JP2007211615A - Valve system for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a valve system for an internal combustion engine which varies an operating angle of a valve system cam according to an amount of valve lift changed by a variable valve lift mechanism and eliminates the necessity of maintenance due to temporal change of a tappet clearance. <P>SOLUTION: The valve system for the internal combustion engine including the variable valve lift mechanism, is provided with a rocker arm 1 abutting on a cam 3 so as to press a valve 2 during rotation of the cam 3, and a hydraulic lash adjuster 4 arranged between the valve 2 and the rocker arm 1. A predetermined clearance is provided between a base circular portion 3A of the cam 3 and a roller 5 of the rocker arm 1. The clearance is secured by a stopper for controlling movement of the roller 5 to the cam 3. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a valve operating apparatus for an internal combustion engine, and more particularly to a valve operating apparatus for an internal combustion engine including a variable valve lift mechanism.

  In Japanese Patent Application Laid-Open No. 2004-36560 (Patent Document 1), an axis parallel to the rotational axis of the valve cam is provided on a rocker arm having a valve contact portion that contacts the engine valve and a cam contact portion that contacts the valve cam. The other end of the pair of link arms, one end of which is supported by the engine body so as to be able to swing around, is directly connected so as to be capable of relative rotation about an axis parallel to the rotation axis, and at least one of the link arms There is disclosed a valve operating apparatus for an internal combustion engine in which one end portion of the internal combustion engine is supported in a swingable manner on the engine body so as to be capable of stepless movement in a plane perpendicular to the rotational axis of the valve operating cam.

Japanese Patent Laying-Open No. 2005-16513 (Patent Document 2) is a valve operating apparatus for an engine including a variable valve lift mechanism that increases or decreases the valve lift amount without changing the valve opening angle. There is disclosed a valve operating apparatus for an engine that can reduce the tappet clearance in accordance with a decrease in the lift amount of the valve.
JP 2004-36560 A JP 2005-16513 A

  In a valve operating system including a variable valve lift mechanism, it is required to increase the operating angle of the valve operating cam when the valve lift is large, and to decrease the operating angle of the valve operating cam when the valve lift is small. .

  On the other hand, in Patent Document 1, a tappet clearance is formed by providing a tappet screw between the rocker arm and the engine valve. Changes may occur. Also, Patent Document 2 does not fully disclose a configuration that can solve the above-described problems.

  The present invention has been made in view of the above problems, and an object of the present invention is to change the operating angle of the valve cam according to the valve lift changed by the variable valve lift mechanism, and to tappet clearance. An object of the present invention is to provide a valve operating device for an internal combustion engine that can be maintenance-free with respect to secular change.

  A valve operating apparatus for an internal combustion engine according to the present invention is a valve operating apparatus for an internal combustion engine including a variable valve lift mechanism, which is in contact with a valve operating cam and presses the engine valve as the valve operating cam rotates. And a hydraulic lash adjuster provided between the engine valve and the rocker arm, and a predetermined clearance is provided between the base circle portion of the valve cam and the cam contact portion of the rocker arm.

  In the above configuration, a predetermined clearance is provided between the base circle portion of the valve cam and the cam contact portion of the rocker arm, so that the operating angle of the valve cam can be changed according to the valve lift. Become. In addition, since a hydraulic lash adjuster is provided between the engine valve and the rocker arm, it is possible to achieve maintenance-free with respect to secular changes in tappet clearance.

  Preferably, the valve operating device for the internal combustion engine further includes a link arm having one end connected to the internal combustion engine body and the other end connected to the rocker arm, the link arm having an axis parallel to the rotation axis of the valve operating cam. It is connected to the internal combustion engine main body and the rocker arm so as to be rotatable.

  According to the said structure, the lift amount of a valve cam can be changed because a link arm rotates.

  In the valve operating apparatus for an internal combustion engine, the clearance is preferably secured by means for restricting the movement of the cam contact portion of the rocker arm to the valve operating cam.

