JP2003184514A - Variable valve mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a rotation prevention structure of a cup member and a cam contact with simple constitution. <P>SOLUTION: A variable valve mechanism includes a solid cam 2 and a direct- push type valve lifter 5. The valve lifter 5 includes the cam contact 6 and the cup member 7. In the cup member 7, an end wall portion 18 in opposite to the solid cam 2 and a side wall portion 19 which comes in sliding contact with a lifter guide hole 10 are formed integrally with each other. The end wall portion 18 is provided with a support portion which supports the cam contact 6 in such a manner that it can swingingly move around an axis perpendicular to a cam shaft 1 and cannot rotate around a center axis of a valve 4. The side wall portion 19 is provided with a hole 27 extending therethrough. The cup member 7 is provided with a rotation prevention member 25 integrally formed with a protrusion 30 which projects to the outside of the side wall portion 19 via the hole 27 and an attachment portion 31 attached to an inner surface of the cum member 7. The lifter guide hole 10 is provided with a concave groove 26 in which the protrusion 30 is fitted in a slidable manner. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable valve mechanism that changes valve timing and lift according to operating conditions of an internal combustion engine, and more particularly to a rotation preventing structure for a direct drive valve lifter.

[0002]

2. Description of the Related Art A variable valve mechanism using a three-dimensional cam whose cam profile changes continuously in the axial direction and a direct-acting valve lifter provided with a cam contactor contacting the three-dimensional cam is an internal combustion engine. It is possible to continuously change the valve timing and the lift amount from the low rotation speed to the high rotation speed, and perform precise control according to the operating condition of the internal combustion engine.
This variable valve mechanism is provided with a rotation blocking structure that prevents the cam contactor from rotating with respect to the three-dimensional cam. However, in the rotation blocking structure described in the above publication, the number of parts is increased and the rigidity is lowered. There was a problem of
No. 00-136704, pointed out).

Therefore, the present applicant has previously proposed, as a rotation preventing structure capable of solving the above problems, as shown in FIG. 18, 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. A convex portion 125 that prevents rotation of the cup member 107 with respect to the cylinder head 109 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. It has been 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]

However, according to the rotation preventing structure of FIG. 7, since the convex portion 125 is provided outside the end wall portion 118, the convex portion 125 interferes with the side wall portion 119.
It became difficult to grind the outer peripheral surface of the, and it was also difficult to secure the accuracy of the surface.

Therefore, an object of the present invention is to provide a variable valve which can realize a rotation preventing structure for a cup member and a cam contactor with a simple structure, and can easily grind an outer peripheral surface of a side wall portion and secure accuracy. To provide a mechanism.

[0006]

In order to achieve the above object, a variable valve mechanism according to the present invention comprises a three-dimensional cam whose cam profile is continuously changed in the axial direction and an operation such as the rotational speed of an internal combustion engine. A variable valve mechanism including a displacement device for axially displacing the solid cam depending on the situation, and a direct-acting valve lifter for opening and closing the valve by reciprocating based on the cam profile of the solid cam, wherein The striking valve lifter includes a cam contactor that comes into contact with the solid cam and a cylindrical cup member that is slidably inserted into a lifter guide hole of a cylinder head. The cup member has an end wall facing the solid cam. Part and a side wall part that is in sliding contact with the lifter guide hole, and a hole is formed through the side wall part, and the cup member has a convex part protruding to the outside of the side wall part through the hole, and the hole. To A recessed groove that is formed so as not to be improper and has a rotation preventing member integrally formed with a mounting portion that is mounted on the inner surface of the cup member, and in which the convex portion is slidably fitted in a lifter guide hole of a cylinder head. Is formed.

The mounting portion is not particularly limited, but the following modes are exemplified. (1) A mode in which the inner surface of the side wall portion is pressed to be held in position by the cup member. (2) A mode configured to be attached by being welded and fixed to the inner surface of the end wall portion.

The three-dimensional 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.

The phase of the valve timing, the valve operating angle and the lift amount in the cam profile for low rotation, and the phase of the valve timing in the cam profile for high rotation,
The valve opening operating angle and the lift amount can be appropriately set according to the requirements of each internal combustion engine. However,
In many cases, the low rotation cam profile has a small valve opening angle and lift amount, and the high rotation cam profile has a large valve opening angle and lift amount.

When the three-dimensional cam is displaced stepwise by the displacement device, it may be changed in two steps, but in that case, it is preferable to be able to adjust the displacement in two steps. More preferably, the solid cam is displaced in at least three steps. Most preferably, the solid cam is continuously displaced. The displacement device is not limited to a specific structure, and may be one using hydraulic pressure, electromagnetic force, or the like.

The follow-up contact mechanism is not particularly limited, but is composed of a semi-cylindrical inner surface seat provided in the central portion of the lifter bridge and a cam contactor fitted to the semi-cylindrical inner surface seat so as to be able to roll. preferable. The cam contact may be a replacement part for adjusting the valve clearance. In addition, the roller mechanism with cam contactor shown in Japanese Patent Laid-Open No. 9-296714 can be applied.

