JP2005220838A - Variable valve system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable valve system for further reducing sliding resistance between a cam provided on a cam shaft and a rocking cam for opening/closing an on-off valve. <P>SOLUTION: The variable valve system adjusts the lift amount and the opening/closing timing of the on-off valve 5 provided in an engine. It comprises a rocking lever 29 which rocks with the cam 21 provided on the rotatable cam shaft 19, a rocking cam supporting member 23 for rockingly supporting the rocking cam 27 which rocks with the rocking of the rocking lever 29, and the on-off valve 5 to be opened/closed with the rocking of the rocking cam 27. The rocking lever 29 and the rocking cam 27 have slide contact with each other at their slide contact faces, and the rocking lever 29 and the rocking cam 27 have the same turning direction at their slide contact faces. The rocking cam supporting member 23 is position adjustable in the direction approximately perpendicular to the moving direction of the on-off valve 5. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a variable valve gear that can adjust the opening / closing timing and valve lift amount of an intake valve and an exhaust valve provided in an engine, and more specifically, a swing cam and a cam that open and close the intake valve and the exhaust valve The present invention relates to a variable valve gear that can further reduce sliding resistance with a cam provided on a shaft.

Conventionally, as a configuration for opening and closing an intake valve and an exhaust valve provided in an engine, there is a configuration in which a valve lifter (valve tappet) provided in the intake valve and the exhaust valve is directly pressed by a cam provided in a rotatable cam shaft. is there. In addition, a swing cam or a rocker arm is arranged between the cam and the valve lifter of each valve, so that the opening / closing timing and lift amount of the intake valve and exhaust valve can be adjusted. There is also a configuration for adjusting the rotational center position of the moving cam or the rocker arm (see, for example, Patent Document 1).
Japanese Patent Application Laid-Open No. 64-53009

  In the configuration described in Patent Document 1, the rotation direction of the cam shaft provided with the cam and the rotation direction around the axis of the rocker arm rotated by being pressed by the cam are, for example, clockwise or counterclockwise. It is the same direction as the direction. Accordingly, when the rotation direction at the contact position between the cam and the rocker arm is viewed, the rotation is performed in opposite directions.

  Therefore, in the above configuration, when the frictional resistance at the contact surface between the cam and the rocker arm increases, the force with which the cam presses the rocker arm toward the rotation center side of the rocker arm increases and the contact by the component force occurs. Pressure tends to increase and wear tends to be accelerated. Further, when the frictional resistance increases, the camshaft torque may be adversely affected.

  The present invention has been made in view of the conventional problems as described above, and is a variable valve apparatus for adjusting the lift amount and opening / closing timing of an on-off valve provided in an engine, and is provided on a rotatable cam shaft. A swing lever that is swung by the swung cam, a swing cam that is swung by swinging of the swing lever, and the on-off valve that is opened and closed by swinging of the swing cam, The rocking lever and the rocking cam are slidably contacted with each other on a sliding surface, and both rotation directions are the same in a sliding contact portion between the rocking lever and the rocking cam. To do.

  The present invention also provides a variable valve operating device for adjusting the lift amount and opening / closing timing of an on-off valve provided in an engine, and a swing cam swinged by a cam provided on a rotatable cam shaft, And the on-off valve that is opened and closed by the swing of the swing cam, the cam and the swing cam are in sliding contact with each other on the sliding contact surface, and the sliding contact between the cam and the swing cam In the part, both rotation directions are the same direction.

  Further, the present invention is characterized in that, in the variable valve operating apparatus, the position of the swing cam support member is adjustable in a direction substantially perpendicular to the moving direction of the on-off valve.

  According to the present invention, the sliding contact portion between the swing cam for opening and closing the intake valve and the exhaust valve and the cam provided on the cam shaft, or the slide between the swing lever and the swing cam swinged by the cam. In the contact portion, both the sliding directions in sliding contact with each other are the same direction, so the sliding contact portion of the cam or the swing lever with the swing cam slides toward the free end side of the swing cam. It is.

  Therefore, even when the frictional resistance at the sliding contact portion between the cam or the swing lever and the swing cam is increased, the cam or the swing lever moves the swing cam to the rotation center of the swing cam. There is no effect of pressing to the side, and the conventional problems as described above can be solved.

  Hereinafter, embodiments of the present invention using the drawings will be described. Since the configuration of the engine, the cam shaft support structure, the configuration for rotating the cam shaft, and the like are already known, the main parts according to the present invention are described below. The configuration is schematically and conceptually illustrated and described.

  As is well known, the cylinder head of the engine is provided with an intake hole and an exhaust hole. The intake hole is provided with an intake valve for opening and closing the intake hole, and the exhaust hole is provided with an exhaust valve for opening and closing the exhaust hole.