  According to the above configuration, a predetermined clearance can be provided between the base circle portion of the valve cam and the cam contact portion of the rocker arm with a simple structure.

  According to the present invention, in a valve operating apparatus for an internal combustion engine including a variable valve lift mechanism, the operating angle can be changed according to the valve lift, and maintenance-free with respect to secular change in tappet clearance can be achieved.

  Embodiments of a valve operating apparatus for an internal combustion engine according to the present invention will be described below. Note that the same or corresponding parts are denoted by the same reference numerals, and the description thereof may not be repeated.

  FIG. 1 is a view showing a valve operating apparatus for an internal combustion engine according to an embodiment of the present invention. Referring to FIG. 1, the valve operating apparatus for an internal combustion engine according to the present embodiment includes a rocker arm 1, a valve 2, a cam 3, and a hydraulic lash adjuster 4. A roller 5 is attached to the rocker arm 1. The internal combustion engine may be a gasoline engine or a diesel engine. The internal combustion engine is mounted on a vehicle.

  The rocker arm 1 is connected to a valve 2 via a hydraulic lash adjuster 4. The rocker arm 1 is connected to the link arm 6 via a connecting shaft 8. The rocker arm 1 is connected to the link arm 9 via a roller 5 and a connecting shaft 11.

  The cam 3 has a base circle portion 3A and a nose portion 3B. The link arms 6 and 9 rotate around the support shafts 7 and 10, respectively. Each of the link arms 6 and 9 is rotatable with respect to the rocker arm 1. When the link arm 6 rotates in the direction of the arrow DR1, the lift amount of the valve 2 is changed. That is, the valve operating apparatus for an internal combustion engine according to the present embodiment includes a variable valve lift mechanism.

  A predetermined clearance is provided between the base circle portion 3A of the cam 3 and the roller 5 attached to the rocker arm 1 as shown in FIG. When the cam 3 rotates from the state shown in FIG. 1, the nose portion 3B of the cam 3 and the roller 5 come into contact with each other. The roller 5 is pressed downward in FIG. As a result, the rocker arm 1 pushes down the valve 2 and the valve open state is realized. Thereafter, when the cam 3 further rotates, the cam 3 and the roller 5 are separated from each other, and the valve 2 returns to the original state (that is, the valve closed state).

  FIG. 2 is a diagram for explaining the relationship between the valve lift amount and the valve opening / closing timing. With reference to FIG. 2, the case where the valve lift is large and the case where the valve lift is small are realized by the rotation of the link arm 6 described above. Here, if a clearance is not formed between the base circle 3A of the cam 3 and the roller 5, the operating angle cannot be changed depending on whether the valve lift is large or small. On the other hand, when a component (for example, a screw) for forming a tappet clearance is provided between the rocker arm 1 and the valve 2, a lash adjuster cannot be provided between the rocker arm 1 and the valve 2, and the tappet clearance is not provided. It becomes difficult to make maintenance-free against changes over time.

  On the other hand, in the valve operating apparatus for the internal combustion engine according to the present embodiment, the clearance is provided between the cam 3 and the roller 5 so that the operating angle (α) when the valve lift is large is small. In this case, the operating angle (β) can be made larger. Further, since it is not necessary to provide a part for forming a tappet clearance between the rocker arm 1 and the valve 2, the hydraulic lash adjuster 4 can be provided between the rocker arm 1 and the valve 2. By providing the hydraulic lash adjuster 4, the clearance between the cam 3 and the roller 5 can be kept constant. As a result, maintenance-free with respect to secular change of tappet clearance can be achieved.

