The convex portion (30) includes a front plate portion (35), a side plate portion (36) extending rearward from both side edges of the front plate portion, and an upper plate portion extending rearward from the upper end edge of the front plate portion. (37) and a laterally extending positioning portion (38) formed at the rear edge of each side plate portion, and the attachment portions (31, 51) are arranged from the rear edge of the upper plate portion (37). Is formed as one piece,
A variable valve mechanism, wherein a concave groove (26) is formed in the lifter guide hole of the cylinder head so that the convex portion is slidably fitted therein.   The variable valve mechanism according to claim 1, wherein the mounting portion is configured to be held by the cup member by pressing the inner surface of the side wall portion.   The variable valve mechanism according to claim 1, wherein the attachment portion is attached by being welded and fixed to the inner surface of the end wall portion.

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