  In the present specification, hereinafter, the intake holes and exhaust holes are collectively referred to as “intake / exhaust holes”, and the intake valves and exhaust valves are collectively referred to as “valves” or “open / close valves”. To do.

  Now, referring to FIG. 1, a cylinder head 1 of an engine (not shown) is provided with an intake / exhaust hole 3, and a valve (open / close valve) 5 for opening / closing the intake / exhaust hole 3 is provided in the intake / exhaust hole 3. Is provided. The stem 7 in the on-off valve (valve) 5 is guided and supported by a stem guide 9 provided in the cylinder head 1 so as to be movable up and down, and a cup-shaped valve lifter 11 is provided at the upper end of the stem 7.

  The on-off valve 5 always closes the intake / exhaust hole 3 upward by a valve spring 17 elastically mounted between a spring seat 13 provided in the stem guide 9 and a spring seat 15 provided in the valve lifter 11. It is biased in the direction.

  In addition, since the structure which supports the said on-off valve 5 or the cylinder head 1 so that the said on-off valve 5 can be moved up and down may be a well-known structure, the detailed description about the on-off valve 5 and its support structure is abbreviate | omitted.

  Further, the cylinder head 1 is provided with a cam shaft 19 rotatably, and the cam shaft 19 is provided with a plurality of cams 21 corresponding to the number of the on-off valves 5. In addition, since the drive system for rotating the cam shaft 19 is well known, the detailed configuration and operation of the drive system for rotating the cam shaft 19 are omitted.

  In order to adjust the valve timing by making the opening / closing timing (opening / closing operation timing) of the on-off valve 5 and the lift amount of the on-off valve 5 variable, a valve timing adjustment mechanism is provided between the cam shaft 19 and the on-off valve 5. Is provided. In other words, the cylinder head 1 is provided with a swing cam support member 23 whose position is adjustable in a direction substantially perpendicular to the opening / closing operation direction (movement direction) of the on-off valve 5. A swing cam 27 is supported on the member 23 via a support shaft 25 so as to be swingable (turnable).

  The swing cam support member 23 is moved by an operating mechanism (not shown) operated by an appropriate actuator (not shown) such as a servo motor appropriately provided in a part of the cylinder head 1 or an accelerator pedal. Position adjustment is performed.

  The swing cam 27 moves up and down the on-off valve 5 by swinging (turning) about the support shaft 25. The swing cam 27 is always on the upper surface of the valve lifter 11. A cam-like valve pressing surface 27 </ b> A that is capable of contacting and pressing the valve lifter 11 is provided. The rocking cam 27 is provided with a cam-like pressed surface 27B that is pressed by the rocking lever 29 interposed between the cam 21 or the cam 21 and the rocking cam 27. The moving cam 27 is formed in a bell crank shape as a whole.

  In the state shown in FIG. 1, even if the swing cam support member 23 is moved to change the position of the support shaft 25, the shaft center of the support shaft 25 to the upper surface of the valve lifter 11 is changed. The dimensions are kept constant.

  The swing lever 29 has a bell crank-like structure supported by a part of the cylinder head 1 via a support shaft 31 so as to be swingable (turnable). The cam follower 33 contacting the cam 21 is rotatably provided. A cam-like pressing surface 29A formed at the tip of the swing lever 29 is in contact with the pressed surface 27B of the swing cam 27 so as to be relatively slidable.

  The contact (contact) relationship between the pressing surface 29A of the swing lever 29 and the pressed surface 27B of the swing cam 27 is the pressed surface of the swing cam 27 with the pressing surface 29A of the swing lever 29. When the swing cam 27 is rotated by pressing 27B, the valve pressing surface 27A provided on the swing cam 27 has a relationship of lowering (opening) the on-off valve 5 against the urging force of the valve spring 17. .

  Then, the rotation direction (swing direction) of the swing cam 27 around the support shaft 25 and the rotation direction (swing direction) of the swing lever 29 around the support shaft 31 are opposite to each other. It is. In other words, when one is rotating in the clockwise direction, the other rotating direction is the counterclockwise direction. When the rotating directions at both contact portions (sliding contact portions) are seen, The direction of movement is the same direction. In other words, when both rotation directions in the sliding contact portion are indicated by arrows, for example, both the directions of the arrows are upward and are in the same direction.

  In the above configuration, when the cam shaft 19 rotates and the swing lever 29 is rotated (swing) by the cam 21 provided on the cam shaft 19, the swing of the swing lever 29 is applied to the swing cam 27. As a result, the on-off valve 5 is opened and closed. Here, when the swing cam support member 23 is moved to adjust the position of the support shaft 25, the contact position (contact position) between the pressing surface 29 </ b> A of the swing lever 29 and the pressed surface 27 </ b> B of the swing cam 27. Changes, and the lever ratio of the swing cam 27 changes. Therefore, the lift amount and opening / closing timing of the opening / closing valve 5 are adjusted.