  Next, a mechanism for restricting the movement of the roller 5, which is the “cam contact portion” of the rocker arm 1, to the cam 3 will be described with reference to FIG. 3. As shown in FIG. 3, for example, by providing a stopper 12 made of a screw, the rotation of the link arm 9 in the direction of the arrow DR2 is suppressed. Thereby, the movement of the roller 5 toward the cam 3 is suppressed, and a predetermined clearance (L) is formed between the base circle 3 </ b> A of the cam 3 and the roller 5. Thus, in the valve operating apparatus for an internal combustion engine according to the present embodiment, a clearance can be formed between the base circle portion 3A of the cam 3 and the roller 5 with a simple structure.

  FIG. 4 is a side sectional view of the hydraulic lash adjuster 4. Referring to FIG. 4, the hydraulic lash adjuster 4 has a body 41. In the body 41, a plunger spring 42, a ball retainer 43, a check ball spring 44, a check ball 45, and a plunger 46 are disposed. A high pressure chamber 47 is formed between the bottom of the body 41 and the bottom of the plunger 46, and a low pressure chamber 48 is formed inside the plunger 46. The high pressure chamber 47 is filled with oil for lubricating the internal combustion engine. The high-pressure chamber 47 and the low-pressure chamber 48 communicate with each other via a communication passage 49 formed in a partition portion 49A located at the lower portion of the plunger 46, and the body 41 and the plunger 46 are formed in the low-pressure chamber 48. Oil is supplied through an oil hole (not shown). The oil supplied to the low pressure chamber 48 is discharged from an oil pump that is driven as the internal combustion engine is operated, and reaches the oil hole through an oil passage described later.

  A plunger spring 42 and a ball retainer 43 are disposed in the high pressure chamber 47. The urging force of the plunger spring 42 acts on the plunger 46 via the ball retainer 43, so that the plunger 46 is always urged in a direction protruding from the body 41. In the high pressure chamber 47, a check ball spring 44 and a check ball 45 are disposed between the ball retainer 43 and the bottom of the plunger 46. The urging force of the check ball spring 44 acts on the check ball 45 so that the check ball 45 is held at a position where the communication path 49 is blocked.

  Therefore, if the valve 2 and the hydraulic lash adjuster 4 are about to separate after the intake valve 2 starts to close during operation of the internal combustion engine, the plunger spring 42 extends and the plunger 46 advances from the body 41 (that is, hydraulic type). Rush adjuster 4 extends).

  When the hydraulic lash adjuster 4 is extended as described above, the pressure in the high pressure chamber 47 decreases as the volume of the high pressure chamber 47 increases, and the force based on the differential pressure between the high pressure chamber 47 and the low pressure chamber 48 is checked. It acts on the ball 45. Then, when the check ball 45 is displaced to a position where the blocking of the communication passage 49 is released against the urging force of the check ball spring 44 by the force based on the differential pressure, oil flows from the low pressure chamber 48 to the high pressure chamber 47. Become. Thereafter, when the magnitude of the force based on the differential pressure becomes equal to or less than the urging force of the check ball spring 44, the check ball 45 is returned to a position where the communication path 49 is blocked.

  On the other hand, when the rocker arm 1 is pushed by the cam 3 when the valve 2 is opened, the force is transmitted to the body 41 and the plunger 46 tries to enter the body 41. At this time, since the communication passage 49 is blocked by the check ball 45, oil outflow from the high pressure chamber 47 to the low pressure chamber 48 is suppressed. The oil filled in the high pressure chamber 47 suppresses the movement of the plunger 46 in the direction of reducing the volume of the high pressure chamber 47, in other words, the plunger 46 entering the body 41.

  When the plunger 46 tries to enter the body 41 in this way, a small amount of oil in the high pressure chamber 47 passes between the inner peripheral surface of the body 41 and the outer peripheral surface of the plunger 46, and the hydraulic lash adjuster 4 As a result, the plunger 46 slightly sinks into the body 41. However, the approach of the plunger 46 into the body 41 is recovered by the operation of the hydraulic lash adjuster 4 after the valve 2 starts to close.