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]

BEST MODE FOR CARRYING OUT 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” simply means both the intake valve and the exhaust valve.

First, as shown in FIGS. 1 to 4, the camshaft 1 of the variable valve mechanism has a cam profile from a low rotation cam profile on the right side to a high rotation cam profile on the left side in FIG. A three-dimensional cam 2 that is continuously changed in the direction is formed. The three-dimensional cam 2 includes a base circle portion 2a and a nose portion 2b, and the base circle portion 2a is
Since the low-rotation cam profile and the high-rotation cam profile have the same radius, they are cylindrical surfaces without inclination. However, the nose portion 2b is inclined like a conical surface because the valve opening working angle and the lift amount are small in the low rotation cam profile and the valve opening working angle and the lift amount are large in the high rotation cam profile. There is.

At the end of the camshaft 1, there is provided a displacement device 3 for continuously displacing the camshaft 1 and the solid cam 2 in the axial direction according to the operating conditions such as the number of revolutions 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 hydraulic pressure (all are not shown), and a rotation sensor of an internal combustion engine, an accelerator opening sensor, etc. Is controlled by a control device (not shown) such as a microcomputer that operates based on the above.

Below the camshaft 1, a direct-acting valve lifter 5 for opening and closing the valve 4 based on the cam profile of the three-dimensional cam 2 is arranged. This valve lifter 5
Includes a cam contactor 6 that contacts the three-dimensional cam 2 and a cylindrical cup member 7 that supports the cam contactor 6, and the cup member 7 is biased toward the three-dimensional cam 2 side by a spring 8.
The cam contactor 6 is formed in a half-cylindrical shape, and follows the change of the contact line angle due to the rotation of the three-dimensional cam 2 and the camshaft 1
Is swung about an axis perpendicular to (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 the axis parallel to the stem portion 4a of the valve 4 via the cam contactor 6 as the solid cam 2 rotates. .

The stem portion 4a 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 portion 4a, and a spring retainer 13 is fixed to the notch 12 via a cotter 14 so as to be immovable in the valve axial direction. The spring 8 is fitted and inserted into the stem portion 4 a, the upper end thereof is held by the spring retainer 13, and the lower end thereof is held by the spring seat 15 fixed to the cylinder head 9. The spring 8 biases the cup member 7 toward the solid cam 2 to press the cam contactor 6 against the solid cam 2 and bias the valve 4 in the closing direction. The upper surface of the cylinder head 9 has a three-dimensional cam 2
Relief recess 16 (see FIG. 3) for releasing the rotation locus of
Are formed.

The cup member 7 is integrally formed from an end wall portion 18 facing the three-dimensional cam 2 and a side wall portion 19 slidingly contacting the lifter guide hole 10. On the upper surface of the end wall portion 18, that is, on the cam facing surface, a ridge 20 that is long in a direction perpendicular to the axis of the cam shaft 1 is integrally provided, and the ridge 20 has a semi-cylindrical inner surface on which the cam contact 6 is seated. The seat 21 is recessed. The raised portion 20 and the semi-cylindrical inner surface seat 21 form a support portion for the cam contactor 6, and the cam contactor 6 can swing around the axis perpendicular to the camshaft 1 and around the centerline of the valve 4 on this support portion. It is supported so that it cannot rotate. Further, in order to regulate the movement of the cam contactor 6 in the longitudinal direction, the cam contactor 6 is
Is provided with a protrusion 23 that fits into the notch 22 of the end wall portion 18.

On the other hand, a 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 formed through the side wall portion 19, and a rotation blocking member 25 that blocks rotation of the cup member 7 with respect 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 not to be able to pass through the convex portion 30 which is inserted into the hole 27 from the inside of the cup member 7 and projects to the outside of the side wall portion 19, and the cup member 7. The mounting portion 31 mounted on the inner surface of the is integrally formed.

The convex portion 30 includes a front plate portion 35 and the front plate portion 35.
Side plate portions 36 extending rearward from both side edges of the front plate portion 35 and upper plate portions 37 extending rearward from the upper edge of the front plate portion 35. A positioning portion 38 that extends laterally is formed at the rear end edge of each side plate portion 36. The mounting portion 31 is the upper plate portion 3.
7, a base portion 40 substantially hanging from the rear end edge, and a pair of pressing portions 41 extending rearward from both side end edges of the base portion 40 and pressing the inner peripheral surface of the side wall portion 19. Pressing part 4
1 is bent and formed in a substantially arcuate shape so that its outer surface faces substantially along the inner peripheral surface of the side wall portion 19.

To attach the rotation preventing member 25,
The pair of pressing portions 41 are contracted so as to be close to each other, and in this state, they are inserted inside the side wall portion 19. Then, the protrusion 30 is projected through the hole 27 to the outside of the side wall portion 19, and the pressing portion 41 is arranged so as to extend in the circumferential direction of the inner surface of the end wall portion 18, whereby the attachment is completed. At this time, since the pair of side plate portions 36 press the inner peripheral surface of the hole 27, the convex portion 3
The zero hole 27 is prevented from coming off. 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 blocking member 25 is held in position by the cup member 7 so as not to come off from the cup member 7.