  In the above configuration, when the rocking cam 27 is rotated by pressing the pressed surface 27B of the rocking cam 27 by the pressing surface 29A of the rocking lever 29, the pressing surface 29A and the rocking cam 27 of the rocking lever 29 are rotated. The position of the contact with the pressed surface 27B gradually moves toward the tip (free end) side of the swing cam 27.

  Therefore, even when the frictional resistance between the pressing surface 29A of the swing lever 29 and the pressed surface 27B of the swing cam 27 is large, a component force that presses the swing cam 27 toward the support shaft 25 is provided. There is nothing that can happen. In other words, when the frictional resistance is increased, the pressed surface 27B of the swing cam 27 is likely to be separated from the pressing surface 29A of the swing lever 29 by the action of a component force, and the frictional resistance is increased. Is suppressed.

  Therefore, the adverse effects on wear and camshaft torque due to the increase in the frictional resistance are suppressed, and the conventional problems as described above can be solved.

  FIG. 2 conceptually and schematically shows a second embodiment according to the present invention. Components having the same functions as those of the above-described embodiment are denoted by the same reference numerals, and redundant description is omitted. And

  In the second embodiment, the camshaft 19 and the cam 21 are separately provided corresponding to the intake valve and the exhaust valve, respectively, and the rocking lever 29 is omitted, and the rocking by contact of the cam 21 is performed. The moving cam 27 is directly rocked. The swing cam 27 is symmetrically disposed outside the cam 21.

  Further, in the above configuration, the cam shaft 19 rotates in the opposite direction, and the contact position P between the cam 21 and the swing cam 27 is determined by the rotation center of the cam 21 and the swing cam. The cam 21 is positioned below the rotation direction as seen in the rotation direction when the cam 21 presses the swing cam 27 and rotates.

  Therefore, according to the said structure, while being able to show | play the effect similar to embodiment mentioned above, the simplification of a structure can be aimed at by omitting the rocking lever.

  FIG. 3 conceptually and schematically shows the third embodiment, and corresponds to a modification of the second embodiment. That is, in this embodiment, each cam shaft 19 is configured to rotate in the same direction, and each swing cam 27 is disposed on one side of each cam 21 (on the right side in FIG. 3). is there. In the third embodiment, the same effects as described above can be obtained.

  FIG. 4 conceptually and schematically shows the fourth embodiment. One swing cam 27 for opening and closing one open / close valve 5 is configured to be in direct contact with the cam 21. A swing lever 35 similar to the swing lever 29 is swingably provided between the swing cam 27 and the cam 21 for opening and closing the other opening / closing valve 5. Even in this configuration, the same effects as in the above-described embodiment can be obtained.

It is explanatory drawing which shows the structure which concerns on 1st Embodiment of this invention. It is explanatory drawing which shows notionally and schematically the structure which concerns on the 2nd Embodiment of this invention. It is explanatory drawing which shows notionally and schematically the structure which concerns on the 3rd Embodiment of this invention. It is explanatory drawing which shows notionally and schematically the structure which concerns on the 4th Embodiment of this invention.

Explanation of symbols

1 Cylinder head 3 Air intake / exhaust hole 5 Open / close valve
11 Valve Lifter 19 Cam Shaft 21 Cam 23 Swing Cam Support Member 25 Support Shaft 27 Swing Cam 29 Swing Lever 31 Support Shaft

Claims (3)

  A variable valve device for adjusting the lift amount and opening / closing timing of an on-off valve provided in an engine, wherein the swing lever is swung by a cam provided on a rotatable cam shaft, A swing cam that swings by swinging, and the on-off valve that opens and closes by swinging the swing cam. The swing lever and the swing cam are in sliding contact with each other on a sliding contact surface. And a variable valve operating device characterized in that both the rotating directions are the same in the sliding contact portion between the swing lever and the swing cam.   A variable valve operating device for adjusting a lift amount and opening / closing timing of an on-off valve provided in an engine, wherein the swing cam is swung by a cam provided on a rotatable cam shaft, The opening / closing valve that is opened and closed by swinging, the cam and the swinging cam are in sliding contact with each other on the sliding contact surface, and the sliding contact portion between the cam and the swinging cam is in both rotations. A variable valve operating device characterized in that the moving direction is the same direction. 3. The variable valve operating apparatus according to claim 1, wherein the position of the swing cam support member is adjustable in a direction substantially perpendicular to a moving direction of the on-off valve. .

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