  FIG. 5 is a view for explaining an oil passage for supplying oil to the hydraulic lash adjuster 4. Referring to FIG. 5, oil is supplied to hydraulic lash adjuster 4 through oil passage 13. The oil passage 13 reaches the hydraulic lash adjuster 4 from the support shaft 7 through the link arm 6, the connecting shaft 8, and the rocker arm 1. Oil is supplied to the hydraulic lash adjuster 4 through the oil passage 13. An oil passage may be formed in the cylinder head of the internal combustion engine, and the oil may be supplied to the hydraulic lash adjuster 4 through the oil passage.

  The above contents are summarized as follows. In other words, the valve operating apparatus for an internal combustion engine according to the present embodiment is a valve operating apparatus including a variable valve lift mechanism, which is in contact with the cam 3 as a “valve cam” and rotates with the cam 3. A rocker arm 1 that pushes the valve 2 as an “engine valve” and a hydraulic lash adjuster 4 provided between the valve 2 and the rocker arm 1, a base circle portion 3 A of the cam 3 and a “cam contact portion of the rocker arm 1. A predetermined clearance L is provided between the roller 5 and The clearance is secured by a stopper 12 as a means for restricting the movement of the roller 5 to the cam 3.

  The valve operating apparatus for the internal combustion engine further includes a link arm 6 having one end connected to the internal combustion engine body and the other end connected to the rocker arm 1. The link arm 6 is connected to the internal combustion engine body and the rocker arm 1 so as to be rotatable about an axis parallel to the rotation axis of the cam 3.

  In the valve gear according to the present embodiment, a predetermined clearance (L) is provided between the base circle portion 3A of the cam 3 and the roller 5 provided on the rocker arm 1, so that the cam 3 according to the valve lift. It becomes possible to change the working angle of the. Further, by providing the hydraulic lash adjuster 4 between the rocker arm 1 and the valve 2, it is possible to achieve maintenance-free with respect to secular change of the tappet clearance.

  Although the embodiments of the present invention have been described above, the embodiments disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is the figure which showed the valve operating apparatus of the internal combustion engine which concerns on one embodiment of this invention. It is a figure explaining the relationship between valve lift amount and valve opening and closing timing. It is a figure explaining the mechanism which controls the movement to the valve cam of the cam contact part of a rocker arm. It is sectional drawing which shows the hydraulic lash adjuster in the valve operating apparatus of the internal combustion engine which concerns on one embodiment of this invention. It is a figure explaining the oil path which supplies oil to the hydraulic lash adjuster in the valve operating apparatus of the internal combustion engine which concerns on one embodiment of this invention.

Explanation of symbols

  1 Rocker arm, 2 valve, 3 cam, 3A base circle, 3B nose, 4 hydraulic lash adjuster, 5 roller, 6 link arm, 7 support shaft, 8 connection shaft, 9 link arm, 10 support shaft, 11 connection shaft , 12 Stopper, 13 Oil passage, 41 Body, 42 Plunger spring, 43 Ball retainer, 44 Check ball spring, 45 Check ball, 46 Plunger, 47 High pressure chamber, 48 Low pressure chamber, 49 Communication path, 49A Partition.

Claims (3)

A valve operating apparatus for an internal combustion engine including a variable valve lift mechanism,
A rocker arm that contacts the valve cam and pushes the engine valve as the valve cam rotates;
A hydraulic lash adjuster provided between the engine valve and the rocker arm;
A valve operating apparatus for an internal combustion engine, wherein a predetermined clearance is provided between a base circle portion of the valve operating cam and a cam contact portion of the rocker arm. A link arm having one end connected to the internal combustion engine body and the other end connected to the rocker arm;
2. The valve operating device for an internal combustion engine according to claim 1, wherein the link arm is connected to the internal combustion engine main body and the rocker arm so as to be rotatable about an axis parallel to a rotation axis of the valve operating cam.   3. The valve operating apparatus for an internal combustion engine according to claim 1, wherein the clearance is secured by means for restricting movement of the cam contact portion of the rocker arm to the valve operating cam. 4.

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