According to the variable valve mechanism constructed as described above, the following effects can be obtained. Since the rotation preventing member 25 which is a separate body is attached to the cup member 7 integrally provided with the raised portion 20 which is the support portion of the cam contactor 6 and the semi-cylindrical inner surface seat 21, the end wall portion 18 is provided. It is not necessary to provide a convex portion like that in the conventional case on the outside of the, and the outer peripheral surface of the side wall portion 19 can be easily ground,
It also becomes easy to ensure the accuracy of the surface.

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, and it is simple. It can be assembled to and has good workability.

Next, FIGS. 5 and 6 show a modification of the rotation blocking member. The rotation preventing member 50 has a mounting portion 51 formed so as to extend in an arc shape from the leading edge of the upper plate portion 37 to both sides so that the upper surface thereof faces the inner surface of the end wall portion 18, and the leading end portion 51 a is formed. The present embodiment is different from the above embodiment in that it is attached to the inner surface of the end wall portion 18 by welding and fixing, and other points are substantially common. In addition, it is preferable that the welding is performed on a portion having a small thermal influence on the cup member 7, such as a portion 52 shown in FIG. According to the present embodiment, the above effects can be obtained as in the above embodiment.

The present invention is not limited to the above-described embodiment, and is embodied by appropriately changing the configuration and shape of the rotation blocking member and the configuration and shape of other parts without departing from the spirit of the invention. You can also

[0026]

Since the variable valve mechanism of the present invention is configured as described above, the rotation preventing structure for the cup member and the cam contactor can be realized with a simple structure, and the outer peripheral surface of the side wall portion can be realized. It has an excellent effect of facilitating grinding and ensuring accuracy.

[Brief description of 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 drive type valve lifter of the variable valve mechanism.

FIG. 3A is a plan view showing a rotation blocking member of the direct hitting type valve lifter, FIG. 3B is a plan sectional view showing a state where the rotation blocking member is attached to the cup member, and FIG. It is a top view of a hammering 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 type valve lifter.

6A is a perspective view showing a rotation preventing member of a modification of the direct-acting valve lifter, FIG. 6B is a plan view of the rotation preventing member, and FIG. 6C is a modification of the direct-acting valve lifter. FIG.

FIG. 7 is a perspective view showing a conventional variable valve mechanism.

[Explanation of symbols]

1 camshaft 2 three-dimensional cam 3 Displacement device 4 valves 5 Direct hit type valve lifter 6 Cam contactor 7 cup members 8 springs 9 cylinder head 10 Lifter guide hole 18 End wall 19 Side wall 20 Raised part 21 Semi-cylindrical inner seat 25 Rotation blocking member 26 groove 27 holes 30 convex 31 Mounting part 41 Pressing part 50 Rotation blocking member 51 Mounting part

Continued front page    (72) Inventor Tomiho Hirano             10 Hamadashita, Nakahata-cho, Nishio-shi, Aichi Stock Association             Company Otics (72) Inventor Katsuhiko Motosugi             10 Hamadashita, Nakahata-cho, Nishio-shi, Aichi Stock Association             Company Otics (72) Inventor Shinichiro Kikuoka             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. (72) Inventor Hiroyuki Kawase             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. (72) Inventor Yoshito Moriya             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. (72) Inventor Hideo Naganaga             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. (72) Inventor Shuji Nakano             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. F-term (reference) 3G016 AA06 BA19 BB04 CA04 CA06                       CA20 CA25 CA29 CA57 DA09                       GA01                 3G018 AB07 AB16 BA04 BA10 DA17                       DA83 DA84 DA85 GA14

Claims (3)

[Claims] 1. A three-dimensional cam whose cam profile is continuously changed in the axial direction, and a displacement device which displaces the three-dimensional cam in the axial direction according to operating conditions such as the rotational speed of an internal combustion engine.
A variable valve mechanism including a direct-acting valve lifter that opens and closes a valve by reciprocating based on a cam profile of a solid cam, wherein the direct-acting valve lifter includes a cam contactor that contacts the solid cam and a cylinder head. And a cylindrical cup member slidably inserted into the lifter guide hole, the cup member is integrally molded from an end wall portion facing the solid cam and a side wall portion slidingly contacting the lifter guide hole. A mounting member formed by penetrating a side wall portion with a hole, a protrusion protruding to the outside of the side wall portion through the hole, and a mounting member formed so as not to pass through the hole and attached to the inner surface of the cup member. A variable valve operating mechanism is characterized in that a rotation preventing member integrally formed with a cylinder portion is attached, and a concave groove into which the convex portion is slidably fitted is formed in a lifter guide hole of a cylinder head. . 2. The variable valve mechanism according to claim 1, wherein the mounting portion is configured to be held in position by the cup member by pressing the inner surface of the side wall portion. 3. The variable valve mechanism according to claim 1, wherein the mounting portion is configured to be mounted by being fixed to the inner surface of the end wall portion by welding.